Bearing structure for gear in external gear pump

Abstract

A gear bearing structure for an external gear pump includes a driving gear and the driven gear accommodated rotatably in a pump body of the external gear pump, an inlet chamber formed on one side of a mesh portion of the driving gear and the driven gear, an outlet chamber formed on the other side of the mesh portion, a hollow cylindrical bushing for holding a rotational shaft of the driving gear or the driven gear with a lubricating liquid film formed between itself and the rotational shaft, and a ring plate spring disposed between the pump body and the bushing to urge the bushing so as to slidably contact with a side face of the one of the driving gear and the driven gear.

What is claimed is: 
     
         1 . A bearing structure of a gear for an external gear pump, the structure comprising:
 a driving gear and the driven gear that are accommodated rotatably in a pump body of the external gear pump;   an inlet chamber that is formed on one side of a mesh portion of the driving gear and the driven gear;   an outlet chamber that is formed on another side of the mesh portion;   a bushing that is hollow cylindrical, and holds a rotational shaft of one of the driving gear and the driven gear with a lubricating liquid film formed between itself and the rotational shaft; and   a ring plate spring that is disposed between the pump body and the bushing, and urges the bushing so as to slidably contact with a side face of the one of the driving gear and the driven gear.   
     
     
         2 . The bearing structure of a gear for an external gear pump according to  claim 1 , wherein the ring plate spring is a wave washer having a waving shape along a circumferential direction thereof. 
     
     
         3 . The bearing structure of a gear for an external gear pump according to  claim 1 , further comprising a flow passage for introducing fluid from the outlet chamber to a position where the ring plate spring is located. 
     
     
         4 . The bearing structure of a gear for an external gear pump according to  claim 2 , further comprising a flow passage for introducing fluid from the outlet chamber to a position where the ring plate spring is located.