Piston for internal combustion engine, internal combustion engine including this piston, and manufacturing method of this piston
AssigneeToyota Jidosha Kabushiki Kaisha
InventorHideo Yamashita
Life of this patent
Estimating the term…
Abstract
There is provided a piston for an internal combustion engine, the piston including: a heat-shielding film provided to an upper surface of a land part of the piston, the heat-shielding film having a lower thermal conductivity than a piston base material and having a lower heat capacity per unit volume than the piston base material; and a first heat-retaining film provided to a side surface of the land part, the first heat-retaining film having a lower thermal conductivity than the piston base material and having a higher heat capacity per unit volume than the heat-shielding film.
Claims6
A piston for an internal combustion engine, the piston comprising:
- a heat-shielding film provided to an upper surface of a land part of the piston, the heat-shielding film having a lower thermal conductivity than a piston base material and having a lower heat capacity per unit volume than the piston base material;
- and
- a first heat-retaining film provided to a side surface of the land part, the first heat-retaining film having a lower thermal conductivity than the piston base material and having a higher heat capacity per unit volume than the heat-shielding film,
- wherein the heat-shielding film is an anodized film,
- wherein the heat-shielding firm is not provided to the side surface of the land part,
- wherein the first heat-retaining film is provided to a part of a side surface of a top land, and the top land is a portion of the land part further on the upper side than a groove in which a top ring is fitted, and
- wherein a surface roughness of the first heat-retaining film is lower than a surface roughness of the heat-shielding film.
A piston for an internal combustion engine, the piston comprising:
- a heat-shielding film provided to an upper surface of a land part of the piston, the heat-shielding film having a lower thermal conductivity than a piston base material and having a lower heat capacity per unit volume than the piston base material;
- and
- a first heat-retaining film provided to a side surface of the land part, the first heat-retaining film having a lower thermal conductivity than the piston base material and having a higher heat capacity per unit volume than the heat-shielding film,
- wherein
- a second heat-retaining film is provided to an inner wall surface of a cylinder that houses the piston,
- the second heat-retaining film is provided at such a position that the second heat-retaining film faces the side surface of the land part when the piston is located at a bottom dead point, and
- the second heat-retaining film has a heat capacity per unit volume lower than that of the piston base material and higher than that of the heat-shielding film.
A manufacturing method of a piston for an internal combustion engine, the piston including:
- a heat-shielding film provided to an upper surface of a land part of the piston, the heat-shielding film having a lower thermal conductivity than a piston base material and having a lower heat capacity per unit volume than the piston base material;
- and
- a first heat-retaining film provided to a side surface of the land part, the first heat-retaining film having a lower thermal conductivity than the piston base material and having a higher heat capacity per unit volume than the heat-shielding film, the manufacturing method comprising:
- forming the heat-shielding film on the upper surface of the land part by anodizing the piston base material;
- and
- after forming the heat-shielding film, forming the first heat-retaining film on the side surface of the land part by forming a film of an insulating material, the insulating material having a lower thermal conductivity than the piston base material and having a higher heat capacity per unit volume than the heat-shielding film.
Dependencies are inferred from the claim text.