Axial sliding bearing and method of reducing power losses thereof

An axial piston machine comprising:

• a cylinder block adapted to be rotated about an axis of the axial piston machine;
• a plurality of cylindrical bores defined in the cylinder block and surrounding the axis;
• a plurality of pistons reciprocably disposed within the cylindrical bores;
• and
• a valve body having a fluid inlet through which a fluid enters the cylindrical bores and a fluid outlet through which the fluid leaves the cylindrical bores as the pistons reciprocate within the cylindrical bores, the fluid forming a fluid film within an interface between mating surfaces of the cylinder block and the valve body that face each other, the mating surface of the cylinder block having a sealing land and a bearing land, the machine configured such that the mating surfaces slidably move relative to each other in a first direction of motion while maintaining the interface therebetween and maintaining bearing and sealing functions thereat;
• wherein a surface profile comprising an oscillatory waveform located at least on the sealing land of the cylinder block and optionally also on a portion of the valve body that directly faces the sealing land of the cylinder block, the oscillatory waveform defining a circular path that is continuous in the first direction of motion, the oscillatory waveform having a peak-to-peak amplitude of less than one hundred micrometers, the oscillatory waveform producing a hydrodynamic sealing effect sufficient to provide a sealing function around the fluid inlet, the fluid outlet, and the cylindrical bores that limits fluid leakage from the fluid film within the interface as the mating surfaces slidably move relative to each other in the first direction of motion.

A method of reducing power losses of an axial piston machine having a cylinder block adapted to be rotated about an axis of the axial piston machine, a plurality of cylindrical bores defined in the cylinder block and surrounding the axis, a plurality of pistons reciprocably disposed within the cylindrical bores, and a valve body having a fluid inlet through which a fluid enters the cylindrical bores and a fluid outlet through which the fluid leaves the cylindrical bores as the pistons reciprocate within the cylindrical bores, the fluid forming a fluid film within an interface between mating surfaces of the cylinder block and the valve body that face each other, the mating surface of the cylinder block having a sealing land and a bearing land, the machine configured such that the mating surfaces slidably move relative to each other in a first direction of motion and function as bearing and sealing surfaces for the hydrostatic axial sliding bearing while maintaining the inter therebetween and maintaining bearing and sealing functions thereat, the machine comprising at least a first fluid opening in at least one of first and second axial sliding bearing surfaces through which a fluid flows to form the fluid film within the interface between the cylinder block and valve body, the method comprising:

• forming a surface profile comprising an oscillatory waveform on at least either on the sealing land of the cylinder block or on a portion of the valve body that directly faces the sealing land of the cylinder block that defines a circular path and is continuous in the first direction of motion, the oscillatory waveform having a peak-to-peak amplitude of less than one hundred micrometers, the oscillatory waveform producing a hydrodynamic sealing effect sufficient to provide a sealing function around the fluid inlet fluid film outlet, and the cylindrical bores that limits fluid leaking from the fluid film within the interface as the first and second axial sliding bearing surfaces slidably move relative to each other in the first direction of motion, the oscillatory waveform if the surface profile is formed to have a being a sinusoidal, a triangular, or a sawtooth waveform.