JPS5819325Y2 - Internal combustion engine piston head member - Google Patents

Description

[Detailed description of the invention] This invention has a structure suitable for being cast into the top of the piston using ceramic, which has excellent heat insulation and heat resistance, and has poor thermal shock resistance and tensile strength, making it susceptible to cracking. It relates to a piston head member of an internal combustion engine,
The object of the present invention is to provide a piston head member that is extremely advantageous when used as a casting for a piston cast from an aluminum alloy.

Focusing on the excellent heat insulation and heat resistance of ceramics, attempts to improve combustion efficiency by insulating the high-pressure combustion gas compressed or injected in the cylinders of internal combustion engines are an obvious way to improve fuel efficiency and prevent pollution. It is where it is proposed.

However, molded ceramic insulation materials are inherently inferior in thermal shock resistance and tensile strength, so they cannot compensate for the brittleness of aluminum alloys, which can crack and fail due to thermal shock and thermal stress received during cooling. Mass production is not possible due to unresolved technical issues, and it is still in the testing stage.

The present invention compensates for the brittleness of ceramic insulation materials and facilitates piston casting, and one embodiment thereof will be described below.

In Figures 1 and 2, reference numeral 1 is a ceramic heat insulating material whose top surface has a slightly raised offshore center to form a pointed recess 2 and whose bottom surface 3 is almost smooth. The piston head member A is fixed by shrink-fitting into a ring 4, and complement side through holes 5, which constitute an example of anti-rotation unevenness, are provided at approximately equal intervals on the side circumference of the metal ring 4.

As shown in FIG. 2, the head member A is cast into the head of a piston P formed by casting an aluminum alloy, and the head member A is made of aluminum alloy casting material flowing into the plurality of through holes 5 of the metal ring 4. Prevents removal and rotation.

As shown in FIG. 3, the metal ring 4 to which the ceramic heat insulating material 1 of the piston head member A shown in the above embodiment is fitted may be provided with an inward flange 6 at its upper end to serve as a stopper to prevent removal. .

At this time, the fit between the ceramic heat insulating material 1 and the metal ring 4 only needs to be a tight fit.

In each of the above embodiments, the ceramic heat insulating material 1 uses oxides such as alumina and silica, nitrides such as aluminum nitride and silicon nitride, and carbides such as silicon carbide and titanium carbide.

Further, the metal ring 4 is made of a heat-resistant metal having a small coefficient of thermal expansion, and 13 chromium stainless steel is suitably used as an example thereof.

As clarified from the above description, the piston head member of the present invention replaces the ceramic heat insulating material 1 constituting the combustion chamber on the top surface of the piston with the piston P cast from an aluminum alloy.
The metal ring 4 cushions the thermal shock applied to the ceramic insulation material 1 during casting, protects the ceramic insulation material 1 from thermal shock, and prevents damage such as cracking. The molten aluminum alloy flowing into the large number of through holes 5 acts to prevent rotation and removal, and the leading edge of the aluminum alloy flowing into the through holes 5 comes into contact with a small portion of the ceramic heat insulating material. , the action of the rotation stopper and removal stopper is effective to effectively prevent involuntary removal or rattling of the ceramic heat insulating material 1 due to the reaction of the combustion gas explosion. The piston head member has the advantage that by casting the piston head made of aluminum alloy, it is possible to streamline the production of internal combustion engine pistons whose top surfaces are made of ceramic heat insulating material.

[Brief explanation of drawings]

Figure 1 is an isolated side sectional view of the piston head member of the present invention, Figure 2 is an isolated side sectional view of the piston head member of the present invention;
The figure is a side sectional view showing the casting into the piston, and FIG. 3 is a side sectional view of a modified embodiment. 1 → Ceramic insulation material, 4 → Metal ring, 5 → Through hole, A →
Piston head member, P → Piston.

Claims (1)

[Scope of utility model registration request] The ceramic heat insulating material that makes up the top surface of the piston is fitted into a metal ring with a small coefficient of thermal expansion to prevent thermal shock, and the molten aluminum alloy that is the casting material for the piston is poured into the metal ring when the piston is cast. A piston head member for an internal combustion engine, characterized by having a large number of substantially radial through holes.