Internal Leakage Control and Venting for ABS Unit

Abstract

A housing block for a hydraulic unit of a vehicle brake system that retaining a piston pump and an eccentric element that rotates the piston. A motor drives the eccentric element within an eccentric chamber. The block has a cylindrical cavity within a hydraulic leakage reservoir and a fluid leakage path that begins near a lower most portion of the eccentric element chamber and extends to a cylindrical cavity by way of a passage defined by an intersection of the eccentric chamber and cylindrical cavity. A pressure equalization path extends from the eccentric chamber upwardly to a point intermediate the housing block and motor enclosure and into the motor enclosure to a location that is substantially above the eccentric chamber. A seal intermediate the motor enclosure and housing block is formed as a closed curve of mastic material encircling the motor shaft, eccentric chamber, hydraulic leakage reservoir hydraulic fluid leakage path, and pressure equalization path.

1 . In the manufacture of a braking system hydraulic pump having a pump housing with a generally planar face, at least one pump piston reciprocably disposed within the housing, a pump actuating motor having a face joinable to the housing face and having a motor shaft with an eccentric near a free end thereof for drivingly coupling the motor shaft and at least one piston, and an eccentric cavity in the housing for receiving said eccentric, an improved process of providing a hydraulic fluid leakage reservoir in the housing, comprising: 
 creating a blind hole in said housing extending generally orthogonally from said housing face into the housing and intersecting the eccentric cavity within the housing; and    sealing the open bore end along the housing face byjoining the motor and housing faces.    
   
   
       2 . The process of  claim 1 , including the additional steps of forming a pressure differential vent in the motor face, and sealing the vent from the external environment.  
   
   
       3 . The process of  claim 2 , wherein the steps of sealing the open bore and sealing the vent are performed simultaneously by applying a mastic material to one of the motor face and housing face, and juxtaposing the housing and motor faces.  
   
   
       4 . The process of  claim 1 , wherein the step of sealing the open bore includes applying a viscous sealant material to one of the motor face and housing face, and juxtaposing the housing and motor faces.  
   
   
       5 . The process of  claim 1  wherein the eccentric cavity comprises a blind generally cylindrical bore extending inwardly from the housing face and an undercut region along a portion of the bore cylinder intermediate the ends thereof, the step of boring the blind hole in the housing including intersecting the eccentric cavity only in the undercut region.  
   
   
       6 . The process of  claim 1 , further including the steps of; 
 creating an additional blind hole in the housing extending generally orthogonally from said housing face into the housing and intersecting the eccentric cavity within the housing; and    sealing the open bore end and additional bore end along the housing face by applying a mastic material to one of the motor face and housing face, and joining the motor and housing faces.    
   
   
       7 . A hydraulic pump for a braking system, comprising: 
 a pump housing having a cavity for receiving a driving shaft and eccentric, and a pair of opposed pump piston cylinders spanning the cavity;    a pump driving motor and motor enclosure having a shaft rotatable about an axis with an eccentric member extending therefrom, the housing and motor enclosure being sealinglyjoinable along a common generally planar surface with the shaft axis extending generally orthogonal to the planar surface;    the pair of pump cylinders adapted to receive respective pistons reciprocable therein along a common axis generally orthogonal to the shaft axis in response to eccentric motion; and    a leakage fluid reservoir including a reservoir cylinder in fluid communication with the eccentric cavity for receiving leakage hydraulic fluid therefrom, the reservoir cylinder having an axis extending generally parallel to the shaft axis.    
   
   
       8 . The hydraulic pump of  claim 7 , wherein the eccentric cavity comprises a blind generally cylindrical bore extending inwardly from the planar surface, and an undercut region along a portion of the bore cylinder intermediate the ends thereof, the leakage fluid reservoir cylinder being in fluid communication with the eccentric cavity solely in the undercut region.  
   
   
       9 . The hydraulic pump of  claim 7 , wherein the housing and motor enclosure are sealingly joined along the common surface, and further including a pressure differential compensating vent providing an air path between the housing interior and the motor interior.  
   
   
       10 . The hydraulic pump of  claim 7 , wherein the leakage fluid reservoir includes a lowermost portion of the eccentric cavity and a second reservoir cylinder in fluid communication with the eccentric cavity for receiving leakage hydraulic fluid therefrom, the second reservoir cylinder having an axis extending generally parallel to the shaft axis.  
   
   
       11 . A hydraulic pump for a braking system, comprising: 
 a pump housing having a cavity for receiving a driving shaft and eccentric, and a pair of opposed pump piston cylinders spanning the cavity;    a pump driving motor and motor enclosure having a shaft rotatable about an axis with an eccentric member extending therefrom, the housing and motor enclosure being sealingly joinable along a common surface with the shaft axis extending generally in a horizontal direction into the eccentric cavity;    the pair of pump cylinders adapted to receive respective pistons reciprocable therein along a common axis generally orthogonal to the shaft axis in response to eccentric motion;    a leakage fluid reservoir including a reservoir cylinder in fluid communication with the eccentric cavity for receiving leakage hydraulic fluid therefrom; and    a pressure differential compensating vent positioned above the eccentric cavity for providing an air path between the housing interior and the motor enclosure interior.    
   
   
       12 . The hydraulic pump of  claim 11 , wherein the reservoir cylinder has an axis extending generally parallel to the shaft axis.  
   
   
       13 . The hydraulic pump of  claim 11 , wherein the eccentric cavity comprises a blind generally cylindrical bore extending inwardly from the common surface, and an undercut region along a portion of the bore cylinder intermediate the ends thereof, the leakage fluid reservoir cylinder being in fluid communication with the eccentric cavity solely in the undercut region.  
   
   
       14 . The hydraulic pump of  claim 13 , wherein the undercut region comprises a portion of a cylinder of diameter and axial extents both less than the respective diameter and axial extents of the bore cylinder.  
   
   
       15 . The hydraulic pump of  claim 13 , wherein the leakage fluid reservoir includes the undercut region of the eccentric cavity and a second reservoir cylinder in fluid communication with the eccentric cavity undercut region for receiving leakage hydraulic fluid therefrom, the second reservoir cylinder having an axis extending generally parallel to the shaft axis.  
   
   
       16 . A hydraulic unit of a vehicle brake system, comprising a housing block, at least one piston pump retained inside the housing block having a piston with an eccentric element that displaces the piston, an eccentric element chamber within the housing block in which said eccentric element is rotatable, a motor for driving said eccentric element, a motor enclosure, a hydraulic leakage reservoir comprising at least one generally cylindrical cavity in said housing block, a hydraulic fluid leakage path that begins near a lower most portion of the eccentric element chamber and extends to the at least one generally cylindrical cavity through a passage comprising an intersection of the eccentric element chamber and cylindrical cavity, and a pressure equalization path extending from the eccentric element chamber upwardly intermediate the housing block and motor enclosure and into the motor enclosure at a location substantially above the eccentric chamber.  
   
   
       17 . A hydraulic unit in accordance with  claim 16 , further comprising a seal intermediate the motor enclosure and housing block formed as a closed curve of mastic material encircling the motor shaft, eccentric chamber, hydraulic leakage reservoir, hydraulic fluid leakage path, and pressure equalization path.