text:
|Publication number
|Publication type
|Application number
|Publication date
|May 1, 1979
|Filing date
|Jul 18, 1977
|Priority date
|May 9, 1977
|Publication number
|Kenneth J. Kountz, Richard A. Erth, Bruce K. Bauman
|Original Assignee
|Borg-Warner Corporation
|Export Citation
|BiBTeX, EndNote, RefMan
|Patent Citations (3), Referenced by (121), Classifications (21), Legal Events (5)
|External Links: USPTO, USPTO Assignment, Espacenet
This application is a continuation-in-part of applicants' earlier application of the same title filed May 9, 1977, with Ser. No. 794,884, now abandoned.
Large capacity air conditioning systems have used centrifugal compressors with guide vanes at the compressor inlet, which vanes are adjustable to regulate both the direction (or "swirl") of the incoming gas and also produce a pressure drop which is a function of the vane position. These vanes, sometimes termed pre-rotation vanes (PRV), are thus adjusted to vary the capacity of the compressor. In the condition of wide-open vanes (WOV) a small change in the vane position does not have a substantial effect on the compressor head or capacity. When the PRV are nearly closed a slight change has a very substantial effect on the compressor capacity, and could even send the compressor into surge if care is not taken in adjusting the vane position. Because capacity control solely by changing PRV position is an inefficient method of capacity control, there have been attempts to regulate system capacity only by governing the speed of the electrical motor driving the compressor. If speed control is utilized as the only means of regulating the capacity, the compressor can only be operated down to about 70% of its full load. This is economically impractical for large installations, since for substantial periods of time the load is below 70% of the full load value.
Accordingly various attempts have been made to combine adjustment of the PRV with regulation of the motor speed, which can successfuly reduce the load down to about 10% of full load. One significant early effort in this direction is taught in U.S. Pat. No. 3,355,906, entitled "Refrigeration System Inlcuding Control for Varying Compressor Speed", which issued Dec. 5, 1967, and is assigned to the assignee of this invention. In that arrangement the motor speed was adjusted as a function of the ratio between the compressor suction pressure and discharge pressure, and the PRV were adjusted in relation to a signal derived from the temperature of the heat exchange medium at the discharge of the evaporator. Most similar efforts since that time have used the pressure ratio of the compressor to regulate the motor speed, and derivation of this pressure information has proved difficult and expensive in practice. In addition it has been found that the regulation of the pre-rotation vanes is a complex function, which has not been effectively controlled to avoid surge and provide most efficient operation by sensing of only a single variable condition.
It is therefore a primary object of the present invention to provide a control system for regulating a refrigeration system, such as one including a centrifugal compressor, in which not only are the motor speed controlled and PRV position adjusted, but this speed control and vane adjustment are achieved over an optimum path of control with minimum energy expended.
A related important aspect of the invention is the provision of such a control system which achieves such energy effective system operation, and at the same time avoids surge.
Of prime importance is the provision of such a control system, which is not only capable of installation with new equipment, but is readily installed on existing systems to achieve the optimum control path while avoiding surge in those systems.
Still another important object of the invention is linearization of the PRV action, through a controller with a non-linear duty cycle to produce more uniform system control.
Another important object of the invention is to achieve such precise system operation over a wide load range without the necessity of sensing compressor pressures to derive the compressor head value.
The control system of the invention is useful to regulate a refrigeration system including a compressor, a condenser and an evaporator, all connected in a closed refrigeration circuit. Inlet guide vanes are positioned between the evaporator and the compressor to regulate the capacity of the compressor, and some means, such as an electrical motor, is connected to adjust the inlet guide vanes' position. Means, such as another electrical motor, drives the compressor. The control system of the invention is connected to regulate both the means for adjusting the guide vanes' position and the means for driving the compressor. A first temperature sensing means is positioned adjacent the condenser to provide a first signal related to the refrigerant condensing temperature, and a second sensing means is positioned in the evaporator to provide a second signal related to the refrigerant evaporating temperature. A summation means is connected to receive both the first and second signals, and to provide a resultant signal which connotes the head of the compressor. The control system uses the resultant signal to regulate the refrigeration system. A third temperature sensing means is positioned adjacent the chilled water discharge of the evaporator to provide a third signal. An adjustable means is provided in the control system for establishing a temperature set point signal. Means is also provided for combining the third signal and the temperature set point signal to produce another regulating signal, for use in controlling the refrigeration system.
In accordance with another aspect of the invention, an additional means is coupled to the inlet guide vanes for providing an electrical signal which indicates the physical position of the inlet guide vanes. Means is provided for combining the inlet guide vane position signal with the resultant signal to produce a regulating signal for use in system regulation.
In the several figures of the drawings, like reference numerals identify like components, and in those drawings:
FIG. 1 is a block diagram illustrating the incorporation of the control system of this invention into a cooling system which includes a centrifugal compressor;
FIGS. 2, 3 and 4 are graphical illustrations useful in understanding operation of the invention;
FIG. 5 is a diagram showing the principal signal paths in the control system of the invention;
FIGS. 6A, 6B and 6C are schematic diagrams which, taken together, illustrate the circuit details of the control system of this invention;
FIG. 7 is a graph depicting the relationship of compressor capacity to PRV opening for different head values;
FIGS. 8A-8F are graphical illustrations useful in explaining one aspect of the invention; and
FIG. 9 is a graph of compressor speed dependence on PRV position, for a fixed head value.
FIG. 1 depicts certain conventional components of a cooling system, such as a centrifugal compressor 20 for passing refrigerant (such as R-11 or another suitable medium) through line 21 to a condenser 22. In the condenser the water from the cooling tower passes from line 23 into the condenser, and is returned over line 24 to the cooling tower, or to the other head rejection means when difficult systems are used. The refrigerant at the discharge side of condenser 22 is passed over line 25, through a fixed orifice 26, and line 27 to the refrigerant inlet connection of the evaporator. The refrigerant passes through the evaporator and out the duct 30, which includes a plurality of inlet guide vanes 31 positioned as shown. In this description the inlet guide vanes are termed PRV, or pre-rotation vanes, and the position of the PRV is regulated by a small motor 32 which receives a control signal over a plurality of conductors, here represented as a single line 33. Those skilled in the art will readily appreciate that a plurality of conductors are represented by the single lines of FIG. 1. The higher temperature water from the building (or other cooling load) is returned over line 34, cooled in the evaporator 28, and the chilled water is returned to the building over line 35.
An induction motor 36 is coupled over shaft 39 to the centrifugal compressor 20, and this motor 36 is itself driven from an inverter 37. The inverter receives a d-c input voltage over line 38, thus determining the amplitude of the inverter output voltage. A voltage control circuit 40 is provided between a voltage supply line 41 and line 38 which passes the voltage to the inverter. This can be a conventional circuit, such as a phase-controlled rectifier circuit, which receives an input a-c voltage on line 41 and provides a d-c voltage on line 38 which is regulated in accordance with the signal received over line 42. If no regulation is necessary, a d-c voltage can be supplied over line 38 to the inverter from batteries, a transformer-rectifier, or any suitable source. The frequency of the inverter output voltage is regulated by the periodicity of the timing signals, or gating signals, supplied over line 43 from a logic circuit 44. This is a well-known circuit which receives a regulating signal on line 45 and utilizes this regulating signal to govern the frequency of the pulses supplied on line 43. One well-recognized arrangement receives a d-c voltage as a control signal on line 45, and a voltage-controlled oscillator in the logic circuit 44 provides pulses at a frequency determined by the amplitude of the signal on line 45. The logic circuit generally includes a ring-counter type circuit to distribute the pulses to as many thyristors or other switches as are used in the inverter circuit.
In accordance with the present invention, the control system 50 is utilized to regulate not only the speed of induction motor 36 but also the physical position of the pre-rotation vanes 31, by a speed control signal supplied over line 51 and a vane position (drive open or drive closed) signal supplied over line 33. The circuit arrangement of the invention insures that surge is avoided, and that the compressor is regulated in the most energy-efficient manner. In this embodiment the speed control signal is a d-c voltage supplied from an integrating circuit 52, and the vane control signal can be either an "open vanes" signal on line 53 or a "close vanes" signal on line 54, or no signal ("hold vanes"). These output control signals are derived from different input signals, including a first signal on line 55 which is provided by a thermistor or other temperature sensing unit 56 positioned to contact the refrigerant in the condenser discharge line as shown. A second signal is provided on line 57, obtained from a second sensing means or thermistor 58 which is exposed to the saturated refrigerant vapor leaving the evaporator. The first and second signals are combined in a summation means 59, which can be a differential amplifier circuit, to provide a resultant signal on line 60 which connotes the head of the compressor. The circuit means in the control system which utilize this signal, and the other input signals, will be described hereinafter in connection with FIGS. 6A-6C. For the present it is important to emphasize that the provision of the compressor head information from this simple temperature difference determination is an important aspect of the present invention. Without appreciating that the compressor head is a virtually linear function of this temperature difference, more expensive pressure transducers would have to be positioned in or adjacent the compressor itself to provide some signal related to the compressor head. Accordingly the realization that the compressor head can be inferred in this manner is an important part of the inventive contribution.
A potentiometer 61 is shown with its movable arm or wiper mechanically coupled to the PRV, or to the output shaft of motor 32 which drives the PRV. Thus the electrical signal on line 62 indicates the physical position (fully open 3/4 open, and so forth) of the inlet guide vanes in a continuous manner. Subsequently the circuitry will be described which combines this inlet guide vane position signal with the compressor-head-indicating signal to assist in regulating the compressor operation.
A third temperature sensing means, which can be another thermistor 63, is positioned to sense the temperature of the chilled water discharged from the evaporator 28. Thermistor 63 thus provides a third signal, which is applied over line 64 to another differential amplifier stage 65, which also receives a temperature set point signal from a potentiometer 66 or another suitable unit, such as a thermostat in the building space. Thus the output signal on line 67 represents the difference, if any, between the condition called for (denoted by the signal derived from component 66) and the instantaneous load condition (represented by the signal on line 64).
An unload control stage 68 is shown coupled to the movable arm of the potentiometer 66. For the purposes of this invention, stage 68 represents any means for limiting the consumption of electrical energy by changing the temperature set point, or effecting a different circuit adjustment, to change the load on the compressor and reduce the rate of energy consumption. Those skilled in the art will appreciate that this is similar to physically changing the thermostat setting, but in large installations this can be done automatically by a control system which monitors the rate of power consumption in successive time periods (such as half-hour intervals), and prevents the equipment from consuming more than a pre-set amount of power in each given time period.
Of the additional signal paths shown in FIG. 1, line 70 represents means for supplying a shut-down signal to the logic circuit 44 when an overload condition is sensed by the control system. To determine this, and other operating signals, a signal related to the amplitude of the current flowing through the windings of motor 36 is passed over line 71 to the control system, and another signal related to the motor speed is passed over line 72 to the control system. The motor current signal is derived from a current transformer in a well-known manner, and is not illustrated herein. The motor speed signal can be derived from a conventional tachometer (not shown), to provide a d-c voltage signal on line 72 which denotes the motor speed. It is not requisite to have an external set of conductors, as represented by line 72, to return a signal related to the motor speed. Instead the control system can use an internal line, tied to the output of stage 52 which provides the motor speed control regulating signal, and use a portion of this d-c speed signal to signify motor speed. With this general perspective of the complete refrigeration arrangement and the control system, a more detailed explanation will now be set out.
FIG. 2 is a graphical illustration of operating characteristics of a conventional compressor, taken from test block data. The compressor head is shown plotted against flow (or capacity), characteristics that will be described in more detail in connection with FIG. 3. The three surfaces depicted on the graph of FIG. 2 represent regions of system operation at a constant Mach number or compressor speed. For example, the uppermost surface depicts the possible variations in head and the capacity while operating at a Mach number of 1.5. If the operating parameters change and go beyond the longer of the upper boundary lines for the 1.5 surface, the surge region is entered, indicating the system will be unstable and the compressor will surge. The upper right line termination of this 1.5 surface represents operation with wide open vanes, and the three dash-dot lines are used to indicate the regions of operating at 3/4 open vanes, 1/2 open vanes and 1/4 open vanes. These regions are depicted as discrete lines but the system can be continuously adjusted over the entire vane-opening range, affording operation at any vane opening. For operating at a lower speed or Mach number of 1.4, the system "drops down" to the intermediate surface depicted in FIG. 2. Similarly, with a further reduction of operation to a 1.3 Mach number, the system drops down to the lowest of the three surfaces illustrated. It is also understood that in a system in which the compressor speed is continually adjustable, the Mach number changes are not made in large increments as shown, but the adjustment is continuous in the "space" between the surfaces depicted in FIG. 2 as the compressor speed is reduced. With this perspective of the compressor head-flow for regions of constant speed, a description of the compressor characteristics in another format will now be set out.
FIG. 3 is a graph illustrating the "minimum Mach number" Mo along the left ordinate, the extent of the PRV opening along the abcissa, and the compressor capacity θ, specified at selected points, all related to the compressor head Ω which is depicted by the series of curves shown on the graph. The "minimum Mach number" Mo can be considered to represent the motor speed. More accurately, it is the ratio of the impeller tip speed to the suction stagnation acoustic velocity (this velocity is hereinafter termed "A"). Because the induction motor is coupled to the compressor, the motor speed can be considered directly related to the impeller tip speed. For this analysis it is assumed that A, for a given refrigerant, does not change significantly over the typical operating range of the evaporator, and hence Mo can be considered a function of the motor speed alone. The PRV opening is represented in increments from fully closed to the wide open vane (WOV) condition. The capacity, depicted as θ, is technically the ratio of the suction (in cfm) times 2.4, and this term is divided by the product of A times the square of the impeller diameter. The compressor head Ω, represented by the curves in FIG. 3, is technically the measurement of the head (in feet) times the constant 32.2, and this product is divided by A2. Because A is considered not to change significantly, as noted above, it simplifies the consideration of the capacity θ and the compressor head value Ω.
Each of the different curves in FIG. 3 represents a constant head value Ω, and the minimum speed and PRV necessary to accommodate a given capacity without entering a surge region. For example the curve in the upper right portion with a head value of 1.2 indicates the motor speed and PRV opening changes which must be made to reduce the capacity at this head value. The arrow 75 shows the direction of decreasing capacity, and if only the motor speed (and thus the compressor speed) is reduced, the capacity is reduced as shown by the decreasing value of θ along the right side of the graph. However if the speed is reduced to the point referenced a, and it is still desired to further reduce the capacity without decreasing the compressor head below 1.2, at this point the motor speed must be maintained constant and the PRV gradually started to close, thus reducing capacity as indicated to the point b, where the value of θ is 0.058 and the vanes are approximately 3/4 open. The system will surge if, at point b, the speed more further reduced. It is important to note that for a further capacity reduction at the same head, the vane closure continues but the motor speed must now be increased, up to the point marked c.
In a similar manner, if the head value is 1.0, the vanes can be maintained wide open while the speed is decreased down to the value where θ equals 0.0385, at reference point d. From this point the speed is maintained constant and the vanes are gradually closed down, until they are about 3/4 open as shown at the point e. Hereafter the motor speed is again gradually increased while the vane closure is continued, to the point marked f. The points a-f are also shown on FIG. 2. Thus it is apparent that a complex control function is required to coordinate regulation of both the compressor speed (by regulating motor speed) and the opening of the PRV. The load line for a given system, when drawn on FIG. 3, would cut across the different head curves. Thus it is necessary to consider the change in head, as well as the present position of the PRV and the instantaneous motor speed, whenever a change is made in the system, to be certain that surge is avoided and the most efficient operation is achieved.
The control path for combining motor speed control and PRV opening control, found effective in achieving such regulation without going into surge, is depicted by the curve 80 in FIG. 4. The constant-head Ω curves are shown as background for the ideal control path 80. Suppose that the system is originally operating at full capacity with wide open vanes; this is represented at the point designated g. When it is desired to decrease the load, the capacity is reduced by reducing the motor speed, following the curve which passes through point h and eventually straight down to point j, at which time the control algorithm must be modified to include adjustment of the PRV position to maintain the optimum control path. The vanes are then gradually closed to about an 80% open position, while the motor speed is increased from the level indicated at j to that represented at the point k. From this point the vane closure is continued, but the motor speed is again reduced, until the control path 80 reaches the nadir at point m. At this part of the curve the vanes are about 35% open, and as the vane closure is continued, the speed is then increased up to the point n.
When it is desired to increase the load, considering the system is now operating under conditions represented at the point n, the PRV opening is gradually increased while the motor speed is decreased, until the point m is reached. Thereafter, as the vane opening continues, the motor speed is increased up to the point k. In accordance with an important aspect of this invention, the motor speed increase is continued, as the vanes are further opened, along the segment kh of the control curve; the other two legs, kj and jh, are not followed in restoring load. Instead the control path is directly from k to h, and then up to g after the vanes are fully opened.
Because it has been determined that this path avoids surge and achieves a very high operating efficiency, it is important that the control system "know" not only the amount of change required, but the direction in which the change is being effected. This requires both combinational logic and stored information regarding compressor performance in the control system, as will be described, to achieve the optimum control path 80 depicted in FIG. 4.
FIG. 5 is an illustrative diagram setting out general signal flows of the more detailed circuits depicted in FIGS. 6A, 6B and 6C. In general the chilled water outlet signal from thermistor 63 (FIG. 5), and the temperature set point signal, derived either from the potentiometer 66 or from any other means for establishing the desired temperature control level, are combined to produce a temperature error signal on line 67. A "dead-band" network 81 is provided to produce separate output signals on line 82 (which represents a plurality of conductors), to avoid giving switching commands to the PRV control logic circuit 96, and to the inverter speed logic circuit 83 when operating in the PRV control region, until the temperature error signal has exceeded the amount determined by the dead band. The output of the logic arrangement 83 is passed through integrating stage 52 to provide on line 51 the motor speed control signal, to regulate the inverter operating frequency and hence the motor and compressor speeds.
The vane position information of the PRV is taken from potentiometer 61 and, over line 84, a portion of this signal is applied to the inverter speed logic circuit 83. Another part of the PRV position signal is passed over line 85 to a duty cycle control circuit 86. In addition the PRV position signal is passed through a network 87 and combined with the minimum Mach number Mo signal on line 88. As described previously, this minimum Mach number for wide open vanes is derived from the condensing temperature as sensed by thermistor 56, and the evaporating temperature as sensed by the thermistor 58. These two signals are combined to provide the minimum Mach number Mo signal (for wide open vanes) on line 89. When this signal is passed over line 88 and combined with the output of network 87, it provides a composite signal on line 90 which is then combined with the actual motor speed signal received over line 72 to produce an error signal on line 91. This error signal is the error in speed set point when the system is controlling the PRV position, in addition to regulating the motor speed. The motor speed signal is also compared with the Mo signal on line 89 to produce on line 92 a logical signal indicating whether the actual motor speed is above or below Mo. This signal is then applied to the PRV control logic circuit 96 and, over line 99, to the inverter speed logic arrangement 83.
The duty cycle control circuit receives both the PRV position control signal over line 85 and, over line 93, another signal from an overload circuit 94. The output of circuit 86 is passed over line 95 to the PRV control logic circuit 96, which determines whether the vane position should be changed, the direction in which the vanes should be moved, and the amount of movement which should occur. The overload circuit 94 receives a signal over line 71 proportional to motor current and, in addition to providing a signal on line 93 to the duty cycle control circuit 96, provides another signal over line 97 to the PRV control logic circuit 96, and another signal over line 98 to the inverter speed logic control circuit 83. With this general perspective of the system, those skilled in the art will more readily correlate the showing in FIGS. 6A-6C with the entire apparatus arrangement depicted in FIG. 1.
In the showing of FIGS. 6A-6C, the chilled water outlet water temperature was derived from thermistor 63 and passed over line 64 and one of the 24K resistors to one input terminal of the differential amplifier 65. The signal from the set point potentiometer 66 is passed over the other 24K resistor to the other input connection of stage 65, providing the temperature error signal on the output line 67. To assist those skilled in the art the IC component identifications are given hereinafter, and the operating voltages of the different stages are shown in a circle. The+sign in a circle indicates the B+ voltage of 12 volts is applied to that point. The chilled water temperature and set point signals are also combined in another comparator stage 101, to provide a signal on line 102 to the inverter logic when a low-water temperature condition is sensed. The application of this signal, and other overload signals, are not shown in the logic circuit, but those skilled in the art will readily understand the application of this signal to shut down the inverter operation when the chilled water temperature is too low.
The stages 103 and 104 are connected in a lead-lag compensation circuit for the system. This network provides a phase lead at 0.007 hertz and a phase lag at 0.02 hertz. Thus the error signal on line 67 passes over line 69 to this network, so that the output signal of the network on line 105 is a compensated temperature signal for application to the inverter speed logic arrangement.
The signal on line 67 is passed through another comparator circuit 106 to provide on line 107 a logic signal, which is a logical 1 (or high voltage) when the chilled water outlet temperature is greater than the set point temperature, and is a logical zero (low voltage) when the chilled water temperature is less than the set point temperature. This is applied to one input connection of the NOR gate 108 as shown. Stages 110 and 111 are connected to provide logic signals on lines 112, 113 when the difference between the set point temperature and the chilled water temperature exceeds the amount of the dead band, or the dead zone. In the illustrated embodiment, the dead zone was set to include a temperature difference of �0.15� F., electrically represented by the difference between 5.12 volts and 5.86 volts applied to the two stages 111 and 110. A reference or center-band voltage of 5.5 volts is utilized as the reference. NOR stage 114 and an inverter stage 115 are connected as shown to provide a logic signal for use in the inverter speed logic control circuit. These stages, and the additional stages 116, 117, 118, 120 and 121 will be identified at the end of this description to enable those skilled in the art to use the invention with a minimum of experimentation. In addition another inverter 122 and the gates 123, 124 and 125 which regulate the application of signals to the integrating stage 52, will also be identified.
The signal from the PRV position potentiometer 61 is derived and supplied on line 62 as shown. A portion of the signal is supplied over line 84 to one connection of a comparator stage 130 which also receives a d-c reference signal at its other input connection. The wiper of potentiometer 61 is at the zero resistance (top) position in the wide open vane condition. This setting, and the other circuit components and voltages shown in the drawing, cooperate to produce a logical one signal on conductor 131 at the output side of stage 130, when the inlet guide vanes are in the wide open position. The signal becomes a logical zero when the vane opening is reduced from the wide open vane condition. The signal is applied to one input connection of the NAND gate 120, and is also inverted in the inverter stage 132. The inverted signal is passed over line 133 to the NAND gate 117 and to the NAND gate 134, the output of which provides one input to the NAND gate 135 in the PRV control logic circuit 96.
The vane position signal on line 62 is also supplied to the negative input connection of each of the comparator stages 136-140. The outputs of these comparators are respectively coupled to the gate circuits 141-145, as shown. These outputs from the gates are summed in stage 146 to provide a signal indicating the speed deviation from the minimum Mach number based on the actual vane position.
The refrigerant condensing temperature sensed by thermistor 56 provides a signal on line 55, and the refrigerant evaporating temperature sensed by thermistor 58 provides another signal on line 57. These two signals are combined in differential amplifier 59 to provide on lines 88 and 89 a signal related to the minimum Mach number Mo for wide open vanes. At this point in the circuit the signal is related only to the compressor head, and does not include any factor related to the vane position. A portion of the evaporator signal on line 57 is passed to another comparator 148, to provide on line 150 a shut-down signal for the inverter logic when the evaporator temperature drops below a pre-set value, which value is established by the reference voltage applied to the other input connection of this stage.
The Mo signal on line 88 is combined with the speed change signal at point 90, and applied to the negative input connection of op amp 151. Thus this connection receives a composite input signal which is a function both of the speed change signal and the minimum Mach number Mo. The other input connection of stage 151 receives an actual motor speed indicating signal over line 72, as described previously. Thus the output signal from stage 151 which is provided on line 91 to the inverter speed logic arrangement represents the error in the speed set point signal when the refrigeration system is operating in the PRV control region, where both the motor speed and the vane position must be regulated to follow the optimum control path 80 depicted in FIG. 3.
In FIG. 6B, the speed signal on line 91 is also applied to the+input connection of another comparator 153, which receives a reference voltage at its other input connection. Thus the output from stage 153 is a logic signal, passed over line 154 to the NAND circuit 120, signifying whether the actual motor speed is above or below the desired motor speed for the given operating conditions. In brief this logic signal is used to allow temperature error information to modify the motor speed control command and obtain faster system response, when such modification does not pose the danger of sending the system into surge.
The duty cycle control circuit 86 operates to limit the time of contact closure in the drive-open and drive-closed portions of the PRV control, as a function of the instantaneous PRV position. This is an important aspect of the present invention, because, when the vanes are closed down to leave only a small opening, it prevents a "drive closed" signal from being applied at a rate faster than the system response rate. The duty cycle control circuit 86 can also be considered a drive control circuit, in that it determines the percentage of the time, in a given time interval, that a drive signal is actually applied to the PRV motor 32, or to any suitable capacity control means which is adjustable to vary the capacity of the compressor. Hence PRV motor 32 is a means for regulating the adjustable capacity control means, the PRV themselves.
The problem posed by previous PRV control systems can be better understood in connection with FIG. 7. The several curves there shown illustrate variations in compressor capacity as a function of the PRV opening, for different constant values of head (Ω). For example the curve 300 indicates the capacity-vane-opening relationship for a compressor head value of 1.2. The succeeding curves 301, 302, 303 and 304 depict decreased values of compressor head, down to an Ω of 0.8 for curve 304. As the compressor head drops to 1.0 and values below that level, the slope of the curve portions to the right of a PRV opening of about 1/2 become increasingly smaller. However for low values of PRV opening, irrespective of the head value, the slopes of the curves are very great. Thus it is manifest that a very slight physical displacement of the inlet guide vanes, when the vanes are closed or almost closed, effects a very large change in the system capacity. It would be desirable if the curve shown in FIG. 7 where more linear, and it is toward a linearization of the system operation that the duty cycle control circuit 86 is directed.
The duty cycle control circuit or drive control circuit 86 (FIG. 6B) basically comprises an integrator stage 156, a NOR gate 157, and a comparator stage 160. This drive control circuit receives two different input signals. A first input of the drive control circuit can be considered conductor 200, which receives a timing signal from the oscillator 155. This timing signal, at 0.033 hertz in the illustrated embodiment, is applied over the 1.3M resistor to the upper input terminal of integrator stage 156, and is also applied to the upper input terminal of NOR gate 157. This signal is represented generally by the waveform 201 in FIG. 8A. NOR gate 157 will provide a logical 1 output signal when both inputs are low, or 0. When the oscillator signal represented by the waveform 201 goes low, the 5.5 volts reference voltage on the other input terminal of integrator 156 allows this stage to begin charging at time to, and produces an output voltage such as 202 (FIG. 8B) over line 161 to the upper input terminal of comparator 160. This comparator also receives a position signal over line 85; this position signal varies as a function of the setting of the adjustable capacity control means, which in this embodiment is the PRV of the compressor. When the PRV is virtually fully closed, the d-c voltage level on line 85 is approximately 2 volts, represented by the line 203 in FIG. 8B. When the increasing signal from integrator 156 over line 161 intersects the 2 volt line at point A, comparator 160 switches at time t1, represented by waveform 204 (FIG. 8C). Thus for the time between to and t1, the signal from comparator 160 was low, and the signal depicted by curve 201 (FIG. 8A) from the integrator 156 was also low. Hence the output of NOR gate 157 was high at this time, as shown by the pulse near the beginning of curve 205 in FIG. 8D. So long as the comparator output remains high, shown by curve 204, there is no further output from the NOR gate 157. The signal 204 goes low again when the decreasing slope of curve 202 intersects the 2 volt line, at time t5. However at this time the oscillator output is high, and hence there is no further output from NOR gate 157 until the increasing-slope portion of the integrator curve 202 again intersects the 2-volt line 203. Thus the drive signal to the PRV, or to the means for regulating the adjustable capacity control means, is clearly a function of the vane position, represented by the level of the signal on input line 85.
Supposing that the PRV are virtually wide open, a 10 volt signal is provided over line 85; this signal is represented by the line 206 in FIG. 8B. It is thus apparent the increasing-slope portion of curve 202 will intersect the 10 volt line at point B, or at time t3 shown in curve 207 of FIG. 8E. At this time the output of comparator 160 goes high, as shown on curve 207, preventing any output from NOR gate 157. However prior to that switching, between times to and t3 as shown on curve 208 in FIG. 8F, the output of NOR gate 157 was high becuase both inputs to this gate were low. This provides a much longer duration pulse in the curve 208 for driving the PRV or any other adjustable capacity means. In the illustrated embodiment, the circuit components provided a pulse of approximately 1 second on the waveform 205, and approximately 5 seconds in the waveform 208. Intermediate positions of the PRV provide corresponding intermediate pulse lengths. Of course other drive control circuits could be employed to provide a variation of some other signal characteristic, such as amplitude, to regulate the change in the adjustable capacity control means in accordance with the instantaneous position of the adjustable capacity control means.
The capacity control signal is passed from NOR gate 157 into the NAND gate 162, and also passed upwardly into the other NAND gate 135. The operation of the logic arrangement for driving the vanes open or closed is achieved with the additional stages 163-168, and 170, connected as shown.
For example, a logical zero signal from NOR gate 165 (FIG. 6C) provides no gate drive for the NPN-type transistor, energizing the light-emitting diode from B+ and the 1K resistor, and providing gate drive to the thyristor, which is energized and provides a close-vane signal on line 54. The terminal below the 0.27 microfarad capacitor, marked X, corresponding to the other similarly marked terminal in the open-vane circuit, represents a common electrical connection for the PRV motor. Of course, the system can be manually operated by displacing the mode selector switch 171 from the automatic position, in which it is illustrated, to either of the other three positions. When the movable contact is displaced to engage the "hold" contact, then the vane motor cannot be driven open or closed but remains in the present position. When displaced to contact the "open" contact, an energizing circuit is completed to gate on the thyristor and provide a signal on line 53 to open the vanes. Similarly when the switch is further displaced to engage the "close" contact, operation of the logic circuit provides the gate drive signal necessary to energize the thyristor and provide the close-vane signal on line 54.
The motor current level signal is received over conductor 71 and divided over the illustrated 3K potentiometer, with a portion of this signal being diverted over line 172 to the first current limit stage 174. When the level of the motor current reaches a previously determined value representing 100% of the current rating, stage 173 switches and provides an output signal which is passed both to the PRV logic control circuit and to the inverter speed logic control circuit as illustrated. In the inverter speed control portion, this means that the inverter motor cannot be driven any faster while this 100% current level is maintained, and the speed will in fact be reduced. In addition, the operation of the PRV logic control circuit under these conditions is such that the vanes cannot be driven open, but when a decrease-load signal is provided, the vanes can be driven closed to reduce the loading on the system. If the current level increases further, to a level indicating 103% of the rated current is flowing in the motor windings, stage 174 is switched to provide a signal to the PRV logic control circuit which begins to drive the vanes toward the closed position, to reduce the load. If the current increases further to the level of 106% of rated current, this signal is sensed over line 175 and stage 176 switches to provide on line 70 a signal which shuts down the inverter logic and thus correspondingly removes the motor energization.
FIG. 9 illustrates a pair of curves depicting the variation of compressor speed as a function of the opening of the PRV, for a fixed compressor head value. Curve 307 depicts a surge curve line developed from actual data, so that operation in the lower left portion of this curve would cause compressor surge. To avoid encountering surge, an actual functional 308 was derived, representing a mathmatical function to regulate operation of the control system of this invention. By regulating the speed of the electrical prime mover 36 and the extent of opening of the PRV to follow the functional 308, not only is surged avoided, but the system is operated in substantially the most energy efficient manner. That the control system can regulate operation along curve 308 is due in part to the effective derivation of the minimum Mach number Mo on line 89 (FIG. 5) from the condensing and evaporating temperatures. Thereafter this minimum Mach number, or head-indicating signal, is passed to the output side of network 87. The signal derived from PRV position potentiometer 61 is modified by the network 87 to produce a modified or functional signal for combination with the minimum Mach number signal on line 90. This combination of signals on line 90 produces a signal which is then combined with the actual motor speed signal on line 72 to produce a "speed boost" signal for the inverter speed control portion of the control system. The term "speed boost" refers to the speed correction desired for the induction motor driving the compressor, considering the minimum Mach number Mo, the functional signal at the output side of network 87, and the actual motor speed signal. The resultant speed boost signal provides an efficient corrective value for regulating the induction motor speed in an optimum manner.
The present invention provides effective control for refrigeration systems using compressors having adjustable inlet guide vanes, in which the compressor is driven by a variable speed electrical motor. The system and method of the invention were successfully tested, and proved that automatic adjustment of compressor speed and the inlet guide vane position could match the compressor head and flow requirements for a given evaporator load, while maintaining the chilled water at a constant temperature. The path of control, as shown in FIG. 4, tends to minimize system energy requirements while at the same time avoiding compressor surge. In addition the control system and the control method of this invention have shown a capability of maintaining the chilled water within 0.15� F. of its set point, throughout the entire feasible load range. In particular the maximum possible use of motor speed control is effected, before beginning to adjust the PRV position to vary the compressor load. This is the most energy-efficient method for operating an arrangement with adjustable inlet guide vanes, and has proved significantly more efficient than systems using a combination of PRV control and hot gas bypass to prevent surge. Th present arrangement has eliminated the need for a gear box, and allowed operation with smaller, more efficient, higher speed motors. In addition the compressor is quieter at part load operation, it is driven more slowly, at a vane angle more suited to noise reduction.
The invention is in part based on the appreciation of the compressor characteristics, and the derivation of the minimum Mach number Mo, which is limited by the head on the compressor. This use of the Mach number for wide open vanes is continually monitored in the control system, to match the load requirements to the capacity of the compressor at that time. It is very important that the maximum range of speed control be utilized, before switching to the region of PRV control as described in connection with FIG. 4. The derivation of the head information from the two temperatures is a significant aspect of the invention. This provides accurate control with minimum transducer cost, because thermistors can be used in place of the more expensive pressure sensors frequently used in such arrangements.
The system and method of the invention regulates the refrigeration system in both the "speed control" region and in the "PRV control" region. In the speed control region, the concept of control is simply to adjust compressor speed by regulating the frequency of the inverter output voltage either up or down, depending on whether system capacity needs to be increased or decreased. The error in chilled water temperature, with respect to the set point, is used to define needed system capacity changes. The technique is easily understood and, after defining the response, stability, and loop compensation requirements, can be readily implemented with low cost electronic circuitry. In the PRV control region, chilled water error changes require a more complicated set of control changes and continuous monitoring of system variables. Not only does the PRV position need to be adjusted, but in order to avoid surge, the compressor speed must be concomitantly regulated according to head measurements and a pre-stored function of PRV position (network 87). Superimposed on these two regions of control characteristic, and its attendant boundary definition problem, is the requirement that the path of control chosen for compressor speed and PRV position adjustment must be energy conservative.
In the method and system of the invention, the observation that the compressor head is a nearly linear function of the difference between the refrigerant condensing and evaporating temperatures was of prime importance. Furthermore, experimental data on the compressor used demonstrated that the minimum allowable Mach number, to avoid surge, was linearly related to compressor head. Thereafter it was discovered that compressor head, in combination with the PRV position, could be used to define surge locii of the compressor at part vanes as well as at wide open vanes, and thereby produce the desired system operating path shown in FIG. 4. Thus signals from relatively low cost transducers, indicating condensing and evaporating temperatures, compressor speed, and PRV position, together with the chilled water temperature, form the basis for the effective control system and method of this invention.
The method of system control can be readily understood in connection with FIG. 5. In the method, the compressor head signal is continually established as a function of the condensing refrigerant and evaporating refrigerant temperatures; this head signal appears on line 89. A functional signal, related to the instantaneous position of the inlet guide vanes, is derived at the output side of network 87. The head-indicating signal and the functional signal are then combined to produce an intermediate signal on line 90. A signal related to the actual motor speed is provided on line 72; this can come from the motor, or from line 51, or some other source. The actual motor speed signal and the intermediate signal are combined to provide a first signal, on line 91, for use in regulating the speed of the compressor drive motor. A temperature error signal, related to the difference in temperature between the cooling medium at the evaporator outlet and the desired temperature set point, is produced on line 67, and the temperature error signal is used as a second signal for regulating both the speed of the compressor drive motor and the position of the inlet guide vanes.
Another way of understanding the method of the invention is in connection with FIG. 4. As there shown, the system is considered to be initially operating at a first operating condition, referenced g. Then the compressor drive motor speed is reduced, while the inlet guide vanes are kept wide open, from the first operating condition (g) through a second operating condition (h) to a third operating condition (j). Then a gradual closing of the inlet guide vanes begins, and simultaneously the compressor drive motor speed is increased, to reach a fourth operating condition (k), Closure of the inlet guide vanes is continued while the drive motor speed is simultaneously reduced, to reach the fifth operating condition (m). Closure of the inlet guide vanes is continued, while simultaneously increasing the drive motor speed, until a sixth operating condition (n) is reached.
It is important to note that the control sequence to again restore capacity to the system is significantly different from that just described (g, h, j, k, m, n) if the most energy-efficient path is followed. First the inlet guide vanes are gradually opened while the compressor drive motor speed is decreased as the system moves from the sixth operating condition (n) to the fifth operating condition (m). Then the inlet guide vanes are further opened while simultaneously increasing the motor speed, while the system moves from the fifth operating condition (m). Then the inlet guide vanes are further opened while simultaneously increasing the motor speed, while the system moves from the fifth operating condition (m) to the fourth operating condition (k). The opening of the inlet guide vanes is increased, and simultaneously the compressor drive motor speed is increased, as the system moves from the fourth operating condition (k) directly to the second operating condition (h), without going through the third operating condition (j). The inlet guide vanes are fully open at the second operating condition (h). Lastly, the compressor drive motor speed is increased to increase the system capacity, until the first operating condition (g) is again reached. More succintly, the method of the invention regulates the position of the inlet guide vanes and the speed of the compressor drive motor substantially according to the functional variations illustrated in FIG. 4 and described above, to avoid surge while operating in an energy-efficient manner.
Those skilled in the art will appreciate that the control system of the invention is similarly applicable to regulate a heat pump arrangement, in which both the speed of the compressor and the amount of gas admitted to the compressor are varied to follow an optimum control path.
To assist those skilled in the art to implement the invention, below is a list of the integrated circuit (IC) types, and identification of other components not already specified on FIGS. 6A-6C.
______________________________________IC Type Stages (FIGS. 6A-6C)______________________________________MLM2902P 59, 140, 148, 149MLM2902P 136, 137, 138, 139MC14016BCP 141, 142, 143, 144MLM2902P 65, 101, 103, 104MLM2902P 106, 110, 111, 156MLM2902P 130, 146, 151, 153MC14016BCP 123, 124, 125, 145CA3160S 52MLM2902P 160, 173, 174, 176MC14572BCP 114, 115, 116, 117, 122, 132MC14023BCP 120, 135, 162MC14001BCP 108, 121, 165, 167MC14011BCP 134, 164, 166, 170MC14001BCP 118, 157, 163, 168MC14541BCP 155T2310A All TriacsNSL5057 All led's2N3415 All transistors1N914 All diodes______________________________________
With this explicit and detailed exposition of the inventive principles and a preferred embodiment of the control system, it is evident that such a system can be utilized both with existing equipment, by way of retrofit, and with newly installed systems.
In the appended claims the term "connected" means a d-c connection between two components with virtually zero d-c resistance between those components. The term "coupled" indicates there is a functional relationship between two components, with the possible interposition of other elements between the two components described as "coupled" or "intercoupled".
While only a particular embodiment of the invention has been described and claimed herein, it is apparent that various modifications and alterations of the invention may be made. It is therefore the intention in the appended claims to cover all such modifications and alterations as may fall within the true spirit and scope of the invention.
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|U.S. Classification
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|International Classification
|Cooperative Classification
|European Classification
|Feb 4, 1987
Owner name: YORK INTERNATIONAL CORPORATION, 631 SOUTH RICHLAN
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST. EFFECTIVE;ASSIGNOR:BORG-WARNER CORPORATION;REEL/FRAME:004676/0360
Effective date: 19860609
|May 2, 1989
Owner name: CANADIAN IMPERIAL BANK OF COMMERCE
Free format text: SECURITY INTEREST;ASSIGNOR:YORK INTERNATIONAL CORPORATION;REEL/FRAME:005156/0705
Effective date: 19881215
|Jan 31, 1992
Owner name: CANADIAN IMPERIAL BANK OF COMMERCE
Free format text: SECURITY INTEREST;ASSIGNOR:YORK OPERATING COMPANY, F/K/A YORK INTERNATIONAL CORPORATION A DE CORP.;REEL/FRAME:005994/0916
Effective date: 19911009
|Feb 4, 1992
Owner name: CANADIAN IMPERIAL BANK OF COMMERCE
Free format text: SECURITY INTEREST;ASSIGNOR:YORK INTERNATIONAL CORPORATION (F/K/A YORK OPERATING COMPANY);REEL/FRAME:006007/0123
Effective date: 19911231
|Jul 8, 1992
Owner name: CANADIAN IMPERIAL BANK OF COMMERCE
Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:YORK INTERNATIONAL CORPORATION, A DE CORP.;REEL/FRAME:006194/0182
Effective date: 19920630


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Worst of group as I have been warning.......
and revenue now at a run rate of 63% of peak (versus 90% for COCO)
limited cash losses are great, but we will see how fast and how long management can cut costs as secular decline for CECO revenue continues
Lousy industry - I agree
Bad company - I agree
But - plenty of cash and turnaround in process and
the most important parameter - ridiculous share price!
That's the way to make money
Sentiment: Strong Buy
I understand where you are coming from and as I have said in the past, I truly think this sector is beat up well beyond where it needs to be. However, the best way I have made money over the past 24 years is to study an industry first, and then drill down to individual participants. Not to sound like a broken record, but CECO may be in secular decline and COCO and ESI are dirt cheap and are probably not in secular decline, and APOL is very close to dirt cheap and is likely also not in secular decline. Further, CECO has a very high fixed cost based of approx. $438mm in its Cost of Services account (this is far higher than the others). In other words, it cannot cut below that level not matter how far revenue drops. I continue to recommend (as I have since $7 to $8 per share) avoiding CECO and focusing on the rest of the sector.
Best of luck all, and be sure to really study an industry and a company and not guess based simply on statistics.


text:
COLUMBIA -- Eric Norwood stresses that he's not best buds with Clemson running back C.J. Spiller, but the South Carolina linebacker did say he admires Spiller's game.
"I root for him when we're not playing against them," the Butkus Award semifinalist linebacker said. "I'm cool with Spiller. We're cool. I like to watch him play. I just don't want him to have a big game against us."
The Tigers senior will get his shot this week when his team visits Williams-Brice Stadium.
In three years against the Gamecocks, Spiller has rushed 42 times for 352 yards (8.4 yards a carry). Here's an odd Spiller stat: In each of the past two meetings, both Clemson victories, he's rushed 16 times for 88 yards. (It forced a journalist's double-take.)
He ran 10 times for 155 yards against USC as a freshman, in South Carolina's lone victory against him.
Norwood said that was the day the players first bumped heads.
"We talk a lot during the game," he said. "We talk trash."
Since then, they've bonded to some level. Norwood said they worked a camp together once.
What's Norwood think of Spiller's Heisman chances?
"I think if their record was a little better, he'd probably have it," Norwood said.
Reid on mend again
Former walk-on Zac Brindise got second-team snaps at practice Monday night.
"He actually threw the ball around pretty well," head coach Steve Spurrier said.
Typical reserve Reid McCollum missed practice because he has some sort of a virus. McCollum wasn't available for the Ole Miss game, back on Sept. 24, because he had the flu.
"Yeah, he's been sickly this year," Spurrier said of McCollum, the Summerville native. "He's been sick more so than some of the other guys. We need to get him tested."
Line talk
Junior right tackle Hutch Eckerson (shoulder) was in a non-contact jersey and was limited at practice Monday.
If he can't go, Quintin Richardson would get the start there. Richardson, a redshirt sophomore, started the first four games of the season before being overtaken by Eckerson.
Also related to the line, position coach Eric Wolford said last week (and again Monday) that he expects Pierre Andrews, Seaver Brown and Kevin Young -- all fourth-year juniors -- to be honored Saturday with senior day festivities.
The Gamecocks have several incoming line prospects that will need scholarships.
Getting healthy
Norwood said he could see a difference in the energy level at practice Monday after the Gamecocks finally had their open date.
"A lot of guys, you could see they had their legs back under them," he said.
Spurrier said he'd still like to see that bye week come earlier in the fall, as it will next season.
Cliff Matthews was probably a Gamecock that needed the open week. He dislocated his shoulder Oct. 31 at Tennessee, returning two weeks ago against Florida in a limited role.
"He should be very close to 100 percent," Spurrier said.


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Boomers Marketplace & Bluebonnet Bakery
11600 N Penn Ave
Oklahoma City, OK 73120
Boomers Marketplace & Bluebonnet Bakery in Oklahoma City is a multi-vendor market boasting one-of-a-kind antique finds ... read more...
Oklahoma Contemporary Arts Center
3000 General Pershing Blvd
Oklahoma City, OK 73107
Oklahoma Contemporary Arts Center, formerly known as City Arts Center, provides interactive arts experiences through ... read more...
3022 Paseo
Oklahoma City, OK 73103
Star Dance Swan features classes, community workshops, and performances in expression through modern and creative dance ... read more...
Fortune Favors the Brave Mural
800-225-5652, 405-297-8912
4416 N Western Ave
Oklahoma City, OK 73118
Western Avenue in Oklahoma City commissioned local artists to paint murals across the district. This 2014 "Fortune ... read more...
3630 NW 39th St
Oklahoma City, OK 73112
Stop in to the Porthole Club in Oklahoma City for a night of fun and ice cold beer. You'll make some new friends and ... read more...
2200 NW 39th Expy
Oklahoma City, OK 73112
If you're looking for a wild time, look no further than The Copa in Oklahoma City. This LGBT-friendly nightclub offers ... read more...
4041 SW 149th St
Oklahoma City, OK 73170
JR's Pub & Grill in Oklahoma City, just outside of Newcastle, stays open late seven days a week, making it a great ... read more...
5826 NW 51st St
Oklahoma City, OK 73122
Take a hot air balloon ride with OKC Balloons Aloft and see the greater Oklahoma City area from a new perspective. ... read more...
4745 Council Heights Rd
Oklahoma City, OK 73179
Since 2009, COOP Ale Works in Oklahoma City has been brewing craft beers for all to enjoy. These homegrown brews have ... read more...
Oklahoma River & River Regatta Park
701 S Lincoln Blvd
Oklahoma City, OK 73109
Along the edge of downtown Oklahoma City runs the Oklahoma River, a 7-mile-long waterway that has reinvented outdoor ... read more...
Oklahoma City Zoo & Botanical Garden
2000 Remington Place
Oklahoma City, OK 73111
Adventure awaits you at the Oklahoma City Zoo & Botanical Garden. Featuring 1,800 animals located on 120 ... read more...
520 N Meridian Ave
Oklahoma City, OK 73107
Since serving their first beer in 2009, the Mustang Brewing Company, located on Meridian in Oklahoma City, has garnered ... read more...
5800 N Classen Blvd
Oklahoma City, OK 73118
Classen Curve is an upscale outdoor shopping mall in Oklahoma City. Tucked just off Classen Boulevard, the appropriately ... read more...
4801 S Eastern Ave
Oklahoma City, OK 73129
OKC Limits off Eastern Avenue in Oklahoma City is a great place for cold drinks and live entertainment with delicious ... read more...
307 NE 2nd St
Oklahoma City, OK 73104
Located in one of downtown Oklahoma City's historic neighborhoods, Deep Deuce Grill offers a variety of tasty menu ... read more...
3938 W Reno
Oklahoma City, OK 73107
Henry Hudson's Pub in Oklahoma City offers a place to relax, hang out with friends, have a drink and grab a bite to ... read more...
1112 NW 23rd St
Oklahoma City, OK 73106
The Gold Dome Building, famous for its unique architecture, is a geodesic dome and major landmark along historic Route ... read more...
12100 A-1 N May Ave
Oklahoma City, OK 73120
If you're looking for a unique food or ingredient, the Gourmet Gallery in Oklahoma City is sure to have it. They have a ... read more...
2219 Exchange Ave
Oklahoma City, OK 73108
Cowhide and exotic skin boots and accessories. Located in historic Stockyards City district. ... read more...
1 E California Ave
Oklahoma City, OK 73104
Located in downtown Oklahoma City Mojo's Blues Club, also known as the Biting Sow, is the only blues club in ... read more...
6728 N Olie
Oklahoma City, OK 73116
Henry Hudson's Pub in Oklahoma City offers a place to relax, hang out with friends, have a drink and grab a bite to ... read more...
5501 SE 119th St
Oklahoma City, OK 73165
Kitchen Lake Park in south Oklahoma City is a charming place to spend an afternoon outdoors. Part of the city's ... read more...
4141 N Western Ave
Oklahoma City, OK 73118
Explore the realm of plant decor possibilities with a trip to The Garden Gnome Bonsai in Oklahoma City. Tour ... read more...
4309 N Western Ave
Oklahoma City, OK 73118
If pimento cheeseburgers served on a pretzel bun or fried chicken and waffles sound good to you, head over to The Drum ... read more...
1 E Sheridan
Oklahoma City, OK 73104
Part art gallery and part boutique, Exhibit C is a Bricktown attraction that showcases the unique work of local artists ... read more...
2304 N Western Ave
Oklahoma City, OK 73106
Cookie's is a beloved dive bar in Oklahoma City known as a great place for karaoke. It is a quaint building with ... read more...
Bricktown Entertainment District
Oklahoma City, OK 73102
Get around Oklahoma City's Bricktown Entertainment District in style and hail a ride from Thunder Up Pedicabs. ... read more...
Architectural Antiques & Dead Peoples' Stuff
1900 Linwood Blvd
Oklahoma City, OK 73106
Stained glass windows and apothecary cabinets are just a few of the items you'll find at the quirky Oklahoma City ... read more...
424 Colcord Dr
Oklahoma City, OK 73102
Canterbury Voices holds three concerts each season, beginning in the fall and ending in the spring. ... read more...
800-229-2118, 405-751-7243
3031 W Memorial Rd
Oklahoma City, OK 73134
The Fox and Hound Bar & Grill, located in Oklahoma City, is a fun place to grab a bite to eat or enjoy a drink with ... read more...
National Cowboy & Western Heritage Museum
1700 NE 63rd St
Oklahoma City, OK 73111
Formerly known as the National Cowboy Hall of Fame, the National Cowboy & Western Heritage Museum in Oklahoma ... read more...
4409 N Meridian Ave
Oklahoma City, OK 73112
For one of Oklahoma City's largest selections of antique silver, crystal and glassware, head to Antique House. The shop ... read more...
11411 N Kelley Ave
Oklahoma City, OK 73131
Silverhorn Golf Club in Oklahoma City is an 18 hole public course with pro shop, snack bar, driving range and banquet ... read more...
1705 A NW 16th St
Oklahoma City, OK 73106
Collected Thread features handmade and hand-altered clothing and accessories in Oklahoma City. Located in the ... read more...
Lazy J Ranch and Rodeo Company & Carriage Rides
Reno Ave & Mickey Mantle Dr
Oklahoma City, OK 73104
Enjoy an enchanting evening in Oklahoma City's historic Bricktown Entertainment District with a horse drawn carriage ... read more...
7312 N Western
Oklahoma City, OK 73116
Bin 73 Wine Bar in Oklahoma City is a prime destination for those who love wine. This unique bar and restaurant ... read more...
Oklahoma Backroads Motorcycle Tours
Oklahoma City, OK 73110
Hit the open road with tour guide Bill Long and explore unique attractions, roads, areas, historic sites, diners and ... read more...
2300 N Lincoln Blvd
Oklahoma City, OK 73105
Located on more than 100 acres in NE Oklahoma City, the Oklahoma State Capitol features ... read more...
1305 S Agnew
Oklahoma City, OK 73108
What began in 1910 as the Oklahoma National Stockyards Company, a public livestock market, has since become Historic ... read more...
323 E Sheridan Ave
Oklahoma City, OK 73104
Candy Nightclub is one of the hottest dancing spots in Oklahoma City. Located in the heart of the Bricktown ... read more...
Email: firstname.lastname@example.com


text:
Originally Posted by sremick
Perfectly spoken...
It really first comes down to the type of games you like. BAsed on what you have said it seems like you could be happy in pretty much any aspect of gaming.
Now with Nintendo you will get more variety overall of game types and very dedicated and long list of 1st party games like Galaxy,SSBB,Mario Kart,Strikers,Mario Party ect.ect. But Nintendo hasn't been the best supported 3rd party game wise for some time now, and it's more of a gamble than a guarantee that the 3rd party will wise up enough to show support for the dominating console "sales wise".
Don't get me wrong they are getting some big titles like GH3,Rockband,Starwars, ect. But the big "hardcore titles" like GTA,COD,FF type games will not shine on the Wii unless they design it specific for the Wii as opposed to a cheep port, and so far this attutuide twards the Wii seems to be in the minority for 3rd party.
With 360 you get THE BEST online support with a few very good 1st party games, Beyond that you will also get almost a complete list of the top 3rd party titles aswell to join it. There has been hardware issues but as its been pointed out they are dealing with them and it seems to be very well so far.
If the games can't sway you one way or another ask yourself what type of gaming you do more.
Is most of your gaming by yourself or playing friends online? " If so go 360"
Or is most of your gaming shared with the company of friends in your home and the occasional online? "If so you want the Wii"
Touchy subject really only you can decide in the end based on your own taste.
Originally Posted by sremick
Perfectly spoken...
Exactly.Originally Posted by T3kNi9e
You should really just do your own research, and find out which current/announced games you'll enjoy playing the most.
I have both, all three consoles actually. I find I play my 360 the most, followed by the Wii, then the PS3 (mostly use it for Blu-rays). The 360 has the best online play by a mile. But with family and friends over, the Wii is the most fun! It all depends on what kinds of games you're into. I'm in love with Halo so I had to have the 360 but it sounds like you're a big SSB fan so maybe the Wii is for you.
I would say buy a wii first because it's cheaper, reliable, dependable, and different. You can buy a 360 in a few months when they come out with a better version with blu-ray because they need to compete with Sony. If you buy a 360 first like right now, a newer better version will be out soon and you just wasted your loot. You won't be dissapointed with the wii since you like Brawl. Plus there's Mario Galaxy where you can defy gravity, then grapple and shoot with Metroid, blow up zombies heads into pieces w/ RE4, fly and drift w/ Excite Truck, box, bowl, and slap some tennis balls w/ your granny or girlfriend if you have one w/ Wii Sports, Mario Strikers Charged even if you don't like soccer, slice your foes with the wiimote in Zelda, jump from 2d to 3d in Paper Mario, old skool VC Nintendo Games, become a genius w/ Big Brain and Zack n Wiki, shoot light gun arcade style w/ RE:UC, House of the Dead, Ghost Squad, the list goes on....
Last edited by bruceleroy; 03-12-2008 at 07:29 AM.
not really.Originally Posted by ladieraven
people have been doing it for years LOL.Originally Posted by iceblade
Everything in this signature except for this text was made by Wiired, he is my creator and almighty.
What is your brilliant input on this subject Sovieto. You keep making remarks about what everyone else has to say, without any of your own input. Your doing a good job of helping this kid decide which console to choose.
If u want a system for great online play... Just go with the 360.... period... I am not gonna be fanboyish.... Wii's online has yet to prove itself a good online system
VideoGameCountdown (Youtube)
Spoiler Alert!Originally Posted by sorabrawlOriginally Posted by Arsid
Whats the deal with pc gamers thinking that aiming is terrible on controllers, sure its easier with the mouse but after a few days it becomes natural to aim with the controller.
Anyway, back on topic. At first I bought a wii and had fun with it for about half a year, started to get bored and I slowly used it less and less. I then bought a 360 and sold my wii a few months later. I'd say get a 360 for some epic multiplayer & games, but if you're unsure do some research and find games that you like on whatever console.
The very existence of flamethrowers proves that sometime, somewhere, someone said to themselves, You know, I want to set those people over there on fire, but Im just not close enough to get the job done.
- George Carlin
Remember games dont have to be packed with adult content to be hardcore. And DS owns PSP anyday btw.Originally Posted by highroller


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G3 Rutschblock Cord
5.75 m / 18 ft 10 in
Where to Buy
sponsored links
Manufacturer's Description
Visit G3's G3 Rutschblock Cord page.
Retailers' Descriptions
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Hotel Ruta Jacobea
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Pilgar Schwesters
... pastries. It wasn't an especially sustaining breakfast, but a reminder that some of us had choices due to our finances, and humbling to imagine living off of handouts, leftovers. The four others were from France, Estonia, Japan, and the Czech Republic. Quite the international group...Following breakfast, we went to the cathedral in hopes of catching a Mass in English. When we arrived, Mass was just finishing up for All Souls' Day, and the recessional turned ...
38. Pedrouzo to Santiago de Compostela
... the top floor and the window looks out to the cathedral tower. Luckily it's the one without scaffolding. While I still have the patience, and strength, I leave my stuff and head to the Officio de Pelegrini to get my compostela. For another 2eu I can get another one that is personalised. And for another 2eu a tube to roll them up in. An investment to be sure. I've bumped into a number of people I've met along the way. Some leave tomorrow to walk to Finisterre. Others are on ...
St.James of the Field and Star
... are the remains of St. James.
There were many signs forbidding cameras with flash and although certain individuals ignored the request I decided that the new me would obey it. It is here for others to see and not just me.Its interior was as simplistic as the exterior although there was a sense of peace and welcome within.I saw the mighty Botafumeiro with its marvelous engineered pulleys and ropes and was quite excited by what was ...
Day 35
... accomplishment but remain cautious knowing the Camino can take away as fast as it can give: a fall from a bunk, a twisted ankle on an ancient Roman rock in the road, an infestation of bedbugs or a piece of bad chorizo. We have decided to forgo thoughts of attending noon mass on Friday in Santiago where it is said that the giant incense burner will swing from the ceiling (a special event only offered periodically but heralded by all ...
Sole to Soul
... sign Pulperia... There was a man outside preparing fresh octopus which is one of their specialties. We met eyes snd I thought, I'm taking a shower and rest and I am having my meal there... The owner once again saw that tired pilgrim look and escorted me directly to my room..what a scrapbook of ragged pilgrims they could put together.. Did my pilgrim routine and was fresh and ready for a hearty meal... Got to the restaurant and he had just served the ...


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Two Women's Prize for Fiction nominees plan Milwaukee visits
The Women's Prize for Fiction, the successor to the former Orange Prize for Fiction, has released its longlist of 20 nominees for the prize.
It includes a few of the most popular novels of the past year, notably Gillian Flynn's "Gone Girl" and Hilary Mantel's "Bring Up the Bodies," as well as a raft of other promising works from established (Zadie Smith, Barbara Kingsolver) and emerging writers (Elif Shafak, Bonnie Nadzam, Shani Boianjiu). »Read Full Blog Post
Florentine Opera plans Wagner's 'Flying Dutchman,' 'Wuthering Heights' next season
For the 2014-'15 season, the Florentine Opera Company will stage its first new Wagner production in a decade.
The Florentine also plans to record a concert performance of contemporary composer Carlisle Floyd's"Wuthering Heights" for a planned commercial recording. »Read Full Article
SoMo; Martina McBride; Manchester Orchestra; Carlene Carter; MercyMe; Nathaniel Rateliff; Saintseneca; Michaela Anne; Katie Herzig
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On Tap Today: The Milwaukee Admirals pay tribute to 'Major League'
The Milwaukee Admirals will pay tribute to the 1989 baseball comedy "Major League," which was largely filmed in Milwaukee, at tonight's game. Film star Corbin Bernsen (left) will be in attendance signing autographs. File photo. »Read Full Blog Post(6)
Usher to close out Summerfest July 6
Usher isn't playing any shows in the United States this summer except for one: Summerfest on closing night.
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9th baltic sea tourism forum 2016
October 19-20 2016
in Pärnu/Estonia
9th Baltic Sea Tourism Forum 2016 in Pärnu / Estonia
Programme of the 9th Baltic Sea Tourism Forum 2016
9 BSTF Preliminary Programme 2016 pdf (draft as of: Sep 01, 2016)
9 BSTF Practical Information 2016 pdf (as of: Sep 06, 2016)
9th BSTF 2016 - go to registration...
Tourism Networking Village
Since 2012, the Baltic Sea Tourism Forum has also developed into a market for new project initiatives and ideas. With the Tourism Networking Village (TNV) a new framework for exchange has been developed and should be further established in Pärnu to become an integral part of the annual forum. The TNV gives funding programmes, project initiatives and interested organisations the possibility to present themselves with a stand during the two conference days. The idea is to promote the exchange of new and ongoing project initiatives in BSR tourism at transnational level to stimulate future cooperation. It should contribute to the basic idea of the forum to actively support the exchange of practitioners in the BSR and to foster communication and cooperation among them. >> 9th BSTF TNV Registration form (pdf)
Contact Point of the 9th Baltic Sea Tourism Forum 2016
Send your questions, comments and recommendations to:
Mecklenburg-Vorpommern Tourist Board
Mr Johannes Volkmar
Project Manager International Marketing
Konrad-Zuse-Straße 2
18057 Rostock, Germany
phone +49 381 40 30 663
fax +49 381 40 30 555
mail j.volkmar[at]auf-nach-mv[dot]de
web www.off-to-mv.de
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