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US 5,117,742 AGranted
Piston of composite material with C-shaped ring groove
AssigneeIwata Air Compressor Mfg. Co., Ltd.
InventorToshio Iida
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AssigneeIwata Air Compressor Mfg. Co., Ltd.
InventorToshio Iida
Estimating the term…
The present invention relates to an oilless reciprocating compressor and expansion apparatus each comprising a piston body to which a piston ring made of a self-lubricating material is fitted and a metal cylinder, and in the first invention and the second invention a self-lubricating material can be formed on the piston itself or on the circumferential surface side thereof without influencing adversely the durability of the piston itself by the compression heat at the piston top, and in the third invention a ring groove formed into the shape of the letter C whose ends are spaced a little is provided in the piston circumferential surface at least whose surface side is made of a self-lubricating material, and said ring groove is positioned on the side thrust line orthogonal to the piston pin, so that the compression efficiency is improved.
An oilless multi-stage reciprocating compressor comprising a piston to which piston rings made of a self-lubricating material are fitted at the lower side and the higher side, wherein at least the sliding surfaces of the piston and/or the cylinder on the lower side and the higher side are made of a self-lubricating material, ring grooves formed in the circumferential surface of said piston are formed into the shape of the letter C whose ends are spaced a little, said piston is assembled in such a way that said spacing parts are positioned respectively at the side thrust section in firm contact with the cylinder in the piston ascending step on the lower side, and at the side thrust sections in the piston ascending step and the piston descending step on the higher side, and the combination of the spacing parts and the piston ring allows the corresponding cylinders to be sealed airtightly.
In an oilless reciprocating compressor/expansion apparatus comprising a piston body arranged in a cylinder in sliding contact therewith and having a substantially annular ring groove, and a split piston ring made of a self-lubricating resilient material disposed in said ring groove, the improvement comprising at least the portions of said piston body in sliding contact with said cylinder being formed of a self-lubricating composite material containing a thermosetting condensed polycyclic polynuclear aromatic resin and a heat-resistant slidability-increasing material, and said ring groove being substantially C-shaped with a partition wall formed in the remaining circumference, said partition wall filling a gap between the ends of said split piston ring.
Dependencies are inferred from the claim text.