Piston for Internal Combustion Engine and Piston Surface Treatment Method
AssigneeHitachi Automotive Systems, Ltd.
InventorMasato SASAKI
Life of this patent
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Abstract
A piston for an internal combustion engine includes a piston base material and a film of lubrication coating composition. The coating composition has an inner coating layer formed on a surface of the piston base material and an outer coating layer formed on a surface of the inner coating layer. Each of the inner coating layer and the outer coating layer contains at least one of a polyamide-imide resin, a polyimide resin and an epoxy resin as a binder. The inner coating layer contains 0 to 50 wt % of at least one of graphite and molybdenum disulfide as a solid lubricant, whereas the outer coating layer contains 50 to 95 wt % of at least one of graphite and molybdenum disulfide as a solid lubricant.
Claims7
A piston for an internal combustion engine, comprising:
- a skirt portion having an outer circumferential surface formed with a surface roughness for sliding contact with a cylinder wall of the engine,
- the skirt portion comprising:
- a piston base material;
- and
- a film of lubrication coating composition having an inner coating layer formed on a surface of the piston base material and an outer coating layer formed on a surface of the inner coating layer opposite the piston base material,
- wherein the outer coating layer is more susceptible to wear than the inner coating layer;
- and
- wherein the piston satisfies the following dimensional condition:
- t2≧a−5 where t2 (μm) is a thickness of the outer coating layer;
- and a is a height of the surface roughness before wearing of the coating composition.
A piston for an internal combustion engine, comprising:
- a skirt portion having an outer circumferential surface formed with a surface roughness for sliding contact with a cylinder wall of the engine,
- the skirt portion comprising:
- a piston base material;
- and
- a film of lubrication coating composition having an inner coating layer formed on a surface of the piston base material and an outer coating layer formed on a surface of the inner coating layer opposite the piston base material,
- wherein the inner coating layer and the outer coating layer contain the same binder resin;
- wherein the outer coating layer is more susceptible to wear than the inner coating layer;
- and
- wherein, during sliding contact of the piston skirt portion and the engine cylinder wall, the outer coating layer is worn in such a manner that the surface roughness is 5.5 mm or smaller.
The piston according to claim 7,
- wherein the binder resin of the inner and outer coating layers is at least one of a polyamide-imide resin, a polyimide resin and an epoxy resin;
- wherein the inner coating layer contains 50% by weight or less of at least one of graphite and molybdenum disulfide as a solid lubricant based on the total weight of the inner coating layer;
- and
- wherein the outer coating layer contains 50 to 95% by weight of at least one of graphite and molybdenum disulfide as a solid lubricant based on the total weight of the outer coating layer.
Dependencies are inferred from the claim text.