JP3083958B2 - Exhaust manifold gasket - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is applied to an exhaust passage of an internal combustion engine. The present invention is used for connection between an internal combustion engine and an exhaust pipe. Although the present invention has been developed for use in an automobile diesel engine, it can also be used in other exhaust passages of an internal combustion engine.

[0002] The present invention relates to a method for manufacturing a manifold gasket used in an exhaust passage of an internal combustion engine.

[0003]

2. Description of the Related Art Conventionally, an exhaust manifold gasket used for connection between a head assembly of an internal combustion engine and an exhaust manifold is, as shown in FIG. A spacer 1, a seal plate 12 formed of a thin metal plate and superposed on both outer surfaces of the first spacer 1, and a seal plate 12 formed of a thin metal plate classified into a plurality of stages and superposed on each outer surface of the seal plate 12 The second spacer 3 is spot-welded while being sandwiched between the surface plates 4 and 5 formed of a thin metal plate, and is integrally formed so as to have a sectional shape shown in FIG. FIG. 2 and FIG. 3 show the front and rear surfaces in the state of being integrally formed.

The first spacer 1, the seal plate 12,
Each of the second spacer 3, the surface plates 4 and 5 has a rectangular opening 1a, 1a, 1b corresponding to the exhaust passage of the head assembly 11 and the exhaust manifold 14 shown in FIG.
2a, 3a, 4a, 5a and the through hole 1b of the bolt 13,
12b, 3b, 4b, and 5b are provided. Also,
Projections 4c and 5c for spot welding are formed inward on the surface plates 4 and 5, and the first spacer 1, the seal plate 12 and the second spacer 3
At positions corresponding to the projections 4c and 5c, through holes 1c,
12c and 3c are provided.

Further, a bead 12d having a trapezoidal cross section is formed on the seal plate 12. FIG. 8 is an enlarged view of the AA cross section and the BB cross section in FIG. 2. The bead 12 d is formed along the outer periphery of the opening 12 a, with the opening sides inward toward the first spacer 1. Are formed in the same shape over the entire circumference.

[0006] As shown in FIG. 4, the exhaust manifold gasket thus configured has a head assembly 11.
And an exhaust manifold 14 and fastened by bolts 13. At this time, a load is applied to the bead 12d by tightening, and elastic deformation occurs on both sides of the trapezoidal cross section. The drag exerted by the elastic deformation is applied to the flange surfaces of the head assembly 11 and the exhaust manifold 14 via the surface plates 4 and 5, and this serves as a sealing surface pressure to prevent the exhaust gas from leaking.

[0007] When a load is applied to the bead 12d, the first spacer 1 is provided on each seal plate 12d.
The second spacer 3 prevents the bead 12d from being crushed when a load is applied to the bead 12d and causing permanent deformation, and the required sealing surface pressure. The bead height H shown in FIG. 8 for setting the range of elastic deformation that gives

[0008] In the conventional manufacturing method, the seal plate 12, which applies the sealing surface pressure to the surface plates 4 and 5 by the elastic deformation of the bead 12d, is subjected to a heat treatment before the bead 12d is formed. And
The bead 12d was formed after the predetermined hardness was given. This is because a long material before punching was more convenient for quenching than a punched small plate.

[0009]

As described above, the exhaust manifold gasket is interposed between the exhaust manifold and the head assembly and is fastened by a plurality of bolts.
Uneven surface pressure due to the effects of bolt arrangement and flange rigidity, and even when a uniform sealing surface pressure is applied during installation, the unit is subjected to a long-term tightening load under the influence of exhaust gas heat. Then, the flange surface of the exhaust manifold bends, and the sealing surface pressure becomes uneven.

As described above, conventionally, a seal plate is heat-treated in a raw material state, and a bead is formed after a required hardness is given by this heat treatment. When the hardness is increased, cracks are formed at the time of bead formation, and when the hardness is reduced in order to avoid the generation of the cracks, there is a problem that it is difficult to obtain required spring characteristics. Also, when the cross-sectional shape of the bead is formed by deep drawing, cracks occur if the hardness is high, and if the bead is formed by shallow drawing to avoid this, the required spring characteristics cannot be obtained. There were also restrictions on the bead shape.

The present invention has been made under such a background, and maintains a uniform sealing surface pressure for a long period of time even if the arrangement of the tightening bolts is uneven or the flange rigidity varies. It is another object of the present invention to prevent the exhaust gas from leaking.

Further, the present invention provides a bead having a cross-sectional shape intended by design, and a heat treatment is performed so as to have a hardness at which the most effective spring characteristics can be obtained. It is an object of the present invention to provide a method of manufacturing a gasket that can prevent leakage of gas.

[0013]

SUMMARY OF THE INVENTION A first aspect of the present invention is as follows.
The present invention relates to a gasket used for connection with an exhaust passage of an internal combustion engine and for connection between exhaust passage portions, and a bead formed of a thin metal plate is formed around an opening for the exhaust passage to deform against the sealing surface pressure. In the exhaust manifold gasket provided with the sealing plate and a pair of surface plates sandwiching the sealing plate, the opening is substantially rectangular, and corresponds to the vertical side and the horizontal side of the rectangle, respectively. The cross-sectional shape of the bead is different in the portion, the bead is formed in a continuous curve in a portion corresponding to the vicinity of the intersection of the vertical side and the horizontal side, the cross-sectional shape of the bead in the curved portion is continuously It is characterized by changing. Comprising two sealing plates,
A spacer can be sandwiched between the two seal plates.

A second aspect of the present invention relates to a method of manufacturing an exhaust manifold gasket used for an exhaust passage of an internal combustion engine, and the method is provided around an exhaust passage opening formed of a thin metal plate having high hardness. In a method for manufacturing an exhaust manifold gasket including a seal plate on which a bead deforming against a sealing surface pressure is formed, after forming the bead on a metal plate, the seal plate may have a predetermined hardness. It is characterized by performing a heat treatment. In the step of forming the bead, the metal plate is preferably in a state before a heat treatment.

[0015]

The sectional shape of the bead formed along the periphery of the exhaust passage opening of the seal plate is different between the P portion and the Q portion shown in FIG. 2, and the bead is connected by a continuously changing curve. I do. That is, the cross-sectional shape of the bead corresponding to the Q portion has a steep trapezoidal gradient, and the cross-sectional shape of the bead corresponding to the P portion has a gentle trapezoidal gradient.

By making the shape of the bead in this manner, a large resistance is given to a place where the flange rigidity is low or a place where the flange is likely to bend, and even if the bending due to the thermal effect is generated, it is sufficient to compensate for it. It is possible to obtain a sealing surface pressure, and it is difficult for the flange to bend at a portion where the flange rigidity is high, so that a sufficient level of sealing surface pressure can be obtained by applying a conventional level of drag.

As a result, even if the bolt arrangement is not uniform or the flange rigidity varies, the required sealing surface pressure can be obtained uniformly over the entire circumference, and partial leakage of exhaust gas occurs. Can be prevented.

In order to manufacture the exhaust manifold gasket, a bead is formed in a low hardness state before heat treatment is applied to a seal plate constituting the gasket.
Heat treatment is performed after this forming process. By performing bead forming while the material is in a soft state,
There is no crack generated at the time of forming process, so that the cross-sectional shape of the bead can be made into a shape formed by deep drawing, and furthermore, since heat treatment is performed after forming, there is no restriction for post-processing, and the most effective Heat treatment can be performed so as to obtain excellent spring characteristics.

As a result, the durability of the bead is enhanced, and leakage of exhaust gas can be prevented for a long period of time.

[0020]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view showing the configuration of the embodiment of the present invention, and FIG.
Is a front view showing the assembled state of the embodiment of the present invention and the conventional example,
FIG. 3 is a rear view showing an assembled state of the embodiment of the present invention and the conventional example. FIG. 4 is a view showing a cross section of a gasket when the head assembly and the exhaust manifold are mounted in the embodiment of the present invention and the conventional example. FIG. 2) shows an embodiment of the present invention.
Is an enlarged cross-sectional view taken along the line AA shown in FIG.

The embodiment of the present invention is similar to the conventional example described above.
First spacer 1 formed of a thin metal plate and located at the center
And a seal plate 2 formed of a thin metal plate and superimposed on both sides of the first spacer 1, and a seal metal plate formed of a thin metal plate classified into a plurality of stages and superimposed on the outer surface of each of the seal plates 2 The second spacer 3 is spot-welded while being sandwiched between the surface plates 4 and 5 formed of a thin metal plate, and integrally formed so as to have a cross-sectional shape shown in FIG. FIGS. 2 and 3 show the external shapes of the front and rear surfaces.

Each of the first spacer 1, the seal plate 2, the second spacer 3, and the surface plates 4 and 5 has a rectangular opening 1a corresponding to the exhaust passage of the head assembly 11 and the exhaust manifold 14 shown in FIG. , 2
a, 3a, 4a, 5a and through holes 1b, 2
b, 3b, 4b, and 5b. Also, projections 4c and 5c for spot welding are formed on the surface plates 4 and 5 inward, and the first spacers 1,
The seal plate 2 and the second spacer 3 are provided with through holes 1c, 2c and 3c at positions corresponding to the projections 4c and 5c.
d is formed.

A feature of the present invention is that, as shown in FIG. 5, the cross-sectional shape of the bead 2d is formed to be partially different depending on the distribution of the seal surface pressure. That is, as shown in FIG. 5 (a), the cross-sectional shape of the bead 2d at the portion P shown in FIG. In the cross-sectional shape, as shown in FIG. 5B, the rising of the bead 2d is sharp, and the slope of the trapezoidal cross-section is sharply formed. The four corners R are connected by curved surfaces whose sectional shapes change continuously. P, Q
Each of R and R is formed so that the height H from the outer surface of the second spacer 3 to the upper surface of the bead 2d is the same.

As shown in FIG. 4, the gasket having the above-described structure is combined with the head assembly 11 and the exhaust manifold 14.
When tightened with the bolt 13 interposed between
In a portion P where the amount of deflection of the flange surface of the exhaust manifold 14 is small, a sufficient sealing surface pressure can be obtained even with a small drag, and in a portion Q where the deflection of the flange surface is likely to be large, a large drag is given to the flange. Sufficient and uniform sealing surface pressure can be obtained by compensating for bending. Further, since the R portion connecting the P and Q portions is connected by a curved surface in which the cross-sectional shape of the bead 2d changes continuously, the drag generated by the elastic deformation as the portion moves from the P portion to the Q portion. Gradually increases, so that even at this R portion, a uniform sealing surface pressure can be obtained in consideration of a change in the amount of deflection of the flange.

FIG. 6 is a diagram showing the relationship between the load applied to the bead 2d by the tightening force and the resulting surface pressure. The relationship is shown when the bead 2d has a gentle cross-sectional shape, and when it is abrupt. Indicated by As described above, the surface pressure at the portion Q where the bead 2d having the steep gradient in cross section is used is set to a higher value than the portion P where the bead 2d having the gentle gradient is used.

The bead 2d formed on the seal plate 2 of the gasket thus configured is formed before the heat treatment, and the heat treatment is performed after the formation. By processing the seal plate 2 in such a process, since the material is still soft at the time of forming the bead 2, it is possible to avoid a crack due to the forming, and it is a deep drawing shape. Does not cause any problems.
In addition, since heat treatment is performed after forming into the shape intended by design, it is not necessary to set the hardness considering the forming process, and the hardness that can obtain the sealing surface pressure by the most effective spring characteristics Can be finished.

[0027]

As described above, according to the present invention, even if the bolt arrangement for fastening the flange of the exhaust manifold is uneven or the flange rigidity varies, the uniform tightening surface pressure over the entire circumference of the bead is obtained. Is obtained. Further, even if there is a temperature change or an aging change, the uniform surface pressure is always maintained because the elastic state is within a range where it can be restored.
As a result, there is an effect that it is possible to prevent a partial decrease in the sealing surface pressure due to the bending of the flange caused over time, and to prevent leakage of exhaust gas for a long period of time.

According to the manufacturing method of the present invention, the seal
The cross-sectional shape of the bead that is formed on the plate and gives a sealing surface pressure by being elastically deformed is intended by design, and the heat treatment can be performed so that the hardness is such that the most effective spring characteristics can be obtained. In addition, this method has the effect of increasing the durability of the bead and preventing the leakage of exhaust gas for a long period of time.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a configuration of an embodiment of the present invention.

FIG. 2 is a front view showing an assembled state of the embodiment of the present invention and a conventional example.

FIG. 3 is a rear view showing the assembled state of the embodiment of the present invention and the conventional example.

FIG. 4 is a diagram showing a cross section of the gasket when the head assembly and the exhaust manifold are mounted in the embodiment of the present invention and the conventional example.

FIG. 5 (a) is a cross-sectional view of the embodiment shown in FIG.
A sectional enlarged view, (b) is the BB sectional enlarged view.

FIG. 6 is a diagram showing a relationship between a load applied to a bead by tightening and a surface pressure in the present invention.

FIG. 7 is an exploded perspective view showing a configuration of a conventional example.

8A is an enlarged cross-sectional view taken along line AA of FIG. 2 in a conventional example, and FIG. 8B is an enlarged cross-sectional view taken along line BB of FIG.

[Explanation of symbols]

1 First spacers 1a, 2a, 3a, 4a, 5a, 12a Openings 1b, 2b, 2c, 3b, 3c, 4b, 4c, 5b, 5
c, 12b, 12c through hole 2, 12 seal plate 2d, 12d bead 3 second spacer 4, 5 surface plate 11 head assembly 13 bolt 14 exhaust manifold

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-88877 (JP, A) JP-A-5-42830 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16J 15/00-15/14 F01N 7/08 F02F 11/00

Claims (2)

(57) [Claims] 1. A seal plate formed of a thin metal plate and having a bead formed around an opening for an exhaust passage and deforming against the seal surface pressure, and a pair of surfaces sandwiching the seal plate in the exhaust manifold gasket and a plate, the opening I substantially rectangular der, short sides of the rectangle
The part of the bead has a gentle slope cross section,
The bead on the long side of the rectangle has a steep cross section.
There, wherein the bead is a short side and a portion corresponding to the vicinity of the intersection of the long side is formed in a curved continuous exhaust, wherein a cross sectional shape of the bead in its curved portion changes continuously Manifold gasket. 2. The exhaust manifold gasket according to claim 1, further comprising two seal plates, wherein a spacer is interposed between the two seal plates.