JPS58197454A - Piston crown - Google Patents

Abstract

PURPOSE:To obtain sufficient joint strength of the coating layer of insulation material, by employing such structure where a conductive porous metal having three dimensional mesh structure is secured onto the fire contact face of a piston crown then insulation member is laminated through injection welding. CONSTITUTION:Insulation member 6 is injection welded onto a porous metal 5 secured to the fire contacting face 1a. Since the surface of the porous metal 5 is coarse, the powder of insulation member blown through injection welding will enter complexly into the interior then laminated and exposed and finally form the insulative coating layer same as the conventional injection welding layer. Both of them are intertwined complexly at the inteface to provide strong jointing force through a kind of wedge effect thus to prevent the fall-out during usage due to the thermal stress or vibration.

Description

[Detailed Description of the Invention] Conventionally, a piston crown generally has a configuration as shown in Figure 1. There is a seal on the outer periphery of the stock body 1':
(not shown) constitutes the sliding part.
is inserted, and.

It is cooled by oil.

The contact surface 1'a forms a part of the combustion chamber of the internal engine and is therefore exposed to combustion gas at a crystal temperature, so it is generally cooled from the inside.

However, in order to effectively utilize the thermal energy f' generated by combustion and increase the thermal motion of the internal engine, it is necessary to utilize the heat from the combustion chamber wall, including the contact surface 1'a4 of Company J. loss? It is necessary to minimize it as much as possible. For this purpose, conventionally, each member constituting the combustion chamber wall, such as a cylinder crown, a cylinder liner, and a cover. It has been commonly used to cut off heat by manufacturing the intake and exhaust valves with a heat insulating material, or by coating a portion of each member with a heat insulating material. The former is being applied in recent years as a ceramic material to automobile engineering: J-jishi, etc., but it is still at an experimental stage and there are many technical problems that need to be solved before it can be put into practical use.

In particular, in the case of large-scale, high-output machines: J-jishi, the reliability and quality assurance of ceramics has not yet reached the experimental stage f. On the other hand, the latter method has been tested experimentally.
has been implemented. came. However, with this method, the insulation material]
- Tee: J-layer binding: , / Because the bonding strength of the crown contact surface with the metal surface is weak, thermal stress and vibration during use]
- Tishif pigeons (accidents of them being released and falling off occur frequently, so they have not been put into practical use.

In view of the above, it is an object of the present invention to provide a heat-insulating piston cap that has a structure that can be put into practical use by creating sufficient bonding strength between the heat-insulating material and the contact surface. This is the purpose. For this reason, the present invention fixes porous metal having continuity in a three-dimensional network structure to the contact surface of the piston J crown that heats ~,
It is assumed that it has a structure covered with heat insulating material on top of it.

One embodiment of the present invention> This will be explained in detail with reference to FIGS. 42 and 3.

FIG. 2 shows the important H and a elements of the present invention, in which a porous metal 5 having a three-dimensional mesh structure and having continuity is fixed to the contact surface 1a of the piston crown body 1. The situation is shown below. The catalyst rki1° and the porous metal 5 are
Since it is generally fixed by brazing, it is a metal-to-metal bond and has sufficient bonding strength, unlike the bonding of dissimilar materials such as aluminum and metal. Contact surface 1 of porous metal 5
In addition to brazing, fixing to a may also be done by methods such as resistance bath welding, and diffusion. As a result of experiments, sufficient bonding strength was obtained using the Izugaku method.

Is Figure 3 the final configuration of the present invention? At the plane shown in the figure, IF? This shows a situation where the heating material 6 is directly irradiated. Since the surface of the porous metal 5 before thermal spraying is extremely uneven, the heat insulating powder sprayed by the thermal spraying enters the inside of the porous metal bar M45 in a complicated manner, is laminated, and becomes uneven on the porous metal. exposed to the surface, jt eventually.

The same insulation layer as the conventional d-irradiation layer 1 is formed, but the boundary between the insulation coat 6 and the porous metal 5 has a structure in which the two are roughly intertwined, creating a strong bond due to the wedge effect of the elm. have power.

There is no need to worry about it falling off due to thermal stress or shaking during use.

The porous metal 5 can be made of common metals or alloys, but is usually made of Ni-Cr-IJ! A heat-resistant alloy having a composition system of +Nt-Cr is most suitable. Further, the heat insulating material 6 is generally made of ceramic, and the ceramic is made of Zr(h 2 ).

M2O, oxide system, and SIC+ Si3N< l
There are non-oxidized @-types such as B4". Among these, there are
, heat resistant.

ZrO2, which has good corrosion resistance and whose coefficient of thermal expansion is close to that of metal, is most suitable for reducing thermal stress.

The present invention is characterized in that it has a 6-porous nonmetallic material having a three-dimensional network structure between the contact surface of the piston cap and the VFT thermal coating layer.

The reason why porous metal was used was to increase the bonding strength of the thermally sprayed thermally-sprayed metal layer and reduce thermal stress and vibration during use. This is to prevent them from falling off, but in addition to this, porous metals generally have small heat transfer passages, so they have considerable heat insulating properties, although this varies depending on their porosity.

In general, the thicker the thermal insulation layer is, the greater the insulation effect is, but the conventional m It D layer is.

The thicker the insulation, the lower the degree of separation, and the limited thickness of the coating.
and the metal that makes up the contact surface are directly connected.

Since they are not joined and are interposed through the porous metal bar #g, there are no problems such as those mentioned above (the thickness of the coach insino can be made to have a sufficiently high heat insulating property and magnetization).

As described above, there is a piston crown according to the present invention.

It increases the heat insulation of the contact surface, improves the quality and durability of the internal combustion engine, and improves the performance of the internal combustion engine.

In addition, from the standpoint of energy saving, it has industrial benefits that are not found in conventional products.

[Brief explanation of the drawing]

FIG. 41 is a sectional view showing an example of a conventional piston crown, and FIGS. 2 and 43 are sectional views showing configuration 2 of the piston crown of the present invention. 1... Histoshi crown body, 1 &... Histoshi + d contact surface, 2... Piston rigidity, 3... Bolt hole, 4...
...Cooling surface, 5...Porous metal, 6...Insulating coating: JjiI-

Claims (1)

[Claims] In a piston crown of an internal combustion engine, a porous metal having a three-dimensional mesh groove fixed to a contact surface of the piston crown;
A piston crown characterized in that it comprises a heat insulating material fixed to the porous metal upper part by m-irradiation.