Fluid Pump With Shim And Related Methods Of Manufacture

Abstract

A fluid pump includes a gear housing with a pocket wall and a base. The pocket wall and the base define a pocket that projects into the gear housing from a pocket surface. The fluid pump also includes a first gear rotatably positioned in the pocket. The first gear is spaced from the pocket surface by a first gap. The fluid pump also includes a second gear rotatably positioned in the pocket that engages the first gear. The second gear is spaced from the pocket surface by a second gap. The fluid pump also includes a selected shim that is selected from a plurality of shims in a shim set. The selected shim has a thickness that results in a desired clearance between the selected shim and the first face or the second face.

What is claimed is: 
     
         1 . A fluid pump comprising:
 a gear housing including a pocket wall and a base, the pocket wall and the base defining a pocket that projects into the gear housing from a pocket surface;   a first gear rotatably positioned in the pocket, the first gear including a first face that is spaced from the pocket surface by a first gap;   a second gear rotatably positioned in the pocket and engaging the first gear, the second gear including a second face that is spaced from the pocket surface by a second gap; and   a selected shim positioned in the pocket over the first gear and the second gear, wherein the selected shim is selected from a plurality of shims in a shim set by comparing thicknesses of the shims in the plurality of shims to the first gap or the second gap, the selected shim having a thickness that results in a desired clearance between the selected shim and the first face or the second face.   
     
     
         2 . The fluid pump of  claim 1  wherein the desired clearance is a minimum clearance. 
     
     
         3 . The fluid plump of  claim 1  wherein the pocket wall includes two rounded portions to define a pocket with a first circular depression and a second circular depression, the first circular depression configured to receive the first gear and the second circular depression configured to receive the second gear. 
     
     
         4 . The fluid pump of  claim 1  further comprising a gear guide positioned in the pocket, the gear guide including a first post projecting upward in the pocket toward the pocket surface and a second post projecting upward in the pocket toward the pocket surface, the first post configured to receive the first gear and the second post configured to receive the second gear. 
     
     
         5 . The fluid pump of  claim 3  wherein the selected shim includes a first ring and a second ring, the first ring positioned over the first gear in the first circular depression and the second ring positioned over the second gear in the second circular depression. 
     
     
         6 . The fluid pump of  claim 1  further comprising a cover plate removably attached to the gear housing adjacent to the pocket surface and covering the pocket. 
     
     
         7 . The fluid pump of  claim 1  wherein, when the first gap is greater than the second gap, the selected shim is selected by comparing the thickness of the shims in the plurality of shims to the second gap. 
     
     
         8 . The fluid pump of  claim 1  wherein the plurality of shims includes at least five shims having different thicknesses. 
     
     
         9 . The fluid pump of  claim 8  wherein the thicknesses of the plurality of shims vary from 0.5 mm to 1.5 mm. 
     
     
         10 . The fluid pump of  claim 1  wherein the selected shim is selected from the plurality of shims after the first gear and the second gear are installed in the pocket and the first gap and the second gap are measured. 
     
     
         11 . A method of manufacturing a fluid pump comprising:
 inserting a first gear over a post in a pocket of a gear housing such that a face of the first gear is oriented toward a pocket surface of the gear housing and the first gear is configured to rotate around a center axis of the post;   measuring a height of a first gap between the face of the first gear and the pocket surface of the gear housing wherein the height of the first gap is measured in a direction parallel to the center axis;   comparing the height of the first gap to thicknesses of shims in a shim set, the shim set comprising a plurality of shims with varying thicknesses;   choosing a selected shim from the shim set wherein the thickness of the selected shim results in a desired clearance between the first gear and the selected shim; and   inserting the selected shim in the pocket over the first gear.   
     
     
         12 . The method of  claim 11  wherein the thickness of the selected shim is closest to and less than the height of the gap. 
     
     
         13 . The method of  claim 11  further comprising:
 inserting a second gear over a second post in the pocket of the gear housing such that a face of the second gear is oriented toward the pocket surface of the gear housing; 
 measuring a height of a second gap between the face of the second gear and the pocket surface of the gear housing wherein the height of the second gap is measured in a direction parallel to the center axis; 
 comparing the height of the second gap to the height of the first gap to determine if the height of the second gap is less than the height of the first gap; and 
 if the height of the second gap is less than the height of the first gap, comparing the height of the second gap to the thicknesses of the shims in the shim set; and 
 choosing the selected shim from the shim set to obtain the desired clearance between the second gear and the selected shim. 
 
     
     
         14 . The method of  claim 11  further comprising inserting a gear guide with the post into the pocket of the gear housing such that the post projects away from a base of the pocket toward the pocket surface and is configured to receive the first gear thereon. 
     
     
         15 . The method of  claim 11  wherein the shim set includes at least five shims having different thicknesses. 
     
     
         16 . The method of  claim 11  further comprising, securing a cover plate to the gear housing over the pocket, the cover plate configured to retain the first gear and the selected shim in the pocket. 
     
     
         17 . The method of  claim 11  wherein the desired clearance is a minimum clearance. 
     
     
         18 . The method of  claim 11  wherein, when the selected shim is inserted into the pocket of the gear housing, the selected shim minimizes unwanted leakage of fluid from the pocket. 
     
     
         19 . A fluid pump comprising:
 a gear housing including a pocket wall and a base, the pocket wall and the base defining a pocket that projects into the gear housing from a pocket surface;   a cover plate secured to the gear housing, the cover plate including a pocket side oriented toward the gear housing and over the pocket;   a first gear rotatably positioned in the pocket, the first gear including a first face oriented toward the pocket side of the cover plate, wherein the first face is spaced from the pocket side by a first gap;   a second gear rotatably positioned in the pocket and engaging the first gear, the second gear including a second face that is oriented toward the pocket side of the cover plate, wherein the second face is spaced from the pocket side by a second gap; and   a selected shim positioned in the pocket over the first gear and the second gear, wherein the selected shim is selected from a plurality of shims in a shim set by comparing thicknesses of the shims in the plurality of shims to the first gap or the second gap, the selected shim having a thickness that results in a desired clearance between the selected shim and the first face or the second face.   
     
     
         20 . The fluid pump of  claim 19  wherein the pocket surface of the gear housing and at least a portion of the pocket side of the cover plate are separated from one another over the pocket.