Eccentric bearing assembly

• US 5,785,430 A
• Filed: 12/16/1996
• Issued: 07/28/1998
• Est. Priority Date: 12/16/1996
• Status: Expired due to Fees

• Current Assignee: General Motors Corporation (General Motors Company)
• Original Assignee: General Motors Corporation (General Motors Company)
• Inventors: Bright, James Arthur, Chang, Huang-Tsang
• Primary Examiner(s): Hannon, Thomas R.
• Application Number:
  US08/766,078
• Time in Patent Office: 589 Days
• Field of Search: 384/548, 384/549, 384/569, 384/588, 384/447, 384/449, 417/273, 91/491
• US Class Current: 384/447
• CPC Class Codes: B60T 8/4031 Pump units characterised by their construction or mounting pump units in combination with valve blocks B60T8/36
• CPC Class Codes: F04B 1/0426 Arrangements for pressing the pistons against the actuated cam; Arrangements for connecting the pistons to the actuated cam
• CPC Class Codes: F16C 3/22 Cranks; Eccentrics constructional features of crank-pins F16C11/02

Abstract

An efficient, cost effective eccentric bearing assembly is provided for use in a multiple piston hydraulic pump. The eccentric bearing assembly includes a roller bearing having an annular race. The race includes a groove around its outside perimeter. The groove engagably receives parti-spherical faces of a pair of opposed pistons. The parti-spherical face evenly loads the race and rollers as the race reciprocates with the eccentric. The invention avoids the use of rotating thrust bearings and instead axially supports the piston clip with stationary surfaces. Placement of the parti-spherical face or an optional conical face, at the interface between the pistons and the grooved race maintains the sliding contact point for piston intake strokes near the center of the face.

Claims

1. An eccentric bearing assembly comprising:

a shaft rotatable about a first center and including an eccentric on the shaft that rotates about a second center that is offset from the first center;

first and second opposed pistons disposed so that the shaft extends perpendicularly between the pistons, with the eccentric aligned between the pistons;

an annular bearing assembly encircling the eccentric and including a plurality of rollers engaging the eccentric that are carried in a race, wherein the race includes a radially outer perimeter with an annular groove;

wherein the pistons each include a face that is shape conformed to the groove; and

a clip that reaches around the bearing and engages each of the pistons maintaining the piston faces in the groove and in engagement with the race;

wherein, as the shaft rotates, the eccentric turns within the bearing and effects reciprocating linear movement of the pistons with a point contact being maintained between the piston ends and the race, maintaining a centered load on the race.

2. An eccentric bearing assembly according to claim 1 wherein an axial position of the annular bearing assembly on the shaft is maintained solely by the shape conformed engagement between the pistons and the race.

3. An eccentric bearing assembly according to claim 2 wherein when the shaft rotates in a first direction the race rotates in a second direction that is opposite the first direction.

4. An eccentric bearing assembly according to claim 2 wherein the clip is rotatable on the pistons about a lateral center and is alternately engageable with the body and a non-rotatable washer wherein the body and the washer limit rotation of the clip.

5. An eccentric bearing assembly according to claim 2 wherein the race carries the plurality of rollers that are engaged with the eccentric and wherein maintenance of the centered load on the race provides a substantially even force distribution on the rollers.

6. An eccentric bearing assembly according to claim 1 further comprising a motor supporting and rotating the shaft, wherein the pistons generate an output pressure, wherein a load is exerted on the motor in rotating the shaft to generate the output pressure, wherein the load operates with a peak efficiency minimizing a current load on the motor when the output pressure is within the range of two thousand to twenty-five hundred pounds per square inch.

7. An eccentric bearing assembly for operation in generating a hydraulic output pressure comprising:

a body having a longitudinal bore and a lateral bore intersecting the longitudinal bore wherein the lateral bore is substantially perpendicular with the longitudinal bore, with a coexistent area defined by an intersection of the longitudinal and lateral bores, wherein the longitudinal bore includes a blind end;

a motor engaging the body within the longitudinal bore, the motor including a rotatable shaft extending through the coexistent area, the shaft including a terminal end and an eccentric;

a bearing positioned in the blind end of the longitudinal bore and rotatably supporting the terminal end of the shaft;

a non-rotatable washer supported by the motor and having an opening wherein the shaft extends through the opening;

an annular bearing assembly positioned in the coextensive area and having a plurality of rollers engaging the eccentric with a race surrounding the rollers wherein the race includes a radially outer perimeter with an annular groove;

first and second pistons positioned in the lateral bore on opposite sides of the shaft wherein the pistons each include a end with a face that is shape conformed with the groove and wherein the faces engage the race in the groove; and

a semi-annular clip reaching around the annular bearing assembly and engaging the pistons and maintaining engagement between the pistons and the race, wherein the clip is rotatable about a lateral axis that extends through the center of the lateral bore and wherein rotation of the clip is limited by the non-rotatable washer and the blind end of the bore;

wherein the pistons exert a load on the race that is substantially centered on the rollers regardless of perpendicularly variances between the pistons and the race due to the shape conformed nature of the faces and the groove.

8. An eccentric bearing assembly for operation in developing a hydraulic output pressure comprising:

a body having a longitudinal bore and a lateral bore intersecting the longitudinal bore wherein the lateral bore is substantially perpendicular with the longitudinal bore, with a coexistent area defined by an intersection of the longitudinal and lateral bores, wherein the longitudinal bore includes a blind end;

a motor engaging the body within the longitudinal bore, the motor including a rotatable shaft extending through the coexistent area, the shaft including a terminal end and an eccentric;

a bearing positioned in the blind end of the longitudinal bore and rotatably supporting the terminal end of the shaft;

a non-rotatable washer supported by the motor and having an opening wherein the shaft extends through the opening;

an annular bearing assembly positioned in the coextensive area and having a plurality of rollers engaging the eccentric with a race surrounding the rollers wherein the race includes a radially outer perimeter with an annular groove with a smoothly curved concave profile;

first and second pistons positioned in the lateral bore on opposite sides of the shaft wherein the pistons each include a end with a face that is parti-spherical to be shape conformed with the groove, wherein the face includes a center at a lateral axis and wherein the faces engage the race in the groove; and

a semi-annular clip reaching around the annular bearing assembly and engaging the pistons and maintaining engagement between the pistons and the race, wherein the clip is rotatable about the lateral axis that extends through the center of the lateral bore and wherein rotation of the clip is limited by the non-rotatable washer and the blind end of the bore;

wherein when the rotatable shaft rotates, the eccentric turns within the race effecting reciprocating linear movement of the pistons with a point contact being maintained between the piston faces and the race at the lateral axis.