Abstract:
An integrated, i.e unitary, rotary hydraulic vane pump assembly reduces cost and simplifies manufacturing thereof. The integrated assembly includes an electric motor, a rotary vane pump, a pump housing and an end bell. The end bell has an inlet fitting or passageway which communicates with the inlet of the rotary vane pump. The pump housing receives the vane pump and is received within the end bell. The electric motor is secured to the face of the pump housing opposite the end bell. The pump housing includes outlet passageways and a centrally disposed axial opening for receiving an output shaft of the electric motor. The rotary vane pump includes end sections and a center, cam ring section which receives a vane rotor assembly coupled to the output shaft.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates generally to hydraulic rotary vane pumps and more specifically to a hydraulic rotary vane pump assembly having an integrally mounted drive motor and rotary vane pump. 
     2. Description of Related Art 
     In order to improve the operation and efficiency of power steering systems utilizing pressurized hydraulic fluid a current design approach utilizes a hydraulic rotary vane pump directly driven by a variable speed electric motor. Such electro-hydraulic power steering systems (EHPAS) provide improved steering feel, sensitivity, control and reduced energy consumption. 
     The packaging of such devices, i.e., a dedicated electric motor and hydraulic rotary vane pump, has yet to reach a level of sophistication commensurate with other components of the system. That is, present designs, simply comprehend a cartridge type rotary vane pump mounted upon appropriate stationary vehicle components and an adjacent and operatively associated electric motor similarly secured. In this configuration the pump has its own housing, the motor has its own housing, a coupler for the pump and motor shafts is required and various brackets and fasteners for mounting the pump and motor are required. 
     Clearly a motor and pump assembly of this type does not represent an efficient package from weight, space and cost standpoints. The current invention relates to an improvement in such assemblies wherein reduced weight and manufacturing simplicity are two of the many benefits enjoyed. 
     SUMMARY OF THE INVENTION 
     An integrated, i.e. unitary, rotary hydraulic vane pump assembly reduces cost and simplifies manufacturing thereof. The integrated assembly includes an electric motor, a rotary vane pump, a pump housing and an end bell. The end bell has an inlet fitting or passageway which communicates with the inlet of the rotary vane pump. The pump housing receives the vane pump and is received within the end bell. The electric motor is secured to the face of the pump housing opposite the end bell. The pump housing includes outlet passageways and a centrally disposed axial opening for receiving an output shaft of the electric motor. The rotary vane pump includes end sections and a center, cam ring section which receives a vane rotor assembly coupled to the output shaft. 
     Thus it is an object of the present invention to provide an integrated, i.e. unitary, rotary vane pump and motor assembly. 
     It is a further object of the present invention to provide an integrated hydraulic rotary vane pump and motor assembly having common components and features which reduce weight and simplify manufacturing. 
     It is a still further object of the present invention to provide an integrated rotary hydraulic vane pump assembly disposed within a housing to which an electric drive motor is attached. 
     Further objects and advantages of the present invention will become apparent by reference to the following description of the preferred embodiment and appended drawings wherein like reference numbers refer to the same component, element or feature. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an integrated rotary vane pump and motor assembly according the present invention; 
     FIG. 2 is a full sectional, exploded view of the integrated rotary vane pump and motor assembly according to the instant invention; 
     FIG. 3 is an enlarged, full sectional view of a pump housing of the integrated rotary vane pump and motor assembly according to the present invention; and 
     FIG. 4 is an enlarged, full sectional view of a rotary vane pump of an integrated rotary vane pump and motor assembly according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIGS. 1 and 2, an integrated rotary vane hydraulic pump and motor assembly is illustrated and generally designated by the reference number  10 . The integrated pump and motor assembly  10  includes an electric motor  12  having an electrical fitting  14  such as a removable connector or seal and an electrical cable  16  which provides electrical energy to the motor  12 . Axially extending from the motor  12  is an output shaft  18  having a region of male splines  22  formed thereupon. Adjacent the end of the output shaft  18  is a reduced diameter portion  24 . 
     Referring now to FIGS. 1 and 3, the electric motor  12  is attached by suitable fasteners (not illustrated) which preferably extend axially through the electric motor  12  to a pump housing  30 . The pump housing  30  includes a cylindrical lip or projection  32  which locates and engages the electric motor  12  and a centrally disposed through passageway  34  which receives the output shaft  18  of the electric motor  12 . A first counterbore  35  concentric with the through passageway  34  receives a fluid tight shaft seal  36 . A second counterbore  38  is disposed adjacent the end of the through passageway  34  opposite the first counterbore  35 . The pump housing  30  also includes a large cylindrical extension  40  which defines an interior cylindrical volume  42  which communicates with an annular outlet chamber  44 . The annular outlet chamber  44  is in fluid communication with a radial outlet passageway  46  which provides power steering fluid under pressure to associated power steering components (not illustrated). Preferably, the radial outlet passageway terminates in a threaded opening  48  which is adapted to receive a complementarily threaded male fitting. 
     As illustrated in FIGS. 1 and 2, the pump housing  30  is received within an end bell assembly  50 . The end bell assembly  50  includes a generally planar base  52  having a plurality of mounting holes  54  which receive suitable fasteners (not illustrated) which secure the pump and motor assembly  10  to a suitable feature or component of a motor vehicle. The end bell assembly  50  also includes a cylindrical portion  56  having an inlet opening  58  which is adapted to receive an inlet fitting such as an elbow  60  or other suitable component adapted to accommodate an inlet hose or other fluid carrying component which provides power steering fluid to the inlet opening  58  of the pump and motor assembly  10 . An O-ring seal  62  is received within a suitably sized and located circular channel or groove  64  in the pump housing  30  and provides a fluid tight seal between the cylindrical portion  56  of the end bell assembly  50  and the pump housing  30 . A plurality of ears or lugs  66  extend radially from the cylindrical portion  56  and are engaged by a like plurality of threaded fasteners  68  extending through a plurality of ears or lugs  69  extending from the pump housing  30 . Cooperation between the threaded fasteners  68  and the lugs  66  secures the pump housing  30  and the electric motor  12  to the end bell assembly  50 . 
     Referring now to FIGS. 2 and 4, the integrated pump and motor assembly  10  also preferably includes a cartridge type rotary vane pump assembly  70 . While a cartridge type rotary vane pump assembly  70  is described herein, it will be appreciated that such description is illustrative and exemplary only and that other types and configurations of rotary vane pumps may be utilized in the present invention. The cartridge type rotary vane pump assembly  70  includes a first or base section  72  which, through the agency of a first  0 -ring seal  74  and a second O-ring seal  76 , seals against aligning surfaces of the pump housing  30  such that high pressure, outlet flow through a pair of outlet passageways  78  in the first section  72  is directed into the outlet annulus  44  without leakage. 
     The rotary vane pump assembly  70  also includes a rotor  80  having a splined interior passageway  82  and a plurality of radial slots  84  which open around its periphery and receive a like plurality of vanes  86 . The rotor  80  and the vanes  86  are received within a cam ring  90  having an interior surface  92  which defines a pumping chamber  94 . The interior surface  92  has alternating larger and smaller diameter regions of dwell and intermediate regions of increasing and decreasing diameter which define intake and pumping regions, respectively. A pair of parallel spaced-apart axial passageways  96  extend through the cam ring  90 . 
     A second or top section  100  completes the pump assembly  70  and includes a through opening  102  which receives the reduced diameter portion  24  of the shaft  18 . The top section  100  also includes a pair of parallel through axial passageways  104  which receive a pair of mounting rods or pins  106  which seat within the first section  72  and receive retaining spring clips  108  such as Tinnerman nuts or similar spring fasteners which secure the components of the pump assembly  70  together. The top section  100  also defines a pair of inlet or intake ports  110 , one of which is illustrated in FIG.  4 . 
     Referring now to FIGS. 2 and 3, at the interface between the pump housing  30  and the rotary vane pump assembly  70  and received within the second counterbore  38  is a needle bearing assembly  112 . The needle bearing assembly  112  freely rotatably supports the output shaft  18  of the electric motor  12  in the region between the electric motor  12  and the rotary vane pump assembly  70 . Adjacent the needle bearing assembly  112  is a Belleville washer  114  which seats within a stepped portion  116  of the first or base section  72  of the rotary vane pump assembly  70 . It will be appreciated that it is necessary for the rotary vane pump assembly  70  to be restrained against rotation within the cylindrical volume  42  of the cylindrical extension  40 . This may be readily achieved by forming one or more axially oriented keyways in the interior surface of the cylindrical extension  40  and including one or more complementarily sized and configured projections on one or more of the sections of the rotary vane pump assembly  70 . A snap ring may be utilized to retain the rotary vane pump assembly  70  within the cylindrical extension  40 . Alternatively, one or more radially oriented pins may be disposed in radial opening in the wall of the cylindrical extension  40  to engage and restrain the rotary vane pump assembly  70  against both axial and rotational motion. 
     Preferably, the integrated pump and motor assembly  10  also includes a bypass or pressure relief valve assembly  120 . The pressure relief valve assembly  120  is received within a threaded passageway  122  which is in fluid communication with the radial outlet passageway  46  in the pump housing  30 . The pressure relief valve assembly  120  includes a cylindrical body  124  having an axial passageway  126  in fluid communication with the threaded passageway  122  and at least a pair of opposed radial ports  128 . A ball bearing  132  or similar device is biased by a compression spring  134  against a valve seat  136  and both components are retained within the cylindrical body  124  by a plug or cap  138 . As pressure within the radial outlet passageway  46  increases beyond a predetermined limit, the ball bearing  132  is lifted off the seat  136  and power steering fluid flows past the ball bearing  132 , out the radial ports  128  and into the interior of the cylindrical portion  56  of the end bell housing  50 . 
     In operation, the integrated vane pump and motor  10  according to the present invention receives return hydraulic or power steering fluid through the inlet elbow  60  and the inlet opening  58  which fills the cylindrical portion  56  of the end bell assembly  50  around the cartridge type rotary vane pump assembly  70 . Fluid is drawn into the rotary vane pump assembly  70  through the inlet or intake ports  110 . The hydraulic or power steering fluid is pumped by the vanes  86  in the rotor  80  and exits the rotary vane pump assembly  70  under high pressure through the outlet passageways  78 , through the outlet annulus  44  and out through the radial outlet passageway  46 . As noted previously, should pressure in the outlet passageway  46  rise above a predetermined maximum, the pressure relief valve assembly  120  relieves such pressure and allows hydraulic or power steering fluid to return to the interior of the cylindrical portion  56  of the end bell assembly  50 . 
     The foregoing disclosure is the best mode devised by the inventors for practicing this invention. It is apparent, however, that apparatus incorporating modifications and variations will be obvious to one skilled in the art of rotary vane pumps. Inasmuch as the foregoing disclosure presents the best mode contemplated by the inventors for carrying out the invention and is intended to enable any person skilled in the pertinent art to practice this invention, it should not be construed to be limited thereby but should be construed to include such aforementioned obvious variations and be limited only by the spirit and scope of the following claims.