Gear Pump

Abstract

In a gear pump, a gear chamber is defined in a housing hole of a housing. A pair of gears is housed in the gear chamber. The gears are rotatably supported at support holes of a pair of side plates via support shafts. As viewed in an axial direction of the support shafts during rotation of the gears, addendum circles of the gears displaced under a differential pressure between a low-pressure chamber and a high-pressure chamber form first contact points with respect to an inner peripheral surface that defines a housing hole. As viewed in the axial direction of the support shafts during rotation of the gears, the first contact points are covered with the side plates displaced under the differential pressure.

What is claimed is: 
     
         1 . A gear pump comprising:
 a housing having a housing hole;   a pair of side plates disposed in the housing hole so as to face each other such that a gear chamber is defined between the side plates, each of the side plates having a pair of support holes; and   a pair of gears disposed in the gear chamber so as to be meshed with each other, the gears being rotatably supported by the side plates via support shafts inserted into the support holes, wherein   when the gear pump is viewed in an axial direction of each of the support shafts during rotation of the gears, a low-pressure chamber and a high-pressure chamber that is higher in pressure than the low-pressure chamber are defined inside the gear chamber, with a meshing position interposed between the low-pressure chamber and the high-pressure chamber, the meshing position being a position at which the gears are meshed with each other,   an addendum circle of each of the gears that are displaced under a differential pressure between the low-pressure chamber and the high-pressure chamber forms a first contact point with respect to an inner peripheral surface that defines the housing hole in which the gears are housed, and   the first contact point is covered with the side plates that are displaced under the differential pressure.   
     
     
         2 . The gear pump according to  claim 1 , wherein
 the housing hole includes a pair of cylindrical hole sections in which the gears are respectively housed,   each of the side plates includes a pair of disc portions respectively fitted in the cylindrical hole sections, and   a first distance and a second distance are equal to each other, the first distance being a distance between central axes of the cylindrical hole sections of the housing hole, and the second distance being a distance between central axes of the disc portions of each of the side plates.