Hydrostatic Axial Piston Machine

Abstract

A hydrostatic axial piston machine defines an adjustable displacement volume and includes a housing, a cylinder drum, a plurality of working pistons, a pivot cradle, and a plain bearing. The working pistons are received in the cylinder drum so as to be axially displaceable, and are supported on a sliding surface of the pivot cradle. The pivot cradle is configured to adjust the displacement volume, and is pivotably mounted on the plain bearing. The plain bearing is fixed with respect to the housing. The hydrostatic axial piston machine is configured to form at least one first hydrostatic relief pressure field between the plain bearing and the pivot cradle.

what is claimed is: 
     
         1 . A hydrostatic axial piston machine, defining an adjustable displacement volume, and comprising:
 a housing;   a cylinder drum;   a plain bearing fixed to the housing; and   a pivot cradle that is pivotably mounted on the plain bearing to enable formation of at least one first hydrostatic relief pressure field between the plain bearing and the pivot cradle, the pivot cradle defining a sliding surface and being configured to adjust the displacement volume;   a plurality of working pistons received in the cylinder drum so as to be axially displaceable, and supported on the sliding surface of the pivot cradle; and   a first pressure medium source;   the hydrostatic axial piston machine further defining a first pressure medium flow path from the first pressure medium source to the first hydrostatic relief pressure field, the first pressure medium flow path including an adjustable throughflow cross section.   
     
     
         2 . The hydrostatic axial piston machine of  claim 1 , further comprising:
 a second pressure medium source, wherein:
 the mounting of the pivot cradle on the plain bearing further enables formation of a second hydrostatic pressure relief field between the plain bearing and the pivot cradle; and 
 the hydrostatic axial piston machine further defines a second pressure medium flow path from the second pressure medium source to the second hydrostatic relief pressure field, the second pressure medium flow path including a second adjustable throughflow cross section. 
   
     
     
         3 . The hydrostatic axial piston machine of  claim 1 , further comprising:
 an adjustment device that includes a hydraulic actuating cylinder configured to adjust the displacement volume;   wherein the hydraulic actuating cylinder defines an actuating pressure chamber that enables formation of the first pressure medium source.   
     
     
         4 . The hydrostatic axial piston machine of  claim 3 , wherein:
 the adjustment device further includes a hydraulic restoring cylinder configured to restore the displacement volume; and   the hydraulic restoring cylinder defines a restoring pressure chamber that enables formation of the second pressure medium source.   
     
     
         5 . The hydrostatic axial piston machine of  claim 1 , wherein:
 the working pistons delimit a plurality of working chambers in the cylinder drum; and   the first pressure medium source includes a pressure medium connection to a subset of the plurality of working chambers in the cylinder drum.   
     
     
         6 . The hydrostatic axial piston machine of  claim 2 , wherein the hydrostatic axial piston machine is configured such that an adjustment of at least one of the first adjustable throughflow cross section and the second adjustable throughflow cross section is coupled to a change in the displacement volume. 
     
     
         7 . The hydrostatic axial piston machine of  claim 3 , wherein:
 the working pistons delimit at least one working chamber in the cylinder drum; and   the first pressure medium flow path extends through the pivot cradle from at least one of the at least one working chamber and the actuating pressure chamber to the first hydrostatic relief pressure field.   
     
     
         8 . The hydrostatic axial piston machine of  claim 1 , wherein:
 the sliding surface of the pivot cradle and at least one of the working pistons together delimit the first adjustable throughflow cross section;   at least one working piston includes a sliding pad, and the sliding surface of the pivot cradle and the sliding pad together delimit the first adjustable throughflow cross section; or   at least one working piston includes a sliding pad, and the at least one working piston and the sliding pad together delimit the first adjustable throughflow cross section.   
     
     
         9 . The hydrostatic axial piston machine of  claim 1 , further comprising at least one of:
 a first throttle device that forms the first adjustable throughflow cross section; and   a second throttle device that forms the second adjustable throughflow cross section.   
     
     
         10 . The hydrostatic axial piston machine of  claim 9 , wherein at least one of the first throttle device and that second throttle device respectively includes a controllable valve or a controllable aperture. 
     
     
         11 . The hydrostatic axial piston machine of  claim 1 , wherein at least one of:
 the plain bearing defines a first bearing surface that includes at least one first relief pressure pocket, the at least one first relief pressure pocket delimiting the first hydrostatic relief pressure field; and   the pivot cradle defines a second bearing surface that faces toward the plain bearing and that includes at least one second relief pressure pocket, the at least one second relief pressure pocket delimiting the first hydrostatic relief pressure field.   
     
     
         12 . The hydrostatic axial piston machine of  claim 11 , wherein in a neutral position of the pivot cradle:
 the displacement volume is zero; and   the first relief pressure pocket overlaps the second relief pressure pocket, at least in sections.   
     
     
         13 . The hydrostatic axial piston machine of  claim 11 , wherein:
 the pivot cradle is configured to pivot about a pivot axis that lies on a neutral plane of the pivot cradle;   the second bearing surface of the pivot cradle extends substantially symmetrically relative to the neutral plane; and   the second relief pressure pocket extends asymmetrically relative to the neutral plane.   
     
     
         14 . The hydrostatic axial piston machine of  claim 1 , wherein at least one of the plain bearing and the pivot cradle defines a plurality of relief pressure pockets spaced apart from each other along a pivoting direction. 
     
     
         15 . The hydrostatic axial piston machine of  claim 14 , wherein the first adjustable throughflow cross section is configured to supply at least one of the plurality of relief pressure pockets with pressure medium. 
     
     
         16 . The hydrostatic axial piston machine of  claim 6 , wherein the hydrostatic axial piston machine is configured such that an adjustment of at least one of the first adjustable throughflow cross section and the second adjustable throughflow cross section is coupled to a change in a pivot angle of the pivot cradle.