摘要 |
A piston-type fluid displacement apparatus includes several pistons, each of which is slidably disposed within one of several cylinder bores. A plating layer, which includes a self-lubricating material, is coated on a peripheral surface of each piston. At least one annular groove is formed on a periphery surface of each piston, and, at least one piston ring is disposed within the annular groove of each piston for sealing a gap between the piston and the cylinder bore. Thereby, the piston-type fluid displacement apparatus may be simply manufactured at a reduced assembly cost while simultaneously prolonging the life of the piston rings and while reducing or eliminating a decrease in compression efficiency during the operating life of the piston-type fluid displacement apparatus.
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