JPS587079Y2 - Piston head for internal combustion engine - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to improvements in piston heads for internal combustion engines.

Conventionally, by combining a metal piston head body with a head plate made of heat-resistant ceramics with low thermal conductivity, it reduces heat loss during internal combustion engine operation, increases output, reduces hydrocarbon concentration, and improves fuel efficiency. We are trying to reduce this.

As for this coupling structure, generally proposed methods include casting a ceramic head plate integrally with the metal piston head body, or mechanically coupling the two using fastening members such as screws and screws. has been done.

However, the former structure has various problems to be solved, such as cracks occurring in the ceramic material due to the extreme difference in thermal expansion coefficient between the metal material and the ceramic material.
According to the latter structure, due to the long-term operation of the internal combustion engine,
The disadvantage is that the fastening member loosens due to thermal cycles, reciprocating motion, and vibrations, and the size of the fastening member is limited, especially in small pistons, and there is no room for existing loosening prevention mechanisms. Problems remain with mass production.

This invention was devised in view of the above-mentioned drawbacks of the mechanical coupling structure between the metal piston head body and the ceramic head plate. The object of the present invention is to provide a ceramic-metal composite piston head that is held in place.

Hereinafter, the present invention will be explained based on embodiments shown in the accompanying drawings.

As shown in Figures 1 and 2, the top of the piston head (see Figure 2) made of metal such as high aluminum alloy cast iron is covered with a flat plate made of ceramics such as alumina, silicon nitride cordierite, etc. The head plate 2 is placed thereon, and a plurality of fastening members 3 made of bolts, for example, are provided so as to penetrate from above the head plate 2 into the piston head 1.
is inserted, and the head plate 2 is fixed to the piston head 1 with a predetermined fastening force.

Although not shown, a thin metal piece, ceramic wool, or the like may be provided as a cushioning material between the fastening member 3 and the head plate 2 and between the head plate 2 and the piston head 1.

An important feature of the present invention is that after the head plate 2 is fixed to the top of the piston head 1 by the fastening member 3,
The joining portion between the fastening member 3 and the piston head 1, that is, the fastening portion is melt-bonded.

For this purpose, the head of the fastening member 3 and an appropriate part of the piston head 2 are sandwiched between electrodes, and a large current is applied for a short period of time to heat the fastening part between the fastening member 3 and the piston head 2. The fastening portion is fused and bonded.

The material of the fastening member 3 is preferably the same as that of the piston head 1 in order to properly perform the fusion bonding, but from the viewpoint of mechanical strength, the fastening member 3 is preferably made of stainless steel or the like. It is desirable to use metal with excellent mechanical strength.

However, if the piston head 1 is an aluminum alloy, the aluminum alloy of the piston head 1 may melt excessively during fusion bonding due to the difference in melting point of the art materials, and in extreme cases, the piston head may be deformed.

In this case, as shown in FIG. 3, a fastening fitting 4 made of stainless steel or the like of the same quality as the fastening member 3 is placed at the fastening part of the fastening member 3 and the piston head 1. By passing a large current between the wearing fitting 4 and the fastening member 3 for a short period of time, the fastening portion of the art material may be fused and bonded.

In order to pass a large current between the fastening member 3 and the fastening fitting 4, it is necessary to provide an insertion hole 5 that communicates with the fastening fitting 4 from the outside of the piston head 1 when casting the piston head 1. .

In order to install the fixing fitting 4, it is convenient for production to set the fixing fitting 4 in a predetermined position and cast the piston head 1 at the same time, but in this case,
In order to firmly and tightly connect the piston head main body and the fastening metal fitting 4, it is preferable to previously provide a plurality of grooves or a plurality of irregularities on the outer surface of the fastening metal fitting 4.

According to the embodiment shown in FIG. 3 described above, since the fastening member 3 and the fastening portion of the piston head 1 are made of metal with excellent mechanical strength, it can withstand harsh conditions compared to the embodiment shown in FIG. Excellent durability under various conditions.

With the above-mentioned simple structure, the present invention can effectively prevent the loosening and rattling of the fastening member, which are fatal drawbacks of the mechanical connection structure of the metal piston head and the ceramic head plate, and can prevent the normal operation of art materials. Since the connection is permanently maintained and no special mechanism or parts are added, it has significant advantages such as being more effectively applicable to small pistons where space is limited.

[Brief explanation of drawings]

FIG. 1 is a plan view of a piston head according to the present invention. FIG. 2 is a sectional view taken along the line X--X in FIG. 1, and FIG. 3 is a sectional view showing a preferred embodiment of the present invention. 1...Metal piston head, 2...
Ceramic head plate, 3... Fastening member.

Claims (1)

[Scope of utility model registration request] A ceramic head plate is placed on the top of a metal piston head, and a fastening member inserted from the plate side is used to properly attach the plate to the piston bed, and the fastening member and the fastening portion of the piston head are connected. A piston head for an internal combustion engine characterized by being melt-bonded.