JP2618290B2 - Metal gasket - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal gasket used between a deck surface of a cylinder head and a cylinder block of an internal combustion engine, and more particularly to a combustion chamber hole which is surrounded by a convex bead having a semicircular cross section. The present invention relates to an improvement in a metal gasket that surrounds holes, bolt holes, and the like with step beads to seal between deck surfaces.

[0002]

2. Description of the Related Art Conventionally, a metal gasket is inserted into a joint surface between a cylinder head and a cylinder block of an internal combustion engine, and a bead formed on a periphery of a combustion chamber hole of the metal gasket is elastically deformed by a bolt tightening force when the cylinder head is fastened. By forming an elastic sealing line on the deck surface by the elastic restoring force at the time of this deformation, the bead is sealed by following the distortion of the deck surface.

As shown in FIG. 4 (a), such a metal gasket includes a convex bead 1 having a semicircular cross section surrounding a combustion chamber hole 7 of a metal gasket G1, a cooling water hole 8, an oil hole 10, and a bolt. A cooling water hole step bead 2, an oil hole step bead 3, and a bolt hole step bead 5 are provided around the hole 11 and the like, respectively. Is sealed.

[0004]

The cross section of the metal gasket is shown in FIG. 4 (b) (AA in FIG. 4 (a)).
As shown in FIG. 4, a cooling water hole step bead 2 and an oil hole step bead 3 have a step bead adjacent portion Z1 which is very close to each other. However, since these beads continuously form step beads (FIG. 4). (See (b) and (c)), the load increases as the step beads 2 and 3 approach each other, and the load concentrates on the step bead adjacent portion Z1 and the deck surface pressure becomes uneven. .

The present invention has been made in order to solve such a problem, and even in a portion where step beads are close to each other, it is possible to obtain a load similar to that of another bead and average the surface pressure distribution. It is an object to provide a metal gasket that can be used.

[0006]

A metal gasket of the present invention for solving the above-mentioned problems will be described with reference to FIG. 1 corresponding to an embodiment. A combustion chamber hole 7 formed in an elastic metal plate has a semicircular convex section. In the metal gasket surrounded by the bead 1, the periphery of the cooling water hole 8, the oil hole 10, the bolt hole 11 and the like other than the combustion chamber hole are surrounded by the step beads 2, 3, and 5, respectively. It is characterized in that the bead shapes of the portions where 2, 3, and 5 are close to each other are integrated into a convex bead 4 having a semicircular cross section.

[0007]

FIG. 1A is a cross-sectional view of a metal gasket formed according to the structure of the present invention, taken along line AA of FIG. 1A. As shown in FIG. Is formed integrally with the convex bead 4 having a semicircular cross section. This convex bead 4 is formed as shown in FIG.
As shown in FIG. 3 (a), the step bead 2 and the step bead 3 provided around the cooling water hole 8 and the oil hole 10 respectively gradually form one semicircular cross-section from a part close to each other. This is a convex bead 4 having a shape.

When the characteristics of the convex bead 4 having a semicircular cross section are compared with those of other beads, the result is as shown in FIG.
A bead (f) is a bead of the present invention in which a step bead is formed continuously with a step bead adjacent to each other in a stepped shape, and a step bead (f) is formed as a convex bead 4 having a semicircular cross section. , Bead (g) is a general step bead in which step beads do not approach each other and stand alone. As shown in the characteristic diagram, even when the bead (e) and the bead (f) have the same bead width L, the bead (e) and the bead (f) have a bending characteristic of (e) <(f) <(g) with respect to a constant load. By forming the step bead adjacent portion Z0 as a convex bead (f) having a semicircular cross section, the characteristics can be approximated to those of a general step bead (g), and the surface pressure can be averaged. .

As a comparative example of the present invention, Japanese Utility Model Application No.
There is a metal gasket described in 106419. This metal gasket is, for example, a bead that surrounds a lubricating oil port formed near the cylinder port and is extended in the direction of the cylinder port to provide a widened portion, and a bolt hole is formed in the widened portion. As another embodiment, a bead surrounding an opening for a lean mixture is continuously connected to a bead surrounding an opening for a rich mixture close thereto, and a widened portion is formed between the openings. However, such a widened portion forms a portion adjacent to the step bead and the step beat to cause a concentrated load, which is disadvantageous in averaging the surface pressure.

[0010]

FIG. 1 is a view showing one embodiment of a metal gasket according to the present invention. FIG. 1 (a) is a partially cutaway perspective view of a metal gasket, and FIG. A of 1 (a)
FIG. 1C is a sectional view taken along the line A, and FIG. 1C is a view taken in the direction of arrow B in FIG. FIG. 2 is a characteristic diagram showing the relationship between load and deflection when a convex bead having a circular cross section according to the present invention is compared with other beads. FIG. 3 is a cross-sectional view of a molding die for producing a metal gasket according to the present invention. FIG. 3 (a) is a molding die of a step bead, and FIG. 3 (b) is a molding of a convex bead having a semicircular cross section. It is a fragmentary sectional view showing a metallic mold. In these figures, the same parts as those in FIG. 4 are denoted by the same reference numerals.

In the metal gasket G0 of this embodiment, a combustion chamber hole 7 perforated in an elastic metal plate is surrounded by a convex bead 1 having a semicircular cross section, and the periphery of the cooling water hole 8 is surrounded by the step bead 2 and the periphery of the oil hole 10. Is surrounded by a step bead 3 and a step bead 5 around the bolt hole 11, and the step bead 2 of the cooling water hole 8 and the step bead 3 of the oil hole 10 are close to each other from a range a (see FIG. 1 (c)). It is formed so as to gradually change into one convex bead 4 having a semicircular cross section. The metal gasket of the present invention can be formed using a mold shown in FIG. 3 (a) and 3 (b), reference numeral 21 denotes an upper die convex portion, 22 denotes a lower die concave portion, 23 denotes an upper die wrinkle pressing concave portion, 24 denotes a lower die wrinkle pressing convex portion, 25 denotes an upper die convex portion,
26 is a lower mold recess, 27 is a stopper for the upper mold wrinkle holding recess 23, and 28 is a wrinkle holding spring for the upper wrinkle holding recess 23. The step bead 2 of the cooling water hole 8 and the step bead of the oil hole 10 are provided. 3 gradually decreases the width of the upper mold projection 21 from b1 to b2 in the range a, and reduces the amount of depression of the lower mold recess 22 from C1 to C3.
As a result, the step S is gradually pressed from the step bead shown in FIG. 1 (c) to a convex bead having a semicircular cross section. Can change.

In this embodiment, the case where the step bead 2 of the cooling water hole 8 and the step bead 3 of the oil hole 10 are close to each other is a convex beat having a semicircular cross section is described. The invention can be applied to a part where any step beads are close to each other.

[0013]

As described above, according to the metal gasket of the present invention, the portions where the step beads are close to each other are integrated into a convex bead having a semicircular cross section. Can be approximated to a general step bead load, the surface pressure distribution over the entire gasket surface can be averaged, and a metal gasket excellent in sealing performance can be obtained.

Such a metal gasket according to the present invention can be applied not only to a single plate but also to a laminated type and a type in which a stopper is also used around a combustion chamber.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a metal gasket according to the present invention, FIG. 1 (a) is a partial perspective view in which a part of the metal gasket is cut away, and FIG. A of 1 (a)
FIG. 1C is a sectional view taken along the line A, and FIG. 1C is a view taken in the direction of the arrow B in FIG.

FIG. 2 is a characteristic diagram showing a relationship between load and deflection when a convex bead having a circular cross section according to the present invention is compared with other beads.

FIG. 3 is a cross-sectional view of a molding die for producing a metal gasket according to the present invention. FIG. 3 (a) is a step-bead molding die, and FIG. FIG. 4 is a partial cross-sectional view illustrating a bead forming die.

FIG. 4 is a view showing one embodiment of a conventional metal gasket, FIG. 4 (a) is a partial perspective view in which a part of the metal gasket is cut away, and FIG. 4 (b) is FIG. FIG. 4A is a cross-sectional view taken along line AA, and FIG. 4C is a view taken in the direction of arrow B in FIG.

[Description of sign]

DESCRIPTION OF SYMBOLS 1 ... Semi-circular convex bead, 2 ... Cooling water hole step bead, 3 ... Oil hole step bead, 4 ... Semi-circular convex bead near the step bead, 5 ... Bolt hole step bead, 8 ... Cooling water hole 10, 10 oil holes, 1
1. Bolt holes.

Claims (1)

(57) [Claims] 1. A metal gasket comprising a combustion chamber hole (7) perforated in an elastic metal plate surrounded by a convex bead (1) having a semicircular cross section, wherein a cooling water hole (8) other than the combustion chamber hole and an oil hole are provided. (1
0), Step beads (2,
(3, 5) and each step bead (2, 3, 5)
A metal gasket characterized by integrating a bead shape at a portion close to each other into a convex bead (4) having a semicircular cross section.