JPH0138285Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of a head gasket for an internal combustion engine, which is made of laminated metal thin plates. More specifically, by locating a folded part formed by folding back the tip of the face plate or intermediate plate so as to have a space in the vicinity of the combustion chamber sealing part formed by folding back the face plate, the back surface of the face plate can be closed. To provide a head gasket which can be pressed with a wide width to generate good sealing force.

[Conventional technology]

The head gasket, which is constructed by stacking several thin metal plates, is particularly important for gas sealing within the combustion chamber seal area (the area placed around the combustion chamber), and if this area is not sufficiently sealed, the inside of the combustion chamber may leak. This has the drawback that the gas leaks and the compression pressure decreases, which in turn leads to poor combustion conditions in the internal combustion engine.

Conventionally, a wiring type structure shown in FIG. 2 has been known as a structure for sealing the gas in the combustion chamber of a head gasket made of laminated metal sheets.

In this head gasket G, an intermediate layer consisting of intermediate plates 3a, 3b and 3c made of thin mild steel plates is laminated between an upper plate 1 forming a surface plate made of a thin stainless steel plate and a lower plate 2 made of a thin mild steel plate. has been done. The combustion chamber seal portion 5 formed to surround the combustion chamber hole 6 of the upper plate 1 has a cross section U.
A lower plate 2, which is bent into a shape and forms a surface plate at its tip, is positioned to hold intermediate plates 3a, 3b, and 3c therein. A wire ring 4 is provided as a reinforcing member inside the combustion chamber seal portion 5 formed by bending.

FIG. 3 is a cross-sectional view of the main part of a conventional bead-type head gasket, in which the tip of the upper plate 1, which is one surface plate, is bent to surround the combustion chamber hole 6 to form the combustion chamber seal part 5. Then, the tip thereof is positioned under the tip of the lower plate 2, which is the other surface plate, and the intermediate plates 3a, 3b,
3c is provided. In the metal plate laminated head gasket having this structure, a bead 7 is formed in a ring shape at the tip of the intermediate plate 3b.

Now, in the wiring type head gasket shown in FIG. 2, the cylinder liner 11 is inserted into the cylinder block 10 as shown in FIG. A head gasket G is mounted, and the upper surface of the head gasket G is pressed by a cylinder head 12.

When both sides of the wiring 4 are pressed by the cylinder head 12 and the cylinder liner 11 in this way, a strong surface pressure P ₁ (stress) is locally applied to parts a and b on both sides of the upper plate 1 located above and below the wiring 4. Occur.

Therefore, in an engine with a large tightening force such as a large engine, the portion a of the upper plate (covering plate) forming the combustion chamber seal portion 5, where the wiring ring 4 whose cross section is difficult to deform, is located. There were disadvantages in that cracks were likely to occur in b, there were problems with durability, and the sealing performance deteriorated easily. Further, the combustion chamber seal portion 5 is affected by the high temperature and high pressure gas within the combustion chamber, and has the disadvantage that sealing performance deteriorates early.

On the other hand, in the bead-type laminated metal plate head gasket shown in FIG. 3, the bead portion 7 connects the cylinder head 12 and cylinder liner 11 as shown in FIG.
This portion is deformed, and a surface pressure _P2 is generated accordingly. However, in a head gasket with this structure, it is not possible to obtain sufficient sealing surface pressure because the surface pressure is distributed over the entire bead, so the sealing performance is relatively poor. Therefore, in engines with low tightening force, gas There was a drawback that it was easy for the information to leak.

In addition, a bead was formed on one of the intermediate plates near the sealing part around the combustion chamber 6, and the
This is proposed by Publication No. 1174. However, the metal laminated gasket of this invention essentially has the structure shown in Fig. 3 of the invention, and when the bead is tightened, the bead weakens, and as shown in Fig. 5, the stress is dispersed and multiple There is a problem in that a mountain of surface pressure is formed, making it difficult to obtain a predetermined seal surface pressure.

Furthermore, Japanese Utility Model Application No. 55-55660 discloses a metal laminated gasket which has a two-layer structure by bending the circumference of the combustion chamber hole of a gasket made of a single metal plate and laminating the bent portion tightly. It has been proposed.

However, this single metal plate gasket forms a bag-shaped combustion chamber seal around the combustion chamber hole, and is bent to form a space at the end of the intermediate plate within this combustion chamber seal to provide elasticity. The present invention does not teach the technical idea of a metal plate laminated gasket, which is to securely seal while dispersing stress by sealing the gasket.

Another known technique is proposed in Japanese Patent Application Laid-Open No. 56-94064, which involves bending the surface plate around the combustion chamber hole into a circular cross-section, and forming a bead in the vicinity of this bent portion. This is configured to press the back surface of the tip of the top plate, which is an extension of the bent portion.

In the case of this head gasket, the bead is used to generate the surface pressure that exerts the sealing force, and the surface pressure similar to that shown in Fig. 4 is generated in that the elastic force of the bent portion is not used for the sealing force. It is difficult to obtain long-term sealing force.

[The problem that the idea aims to solve]

As mentioned above, the wire ring type head gasket has a problem in that strong local pressure is generated because the wire ring is hard and difficult to deform. In addition, bead-type head gaskets have the problem that a simple bead sets quickly and cannot provide sufficient surface pressure.

For these reasons, in conventional thin metal plate laminated head gaskets, those with a wiring structure are generally used in small engines, and those with a bead structure are generally used in large engines.

As described above, conventional thin metal plate laminated head gaskets have problems with the structure of the combustion chamber seal located around the combustion chamber, and have to be used separately for large or small engines, and can be used incorrectly. Problems occurred in sealing performance and durability.

The present invention was obtained in order to eliminate the drawbacks of the conventional head gasket, and includes:
The purpose is to provide a head gasket that can be used in both large and small engines.

[Means to solve the problem]

To achieve the above object, the present invention is a laminated structure consisting of a top plate made of two upper and lower thin metal plates, and an intermediate plate made of a plurality of thin plates sandwiched between these top plates, ) a folded part surrounding the combustion chamber hole is provided on one surface plate to form a combustion chamber sealing part; (b) a tip of the intermediate plate or the other surface plate is extended inside the folded part; (c) The part is folded back without forming a bead to form a teardrop-shaped space, and (c) the part is configured so that the elastic force of the folded part presses the back surface of the surface plate located near the combustion chamber seal part. This is a head gasket for internal combustion engines.

This space is particularly shaped like a teardrop, and is arranged in a ring shape in the folded part around the combustion chamber hole. It is pressed and deformed, but even when it is pressed to the maximum, a teardrop-shaped space remains slightly in the flattened state.

Therefore, the head gasket of the present invention does not generate local pressure fluid that would leave impressions on the cylinder head and cylinder liner, which are the parts to be sealed, and provides the necessary and sufficient surface pressure while making soft contact. This gives reliable sealing performance.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a plan view showing the main parts of the head gasket, in which a combustion chamber hole 6 is provided at a predetermined position in the head gasket G, and a folded part 5 of double structure is formed around this combustion chamber hole 6. A combustion chamber seal portion 9 is formed by a portion including this folded portion 5 and extending to the vicinity of the flange portion 11a (FIG. 4) of the cylinder liner 11.

In FIG. 1, reference numeral 14 indicates a bolt hole, 15 indicates a water hole, 16 indicates an oil hole, and 17 indicates a push rod hole.

FIG. 6 is a cross-sectional view of the main part of the head gasket showing the first embodiment of the present invention, in which a portion of the stainless steel upper plate 1 (surface plate) corresponding to the combustion chamber hole 6 is folded back to form a folded part 5. is formed, and its tip is located below the lower plate 2 (surface plate) made of mild steel. Intermediate plates 3a and 3b made of mild steel and an intermediate plate 3c thinner than these plates are laminated between the top plate 1 and the bottom plate 2.

The two intermediate plates 3a and 3c do not extend to the combustion chamber sealing portion 9, but one intermediate plate 3b extends to the vicinity of the folded portion 5 to form a bent portion 8.

This bent portion 8 has an important meaning in the present invention, and the intermediate plate 3b is not completely folded in half, but is particularly bent so that a teardrop-shaped space 20 is formed. It is being

As is clear from FIG. 6, this teardrop-shaped space 20 is intended to give a wide range of elasticity to the intermediate plate 3a, and the back surface of the upper plate 1 is pressed by the intermediate plate 3a. This generates a sealing force.

FIG. 7 shows a state in which the head gasket G according to the present invention is used in an engine. In this installed state of the head gasket G, the seal portion 9 is pressed by the flange portion 11a of the cylinder liner 11 and the cylinder head 12, with a pressing force acting particularly on the seal portion 9 having the bent portion 8. When the seal portion 9 is pressed in this manner, the bent portion 8 is pressed, the width of the teardrop-shaped space 20 is reduced, and stress _P3 is generated.

This stress P ₃ is generated by pressing the folded portion 8, that is, the seal portion 9, but since the teardrop-shaped space 20 is pressed so as to become flat, the fourth
Unlike the wiring type head gasket with stress _P1 in the figure, there is no steep stress, and a relatively gentle and wide stress curve is formed.

Therefore, the head gasket of the present invention has the advantages of the wiring structure gasket shown in FIG. 2 and the bead structure shown in FIG. There's nothing to do. In addition, unlike the bead type head gasket shown in Fig. 5, the stress is not dispersed, and the stress is obtained in a relatively high state within a wide range distributed within a certain range, so the sealing performance in the seal portion 9 is Very good.

More specifically, in the case of the stress P ₂ shown in FIG. 5, which is a conventional example, a fairly high stress occurs in the center, and low stress occurs on both sides thereof.

Furthermore, as shown in FIG. 4, if there is a portion where the stress _P1 is excessive, cracks tend to occur in the metal plates a and b on both sides of the wiring.

However, the head gasket of the present invention does not suffer from such drawbacks.

Furthermore, in the case of the bead structure shown in FIGS. 3 and 5, the stress other than the stress in the part where the bead 7 is provided is extremely low, but in the head gasket according to the present invention, the stress in the part where the bead 7 is provided is extremely low. As shown in Figure 7, a sufficient stress _P3 can be obtained within a certain range.

In the state shown in FIG. 7, the bent portion 8 of the intermediate plate 3b
The width of the teardrop-shaped space 20 provided in the engine is reduced by the pressing force when the gasket is attached to the engine. Sufficient tightening stress can be obtained over a wide range by the reaction force.

As shown in the above embodiment, when manufacturing the head gasket according to the present invention, the intermediate plates 3a, 3
b, 3c, it is necessary to form the bent portion 8 in a ring shape around the combustion chamber hole 6 so as to form a teardrop-shaped space 20 at the tip of the upper plate 1 or the lower plate 2.

This bent part 8 has a structure particularly adopted in the present invention, and it is important that it is located near the folded part 5 formed by bending one of the surface plates and on the back side of the combustion chamber seal part 5. It is.

Furthermore, by forming a special shape, that is, a teardrop-shaped space 20, in this bent portion 8, elasticity is imparted, which in turn imparts elasticity to a wide range of combustion chamber seal portions 9. .

[Effect of idea]

Since the present invention is configured as described above, the following effects can be achieved.

(1) Fold back around the combustion chamber hole to form an annular, bag-shaped combustion chamber seal, and use the inner surface of this seal as an intermediate plate or the end of the surface plate as a teardrop-shaped (elongated triangular) space. Since this folded part supports the inner surface (back surface) of the combustion chamber sealing part, elasticity is maintained in this folded part over a wide width. It will hit the seal.

(2) Therefore, as shown in FIG. 7, a relatively large stress spreads over a wide area, for example, the area of the flange 11a of the cylinder liner 11, and as a result, reliable sealing can be achieved and the conventional head gasket It has excellent durability and does not have the disadvantage of being easily damaged due to strong localized stress.

(3) By arranging the folded part having a teardrop-shaped space in the folded part formed on the surface plate as described above, the head gasket can be locally No impressions are formed on the cylinder head due to strong pressing force.

Also, unlike ordinary beads, it does not easily collapse and reduce stress.

Therefore, it is possible to provide a wide range of appropriate elasticity within the combustion chamber seal, and even when tightening with a small tightening force, sufficient tightening force can be generated.
Can provide a reliable seal.

(4) As a result, it is possible to effectively use not only large diesel engines but also small internal combustion engines, and the metal plate laminated gasket can be used reliably.

[Brief explanation of the drawing]

Figure 1 is a plan view of the main parts of a head gasket for an internal combustion engine, Figure 2 is an enlarged sectional view of the end of a conventional wiring type gasket, and Figure 3 is an enlarged sectional view of the end of a conventional bead type gasket. , FIG. 4 is a usage state explanatory diagram corresponding to FIG. 2, and FIG. 5 is a usage state explanatory diagram shown corresponding to FIG. 3. 6th
The figure is an enlarged sectional view of the end of the head gasket showing the first embodiment of the present invention, and FIG. 7 is an explanatory view of the same in use. G...Head gasket, 1...Top plate, 2...
Lower plate, 3a, 3b, 3c...Intermediate plate, 4...Wiring, 5...Combustion chamber seal part, 6...Combustion chamber hole, 7...Bead, 8...Bend part, 9...Seal part , 10... cylinder block, 11... cylinder liner, 11a... flange, 12... cylinder head, 14... bolt hole, 15... water hole, 16...
...Oil hole, 17...Push rod hole, 20...
...Teardrop-shaped space.

Claims (1)

[Claims for Utility Model Registration] A laminated structure consisting of a top plate made of two thin metal plates (top and bottom) and an intermediate plate made of a plurality of thin plates sandwiched between these top plates, in which one of the top plates burns. A folded part surrounding the chamber hole is provided to form a combustion chamber sealing part, and a tip of the intermediate plate or the other surface plate is extended inside the folded part, and the tip is folded back without forming a bead. A head gasket for an internal combustion engine, which has a teardrop-shaped space formed therein, and is configured such that the elastic force of the folded portion presses the back surface of a surface plate located in the vicinity of a combustion chamber sealing portion.