JPH0117635Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a cylinder head gasket for an internal combustion engine, and particularly to a cylinder head gasket for use in a pre-chamber type diesel engine.

[Prior art]

Generally, in a sub-chamber type diesel engine, a sub-chamber (vortex chamber) is constituted by a hole provided in the cylinder head so as to open on the deck surface thereof, and a sub-chamber constituent member fitted into the hole. When the cylinder head and cylinder block are fastened together, the chamber component is pushed into the hole by the cylinder block through the cylinder head gasket, and is held in the normal insertion position.

For this reason, a portion of the cylinder head gasket used in the above-mentioned type of pre-chamber type diesel engine is sandwiched between the pre-chamber component and the cylinder block. When the gasket body is made of graphite material or equivalent material, a surface pressure adjusting plate generally called a back-up plate is used to obtain an appropriate surface pressure at the corresponding part with the subchamber component. Providing a plate member is considered.

[The problem that the idea attempts to solve]

In the sandwiched state, the gasket is dragged or hammered by the cylinder block, cylinder head, and sub-chamber constituent members due to thermal deformation and mechanical deformation, and as a result, the surface pressure adjusting plate member Similarly, the cylinder block, cylinder head, and pre-chamber constituent members are subjected to dragging and hammering, resulting in problems in crack resistance and durability. Particularly in the case where the surface pressure adjusting plate member is integrally provided with the cylinder bore grommet, dragging and hitting can cause fatigue to the grommet, leading to cracks in the grommet.

In view of the above-mentioned problems, the inventors of the present invention conducted a detailed experimental study on the function of cylinder head gaskets and found that the surface pressure adjusting plate member can be attached to either the cylinder block side or the cylinder head side of the gasket body. It works equally well even if it is installed on the surface, and the cylinder block has higher rigidity than the cylinder head due to its shape.Also, if the cylinder head is made of aluminum alloy and the cylinder block is made of cast iron, the cylinder Since the coefficient of thermal expansion of the block is smaller than that of the cylinder head, there is little thermal deformation, and for this reason, the surface pressure adjusting plate member is provided on the cylinder block side surface of the gasket body to improve crack resistance and durability. It has been found that this is advantageous in terms of sealing performance.

[Means to solve the problem]

The cylinder head gasket made of graphite material according to the present invention was created based on the above recognition, and when the cylinder head is made of aluminum alloy and the cylinder block is made of cast iron, It is characterized in that only the surface facing the cylinder block of the portion sandwiched between the auxiliary chamber constituent member and the cylinder block is constituted by a surface pressure adjusting plate member added thereto.

The surface pressure adjusting plate member may be provided integrally with the grommet, or may be provided separately from the grommet and affixed to the gasket body.

[Effect]

According to the above structure, the surface pressure adjusting plate member comes into contact only with the cylinder block, which has less thermal deformation and mechanical deformation than the cylinder head, and thus acts on the surface pressure adjusting plate member. The degree of dragging and hitting is reduced, and the durability of the surface pressure adjusting plate member is improved.

In this case, the gasket main body will come into direct contact with the subchamber constituent members, but since the graphite material forming the gasket main body has sufficient heat resistance, it will not suffer thermal damage. In addition, since the graphite material has excellent thermal conductivity, heat is efficiently released from the subchamber constituent members, and the heat load thereon can be reduced.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings.

Fig. 1 is an enlarged vertical sectional view of the main parts of a pre-chamber type diesel engine incorporating the cylinder head gasket according to the present invention, and Fig. 2 is a bottom view of the cylinder head gasket shown in Fig. 1. It is. In these figures, reference numeral 1 indicates a cylinder block, and reference numeral 2 indicates a cylinder head, both of which are fastened to each other by a fastening bolt (not shown) with a cylinder head gasket 20 in between.

The cylinder block 1 is made of cast iron, and a cylinder liner 3 is attached to the cylinder block 1. The cylinder liner 3 receives a piston 4 inside. The piston 4 defines a main chamber 5 between it and the cylinder head 2.

The cylinder head 2 is made of aluminum alloy, and the cylinder head 2 is provided with a hole 6 that opens on the surface facing the cylinder block 1, that is, on the deck surface. A sub-chamber 8 is formed in the cylinder head 2 by a hole 6 and a sub-chamber forming member 7 fitted into the hole 6. A spout 9 is bored in the auxiliary chamber constituent member 7, and the main chamber 5 and the auxiliary chamber 8 communicate with each other through the spout 9. A portion of the auxiliary chamber forming member 7 faces the upper surface of the cylinder block 1, and is prevented from coming off by the cylinder block 1 via a cylinder head gasket 20. Furthermore, the cylinder head 2 has a fuel injection nozzle 11 that injects liquid fuel into the subchamber 8 and a glow plug 12 that heats the liquid fuel injected into the subchamber 8.
is installed.

The cylinder head gasket 20 includes a plate-shaped gasket body 21 made of a graphite material or an equivalent material. The gasket body 21 is provided with a cylinder bore opening 22, a fastening bolt passage hole (not shown), a cooling water passage opening, and a lubricating oil passage opening. An annular grommet 23 is attached to the peripheral edge of the cylinder bore opening 22 by caulking. Grommet 2
3 is made of a heat-resistant metal such as stainless steel, and has an opening 22 for the cylinder bore to protect the gasket body from impact caused by combustion gas and chemical changes.
It covers the surrounding wall in the area. A surface pressure adjusting plate member 24 is provided on the surface of the cylinder block 1 side of the portion where the cylinder head gasket 20 is sandwiched between the auxiliary chamber forming member 7 and the cylinder block 1. This surface pressure adjustment plate member 24 is connected to the grommet 2.
The grommet 23 extends from the periphery of the grommet 23 and is integrated with the grommet 23.

The surface pressure adjusting plate member 24 constitutes a part of the surface facing the cylinder block 1, and in the installed state as shown in FIG.
and is in contact with the upper surface of the cylinder liner 3, and adjusts the surface pressure at this portion.

Since the surface pressure adjusting plate member 24 contacts only the cast iron cylinder block 1, which has less thermal deformation and mechanical deformation than the aluminum alloy cylinder head 2, the degree of dragging and hitting exerted by this can be reduced. This results in improved crack resistance and durability. In this case, the gasket body 21 will come into direct contact with the subchamber component 7, but since the graphite material has sufficient heat resistance,
This does not suffer thermal damage, and since graphite material has good thermal conductivity, the heat of the pre-chamber component 7 can be diffused to the cylinder block 1 and cylinder head 2 through the gasket body.
Overheating of the subchamber constituent members can be avoided.

The grommet 23 which integrally has the surface pressure adjustment plate member 24 is attached to the gasket body 21 by caulking the edge on the side where the surface pressure adjustment plate member 24 is not provided outward, and in this case, as shown in FIG. In the area indicated by A, there is a large amount of residual stress during caulking. However, since the surface pressure adjusting plate member 24 is provided on the side of the cylinder block 1 where there is less thermal deformation and mechanical deformation, this portion A is also located on the side of the cylinder block 1, causing cracks in the grommet 23. becomes less likely to occur.

3 and 4 show another embodiment of the cylinder head gasket according to the present invention. In this embodiment, a surface pressure adjusting plate member 25 corresponding to the auxiliary chamber constituent member 7 is provided separately from the grommet 23, and is attached to the cylinder block 1 of the gasket body 21.
It is attached to the side surface of the

Also in this embodiment, the durability of the cylinder head gasket is improved because the surface pressure adjusting plate member 25 contacts only the cylinder block 1.

Although the present invention has been described in detail with respect to specific embodiments above, it will be appreciated by those skilled in the art that the present invention is not limited to these and that various embodiments are possible within the scope of the present invention. It should be obvious.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view showing one embodiment of a pre-chamber type diesel engine incorporating a gasket according to the present invention, Fig. 2 is a bottom view of the cylinder head gasket shown in Fig. 1, and Fig. 3 4 is a bottom view showing another embodiment of the cylinder head gasket according to the present invention, and FIG. 4 is a sectional view taken along the line - in FIG. 3. 1... Cylinder block, 2... Cylinder head, 3... Cylinder liner, 4... Piston, 5
...Main chamber, 6... Hole, 7... Sub-chamber component, 8...
...Subchamber, 9...Nozzle port, 11...Fuel injection nozzle,
12... Glow plug, 20... Cylinder head gasket, 21... Gasket body, 22...
Cylinder bore opening, 23...grommet, 2
4, 25...Plate member for surface pressure adjustment.

Claims (1)

[Scope of utility model registration request] A cylinder head gasket made of a graphite material is interposed between a cylinder head made of an aluminum alloy and a cylinder block made of cast iron, in which a sub-chamber constituent member is fitted into a hole opening in the deck surface. Only the surface facing the cylinder block of the portion interposed between the auxiliary chamber constituent member and the cylinder block is constituted by a surface pressure adjusting plate member added thereto. cylinder head gasket.