Efficiency Spur Gear Set Housing

Abstract

A hydraulic pump housing comprises passages formed in an inner wall separating the gear cavity and the pump cavity to allow for the movement of fluid into and out of the gear cavity, thereby alleviating some of the power loss caused by churning lubricating oil. The hydraulic pump may comprise spaces integrally formed in axially opposing surfaces of the gear cavity walls adjacent the area where the gears mesh to enable the churning oil to expand and flow around the gears.

We claim: 
     
         1 . A housing for a spur gear set of a hydraulic pump, comprising:
 a first member, and a second member substantially coextensive with the first member, the first and second members being affixed together to define a gear cavity;   the first member comprising an inner wall forming a rear inner surface of the gear cavity, and a perimeter wall forming a top inner surface, a bottom inner surface and side inner surfaces of the gear cavity;   the second member forming a front inner surface of the gear cavity;   a drive gear and a drive gear submerged in fluid, the drive gear and driven gear located in the gear cavity; and   one or more passages formed in the inner wall to allow movement of the fluid into and out of the gear cavity.   
     
     
         2 . The housing of  claim 1  wherein the one or more passages comprises two arcuate shaped side passages located near the side inner surfaces of the perimeter wall, each side passage forming an arc of less than ninety degrees. 
     
     
         3 . The housing of  claim 2  wherein the side passages are equidistant from the top inner surface and the bottom inner surface of the perimeter wall. 
     
     
         4 . The housing of  claim 1  wherein the first member comprises integrally formed top and bottom gear shrouds, the top gear shroud extending downward from the top inner surface of the perimeter wall and having downwardly converging curved sides that meet along a substantially linear apex located equidistant the gears, the bottom gear shroud extending upward from the bottom inner surface of the perimeter wall and having upwardly converging curved sides that meet along a substantially linear apex located equidistant the gears. 
     
     
         5 . The housing of  claim 1 , wherein the first member is a housing body, and the second member is a flange. 
     
     
         6 . A hydraulic pump, comprising:
 a housing for a spur gear set comprising a first member and a second member affixed together to define a gear cavity within which are located a drive gear and a driven gear submerged in fluid;   the gear cavity having an area where the gears mesh;   the first member comprising an inner wall forming a substantially planar rear inner surface of the gear cavity;   the second member forming a substantially planar front inner surface of the gear cavity;   one or more expansions integrally formed in the rear inner surface of the inner wall adjacent to the area where the gears mesh, the one or more expansions being a space through which the fluid flows around the gears from one side of the area where the gears mesh to the other side of the area where the gears mesh; and   wherein each of the one or more expansions is defined by a first outwardly sloping wall located adjacent an area of highest oil pressure within the gear cavity and a second outwardly sloping wall located adjacent an area of lowest oil pressure within the gear cavity.   
     
     
         7 . The hydraulic pump of  claim 6 , wherein the one or more expansions are a depression. 
     
     
         8 . The hydraulic pump of  claim 6 , wherein the one or more expansions are tunnels, each tunnel having an inlet opening adjacent to the area where the gears begin to mesh and an outlet opening adjacent to the area where the gears begin to unmesh. 
     
     
         9 . The hydraulic pump of  claim 6 , wherein:
 the one or more expansions are defined by a first wall sloping outwardly away from the gears and a second wall sloping outwardly away from the gears, the first and second walls converging near the area of greatest engagement between where the drive gear and the driven gear mesh.   
     
     
         10 . The hydraulic pump of  claim 6 , wherein:
 the one or more expansions comprises a concave area formed in the inner wall.   
     
     
         11 . The hydraulic pump of  claim 6 , wherein:
 the one or more expansions comprise a first concave area formed in the inner wall, the first concave area being elongated in a direction defined by a line passing through an area of greatest gear engagement.   
     
     
         12 . The hydraulic pump of  claim 6 , wherein the first member is a housing body, and the second member is a flange. 
     
     
         13 . The hydraulic pump of  claim 6 , further comprising one or more passages formed in the inner wall to allow movement of the fluid into and out of the gear cavity. 
     
     
         14 . The hydraulic pump of  claim 13 , wherein the first member further comprises a perimeter wall forming a top inner surface, a bottom inner surface and side inner surfaces of the gear cavity, and wherein the one or more passages comprises two arcuate shaped side passages located near the side inner surfaces of the perimeter wall, each side passage forming an arc of less than ninety degrees. 
     
     
         15 . The hydraulic pump of  claim 14 , wherein the side passages are equidistant from the top inner surface and the bottom inner surface of the perimeter wall. 
     
     
         16 . The hydraulic pump of  claim 15 , wherein the first member comprises integrally formed top and bottom gear shrouds, the top gear shroud extending downward from the top inner surface of the perimeter wall and having downwardly converging curved sides that meet along a substantially linear apex located equidistant the gears, the bottom gear shroud extending upward from the bottom inner surface of the perimeter wall and having upwardly converging curved sides that meet along a substantially linear apex located equidistant the gears. 
     
     
         17 . The hydraulic pump of  claim 16 , wherein the first member is a housing body, and the second member is a flange. 
     
     
         18 . A hydraulic pump, comprising:
 a housing for a spur gear set comprising a first member and a second member affixed together to define a gear cavity within which are located a drive gear and a driven gear submerged in fluid;   the gear cavity having an area where the gears mesh;   the first member comprising an inner wall forming a substantially planar rear inner surface of the gear cavity;   the second member forming a substantially planar front inner surface of the gear cavity;   one or more expansions integrally formed in the rear inner surface of the inner wall adjacent to the area where the gears mesh, the one or more expansions first being a space through which the fluid flows around the gears from one side of the area where the gears mesh to the other side of the area where the gears mesh; and   wherein each of the one or more expansions comprise a first concave area formed in the inner wall, the first concave area being elongated in a direction defined by a line passing through an area of greatest gear engagement.   
     
     
         19 . The hydraulic pump of  claim 18 , wherein each of the one or more expansions are depressions. 
     
     
         20 . The hydraulic pump of  claim 18 , wherein each of the one or more expansions are tunnels, each tunnel having an inlet opening adjacent to the area where the gears begin to mesh and an outlet opening adjacent to the area where the gears begin to unmesh.