JP2595215Y2 - Head gasket for internal combustion engine - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a head gasket formed by pressing a soft material sheet containing no asbestos on a metal core.

[0002]

2. Description of the Related Art Conventionally, there has been known a head gasket in which a grommet is provided on the entire surface layer of a soft material of a head gasket formed of a metal core and a soft material. Conventionally, asbestos has been used as a soft material, but a head gasket containing no asbestos has been demanded due to pollution. However, the structure of the cylinder head is complicated due to the formation of air supply / exhaust ports, head bolt holes, water jackets, etc., and the rigidity of the lower surface of the head generally differs depending on the location. Must be determined so that the surface pressure distribution necessary to seal each of them is obtained.

In order to secure the surface pressure of the gas sealing grommet at the bore opening, the bolt hole of the head is used as a through boss to obtain the tightening force of the head bolt, that is, the axial force.
The surface pressure of the gasket in the bolt hole also increases. further,
When the engine is operated, fluctuations in the in-cylinder pressure due to combustion are repeatedly applied to the head bolt at all times. Therefore, a decrease in restoring force occurs. As a result, the axial force of the head bolt is reduced, and the initially set distribution of the surface pressure distribution of the gasket is also broken, so that there is a problem that leakage of gas, oil and water occurs. In that respect, soft materials containing asbestos could be applied relatively favorably, but those containing no asbestos would cause the above-mentioned problems.

In general, various seal structures around a head bolt hole are known. For example, Japanese Utility Model Laid-Open Publication No. 2-69174 discloses a structure in which a grommet is covered over the upper and lower surfaces of a soft material. However, in the known technique, when the head bolt is tightened, the soft material is crushed, so that so-called settling of the soft material cannot be prevented, and the soft material cannot be maintained at a predetermined thickness.

Further, Japanese Utility Model Application Laid-Open No. 57-31550 discloses a grommet which covers a soft material or a substrate which does not use a soft material. However, such known techniques cannot prevent the soft material from settling. Conventionally, asbestos is relatively resistant to settling, and thus was suitable as a soft material for a gasket. However, when asbestos is not used as a soft material, leakage due to settling of the soft material cannot be prevented due to long-term use.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to prevent the reduction of the axial force of the head bolt during long-term use without causing settling in the soft material even if asbestos is not used as the soft material. An object of the present invention is to provide a head gasket for an internal combustion engine that does not cause leakage.

[0007]

According to the present invention, in a head gasket of an internal combustion engine in which a soft material sheet (3) containing no asbestos is crimped on a metal core (2), a cylinder is mounted on a cylinder block (6). In a bolt hole (5) of a head bolt (8) for tightening the head (7), a grommet (4) having a U-shaped cross section and directly pressed to the metal core (2) is provided with the metal core (2) interposed therebetween. The soft material sheet (3) is provided at a position without the grommet (4), and the thickness of the grommet (4) is slightly smaller than the thickness of the gasket (1) without tightening the head bolt (8). It is so thin that the gasket (1) has the same thickness when the head bolt (8) is tightened to a specified torque.

[0008]

[Explanation of operation and effect] Therefore, when the head bolt is tightened to the cylinder head, the axial force of the head bolt is secured by the grommet, and the fluctuation of the tightening force of the head bolt caused by the fluctuation of the in-cylinder pressure is directly pressed to the metal core. Since the grommet is received, a decrease in axial force is prevented. The pressure fluctuation applied to the soft material sheet is relatively small, so that the soft material does not settle and can be used for a long period of time.

[0009]

Embodiments will be described below with reference to the drawings.

1 and 2, a head gasket 1 composed of a metal core 2 and a sheet 3 of a soft material not containing asbestos has a bolt hole 5 for tightening a head bolt.
Is provided. The bolt hole 5 is provided with a grommet 4 having a U-shaped cross section which is directly press-fitted only to the metal core 2. Therefore, the soft material sheet 3 is provided at a place where the grommet 4 is not provided as shown in the figure. When the cylinder head 7 is tightened to the cylinder block 6 by the head bolt 8 with a specified torque, the grommet 4 and the gasket 1 are configured to have the same thickness.

Therefore, in FIG. 1, the gasket 1 fastened by the head bolt 8 has the thickness set by the grommet 4 provided in the bolt hole 5 and does not change even when the in-cylinder pressure fluctuates repeatedly. There is no reduction in the axial force of the head bolt.

[0012]

[Effects of the Invention] As described above, according to the present invention, the following excellent effects can be obtained. (A) Since the pressure fluctuation generated in the head bolt is covered by the metal core and the grommet, it is possible to prevent a decrease in the axial force of the head bolt even during long-term use. (B) Since pressure fluctuation is not relatively used for the soft material, settling can be prevented, and gas leakage and water leakage can be prevented. (C) Therefore, a head gasket with improved durability can be provided.

[Brief description of the drawings]

FIG. 1 is a view taken along line AA of FIG. 2 showing one embodiment of the present invention.

FIG. 2 is a plan view of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Head gasket 2 ... Metal core 3 ... Soft material 4 ... Grommet 5 ... Head bolt hole 6 ... Cylinder block 7 ... Cylinder head 8 ... Head bolt

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A 2-69174 (JP, U) JP-A 57-31550 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16J 15/12 F02F 11/12 F16J 15/08

Claims (1)

(57) [Scope of request for utility model registration] In a head gasket of an internal combustion engine in which a soft material sheet (3) containing no asbestos is crimped to a metal core (2), a head bolt (8) for fastening a cylinder head (7) to a cylinder block (6). ) Is inserted into the bolt hole (5) in the cross section U directly pressed to the metal core (2)
A grommet (4) in the shape of a letter is provided so as to sandwich the metal core (2), the soft material sheet (3) is provided at a position without the grommet (4), and the thickness of the grommet (4) is equal to the thickness of the head. The thickness of the gasket (1) is slightly smaller than the thickness of the gasket (1) when the bolt (8) is not tightened, and the gasket (1) is configured to have the same thickness when the head bolt (8) is tightened to a specified torque. A head gasket for an internal combustion engine.