A linear compressor driving apparatus having an inverter which supplies a driving current of a predetermined frequency to a linear compressor. The linear compressor driving apparatus further includes an inverter controller for controlling the inverter on the basis of resonance frequency information so that the frequency of an output current from the inverter becomes equal to the resonance frequency, and instantaneous values of an output current and an output voltage from the inverter are measured at a phase timing in which an amount of change in the output current of the inverter becomes zero. A piston stroke is calculated from these measured values. In such a linear compressor driving apparatus, a stroke and a top clearance of the piston of the linear compressor can be accurately detected by relatively simple arithmetic processing without using a position sensor.

The present invention relates to a linear compressor driving apparatus and, more particularly, to an apparatus for driving a linear compressor which generates a compressed gas in a cylinder by making a piston reciprocate with a linear motor.
A linear compressor utilizing a mechanical elastic member or elasticity of a gas has conventionally been known as an apparatus for generating a compressed gas.
FIG. 7 is a cross-sectional view for explaining a conventional linear compressor, and illustrates a concrete configuration of a linear compressor using a spring as an elastic member.
A linear compressor 100 has a cabinet 71 comprising a cylinder section 71a and a motor section 71b which are adjacent to each other. The cylinder section 71a of the cabinet 71 forms a cylindrical-shaped cylinder of the linear compressor 100. In the cylinder section 71a, a piston 72 is provided slidably along a direction parallel to a center axis of the cylinder (the piston axis direction).
On the back of the piston 72 in the cabinet 71, a piston rod 72a is placed in the cylinder section 71a and the motor section 71b, and an end of the piston rod 72a is fixed to the piston 72. Further, a support spring (resonance spring) 81 is placed between the other end of the piston rod 72a and an inner wall 71b1 of the motor section 71b which is opposed to the piston rod 72a. The support spring 81 deforms when the piston 72 is displaced from a piston neutral position (piston reference position), and, when the support spring 81 is deformed, the support spring 81 applies a force to the piston 72 so that the piston 72 returns to the piston reference position. Further, the piston neutral position is a piston position where the support spring 81 is not deformed, and no force is applied from the support spring 81 to the piston 72 when the piston 72 is located in the piston neutral position.
Further, a magnet 73 is fixed to a portion of the piston rod 72a, which portion is located in the motor section 71b, and an electromagnet 74 comprising an outer yoke 74a and a stator coil 74b, embedded in the outer yoke 74a is fixed to a portion of the inner wall of the motor section 71b, which portion is opposed to the magnet 73.
A linear motor 82 is constituted by the electromagnet 74 and the magnet 73. That is, in the linear compressor 100, the piston 72 reciprocates along its axis direction by the driving force of the linear motor 82, i.e., the electromagnetic force generated between the electromagnet 74 and the magnet 73, and the elasticity of the support spring 81.
On the other hand, a compression chamber 76, which is a closed space surrounded by a cylinder upper portion inner wall 75, a piston compression wall 72b, and a cylinder peripheral wall 77, is formed at the cylinder head side of the cabinet 71. An end of a cooling medium inlet tube 1a for drawing a low-pressure cooling medium gas into the compression chamber 76 is opened at the cylinder upper portion inner wall 75 and, further, an end of a tooling medium discharge tube 1b for discharging a high-pressure cooling medium gas from the compression chamber 76 is opened at the cylinder upper portion inner wall 75. An inlet valve 79 and a discharge valve 80 for preventing a back flow of the cooling medium gas are fixed to the cooling medium inlet tube la and the cooling medium discharge tube 1b, respectively.
In the linear compressor 100 having the above-described structure, the piston 72 reciprocates in its axis direction by an intermittent supply of a driving current from a motor driver (not shown) to the linear motor 82, whereby drawing of the low-pressure cooling medium gas into the compression chamber 76, compression of the cooling medium gas in the compression chamber 76, and discharge of the compressed high-pressure cooling medium gas from the compression chamber 76 are repeatedly carried out.
By the way, in the above-mentioned linear compressor 100, even when a current or voltage applied to the linear motor 82 is kept at a constant value, if the state of the load applied onto the linear compressor changes, the stroke of the piston 72 changes. Therefore, especially in a refrigeration compressor using the linear compressor 100, since the thermodynamic efficiency of a refrigerating cycle is significantly improved by controlling the flow of the cooling medium according to the varying environmental temperature, a means for detecting the stroke of the piston 72 that determines the flow of cooling medium (piston stroke detection means) is needed.
Further, in the linear compressor 100, from its structural viewpoint, there is a danger in that the front end of the piston might collide with the upper wall of the cylinder.
To be specific, the piston 72 receives not only the piston driving force of the linear motor 82 and the elasticity of the support spring 81 but also a force caused by a differential pressure between the pressure of the cooling medium gas in the compression chamber 76 and the back pressure of the piston 72, whereby the center position of the reciprocating motion of the piston 72 (hereinafter also referred to as piston amplitude center position) is offset with respect to the piston amplitude center position when the differential pressure is zero, i.e., the piston position when the support spring is not deformed (piston neutral position). Therefore, when the internal pressure of the compression chamber 76 that acts on the piston 72 is increased/decreased due to a change of the load state, not only the stroke of the piston 72 but also the center position of the reciprocating motion of the piston 72 might change.
In order to prevent collision of the piston with the cylinder, not only the stroke detection means but also a position detection means for detecting the distance between the front end of the piston and the inner wall of the cylinder head are required. For example, in a linear compressor having no collision prevention means, the front end of the piston hits the inner wall of the cylinder head, resulting in uncomfortable noise or damage to the piston or the cylinder.
There is employed, as the above-mentioned position detection means, a sensor which can detect the degree of displacement of the piston (piston displacement) with respect to the piston reference position such as the piston neutral position, without contacting the movable members such as the piston in the linear compressor 100. For example, a displacement meter using an eddy current system, a displacement meter using a differential transformer, and the like are employed.
However, when such sensor is used, the production cost of the linear compressor 100 is increased and, moreover, a space for mounting the sensor is needed, which leads to an increase in the size of the cabinet 71 of the linear compressor 100. Further, since the sensor is used while being exposed to a high-temperature and high-pressure gas in the compressor 100, there occurs a problem with then reliability of the sensor itself, in other words, a problem in that a sensor which can be reliably used under a high-temperature and high-pressure atmosphere is desired.
So, as a method for detecting the position of the piston 72, there is proposed a method of directly measuring the linear motor driving current and voltage which are supplied to the linear compressor 100, and deriving the position of the piston 72 on the basis of the measured values without using a position sensor placed in the linear compressor 100 (refer to Japanese Unexamined Patent Publication No. Hei. 8-508558).
Hereinafter, a description will be given of a piston position detection method used for a linear compressor, which is described in the above-mentioned literature.
FIG. 8 is a diagram illustrating an equivalent circuit of a linear motor for driving a piston of a linear compressor.
In FIG. 8, L indicates an equivalent inductance [H] of a coil as a component of the linear motor, and R indicates an equivalent resistance [xcexa9] of the coil. Further, V indicates an instantaneous voltage [V] applied to the linear motor, and I indicates a current [A] applied to the linear compressor. Further, xcex1xc3x97v indicates an induced electromotive voltage [V] which is generated when the linear motor is driven, wherein xcex1 is a thrust constant [N/A] of the linear motor, and v is an instantaneous velocity [m/s] of the linear motor.
The thrust constant xcex1 of the linear motor indicates a force [N] which is generated when a unit current [A] is passed through the linear motor. Although the unit of the thrust constant xcex1 is expressed by [N/A], this unit is equivalent to [Wb/m] or [Vxc2x7s/m].
The equivalent circuit shown in FIG. 8 is derived from the Kirchhoff""s law, and an instantaneous velocity v [m/s] of the linear motor is obtained from the equivalent circuit.
That is, under the driving state of the linear motor, the voltage (V) applied to the linear motor is balanced with the sum of a dropped voltage (Ixc3x97R) [V] due to the equivalent resistance of the coil of the linear motor, a dropped voltage (Lxc2x7dI/dt) [V] due to the equivalent inductance of the coil, and the induced electromotive voltage (xcex1xc3x97v) [V] that is generated when driving the linear motor, and the following formula (1) holds.                     v        =                              1            α                                          (                          V              -                              R                xc3x97                I                            -                              L                                                                      ⅆ                    I                                                        ⅆ                    t                                                                        )                                              (        1        )
The coefficients xcex1[N/A], R[xcexa9], and L[H] used in formula (1) are constants unique to the motor, and these constants are already-known values. Accordingly, the instantaneous velocity v[m/s] can be obtained from these constants and the applied voltage V[V] and current I[A], which are measured, on the basis of formula (1).
Further, a piston displacement (a distance from an undefined reference position to the piston) xc3x97[m] is obtained by a time integration of the instantaneous velocity v[m/s] as represented by the following formula (2). In formula (2), the constant Const. is the piston displacement at the start of integration.
xe2x80x83x=∫vdt+Const.xe2x80x83xe2x80x83(2)
As described above, in the piston position detection method disclosed in the above-described literature, the measured values V and I of the applied voltage and current to the linear motor are subjected to arithmetic processing including differentiation based on formula (1) to obtain the instantaneous velocity v of the piston, and further, the instantaneous velocity v is subjected to arithmetic processing including integration based on formula (2), whereby the piston displacement x can be calculated.
However, the piston displacement x obtained by the arithmetic processing based on formulae (1) and (2) is a displacement with reference to a certain position on the piston axis, and a distance from the cylinder head to the piston top dead point position cannot be obtained directly from the displacement x.
To be specific, when the linear compressor 100 is under a loaded condition, the piston center position (piston amplitude center position) in the piston reciprocating motion is offset with respect to the piston neutral position (i.e., the piston amplitude center position when the pressure in the compression chamber is equal to the back pressure) by the pressure of the cooling medium gas, and the piston reciprocates around the offset piston amplitude center position. In other words, the piston displacement x obtained by formula (2) includes an average component.
However, every actual analog integrator or digital integrator does not perform ideal integration processing for outputting a perfect response signal with respect to a constant or a DC input, but it is restricted in responding to a DC input. Therefore, an actual integrator cannot subject the piston displacement x to integration processing in which its average component is reflected. The reason why the DC response of the actual integrator is restricted is because the output of the integrator should be prevented from being saturated by an unavoidable DC component in the input signal.
As a result, the piston displacement x[m] obtained by the integration processing based on formula (2) using an actual integrator is not a displacement from which an actual distance between the piston and the cylinder head can be directly obtained, but a displacement simply indicating the piston position with reference to a certain point on the piston axis.
Therefore, the piston displacement x[m] obtained from formula (2) is converted into a piston displacement xxe2x80x2 indicating the piston position with respect to the piston amplitude center position. Further, using the converted piston displacement xxe2x80x2, arithmetic processing for obtaining a piston displacement xxe2x80x3 with reference to the cylinder head and indicating the piston amplitude center position is carried out.
Hereinafter, these arithmetic processings will be described in detail.
FIG. 9 is a diagram schematically illustrating the piston position in the cylinder.
Initially, the three coordinate systems shown in FIG. 9, i.e., a first coordinate system X, a second coordinate system Xxe2x80x2, and a third coordinate system Xxe2x80x3, will be briefly described.
The first coordinate system X is a coordinate system expressing the piston displacement x, and the first coordinate system X has, as an origin (x=0), a certain point Paru on the piston axis. Accordingly, the absolute value of the displacement x indicates the distance from the point Paru to the piston front end position P.
The second coordinate system Xxe2x80x2 is a coordinate system expressing the piston displacement xxe2x80x2, and the second coordinate system Xxe2x80x2 has, as an origin (xxe2x80x2=0), the piston amplitude center position Pav. Accordingly, the absolute value of the displacement xxe2x80x2 indicates the distance from the amplitude center position Pav to the piston front end position P.
The third coordinate system Xxe2x80x3 is a coordinate system expressing the piston displacement xxe2x80x3, and the third coordinate system Xxe2x80x3 has, as an origin (xxe2x80x3=0), the cylinder head position Psh on the piston axis. Accordingly, the absolute value of the displacement xxe2x80x3 indicates the distance from the cylinder head position Psh to the piston front end position P.
Next, an arithmetic operation for obtaining the piston displacement xxe2x80x3 will be described.
A piston position (piston top dead point position) Ptd in which the piston is closest to the cylinder head 75 is indicated by a displacement xtd on the first coordinate system X, and a piston position (piston bottom dead point position) Pbd in which the piston is farthest from the cylinder head 75 is indicated by a displacement xbd on the first coordinate system X. Then, a piston stroke Lps[m] is obtained from a difference between the displacement xtd corresponding to the piston top dead point position Ptd on the first coordinate system X and the displacement xbd corresponding to the piston bottom dead point position Pbd on the first coordinate system X.
Further, the piston amplitude center position Pav in the state where the piston is reciprocating is a position which is apart from the displacement xtd of the piston position (piston top dead point position) Ptd in which the piston is closest to the cylinder head by a length (Lps/2) that is equal to half the piston stroke Lps[m] from the cylinder head. Accordingly, the piston amplitude center position Pav is expressed by a displacement xav (=(xbdxe2x88x92xtd)/2) on the first coordinate system X.
Further, when the constant Const. in formula (2) is zero, a new function that indicates the piston position P by the piston displacement xxe2x80x2[m] is derived with the piston amplitude center position Pav as a reference (origin), in other words, on the second coordinate system Xxe2x80x2.
Next, a description will be given of a method for obtaining the piston displacement xxe2x80x3 indicating the piston amplitude center position on the third coordinate system Xxe2x80x3 with the cylinder head position Psh as an origin.
Under the state where the linear compressor 100 draws in the cooling medium gas (inlet state), i.e., under the state where the inlet valve is open, both the pressure in the compression chamber and the pressure on the back of the piston are equal to the cooling medium gas inlet pressure. This is because the linear compressor 100 is constructed so that the differential pressure becomes 0 under the state where the inlet valve is open. In this state, a force from the pressure of the cooling medium gas onto the piston can be ignored. That is, in this state, the forces acting on the piston are only the repulsive force of the spring that is generated by the bending (deformation) of the support spring 81, and the electromagnetic force that is generated by applying a current to the linear motor. According to the Newton""s law of motion, the sum of these forces is equal to the product of the total mass of the movable member that is moving and its acceleration.
Accordingly, under this state, the following formula (3) holds as an equation of motion relating to the movable member.
m=a=xcex1xc3x97Ixe2x88x92k(xxe2x80x2+xavxe2x80x3xe2x88x92xinixe2x80x3)xe2x80x83xe2x80x83(3)
In formula (3), m is the total mass [kg] of the movable member that is reciprocating, a is the instantaneous acceleration [m/s2] of the movable member, and k is the spring constant [N/m] of the support spring that is incorporated in the linear compressor. Further, xavxe2x80x3 is the above-mentioned displacement on the third coordinate system Xxe2x80x3, which indicates the piston amplitude center position, and the absolute value of this displacement xavxe2x80x3 expresses the distance from the cylinder head position Psh to the piston amplitude center position pav. Further, xinixe2x80x3 is the displacement on the third coordinate system Xxe2x80x3, which indicates the piston neutral position Pini, and the absolute value of this displacement xinixe2x80x3 expresses the distance [m] between the piston neutral position (the position of the piston in the state where the support spring is not deformed) Pini and the cylinder head position Psh.
The instantaneous acceleration a[m/s2] is obtained as shown in the following formula (4) by differentiating the instantaneous velocity v[m/s] expressed by formula (1).                     a        =                              ⅆ            v                                ⅆ            t                                              (        4        )
Furthermore, the displacement xxe2x80x2[m] on the second coordinate system Xxe2x80x2, which indicates the distance from the piston amplitude center position Pav to the piston front end position P, is obtained by setting the constant Const. in formula (2) at 0.
Furthermore, the total mass m[kg] of the movable member, the spring constant k[N/m] of the support spring, and the displacement xinixe2x80x3 on the third coordinate system Xxe2x80x3, which indicates the distance from the cylinder head position Psh to the piston neutral position Pini, are already known values, and the driving current I may be the measured value.
Accordingly, the displacement xavxe2x80x3 on the third coordinate system Xxe2x80x3, which indicates the distance from the cylinder head position Psh to the piston amplitude center position Pav, can be calculated using formula (3).
Further, the displacement xtdxe2x80x3[m] on the third coordinate system Xxe2x80x3, which indicates the top dead point position of the piston (the position where the piston is closest to the cylinder head), can be obtained as a displacement in a position which is apart from the displacement xavxe2x80x3 on the third coordinate system Xxe2x80x3 obtained by formula (3) (the distance from the cylinder head position Psh to the piston amplitude center position Pav) by a distance that is equal to half of (Lps/2) the already-obtained piston stroke length Lps[m] toward the cylinder head.
In this way, the piston stroke length Lps[m] and the displacement xtdxe2x80x3[m] on the third coordinate system Xxe2x80x3, which indicates the piston top dead point position Ptd as a distance from the cylinder head position Psh, are calculated from the current I and voltage V which are applied to the linear compressor.
However, in the piston position detection method of the conventional linear compressor 100, since the piston displacement xxe2x80x2, which relatively indicates the piston position P with reference to the piston amplitude center position Pav, is calculated using the integrator and the differentiator, it is not possible to detect the piston position with high accuracy. That is, when the actual integrator and differentiator are constituted by analog circuits, ideal operations cannot be expected because of variations in parts, variations in characteristics due to temperature, and the like. On the other hand, when the integrator and differentiator are constituted by digital circuits, ideal operations cannot be expected because of the absence of data in sampling and holding.
Furthermore, when the piston position detecting circuit in the linear compressor is constituted by digital circuits, it is conceivable that the measuring cycle of the current I and the voltage V applied to the linear compressor may be reduced to increase the position detection accuracy. However, when the measuring cycle is reduced, the calculation cycle is also reduced, whereby the arithmetic load in the digital circuit is increased. Accordingly, when the measuring cycle is reduced, the performance of the microcomputer constituting the digital arithmetic circuit must be enhanced.
The present invention is made to solve the above-described problems and its object is to provide a linear compressor driving apparatus which can detect the position of a piston with high accuracy, on the basis of measured values of a driving current and a driving voltage applied to a linear compressor, without increasing loads of arithmetic processing using these measured values.
A linear compressor driving apparatus according to a first aspect of the present invention is a linear compressor driving apparatus for driving a linear compressor which has a piston and a linear motor for making the piston reciprocate and which generates a compressed gas by the reciprocating motion of the piston with an AC voltage being applied to the linear motor. The linear compressor apparatus according to the first aspect of the present invention comprises: an inverter for outputting an AC voltage and an AC current to the linear motor; a resonance frequency information output means for outputting resonance frequency information which indicates a resonance frequency of the reciprocating motion of the piston; a voltage detection means for detecting an output voltage of the inverter to output a voltage detection signal; a current detection means for detecting an output current of the inverter to output a current detection signal; an inverter controller for controlling the inverter on the basis of the resonance frequency information so that the inverter outputs, as an output voltage and output current, a sinusoidal-wave-shaped voltage and a sinusoidal-wave-shaped current whose frequencies match the resonance frequency of the piston reciprocating motion, respectively; a timing detection means for detecting, as a specific phase timing, a phase timing at which a differentiated value of the output current of the inverter becomes zero; and a piston velocity calculation means for receiving the voltage detection signal and the current detection signal, and calculating a maximum amplitude of a piston velocity in the piston reciprocating motion on the basis of instantaneous values of the output voltage and the output current from the inverter at the specific phase timing.
According to a second aspect of the present invention, in accordance with the linear compressor driving apparatus of the first aspect, the timing detection means detects, as the specific phase timing, a phase timing at which the amplitude of the output current from the inverter becomes maximum.
According to a third aspect of the present invention, in accordance with the linear compressor driving apparatus of the first aspect, the timing detection means detects a phase timing at which the phase of the output AC current from the inverter becomes at least one of 90xc2x0 and 270xc2x0, as the specific phase timing, on the basis of the current detection signal.
According to a fourth aspect of the present invention, in accordance with the linear compressor driving apparatus of the third aspect, the inverter is provided with an inverter controller for outputting an inverter driving control signal which drives and controls the inverter; and the timing detection means detects a phase timing at which a differentiated value of the output current from the inverter becomes zero on the basis of the phase of the inverter driving control signal.
According to a fifth aspect of the present invention, in accordance with the linear compressor driving apparatus of the fourth aspect, the timing detection means has a phase shift amount detector for detecting the amount of phase shift of the phase of the inverter driving control signal from the phase of the output current of the inverter, and detects a phase timing at which a differentiated value of the output current of the inverter becomes zero, on the basis of the inverter driving control signal whose phase is corrected so that the amount of phase shift becomes zero.
According to a sixth aspect of the present invention, in the linear compressor driving apparatus of the first apparatus, the piston velocity calculation means performs a temperature correction process on a thrust constant of the linear motor, whose value varies with variations in temperature, and calculates a maximum amplitude of the piston velocity on the basis of the temperature-corrected thrust constant, the instantaneous current value, the instantaneous voltage value, and an internal resistance value of the linear motor.
According to a seventh aspect of the present invention, in accordance with the linear compressor driving apparatus of the first aspect, the piston velocity calculation means performs a temperature correction process on an internal resistance value of the linear motor, whose value varies with variations in temperature, and calculates a maximum amplitude of the piston velocity on the basis of the temperature-corrected internal resistance value, the instantaneous values of the output voltage and output current of the inverter, and a thrust constant of the linear motor.
According to an eighth aspect of the present invention, in accordance with the linear compressor driving apparatus of the first aspect, the piston velocity calculation means repeats a velocity calculation process for calculating a maximum amplitude of the piston velocity, and in each of the repeated velocity calculation processes, the piston velocity calculation means corrects a thrust constant of the linear motor, whose value varies with variations in the piston velocity, on the basis of a maximum amplitude of the piston velocity which is calculated in a previous velocity calculation process, and calculates a maximum amplitude of the piston velocity on the basis of the corrected thrust constant.
According to a ninth aspect of the present invention, the linear compressor driving apparatus of the first aspect further includes a stroke information calculation means for calculating piston stroke information which indicates a maximum amplitude of a piston displacement in the piston reciprocating motion on the basis of the output voltage of the inverter and the frequency of the output current of the inverter, which are determined by the inverter controller, and the maximum amplitude of the piston velocity that is calculated by the piston velocity calculation means.
According to a tenth aspect of the present invention, the linear compressor driving apparatus of the first aspect further includes a bottom dead point position information calculation means for calculating bottom dead point position information which indicates a piston bottom dead point position in the piston reciprocating motion on the basis of the output voltage of the inverter and the frequency of the output current of the inverter, which are determined by the inverter controller, and the maximum amplitude of the piston velocity that is calculated by the piston velocity calculation means.
According to an eleventh aspect of the present invention, the linear compressor driving apparatus of the ninth aspect further includes: a bottom dead point position information calculation means for calculating bottom dead point position information which indicates a piston bottom dead point position in the piston reciprocating motion on the basis of the output voltage of the inverter and the frequency of the output current of the inverter, which are determined by the inverter controller, and the maximum amplitude of the piston velocity that is calculated by the piston velocity calculation means; and an arithmetic means for calculating center position information which indicates a piston center position in the piston reciprocating motion by performing the four fundamental rules of arithmetic on the basis of the bottom dead point position information and the piston stroke information.
According to a twelfth aspect of the present invention, the linear compressor driving apparatus of the ninth aspect further includes: a bottom dead point position information calculation means for calculating bottom dead point position information which indicates a piston bottom dead point position in the piston reciprocating motion, on the basis of the output voltage of the inverter and the frequency of the output current of the inverter, which are determined by the inverter controller, and the maximum amplitude of the piston velocity which is calculated by the piston velocity calculation means; and an arithmetic means for calculating top dead point position information indicating a piston top dead point position in the piston reciprocating motion by performing the four fundamental rules of arithmetic on the basis of the bottom dead point position information and the piston stroke information.
According to a thirteenth aspect of the present invention, the linear compressor driving apparatus of the ninth aspect further includes: a top dead point position information detection sensor for detecting a piston top dead point position in the piston reciprocating motion to output top dead point position information indicating the detected position; and an arithmetic means for calculating center position information indicating a piston center position in the piston reciprocating motion by performing the four fundamental rules of arithmetic on the basis of the top dead point position information and the piston stroke information.
According to a fourteenth aspect of the present invention, the linear compressor driving apparatus of the ninth aspect further includes: a top dead point position information detection sensor for detecting a piston top dead point position in the piston reciprocating motion to output top dead point position information indicating the detected position; and an arithmetic means for calculating bottom dead point position information indicating a piston bottom dead point position in the piston reciprocating motion by performing the four fundamental rules of arithmetic on the basis of the top dead point position information and the piston stroke information.
According to a fifteenth aspect of the present invention, the linear compressor driving apparatus of the ninth aspect further includes: a bottom dead point position information detection sensor for detecting a piston bottom dead point position in the piston reciprocating motion; and an arithmetic means for calculating center position information indicating a piston center position in the piston reciprocating motion by performing the four fundamental rules of arithmetic on the basis of the bottom dead point position information and the piston stroke information.
According to a sixteenth aspect of the present invention, the linear compressor driving apparatus of the ninth aspect further includes: a bottom dead point position information detection sensor for detecting a piston bottom dead point position in the piston reciprocating motion to output bottom dead point position information indicating the detected position; and an arithmetic means for calculating top dead point position information indicating a piston top dead point position in the piston reciprocating motion by performing the four fundamental rules of arithmetic on the basis of the bottom dead point position information and the piston stroke information.
According to a seventeenth aspect of the present invention, the linear compressor driving apparatus of the ninth aspect further includes: a center position information calculation means for calculating center position information indicating a piston center position in the piston reciprocating motion on the basis of the output current from the inverter; and an arithmetic means for calculating top dead point position information indicating a piston top dead point position in the piston reciprocating motion by performing the four fundamental rules of arithmetic on the basis of the center position information and the piston stroke information.
According to an eighteenth aspect of the present invention, the linear compressor driving apparatus of the ninth aspect further includes: a center position information calculation means for calculating center position information indicating a piston center position in the piston reciprocating motion on the basis of the output current from the inverter; and an arithmetic means for calculating bottom deal point position information indicating a piston bottom dead point position in the piston reciprocating motion by performing the four fundamental rules of arithmetic on the basis of the center position information and the piston stroke information.
According to a nineteenth aspect of the present invention, in accordance with the linear compressor driving apparatus of either the tenth through twelfth aspects, the linear compressor has an elastic member which applies a force to the piston so as to bring the piston back to its neutral position when the piston is displaced from the neutral position; and the bottom dead point position information calculation means calculates, as the bottom dead point position information, position information indicating the piston bottom dead point position relative to the piston neutral position on the basis of the output voltage of the inverter and the frequency of the output current of the inverter, which are determined by the inverter controller, the maximum amplitude of the piston velocity which is calculated by the piston velocity calculation means, the weight of the movable member which performs the piston reciprocating motion in the linear compressor, and the spring constant of the elastic member.
According to a twentieth aspect of the present invention, in the linear compressor driving apparatus of the ninth aspect, the piston stroke calculation means repeats a calculation process for calculating the piston stroke information on the basis of the maximum amplitude of the piston velocity, where in each of the repeated calculation processes, the piston stroke calculation means corrects a thrust constant of the linear motor, whose value varies with variations in the piston position, on the basis of the piston stroke information calculated in a previous calculation process, and calculates the piston stroke information on the basis of the corrected thrust constant.
A linear compressor driving apparatus according to a twenty-first aspect of the present invention is a linear compressor driving apparatus for driving a linear compressor which has a piston and a linear motor for reciprocating the piston and which generates a compressed gas by the reciprocating motion of the piston with an AC voltage being applied to the linear motor. The linear compressor driving apparatus according to the twenty-first aspect comprises: an inverter for outputting an AC voltage and an AC current to the linear motor; a resonance frequency information output means for outputting resonance frequency information that indicates a resonance frequency of the piston reciprocating motion; a current detection means for detecting an output current of the inverter to output a current detection signal; an inverter controller for controller the inverter on the basis of the resonance frequency information so that the inverter outputs, as an output voltage and output current, a sinusoidal-wave-shaped voltage and a sinusoidal-wave-shaped current whose frequencies match the resonance frequency of the piston reciprocating motion, respectively; a timing detection means for detecting, as a specific phase timing, a phase timing at which a differentiated value of the output current of the inverter becomes zero; and a piston center position calculation means for calculating position information indicating a piston center position in the piston reciprocating motion on the basis of an instantaneous value of the output current of the inverter at the specific phase timing, with reference to a piston position where a pressure difference between the pressure of a cooling medium gas that is discharged from the linear compressor and the pressure of the cooling medium gas that is drawn into the linear compressor becomes zero.
According to a twenty-second aspect of the present invention, in the linear compressor driving apparatus of the twenty-first aspect, the linear compressor has an elastic member which applies a force to the piston so as to bring the piston back to its neutral position when the piston is displaced from the neutral position; and the center position information calculation means calculates, as the center position information, position information indicating the piston center position relative to the piston neutral position on the basis of the maximum amplitude of the output current from the inverter, the thrust constant of the linear motor, and the spring constant of the elastic member.
According to a twenty-third aspect of the present invention, the linear compressor driving apparatus of the twenty-first aspect further includes: a discharge pressure detection means for detecting the pressure of the cooling medium gas that is discharged from the linear compressor; and an inlet pressure detection means for detecting the pressure of the cooling medium gas that is drawn into the linear compressor; wherein the center position information calculation means calculates an action force in the direction of the piston reciprocating motion, which force acts on the piston from the cooling medium gas, on the basis of the pressure difference between the discharge pressure and the inlet pressure, and then calculates, as the center position information, position information indicating the piston center position relative to the piston position where the pressure difference becomes zero, on the basis of the calculated action force.
According to a twenty-fourth aspect of the present invention, in accordance with the linear compressor driving apparatus of the twenty-third aspect, the center position information calculation means calculates an action force in the direction of the piston reciprocating motion, which force acts on the piston from the cooling medium gas, on the basis of the pressure difference between the discharge pressure and the inlet pressure and the resonance frequency indicated by the resonance frequency information, and then calculates, as the center position information, position information indicating the piston center position relative to the piston position where the pressure difference becomes zero on the basis of the calculated action force.
As described above, according to the first aspect of the present invention, there is provided a linear compressor driving apparatus for driving a linear compressor which has a piston and a linear motor for making the piston reciprocate, and generates a compressed gas by the reciprocating motion of the piston, with an AC voltage being applied to the linear motor, and this apparatus comprises: an inverter for outputting an AC voltage and an AC current to the linear motor; a resonance frequency information output means for outputting resonance frequency information which indicates a resonance frequency of the reciprocating motion of the piston; a voltage detection means for detecting an output voltage of the inverter to output a voltage detection signal; a current detection means for detecting an output current of the inverter to output a current detection signal; an inverter controller for controlling the inverter on the basis of the resonance frequency information so that the inverter outputs, as the output voltage and output current of the inverter, a sinusoidal-wave-shaped voltage and a sinusoidal-wave-shaped current whose frequencies match the resonance frequency of the piston reciprocating motion, respectively; a timing detection means for detecting, as a specific phase timing, a phase timing at which a differentiated value of the output current of the inverter becomes zero; and a piston velocity calculation means for receiving the voltage detection signal and the current detection signal, and calculating a maximum amplitude of a piston velocity in the piston reciprocating motion on the basis of instantaneous values of the output voltage and the output current from the inverter at the specific phase timing. Therefore, a displacement of the piston can be easily and accurately obtained on the basis of the driving current and driving voltage of the linear compressor without having to use complicated calculations such as integration and differentiation.
According to the second aspect of the present invention, in accordance with the linear compressor driving apparatus of the first aspect, the timing detection means detects, as the specific phase timing, a phase timing at which the amplitude of the output current from the inverter becomes maximum. Therefore, in an arithmetic formula for calculating the piston velocity from the driving current and driving voltage of the linear compressor, a term including the differentiated value of the driving-current can be deleted as being zero.
According to the third aspect of present invention, in accordance with the linear compressor driving apparatus of the first aspect, the timing detection means detects a phase timing at which the phase of the output AC current from the inverter becomes at least one of 90xc2x0 and 270xc2x0, as the specific phase timing, on the basis of the current detection signal. Therefore, in an arithmetic formula for calculating the piston velocity from the driving current and the driving voltage of the linear compressor, a term including the differentiated value of the driving current can be deleted as being zero.
According to the fourth aspect of the present invention, in accordance with the linear compressor driving apparatus of the third aspect, the inverter is provided with an inverter controller for outputting an inverter driving control signal which drives and controls the inverter; and the timing detection means detects a phase timing at which a differentiated value of the output current from the inverter becomes zero on the basis of the phase of the inverter driving control signal. Therefore, in an arithmetic formula for calculating the piston velocity from the driving current and driving voltage of the linear compressor, a term including the differentiated value of the driving current can be deleted.
According to the fifth aspect of the present invention, in accordance with the linear compressor driving apparatus of the fourth aspect, the timing detection means has a phase shift amount detector for detecting the amount of phase shift of the phase of the inverter driving control signal from the phase of the output current of the inverter, and detects a phase timing at which a differentiated value of the output current of the inverter becomes zero, on the basis of the inverter driving control signal whose phase is corrected so that the amount of phase shift becomes zero. Therefore, a phase timing at which the differentiated value of the output current of the inverter becomes zero can be correctly detected on the basis of the inverter driving control signal.
According to the sixth aspect of the present invention, in accordance with the linear compressor driving apparatus of the first aspect, the piston velocity calculation means performs a temperature correction process on a thrust constant of the linear motor, whose value varies with variations in temperature, and calculates a maximum amplitude of the piston velocity on the basis of the temperature-corrected thrust constant, the instantaneous current value, the instantaneous voltage value, and an internal resistance value of the linear motor. Therefore, the maximum amplitude of the piston velocity can always be detected with accuracy, irregardless of variations in the thrust constant of the linear motor due to variations in the temperature of the linear compressor.
According to the seventh aspect of the present invention, in accordance with the linear compressor driving apparatus of the first aspect, the piston velocity calculation means performs a temperature correction process on an internal resistance value of the linear motor, whose value varies with variations in temperature, and calculates a maximum amplitude of the piston velocity on the basis of the temperature-corrected internal resistance value, the instantaneous values of the output voltage and output current of the inverter, and a thrust constant of the linear motor. Therefore, the maximum amplitude of the piston velocity can always be detected with accuracy, irregardless of variations in the internal resistance value of the linear motor due to variations in the temperature of the linear compressor.
According to the eighth aspect of the present invention, in accordance with the linear compressor driving apparatus of the first aspect, the piston velocity calculation means repeats a velocity calculation process for calculating a maximum amplitude of the piston velocity, and in each of the repeated velocity calculation processes, the piston velocity calculation means corrects a thrust constant of the linear motor, whose value varies with variations in the piston velocity, on the basis of a maximum amplitude of the piston velocity which is calculated in the previous velocity calculation process, and calculates a maximum amplitude of the piston velocity on the basis of the corrected thrust constant. Therefore, the maximum amplitude of the piston velocity can always be detected with accuracy, irregardless of variations in the thrust constant of the linear motor due to variations in the piston velocity.
According to the ninth aspect of the present invention, the linear compressor driving apparatus of the first aspect further includes a stroke information calculation means for calculating piston stroke information which indicates a maximum amplitude of a piston displacement in the piston reciprocating motion on the basis of the output voltage of the inverter and the frequency of the output current of the inverter, which are determined by the inverter controller, and the maximum amplitude of the piston velocity that is calculated by the piston velocity calculation means. Therefore, the driving ability of the linear compressor can be controlled on the basis of the piston stroke information.
According to the tenth aspect of the present invention, the linear compressor driving apparatus of the first aspect further includes a bottom dead point position information calculation means for calculating bottom dead point position information which indicates a piston bottom dead point position in the piston reciprocating motion on the basis of the output voltage of the inverter and the frequency of the output current of the inverter, which are determined by the inverter controller, and the maximum amplitude of the piston velocity that is calculated by the piston velocity calculation means. Therefore, the amount of flexure of the resonance spring can be grasped according to the piston bottom dead point position information. Thereby, driving control of the linear compressor can also be carried out on the basis of the amount of flexure of the resonance spring so that the resonance spring is not deformed beyond its destruction limits.
According to the eleventh aspect of the present invention, the linear compressor driving apparatus in the ninth aspect further includes: a bottom dead point position information calculation means for calculating bottom dead point position information which indicates a piston bottom dead point position in the piston reciprocating motion on the basis of the output voltage of the inverter and the frequency of the output current of the inverter, which are determined by the inverter controller, and the maximum amplitude of the piston velocity that is calculated by the piston velocity calculation means; and an arithmetic means for calculating center position information which indicates a piston center position in the piston reciprocating motion by performing the four fundamental rules of arithmetic on the basis of the bottom dead point position information and the piston stroke information. Therefore, the linear compressor can be controlled on the basis of the piston center position information so that the piston vibration center position matches the position where the maximum efficiency of the linear motor can be achieved, whereby the linear compressor driving efficiency can be further enhanced.
According to the twelfth aspect of the present invention, the linear compressor driving apparatus of the ninth aspect further includes: a bottom dead point position information calculation means for calculating bottom dead point position information which indicates a piston bottom dead point position in the piston reciprocating motion on the basis of the output voltage of the inverter and the frequency of the output current of the inverter, which are determined by the inverter controller, and the maximum amplitude of the piston velocity which is calculated by the piston velocity calculation means; and an arithmetic means for calculating top dead point position information indicating a piston top dead point position in the piston reciprocating motion by performing the four fundamental rules of arithmetic on the basis of the bottom dead point position information and the piston stroke information. Therefore, the possibility of collision between the piston and the cylinder head can be judged with high accuracy on the basis of the top dead point position information.
According to the thirteenth aspect of the present invention, the linear compressor driving apparatus of the ninth aspect further includes: a top dead point position information detection sensor for detecting a piston top dead point position in the piston reciprocating motion to output top dead point position information indicating the detected position; and an arithmetic means for calculating center position information indicating a piston center position in the piston reciprocating motion by performing the four fundamental rules of arithmetic on the basis of the top dead point position information and the piston stroke information. Therefore, the linear compressor can be controlled by using a simple sensor so that the piston vibration center position matches the position where the maximum efficiency of the linear motor can be achieved, whereby the linear compressor driving efficiency can be further enhanced.
According to the fourteenth aspect of the present invention, the linear compressor driving apparatus of the ninth aspect further includes: a top dead point position information detection sensor for detecting a piston top dead point position in the piston reciprocating motion to output top dead point position information indicating the detected position; and an arithmetic means for calculating bottom dead point position information indicating a piston bottom dead point position in the piston reciprocating motion by performing the four fundamental rules of arithmetic on the basis of the top dead point position information and the piston stroke information. Therefore, the linear compressor can be controlled by using a simple sensor so that the resonance spring is not deformed beyond the destruction limits on the basis of the piston bottom dead point position information.
According to the fifteenth aspect of the present invention, the linear compressor driving apparatus of the ninth aspect further includes: a bottom dead point position information detection sensor for detecting a piston bottom dead point position in the piston reciprocating motion; and an arithmetic means for calculating center position information indicating a piston center position in the piston reciprocating motion by performing the four fundamental rules of arithmetic on the basis of the bottom dead point position information and the piston stroke information. Therefore, the linear compressor can be controlled by using a simple sensor so that the piston vibration center position matches the position where the maximum efficiency of the linear motor can be achieved, whereby the linear compressor driving efficiency can be further enhanced.
According to the sixteenth aspect of the present invention, the linear compressor driving apparatus of the ninth aspect further includes: a bottom dead point position information detection sensor for detecting a piston bottom dead point position in the piston reciprocating motion to output bottom dead point position information indicating the detected position; and an arithmetic means for calculating top dead point position information indicating a piston top dead point position in the piston reciprocating motion by performing the four fundamental rules of arithmetic on the basis of the bottom dead point position information and the piston stroke information. Therefore, by using a simple sensor the risk of collision between the piston and the cylinder head can be judged on the basis of the top dead point position information.
According to the seventeenth aspect of the present invention , the linear compressor driving apparatus of the ninth aspect further includes: a center position information calculation means for calculating center position information indicating a piston center position in the piston reciprocating motion on the basis of the output current from the inverter; and an arithmetic means for calculating top dead point position information indicating a piston top dead point position in the piston reciprocating motion, by performing the four fundamental rules of arithmetic on the basis of the center position information and the piston stroke information. Therefore, the possibility of collision between the piston and the cylinder head can be judged with high accuracy on the basis of the top dead point position information.
According to the eighteenth aspect of the present invention, the linear compressor driving apparatus of the ninth aspect further includes: a center position information calculation means for calculating center position information indicating a piston center position in the piston reciprocating motion on the basis of the output current from the inverter; and an arithmetic means for calculating bottom deal point position information indicating a piston bottom dead point position in the piston reciprocating motion by performing the four fundamental rules of arithmetic on the basis of the center position information and the piston stroke information. Therefore, driving control of the linear compressor can also be carried out so that the resonance spring is not compressed beyond the destruction limits, on the basis of the piston bottom dead point position information.
According to the nineteenth aspect of the present invention, in accordance with the linear compressor driving apparatus of any of the tenth through twelfth aspects, the linear compressor has an elastic member which applies a force to the piston so as to bring the piston back to its neutral position when the piston is displaced from the neutral position; and the bottom dead point position information calculation means calculates, as the bottom dead point position information, position information indicating the piston bottom dead point position relative to the piston neutral position on the basis of the output voltage of the inverter and the frequency of the output current of the inverter, which are determined by the inverter controller, the maximum amplitude of the piston velocity which is calculated by the piston velocity calculation means, the weight of the movable member which performs the piston reciprocating motion in the linear compressor, and the spring constant of the elastic member. Therefore, the amount of flexure of the resonance spring can be determined according to the piston bottom dead point position information. Thereby, driving control of the linear compressor so as to prevent the resonance spring from being deformed beyond the destruction limits can be easily carried out on the basis of the amount of flexure of the resonance spring.
According to the twentieth aspect of the present invention, in accordance with the linear compressor driving apparatus of the ninth aspect, the piston stroke calculation means repeats a calculation process for calculating the piston stroke information on the basis of the maximum amplitude of the piston velocity, where in each of the repeated calculation processes, the piston stroke calculation means corrects a thrust constant of the linear motor, whose value varies with variations in the piston position, on the basis of the piston stroke information calculated in the previous calculation process, and calculates the piston stroke information on the basis of the corrected thrust constant. Therefore, the maximum amplitude of the piston velocity can always be detected with accuracy, irregardless of variations in the thrust constant of the linear motor due to variations in the piston position.
According to the twenty-first aspect of the present invention, there is provided a linear compressor driving apparatus for driving a linear compressor which has a piston and a linear motor for reciprocating the piston, and generates a compressed gas by the reciprocating motion of the piston, with an AC voltage being applied to the linear motor, and this apparatus comprises: an inverter for outputting an AC voltage and an AC current to the linear motor; a resonance frequency information output means for outputting resonance frequency information that indicates a resonance frequency of the piston reciprocating motion; a current detection means for detecting an output current of the inverter to output a current detection signal; an inverter controller for controller the inverter on the basis of the resonance frequency information so that the inverter outputs, as its output voltage and output current, a sinusoidal-wave-shaped voltage and a sinusoidal-wave-shaped current whose frequencies match the resonance frequency of the piston reciprocating motion, respectively; a timing detection means for detecting, as a specific phase timing, a phase timing at which a differentiated value of the output current of the inverter becomes zero; and a piston center position calculation means for calculating position information indicating a piston center position in the piston reciprocating motion on the basis of an instantaneous value of the output current of the inverter at the specific phase timing, with reference to a piston position where a pressure difference between the pressure of a cooling medium gas that is discharged from the linear compressor and the pressure of the cooling medium gas that is drawn into the linear compressor becomes zero. Therefore, the linear compressor can be controlled on the basis of the piston center position information so that the piston vibration center position matches the position where the maximum efficiency of the linear motor can be achieved, whereby the linear compressor driving efficiency can be further enhanced.
According to the twenty-second aspect of the present invention, in accordance with the linear compressor driving apparatus of the twenty-first aspect, the linear compressor has an elastic member which applies a force to the piston so as to bring the piston back to its neutral position, when the piston is displaced from the neutral position; and the center position information calculation means calculates, as the center position information, position information indicating the piston center position relative to the piston neutral position, on the basis of the maximum amplitude of the output current from the inverter, the thrust constant of the linear motor, and the spring constant of the elastic member. Therefore, the linear compressor can be controlled on the basis of the piston center position information so that the piston vibration center position matches the position where the maximum efficiency of the linear motor can be achieved, whereby the linear compressor driving efficiency can be further enhanced.
According to the twenty-third aspect of the present invention, the linear compressor driving apparatus of the twenty-first aspect further includes: a discharge pressure detection means for detecting the pressure of the cooling medium gas that is discharged from the linear compressor; and an inlet pressure detection means for detecting the pressure of the cooling medium gas that is drawn into the linear compressor; wherein the center position information calculation means calculates an action force in the direction of the piston reciprocating motion, which force acts on the piston from the cooling medium gas, on the basis of the pressure difference between the discharge pressure and the inlet pressure, and then calculates, as the center position information, position information indicating the piston center position relative to the piston position where the pressure difference becomes zero, on the basis of the calculated action force. Therefore, the linear compressor can be controlled on the basis of the piston center position information so that the piston vibration center position matches the position where the maximum efficiency of the linear motor can be achieved, whereby the linear compressor driving efficiency can be further enhanced.
According to the twenty-fourth aspect of the present invention, in accordance with the linear compressor driving apparatus of the twenty-third aspect, the center position information calculation means calculates an action force in the direction of the piston reciprocating motion, which force acts on the piston from the cooling medium gas, on the basis of the pressure difference between the discharge pressure and the inlet pressure, and the resonance frequency indicated by the resonance frequency information, and then calculates, as the center position information, position information indicating the piston center position relative to the piston position where the pressure difference becomes zero on the basis of the calculated action force. Therefore, the linear compressor can be controlled on the basis of the piston center position information so that the piston vibration center position matches the position where the maximum efficiency of the linear motor can be achieved, whereby the linear compressor driving efficiency can be further enhanced.

Matsushita Electric Industrial Co., Ltd.


[Problem] Change the distribution logic flexibly.

Disclosed is a technology in which a load balancer (Balancer) distributes processing requests (packets) to a plurality of dispatchers, and the plurality of dispatchers distribute the distributed processing requests to the same number of servers (CPU) as the dispatchers, and the server to which the processing request is distributed executes processing (see Patent Literature 1). Patent Literature 1 also describes that "when the load balancer B acquires a processing request from the external apparatus 5, the load balancer B distributes the processing request to one of the plurality of dispatchers D (D1, D2, and D3) in a round-robin fashion".

Abstract: [Solution] A control apparatus includes a communication unit (NIC20) configured to receive a packet from a network, a plurality of first control units (3a, 3b, 3c, 3d) configured to function as a plurality of virtual control units (VM1a, 1b, 1c, . . . ), a distribution circuit (Balancer 10a) configured to distribute the received packet to a plurality of dispatchers, a plurality of second control units (Dispatcher 4a, 4b, 4c, and 4d) configured to distribute the packet distributed by the distribution circuit to the plurality of virtual control units (VM1a, 1b, 1c, . . . ), in which the distribution circuit is configured by a PLD.

Nippon Telegraph and Telephone Corporation


An exhaust heat utilization method for a carbon dioxide recovery process comprises heating returning hot water by at least one heat exchange selected from heat exchange with the regenerated absorbing liquid after heat exchange, heat exchange with carbon dioxide exhausted from the regeneration tower, and heat exchange with saturated water after heating the bottom of the regeneration tower, thereby obtaining hot water.

1. Field of the Invention
The present invention relates to an exhaust heat utilization method for a carbon dioxide recovery process.
2. Description of the Related Art
Conventionally, a large amount of exhaust heat generated in a process of recovering carbon dioxide from a combustion exhaust gas is cooled with cooling water. In a local area where a large amount of cooling water cannot be ensured, a large amount of exhaust heat is cooled using air cooling. Hence, a large amount of low-temperature exhaust heat is discarded without being utilized.
As a system for supplying hot water to a local, conventionally, one shown in FIG. 4 is employed in which heat generated by a power plant is utilized.
More specifically, steam of a boiler 101 is supplied to a steam turbine 102, so a generator 103 generates electricity. The steam is condensed by a condenser 104 and returned to the boiler 101 by a pump 105. The low-pressure steam is extracted from the steam turbine 102 and exchanges heat with water returned from local hot water by a heat exchanger 106. The returned local hot water is thus heated and provided as local hot water. The condensate obtained from the heat exchanged low-pressure steam is returned to the boiler 101 by a pump 107.
In the conventional local hot water system, since the low-pressure steam is extracted from the steam turbine 102, an output from the steam turbine 102 decreases. Consequently, the power generation amount decreases.
It is an object of the present invention to provide an exhaust heat utilization method for a carbon dioxide recovery process, with which returning hot water is heated by utilizing a large amount of exhaust heat generated in a process of recovering carbon dioxide from combustion exhaust gas, so a large amount of hot water to be supplied for local heating or the like can be obtained.
According to an aspect of the present invention, there is provided, an exhaust heat utilization method for a carbon dioxide recovery process, comprising:
providing a carbon dioxide recovery unit comprising a cooling tower, an absorption tower for absorbing a carbon dioxide with an absorbing liquid, and a regeneration tower for regenerating a absorbing liquid;
supplying a combustion exhaust gas to the cooling tower to cool the combustion exhaust gas;
supplying the cooled combustion exhaust gas to the absorption tower so as to come into contact with a regenerated absorbing liquid supplied from the regeneration tower to absorb carbon dioxide in the combustion exhaust gas with the regenerated absorbing liquid, thereby storing a carbon dioxide-absorbed absorbing liquid in a bottom of the absorption tower;
heating the carbon dioxide-absorbed absorbing liquid by heat exchange with the regenerated absorbing liquid supplied from the regeneration tower;
supplying the heated carbon dioxide-absorbed absorbing liquid to the regeneration tower;
heating the bottom of the regeneration tower using saturated steam to separate the carbon dioxide-absorbed absorbing liquid into carbon dioxide and a regenerated absorbing liquid; and
discharging and recovering separated carbon dioxide from the regeneration tower,
wherein returning hot water is heated by at least one heat exchange selected from heat exchange with the regenerated absorbing liquid after heat exchange, heat exchange with carbon dioxide exhausted from the regeneration tower, and heat exchange with saturated water after heating the bottom of the regeneration tower, thereby obtaining hot water.
In the exhaust heat utilization method for the carbon dioxide recovery process according to the present invention, as the combustion exhaust gas, use of one exhausted from a boiler or gas turbine of a power plant is allowed.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.

Exhaust heat utilization method for carbon dioxide recovery process


A gas-turbine power generating installation capable of effectively utilizing gases produced in overage gas fields, etc. and a method of operating the installation are provided. The gas-turbine power generating installation is installed in the vicinity of an outrage gas field or an oil field. In the installation, air compressed by a compressor is introduced to a combustor for combustion after being mixed with fuel, a gas turbine is driven by generated combustion gas, and a power generator is driven by motive power obtained from a rotary shaft of the gas turbine. A boosting compressor is driven by the motive power obtained from the rotary shaft of the gas turbine, whereby natural gas or accompanying gas is boosted in pressure and supplied as fuel to the combustor. The gas turbine generates electric power by using natural gas produced in the outrage gas field or accompanying gas produced in the oil field, and the generated electric power is supplied to a consuming site.

1. Field of the Invention
The present invention relates to a gas-turbine power generating installation and a method of operating the gas-turbine power generating installation. More particularly, the present invention relates to a gas-turbine power generating installation capable of employing gases produced in overage gas fields, etc., such as natural gas extracted from the overage gas fields at reduced outturn and low pressure, and accompanying gas produced at low pressure during oil extraction in oil fields, and also to a method of operating the gas-turbine power generating installation.
2. Description of the Related Art
In view of environment pollution in worldwide scale, regulations on exhaust gas from various engines have been urged in progress. Under such situations, natural gas is worthy of note as fuel giving less influence upon environments.
Natural gas NG is transported from a gas field GF to a consuming site, as shown in FIG. 1, by a method of liquefying the natural gas with liquefying equipment in the gas field and transporting the liquefied gas to the consuming site by land or sea, or a method of transporting the natural gas, as it is, to the consuming site through a pipeline PL. The pipeline includes several booster stations BS for boosting the pressure of natural gas to compensate for a pressure loss caused as the natural gas flows through the pipeline. The interval between the booster stations BS is, e.g., several tens to several hundreds kilometers. General constructions of known gas-turbine power generating installations are disclosed in, e.g., JP-A-2003-166428 and JP-A-2002-327629.

This patent is subject to a terminal disclaimer.

Gas-turbine power generating installation and method of operating the same


A prefabricated retaining wall structure and method of installing. The structure has a precast concrete face panel and an elongated support column permanently joined to the face panel. The face panel has a top and bottom, opposing end edges and first and second sides with a thickness therebetween. The elongated support column is secured to the face panel between the opposing end edges. The column has first and second ends and an elongated body therebetween and extends along a portion of the first side of the face panel.

In a conventional retaining wall design, one of the major design considerations is whether the existing terrain will require a cut into the existing ground or fill to create a higher elevation for a new structure such as a road or railway. There are several different retaining wall styles that fall into either deep or shallow foundation walls. In cut situations, typically a deep foundation wall such as a soldier pile retaining wall is preferred since the wall can be constructed with a minimal cut into the existing soil versus a shallow foundation wall such as a mechanically stabilized earth wall which requires a large excavation or cut into the existing ground for straps or ties which will then need to be backfilled with expensive select aggregate. These ties can also be a problem for future maintenance when there is limited space and the straps lie under a future road or railway.
Deep foundation systems generally provide an alternate solution which does not require tieback stabilizing features to oppose the lateral force of the soil. Thus, such systems can be highly advantageous where property lines or site conditions limit the horizontal footprint of the system. Such systems can also be especially useful where adverse soil conditions are near the surface or large loadings on the wall require more stable soil that is typically found at lower depths. Deep foundation systems typically consist of wall panels or laggings that span vertical columns (posts or piles) that can be either driven into the ground or embedded into concrete filled drilled holes. The columns can either cantilever out of the ground or can be anchored back with one or multiple tie rod(s) at various depths of the column. As the earth is filled along the back of the wall, the panels carry the load horizontally to the columns which extend vertically carrying the load deep into the ground and also into the anchors, when utilized.
As walls grow in height upwards of 15 feet, soldier pile walls become expensive due to the exponential nature of soldier pile design which requires huge steel rolled shapes to resist the large overturning moments due to the lateral forces from earth, wind, and/or vehicle surcharge amongst other forces. A composite design which ties the column to the face panel or lagging would reduce this cost. The installation of such known deep foundation post and panel retaining walls, however, is generally a time-consuming process that involves several steps, including for example, selecting a column spacing, determining the optimum length and diameter of the columns, embedding the columns into the holes and then subsequently returning to set the panels between the columns. In addition, the panels of such systems are typically designed as "simple spans" between the columns which must be lifted and moved into position and separately secured to the already installed exposed columns. Altogether, this process can be considerably labor-intensive and can increase the costs and installation time of retaining wall installation projects. Such disadvantages can in turn make deep foundation systems impractical and/or cost prohibitive.
Thus, in view of the foregoing, it would be extremely useful to have a deep foundation precast retaining wall system that can be easily installed and used in connection with a variety of locations and that is sufficiently robust to resist lateral pressures from the retained soil by utilizing multiple spans versus the conventional simple span. It would be further desirable if such structure could be economically fabricated and installed such that labor and material costs that are typically incurred in connection with retaining wall projects can be reduced, while also concealing the support columns for a cleaner aesthetic. From the following description, it will be recognized by persons of ordinary skill in the art that embodiments of the subject invention can provide such benefits as well as other objects, features of advantages.

Precast integral post and retaining wall and method for installing same


A display apparatus includes a light guide plate guiding a light, a light source arranged in a side portion of the light guide plate to generate the light, a display panel receiving the light from the light guide plate to display an image, a frame including a sidewall and a support part extended from the sidewall to support the display panel, and an optical member arranged between the light guide plate and the display panel to control a path of the light exiting from the light guide plate. The optical member includes a first side portion and a second side portion, a side surface of the first side portion faces a side surface of the support part, and the second side portion is positioned between the support part and the light guide plate.

1. Field of the Invention
The present invention relates to a backlight assembly and a display apparatus having the same. More particularly, a backlight assembly capable of being easily assembled and uniformly providing a light and a display apparatus having the backlight assembly are disclosed.
2. Description of the Related Art
In a display apparatus having a display area that displays an image and a peripheral area surrounding the display area to block a light, the size of the peripheral area of the display apparatus is reduced to increase the size of the display area relative to the total size of the display apparatus.
However, in the case of liquid crystal displays that utilize a light guide plate to guide light from a light source to a display panel, leakage light, which is light that travels to the display panel without passing through the light guide plate, can occur. As a width of the peripheral area is reduced, the amount of the leakage light increases, thereby causing deterioration in display quality of the liquid crystal display.

Backlight assembly and display apparatus having the same


An improved gerotor device is disclosed, usable as either a pump or a motor, of the type including a gerotor gear set (17), and a movable valve member which may have either purely rotary motion (55), or may have both orbital and rotational motion (127). The valve member defines two groups of valve ports (63,65; 163,165) communicating with an inlet port (57) and an outlet port (61). The movable valve member is in sliding, sealing valving action with and an adjacent stationary valve plate (19'; 119') which defines a set of stationary fluid passages (67a-67g; 167a-167i) which communicate with the gerotor volume chambers (29a-29g). The stationary valve plate, in accordance with the invention, also defines a plurality of secondary fluid passages (77a-77g; 177a-177i) each of which is diametrically opposite one of the primary fluid passages (67a-67g; 167a-167i). The primary and secondary fluid passages are interconnected by cut-out portions within the stationary valve plate, defining fluid passages (81a-81g; 181a-181i), thus effectively doubling the orifice area during valving action, and substantially reducing the no-load pressure drop when the device is being used as a motor, or substantially reducing the tendency toward cavitation when the device is used as a pump.

The present invention relates to rotary fluid pressure devices, and more particularly, to such devices which include an internal gear set and a pair of relatively movable valve members operable to communicate fluid to and from the gear set.
Although it should become apparent from the subsequent description that the invention may be useful with various types and configurations of rotary fluid pressure devices, including both pumps and motors, it is especially advantageous when used in a device including a gerotor gear set.
Fluid motors of the type utilizing a gerotor displacement mechanism to convert fluid pressure into a rotary output are especially suited for low-speed, high-torque applications. Typically, in fluid motors of this type, there are two relatively movable valve members, one of which is stationary and provides a fluid passage communicating with each of the volume chambers of the gerotor, while the other valve member rotates at the speed of rotation of the rotatable member of the gerotor gear set. Valving of the type described above is referred to as being "low-speed, commutating" valving, to distinguish it from the type of valving referred to as "high-speed" valving, wherein the rotatable valve member rotates at the orbit speed of the orbiting member of the gerotor set.
One of the important performance criteria in gerotor motors of the type having low-speed, commutating valving is the "no-load pressure drop", which is a measure of the mechanical efficiency of the motor. The no-load pressure drop is the difference between the pressure at the inlet port and the pressure at the outlet port which is required to rotate the output shaft of the motor, with "no load", or no resistance to rotation of the output shaft. In a sense, the no-load pressure drop may be considered a measure of the motor's resistance to fluid flow through the main flow path, from the inlet port through the valving, then through the gerotor, then back through the valving, and finally to the outlet port. The smaller the various fluid passages and ports, the greater the resistance or restriction to fluid flow, and the higher the no-load pressure drop.
Excessive no-load pressure drop has been a problem especially in gerotor motors of the type referred to as "disc valve" motors, such as is shown in U.S. Pat. Nos. 3,572,983 and 3,434,600, assigned to the assignee of the present invention and incorporated herein by reference. The term "disc valve" will be understood to refer to a device in which the stationary and rotary valve surfaces are both, flat, planar surfaces oriented transverse to the axis of rotation of the device. In disc valve motors, there is a rotary disc valve defining a plurality of valve ports (for example, 12 or more) in a relatively small area, thus limiting the size of the ports and the area of communication between the rotating ports and the adjacent stationary ports.
Related to the problem of no-load pressure drop is that typical disc valve gerotor motors have not commonly been used as pumps, because the relatively high restriction to fluid flow would cause cavitation to occur within the device, unless the inlet port is pressurized, such as by means of a charge pump.

Rotary fluid pressure device and improved stationary valve plate therefor


A system and method for recorded renewable energy certificates from power produced by small power generators is provided. An appliance can include a renewable energy source and electronics to monitor and control the charging of batteries in the appliance utilizing power from the renewable energy source. Power from the batteries can be utilized to power or charge external devices. The electronics also records the total power production from the renewable energy source and uploads transaction records to either an external device for transmission to a records server or uploads it directly to the records server itself. The records server compiles the transaction records and generates renewable energy certificates by aggregating the transaction records. Renewable energy certificates can be redeemed in exchange for real or virtual goods and services.

1. Field
Embodiments of the invention relate generally to management of solar energy systems and, in particular, to the generation of solar renewable energy certificates.
2. Discussion of related art.
Renewable Energy Certificates (RECs), which includes Solar Renewable Energy Credits (SRECs), are a form of Renewable Energy Certificate or Green tag utilized to reward the producers of renewable energy. RECs are available in states where a Renewable Portfolio Standard (RPS) exists with a specific allocation for solar energy. SREC programs, for example, provide a means for SRECs to be created on behalf of a solar panel owner and sold to state electric suppliers to meet the solar RPS requirement. Electric suppliers are then required to use the SREC program to show compliance with this part of the State's Renewable Portfolio Standard.
The SREC is separate from the value of the electricity itself and permits the owner or purchaser to claim the benefits of the clean energy production by effectively subsidizing the cost of the installed system. SRECs are designed to provide individuals and corporations with an economic incentive to investing in solar electric systems, which improve the electrical distribution grid. SRECs represent the renewable attributes from a solar facility and are typically bundled in minimum denominations of one megawatt hour of production. The additional income received from selling solar certificates increases the economic value of an investment in renewable energies. Instead of up-front subsidies from the state, solar system owners can recover their investment in the solar system by selling certificates to utilities.
In order to produce SRECs, a solar system must first be certified by state regulatory agencies, usually public service commissions or public utility commissions, and then registered with a trading platform. Once a solar system is certified with the state agency and registered with a trading platform, SRECs can be issued using either an estimate table or actual meter readings by the trading platform - depending upon state regulations. In some cases, smaller installations may be able to use estimates, while actual meter readings are required for large installations. One SREC is created for every megawatt hour of electricity produced from a qualified solar renewable energy generator.
In Pennsylvania, New Jersey, Delaware, Ohio, Maryland and the District of Columbia solar systems are registered with, and SRECs are issued by, PJM Environmental Information Services Generation Attribute Tracking System PJM-EIS GATS. The Western Renewable Energy Generation Information System (WREGIS) is an independent, renewable energy tracking system for the region covered by the Western Electricity Coordinating Council (WECC). WREGIS tracks renewable energy generation from units that register in the system using verifiable data and creates renewable energy certificates (RECs) for this generation. WREGIS Certificates can be used to verify compliance with state and provincial regulatory requirements and in voluntary market programs. PJM-EIS GATS and WREGIS are accreditation entities and ultimately they, or similar organizations, issue RECs.
Therefore, there is a need for solar components that better track power production in order to allow the generation of RECs.

Generation of renewable energy certificates from distributed producers


An electrical connector comprises an insulative body defining a number of passageways therein, a shield enclosing the body, a number of contacts received in corresponding passageways, and a polyswitch for preventing excessive current from damaging the connector. One of the contacts consists of first and second contact members. The first contact member is adapted for mating with a mating contact of a complementary connector and the second contact member is adapted for being soldered to a circuit board. The polyswitch is retained in a cavity formed in the insulative body and is securely sandwiched between the first and second contact members.

1. Field of the Invention
The present invention relates to an electrical connector, and particularly to an electrical connector with a polyswitch retained therein for preventing excessive current from damaging the connector.
2. Description of Prior Art
A resettable device is commonly used to protect against a current exceeding a rated operational value anticipated by an electronic device such as a monitor, a keyboard and a stand-alone hub. The resettable device may take various forms such as a fuse, a bimetal, a ceramic PTC device or a polymeric PTC device which can be a polyswitch. To prevent excessive current from damaging or destroying an electronic system such as a computer, the resettable device is conventionally mounted on a mother board and occupies a significant amount of space thereon. Since the efficient use of space on the mother board is extremely important due to the trend of miniaturization, removing the resettable device from the mother board to reduce the occupied space thereon is requisite.
Therefore, a long and unfilled need exists in the prior art for removing the resettable device from the mother board in promotion of miniaturization.


A hand held remote control unit includes a wireless signal transmitter configured to transmit a fixed frequency (tone) signal and a manually operated switch to selectively operate the transmitter to transmit the wireless tone signal. A toy has an appropriate wireless signal receiver and control circuit responsive to the tone signal that controls one or more electrically operated devices that can provide at least two different, electrically activated responses of the toy apparent to an observer. The control circuit provides a sequence of two or more different predetermined responses of the toy in response to sequential reception and loss of the tone signal, the sequence of responses being repeated after completion.

Various types of remotely controlled toy and wireless remote control unit combinations are known. Those in the remote control toy art are constantly challenged to devise the new toys and new ways of remotely operating those toys. The challenge at the high end is to provide the greatest number of separately remotely controlled capabilities and the finest level of operational control to most closely mimic the operation of a real thing (living or mechanical). The challenge at the low end is to minimize production costs while providing the most remotely controlled operating capabilities of the toy. Another challenge at the low end is to simplify control of a toy to enable younger children, in some cases even toddlers, to operate such toys themselves for their own amusement.
In the remote control toy vehicle art, one common solution to the challenges at the low end was to provide a motorized toy vehicle with a tone signal generating wireless remote control. Whenever the tone signal was generated by user depression of a button or other manual input device, the vehicle receiving the tone signal would move forward for as long as the tone signal was received. If one or more other, different responses was desired of the toy vehicle, like reverse operation or steering, the transmitter was configured to generate and the toy vehicle configured to decode a different control signal for each different operation Thus, for forward and reverse operation, two separate control signals had to be generated and decoded. If steering was added to forward and reverse operation, four separate control signals were required.
One innovation to provide propulsion and steering capability in a low end toy vehicle provided with a single reversible electric motor was "J steering" or "J turning". A single output drive from the motor was fed to wheels on opposite sides of the vehicle through separate drive shafts. One drive shaft/wheel combination was connected directly with the motor drive. The other was connected through a "slide" or planetary gear and an idler gear. When the motor was driven in a first, forward propelling direction, both wheels were driven in the same rotational direction on a common axis between the two wheels. When the motor was driven in an opposite direction, the direction of the first wheel was reversed but the slide or planetary gear was pushed out of engagement with the second wheel's axle and into engagement with the idler gear which was itself engaged with the second wheel's axle. The idler gear reversed the rotation between the planetary gear and the second wheel's axle, which caused the second wheel's axle to continue to rotate in the first (i.e. forward propelling) direction. Thus, the driven wheels were now driven in opposite directions causing the vehicle to turn while backing up. By controlling ratios of the various gears including the idler, the two powered wheels can be made to rotate at different RPMs and the vehicle made to follow a circular path while backing up. The vehicle could be driven forward in a relatively straight line. If it needed to turn, it would have to reverse itself along the circular path until pointing in the desired direction, at which point it could be commanded to drive forward again. While this simplified the design of the vehicle, two separate command signals for forward and reverse movement still had to be generated by the remote controller and decoded by the vehicle.
One recent combination intended to simplify the provision of forward and reverse operation in a low end, remotely controlled toy vehicle has been to provide the toy vehicle with an on-off switch, a wireless signal receiver and control circuitry. The control circuitry was configured to supply power to an electric motor propelling the toy vehicle in a first direction, preferably a reverse J turn, for as long as the on-off switch was on. The direction of power supplied to the motor was switch when a fixed frequency or "tone" control signal was received from the remote control unit, causing the vehicle to move forward in a straight line. This simplified the design of both the transmission/reception circuits as only a single tone signal needed to be generated and identified to control forward and reverse movement.
It was thought this simplified system might be improved in other ways.

Remotely controllable toy and wireless remote control unit combination