The power steering pump 10 further includes a cover 30. As illustrated the cover 30 is disposed within the open end 20 of the housing 12 adjacent and contacting the cam plate 22. The outer circumferential surface 32 of the cover 30 includes a groove 34 sized to receive a seal member, such as an O-ring 36, see
As illustrated in
The outlet ports 44, 46 include first 70 and second 72 portions. The portions 70, 72 are adjacent with the second portion 72 located radially outward from the first portion 70. As illustrated the first and second portions 70, 72 are grooves or channels in the planar side surface 66. The grooves or channels having opposing sidewalls 74, 76 extend axially inward into the cover 30 from the planar side surface 66.
As illustrated in
The cover 30 also includes two pairs of passages 48, 50, 52, 54. As illustrated in
As illustrated, all of the under vane porting, including the passageway or fluid conduit 56 extending between the outlet port 44 and the fluid passage 48 is contained within the cover 30. The term under vane porting is used herein to describe the ports or passageways used to transfer or enable fluid communication with the under vane cavities located in the rotor 26. Under vane pressure is used to lift or force the vanes outward against the cam profile of the cam chamber 24 allowing the pump 10 to do work on the power steering fluid.
Depending upon the cover 30 configuration, it may be necessary to deepen or extend a portion 52a, 54a of the fluid passage 52, 54 further into the cover 30 such that the passageways or fluid conduits 56 connect with the respective extended portions 52a, 54a of the fluid passages 52, 54. For example, the portions 52a, 54a of the fluid passages 52, 54 may include an axially extending bore. The axially extending bore 52a, 54a may be necessary as use of a conventional boring tool such as a drill may limit the angle of the passageway or fluid conduit 56 with respect to the planar side surface 66 of the cover 30 based on the position of the outlet port 44 with respect to the outer circumferential surface 32 of the cover 30. In some instances it may be possible to drill or bore a passageway through the outer circumferential surface 32 of the cover 30 and into the cover 30 substantially parallel to the planar side surface 66 to connect the outlet port 44 and the fluid passage 48. However, such an assembly may be prone to leak and sealing issues and may require a plug or other seal member placed in the outer circumferential surface 32.
The fluid passages 52-54 and passageways or fluid conduits 56 are part of the under vane porting used to control the flow of fluid from the outlet ports 44, 46 to the rotor 26. As known, the rotor 26 contains a plurality of vanes that move reciprocally in radial slots located in the rotor 26. The radially outer end of each vane contacts an inner surface of the cam chamber 24. The radially inner end of each vane is located in or adjacent to a space or cavity disposed at the end of the radial slot. The space or cavity receives pressurized fluid used to urge the vane really outward against the cam surface of the cam chamber. The chambers at each end of each radial slot are aligned with and communicate with the passageways 48-54 located in the cover 30. Accordingly, fluid from the outlet ports 44, 46 travels through the passageways or fluid conduits 56 that connect the outlet ports 44, 46 with the fluid passages 52, 54. The passageways or fluid conduits 56 hydraulically connect the vanes with the outlet ports 44, 46 and allow flow of high-pressure fluid through the under vane porting to urge the vanes outward in a radial direction against the inner surface of the cam chamber 24.
The cover 30 further includes a blind bore or socket 58 forming a support structure or assembly that receives and supports the shaft 60. Accordingly, the closed end 18 of the housing 12 supports one portion of the shaft 60 while the blind bore or socket 58 located in the cover 30 also supports the shaft 60. A fluid conduit 62 connects one of the inlet ports 42 with the blind bore or socket 58. Accordingly, fluid flows from the inlet port 42 to the socket 58 to provide lubrication for the shaft 60 during pump operation. In addition, the cover 30 also includes a plurality of apertures 64 used to properly align the cover 30 and correspondingly the under vane porting with the remaining elements of the power steering pump 10 including the cam plate 22, rotor 26, lower pressure plate 28 and housing 12.
Accordingly, the present invention provides a cover 30 containing an outlet port 44, fluid passage 48 and a passageway or fluid conduit 56 extending directly from the outlet port 44 to the fluid passage 48. In this manner, the cover 30 contains the outlet port and the under vane porting. In addition, the cover 30 contains a blind bore or socket machined with clearance tolerance and flow grooves for lubrication of the pump shaft 60 whereby one end or portion of the shaft 60 is supported by the cover 30.
Accordingly, in the described embodiment, a single cover 30 is utilized to seal and secure the cam plate 22 within the housing 12 without the need for a upper pressure plate. Reducing the part count removes potential leak paths and eliminates the need for precision grinding of mating surfaces.
The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.