Engine and piston
Any one or more members of an engine, that is, a piston, a cylinder head and a valve, has a wall face disposed face-to-face to a combustion chamber, and the wall face is coated by a heat-insulation coating film. The heat-insulation coating film includes a heat-insulative layer formed on a surface of the wall face, and an inorganic-system coated-film layer formed on a surface of the heat-insulative layer. The heat-insulative layer includes a resin, and first hollow particles buried inside the resin and exhibiting an average particle diameter being smaller than a thickness of the heat-insulative layer. The inorganic-system coated-film layer includes an inorganic compound.
1. An engine comprising:
a cylinder block having a bore;
a piston fitted into said bore to reciprocate therein so as to form a combustion chamber therein;
a cylinder head having a valve bore closing said combustion chamber and communicating with said combustion clamber; and
a valve opening and closing said valve bore;
at least one of said piston, said cylinder head and said valve having a wall face disposed face-to-face to said combustion chamber and a heat-insulation coating film coating said wall face;
said heat-insulation coating film comprising:
a heat-insulative layer formed on a surface of said wall face; and
an inorganic-system coated-film layer formed on a surface of the heat-insulative layer;
said heat-insulative layer comprising:
a resin; and
first hollow particles buried into the resin and exhibiting an average particle diameter being smaller than a thickness of said heat-insulative layer; and
said inorganic-system coated-film layer comprising:
an inorganic compound and
second hollow particles exhibiting an average particle diameter being smaller than a thickness of said inorganic-system coated-film layer;
said inorganic-system coated-film layer comprising an outermost superficial-layer section and an interior section disposed on a more inner side than the outermost superficial-layer section therein in a thickness-wise direction thereof and disposed face-to-face to said heat-insulative layer; and
an average particle diameter of said second hollow particles included in said outermost superficial-layer section is smaller than an average particle diameter of said second hollow particles included in said interior section.
2. The engine as set forth in claim 1 , wherein the average particle diameter of said first hollow particles falls within a range of 1 μm to 100 μm.
3. The engine as set forth in claim 1 , wherein the thickness of said organic system coated-film layer is from 10 μm to 300 μm.
4. The engine as set forth in claim 1 , wherein said inorganic compound constituting said inorganic-system coated-film layer comprises one or more members selected from silica, zirconia, alumina, and cerin.
5. The engine as set forth in claim 1 , wherein the average particle diameter of said second hollow particles included in the outermost superficial-layer section falls within a range from 10 nm to 500 nm.
6. The engine as set forth in claim 1 , wherein:
the thickness of said heat-insulative layer is from 10 μm to 2,000 μm; and
the average particle diameter of said first hollow particles is from 1 μm to 100 μm.
7. The engine as set forth in claim 1 , wherein said heat-insulative layer exhibits a porosity, of from 5% or more to 90% or less when an apparent volume of said heat-insulative layer is taken as 100%.
8. The engine as set forth in claim 1 , wherein a surface roughness of said outermost superficial-layer section of said inorganic system coated-film layer included in said heat-insulation coating film is smaller than another surface roughness of the wall face.
9. A piston fitted into a bore to reciprocate therein so as to form a combustion chamber therein, said piston comprising:
a wall face disposed face-to-face to said combustion chamber and coated by a heat-insulation coating film coating said wall face, said heat-insulation coating film comprising:
a heat-insulative layer formed on a surface of said wall face; and
an inorganic-system coated-film layer formed on a surface of the heat-insulative layer, said heat-insulative layer comprising:
a resin; and
first hollow particles buried into the resin and exhibiting an average particle diameter being smaller than a thickness of said heat-insulative layer; and
said inorganic-system coated-film layer comprising:
an inorganic compound and second hollow particles exhibiting an average particle diameter being smaller than a thickness of said inorganic-system coated-film layer, said inorganic-system coated-film layer comprising an outermost superficial-layer section and an interior section disposed on a more inner side than is the outermost superficial-layer section therein in a thickness-wise direction thereof and disposed face-to-face to said heat-insulative layer; and an average particle diameter of said second hollow particles included in said outermost superficial-layer section is smaller than an average particle diameter of said section hollow particles included in said interior section.
10. The piston as set forth in claim 9 , wherein a surface roughness of said inorganic-system coated-film layer included in said heat-insulation coating film is smaller than another surface roughness of the wall face.
11. The engine as set forth in claim 1 , wherein said inorganic-system coated-film layer is a coating film comprising silica.
12. The engine as set forth in claim 1 , wherein the average particle diameter of said second hollow particles included in said interior section falls within a range from 1 μm to 500 μm.
13. The engine as set forth in claim 10 , wherein said inorganic-system coated-film layer is a coating film comprising silica.