JPH0318781Y2 - - Google Patents

Description

[Detailed description of the invention] a. Purpose of the invention (industrial application field) The gasket according to this invention is used to maintain airtightness and liquidtightness between two surfaces that are joined to each other, for example, when connecting pipes to each other. It can be used by being attached to the inner periphery of the bore hole of a cylinder head gasket that is installed between flanges for connection or between the cylinder head and cylinder block of an engine.

(Prior Art) A gasket as disclosed in Japanese Utility Model Application No. 52-133857 is known as a general-purpose gasket for mounting on various airtight and liquidtight parts.

The gasket disclosed in Japanese Utility Model Publication No. 52-033857, as shown in FIG. , a hollow pipe-shaped and endless annular casing 2 is formed, and the inside of this casing 2 is filled with a powdery filler 3 having heat resistance such as carbon powder.

A gasket constructed in this manner is used by being tightly sandwiched between two surfaces that must maintain airtightness and liquidtightness, such as between the opposing surfaces of flanges for connecting pipes.

(Problems to be Solved by the Invention) However, the conventional gasket constructed and used as described above has the following disadvantages.

That is, the cross section of the casing 3 formed by winding the thin metal plate 1 for filling the filler 3 is circular, and the mating portion 4 in which both the inner and outer peripheral edges of the thin metal plate 1 are closely overlapped is the casing. It is located exactly midway between the inner and outer edges of the gasket, and is in contact with the flat surface that holds the gasket when it is in use, so the gasket can be held between the two surfaces that should maintain airtightness or liquidtightness. In this case, the pressure caused by the contact between the gasket and the plane is particularly large at the mating portion 4, and becomes extremely small at the portions away from the mating portion 4.

In this way, if the contact pressure between the gasket and the surface that is to be kept airtight is particularly large only in the narrow part, the pressure of the fluid existing inside the gasket will be directly applied to this narrow part, causing the above-mentioned contact pressure to increase. Not only will it not be possible to obtain satisfactory sealing performance unless the contact pressure is increased considerably, but if the airtightness of this narrow area is compromised for some reason,
Gas leakage or liquid leakage occurs immediately, so it is not possible to obtain a sufficiently satisfactory airtight performance by pressing the two surfaces that should be kept airtight together with a large force.

The gasket of the present invention eliminates the above-mentioned disadvantages.

b. Structure of the invention (means for solving the problem) The gasket of the invention, like the conventional gasket described above, is made by winding a ring-shaped thin metal plate and closely overlapping both the inner and outer peripheral edges of the thin metal plate. It is constructed by forming a hollow pipe-shaped and endless annular casing, and filling the inside of this casing with a heat-resistant powder filler.

Furthermore, in the gasket of the present invention, the cross-sectional shape of the casing has an inner semicircular arc portion with a concave outer circumferential side and an outer semicircular arc portion with a concave inner circumferential side over the entire circumference. The shape is an ellipse formed by a pair of straight line parts that are parallel to each other, and the overlapping parts of the inner and outer peripheral edges of the thin metal plate are offset toward the outer periphery of one of the straight parts over the entire circumference. ing.

To explain in more detail with reference to the drawings, the gasket of the present invention has the following features as shown in FIG.
A ring-shaped metal thin plate 1 is wound so that the cross section is oval, and the inner and outer peripheral edges of the metal thin plate 1 are closely overlapped to form a hollow pipe-shaped and endless ring-shaped casing 2.

Inside this casing 2, as mentioned above,
Carbon powder, asbestos, kaolin (clay)
It is filled with a powdery filler 3 having heat resistance such as.

The cross-sectional shape of the casing 2 is oval as described above, but the inner semicircular arc part 5 with a concave outer circumferential side and the outer semicircular arc part 6 with a concave inner circumferential side are mutually connected to each other. It is made continuous by a pair of parallel straight parts 7 and 8. For this reason, the thickness of the gasket of the present invention is determined by excluding the semicircular arc parts 5 and 6 located on both the inner and outer peripheral edges, and the thickness of the straight parts 7 and 8. Equal over the entire width.

In addition, in order to form the casing 2, the metal thin plate 1
The mating part 4 in which both the inner and outer peripheral edges of the above-mentioned 1
Of the pair of straight parts 7 and 8, one of the straight parts 7 is provided on one side near the outer periphery.

(Function) The gasket of the present invention configured as described above has the following features:
Similar to the conventional gasket described above, it is used by being sandwiched between two surfaces that must maintain airtightness and liquidtightness, but if the two surfaces are pressed together with strong force, the filler filled in the casing 2 is crushed elastically to some extent.

In this case, the joining part 4 where the inner and outer peripheral edges of the thin metal plates 1 constituting the casing 2 are overlapped is filled with filler material corresponding to the overlap of the thin metal plates 1 that are not elastically compressed. 3 is thinner and therefore less elastically compressible, the force that resists the compressive force acting between the two surfaces is stronger than other parts. Therefore, the pressure at which the outer circumferential surface of the gasket and the plane on which airtightness and liquidtightness are to be maintained by this gasket are brought into contact with each other is slightly greater at the overlapping portion 4 than at other portions.

In this way, if a certain amount of contact pressure is maintained over the somewhat wide straight portions 7 and 8, and the contact pressure is particularly increased at the portions near the outer periphery of these straight portions 7 and 8, the mating portion 4 The pressure of the fluid inside the gasket is no longer directly applied to the gasket, and due to the labyrinth effect, airtightness and liquidtightness between the two opposing surfaces can be maintained well even without a very large contact pressure. I can do it.

(Application example) The gasket of the present invention, which is configured and operates as described above, can be used by being directly sandwiched between flanges, or by being sandwiched between the lower surface of the cylinder head and the upper surface of the cylinder block of an engine. It can also be used by being assembled to the inner peripheral edge of the bore hole of a cylinder head gasket that maintains airtightness and liquidtightness between both sides.

As shown in Figure 3, the cylinder head gasket includes circular bore holes 9, 9 that match the opening shape of the top of the cylinder, as well as through holes 1 for water and oil to flow through.
0, 10, and a small circular hole 11 for inserting the bolt that fixes the cylinder head to the cylinder block.
11 is formed. Among the above-mentioned holes, the inner peripheral edges of the bore holes 9, 9, which require a particularly high degree of airtightness, have traditionally been fitted with thin metal plates called grommets.
It is installed by folding it back into a letter shape, but if the gasket of the present invention constructed as described above is fitted onto the inner circumference of the bore hole 9 as shown in Fig. 2, there is no need to install a grommet. However, the circumferential edge of the bore hole 9 can be kept sufficiently airtight, and the production of the cylinder head gasket can be simplified by omitting the trouble of installing a grommet.

In particular, in the case of a metal cylinder head gasket made of a plurality of laminated metal thin plates, the conventional structure is as shown in FIG.
It has been considered to fold the inner peripheral edge of the thin metal plate exposed on the surface into a U-shaped cross section and fill the inside of this folded portion with a heat-resistant non-metallic cushion material. As shown in Fig. 2, if the cylinder head gasket is fitted later into the inner circumferential edge of the bore hole 9, it will be easier to manufacture the cylinder head gasket than the structure shown in Fig. 5. Good sealing performance can be obtained. In the structure shown in FIG. 2, heat-resistant rubber layers 15 and 15 are provided on both the front and back surfaces of the three thin metal plates 12 to 14 that constitute the metal cylinder head gasket, and the through holes 10 ( (Fig. 3) to prevent water and oil flowing inside from leaking between the thin metal plates.

c. Effects of the invention Since the gasket of the invention is constructed and operates as described above, it is possible to maintain airtightness and liquidtightness between the two opposing surfaces without increasing the force of pressing these two surfaces together. It can be held.

[Brief explanation of the drawing]

Fig. 1 is a half sectional view showing the gasket of the present invention, Fig. 2 is a sectional view showing an example in which this gasket is attached to the inner circumference of the bore hole of a cylinder head gasket, and Fig. 3 is a cylinder head gasket. 1
FIG. 4 is a plan view showing an example, FIG. 4 is a sectional view showing a conventional gasket, and FIG. 5 is a partial sectional view showing the inner peripheral edge of a bore hole of a conventional cylinder head gasket. 1: thin metal plate, 2: casing, 3: filler,
4: Matching part, 5, 6: Semicircular arc part, 7, 8: Straight part, 9: Bore hole, 10: Through hole, 11: Small circular hole, 1
2, 13, 14: thin metal plate, 15: rubber layer.

Claims (1)

[Scope of utility model registration request] A heat-resistant powder filler is placed inside a hollow pipe-shaped and endless annular casing, which is formed by winding a ring-shaped metal thin plate and closely overlapping both the inner and outer peripheral edges of the metal thin plate. In the gasket formed by filling the cross-sectional shape of the casing, the inner semicircular arc part with a concave outer circumferential side and the outer semicircular arc part with a concave inner circumferential side are mutually connected to each other. It is characterized by an oval shape made up of a continuous pair of parallel straight parts, and an overlapping part of both the inner and outer peripheral edges of the thin metal plate is provided along the entire circumference, near the outer periphery of one of the straight parts. gasket.