Piston assembly having abradable coating

In a pump, compressor or heat engine, an oil bathed piston and cylinder assembly, carrying an oil film along the cylinder wall, said oil film having a viscosity in the range of 5 to 200 cp, comprising:

• (a) a piston body having a central axis of movement and at least one land in close fitting relationship with said cylinder wall;
• (b) a plurality of grooves in said piston body facing the cylinder wall, said grooves being spaced along or around said axis of the piston body;
• (c) an abradable solid film lubricant coating tenaciously adhered to at least said land effective to create substantially zero clearance between the oil film of said cylinder wall and said piston body, said coating containing heat conductors to conduct heat from said land, said coating consisting of copper flakes having a particle size in the range of 5 to 25 microns with an aspect ratio of 1-20;
• (d) compression sealing elements carried in said grooves to dynamically and adjustably maintain contact between the piston body and cylinder wall;
• and
• (e) a solid film lubricant coating said grooves and sealing elements.

In a pump, compressor or heat engine, an oil bathed piston and cylinder assembly, said piston having a working surface for compressing fluids, said assembly carrying an oil film along a cylinder wall, said oil film having a viscosity in the range of 5 to 200 cp, comprising:

• (a) a piston body having a central axis of movement and at least one land in close fitting relationship with said cylinder wall, said land being adjacent said working surface, said piston body also having an interior receiving a heat conducting fluid therealong to promote a first heat sink effect;
• (b) a plurality of grooves in said piston body facing the cylinder wall, said grooves being spaced along or around said axis of the piston body;
• (c) an abradable solid film lubricant coating tenaciously adhered to at least said land effective to create substantially zero clearance between the oil film of said cylinder wall and said piston body, said coating containing particles to establish a heat sink effect to said cylinder wall;
• (d) compression sealing elements carried in said grooves to dynamically and adjustably maintain contact between the piston body and oil film of said cylinder wall;
• and
• (e) a solid film lubricant coating only said grooves and sealing elements.