Cartridge vane pump having enhanced cold start performance

Abstract

A cartridge vane pump for a motor vehicle power steering system exhibits improved cold start performance. The pump includes a plurality of radially disposed vanes which are received within a rotor which is rotatably supported within a cylindrical cam ring defining two diametrically opposed pumping lobes. An inlet (upper) section and an outlet (lower) section engage the ends of the cam ring and define suitable passageways which provide fluid into and out of the pumping lobes. Under vane porting in the inlet section provides high pressure fluid to the inner edges of the vanes received within the rotor as they traverse the intake portions of the pumping lobes urging the vanes into contact with the cam ring surface.

We claim:  
     
         1 . A cartridge vane pump comprising, in combination, 
 a housing including a first end section, a second end section and a middle cam ring section disposed between said end sections and defining a pump chamber, said pump chamber defining intake regions of increasing diameter,    a rotor defining a plurality of axially and radially extending slots having inner ends and vanes disposed in respective said slots,    a shaft extending into said chamber for driving said rotor, and    one of said end sections defining arcuate passageways communicating with said inner ends of said vane slots and aligned with said intake regions of said pump chamber in fluid communication with a high pressure outlet of said pump.    
     
     
         2 . The cartridge vane pump of  claim 1  wherein said rotor includes a splined opening and said shaft includes splines disposed in said splined opening.  
     
     
         3 . The cartridge vane pump of  claim 1  further including a pair of alignment pins extending from said first end section, through said cam ring section and into said second end section.  
     
     
         4 . The cartridge vane pump of  claim 1  wherein said pump chamber of said cam ring section defines two lobes and said rotor defines ten slots.  
     
     
         5 . The cartridge vane pump of  claim 1  wherein said first end section defines inlet passageways and said second end section defines outlet passageways.  
     
     
         6 . The cartridge vane pump of  claim 1  wherein said shaft is received within passageways defined by both end sections.  
     
     
         7 . The cartridge vane pump of  claim 1  wherein both of said end sections define arcuate passageways aligned with said intake regions of said pump chamber and communicate with said inner ends of said vane slots.  
     
     
         8 . A cartridge vane pump comprising, in combination, 
 a housing including a first end section, a second end section and a middle cam ring section disposed between said end sections and defining a pump chamber, said pump chamber defining intake regions of increasing diameter,    a rotor defining a plurality of axially and radially extending slots having inner ends and vanes disposed in respective said slots,    a shaft extending through one of said end sections and into said chamber for driving said rotor, and    one of said end sections defining arcuate passageways communicating with said inner ends of said vane slots and angularly aligned with said intake regions of said pump chamber in fluid communication with high pressure outlets of said pump whereby fluid under pressure is provided to inner edges of said vanes.    
     
     
         9 . The cartridge vane pump of  claim 8  wherein said rotor includes a splined opening and said shaft includes splines disposed in said splined opening.  
     
     
         10 . The cartridge vane pump of  claim 8  further including a pair of alignment pins extending from said first end section, through said cam ring section and into said second end section  
     
     
         11 . The cartridge vane pump of  claim 8  wherein said pump chamber of said cam ring section defines two lobes and said rotor defines ten slots.  
     
     
         12 . The cartridge vane pump of  claim 8  wherein said first end section defines inlet passageways and said second end section defines outlet passageways.  
     
     
         13 . The cartridge vane pump of  claim 8  wherein both of said end sections define arcuate passageways aligned with said intake regions of said pump chamber and communicate with said inner ends of said vane slots.