JP3089929B2 - Cylinder head gasket - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder head gasket interposed between a cylinder block and a cylinder head of an internal combustion engine.

[0002]

2. Description of the Related Art There is known a metal cylinder head gasket having an opening for a cylinder bore and having a seal portion formed of a shim, a bead, a wiring and the like around the opening. In a conventional cylinder head gasket, as shown in FIGS. 12 and 13, when a cylinder head bolt (hereinafter, referred to as a head bolt) 1 is tightened, a seal portion (shim) 5 of a gasket 4 is supported on an upper deck 3 of a cylinder block 2. And a bending moment M is applied to deform the cylinder bore wall 6. Since this bending moment M is particularly strong in the vicinity 7 of the head bolt 1 and weak in the intermediate portion 8 between the two head bolts 1 and 1, the cylinder bore wall is seen in a plan view, and FIG.
As shown by a dashed line in the left part of the figure, the flower shape changes in a direction approaching the square. Such uneven deformation of the bore wall in the circumferential direction deteriorates the follow-up of the piston ring to the cylinder bore shape, increases the blow-by gas amount, and deteriorates oil consumption. In order to suppress this flower shape deformation,
Conventionally, various countermeasures have been proposed, for example, as disclosed in Japanese Utility Model Laid-Open Publication No. 1-107070. 1-140
In the metal head gasket disclosed in Japanese Patent Publication No. 070, the gasket is provided with another shim on the side opposite to the cylinder bore with respect to the head bolt. In this case, a bending moment is generated in the direction opposite to the bending moment generated at the seal portion as a fulcrum (moment that causes the flower shape deformation of the broken line in FIG. 11), thereby suppressing the flower shape deformation of the cylinder bore.

[0003]

However, Japanese Utility Model No. 1-1
In the gasket disclosed in Japanese Patent No. 40070, since a seal portion and a shim are provided on both sides of the head bolt to prevent deformation of the cylinder bore, the cost is increased. SUMMARY OF THE INVENTION An object of the present invention is to provide a cylinder head gasket that can suppress flower deformation of the cylinder bore wall without substantially increasing the cost.

[0004]

The cylinder head gasket according to the present invention for achieving the above object is as follows. In a cylinder head gasket having an opening for a cylinder bore and having at least a single sealing portion around the opening, the position of the sealing portion is set such that the center in the width direction of the sealing portion is farther from the cylinder bore near the cylinder head bolt and between the cylinder head bolts. Cylinder head gasket set close to

[0005]

When the cylinder head gasket of the present invention is used, the distance between the head bolt and the seal portion is small in the portion of the upper deck of the cylinder block near the bolt to which a large bolt axial force is applied (d of M = Fd). The moment becomes small because the distance between the bolt and the seal is large, so the moment becomes large, the moment distribution in the bore circumferential direction becomes uniform, and the circumferential bore deformation becomes uniform. As a result, flower-shaped deformation is less likely to occur on the bore wall.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described. Figure 1
3 shows a first embodiment of the present invention, FIGS. 4 to 7 show a second embodiment of the present invention, FIG. 8 shows a third embodiment of the present invention, and FIG. 9 shows a fourth embodiment of the present invention. FIG. 10 shows a fifth embodiment of the present invention, and the right part of FIG. 11 shows, by broken lines, deformation of a cylinder bore that occurs when the gasket of any of the first to fifth embodiments of the present invention is used. It is a thing. Components common to all the embodiments are denoted by the same reference numerals throughout the embodiments. First, the configuration and operation common to all embodiments of the present invention will be described with reference to, for example, FIGS. FIG. 1 shows a metal cylinder head gasket 14 (also referred to as a head gasket). Head gasket 14
Is a cylinder block 1 of the internal combustion engine, as shown in FIG.
The cylinder head 10 is clamped between the cylinder head 10 and the cylinder block 12 when the cylinder head 10 is fastened to the cylinder block 12 by the head bolt 11. The cylinder block 12 has a bore wall 16 defining a cylinder bore 20, and the bolt boss 19 and the bore wall 16 are connected to the upper deck 13.
Linked by As shown in FIG. 3, the fastening force of the head bolt 11 is applied to the bolt boss 19, and this force causes a moment M to act on the bore wall 16 via the upper deck 13. As shown in FIG. 2, the cylinder block 12 has a cylinder bore 20 and a bolt screw hole 2 for a head bolt.
1. A water hole 22 for circulating engine cooling water is provided. Similarly, as shown in FIG. 1, the head gasket 14 has a bore hole 23, a bolt hole 24, or a water hole as needed (not shown, but if provided, it is required to be located at a position corresponding to the water hole 22 of the block). Provided in a suitable size).

Each of the bore holes 23 is formed in the head gasket 14.
Is provided at least in a single layer so as to surround the seal.
The seal portion may be made of any of a shim, a bead, a wiring, and a grommet. FIG. 1 shows a case where the shim 15
From now, shows a case provided in single around the bore hole 23, FIG. 4 is shim seal portion from the inner circumference 2
5, a bead 26, and a shim 15 are provided three times around the bore hole 23. The position of at least the single seal portion 15 is such that the center in the width direction of the seal portion 15 is farther from the cylinder bore 20 (the bore hole 23 of the gasket 14) in the portion 17 near the head bolt 11, and
The portion 18 between the head bolts 11 is set to be close to the cylinder bore 20 (the bore hole 23 of the gasket 14). That is, d ₁ > d ₂ is set in FIG. In the head gasket 14, a seal portion such as a thickened portion is not formed in a portion of the head gasket 14 opposite to the bore hole 23 with the bolt hole 24 as a center. Does not occur, and the sealing portion located on the side of the bore hole 23 from the bolt hole 24 and the bolt hole 2
The seal portion located on the side opposite to the bore hole 23 from 4 does not deteriorate the adhesion of the gasket surface to the head surface and the block surface.

Next, a configuration specific to each embodiment will be described. In the first embodiment, as shown in FIGS. 1 to 3, the seal portion 15 is formed of a single shim around the bore hole 23. Hereinafter, the sign of the shim is also assumed to be 15. The shim 15 has a rectangular cross section of the same width and the same height over the entire circumference. The cross section of the shim has, for example, a width of 1.4 mm and a thickness of 0.1.
2 mm. The shim 15 has a shape in which the conventional shim 5 has a round shape as shown in FIG. 9, but in the first embodiment of the present invention, a square corner is rounded with a quarter circle. The shim 15 is moved closer to the head bolt 11 side. As shown in FIG. 2, there is no water hole on the straight line connecting the center of the bolt hole and the center of the cylinder bore of the cylinder block 12, and the bore wall 16 and the bolt boss portion 19 are
3

In the second embodiment, as shown in FIGS. 4 to 7, the seal portion 15 is formed in three layers around the bore hole 23 and is formed in order from the inner peripheral side to the outer peripheral side.
5, bead 26 and shim 15. Inner peripheral shim 2
5. The next bead 26 may have the same configuration as the conventional sealing structure, and has a circular shape in plan view. However, the position of the outermost shim 15 is such that the center in the width direction is the head bolt 1.
The portion 17 is set so as to be farther from the cylinder bore 20 (accordingly, the bore hole 23 of the gasket 14) and to be closer to the cylinder bore 20 (accordingly, the bore hole 23 of the gasket 14) at the portion 18 between the adjacent two head bolts. This position setting is performed as shown in FIGS.
5 is a perfect circle, the width of the shim 15 is wider than the width at the position of 0 ° and 90 ° at the position of 45 °, and as a result, the center of the shim 15 in the width direction is the bore 23 at the position of 45 °. You may make it farther away. Alternatively, as shown in FIG. 1, the shim shape may be made closer to a quadrangle shape while keeping the shim width constant, so that the center of the shim 15 in the width direction is 45 ° away from the bore 23.

Further, the thickness of the outermost shim 15 is set in the circumferential direction.
You may change it smoothly. FIG. 5 shows the shim 15 of FIG.
0 ° and 90 ° cross sections are shown, and FIG.
° shows a cross section. Shim thickness h at 0 ° and 90 °
₁₁, H₁₂Is the shim thickness h at 45 °_{twenty one}, H_{twenty two}Than,
Each thick (ie h₁₁> H_{twenty one}, H₁₂> H_{twenty two}).
Also, the maximum thickness h of the thickness of the outermost shim 15₁₁Is the inner circumference
The thickness h of the shim 25 on the side _sHas been thinner than.

In the second embodiment, the thickness of the outermost shim 15 is gradually changed in the width direction, and is tapered so that it becomes thinner toward the outer circumference. That is, h
_11> is a _{h 12, h 21> h 22} . FIG. 7 shows that the gasket 14 set as described above is attached to the cylinder block 12.
And a cylinder head 10 and a clamped state by a head bolt 11.

In the third embodiment, as shown in FIG. 8, the seal portion is composed of a grommet 27 attached to the inner periphery of the soft gasket 14. The width of the grommet 27 shown in FIG.
-The section of the A section and the section of the BB section are changed.
The width of the grommet 27 at the portion of the section -B (the portion near the bolt hole 24) is larger than the width of the grommet 27 at the portion of the section AA (the intermediate portion of the bolt hole).

In the fourth embodiment, as shown in FIG. 9, the seal portion is composed of a wire ring 28 attached to the soft gasket 14, and the wire ring 28 is supported by a grommet 27. The wiring 28 is shown in FIG.
Is near the bolt hole 24 at the BB cross section (the area near the bolt hole 24), and is close to the bore hole 23 at the AA cross section (the middle part of the bolt hole).

In a fifth embodiment, as shown in FIG. 10, a bead 2 formed on a metal gasket 14 has a seal portion.
Consists of nine. The bead 29 is close to the bolt hole 24 (far from the bore hole 23) in the BB cross section (the vicinity of the bolt hole 24) in FIG. 10, and in the AA cross section (the middle part of the bolt hole) in FIG. It is close to the bore hole 23. If the head gasket 14 is a soft gasket, the bead is replaced by a rubber print printed on the surface of the soft gasket.

Next, the operation will be described. First, an operation common to all the embodiments will be described with reference to FIG. The cylinder block 12 and the cylinder head 10 are
, The shim 15 protrudes from the gasket surface, and a moment M is generated around the shim 15. This moment M is the product of the bolt force F and the distance D between the center of the bolt and the center of the shim width. By moving the shim 15 away from the bore 12 near the head bolt 11, that is, by bringing the shim 15 closer to the head bolt 11, D becomes smaller and M becomes smaller. Therefore, when the moment M is transmitted to the bore wall 16 via the upper deck 13 and causes the bore deformation, M is small near the head bolt and M is large in the middle part of the head bolt, so that the moment M is uniform over the entire circumference. Try to make it. For this reason, the bore deformation is made uniform as shown in the right part of FIG. 11, and the conventional flower shape deformation is suppressed.

Next, the operation unique to each embodiment will be described. In the first embodiment, since the cross-sectional shape of the shim 15 is constant over the entire circumference, the shape and dimensions are stable, and there is little influence of manufacturing errors. Therefore, it suffices to punch a plate having a uniform thickness from a plate having a uniform thickness, and there is little variation between products. As a result, stable flower shape suppression of the bore can be achieved.

In the second embodiment, since the center of the width of the outermost peripheral shim 15 is displaced from a perfect circle to a direction approaching a square,
The operation according to the embodiment is obtained. Further, in the second embodiment, not only the center in the width direction of the outermost peripheral shim 15 is shifted from the perfect circle, but also the thickness of the shim is changed in the circumferential direction so that the thickness is thin near the head bolt and thick in the middle part of the head bolt. 4, the magnitude of the moment M generated at the position of 45 ° with the outermost peripheral shim 15 as a fulcrum can be reduced, and uniformization of the moment M in the circumferential direction is promoted. Further, in the second embodiment, the thickness of the outermost peripheral shim 15 is changed in the width direction,
Since the taper is made thinner toward the outer peripheral side, the cylinder head 1 when clamped with the head bolt 11 as shown in FIG.
The upper surface and the lower surface of the shim 15 can adhere to the surfaces of the cylinder head 10 and the cylinder block 12, thereby improving the sealing performance.

In the third embodiment, the grommet 27 is used for the sealing portion.
By changing the width of the grommet 27, suppression of flower-shaped deformation of the bore hole is achieved. Because it uses grommet without special shim,
This can contribute to cost reduction as compared with the case where the number of shims is increased.

In the fourth embodiment, the sealing portion is a wiring 2
8, the shape of the wiring 28 is changed from a round shape to a shape close to a square shape, thereby suppressing the flower-shaped deformation of the bore hole. Since the conventional wiring is used by changing its shape, the cost can be reduced as compared with the case where the number of shims is increased.

In the fifth embodiment, the seal portion is formed from the bead 29, and the bead 29 is formed into a shape that approaches a quadrangle from a round shape, thereby suppressing the flower-shaped deformation of the bore hole. Since only the bead shape is changed, the cost can be reduced as compared with the case where the number of shims is increased.

[0021]

According to the head gasket of any one of the first to fifth aspects, the moment can be made uniform in the circumferential direction, and the flower shape deformation of the cylinder bore can be suppressed. In addition, it is not necessary to increase the number of shims for preventing cylinder bore deformation, so that an increase in cost can be prevented. According to the head gasket of the second aspect, in addition to the above-described effects, an effect that the adhesion to the opposing surface of the outermost peripheral shim is improved and the sealing property can be improved can be obtained.

[Brief description of the drawings]

FIG. 1 is a partial plan view of a cylinder head gasket according to a first embodiment of the present invention.

FIG. 2 is a partial plan view of a cylinder block to which the head gasket of FIG. 1 is mounted.

FIG. 3 is a sectional view taken along line 3-3 in FIG. 2;

FIG. 4 is a partial plan view of a cylinder head gasket according to a second embodiment of the present invention.

FIG. 5 is a sectional view taken along line 5-5 in FIG. 4;

FIG. 6 is a sectional view taken along line 6-6 in FIG. 4;

FIG. 7 shows a cylinder block using the head gasket of FIG. 4;
FIG. 3 is a partial cross-sectional view when fastening between cylinder heads.

FIG. 8 is a partial plan view of a cylinder head gasket according to a third embodiment of the present invention, and a sectional view taken along lines AA and BB.

FIG. 9 is a partial plan view of a cylinder head gasket according to a fourth embodiment of the present invention, and a sectional view taken along lines AA and BB.

FIG. 10 is a partial plan view of a cylinder head gasket according to a fifth embodiment of the present invention, and a sectional view taken along lines AA and BB.

FIG. 11 is a plan view of a cylinder block showing a flower shape deformation of a cylinder bore and a state in which the flower shape deformation is suppressed.

FIG. 12 is a plan view of a conventional cylinder head gasket.

FIG. 13 is a cross-sectional view of a cylinder block showing deformation that occurs in the cylinder block when a conventional head gasket is mounted.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Cylinder head 11 Head bolt 12 Cylinder block 13 Upper deck 14 Cylinder head gasket 15 Shim (seal part) 16 Bore wall 17 Near head bolt part 18 Head bolt middle part 19 Bolt boss part 20 Cylinder bore 23 Gasket bore hole 24 Gasket bolt hole 25 Inner circumference shim 26 Bead 27 Grommet 28 Wiring 29 Bead

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F16J 15/00-15/14 F02F 11/00

Claims (2)

(57) [Claims] 1. A cylinder head gasket having an opening for a cylinder bore and having at least a single sealing portion around the opening, wherein the position of the sealing portion is far from the cylinder bore when the center in the width direction of the sealing portion is near the cylinder head bolt. A cylinder head gasket characterized by being set so as to be close to a cylinder bore between head bolts. 2. The cylinder head gasket according to claim 1, wherein said seal portion is made of a shim whose thickness becomes smaller toward the outer peripheral side, and further has a seal portion on an inner periphery of said seal portion.