JPH0117636Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The gasket for internal combustion engines according to this invention can be used between the cylinder block and the cylinder head of an internal combustion engine, especially a pre-chamber type diesel engine.
It is used to maintain airtightness between the two.

(Prior Art) As shown in Fig. 1, a pre-chamber type diesel engine has a narrow communication hole 4 in the upper part of a main combustion chamber 3 at the upper end of a cylinder 2 into which a piston 1 is fitted. There is an auxiliary room 5 that leads to 3.

During operation, fuel is injected into this auxiliary chamber 5 and pre-combusted, and the combustion gas generated by this pre-combustion expands and is ejected into the main combustion chamber 3 through the communication hole 4 along with unburned fuel. Main combustion occurs in chamber 3.

By the way, such a sub-chamber 5 is formed by fitting an insert 8 having a communication hole 4 into a recess 7 formed on the lower surface of the cylinder head 6, so that the lower surface of the cylinder head 6 and the cylinder block are connected to each other. A gasket 10 is sandwiched between the upper surface of the gasket 9 and the upper surface of the gasket 9.
Maintains airtightness between both sides.

As shown in FIG. 2, this gasket 10 is made of a gasket material 11 made of a core material such as an iron plate with a hook or a wire mesh, with layers of asbestos, graphite, etc. formed on both sides of the core material.
A circular hole (not necessarily a perfect circular hole) 12 is bored in accordance with the diameter of the cylinder 2, and a metal grommet 13 is attached to the inner peripheral edge of the circular hole 12. .

On one side of this grommet 13, a substantially semicircular tongue portion 14 is formed in a portion facing the insert 8 provided on the lower surface of the cylinder head 6, and the upper surface of this tongue portion 14 is formed to face the insert 8. The lower half of the 8 is supported. gasket 1
If the internal combustion engine to which 0 is to be installed is a multi-cylinder type, circular holes 12 corresponding to the number of cylinders are bored in the gasket 10, and a grommet 13 is installed in each circular hole 12. In some cases, the edges of the grommets to be removed are connected to each other as shown in FIG. 6, so that the grommets for one engine can be handled as one unit.

(Problems to be Solved by the Invention) However, the gasket for an internal combustion engine constructed and used as described above has the following disadvantages.

That is, the insert 8 that fits into the recess 7 on the lower surface of the cylinder head should be made to perfectly match the size of the recess 7 in order to prevent it from shaking within the recess 7 during operation of the internal combustion engine. Although ideal, the lower surface of the insert 8 may protrude slightly (0.1 m/m or less) from the lower surface of the cylinder head 6 due to manufacturing errors.

For this reason, when the cylinder head 6 and cylinder block 9 are overlapped with the gasket 10 held between them, and the two are connected with bolts, this insert 8
The part of the tongue 14 of the grommet 13 that the bottom surface of the insert 8 contacts is particularly strongly pressed, and compared to the case where the bottom surface of the insert 8 does not protrude, when the tightening force of the bolt is constant, the insert The contact force between the lower surface of the cylinder head 8 and the upper surface of the tongue portion 14 becomes large, and the contact force between the other lower surface portions of the cylinder head and the gasket 10 portion decreases.

The part where the airtight effect of the gasket 10 is most required is the annular part of the grommet 13 attached to the peripheral edge of the circular hole 12, so the tongue-shaped part 14 is
It is undesirable for the contact force at this portion to become unnecessarily large, as this may cause a drop in airtightness due to a decrease in the contact force at the peripheral edge of the circular hole.

In this way, in order to eliminate the insufficient airtightness between the cylinder head 6 and the cylinder block 9 due to the contact force between the lower surface of the insert 8 and the upper surface of the tongue-shaped portion 14 being too large, the arrangement shown in FIG. As shown, a crescent-shaped through hole 15 is bored in the center of the tongue 14,
It is also conceivable that only the peripheral edge of the tongue portion 14 be in contact with the lower surface of the insert 8.

The tongue-shaped part 14 has a through hole 15 in the center like this.
Since the pressure at which the upper surface of the peripheral edge of the insert 8 contacts the lower surface of the insert 8 is almost the same per unit area as when the through hole 15 is not provided, the entire lower surface of the insert 8 contacts the tongue-shaped portion 14. Power is through hole 15
The force with which the other parts are pressed between the lower surface of the cylinder head 6 and the upper surface of the cylinder block 9 increases accordingly. Therefore, the abutting force on the peripheral edge of the circular hole 12 of the gasket 10 is also increased, and sufficient airtightness is ensured in this area.

However, simply forming the through hole 15 in the center of the tongue portion 14 as described above still has disadvantages as described below.

That is, as shown by reference numeral A in FIG. 1, the temperature of the upper corner of the cylinder 2 where the auxiliary chamber 5 is provided becomes particularly high during operation of the internal combustion engine, and the gasket 10 in this area also heats up considerably. This heating causes extreme unevenness in temperature distribution and tends to cause the gasket material 11 to deteriorate.

As shown in FIG. 3, when a through hole 15 is formed in the center of the tongue 14 of the metal grommet 13, the part of the gasket material 11 that comes into direct contact with the heated grommet 13 during operation is particularly heated, causing the gasket to heat up. It also becomes a cause of hastening thermal deterioration of the material 11.

Furthermore, since the peripheral edge of the tongue 14 and the peripheral edge of the lower surface of the insert 8 still come into contact with each other with considerably strong pressure, when the inner peripheral edge of the sharp through hole 15 comes into contact with the lower surface of the insert 8, the lower surface of the insert 8 It may also cause damage to the

Japanese Patent Application No. 58-64655 (see Japanese Patent Application Laid-Open No. 58-187559) solves the above-mentioned problem by overlapping a tongue without a through hole with a tongue with a through hole. Although a possible structure has been shown, it instead causes the following disadvantages.

That is, in the case of the structure disclosed in the above patent application,
It is unavoidable that a step is formed at both ends of the tongue due to the change in the number of metal plates, and high-pressure combustion gas in the cylinder tends to leak through this step.

The gasket for an internal combustion engine of the present invention has a structure in which two grommets are joined together, and a through hole is provided only in the tongue-shaped portion of one grommet, thereby solving all of the above-mentioned disadvantages.

(Means for Solving the Problem) The gasket for an internal combustion engine of the present invention, like the conventional gasket for an internal combustion engine described above, is equipped with a grommet having a tongue-shaped portion on the periphery of a circular hole bored in the gasket material. It consists of things to do.

Furthermore, in the gasket for an internal combustion engine of the present invention, the grommet has a two-layer structure in which a pair of grommet elements each having a closed annular shape surrounding the entire circumference of the circular hole are stacked on top of each other. The tongue-shaped part of one grommet element located at the gasket is not provided with a hole, but the tongue-shaped part of the other grommet element sandwiched between this tongue part and the gasket material is provided with a through hole. There is.

(Function) In the case of the gasket for an internal combustion engine of the present invention constructed as described above, of the two tongue-shaped parts,
Since only the thickness of the outer circumferential portion of the lower surface of the cylinder head that comes into contact with the insert circumferential edge is increased, the tongue-shaped portion does not waste the force of pressing the gasket.

Furthermore, since the part that comes into direct contact with the insert is non-porous, there is no possibility of thermal deterioration of the gasket material or damage to the bottom surface of the insert.

Furthermore, a continuous airtight line is formed around the circular hole without forming a step around the entire circumference.
Airtightness inside the cylinder can be maintained reliably.

(Example) Next, the present invention will be explained in more detail while explaining the illustrated embodiment.

FIG. 4 shows a grommet 16 used in the gasket for an internal combustion engine of the present invention. The grommet 16 consists of a pair of grommet elements 16a and 16b that fit into each other. One of the grommet elements 16a has a substantially semicircular tongue portion 18a formed outside a part of a ring-shaped main body 17a, and a short cylindrical vertical wall 19a on the inner peripheral edge of the main body 17a.
The entire structure is made of a thin plate of corrosion-resistant and heat-resistant metal such as stainless steel (the drawing is thicker than it actually is for clarity).

The other grommet element 16b, like the above-mentioned grommet element 16a, has a substantially semicircular tongue portion 18b formed partially outwardly of a ring-shaped main body 17b, and a short cylindrical tongue portion 18b on the inner peripheral edge of the main body 17b. However, one of the grommet elements 16 mentioned above forms a vertical wall 19b.
Unlike the case shown in FIG. 1A, a crescent-shaped through hole 20 is formed in the center of the tongue portion 18b. The inner diameter of the vertical wall 19b is also slightly larger than that of the vertical wall 19a, and is formed so that the vertical wall 19a of one grommet element 16a can fit inside the vertical wall 19b of the other grommet element 16b.

Grommet 1 consisting of a pair of grommet elements 16a, 16b, each formed as described above.
As shown in FIG. 3, the gasket 6 is installed inside the circular hole 12 of the gasket material 11 to form a gasket for an internal combustion engine.

That is, the vertical wall 19 of one grommet element 16a
a into the vertical wall 19b of the other grommet element 16b, and
The vertical wall 19b of b is further inserted into the circular hole 12 made in the gasket material 11, and the vertical walls 19a and 19b protruding from the other end surface of the gasket material 11 are bent outward and caulked to form the vertical wall 19a. , 19b
The peripheral edge of the circular hole 12 of the gasket material 11 is held between the main bodies 17a and 17b.

In this state, the through hole 20 formed in the tongue portion 18b is covered by one of the tongue portions 18a. still,
In Figure 5, for clarity, gasket material 1
Grommet elements 16a, 16b compared to the thickness of 1
The thickness is drawn thickly. Also, gasket material 11
The grommet mounting portion is recessed when the grommet 16 is caulked, but this recess is also omitted from illustration.

The gasket for an internal combustion engine of the present invention constructed as described above has the tongue portion 18a facing the lower surface of the insert 8 on the lower surface of the cylinder head, similar to the conventional gasket 10 shown in FIGS. A through hole 20 is formed in the center of the other tongue 18b, which is held between the lower surface of the cylinder head and the upper surface of the cylinder block, and which is sandwiched between one tongue 18a and the gasket material 11. Therefore, the pressing force exerted by the lower surface of the insert 8 is not so large as a whole, as is the case with the tongue-shaped portion shown in FIG. It can be kept.

Further, because of one tongue-shaped portion 18a, the edge of the through hole 20 of the other tongue-shaped portion 18b does not come into contact with the lower surface of the insert 8, and the lower surface of the insert 8 is not damaged by the sharp edge.

In addition, heat is evenly distributed to the gasket material 11 by the non-porous tongue portion 18a, preventing extreme temperature unevenness and reducing thermal deterioration of the gasket material 11, which has great practical effects. .

Furthermore, compared to the case where the through hole 15 is formed in the tongue-like part of a gasket formed in one piece as shown in FIG. 3, if the thickness of the grommet as a whole is the same, This is effective in improving the airtightness of this area because pressure fluctuations near the peripheral edge of the area become gentle.

In addition, as shown in FIG. 6, when grommets to be attached to the upper ends of multiple cylinders are combined together,
The same concept can be used to form a through hole 22 in this joint 21 to prevent unnecessary pressure from being generated in this joint.

(Effects of the invention) The gasket for internal combustion engines of the present invention is configured and operates as described above, so it can be installed between the lower surface of the cylinder head and the upper surface of the cylinder block of a diesel engine having a sub-combustion chamber. It has great practical effects as a gasket that not only reliably maintains airtightness, but also has little thermal deterioration and excellent durability.

[Brief explanation of drawings]

Fig. 1 is a vertical sectional view of the upper part of a diesel engine, Fig. 2 is a plan view of a conventional gasket to be attached to the diesel engine, Fig. 3 is a partial plan view of a grommet with a through hole in the tongue portion, and Fig. 4 The following figures show an embodiment of the present invention: Fig. 4 is an exploded perspective view of the grommet, Fig. 5 is a cross-sectional view showing the grommet attached to the gasket material, and Fig. 6 is an integrated grommet for multiple cylinders. FIG. 1: Piston, 2: Cylinder, 3: Main combustion chamber,
4: Communication hole, 5: Sub-chamber, 6: Cylinder head,
7: recess, 8: insert, 9: cylinder block, 10: gasket, 11: gasket material, 1
2: circular hole, 13: grommet, 14: tongue, 1
5: Through hole, 16: Grommet, 16a, 16b:
Grommet element, 17a, 17b: main body, 18
a, 18b: tongue-like part, 19a, 19b: standing wall, 2
0, 22: Through hole, 21: Joint part.

Claims (1)

[Scope of utility model registration request] In a gasket for an internal combustion engine, in which a grommet 16 having a tongue-shaped portion is attached to the peripheral edge of a circular hole 12 formed in a gasket material 11, each of the grommets 16 surrounds the entire circumference of the circular hole 12. A pair of closed annular grommet elements 16a, 1
The grommet element 16a has a two-piece structure in which the grommet elements 6b are stacked one on top of the other, and the tongue-like part 18a of one of the grommet elements 16a located on the surface is not provided with a hole, and the grommet element 16b is sandwiched between the tongue-like part 18a and the gasket material 11. A gasket for an internal combustion engine, characterized in that a through hole 20 is provided in the tongue portion 18b of the grommet element 16b.