FIELD OF THE INVENTION 
     The invention relates to a device for branching off a fluidic partial flow from a main flow by a hydraulic pump working according to the displacement principle. The device has individual main chambers sealed off from one another and divided into functional groups by which fluid coming from at least one main flow inlet can be transported from the inlet side or suction side to the outlet side or pressure side of the hydraulic pump and further by at least one main flow outlet. 
     BACKGROUND OF THE INVENTION 
     Hydraulic pumps (see, e.g., DE 21 14 202 C3) of this type are known in the prior art in a plurality of embodiments. Generally, hydraulic pumps are used to convert mechanical energy in the form of torque and rotational speed into hydraulic energy with a definable volumetric flow and fluid pressure. Hydraulic pumps that work according to the displacement principle have individual chambers sealed in the pump housing. In these chambers fluid is transported from the inlet side of the pump, comprising a suction port, to the outlet side in the form of the pressure port. Since no direct connection is between the suction port and the pressure port, pumps according to the displacement principle are suitable especially for high fluid system pressures. 
     Depending on whether vanes or pistons are used for implementation of the displacement principle, gear pumps and spiral pumps are distinguished from the vane pumps as dictated by design. Vane pumps are distinguished from the radial and axial piston pumps. All these pumps, regardless of whether the displacement volume is kept constant or variable, the displaced volume commonly and certainly always relates only to a fluid flow that is to be delivered and that is hereinafter referred to as the main flow. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide an improved device for branching of a fluidic partial flow from a main flow by a hydraulic pump such that the range of application of these devices with a hydraulic pump is expanded in a cost-effective manner. 
     This object is basically achieved by a device that enables the branching off of a fluidic partial flow from a main flow. For the transport of the partial flow, at least one independent partial chamber in addition to the main chambers is designed for conveyance of the main flow. The partial chamber is a component of the pressure side of the hydraulic pump and is connected to an independent partial flow outlet that is separated from the respective main flow inlet and the respective main flow outlet. 
     The branched-off partial flow from the main flow allows use of the partial flow for the most varied tasks. Both the fluid volume of the partial flow and its fluid pressure are definable depending on the design of the device. This fluidic partial flow can therefore be used independently of the main flow for the supply of individual fluidic consumers. Emergency supply of hydraulic components in the field of roll stabilization or emergency supply of steering assist systems in case of failure is also easily possible via the partial flow. Furthermore, the partial flow that is branched off from the main flow can be subjected to sensor checking, for example, can be analyzed for the degree of its fouling to obtain qualitative information about the main flow. Here, a plurality of applications in the most varied areas is possible. 
     In one especially preferred embodiment of the device according to the invention, the hydraulic pump is a vane pump. Preferably, the individual vanes of the vane pump are guided in a drivable rotor to be able to move lengthwise between an end position in the rotor and an enclosing wall of a stator. The enclosing wall limits the travel of the vanes to the outside such that for at least one part of the vanes, two opposite fluid spaces at a time between the vanes and the rotor and the stator are formed. As a result of the opposite fluid spaces, depending on their volumetric configuration for different applications, different pressure levels can be implemented by one device. This configuration also leads to further possibilities of adaptation to requirements of the hydraulic circuit for the main flow. 
     The device according to the invention, however, need not be limited to use in a vane pump. Essentially all hydraulic pumps can be used here that work according to the displacement principle or a comparable principle. 
     The device according to the invention for partial flow formation with optionally definable volumetric portion, depending on the design of the device, is preferably made as a module that can be combined with other components such as, for example, drive units and/or filter units, with the formation of integral fluidic devices. The device can also be used as an individual module in complete systems such as for roll stabilization, steering support, etc., where independent partial volumetric flows are required for diverse control tasks and for emergency functions. 
     Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring to the drawings that form a part of this disclosure and that are schematic and not to scale: 
         FIG. 1  is a side elevational view in section of essential components of a device according to an exemplary embodiment of the invention, the bottom edge of the figure being shown partially cut off for the sake of simplicity; 
         FIG. 2  is an exploded perspective view of the device of  FIG. 1 , but in a plane of the figure offset thereto; 
         FIG. 3  is a bottom plan view of the chamber block of the device of  FIGS. 1 and 2 ; and 
         FIG. 4  is a perspective view in section of one possible application example for the device of  FIGS. 1 to 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The device shown in  FIGS. 1 to 3  is used for branching off a fluidic partial flow from a main flow by a hydraulic pump  10  working according to the displacement principle. The pump  10  has individual chambers  12 ,  14 ,  16 ,  18 , and  20  that are sealed off from one another. By those chambers, fluid can be transported from the inlet side or suction side to the outlet side or pressure side of the hydraulic pump  10 . 
     For the partial flow to be branched off, an independent partial chamber  26  is a component of the pressure side of the hydraulic pump  10  together with the third chamber  16 , the fourth chamber  18 , and the fifth chamber  20 . The first chamber  12  and the second chamber  14  are assigned to the suction side. 
     In the present case, the hydraulic pump  10  is a vane pump whose direction of rotation is shown with an arrow  28  in  FIG. 3 . The individual vanes  30  of the vane pump are guided in a drivable rotor  32  to be able to move lengthwise between an end position in the rotor  32  and an enclosure wall  34  of a stator  36 . Enclosure wall  34  limits the travel of the vanes  30  to the outside such that for the vanes  30  two opposite fluid spaces  38 ,  40  at a time are formed between them and the rotor  32  and the stator  36 . 
     As further follows from  FIG. 3 , viewed in the direction of rotation, the right fluid space  38  and the fluid spaces  40  widen and thus apply a suction action to the main fluid volumetric flow with inclusion of the individual chambers  12  and  14 . Conversely, viewed in the direction of  FIG. 3 , in the direction of rotation of the vane pump, the fluid spaces  38  and  40  taper relative to the chambers  16 ,  18 , and  20  so that the main flow travels to the outlet side or pressure side with a definable pressure level. This displacement principle is known in connection with vane pumps and comparable positive displacement pumps so that it will not be further detailed here. As a result of the individual chambers together with the fluid spaces  38  and  40  both on the suction side and on the pressure side for the individual chambers  12  relative to  14  as well as  16  and  18  relative to  20 , a different paired pressure level can be set so that two main flows separated from one another could be triggerable by the device. In this exemplary embodiment, however, only one main fluid flow is conveyed jointly with the chambers  12 ,  14 ,  16 ,  18 , and  20 . 
     To form the fluidic partial flow, the partial chamber  26  used is separated in space from the other indicated chambers and has a separate partial flow outlet  42 . The partial flow quantity is discharged via the indicated partial flow outlet  42  and is pushed out of the device by the respective vane  30  in the travel direction to the second fluid space  40 . Since the vanes  30  cross the partial chambers  26  in direct succession, fluid is permanently discharged to the outside on the pressure side of the device via the partial flow outlet  42 . In this exemplary embodiment, after supplying a hydraulic consumer, for performing an emergency function, or after passing through a sensor unit (not shown), the partial flow is brought to the suction side of the device and in turn delivered to the device via the partial flow inlet  44 . 
     Overall, one part of the fluid spaces  38 ,  40  is assigned to the individual chambers  12 ,  14 ,  16 ,  18 , and  20  of the suction side and the pressure side of the hydraulic pump  10  and that another part, formed by at least one of the fluid spaces  40 , is assigned to the partial chamber  26  for partial flow formation. As the exploded drawing in  FIG. 2  shows in particular, the stator  36  is formed from a hollow cylindrical ring accommodated in a housing  46  of the device. The rotor  32  with its individual vanes  30  is held eccentrically with its drive axis in the stator  36  for purposes of implementing the already described vane pump principle. The illustrated chambers  12 ,  14 ,  16 ,  18 ,  20 , and  26  are in turn a component of an independent chamber block  48 . For the sake of simplicity the fourth chamber  18  is not shown in  FIG. 2 . The chamber block  48  ends to the outside flush with the device housing  46  (compare  FIG. 1 ) and is sealed accordingly to the inside in the direction of the stator  36  by a gasket  50 . Another gasket  52  is on the side opposite the chamber block  48  for sealing of adjoining parts of the device. 
     For driving the vane pump, a drive shaft  54  is used that is sealed to the outside by a chambered gasket  56 , and by an independent gasket  58  relative to a drive shaft  60  of an electric motor  62  (compare  FIG. 4 ). As illustrated in  FIG. 2 , the partial flow outlet  42  is shown offset in the plane of the figure by a pivot angle of approximately 120° compared to  FIG. 1 . 
     As the figures furthermore show, the chambers  12 ,  14 ,  16 ,  18 , and  20  discharge from the suction side  22  and the pressure side  24  within the chamber block  48  to its two opposite face sides  64 ,  66  into the environment. The partial chamber  26  for partial flow formation, on its side facing away from the hydraulic pump  10  is closed to the outside by wall parts  68  of the chamber block  48  ( FIG. 1 ). Furthermore, the individual chambers  12 ,  14 ,  16 ,  18 , and  20  as well as  26  are arranged running in a concentric configuration to the drive axle (drive shaft  60 ) of the hydraulic pump and are otherwise made sickle-shaped. The first chamber  12  with the third and fourth chambers  16  and  18  forms the outer concentric ring. The second chamber  14  with the fifth chamber  20  and the partial chamber  26  lies on the inner concentric circular path around the drive axis. If other positive displacement pumps are to be used for the hydraulic pump  10 , a different arrangement must be chosen. For separating the partial flow from the main flow, an independent branch chamber is necessary for this purpose with a separate outlet relative to the inlets and outlets for the main flow. 
     One exemplary embodiment for the application of the described device is shown below based on  FIG. 4 . Here, the device shown in  FIGS. 1 and 3  is seated on a filter unit  70  of conventional design. The filter unit  70  has a replaceable filter element  72  in a filter housing  74 . The filter mat  76  of the filter element  72  on the inner peripheral side is supported by a conventional support pipe  78  with inside walls  80  arranged in a star-shape. Furthermore, the filter unit  70  on its top has a fluid inlet  82  and a fluid outlet  84  that route the main flow. Furthermore, the filter unit  70  has a bypass device  86  that directly clears the fluid path between the device according to the invention and the fluid outlet  84  if the filter element  72  is blocked as a result of dirt. 
     Opposite the filter unit  70  and seated from above on the device according to the invention, the electric motor  62  is provided. For the sake of simplicity, the electrical winding of the motor has been omitted. The electric motor  62  drives the drive shaft  60 . In the direction of  FIG. 4 , shaft  60  engages the rotor  32  of the vane pump with its bottom end in order to ensure its driving in this way. If the vane pump is being operated as a hydraulic pump  10 , it intakes fluid via its suction side and therefore via a main flow inlet  22  via the fluid inlet  82 . On the pressure side and therefore via the main flow outlet  24 , the pertinent amount of fluid of the main flow is delivered via a passage site  88  (compare  FIG. 1 ) into the fluid space  90  between the filter housing  74  and filter element  72 . After flowing through the filter element  72  from the outside to the inside via the wall guide of the support pipe  78 , the cleaned fluid is routed out of the device via the fluid outlet  84 . At the same time, in this delivery operation for the main flow, secondary flow fluid is intaken via the partial flow inlet  44 , for example, originating from a sensor device, and via the separate partial chamber  26  and the partial flow outlet  42  in turn relayed to the sensor device (not shown), for example, for determining the degree of fouling of one part of the fluid of the main flow. 
     The above described exemplary embodiment is only exemplary, and the device according to the invention can be used wherever a partial flow amount is required from a main flow. In this way, emergency functions in roll stabilization devices in the motor vehicle and/or steering assist devices can also be provided with partial flow fluid. 
     While one embodiment has been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.
A device for branching a fluidic partial flow off a main flow by a hydraulic pump ( 10) includes individual main chambers ( 12, 14, 16, 18, 20) sealed from each other and divided into functional groups, and operates according to the displacement principle. The chambers enable fluid from at least one main flow inlet ( 22) to be transported from an inlet or suction side to an outlet or pressure side of the hydraulic pump ( 10) and then via at least one main flow outlet. At least one independent partial chamber ( 26) is provided for the transport of the partial flow in addition to the main chambers ( 12, 14, 16, 18, 20). The partial chamber forms part of the pressure side of the hydraulic pump ( 10) and is connected to an independent partial current outlet ( 42) separate from the main flow inlet ( 22) and the main flow outlet ( 24).