Sliding Bearing and Pump Device Using the Same

Abstract

In a sliding bearing, load carrying capacity and bearing rigidity is increased without increasing a size of the bearing and the pressure of the fluid. The sliding bearing comprises a cylindrical-shaped sleeve supporting a rotatable shaft via fluid, and hydrostatic pressure pockets provided in the inner periphery of the sleeve. The hydrostatic pressure pockets constitute a plurality of rows of circumferentially disposed hydrostatic pressure pockets via orifices. At least one of the hydrostatic pressure pocket rows is arranged adjacently to each of both end portions of the inner periphery of the sleeve. And a circular cylindrical inner peripheral surface region without the hydrostatic pressure pockets is provided at a center portion of the sleeve. A width of the circular cylindrical inner peripheral surface region provided in the axial direction of the shaft is made wider than a sum of widths of the hydrostatic pressure pocket rows.

What is claimed is: 
     
         1 . A sliding bearing comprising a substantially circular cylindrical-shaped sleeve slidingly supporting a rotatable shaft via fluid in an inner periphery thereof, hydrostatic pressure supplying passages penetrating through the sleeve and supplying high pressure fluid into the sleeve inner periphery from an external pressure source, and hydrostatic pressure pockets provided in the inner periphery of the sleeve and having radially recessed shapes, the hydrostatic pressure supplying passages being opened in the hydrostatic pressure pockets,
 wherein the hydrostatic pressure pockets constitute a plurality of rows of circumferentially disposed hydrostatic pressure pockets, at least one of the hydrostatic pressure pocket rows being arranged adjacently to each of both end portions of the inner periphery of the sleeve in an axial direction of the shaft, and a circular cylindrical inner peripheral surface region in which the hydrostatic pressure pockets are not present is provided at a center portion of the sleeve so as to be interposed between the hydrostatic pressure pocket rows.   
     
     
         2 . The sliding bearing according to  claim 1 , wherein a width of the circular cylindrical inner peripheral surface region without the hydrostatic pressure pockets provided in the axial direction of the shaft is made wider than a sum of widths of the hydrostatic pressure pocket rows provided in the axial direction of the shaft. 
     
     
         3 . The sliding bearing according to  claim 1 , wherein hydrostatic pressure supplying passages communicating with hydrostatic pressure pockets belonging to the same hydrostatic pressure pocket row and hydrostatic pressure supplying passages communicating with hydrostatic pressure pockets belonging to a different hydrostatic pressure pocket row are independently communicated with the pressure source supplying the high pressure fluid. 
     
     
         4 . The sliding bearing according to  claim 1 , wherein an arrangement-angle range of hydrostatic pressure pockets which extends in a circumferential direction has a shape that is superposed on an arrangement-angle range of adjacent hydrostatic pressure pockets. 
     
     
         5 . The sliding bearing according to  claim 1 , wherein an arrangement-angle range of hydrostatic pressure pockets which extends in a circumferential direction is located so as to be superposed on an arrangement-angle range of adjacent hydrostatic pressure pockets. 
     
     
         6 . The sliding bearing according to  claim 1 , wherein each of the hydrostatic pressure pockets has a shape in which an outer side of the hydrostatic pressure pocket that is adjacent to an end portion of the sleeve extends to an upstream side relative to a rotational direction of the shaft as compared to an inner side of the hydrostatic pressure pocket that is remote from the end portion of the sleeve and the inner side of the hydrostatic pressure pocket that is remote from the end of the sleeve extends to a downstream side relative to the rotational direction of the shaft as compared to the outer side of the hydrostatic pressure pocket that is adjacent to the end portion of the sleeve. 
     
     
         7 . The sliding bearing according to  claim 1 , wherein a region of the sleeve inner periphery that has no hydrostatic pressure pockets is formed with grooves in which the hydrostatic pressure supplying passages are not opened. 
     
     
         8 . A pump device comprising an impeller arranged at a midway of a fluid passage and transferring fluid according to rotational movement thereof, a shaft connected to an rotation power source and rotation-driving the impeller, a substantially circular cylindrical-shape sleeve slidingly supporting an outer peripheral surface of the shaft via the fluid, hydrostatic pressure supplying passages penetrating through the sleeve and supplying high pressure fluid into an inner periphery of the sleeve from an outlet side of the fluid passage, and a sliding bearing having hydrostatic pressure pockets which are provided in the inner periphery of the sleeve and have radially recessed shapes, the hydrostatic pressure supplying passages being opened in the hydrostatic pressure pockets,
 wherein the hydrostatic pressure pockets constitute a plurality of rows of circumferentially disposed hydrostatic pressure pockets, at least one of the hydrostatic pressure pocket rows being arranged adjacently to each of both end portions of the inner periphery of the sleeve in an axial direction of the shaft, and a circular cylindrical inner peripheral surface region in which the hydrostatic pressure pockets are not present is provided at a center portion of the sleeve so as to be interposed between the hydrostatic pressure pocket rows.   
     
     
         9 . The pump device according to  claim 8 , wherein a width of the circular cylindrical inner peripheral surface region which is provided in an axial direction of the shaft is made wider than a sum of widths of the hydrostatic pressure pocket rows which is provided in the axial direction of the shaft. 
     
     
         10 . The pump device according to  claim 8 , wherein hydrostatic pressure supplying passages communicating with hydrostatic pressure pockets belonging to a hydrostatic pressure pocket row and hydrostatic pressure supplying passages communicating with hydrostatic pressure pockets belonging to a different hydrostatic pressure pocket row are independently communicated with the outlet side of the fluid passage. 
     
     
         11 . The pump device according to  claim 8 , wherein the fluid that flows through the fluid passage is fluid metal.