JP2000220744A - Metallic gasket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To assure a sealing effect between a cylinder block and a cylinder head over a chain casing cover for a long term, and manufacture metallic gaskets in low costs by following to the difference of thermal expansion deformation of the cylinder block and the chain casing cover. SOLUTION: A metallic gasket 40 is composed of a sub plate 54, and an upper base plate 50 and a lower base plate 52 which consist of thin walled metal plates laminated on an upper part and a lower part of the sub plate, and is interposed between a cylinder block 2 and a chain casing cover 4 adjacent to each other and a cylinder head 70 avobe them. In this metallic gasket, a hole 60 formed on the sub plate at a position which rides on an upper part of a joining part 10 of the cylinder block and the chain easing cover, and a lower bead 58 which consists of a first cutout bead part 58a and a second cutout bead part 58b where upper parts of front edges are located to on an upper part of a joining part by folding diagonally to the upper part of the hole is formed on a position of the lower base plate corresponding to the hole. Furthermore, a sealant 74 having elasticity is arranged on a region surrounded with an upper surface of the cylinder block and the chain casing cover sandwiching the joining part and a lower part of the lower bead.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal gasket, and more particularly, to a metal gasket and a cylinder block cover made of dissimilar materials, which are interposed between a cylinder head and a cylinder head thereover, and which are suitably sealed. Metal gaskets that can be used.

[0002]

2. Description of the Related Art In general, a joint surface between a cylinder block constituting an engine for an automobile or other internal combustion engine and a cylinder head mounted thereon is provided with a fluid such as combustion gas, cooling water, lubricating oil or the like from the joint surface. Various gaskets are interposed to prevent leakage of the gasket. Conventionally, as such a gasket, a so-called soft gasket formed of an asbestos material, a chemical fiber, a carbon sheet material, or the like has been provided. However, heat resistance, compression resistance, and durability are rich.
Metal gaskets having good resilience (spring characteristics) and thermal conductivity have been widely used.

In recent years, with the rapid technological innovation of internal combustion engines, developments such as downsizing and lightening of engines, high output, and fuel saving have been advanced. For example, the number of valves has been reduced to two per cylinder per cylinder. On the other hand, the number of camshafts for operating this valve is increased from two to four,
By rotating the cam shaft at a high speed, it is possible to improve the suction efficiency and the exhaust efficiency.

Here, as a method for driving the camshaft to rotate, a belt driving method which is low in noise at the time of driving and does not require a refueling operation has been generally adopted. However, a timing belt used in the belt driving method is: In recent years, there has been a tendency to switch to a chain drive type engine because of poor durability against a high load and reduction in noise during driving due to improvement of the chain.

In the chain drive system, it is necessary to appropriately supply oil to the chain in order to maintain good drive. Therefore, in order to prevent oil scattering and to reduce noise during driving, the chain drive type engine has a cylinder block 2 and a chain case cover 4 for accommodating a camshaft drive chain, as shown in FIG. Is produced separately.

Usually, the cylinder block 2 is formed by casting using cast iron as a raw material, and the chain case cover 4 is formed by casting using aluminum as a raw material.
Is in contact with the side surface of the cylinder block 2 provided with the cylinder bore 6, and a lower portion of each is connected with a fastening bolt to form a space 8 for running the chain. Also, the upper surface 2a of the cylinder block 2 and the chain case cover 4,
After disposing a metal gasket on the cylinder head 4a and mounting the cylinder head, the cylinder block 2 and the chain case cover 4 are connected to the cylinder head by fastening bolts.

The aluminum chain case cover 4 is more greatly deformed by thermal expansion than the cast iron cylinder block 2, and the upper joint surface 4a of the chain case cover 4 is attached to the cylinder block 2 in consideration of the thermal expansion deformation. In some cases, it is set lower than the upper surface 2a.
Has a step 12 including a processing error.

As a result, a slight gap is formed between the step 12 of the joint 10 and the metal gasket, and a slight pressure fluctuation occurs in the chain case cover 4 and lubrication occurs as the chain runs for driving the camshaft. If oil such as oil is repelled, the oil may leak out of the gap to the outside of the chain case cover 4. Therefore, a metal gasket having a structure shown in FIGS. 7 and 8 is known as a metal gasket for embedding the step 12 of the joint 10.

The metal gasket 14 is a member in which three metal thin plates (the upper substrate 16 and the lower substrate 18 and the sub-plate 20 disposed between them) are laminated, and corresponds to the space 8 for running the chain. A chain opening hole 22 is provided. The upper substrate 16 and the lower substrate 18 of the metal gasket 14 are provided with beads 24, 2
6 are formed. And bead 2 of lower substrate 18
6, a punching hole 28 is formed at a position straddling the joint 10 between the cylinder block 2 and the chain case cover 4. A seal member 3 made of a rubber elastic body having a substantially trapezoidal cross section is provided on the lower surface of the sub plate 20 at a position straddling the joint portion 10.
0 is fixed in the mold and located in the punched hole 28.

When the metal gasket 14 is interposed between the cylinder block 2 and the upper surfaces 2a, 4a of the chain case cover 4 and the cylinder head, the beads 24, 26 are elastically deformed and the seals projecting downward from the punched holes 28 are formed. The member 30 fills the step 12 of the joint portion 10 while compressively deforming the cylinder block 2 and the chain case cover 4.
A gap between the metal gasket 14 and the metal gasket 14 is prevented.

[0011]

However, in the metal gasket 14, a small-sized sealing member 30 must be molded and fixed at a specific position on the sub-plate 20, and the operation requires a lot of labor and time. Therefore, the manufacturing cost of the metal gasket 14 may increase. Further, when the step 12 becomes zero due to a temperature rise when the engine is driven, the seal member 30 may be excessively compressed and deteriorate early.

The present invention has been made in view of the above circumstances, and is provided between a cylinder block and a chain case cover made of dissimilar materials and a cylinder head above them to form a cylinder block and a chain case cover. And a metal gasket with a low manufacturing cost while guaranteeing a long-term sealing effect between the cylinder block and the chain case cover and the cylinder head thereon. The purpose is.

[0013]

According to a first aspect of the present invention, there is provided a metal gasket comprising a metal sub-plate and an elastically deformable metal plate thinner than the sub-plate. An upper substrate and a lower substrate laminated on the upper and lower portions of the sub-plate, the cylinder block and the chain case cover interposed between adjacent cylinder blocks and chain case covers and the cylinder head thereon. In the metal gasket for sealing between the cylinder heads, a hole is formed in the sub-plate at a position straddling an upper part of a joint portion of the cylinder block and the chain case cover, and a position of the lower substrate corresponding to the hole is provided. A first notched bead portion bent obliquely upward from the cylinder block side and having an upper end located above the joint portion; The lower end bead is bent obliquely upward from the case cover side to form a lower bead including a second notched bead portion having an upper end located above the joint portion, and the cylinder block and the cylinder block sandwiching the joint portion. An elastic sealant was provided in a region surrounded by the upper surface of the chain case cover and the lower portion of the lower bead.

According to a second aspect of the present invention, in the metal gasket according to the first aspect, an upper end of the first notch bead and an upper end of the second notch bead are provided.
The bent portion was formed such that the tip pointed horizontally or diagonally downward. Further, the invention according to claim 3 is the metal gasket according to claim 1 or 2, wherein the upper substrate has
An upper bead was formed at a position straddling the joint between the cylinder block and the chain case cover.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. The same components as those shown in FIG. 6 are denoted by the same reference numerals, and description thereof will be omitted. FIG.
The metal gasket 40 of the present embodiment shown in FIG. 1 has a cylinder bore 42 corresponding to the cylinder bore 6 of the cylinder block 2.
A bolt hole 44 corresponding to an arrangement position of a fastening bolt connecting the cylinder block 2 and the cylinder head; a chain opening hole 46 corresponding to an upper opening of the space 8 for running the chain; This is a gasket provided with a bolt hole 48 adjusted to a position where a fastening bolt for coupling to a cylinder head is provided.

The metal gasket 40 includes an upper substrate 50 and a lower substrate 52 made of a thin metal plate,
And a metal sub-plate 54 disposed between the lower substrate 52 and the lower substrate 52. As shown in FIGS. 1 and 2, the upper substrate 50 has a first opening along the chain opening hole 46.
In some cases, the upper bead 56a is formed, and the second upper bead 56b is formed at a position straddling the joint 10 between the cylinder block 2 and the chain case cover 4.

The second upper bead 56 of the upper substrate 50
A punching hole 60 is formed at a position straddling the joint portion 10 of the sub-plate 54 corresponding to “b”, and the lower substrate 52 is formed by cutting out a position corresponding to the punching hole 60 of the sub-plate A bead 58 is formed. As shown in FIG. 3, the lower bead 58 of the lower substrate 52
The two notches are formed in parallel with each other so as to cross 0, and cut between the two notches along the joint portion 10, thereby forming two notch bead portions 58a. ,
58b. Then, as shown in FIG. 2, one of the notched bead portions 58a is bent obliquely upward, and the other notched bead portion 58b is also bent obliquely upward to form the lower portion 58. Here, the bend portions 58a are provided on the tip sides of the notched bead portions 58a and 58b such that their tips face horizontally or diagonally downward.
₁ and 58b ₁ are formed.

The metal gasket 40 of the present embodiment is
In order to assemble, the punched hole 60 is positioned below the first upper bead 56b, and the lower bead 5 is positioned below the punched hole 60.
The upper substrate 50, the lower substrate 52, and the sub-plate 54 are fixed in layers so that 8 is located. According to the metal gasket 40 having such a structure, there is no need to fix the seal member to the sub-plate as in the conventional metal gasket shown in FIG.
Metal gasket 4 in a short time with a small number of assembly steps
0 is completed, the metal gasket 40
Can greatly reduce the manufacturing cost.

FIG. 4 shows the arrangement of the metal gasket 40 interposed between the cylinder block 2 and the chain case cover 4 and the cylinder head 70 when the engine is stopped. The reference numeral 72 in this figure is
This is an end face gasket that prevents poor joining due to surface irregularities on the joining end face of the cylinder block 2 and the chain case cover 4. When this end face gasket 72 protrudes above the upper surface 2a of the cylinder block 2 and the upper joint surface 4a of the chain case cover 4a, when the cylinder head 70 is joined onto the adjacent cylinder block 2 and the chain case cover 4, In addition, since the protruding portion is bent and the precise bonding state is impaired, the upper surfaces 2a, 4a
It is assembled so as to be lower than a.

In the present embodiment, a soft elastic sealant 74 is disposed at a position surrounded by the upper surface 2a, 4a of the cylinder block 2 and the chain case cover 4 and the lower bead 58 of the lower substrate 52 with the step 12 therebetween. Has been established. As the soft elastic sealant 74, for example, FIPG (Fo
A liquid gasket called "rmed In Place Gasket" is used.

In FIG. 4, since the chain case cover 4 is in a low temperature state, a large step 12 occurs at the joint 10 between the cylinder block 2 and the chain case cover 4. At this time, the soft elastic sealant 74 disposed on the step 12 is pressed by the downward elastic restoring force of the lower bead 58 deformed toward the punched hole 60 of the sub-plate 54, and is elastically compressed. The area sandwiching is embedded. Here, the notched bead portions 58a and 58b forming the lower bead 58 have bent portions 58a ₁ and 5a
8b ₁ are formed, but the bent portions 58a ₁ , 58a
Since b ₁ also exerts an elastic restoring force downward, the soft elastic sealant 74 is locally pressed toward the step 12. In this way, the soft elastic sealant 74 is elastically compressed while the step 1
2, the gap between the cylinder block 2 and the chain case cover 4 and the cylinder head 70 is reliably prevented.

FIG. 5 shows the shape of the metal gasket 40 when the engine is driven. Since the chain case cover 4 is in a high temperature state and is thermally expanded and deformed,
The height of the joint 10 between the cylinder block 2 and the chain case cover 4 is substantially the same, and the step 12 is eliminated. At this time, the lower bead 58 is further deformed upward in the punched hole 60 of the sub-plate 54 while maintaining the optimum elastic compression state with respect to the soft elastic sealant 74. Thus, even if the step 12 is eliminated, the soft elastic sealant 74
Since the volume hardly changes and hardens, it is possible to reliably prevent the occurrence of a gap and to prevent early deterioration due to an excessively compressed state.

Therefore, the metal gasket 40 of the present embodiment is soft even if the step 12 of the joint 10 between the cylinder block 2 and the chain case cover 4 becomes large or the step 12 disappears due to the influence of heat. Since the generation of a gap is prevented in a state where the elastic sealant 74 is optimally elastically compressed, a good sealing state can be maintained. Also, if the elastic compressibility of the soft elastic sealant 74 decreases, the cylinder block 2 and the chain case cover 4
Upper bead 56 formed at a position straddling the joining portion 10
b exerts its own elastic restoring force on the soft elastic sealant 74 via the auxiliary plate 54 and the lower bead 58 of the lower substrate 52,
Since the optimum elastic compression ratio is given to the soft elastic sealant 74, a good sealing state can be maintained for a long period of time.

[0024]

As described above, according to the metal gasket of the first aspect, the cylinder block is positioned at a position corresponding to the hole of the sub-plate formed at a position straddling the upper part of the joint between the cylinder block and the chain case cover. Forming a lower bead consisting of a first notched bead portion bent obliquely upward from the side and a second notched bead portion bent obliquely upward from the chain case cover side, and a cylinder block sandwiching the joint portion; Since an elastic sealant is provided in the area surrounded by the upper surface of the chain case cover and the lower part of the lower bead, the presence or absence of a step at the joint between the cylinder block and the chain case cover is affected by the influence of heat. The sealing agent pressed downward by the elastic restoring force of the lower bead deforms flexibly and elastically, causing a gap at the joint. It can be always maintained satisfactory sealing state without.

Further, since the operation of fixing the seal member to the sub-plate as in the prior art is eliminated, the upper substrate, the sub-plate and the lower substrate can be simply fixed in layers in a short time.
The manufacturing cost of the metal gasket can be significantly reduced. According to the second aspect of the present invention, the effect of the first aspect can be obtained, and the top end of the first notch bead and the top end of the second notch bead are horizontal. Since the bent portions are formed so as to face in the direction or diagonally downward, the sealant is locally pressed toward the joint portion by the elastic restoring force generated in these bent portions. As a result, when a step occurs,
Since the sealing agent comes into close contact with the step, a more favorable sealing state can be maintained.

Further, according to the third aspect of the invention, the effect of the first or second aspect can be obtained,
Even if the elastic compressibility of the deformed sealant is reduced, the upper bead provided at the position straddling the joint between the cylinder block and the chain case cover of the upper substrate is caused by its own elastic restoring force. Since the optimum elastic compression ratio is given by pressing the sealant, a good sealing state can be maintained for a long time.

[Brief description of the drawings]

FIG. 1 is a main part plan view showing a metal gasket of the present invention.

FIG. 2 is a view taken along the line II-II in FIG.

FIG. 3 is a plan view showing a main part of a lower substrate according to the present invention.

FIG. 4 is a diagram showing a sealing state of a metal gasket when a step is generated at a joint between a cylinder block and a chain case cover.

FIG. 5 is a diagram showing a sealing state of a metal gasket when no step is formed at a joint between a cylinder block and a chain case cover.

FIG. 6 is a perspective view showing a joined state of a cylinder block and a chain case cover.

FIG. 7 is a plan view of a main part showing a conventional metal gasket.

FIG. 8 is a view taken along line XIII-XIII in FIG. 7;

[Explanation of symbols]

2 Cylinder block 4 Chain case cover 10 Joint 12 Step 40 Metal gasket 50 Upper board 52 Lower board 54 Sub-board 56b Second upper bead (upper bead) 58 Lower bead 58a Notch bead (first notch bead) 58a ₁ , 58b ₁ bent portion 58b notched bead portion (second notched bead portion) 60 punching hole (hole) 74 soft elastic sealant (sealant) 70 cylinder head

Claims (3)

[Claims] 1. A sub-plate made of a metal, and an upper substrate and a lower substrate laminated as upper and lower portions of the sub-plate as an elastically deformable metal plate thinner than the sub-plate. A metal gasket interposed between a chain case cover and a cylinder head thereon to seal between the cylinder block and the chain case cover and the cylinder head, wherein the sub-plate includes the cylinder block and the chain case cover A hole is formed at a position straddling the upper part of the joint, and the first substrate is bent obliquely upward from the cylinder block side at the position of the lower substrate corresponding to the hole so that the upper end is located above the joint. The notch bead portion and the chain case cover are bent obliquely upward from the side so that the top end is located above the joint portion. A lower bead including a second notched bead portion is formed, and a region surrounded by the upper surface of the cylinder block and the chain case cover and the lower portion of the lower bead sandwiching the joint portion has elasticity. A metal gasket comprising a sealing agent. 2. A bent portion is formed at the upper end of the first notched bead and at the upper end of the second notched bead so that the tip is directed horizontally or obliquely downward. The metal gasket according to claim 1, wherein 3. The metal gasket according to claim 1, wherein an upper bead is formed on the upper substrate at a position straddling a joint between the cylinder block and the chain case cover.