Compact eccentric-driven pump for a controlled braking system

Abstract

An eccentric-driven piston pump for a vehicle controlled braking system has a pump drive apparatus including a stub shaft having an eccentric journalled in a pump housing for self-supported rotation about a stub shaft axis by a first and a second rotating bearing disposed on opposite axial sides of the eccentric. The stub-shaft is operatively connected to the rotating drive shaft of a motor, and the eccentric is connected for imparting reciprocating motion to the pistons. A pair of thrust bearings including a counterweight for balancing the pump drive apparatus, are disposed on the stub shaft adjacent the eccentric at opposite axial ends thereof between the eccentric and first and second rotating bearings. The motor includes a spherical bearing for alignment of a motor drive shaft with the stub shaft, and a bushing for loosely supporting the drive shaft prior to attaching the drive shaft to the stub shaft.

We claim:  
     
         1 . A pump apparatus for a controlled braking system in a vehicle, the pump comprising: 
 a pump housing for receiving at least one pump module having a reciprocating piston with an exposed end thereof extending from the module; and    a pump drive apparatus attached to the pump housing and including a stub shaft having an eccentric between a driven end and an end of the stub shaft opposite the driven end, the stub shaft journalled within the housing for self-supported rotation about a stub shaft axis by a first and a second rotating bearing disposed on opposite axial sides of the eccentric, the driven end of the stub-shaft adapted for operative connection to a rotating drive shaft to be rotated thereby, and the eccentric adapted for operative connection to the exposed end of the piston for imparting reciprocating motion to the piston within the pump module.    
     
     
         2 . The pump apparatus of  claim 1  wherein the pump drive apparatus further includes: 
 a needle bearing mounted on the eccentric and having an outer race adapted for contacting the exposed end of the piston;  
 a pair of thrust bearings disposed on the stub shaft and abutting the needle bearing at opposite axial ends thereof between the first and second rotating bearings; and  
 a thrust washer disposed between the housing and the rotating bearing at the end of the stub shaft opposite the drive end for urging the pump drive apparatus along the stub-shaft axis in a direction away from the thrust washer.  
 
     
     
         3 . The pump apparatus of  claim 2  wherein the drive apparatus further includes a retainer element abutting one of the rotating bearings adjacent the driven end of the stub shaft and operatively connected to the housing for limiting axial movement of the stub shaft in the housing.  
     
     
         4 . The pump apparatus of  claim 2  wherein at least one of the thrust bearings includes a counterweight for balancing the pump drive apparatus.  
     
     
         5 . The pump apparatus of  claim 4  wherein the pump drive apparatus includes a motor having a rotating drive shaft extending therefrom operatively connected to the drive end of the stub shaft.  
     
     
         6 . The pump apparatus of  claim 5  wherein the motor includes a drive apparatus retainer element abutting one of the rotating bearings adjacent the driven end of the stub shaft for limiting axial movement of the stub shaft in the housing.  
     
     
         7 . The pump apparatus of  claim 5  wherein the motor does not include a counterweight for balancing the pump drive apparatus.  
     
     
         8 . The pump apparatus of  claim 5  wherein the rotating drive shaft defines an axis of rotation, a drive end adapted for operative connection to the stub shaft, and an anti-drive end, and the motor further comprises: 
 a motor housing for attachment of the motor to the pump housing;  
 a rotating drive shaft bearing attached to the motor housing for journaling the anti-drive end of the rotating drive shaft, and having a spherical outer surface thereof operatively connected to the motor housing for allowing the rotating shaft to nutate about the axis of the rotating drive shaft; and  
 a bushing attached to the motor housing adjacent the drive end of the rotating drive shaft and loosely journaling the drive end of the drive shaft during assembly and test operations performed on the motor prior to attaching the drive end of the motor drive shaft to the drive end of the stub shaft.  
 
     
     
         9 . The pump apparatus of  claim 8  further including a compliant drive coupling connecting the drive end of the motor rotating drive shaft to the driven end of the stub shaft, for accommodating misalignment between the drive and stub shafts.  
     
     
         10 . The pump apparatus of  claim 9  wherein: 
 the drive end of the motor rotating drive shaft includes a reduced diameter cylindrical pilot extending thereform along the drive shaft axis, and a hex drive segment extending along the drive shaft axis from the cylindrical pilot; and  
 the driven end of the stub shaft includes a cylindrical pilot bore extending into the stub shaft along the axis of the stub shaft, and a hex socket extending into the stub shaft along the axis of the stub shaft from the pilot bore, the pilot bore and hex socket receiving the cylindrical pilot and hex drive segment of the rotating drive shaft of the motor.  
 
     
     
         11 . The pump apparatus of  claim 10  wherein the cylindrical pilot and pilot bore are sized for providing a tight circumferential fit between one another.  
     
     
         12 . The pump apparatus of  claim 9  wherein: 
 the drive and stub shafts each define a diameter at the drive and driven ends respectively thereof:  
 the compliant coupling includes a quill shaft having a cylindrical central pilot segment with a diameter less that the respective diameters of the drive and driven ends of the drive and stub shafts, the quill shaft also having a hex drive segment extending from either end of the cylindrical central pilot segment;  
 the drive end of the motor drive shaft includes a cylindrical pilot bore extending into the drive shaft along the axis of the drive shaft, and a hex socket extending into the drive shaft along the axis of the drive shaft from the pilot bore;  
 the driven end of the stub shaft includes a cylindrical pilot bore extending into the stub shaft along the axis of the stub shaft, and a hex socket extending into the stub shaft along the axis of the stub shaft from the pilot bore; and  
 the pilot bores and hex sockets in the drive and stub shafts are adapted for receiving the cylindrical pilot and hex drive segments of the quill shaft.  
 
     
     
         13 . The pump apparatus of  claim 12  wherein: 
 the drive end of the drive shaft further includes a spring pocket extending into the drive shaft along the axis of the drive shaft; and  
 the compliant coupling further includes a compression spring disposed in the spring pocket between the quill shaft and the spring pocket for urging the quill shaft to move along the drive shaft axis toward the stub shaft.  
 
     
     
         14 . The pump apparatus of  claim 9  further including at least one pump module defining a cylinder bore and a reciprocating axis extending through the cylinder bore from a first to a second axial end of the module, and having a piston in the cylinder bore for sliding motion along the reciprocating axis, the piston having an exposed end thereof extending from the second end of the module and connected to a drive mechanism.  
     
     
         15 . The pump apparatus of  claim 14  wherein the drive apparatus includes a return clip for attaching the exposed end of the piston to the eccentric.  
     
     
         16 . The pump apparatus of  claim 14  wherein the pump module includes a return spring for urging the exposed end of the piston into contact with outer race of the needle bearing.  
     
     
         17 . A pump drive apparatus for a installation in a pump housing and imparting reciprocating motion to a piston operatively installed in the housing, the pump drive apparatus comprising: 
 a stub shaft having an eccentric between a driven end and an end of the stub shaft opposite the driven end, the stub shaft journalled for self-supported rotation about a stub shaft axis by a first and a second rotating bearing disposed on opposite axial sides of the eccentric, the driven end of the stub-shaft adapted for operative connection to a rotating drive shaft to be rotated thereby, and the eccentric adapted for operative connection to the piston for imparting reciprocating motion to the piston; and    a motor including a motor housing for attachment of the motor to the pump housing, a rotating drive shaft having an anti-drive end within the motor housing and a drive end connected to the driven end of the stub shaft, a rotating drive shaft bearing attached to the motor housing for journaling the anti-drive end of the rotating drive shaft and having a spherical outer surface thereof operatively connected to the motor housing for allowing the rotating shaft to nutate about the axis of the rotating drive shaft.    
     
     
         18 . The pump drive apparatus of  claim 17  further comprising a bushing attached to the motor housing adjacent the drive end of the rotating drive shaft and loosely journaling the drive end of the drive shaft during assembly and test operations performed on the motor prior to attaching the drive end of the motor drive shaft to the drive end of the stub shaft.  
     
     
         19 . A pump drive apparatus for installation into a pump housing and imparting reciprocating motion to a piston operatively installed in the housing, the pump drive apparatus comprising: 
 a stub shaft having an eccentric between a driven end and an end of the stub shaft opposite the driven end, the stub shaft journalled for self-supported rotation about a stub shaft axis by a first and a second rotating bearing disposed on opposite axial sides of the eccentric, the driven end of the stub-shaft adapted for operative connection to a rotating drive shaft to be rotated thereby, and the eccentric adapted for operative connection to the piston for imparting reciprocating motion to the piston; and    a pair of thrust bearings disposed on the stub shaft adjacent the eccentric at opposite axial ends thereof between the eccentric and first and second rotating bearings;    at least one of the thrust bearings including a counterweight for balancing the pump drive apparatus.    
     
     
         20 . The pump drive apparatus of  claim 19  further comprising a motor having a rotating drive shaft attached to the driven end of the stub shaft, the motor not including any counterweights for balancing any part of the pump drive apparatus other than the motor itself.