JP6971746B2 - An engine component having a heat shield film and a method for manufacturing the engine component. - Google Patents

Description

The present invention relates to an engine component having a heat shield film and a method for manufacturing the engine component.

Conventionally, in the engine of a vehicle such as an automobile, measures have been taken to improve the cooling loss in the engine in order to improve the work efficiency due to the heat energy generated by the fuel.

As one of the measures for improving the cooling loss, it is known to form a heat shield film made of ceramics on the wall surface of the combustion chamber of the engine. Ceramics have a lower thermal conductivity than aluminum or the like, which is generally used as a vehicle member, and have heat resistance, so that they have the effect of shielding the wall surface of the combustion chamber from heat.

However, since ceramics generally have a high heat capacity per unit mass (that is, have a high specific heat), in an engine having a ceramic heat shield film, the wall surface temperature of the combustion chamber constantly rises due to continuous operation of the engine. do. As a result, there are problems that the intake efficiency of the engine is lowered and knocking occurs due to abnormal combustion due to an increase in temperature in the fuel chamber.

In order to solve this problem, the heat-shielding film is required to have heat resistance, low thermal conductivity, and a low heat capacity per unit mass (that is, low specific heat). Air can be mentioned as an optimum material having a low thermal conductivity and a low specific heat. As a structure for taking air into the heat shield film, for example, in Patent Document 1, an alumite film, which is an anodized film grown from aluminum, is formed as a heat shield film on the wall surface of an engine component constituting an engine combustion chamber. Things are listed.

The alumite film has a large number of holes extending in the film thickness direction, and the engine component described in Patent Document 1 is a seal laminated with the alumite film and the alumite film to seal the upper surface of the holes of the alumite film. It has a heat shield film composed of a pore material layer. Further, as the sealing material, polysilazane or polysiloxane containing silica as a main component having heat resistance is used.

Japanese Unexamined Patent Publication No. 2015-96634

In the heat-shielding film described in Patent Document 1, low thermal conductivity and low specific heat can be realized by the air held inside the pores formed in the alumite film, and the average temperature is maximum due to the sealing material layer. Heat resistance can be ensured for a high temperature engine combustion chamber of about 300 ° C.

However, the heat-shielding film described in Patent Document 1 has a problem that the mechanical strength of the heat-shielding film is lowered due to a large number of holes formed in the alumite film.

Since the combustion chamber of an engine becomes hot and high pressure, high mechanical strength that can withstand high pressure conditions is required. However, the mechanical strength of the alumite film becomes brittle due to the large number of holes extending in the columnar direction in the film thickness direction, and the mechanical strength is high enough to withstand long-term use only by reinforcement with a sealing material layer made of silica. It was difficult to secure the strength.

The present invention has been made in view of the above problems, and an object thereof is an engine component having a heat-shielding film having low thermal conductivity and low specific heat, and excellent heat resistance and mechanical strength, and the engine configuration. The present invention is to provide a method for manufacturing a member.

In order to achieve the above object, one embodiment of the present invention is an engine component having a heat shield film on a wall surface constituting the engine combustion chamber, in which the heat shield film is roughened. Ri Do from the air-containing layer inorganic hollow fine particles of silicon are embedded in the wall surface, said in an air-containing layer, wherein the wall has a number of recesses, said inorganic hollow particles are embedded in the interior of the recess and said that you are.

According to this configuration, it is possible to obtain a heat-shielding film having a low thermal conductivity and a low heat capacity due to the air contained in the inorganic hollow fine particles constituting the heat-shielding film. Further, since the inorganic hollow fine particles are embedded in the roughened wall surface of the engine component, the mechanical strength of the heat shield film is maintained. Further, since the hollow fine particles holding air are made of a silicon-based inorganic material having high heat resistance, they are excellent in heat resistance to a high temperature engine combustion chamber.

Further, in order to achieve the above object, one embodiment of the present invention is a method for manufacturing an engine component having a heat shield film on the wall surface constituting the engine combustion chamber, with respect to the wall surface of the engine component. a surface roughening step of forming a plurality of depressions in the wall surface roughening treatment and facilities, and the inorganic hollow fine particles of silicon collides with the wall surface of the roughened the engine component member, the concave portion of the wall surface It is characterized by including an embedding step of embedding the inorganic hollow fine particles in the inside of the above.

According to this configuration, in the rough surface treatment step, the wall surface of the engine component is roughened and has an uneven shape. Therefore, by colliding the inorganic hollow fine particles with the roughened wall surface, the inorganic hollow is formed. Fine particles easily enter the recesses on the wall surface of the engine component. This makes it possible to form a heat-shielding film in which silicon-based inorganic hollow fine particles are embedded in the wall surface of the engine component. The heat-shielding film has a low thermal conductivity and a low heat capacity due to the air contained in the inorganic hollow fine particles, so that the cooling loss of the engine can be reduced.

Further, since the inorganic hollow fine particles are embedded in the wall surface of the engine component, the mechanical strength of the heat shield film is maintained. Further, since the hollow fine particles holding air are made of a silicon-based inorganic material having high heat resistance, it can be used as a heat-shielding film having excellent heat resistance for a high-temperature engine combustion chamber.

Further, one embodiment of the present invention is characterized in that, in the manufacturing method, in the rough surface treatment, the engine constituent member is roughened by mechanically applying a force to the wall surface.

According to this configuration, the wall surface of the engine component itself is roughened by applying a mechanical force. Therefore, due to the high mechanical strength and heat resistance of the engine component, the mechanical strength and heat resistance of the heat shield film are obtained. It is possible to improve the sex.

Further, one embodiment of the present invention is characterized in that, in the manufacturing method, the rough surface treatment is an anodizing treatment for the engine constituent member.

According to this configuration, by performing anodizing treatment on the engine component, an anodic oxide film having a large number of holes can be formed on the surface of the engine component. Therefore, in the embedding process, this anodic oxidation can be performed. By embedding the inorganic hollow fine particles inside the pores of the film, the inorganic hollow fine particles can be retained on the surface of the engine component. Further, the embedded inorganic hollow fine particles can improve the mechanical strength of the anodic oxide film constituting the heat shield film.

According to the present invention, since the silicon-based inorganic hollow fine particles have a heat-shielding film embedded in the wall surface of the engine component, the heat-shielding film has heat resistance and mechanical strength, and is intermediate to inorganic. The air contained in the particles can make the heat shield film have low thermal conductivity and low specific heat.

The schematic diagram which shows the engine combustion chamber structure using the engine component which has the heat-shielding film which concerns on embodiment of this invention. Sectional drawing which shows the heat-shielding film formed on the wall surface of a piston. The figure explaining the formation method of the heat-shielding film.

An engine component having a heat-shielding film according to the present invention will be described in detail. FIG. 1 is a schematic view showing an engine combustion chamber structure 1 using an engine component having a heat shield film according to an embodiment of the present invention. The engine combustion chamber structure 1 of FIG. 1 is applied to an engine of a vehicle such as an automobile.

The engine combustion chamber structure 1 includes a cylinder block 12, a cylinder head 13, a piston 14, a spark plug 16, an intake valve 17, and an exhaust valve 18, which are engine components constituting the engine combustion chamber 2.

The cylinder block 12 has a cylindrical cylinder 11 that forms the engine combustion chamber 2. The piston 14 has a substantially cylindrical shape, and is configured to be able to reciprocate by sliding inside the cylinder 12.

The cylinder head 13 covers the upper surface of the cylinder block 12 and has a combustion chamber ceiling portion 13a that covers the upper surface of the cylinder 11. The spark plug 16, the intake valve 17, and the exhaust valve 18 are attached to the cylinder head 13.

The spark plug 16 has an electrode portion that serves as an ignition portion at the end portion, and the end portion is attached so as to project from the combustion chamber ceiling portion 13a into the engine combustion chamber 2. The intake valve 17 is configured to be able to open and close the intake passage 13b formed in the cylinder head 13, and the exhaust valve 18 is configured to be able to open and close the exhaust passage 13c formed in the cylinder head 13.

In the engine combustion chamber structure 1, a mixed gas mixed with fuel is supplied to the engine combustion chamber 2 surrounded by the cylinder 11, the combustion chamber ceiling portion 13a of the cylinder head 13, and the piston 14 by opening the intake valve 17. , Combustion by being ignited by the ignition plug 16. This combustion pushes down the piston 14. Exhaust gas generated by combustion is exhausted to the outside of the engine combustion chamber 2 by opening the exhaust valve 18.

In the present embodiment, the piston 14, the cylinder block 12, the cylinder head 13, the intake valve 17, and the exhaust valve 18 have a heat insulating film 30 on the wall surface constituting the engine combustion chamber 2. Specifically, a heat shield film is formed on the upper surface 14a of the piston 14, the combustion chamber ceiling portion 13a of the cylinder head 13, and the surfaces of the intake valves 17 and the valve heads 17a and 18a of the valve heads 17a and 18a on the engine combustion chamber 2 side. 30 is formed. Although not shown, the heat shield film 30 may be further formed on the inner wall surface 11a of the cylinder 11.

FIG. 2 is a cross-sectional view showing a heat shield film 30 formed on the upper surface 14a which is a wall surface of the piston 14. The heat-shielding film 30 is made of an air-containing layer in which silicon-based inorganic hollow fine particles are embedded inside a roughened upper surface 14a.

The piston 14, which is an engine component, is made of a metal material, and in the present embodiment, it is made of an aluminum alloy.

The film thickness of the heat shield film 30 formed on the upper surface 14a of the piston is about 20 to 200 μm, preferably about 50 to 100 μm. The porosity of the heat shield film 30 is preferably in the range of about 20 to 90%, more preferably about 30 to 80%, from the viewpoint of maintaining the strength while retaining a large amount of air.

The inorganic hollow fine particles 40 have a micro-level size and are made of a silicon-based inorganic material (for example, a glass material such as silica). The size of the inorganic hollow fine particles 40 is preferably about 5 to 40 μm in diameter, more preferably about 16 to 20 μm in diameter and about 0.5 to 2 μm in shell thickness. The inorganic hollow fine particles 40 have higher heat resistance than the metal material constituting the piston.

In the illustrated example, the inorganic hollow fine particles 40 are spherical, but the shape is not limited to this, and any shape may be used as long as it is hollow and can hold air inside. Further, the structure may be a mixture of inorganic hollow fine particles 40 having different sizes.

It is preferable to use the inorganic hollow fine particles 40 having a softening temperature at which the shape change occurs, which is equal to or higher than the melting point of the metal material constituting the engine component. The inorganic hollow fine particles 40 of the present embodiment are made of a glass material having a softening temperature equivalent to the melting point (660 ° C.) of the aluminum alloy constituting the piston 14.

Next, a method of manufacturing the engine component having the heat shield film 30 described above will be described. Here, as an example of the manufacturing method, a method of forming the heat shield film 30 on the upper surface 14a of the piston 14 which is an engine component will be described. As for the cylinder block 12, the cylinder head 13, the intake valve 17, and the exhaust valve 18, the heat shield film 30 can be formed on the wall surface by the same method as described below.

First, as shown in FIGS. 3A and 3B, a rough surface treatment is applied to the upper surface 14a of the flat piston 14 to form micro-level irregularities on the upper surface 14a (rough surface treatment step). As the rough surface treatment, for example, the upper surface 14a can be mechanically roughened by blasting such as sandblasting by spraying an abrasive on the upper surface 14a, machining, laser irradiation, or the like. Further, as another rough surface treatment, the surface can be roughened by etching with a chemical agent or by performing anodizing treatment (anodizing treatment) on the upper surface 14a. In the present embodiment, the upper surface 14a is roughened by a mechanical force.

By this rough surface treatment, a large number of recesses 32 are formed on the upper surface 14a of the piston. The recess 32 has an internal space similar to the size of the inorganic hollow fine particles 40 so that the inorganic hollow fine particles 40 can be embedded. In the example shown in FIG. 3B, a recess 32 having a depth similar to the diameter of the inorganic hollow fine particles 40 is formed, and the diameter of the recess 32 is slightly smaller than the diameter of the inorganic hollow fine particles 40 and is maximum. The hole diameter is slightly larger than the diameter of the inorganic hollow fine particles 40. There is.

Next, as shown in FIG. 3C, the inorganic hollow fine particles 40 are made to collide with the roughened upper surface 14a of the piston, and the inorganic hollow fine particles 40 are embedded (buried) inside the recess 32 formed in the upper surface 14a. Incorporation process).

The collision / embedding of the inorganic hollow fine particles 40 with respect to the upper surface 14a can be performed, for example, by using a shot peening device that projects an innumerable projection material made of granules onto a metal surface at high speed. In this shot peening device, the inorganic hollow fine particles 40 are used as a projection material and are projected onto the upper surface 14a at high speed, so that a part thereof enters the recess 32 and becomes an embedded state. Further, since the depth of the recess 32 is about the same as the size of the inorganic hollow fine particles 40, one inorganic hollow fine particle 40 can be inserted into one recess 32.

In the embedding step of the present embodiment, when the inorganic hollow fine particles 40 collide with the upper surface 14a of the piston, the temperature of the upper surface 14a raised by the collision energy exceeds the melting point of the aluminum alloy constituting the piston 14 at a projection speed. The inorganic hollow fine particles 40 are collided with each other. As a result, when the inorganic Liu sky fine particles 40 collide, the upper surface 14a of the piston melts and can be attached to the surface of the hollow inorganic fine particles 40, and as a result, the inorganic hollow fine particles 40 are firmly held inside the upper surface 14a of the piston. Will be done. The projection speed is not limited to this, and may be such that the temperature of the upper surface 14a becomes equal to or lower than the melting point at the time of collision, and the inorganic hollow fine particles 40 are embedded in the recess 32 by colliding at a high projection speed. If possible.

The surface of the embedded inorganic hollow fine particles 40 may be partially exposed from the upper surface 14a of the piston, but it is preferable that the surface is coated with an aluminum alloy melted at the time of collision.

By embedding the inorganic hollow fine particles 40 in the upper surface 14a of the piston through the rough surface treatment step and the embedding step in this way, the heat shield film 30 which is an air-containing layer is formed on the upper surface 14a of the piston 14.

In the manufacturing method described above, the upper surface 14a of the piston 14, which is an engine component, is roughened to form a large number of recesses 32 on the upper surface 14a. Therefore, in the embedding step, the roughened wall surface is formed. By colliding the inorganic hollow fine particles 40, the inorganic hollow fine particles 40 can be embedded in the recess 32. Further, the inorganic hollow fine particles 40 collide with the wall surface at high speed to deform the upper surface 14a, so that the inorganic hollow fine particles 40 are firmly held inside the piston upper surface 14a. Further, by melting the piston upper surface 14a roughened by the energy when the inorganic hollow fine particles 40 are collided and embedding the inorganic hollow fine particles 40, the holding strength of the inorganic hollow fine particles 40 becomes higher.

Further, the piston 14 having the above-mentioned heat-shielding film has a heat-shielding film 30 having a low thermal conductivity and a low heat capacity due to the air contained in the inorganic hollow fine particles 40 embedded in the upper surface 14a. Further, since the inorganic hollow fine particles 40 are made of a silicon-based inorganic material having high heat resistance, the heat-shielding film 30 having excellent heat resistance can be obtained for the engine combustion chamber 2 which becomes hot. Further, since the inorganic hollow fine particles 40 are embedded in the upper surface 14a of the piston 14, the mechanical strength of the heat shield film 30 can be maintained.

In the rough surface treatment step, a plurality of recesses 32 having different hole diameters and depths may be provided, and in the embedding step, a large number of inorganic hollow fine particles 40 having different diameters may be projected. As a result, the inorganic hollow fine particles 40 having a small diameter can be embedded in the concave portions 32 having a small internal space, and the inorganic hollow fine particles 40 having a large diameter can be embedded in the concave portions 32 having a large internal space. The inorganic hollow fine particles 40 can be reliably embedded in the recess 32 while loosening the permissible range of the above.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention. For example, in the above-described embodiment, the heat shield film 30 is formed on the entire upper surface 14a of the piston 14 which is an engine component, but the heat shield film 30 may be formed only on a part of the upper surface 14a. good.

1 Engine combustion chamber structure 11 Cylinder 12 Cylinder block 13 Cylinder head 14 Piston 14a Piston upper surface 17 Intake valve 18 Exhaust valve 30 Heat shield film 32 Recess 40 Inorganic hollow fine particles

Claims (4)

In an engine component having a heat shield film on the wall surface constituting the engine combustion chamber,
The Saeginetsumaku is Ri Do from the air-containing layer inorganic hollow fine particles of silicon are embedded in the roughened wall surface of the engine component member,
An engine component characterized in that, in the air-containing layer, the wall surface has a large number of recesses, and the inorganic hollow fine particles are embedded in the recesses. A method for manufacturing an engine component having a heat shield film on the wall surface constituting the engine combustion chamber.
A surface roughening step of forming a plurality of depressions in the wall surface by facilities surface roughening with respect to the wall surface of the engine component member,
A step of colliding silicon-based inorganic hollow fine particles with the roughened wall surface of the engine component and embedding the inorganic hollow fine particles inside the concave portion of the wall surface.
A method for manufacturing an engine component, which comprises. The manufacturing method according to claim 2, wherein in the rough surface treatment, the engine component is roughened by mechanically applying a force to the wall surface. The manufacturing method according to claim 2, wherein the rough surface treatment is an anodizing treatment for the engine component.

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