Cylinder head cover gasket

Abstract

To prevent a gasket mounted on a holding groove of a cylinder head cover from coming off of the cylinder head cover.SOLUTION: A cylinder head cover gasket has: a base part 4a that is inserted into a holding groove 3; a seal part 4h that is provided on a cylinder head side of the base part 4a, and is in contact with a flange surface of the cylinder head; and holding parts 4f, 4g that are provided on both sides of the base part 4a, have an obtuse triangular cross-sectional shape, and are in contact with an inner wall surface 3a of the holding groove 3 at tip portions 4g-3, 4f-3 in a state where the tip portions 4g-3, 4f-3 with one acute angle included in the obtuse triangular shape face the opening side of the holding groove 3.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a structure of a cylinder head cover gasket that is sandwiched between a cylinder head and a cylinder head cover. [Background technology]

[0002] The gap between the cylinder head of the engine and the cylinder head cover that covers the top surface of the cylinder head is sealed by a gasket made of an elastic body such as rubber molded into a frame shape.

[0003] The gasket is attached to a mounting groove formed along the periphery of the flange surface of the cylinder head cover that faces the cylinder head, and is sandwiched between the cylinder head and the cylinder head cover so that the gasket is in close contact with the flange surface of the cylinder head that faces the cylinder head cover (see Patent Document 1).

[0004] The embodiment shown in FIG. 5 of Patent Document 1 describes a structure having a base that fits into the gasket retaining groove, and having substantially triangular protrusions on both sides of the base, one on the outer side and one on the inner side of the cylinder head cover, that locally press against the side of the gasket retaining groove. This holds the gasket in the gasket retaining groove of the cylinder head cover and prevents the gasket from falling off when, for example, the cylinder head is removed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2-256967 Summary of the Invention [Problem to be solved by the invention]

[0006] Generally, cylinder head covers are die-cast, and therefore the gasket retaining groove of the cylinder head cover has a cross section with a substantially trapezoidal draft. In the structure of the embodiment shown in Fig. 5 of Patent Document 1, the gasket is retained by a substantially triangular protrusion that is locally pressed against the side surface of the gasket retaining groove, but the weight of the gasket cannot be supported by the retaining force generated by friction between the side surface of the gasket retaining groove and the protrusion, and there remains a problem in preventing the gasket from falling off.

[0007] Furthermore, when assembling a cylinder head cover to the cylinder head of an engine, the gasket is pressed into the gasket retaining groove so that the protrusion on the base of the gasket is pressed against the side of the gasket retaining groove, thereby fitting the gasket in the gasket retaining groove. However, because the side of the gasket retaining groove is inclined due to the draft angle, the reaction force acting on the gasket from the side of the gasket retaining groove acts in a direction that pushes the gasket out of the gasket retaining groove, which may cause the gasket to fall off the cylinder head cover.

[0008] The present invention has been devised in view of the above-mentioned problems, and one of its objects is to prevent a gasket attached to a retaining groove of a cylinder head cover from falling off from the cylinder head cover. [Means for solving the problem]

[0009] The present invention has been made to solve at least part of the above problems, and can be realized in the following aspects or application examples.

[0010] The cylinder head cover gasket according to this application example is a cylinder head cover gasket that is provided on the peripheral edge of a cylinder head cover, is fitted into a retaining groove that has a trapezoidal cross section and has two opposing inclined inner wall surfaces, and seals between the cylinder head and the cylinder head cover, and is characterized by comprising: a base that is inserted into the retaining groove, a sealing portion that is provided on the cylinder head side of the base and abuts on a flange surface of the cylinder head, and retaining portions that are provided on two side surfaces of the base that face the two inner wall surfaces of the retaining groove, respectively, and have an obtuse triangular cross section, with a tip portion of one acute angle included in the obtuse triangular shape abutting against the inner wall surfaces of the retaining groove at the tip portion with the tip portion facing the opening side of the retaining groove.

[0011] According to this application example, the retaining portion has a cross-sectional shape of an obtuse triangle, and a tip portion of one acute angle included in the obtuse triangle is brought into contact with the inner wall surface of the retaining groove with the tip portion facing the opening side of the retaining groove, thereby generating a larger frictional force between the inner wall surface of the retaining groove and the retaining portion. This frictional force acts in a direction that keeps the cylinder head cover gasket in the retaining groove, so that the gasket attached to the retaining groove of the cylinder head cover does not fall off from the cylinder head cover, improving the ease of assembly. Effect of the Invention

[0012] According to the present invention, it is possible to provide a cylinder head cover gasket that can prevent the gasket, which is attached to the retaining groove of the cylinder head cover, from falling off from the cylinder head cover. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a diagram illustrating a schematic view of a lower side surface of a cylinder head cover to which a cylinder head cover gasket according to one embodiment is attached. [Diagram 2]2 is a vertical cross-sectional view taken in the direction of the arrow A in FIG. 1, showing the cylinder head cover shown in FIG. 1 and a cylinder head cover gasket attached thereto. [Diagram 3] FIG. 2 is a diagram showing a lower side of a cylinder head cover gasket according to one embodiment. [Figure 4] 4 is a vertical cross-sectional view (view taken in the direction of the arrow B in FIG. 3) of the cylinder head cover gasket according to the embodiment. [Diagram 5] 2 is a vertical cross-sectional view (view taken in the direction of the arrow A in FIG. 1) showing a state in which a cylinder head cover gasket according to one embodiment is inserted into a retaining groove. FIG. [Figure 6] 5A and 5B are diagrams for explaining the relationship between the first and second return projections and the side surfaces of the retaining groove of the cylinder head cover gasket according to the embodiment. [Figure 7] 6A and 6B are diagrams for explaining forces acting between first and second return projections and retaining groove side surfaces of the cylinder head cover gasket according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The embodiments of the present invention will be described with reference to the drawings. The following embodiments are merely examples, and are not intended to exclude the application of various modifications and techniques not specified in the embodiments. The configurations of the following embodiments can be modified in various ways without departing from the spirit of the embodiments. In addition, they can be selected or combined as necessary.

[0015] [1. Configuration] In this embodiment, the arrangement of the engine is described as being vertical, and a cylinder head cover gasket 4 that seals the gap with the cylinder head is attached to a cylinder head cover 1 that covers the top surface of the engine cylinder head. The cylinder head cover gasket 4 is also called a rubber seal or rubber member.

[0016] In this embodiment, the cylinder head side (not shown) of the cylinder head cover 1 is referred to as the lower side, and the opposite side is referred to as the upper side. In the drawings, "UP" indicates the upper side of the cylinder head cover 1, and "DN" indicates the lower side of the cylinder head cover 1.

[0017] FIG. 1 is a schematic diagram showing the underside of a cylinder head cover 1 to which a cylinder head cover gasket 4 according to one embodiment is attached, and FIG. 2 is a vertical cross-sectional view taken in the direction of the arrow A in FIG. 1, showing the cylinder head cover 1 shown in FIG. 1 and the cylinder head cover gasket 4 attached thereto.

[0018] 1 shows a cylinder head cover 1 having a flange surface 2 formed in a strip shape along the periphery of the lower side of the cylinder head cover 1. The flange surface 2 of the cylinder head cover 1 is attached to a flange surface formed along the periphery of the upper side of a cylinder head (not shown).

[0019] Further, a retaining groove 3 into which a cylinder head cover gasket 4 is inserted is formed along the periphery of the cylinder head cover 1 on the flange surface 2. The inner wall surface of the retaining groove 3 may be referred to as a retaining groove side surface 3a.

[0020] Since the cylinder head cover 1 is die-cast, the retaining groove 3 has a trapezoidal cross section with a draft gradient, as shown in Fig. 2, Fig. 5, etc. In other words, the retaining groove side surface 3a of the retaining groove 3 is inclined so that the groove width increases from the top to the bottom. The retaining groove 3 is provided on the peripheral edge of the cylinder head cover 1, and is an example of a retaining groove having a trapezoidal cross section with two opposing inclined inner wall surfaces (retaining groove side surface 3a). As will be described later with reference to Fig. 6, the retaining groove side surface 3a of the retaining groove 3 is inclined so as to form a taper angle a with respect to a vertical plane. The retaining groove 3 also has an opening at the lower end, and the cylinder head cover gasket 4 is inserted from this opening.

[0021] FIG. 3 is a view showing the underside of a cylinder head cover gasket 4 according to one embodiment, and FIG. 4 is a vertical cross-sectional view thereof (view taken in the direction of the arrow B in FIG. 3).

[0022] The cylinder head cover gasket 4 is formed into a ring shape from an elastic body such as rubber, and is continuously molded into a frame shape similar to the retaining groove 3, as shown in Fig. 3. Hereinafter, in the frame-shaped cylinder head cover gasket 4, the inside of the frame will be referred to as the "inside" and the outside of the frame will be referred to as the "outside." In the drawings, "IN" indicates the inside of the cylinder head cover gasket 4, and "OUT" indicates the outside of the cylinder head cover gasket 4.

[0023] In addition, the upper end of the cylinder head cover gasket 4 may be referred to as the top, and the lower end as the bottom. The bottom of the cylinder head cover gasket 4 may be referred to as the sealing surface 4h. The up-down direction of the cylinder head cover gasket 4 is based on the state in which the cylinder head cover gasket 4 is attached to the retaining groove 3.

[0024] As shown in FIG. 4, the cylinder head cover gasket 4 has a base 4a that is inserted into the retaining groove 3 when attaching it to the cylinder head cover 1, and sealing members 4b, 4c that are sandwiched between the flange surface 2 of the cylinder head cover 1 and the flange surface of the cylinder head to seal the gap between the cylinder head cover 1 and the cylinder head.

[0025] Hereinafter, the state in which the cylinder head cover gasket 4 is attached to the cylinder head cover 1 may be referred to as a "gasket attached state." Also, the state in which the cylinder head cover 1 in the gasket attached state is attached to the cylinder head may be referred to as a "cylinder head cover attached state."

[0026] The sealing member 4b is formed on the bottom side of the cylinder head cover gasket 4 so as to protrude from the outer side surface 4a-1 of the base 4a toward the outside of the cylinder head cover gasket 4. The sealing member 4c is formed on the bottom side of the cylinder head cover gasket 4 so as to protrude from the inner side surface 4a-1 of the base 4a toward the inside of the cylinder head cover gasket 4. The base 4a is formed so that a wall-shaped member sandwiched between the inner side surface 4a-1 and the outer side surface 4a-1 is continuous in a frame shape. The inner side surface 4a-1 and the outer side surface 4a-1 may be formed parallel or approximately parallel.

[0027] 4, the upper surface and the inner surface of the seal member 4c are formed at a right angle, and the section between the upper surface and the outer surface of the seal member 4b is formed in an arc shape.

[0028] The seal surface 4h is formed with protrusions 4e, 4d that protrude downward. The protrusion 4e is formed below the seal members 4b, 4c, and the protrusion 4d is formed below the base portion 4a.

[0029] When the cylinder head cover is attached, the upper surfaces of the seal members 4b, 4c are pressed against the flange surface 2 of the cylinder head cover 1. The seal surface 4h is pressed against the flange surface of the cylinder head. That is, the lower surfaces (projection 4e) and the projections 4d, 4d of the seal members 4b, 4c are pressed against the flange surface of the cylinder head. The seal surface 4h is an example of a seal portion that is provided on the cylinder head side of the base 4a and comes into contact with the flange surface of the cylinder head.

[0030] In addition, a first return protrusion 4f and a second return protrusion 4g are formed on each of the inner and outer side surfaces 4a-1 of the base 4a. Note that, on each side surface 4a-1 of the base 4a, the first return protrusion 4f is disposed higher than the second return protrusion 4g.

[0031] In the first return projection 4f, the outer surface 4f-1, the inner surface 4f-2, and the side surface 4a-1 of the base 4a form a triangle, and in particular, the inner surface 4f-2 and the side surface 4a-1 of the base 4a form an obtuse angle, and the outer surface 4f-1 and the inner surface 4f-2 form an acute angle. In the gasket-attached state, the first return projection 4f abuts against the inner wall surface (retaining groove side surface 3a) of the retaining groove 3 at its tip portion (apex 4f-3: see FIG. 5) of the acute angle formed by the outer surface 4f-1 and the inner surface 4f-2 with the tip portion facing the opening side (lower side) of the retaining groove 3.

[0032] The first return protrusion 4f is provided on each of two side surfaces 4a-1, 4a-1 that face the two inner wall surfaces (retaining groove side surfaces 3a) of the retaining groove 3 in the base 4a, has an obtuse triangular cross-sectional shape, and is an example of a retaining portion that abuts against the inner wall surfaces (retaining groove side surfaces 3a) of the retaining groove 3 at its tip portion (apex 4f-3) of one acute angle included in the obtuse triangular shape with the tip portion facing toward the opening side of the retaining groove 3.

[0033] Here, in the cylinder head cover gasket 4, when its base 4a side is inserted into the retaining groove 3 of the cylinder head cover 1, with the upper surfaces of the sealing members 4b, 4c abutting against the flange surface 2, the distance between the respective apexes 4f-3 of a pair of opposing first return protrusions 4f across the base 4a is configured to be larger than the groove width at that position.

[0034] As a result, when the base 4a side of the cylinder head cover gasket 4 is inserted into the retaining groove 3 of the cylinder head cover 1, with the upper surfaces of the sealing members 4b, 4c abutting against the flange surface 2, the top 4f-3 of the first return protrusion 4f is pressed against the retaining groove side surface 3a of the retaining groove 3 by the elasticity of the first return protrusion 4f.

[0035] Similarly, in the second return projection 4g, the outer surface 4g-1, the inner surface 4g-2, and the side surface 4a-1 of the base 4a form a triangle, and in particular, the inner surface 4g-2 and the side surface 4a-1 of the base 4a form an obtuse angle, and the outer surface 4g-1 and the inner surface 4g-2 form an acute angle. In the gasket-attached state, the second return projection 4g abuts against the inner wall surface (retaining groove side surface 3a) of the retaining groove 3 at the tip portion (apex 4g-3: see FIG. 5) of the acute angle formed by the outer surface 4g-1 and the inner surface 4g-2 with the tip portion facing the opening side (lower side) of the retaining groove 3.

[0036] The second return protrusion 4g is provided on each of the two side surfaces 4a-1, 4a-1 that face the two inner wall surfaces (retaining groove side surfaces 3a) of the retaining groove 3 in the base 4a, has an obtuse triangular cross-sectional shape, and is an example of a retaining portion that abuts against the inner wall surfaces (retaining groove side surfaces 3a) of the retaining groove 3 at its tip portion (apex 4g-3) with the tip portion facing the opening side of the retaining groove 3.

[0037] Furthermore, in the cylinder head cover gasket 4, when its base 4a side is inserted into the retaining groove 3 of the cylinder head cover 1, with the upper surfaces of the sealing members 4b, 4c abutting against the flange surface 2, the distance between the respective apexes 4g-3 of a pair of opposing second return protrusions 4g facing each other across the base 4a is also configured to be larger than the groove width at that position.

[0038] As a result, when the base 4a side of the cylinder head cover gasket 4 is inserted into the retaining groove 3 of the cylinder head cover 1, with the upper surfaces of the sealing members 4b, 4c abutting against the flange surface 2, the top 4g-3 of the second return protrusion 4g is pressed against the retaining groove side surface 3a of the retaining groove 3 by the elasticity of the second return protrusion 4g.

[0039] In addition, the distance between the apexes 4g-3 of a pair of second return projections 4g facing each other across the base 4a is configured to be longer than the distance between the apexes 4f-3 of a pair of first return projections 4f facing each other across the base 4a.

[0040] FIG. 5 is a vertical cross-sectional view (viewed in the direction of the arrow A in FIG. 1) showing a state in which a cylinder head cover gasket 4 according to one embodiment is inserted into a retaining groove 3. As shown in FIG.

[0041] 5, in a state where the cylinder head cover gasket 4 is inserted into the retaining groove 3, an outer surface 4f-1 of each first return projection 4f and an outer surface 4g-1 of each second return projection 4g abut against the retaining groove side surface 3a of the retaining groove 3. More specifically, an apex 4f-3 formed by the outer surface 4f-1 and inner surface 4f-2 of each first return projection 4f and an apex 4g-3 formed by the outer surface 4g-1 and inner surface 4g-2 of each second return projection 4g abut against the retaining groove side surface 3a.

[0042] FIG. 6 is a view for explaining the relationship between the first return projection 4f and the second return projection 4g of the cylinder head cover gasket 4 according to one embodiment and the retaining groove side surface 3a.

[0043] For convenience, FIG. 6 shows a state in which the retaining groove side surface 3a and the cylinder head cover gasket 4 (the first returning projection 4f and the second returning projection 4g) are spaced apart from each other.

[0044] The outer surface 4f-1 of the first return projection 4f is inclined to form an angle b with respect to the vertical plane. The outer surface 4g-1 of the second return projection 4g is inclined to form an angle c with respect to the vertical plane. The cylinder head cover gasket 4 is configured such that the angle b of the outer surface 4f-1, the angle c of the outer surface 4g-1, and the taper angle a of the retaining groove side surface 3a satisfy the relationship c>b>a.

[0045] Also, the inner surface 4f-2 of the first protrusion 4f is configured to have a depression angle d, and the inner surface 4g-2 of the second protrusion 4g is configured to have a depression angle e. d>e may be satisfied.

[0046] [2. Actions and Effects] The base 4a of the cylinder head cover gasket 4 constructed as described above is inserted into the retaining groove 3 of the cylinder head cover 1, and the cylinder head cover gasket 4 is attached to the cylinder head located below it, with the cylinder head cover gasket 4 facing downward as shown in Figure 7.

[0047] At that time, in the cylinder head cover gasket 4, when its base 4a is inserted into the retaining groove 3 of the cylinder head cover 1, with the upper surfaces of the seal members 4b, 4c abutting against the flange surface 2, each apex 4f-3 of the first return projections 4f and each apex 4g-3 of the second return projections 4g are pressed against the retaining groove side surface 3a of the retaining groove 3. As a result, the frictional force generated between the retaining groove side surface 3a and the first return projections 4f and second return projections 4g acts in a direction to retain the cylinder head cover gasket 4 in the retaining groove 3, realizing the effect of preventing the cylinder head cover gasket 4 from coming off.

[0048] FIG. 7 is a view for explaining forces acting between the first and second return projections 4f, 4g and the retaining groove side surface 3a in the cylinder head cover gasket 4 according to one embodiment.

[0049] 7, the thick arrows along the retaining groove side surface 3a indicate the frictional force generated between the retaining groove side surface 3a and the first and second returning projections 4f, 4g. The frictional force is determined based on the force F with which the first and second returning projections 4f, 4g press against the retaining groove side surface 3a and the friction coefficient μ between the retaining groove side surface 3a and the cylinder head cover gasket 4.

[0050] The solid arrows shown inside the cylinder head cover gasket 4 indicate the resultant force F of the frictional forces generated between the retaining groove side surface 3a and the first direction return projection 4f and the second direction return projection 4g. μ The apex 4f-3 of the first return projection 4f and the apex 4g-3 of the second return projection 4g are caught on the retaining groove side surface 3a, which produces an effect similar to the barb effect of a fishhook, and can produce a larger frictional force (friction coefficient μ).

[0051] On the other hand, the dotted arrow shown inside the cylinder head cover gasket 4 indicates a force W that tries to push the cylinder head cover gasket 4 out of the retaining groove 3. This force W includes the weight of the cylinder head cover gasket 4 and a force that acts on the retaining groove side surface 3a having the taper angle a to push the cylinder head cover gasket 4 out of the retaining groove 3.

[0052] In the present cylinder head cover gasket 4, the resultant force F of the frictional forces generated between the retaining groove side surface 3a and the first return projection 4f and the second return projection 4g is μ However, by making the force W equal to or greater than the force W that tries to get the cylinder head cover gasket 4 out of the retaining groove 3, it is possible to prevent the cylinder head cover gasket 4 from falling off the cylinder head cover 1.

[0053] In other words, even if the retaining groove 3 has a trapezoidal cross section due to the draft gradient, the cylinder head cover gasket 4 fitted into the retaining groove 3 can be prevented from falling off from the retaining groove 3 due to the frictional force generated between the first return protrusion 4f and the second return protrusion 4g and the retaining groove side surface 3a.

[0054] In addition, two protrusions, the first protrusion 4f and the second protrusion 4g, are provided on the inside and outside of the base 4a in the vertical direction, and the distance between the apexes 4g-3 of the pair of second protrusions 4g facing each other across the base 4a is longer than the distance between the apexes 4f-3 of the pair of first protrusions 4f facing each other across the base 4a. This allows the first protrusion 4f and the second protrusion 4g to come into contact with the retaining groove side surface 3a in the retaining groove 3, which has a trapezoidal cross-sectional shape and whose groove width becomes wider toward the bottom, to generate a larger frictional force, thereby improving the effect of preventing the cylinder head cover gasket 4 from coming off.

[0055] In addition, when the cylinder head cover is attached, the upper surfaces of the sealing members 4b, 4c are pressed against the flange surface 2 of the cylinder head cover 1, and the lower surfaces (protrusion 4e) and protrusions 4d, 4d of the sealing members 4b, 4c are pressed against the flange surface of the cylinder head, thereby improving the sealing performance.

[0056] The upper and inner surfaces of the seal member 4c are formed at a right angle, so that the contact area between the seal member 4c and the flange surface 2 is increased, thereby improving the sealing performance when the cylinder head cover is attached.

[0057] [3.Other] In the above-described embodiment, the configuration of the cylinder head cover gasket 4 is one example, and the disclosed technology is not limited to the above-described embodiment, and can be implemented in various modifications without departing from the spirit of the present embodiment.

[0058] For example, in the above-mentioned embodiment, a total of four return protrusions of two types, the first return protrusion 4f and the second return protrusion 4g, are formed on the base 4a, but this is not limited to this. Three or more types of return protrusions may be formed on the base 4a, and three or less or five or more return protrusions may be formed on the base 4a. When three or more types of return protrusions are formed in a line in the vertical direction, it is desirable to increase the protruding amount of the return protrusions toward the bottom.

[0059] In the above-described embodiment, the apex of the base 4a is formed to have an arc-shaped cross section, but this is not limited thereto. For example, the apex of the base 4a may be formed to match the shape of the holding groove 3, and may have a rectangular cross section. In addition, although the present embodiment has been described with respect to a vertically mounted engine, the present invention is not limited to this, and may be, for example, a horizontally mounted engine or a horizontally opposed engine. Therefore, the above-mentioned up-down direction is merely an example. [Explanation of symbols]

[0060] 1 Cylinder head cover 2 Flange surface 3 Retaining groove 3a Retaining groove side (inner wall surface) 4 Cylinder head cover gasket 4a base 4a-1 Side 4b, 4c Sealing material 4d,4e Protrusion 4f First return protrusion (retaining part) 4f-1 External surface 4f-2 Inner surface 4f-3 Top 4g Second protrusion (holding part) 4g-1 External surface 4g-2 Inner surface 4g-3 top 4h Sealing surface (sealing part)

Claims

[Claim 1] A cylinder head cover gasket that is provided on a peripheral portion of a cylinder head cover, is fitted into a retaining groove having a trapezoidal cross section and two opposing inclined inner wall surfaces, and seals between a cylinder head and the cylinder head cover, A base portion to be inserted into the holding groove; a seal portion provided on the cylinder head side of the base portion and in contact with a flange surface of the cylinder head; a retaining portion provided on each of two side surfaces of the base portion that face the two inner wall surfaces of the retaining groove, the retaining portion having an obtuse triangular cross section, the tip portion of one acute angle included in the obtuse triangular shape being brought into contact with the inner wall surface of the retaining groove with the tip portion facing the opening side of the retaining groove; A cylinder head cover gasket comprising:

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