Abstract:
The invention relates to a vane-cell pump comprising a pump rotor ( 20 ), provided with a radially displaceable rotor blade ( 22 ). Said pump rotor is mounted in a pump stator ( 12 ) which can be pivoted inside a pump bearing house ( 10 ) around a stationary pivotal axis ( 34 ) in a radial position with regard to said pump rotor. A control device ( 30 ) is associated with the pump stator ( 12 ) for automatic pressure adjustment. Said control device has an actuating member protruding on the outside, therefrom, perpendicular to the pivotal axis thereof. The actuating member forms a pivoting piston ( 38 ) in a guide element ( 10 ) of the pumpbearing housing ( 10 ) which is directly impinged upon by a pumping medium. The pivotable piston can pivot in a direction against the action of a pressure spring ( 50 ).

Description:
DESCRIPTION  
         [0001]    The invention concerns a vane-cell pump having the features of the pre-characterizing part of claim 1.  
           [0002]    DE 33 33 647 A1 discloses a vane-cell pump having these structural features whose construction guarantees that the amount and pressure of a liquid medium to be supplied, e.g. lubricant for pressure lubrication, are automatically adjusted to the requirements and the respective state of a unit to be lubricated, e.g. a combustion engine.  
           [0003]    Towards this end, the stator, which can be pivoted radially relative to the rotor for pressure control, is correspondingly displaced by an actuator. An actuating piston of the pressure regulating device is guided in a guiding cylinder of the pump bearing housing and acts on the actuator. The cylinder space is thereby in permanent communication with the pressure side of the vane-cell pump via a channel. The pressure regulating device has at least one pressure spring, forming a stop and acting on the actuator as a counter force in opposition to the piston. It is supported on one side by the bottom of a further guiding cylinder which is coaxial to the guiding cylinder of the actuating piston, and on the other side by a counter piston guided therein and communicating with the actuator.  
           [0004]    Corresponding pretension of the pressure spring of the pressure regulating device adjusts the supply pressure in dependence on the spring characteristics.  
           [0005]    The pressure regulating device of this known vane-cell pump requires a significant degree of technical and assembly effort with a correspondingly large amount of space being required for accommodating the two coaxially guided actuating and counter pistons in the pump bearing housing.  
           [0006]    It is therefore the underlying purpose of the invention to substantially simplify the construction of the pressure regulating device for vane-cell pumps of the type mentioned in claim 1.  
           [0007]    This object is achieved by the characterizing features of claim 1.  
           [0008]    In the inventive construction, the pressure regulating device comprises only one actuator in the form of a pivot piston guided in the guide of the pump bearing housing in a pressure and liquid-tight fashion which is directly loaded by the pressure medium. The stored energy can act directly as a counter force on the pump stator e.g. at a suitable location in the bearing housing.  
           [0009]    In the most simple form, the inventive construction requires only one single pressure and liquid-tight pivotable actuator for controlled pivoting of the pump stator and at least one energy accumulator which can be accommodated in the pump bearing housing at a freely selectable location relative to the pump stator.  
           [0010]    The pump stator can thereby form a one-armed or two-armed lever wherein, in the latter case, the lever arm facing away from the pump rotor can form the pivot piston.  
           [0011]    The pivot piston will preferably be operated in opposition to at least one pressure spring which is supported thereon to produce the stored energy.  
           [0012]    This accumulated energy can thereby vary to permit variable adjustment of the maximum supply pressure.  
           [0013]    This can be effected by serially switching pressure springs in steps or by providing a pressure spring which can be gradually pretensioned.  
           [0014]    The pump stator can be disposed in the bearing housing on a pivot axis which is fixed to the housing or, with a partially cylindrical hinge section provided between its two lever arms, can be brought into positive engagement with two mutually opposite bearing surfaces of the pump bearing housing which are fixed to that housing.  
           [0015]    The essential features and details of the invention can be extracted from embodiments of vane-cell pumps which are shown in the drawings in an exemplary and simplified fashion. 
       
    
    
       [0016]    In the drawing:  
         [0017]    [0017]FIG. 1 shows a cross-section through the vane-cell pump wherein illustrations a) to c) show different positions of the pump stator for adjusting the supply volume as produced by the pressure regulating device; and  
         [0018]    [0018]FIG. 2 shows a cross-section of the vane-cell pump. 
     
    
       [0019]    The vane-cell pumps shown in FIGS. 1 and 2 have identical main constructional features, having a preferably hollow-cylindrical pump bearing housing  10  whose circular cylindrical housing interior  14  accommodates a pump stator  12  and is closed at the ends by flat end faces in a manner known per se and, analogous to the construction of DE 33 33 647 A1, is connected to a pressure and suction line (not shown for reasons of simplicity).  
         [0020]    The pump stator  12  contains a circular-cylindrical rotor chamber  16  in which a rotor  20  is disposed, preferably slightly eccentrically, to be driven by the pump drive shaft  18  disposed in the end walls of the pump bearing housing  10 . Conventionally, the rotor  20  has a plurality of radially displaceable plate-like rotor blades  22  about its periphery each of whose two ends engages one circular guiding path  24  in the rotor chamber  16  which are provided on both chamber end walls of the rotor chamber  16  which are mutually coaxial and stationary. The guiding paths  24  are preferably defined by annular collars  26  which are formed on the end walls of the rotor chamber  16 .  
         [0021]    Cooperation between the guiding paths  24  and the blade ends ensures that, even when the rotor has stopped, the rotor wings  22  are located in a radial position with respect to the peripheral wall  28  of the rotor chamber  16  to assure that a flow medium is immediately pumped when the rotor starts turning.  
         [0022]    A regulating device, referred to in its totality with  30 , serves for automatic regulation of the supply amount by means of which the position of the rotor chamber peripheral wall  28 , the annular collars  26  and the pump stator  12  can be preferably continuously varied relative to that of the rotor  20 .  
         [0023]    Towards this end, the pump stator  12  can be pivoted in the pump bearing housing  10  about a pivot axis  34  which is parallel to the rotor axis  32  and fixed to the housing.  
         [0024]    In the embodiments shown, the pump stator  12  forms a double-armed lever whose one lever arm  36  accommodates the rotor chamber  16 , while its other lever arm  38  is part of the regulating device and serves the function of a pivot piston for pivoting the pump stator  12 .  
         [0025]    This pivot piston  38  is sector-shaped and guided in a guiding housing part  10 ′ formed about the periphery of the pump bearing housing  10  in a pressure and liquid-tight fashion wherein the separation between its piston outer surface  40  and pivot axis  34  determines its radius of curvature.  
         [0026]    The part  12 ′ of the pump stator  12  which is provided in the transition region of the two lever arms  36  and  38  and which accommodates the pivot axis  34 , abuts with a corresponding partially circular convex curvature  42  on a complementary wall part  44  of the guiding housing part  10 ′ in a pressure and liquid tight fashion thereby forming a pressure space  46  for the loading of the pivot piston  38  with a flow medium which is in permanent communication with the pump pressure side (at  48 ) via a connecting or regulating channel (not shown for reasons of clarity).  
         [0027]    An energy storing means, preferably in the form of at least one pressure spring  50 , is disposed on the piston side opposite to the pressure space  46  and is supported on the pivot piston  38  for generating the counter force required for regulation. The other end of the pressure spring  50  abuts a corresponding wall part of the guiding housing part  10 ′ to urge the pump stator  12  towards a pivoted position relative to the pump rotor  20 , i.e. towards the stop position in the interior  14  of the pump bearing housing  10  having maximum pump output (see FIG. 1 a )).  
         [0028]    The regulation device  30  thereby ensures that the supply amount and the work pressure are automatically adjusted to the given requirements.  
         [0029]    The illustration b) of FIG. 1 shows e.g. the automatic setting of the pump stator  12  if only half the pump output is required in correspondence with the conditions.  
         [0030]    The representation c) shows setting of the pump stator  12  with an output of zero.  
         [0031]    The embodiment of the vane-cell pump of FIG. 2 has a sole structural difference concerning the pivot bearing and the part  12 ′ of the double-armed pump stator  12  which receives the pivot axis  34 . In this case, the stator part  12 ′ forms a partially cylindrical hinged section which positively engages two mutually opposed segment-shaped bearing surfaces formed on the pump bearing housing  10 , one of which is formed by the wall part  44  of the pump bearing housing  10 ′ and the other is labelled with  52 . It is thereby important that the bearing overlap is &gt;180°.  
         [0032]    Clearly, this invention can be applied to vane-cell motors in the same advantageous fashion.