JP2973099B2 - 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 an improvement in a head gasket having a two-piece bead having enhanced gas sealing performance and used for a head gasket of an internal combustion engine.

[0002]

2. Description of the Related Art A head gasket 10 for sealing between a cylinder head of an internal combustion engine and a cylinder block 11 as shown in FIG. 5 has a planar shape as shown in FIG. It is necessary to generate a sufficient sealing surface pressure in order to seal the combustion gas generated, the lubricating oil circulating in the oil gallery, the cooling water in the water jacket 22, and the like. In particular, since it is necessary to seal a high-temperature and high-pressure combustion gas at the peripheral portion of the combustion chamber 21, a metal gasket excellent in mechanical strength and durability has been conventionally used.

In such a metallic head gasket, if a single-plate gasket having only one metal substrate is used, in order to maintain the rigidity and durability of the gasket as a whole, a relatively rigid hard plate such as a stainless spring plate is used. Since a strong metal plate is used, there is a problem that the adaptability to the contact surface on the engine side is relatively poor, and it is difficult to adjust the surface pressure of the seal portion and to prevent the flattening of the bead.

For this reason, a head gasket having a two-layer structure is used in which a sub-plate 4 made of a relatively soft and easy-to-use material such as a stainless steel annealing plate is laminated on a metal substrate 1 as shown in FIG. In addition, the compatibility with the contact surface on the engine side, the adjustment of the seal surface pressure and the problem of bead protection have been improved.

In such a two-piece head gasket, a folded portion 4c is provided on the peripheral edge of the combustion chamber hole 2,
Along with the sub-plate 4 on which the substrate 1 is laminated, it is bulged to one side to form a loop-shaped bead 3 to generate a high sealing surface pressure, thereby improving the performance of the gasket. In order to seal the bolt hole 7, the cooling water hole 2a, and the oil hole 2b through which the head bolt penetrates, a sub-bead (seal ring) 6 is provided in the peripheral portion thereof.

FIG. 3 shows a specific example of the head gasket having the two-piece structure. In this head gasket, a bead 3 is provided so that the side where the sub-plate 4 is provided at the peripheral edge of the combustion chamber hole 2 becomes a concave portion. The bead 3 improves the sealing performance, and the folded portion 4a of the sub-plate 4 , Bead 3
To prevent abnormal flattening.

As shown in FIG. 3A, when the sub-plate 4 is provided on the cylinder block 11 side, that is, when the bulging portion of the bead 3 and the substrate 1 are provided on the cylinder head 12 side, FIG. Compared to the case where the sub-plate 4 side is provided on the cylinder head 12 side shown in b), when the pressing force F on the upper surface of the cylinder liner 11a acts, the pressed portion can be made wider across the bead 3. The inner and outer peripheries of the bead 3 can be pressed substantially uniformly and widely. Therefore, the deformation of the cylinder liner 11a can be suppressed, and the amount of bore deformation can be reduced. A schematic distribution state of the surface pressure p at this time is shown below (a) and (b) of FIG.

When the head gasket 10 is sandwiched between the cylinder block 11 and the cylinder head 12, the sealing surface pressure generated by the fastening force of the head bolts provides sufficient sealing performance over a long period of time. Care is taken to be within a range suitable for holding, and these head bolts are tightened with a torque wrench according to a predetermined order to a predetermined tightening torque, so that the tightening torque is uniform. Assembled.

[0009] This is because if the sealing surface pressure generated by the bolt fastening force is too weak, the function of sealing the combustion gas or the like cannot be sufficiently performed. This is because this may cause breakage or sagging of the part, making it impossible to maintain the sealing performance for a long period of time.

[0010]

However, in the conventional two-piece head gasket 20 shown in FIG. 4, since the material of the substrate 1 and the material of the sub-plate 4 in contact therewith are different, the thermal expansion Since the sub-plates 4 are more likely to thermally expand than the substrate 1 due to the difference in the rates, a thermal stress is generated that causes the laminated substrate 1 and the sub-plates 4 to bend like a bimetal. When the head gasket 20 is warped and deformed due to this thermal stress, the sealing portion is distorted, so that there is a problem that the sealing performance is reduced.

Further, a displacement occurs between the substrate 1 and the sub-plate 4 due to a difference in thermal expansion, so that the substrate 1 and the sub-plate 4 rub against each other, and also rub against the contact surface on the engine side. There is a problem of lowering. Among them, the rubbing amount is particularly large in the sub-plate 4 having a large thermal expansion, and thus there is a problem that the durability of the sub-plate 4 is particularly lowered.

When the sub-plate 4 is located on the side of the open deck type cylinder block 11, the deformation due to the difference in thermal expansion appears as a droop B of the sub-plate 4 at the portion facing the water jacket 22. That is, the thin and flexible sub-plate 4 on the surface on the cylinder block 11 side is susceptible to heat, and the portion facing the water jacket 22 has no contact surface that regulates the thermal expansion of the sub-plate 4.
Since the swelling deformation of the sub-plate 4 cannot be prevented, the sagging B of the sub-plate 4 occurs.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a head gasket capable of preventing thermal deformation of a subplate and a substrate of a two-piece head gasket and improving durability and sealing performance. Things.

[0014]

In order to achieve the above object, a head gasket according to the present invention has a combustion chamber hole opened in a substrate of a head gasket used in an internal combustion engine, and the periphery of the combustion chamber hole is folded back. A sub-plate surrounded by a section is laminated on the substrate and provided in a portion of the sub-plate which is not pressed by the cylinder block, a hollow hole, a slit, and a number of small holes are formed.
It is formed by providing a stress relaxation portion formed by at least one of the perforated zones .

The portion of the sub-plate not pressed by the cylinder block is, for example, the portion of the sub-plate facing the water jacket. The stress relieving portion is a portion that reduces the thermal stress generated in the sub-plate and reduces the effect of the thermal stress on the substrate, and is formed by a hollow band, a slit, a porous zone having a number of small holes, or the like. .

Therefore, according to the head gasket of the present invention, the provision of the stress relieving portion absorbs the elongation of the sub-plate, thereby reducing the thermal stress generated in the sub-plate. Since the amount of warping deformation of the head gasket can be reduced, the amount of deviation between the sub-plate and the substrate and the contact surface on the engine side due to thermal expansion can be reduced.

Further, a bead is provided on the periphery of the combustion chamber hole so that the side where the sub-plate is provided becomes a concave portion, thereby improving the sealing performance. The sub-plate is provided on the side that comes into contact with the cylinder block, so that the pressing surface is made wider.

[0018]

Next, an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, a head gasket 10 according to the present invention is a two-piece head gasket 10 used for an internal combustion engine, and has a combustion chamber hole 2 in a substrate 1 corresponding to a combustion chamber 21 of a cylinder block 11.
And a single sub-plate 4 that surrounds the combustion chamber hole 2 with the folded portion 4 c is provided on the substrate 1.

Further, a bead 3 is provided on the periphery of the combustion chamber hole 2 so that the side where the sub-plate 4 is provided becomes a concave portion. The bead 3 is configured to have a bead 3 provided on a laminated plate and having both the substrate 1 and the sub-plate 4 in close contact with each other. Further, sub-beads (seal rings) 6 for water and oil holes are formed on the substrate 1 at peripheral portions located at both ends of the head gasket 10.

The portion of the sub-plate 4 not pressed by the cylinder block, for example, the water jacket 12
Is provided with a stress relaxation portion 5 for relaxing thermal stress generated in the sub-plate 4. The stress relief portion 5 is formed by a hollow hole 5 provided in a portion facing the water jacket 12, and as shown in FIG. 1A, a portion extending from the center of the combustion chamber hole 2 to the head bolt hole 7. Avoid
The sub-plates 4 are arranged so as to maintain the connection of each part.

The stress relieving portion 5 is not limited to the hollow hole 5, but may be provided with a slit 5a in each part as shown in FIG. 2A, or a slit as shown in FIG. 5b in a staggered arrangement, or as shown in FIG.
As shown in (c), a porous zone 5c in which a number of small holes 15 are arranged may be provided. In short, it suffices if the thermal stress generated in the sub-plate 4 can be reduced to reduce the thermal deformation of the head gasket 10.

Note that the substrate 1 does not have this stress relaxation portion, and the substrate 1 forms a seal between the cylinder block 11 and the cylinder head 12. However, the substrate 1 is provided with a cooling water circulation hole 8 for supplying cooling water from the cylinder block 11 to the cylinder head 12, an oil circulation hole, and the like as necessary. The substrate 1 and the sub plate 4 of the head gasket 10 are formed of, for example, a stainless steel plate, an iron plate, a copper plate, an aluminum plate, or the like.
m and 0.08 to 0.20 mm.

The shape of the bead 3 and the thickness of the auxiliary plate 4 are changed in design by factors such as the pressure of the combustion gas to be sealed and the bore pitch which is the distance between adjacent cylinders. Adjust so that surface pressure and durability can be obtained.

The head gasket 10 is pressed and held between the cylinder block 11 and the cylinder head 12 by fasteners such as head bolts, and the beads 3 are crushed to form a seal portion. When the pressing force is further increased, the three-layered portion of the sub-plate 4 on the inner peripheral side of the bead 3 is placed between the upper surface of the cylinder liner 11a and the cylinder head 1.
Abut against the lower surface of the bead 2 to protect the bead 3 and prevent it from being completely flattened, while properly maintaining the seal surface pressure to ensure the seal. In addition, the sub-bead 6 is in close contact with the block outer wall 11b, and seals peripheral portions such as the bolt holes 7 and the cooling water holes 2a.

The head gasket 10 configured as described above
According to this, since the stress relaxation portion 5 is provided in a portion of the sub-plate 4 which is not pressed by the cylinder block, for example, a portion located on the water jacket 12, a difference in thermal expansion between the sub-plate 4 and the substrate 1 is caused. The generated stress on the sub-plate 4 side can be reduced, and the amount of deformation of the sub-plate 4 can be reduced. Further, in the portion pressed by the cylinder block, the sub-plate 4 portion without the stress relaxation portion 5 comes into contact with the cylinder liner 11a, the outer wall of the cylinder block, and the like, so that the sealing performance can be improved.

Therefore, since the influence of the difference in thermal expansion on the substrate 1 due to the laminated sub-plates 4 can be reduced, the stress and deformation generated on the substrate 1 can be reduced. for that reason,
Since the warping deformation due to the thermal load on both the sub-plate 4 and the substrate 1 can be reduced, not only the relative displacement between the sub-plate 4 and the substrate 1 but also the relative displacement between these and the engine-side contact surface can be reduced. The displacement and the amount of movement between the surfaces can be reduced. Therefore, the durability of the head gasket 10 can be improved.

[0027]

According to the head gasket of the present invention, in the head gasket having a two-piece structure , a cutout hole and a slit are formed in a portion of the sub-plate facing the water jacket.
G, formed in at least one of the porous zones with many small holes
It is provided with the made stress relieving portion, while maintaining the sealing performance due to the sub-plate at a portion in contact with the engine, since the sub-plate thermal stress generated by the difference in thermal expansion between the auxiliary plate and the substrate can be relaxed, sub The stress on the substrate side on which the plates are stacked can also be reduced, and the amount of thermal deformation can be reduced for both.

Accordingly, since the amount of warpage of the head gasket can be reduced and the amount of relative displacement from the engine side, that is, the amount of deviation, can be reduced, the sealing performance and durability of the head gasket can be improved.

[Brief description of the drawings]

FIGS. 1A and 1B are views showing a main part of a head gasket according to the present invention, wherein FIG. 1A is a partial plan view, and FIG.

FIG. 2 is an enlarged partial plan view showing another embodiment of the stress relaxation portion of the head gasket according to the present invention, wherein (a) is a single slit, (b) is a staggered slit, and (c) is porous. Each band is provided.

3A and 3B are diagrams showing a pressure distribution of a head gasket according to the related art, in which FIG. 3A is a partial longitudinal sectional view in which a sub plate is provided on a cylinder block side, and FIG. It is a partial longitudinal section.

FIG. 4 is a longitudinal sectional view of a main part of a head gasket according to the related art.

FIG. 5 is a perspective view showing an example of an open deck type cylinder block.

FIG. 6 is a plan view of a head gasket.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Board | substrate 2 ... Combustion chamber hole 3 ... Bead 4 ... Sub-plate 4c ... Folding part 5 ... Stress relaxation part 6 ... Sub-bead 7 ... Bolt hole 8 ... Cooling water circulation hole 10, 10a, 10b, 10c, 20, 30 ... Head gasket 11: Cylinder block 11a: Cylinder liner 11b: Block outer wall 12: Cylinder head 21: Combustion chamber (bore) 22: Cooling water jacket (W / J) 23: Bolt hole

Claims (4)

(57) [Claims] 1. A combustion chamber hole is opened in a substrate of a head gasket used in an internal combustion engine, and a single sub-plate surrounding the periphery of the combustion chamber hole with a folded portion is provided on the substrate in a stacked manner.
The pressed portion not in the cylinder block of the sub-plate, Ku
With a small number of perforated zones with punched holes, slits and many small holes
A head gasket formed with at least one stress relief portion. 2. The portion not pressed by the cylinder block is a portion facing a water jacket.
The described head gasket. 3. A bead is provided on the periphery of the combustion chamber hole such that a side on which the sub-plate is provided becomes a concave portion.
The head gasket described in 1. 4. The head gasket according to claim 1, wherein said sub-plate is provided on a side contacting a cylinder block.