JPH039551Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a cylinder head gasket used in an internal combustion engine, and particularly relates to a cylinder head gasket with a shim in which a shim for adjusting surface pressure is embedded between the bores. .

[Conventional technology]

The cylinder head gasket is disposed between the cylinder head and the cylinder block, and is compressed by the cylinder head and cylinder block by tightening the head bolts, so that three liquids, combustion gas, cooling water, and lubricating oil, can be collected. Seal at the same time.

Conventionally, as shown in FIGS. 10 to 13, a cylinder head gasket usually consists of a core plate 1, asbestos 2 and 3 provided on both its upper and lower surfaces, and covering the outside of the asbestos 2 and 3 at the periphery of the bore. It consists of a grommet 4 provided as shown in FIG.

Generally, when the cylinder head 5 is made of aluminum alloy, since aluminum alloy has low rigidity, when the head bolts 6 are tightened, the lower surface of the cylinder head 5 is bent into a concave shape in a plane perpendicular to the bore center line O-O. There is a problem in that the surface pressure around the bore of the cylinder head gasket is lower than in the vicinity of the head bolt 6, causing gas to blow through between the bores.

In order to deal with this problem, conventionally,
Publication No. 109547, Publication No. 152164 of Utility Model Publication No. 59-152164, Publication of Utility Model Application No. 109547
As shown in Japanese Patent No. 58-109542, a shim 7 of a constant thickness as shown in FIGS. 14 and 15 is embedded in the portion between the bores of the cylinder head gasket to reduce the surface pressure between the bores. Techniques have been proposed for adjusting the temperature to increase it.

[Problem that the invention attempts to solve]

However, in the cylinder head gasket having the above structure, the cylinder head gasket deforms from the state shown in Fig. 11 to the state shown in Fig. 12 before and after the head bolt is tightened, and because the shim thickness is constant, the shim ends E , F increases, and the surface pressure of the shim central portion D decreases, resulting in uneven surface pressure on the shim contact surface. For this reason, even if the surface pressure is adjusted by inserting shims, the desired surface pressure may not be obtained during engine operation in the center of the shim, which is the most important part for sealing, and there is still a risk that gas may blow through. There was a problem.

The object of the present invention is to ensure a sufficiently large surface pressure between the bores in a cylinder head gasket in which shims are inserted between the bores, and to prevent gas from blowing between the bores.

[Means for solving problems]

To achieve this objective, the cylinder head gasket with shims between the bores of the present invention is interposed between the cylinder head and the cylinder block, and includes a core plate, asbestos affixed to both upper and lower sides of the core plate.
In a cylinder head gasket with a shim between the bores, which has a grommet that covers the outside of the asbestos at the circumferential edge of the bore and a shim member for adjusting surface pressure embedded in the gasket between the bores, the shim is located on the cylinder head side. The cross-sectional shape of the shim in the direction perpendicular to the line between the grommet and the core plate and connecting the center of the bore is
It consists of a central convex shape with maximum thickness at the position of the line connecting the bore centers and minimum thickness at both ends.

[Effect]

After tightening the head bolts, the lower surface of the cylinder head deforms into a concave shape around the line connecting the bore centers in a cross section perpendicular to the line connecting the bore centers, and the load distribution on the cylinder head gasket increases at both ends where the shim contacts. Even if the shim tries to become smaller at the center, the embedded shim is formed with a thicker center in the cross section perpendicular to the line connecting the bore centers, so the surface pressure on the shim contact surface is uniform. The desired surface pressure is ensured during engine operation, and gas blow-through between the bores does not occur.

〔Example〕

Hereinafter, preferred embodiments of the cylinder head gasket with inter-bore shims according to the present invention will be described with reference to the drawings.

First Embodiment FIGS. 1 to 6 show a first embodiment of the present invention. To explain the overall configuration using FIGS. 1 to 4, a cylinder head gasket 13 is interposed between the cylinder head 11 and the cylinder block 12, and a head bolt (not shown) is inserted into the head bolt hole 14. Pressure is applied by tightening.

The cylinder head gasket 13 has a core plate 15 made of a metal plate, asbestos 16 and 17 provided on both upper and lower sides of the core plate 15, and a grommet 18 that covers the outside of the asbestos 16 and 17 at the peripheral edge of the cylinder bore. Grommet 18 is made of a heat-resistant metal such as stainless steel and protects asbestos 16, 17 from impact from combustion gases and chemical changes.

A shim 19 is embedded in the portion of the cylinder head gasket 13 located between the bores. The shim 19 is formed so that, in a cross section perpendicular to the line OO connecting the bore centers, the shim 19 has the maximum thickness at the line OO connecting the bore centers and the minimum thickness at both ends.
5 and 6 show only the shim 19, one surface of which is a flat surface 19a, and the other surface comprised of a curved surface 19b with a convex central portion.
The shim 19 is attached to the back surface of a portion 18a of the grommet 18 on the cylinder head side.
In pasting, preferably the curved surface 1 of the shim 19
9b side faces the back surface of the grommet 18a, so that the deformation of the cylinder head 11 in the middle and height follows the shim curved surface 19b.

Second Embodiment FIG. 7 shows only the shim 20 of a cylinder head gasket 13 according to a second embodiment of the present invention. The shim 20 is connected to the line O-O connecting the bore centers.
In the cross section perpendicular to , the line O connecting the bore center
-O portion is formed to have the maximum thickness and both ends are formed to have the minimum thickness. One side of the shim 20 is a flat surface 20a,
The other surface consists of a trapezoidal surface 20b with a convex central portion. The shim 20 is attached to the back surface of a portion 18a of the grommet 18 on the cylinder head side, and preferably, the flat surface 20a of the shim 20 is attached to the grommet 18.
It is attached in contact with the back side of the The rest of the structure is similar to that of the cylinder head gasket of the first embodiment.

Third Embodiment FIG. 8 shows a cross section of a cylinder head gasket 13 according to a third embodiment of the present invention in a direction perpendicular to a line connecting the bore centers. The shim 21 provided between the bores is formed to have a maximum thickness at a line O-O connecting the bore centers and a minimum thickness at both ends. One surface of the shim 21 is a flat surface 21a, and the other surface is a curved or trapezoidal surface 21a with a convex central portion. The shim 21 is attached to the back surface of the portion 18a of the grommet 18 on the cylinder head side, with the raised surface 21b facing the cylinder head side portion 18a of the grommet 18. In such a structure, when the asbestos 16 and 17 are clamped by the cylinder head 11, the densities of the asbestos 16 and 17 are different, and the surface pressure at the center becomes larger than that at both ends.

Fourth Embodiment FIG. 9 shows a fourth embodiment of the cylinder head gasket of the present invention. In this example,
The shim 22 provided between the bores is formed to have a maximum thickness at the center and a minimum thickness at both ends in a plane perpendicular to the line O-O connecting the centers of the cylinder bores. In the cross section including -O, as shown in FIG. 9, the shim 22
Both end faces 22a and 22b in the width direction are grommet 18.
are in contact with the back surfaces of the bore side portions 18b, 18c. Bore side portions 18b, 18 of grommet 18
C is the part facing the combustion chamber that is exposed to the highest temperature, and the heat from this part is carried to the center part through the shim 22 by the end surface contact structure of the shim 22, and is transferred to the cylinder head 11, cylinder block 1
Escaped to 2.

Next, the operation of the first to fourth embodiments configured as described above will be explained.

When the cylinder head gasket 13 is sandwiched between the cylinder head 11 and the cylinder block 12 and the head bolt is tightened, the cylinder head gasket 13 is clamped between the cylinder head 11 and the cylinder block 12. At this time, since the tightening force near the head bolt is large and the cylinder head 11 made of aluminum alloy has relatively low rigidity, the cylinder deforms into a mid-height shape in the cross section perpendicular to the line O-O connecting the bore center line. . For this reason, as described above, in the conventional cylinder head gasket, the surface pressure between the bores becomes small, and there is a risk that gas may blow through between the bores.

However, in the present invention, shims 19 and 2 are provided between the bores of the cylinder head gasket 13.
0, 21 or 22 are provided, and since the shims 20 and 22 have a convex shape at the center in a cross section perpendicular to the line O-O connecting the bore centers, they follow the deformation of the cylinder head 11. Therefore, the surface pressure of the shim abutting portion is made uniform, and the desired surface pressure is ensured between the bores. By selecting the shape of the convex shape, the surface pressure of the cylinder head gasket 13 can be made completely uniform in the direction perpendicular to the line O-O connecting the bore centers, or it is possible to make the surface pressure in the center part more uniform than in other parts. It is also possible to increase the pressure. This eliminates the problem of reduced surface pressure at the center of the shim that would occur when using shims with a constant plate thickness.
This prevents gas from blowing between the bores. To prevent this gas from blowing out, the cylinder head 11
There is essentially no need for measures that increase the weight and cost, such as increasing the rigidity of the device.

In addition, since both ends of the shims 19, 20, 21, and 22 have the minimum thickness, the back surface of the grommet 18 and both ends of the shims do not come into contact with each other at an acute angle. Damage is prevented.

Furthermore, between the first and second embodiments, the convex surface changes more smoothly in the first embodiment, which is preferable in terms of uniformity of surface pressure, but the trapezoidal surface in the second embodiment is easier to machine. It has the advantage of being easy. Even if the convex surface 21b of the shim 21 faces downward as in the third embodiment, the density of the asbestos 16 and 17 changes during tightening, so it is affected by the effect of equalizing the surface pressure. Effects similar to those in the example can be obtained.

Furthermore, if both end surfaces of the shim 22 are brought into contact with the back surfaces of the bore side portions 18b and 18c of the grommet 18 as in the fourth embodiment, the contact area with the grommet 18 will be increased, and the shim will come into contact with the grommet from the side surfaces 18b and 18c. Heat conduction to the cylinder head 11 side through the cylinder head 22 is increased, and the heat dissipation effect is improved.

[Effect of idea]

Therefore, when using the cylinder head gasket of the present invention, the shim thickness is made larger at the center and smaller at both ends in a plane perpendicular to the line connecting the centers of the cylinder bores, so that the cylinder head does not bend when the head bolt is tightened. Regardless of the situation, the gasket surface pressure between the bores does not decrease, the surface pressure becomes uniform, and gas blow-by between the bores can be prevented. Furthermore, by adopting a convex shape that minimizes the thickness at both ends of the shim, damage to the grommet caused by both ends of the shim is alleviated.

With the above-mentioned shim structure, gas blow-through can be prevented without increasing costs due to the steel build-up of the cylinder head to prevent deformation of the cylinder head.

[Brief explanation of drawings]

1 is a sectional view of a cylinder head gasket with a shim between the bores according to the first embodiment of the present invention after the head bolt is tightened; FIG. 2 is a sectional view of the gasket shown in FIG. 1 before the head bolt is tightened; The figure is a cross-sectional view of the gasket in the direction perpendicular to that in Figure 1, Figure 4 is a plan view of an internal combustion engine equipped with the gasket shown in Figure 1, Figure 5 is a plan view of the shim, and Figure 6 is a front view of the shim. FIG. 7 is a front view of a gasket shim according to a second embodiment of the present invention, FIG. 8 is a sectional view of a gasket according to a third embodiment of the present invention, and FIG. 9 is a front view of a shim of a gasket according to a fourth embodiment of the present invention. A sectional view of such a gasket, FIG. 10 is a plan view of a conventional cylinder head gasket, and FIG. 11 is a sectional view of a conventional cylinder head gasket.
12 is a modified view of the gasket in FIG. 10, FIG. 13 is a sectional view of the gasket in FIG. 10 in a direction perpendicular to FIG. 11, and FIG.
The figure is a front view of the gasket shim in Figure 10,
FIG. 5 is a plan view of the shim shown in FIG. 14. 11...Cylinder head, 12...Cylinder block, 13...Cylinder head gasket, 1
5... Core plate, 16, 17... Asbestos, 18...
... Grommet, 19, 20, 21, 22... Sim.

Claims (1)

[Scope of utility model registration request] It is interposed between the cylinder head and the cylinder block, and has a core plate, asbestos disposed above and below the core plate, and a grommet that covers the outside of the asbestos at the peripheral edge of the bore, and further includes a portion between the bores. In a cylinder head gasket with a shim between the bores and a built-in shim member for adjusting surface pressure, the shim is placed between the grommet on the cylinder head side and the core plate,
A cylinder head with shims between the bores, characterized in that the cross-sectional shape of the shim in the direction perpendicular to the line connecting the bore centers is a central convex shape having a maximum thickness at the position of the line connecting the bore centers and a minimum thickness at both ends. Gasket.