Cylinder head gasket

Abstract

To provide a cylinder head gasket capable of suppressing overheat by suppressing intrusion of a combustion gas into a water hole.SOLUTION: Rubber coatings 12 and 13 are applied on both front and rear faces of a first gasket substrate 5 and a second gasket substrate 6 but K-shaped peeling parts 12A and 13A, in which the rubber coatings 12 and 13 are forcibly peeled, are provided at positions between a bolt hole 8 and a water hole 9. Similar K-shaped notches are formed at positions corresponding to the peeling parts 12A and 13A on an intermediate plate 7. In a state where a cylinder head gasket 1 is mounted between a cylinder head and a cylinder block, in a case where a combustion gas G is leaked over a full bead 5B (6B) to the outside thereof, the combustion gas G is exhausted from an outer edge 1B of the cylinder head gasket 1 to the outside via a gap 15 between the pealing parts 12A and 13A and mating materials and the notches.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a cylinder head gasket, and more particularly to a cylinder head gasket capable of suppressing the intrusion of combustion gas into water holes.

Background Art

[0002] Conventionally, a cylinder head gasket configured by laminating a plurality of gasket substrates, in which a plurality of combustion chamber holes, water holes, and bolt holes are formed at required positions, and rubber coatings are applied to both the front and back surfaces of each gasket substrate, is known (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, FIGS. 8(a) and 8(b) schematically show the main part and the cross section of the above-described conventional cylinder head gasket 1. This conventional cylinder head gasket 1 is configured by laminating a plurality of gasket substrates 5 and 6 and an intermediate plate 7 disposed therebetween, and a plurality of combustion chamber holes 1A (5A to 7A) are formed at required positions. Full beads 5B and 6B are formed on the gasket substrates 5 and 6 so as to surround the combustion chamber holes 5A and 6A. Further, a plurality of bolt holes 8 and water holes 9 are formed at required positions, and half beads 5C and 6C are formed on both the gasket substrates 5 and 6 so as to surround the individual water holes 9. Furthermore, rubber coatings 12 and 13 are applied to both the front and back surfaces of both the gasket substrates 5 and 6. In this conventional cylinder gasket 1, the cylinder head gasket 1 is tightly fastened between the cylinder block and the cylinder head by bolts installed in bolt holes 8 at a position outside the water hole 9. Therefore, if combustion gas G leaks outward beyond the full beads 5B and 6B surrounding the combustion chamber holes 1A (5A and 6A), it is difficult for the combustion gas G to escape outward from the cylinder head gasket 1 through the gap between the upper and lower gasket substrates 5 and 6 and between their mating materials. As a result, there was a risk that the combustion gas G leaking outward beyond the full beads 5B and 6B could enter the water hole 9 and cause the engine to overheat. Furthermore, although the diagram is omitted, in conventional cylinder head gaskets, which have a configuration in which a half bead surrounds all of the water holes endlessly from the outside, rather than surrounding individual water holes with a half bead 5C (6C) as shown in Figure 8(a), as mentioned above, if the combustion gas G exceeds the full bead 5B (6B) and leaks outwards, there is a problem that the combustion gas G can easily enter the water holes 9, which can easily cause overheating. [Means for solving the problem]

[0005] In view of the circumstances described above, the present invention relates to a cylinder head gasket comprising at least one gasket substrate coated on at least one of its front or back surfaces, and a plurality of combustion chamber holes, water holes and bolt holes drilled at predetermined positions on the gasket substrate, wherein a bead is formed on the gasket substrate surrounding each of the combustion chamber holes, A peeled portion is formed on the gasket substrate where the coating is removed, at a position between the water holes and bolt holes, and extending from an adjacent outer position of the bead to the outer edge of the cylinder head gasket. The above-mentioned peeling portion consists of an arc-shaped portion located adjacent to the bead and outward, and a discharge portion located between the water hole and the bolt hole, extending from the arc-shaped portion to the outer edge of the cylinder head gasket. It comprises a first gasket substrate located on the upper side, a second gasket substrate located on the lower side, and an intermediate plate provided between the first gasket substrate and the second gasket substrate, and is constructed by laminating the two gasket substrates and the intermediate plate. The intermediate plate is provided with a plurality of combustion chamber holes, water holes, and bolt holes drilled at predetermined positions in the intermediate plate so as to correspond to the combustion chamber holes, water holes, and bolt holes of the first gasket substrate and the second gasket substrate described above. The first gasket substrate and the second gasket substrate are coated on both their front and back surfaces, and the peeling portions are formed on both their front and back surfaces. The peeling portion is formed in a roughly K shape by the arc portion and the bifurcated discharge portion, and the intermediate plate has a roughly K-shaped notch formed in a position that overlaps with the peeling portion to match the shape of the peeling portion, and the notch is composed of an arc portion located adjacent to the bead outward and a bifurcated discharge portion located between the water hole and the bolt hole and extending from the arc portion to the outer edge of the cylinder head gasket, and the discharge portion in the peeling portion and the notch of the intermediate plate is located between the water hole and the bolt hole, characterized in that the discharge portion is located between the water hole and the bolt hole. [Effects of the Invention]

[0006] With this configuration, since the peeling portion is formed and a notch is formed in the intermediate plate, a small gap is maintained between the peeling portion and the mating material. If combustion gas leaks beyond the bead to the outside, it is discharged to the outside of the cylinder head through this gap and the notch in the intermediate plate. Therefore, it is possible to suppress the intrusion of combustion gas into the water holes and effectively suppress overheating caused by combustion gas intrusion into the water holes. [Brief explanation of the drawing]

[0007] [Figure 1] A plan view showing one embodiment of the present invention. [Figure 2] Enlarged view of the main part of Figure 1. [Figure 3]A cross-sectional view along the line III-III in Figure 2. [Figure 4] A plan view of the main part showing a second embodiment of the present invention. [Figure 5] A simplified cross-sectional view along the VV line in Figure 4. [Figure 6] A plan view of the main part showing a third embodiment of the present invention. [Figure 7] A simplified cross-sectional view along the line VII-VII in Figure 6. [Figure 8] Figure 8(a) is a simplified plan view of the main parts of a conventional cylinder head gasket, and Figure 8(b) is a cross-sectional view along line bb in Figure 8(a). [Modes for carrying out the invention]

[0008] The present invention will now be described with reference to the illustrated embodiments. In Figures 1 to 3, 1 is a cylinder head gasket, and this cylinder head gasket 1 is sandwiched between the cylinder head 2 and the cylinder block 3 to maintain a seal between them. The cylinder head gasket 1 comprises a first gasket substrate 5 located on the upper side and in contact with the joint surface 2A of the cylinder head 2, a second gasket substrate 6 located on the lower side and in contact with the joint surface 3A of the cylinder block 3, and an intermediate plate 7 positioned between these two gasket substrates 5 and 6, and is constructed by laminating these together. The two gasket substrates 5 and 6 and the intermediate plate 7 that constitute the cylinder head gasket 1 are integrally connected at the required locations when laminated. The first gasket substrate 5, the second gasket substrate 6, and the intermediate plate 7 are formed in the same rectangular shape, and multiple combustion chamber holes 1A (5A to 7A) are drilled in them in accordance with the positions of the multiple cylinder bores on the cylinder block 3 side. The inner diameter of these four combustion chamber holes 1A (5A to 7A) is set to be approximately the same as the inner diameter of the cylinder bore. Furthermore, eight bolt holes 8 for inserting fastening bolts and sixteen water holes 9 for circulating cooling water are drilled at required locations on both gasket substrates 5 and 6 and the intermediate plate 7, as well as ten main bolt holes 10 for inserting fastening bolts. The combustion chamber holes 1A are formed sequentially adjacent to each other at equal intervals along the longitudinal direction of the cylinder head gasket 1. Bolt holes 8 are formed on both sides of each combustion chamber 1A, on a virtual straight line L perpendicular to the center of each combustion chamber 1A with respect to a virtual straight line connecting the centers of the four combustion chamber holes 1A. Furthermore, each pair of water holes 9 is formed on either side of the aforementioned hypothetical straight line L, and on the inward side of the bolt hole 8 (towards the combustion chamber 1A). The bolt hole 8 on one side in the short direction (upper side in Figure 1) is located on a straight line in the longitudinal direction of the cylinder head gasket 1, and the bolt hole 8 on the other side in the short direction (lower side in Figure 1) is also located on a straight line in the longitudinal direction. Similarly, the water holes 9 on both sides in the short direction are located on a straight line in the longitudinal direction. Furthermore, the main bolt holes 10 are formed at four locations along the circumferential direction of each combustion chamber hole 1A, surrounding each combustion chamber hole 1A, resulting in a total of 10 main bolt holes 10. The water holes 9 are formed in the protruding portion 1C that bulges outward from the outer edge 1B of the cylinder head gasket 1 (both gasket substrates 5 and 6 and the intermediate plate 7). Each pair of water holes 9 is located inward from the bolt holes 8 (towards the combustion chamber hole 1A). Note that the above-mentioned protruding portion 1C does not necessarily have to be provided.

[0009] The two gasket substrates 5 and 6 are manufactured from SUS301 or SUS304 of the same thickness (for example, about 0.2 mm), and the intermediate plate 7 is manufactured from SUS301 or SUS304 of about 0.08 mm thickness. The two gasket substrates 5 and 6 and the intermediate plate 7 are shaped to match the joint surfaces 2A and 3A of the cylinder head 2 and cylinder block 3, respectively, and have the same plate thickness throughout. On both gasket substrates 5 and 6, full beads 5B and 6B that endlessly surround each combustion chamber hole 1A (5A, 6A) are formed. In contrast, the entire area of the intermediate plate 7 is formed flat. The full bead 5B of the first gasket substrate 5 bulges downward toward the cylinder block 3, while the full bead 6B of the second gasket substrate 6 bulges upward toward the cylinder head 2. That is, the upper and lower full beads 5B and 6B are in symmetric positions with the intermediate plate 7 interposed therebetween, and they are formed at positions that overlap when viewed in the plan view of FIG. 1. When the completed cylinder head gasket 1 is sandwiched between the cylinder block 3 and the cylinder head 2, the full bead 5B of the first gasket substrate 5 adheres to the surface of the intermediate plate 7, and the full bead 6B of the second gasket substrate 6 adheres to the back surface of the intermediate plate 7.

[0010] At the positions of the water holes 9 in both gasket substrates 5 and 6, half beads 5C and 6C that endlessly surround each water hole 9 are formed, and at the positions of the main bolt holes 10, half beads 5D and 6D that endlessly surround each are formed. The half beads 5C and 5D of the first gasket substrate 5 have a cross-sectional shape in which the inner edge thereof recedes toward the intermediate plate 7A side from the outer edge, while the half beads 6C and 6D of the second gasket substrate 6 have a cross-sectional shape in which the inner edge thereof rises toward the intermediate plate 7A side from the outer edge. The configurations of the full beads 5B (6B) and the half beads 5C (6C), 5D (6D) are conventionally well-known. Also, on the back surface of the intermediate plate 7, an annular shim plate 11 is welded around the combustion chamber hole 7A. The thickness of the shim plate 11 is the same as or thinner than the thickness of the intermediate plate 7. Furthermore, the front surfaces (upper surfaces) and back surfaces (lower surfaces) of both gasket substrates 5 and 6 are covered with rubber coatings 12 and 13 made of rubber such as fluorine and nitrile. The thicknesses of the rubber coatings 12 and 13 are about 0.007 to 0.030 mm. Thus, since both sides of the two gasket substrates 5 and 6 are coated with the rubber coatings 12 and 13, it is possible to improve the adhesion and sealing performance between the two gasket substrates 5 and 6 and the mating members positioned above and below them.

[0011] Thus, both sides of the two gasket substrates 5 and 6 are coated with the rubber coatings 12 and 13. However, in this embodiment, instead of coating the entire areas of both sides with the rubber coatings 12 and 13, for the portions between the water holes 9 and the adjacent bolt holes 8, the rubber coatings 12 and 13 are intentionally peeled off to form peeled portions 12A and 13A. That is, the peeled portions 12A and 13A are formed in the same shape and the same dimensions at the overlapping portions in plan view on the front and back surfaces of the two gasket substrates 5 and 6, and are substantially K-shaped. The peeled portions 12A and 13A are located at the adjacent outer positions of the full beads 5B and 6B between the pair of water holes 9 and 9, and include an arc portion 12Aa (13Aa) along the circumferential direction thereof, and two linear discharge portions 12Ab (13Ab) that reach the outer edge 1B through the space between the water hole 9 and the bolt hole 8 from one end side and the other end side of the arc portion 12Aa (13Aa). The two discharge portions 12Ab (13Ab) are formed between the bolt hole 8 and the water hole 9 and in a substantially radial direction of the combustion chamber hole 1A. Thus, the arc portion 12Aa (13Aa) is located on the adjacent outer side of the full bead 5B (6B), and the inner side (combustion chamber side) ends of the two linear discharge portions 12Ab (13Ab) communicate with the arc portion 12Aa (13Aa), and the outer side ends of the discharge portions 12Ab (13Ab) are in an open state to the outer edge 1B (that is, the outside of the cylinder head gasket 1). Note that one of the two discharge portions 12Ab (13Ab) may be omitted, and the peeled portions 12A and 13A may be formed in a substantially T shape as a whole as in the second and third embodiments shown in FIGS. 4 and 6 described later. As shown in the cross-sectional view of Figure 3, when the completed cylinder head gasket 1 is interposed between the cylinder block 3 and the cylinder head 2 and tightened with bolts in the main bolt holes 10 and sub bolt holes 8, a small gap 15 is maintained between the delamination portions 12A and 13A and the mating materials above and below them in the area between the water holes 9 and the bolt holes 8. In this embodiment, since the peeling portions 12A and 13A maintain a gap 15 between them and the mating material, if the combustion gas G leaks beyond the full bead 5B (6B)) to the outside, the combustion gas G can be discharged to the outside through the gap 15 without entering the water hole 9. In other words, the peeling portions 12A and 13A function as discharge passages for guiding the leaked combustion gas G to the outside. As mentioned above, in the conventional cylinder head gasket 1 shown in Figures 8(a) and 8(b), the entire front and back surfaces of the gasket substrates 5 and 6, including the space between the water holes 9 and the bolt holes 8, were covered with rubber sheets 12 and 13. In such conventional technology, a problem has been pointed out: combustion gas G can easily penetrate into the water holes 9.

[0012] As described above, the cylinder head gasket 1 of this embodiment is equipped with peeled portions 12A and 13A where the coatings 12 and 13 have been deliberately removed. The cylinder head gasket 1 has a full bead 5B (6B) surrounding the combustion chamber holes 1A (5A, 7A, 6A), which provides protection against leakage of combustion gases G. However, if the cylinder head gasket 1 is installed on a high-horsepower racing engine, for example, the full bead 5B (6B) surrounding the combustion chamber holes 1A may not be able to maintain a complete seal. In that case, there is a risk that combustion gases G may leak outward beyond the full bead 5B (6B) and enter the water holes 9. In this case, since the cylinder gasket 1 of this embodiment has peeled portions 12A and 13A formed on the rubber coatings 12 and 13, a small gap 15 is maintained between the peeled portions 12A and 13A and the mating material. As a result, combustion gas G that leaks beyond the full beads 5B and 6B to the outside flows through the gap 15 and is discharged to the outside from the outer edge 1B of the cylinder head gasket 1. Therefore, it is possible to suppress the entry of combustion gas G that leaks outward from the full beads 5B and 6B into the water holes 9, and thereby effectively suppress the occurrence of overheating caused by combustion gas G entering the water holes 9.

[0013] Next, Figures 4 and 5 show a second embodiment of the present invention. In the first embodiment described above, peeling portions 12A and 13A were provided on both the front and back surfaces of both gasket substrates 5 and 6. In this second embodiment, however, the peeling portion 12A is formed only on the back surface of the first gasket substrate 5, while the peeling portion 13A is formed only on the front surface of the second gasket substrate 6. Furthermore, a substantially T-shaped notch 7E is formed in the intermediate plate 7, extending to the outer edge 1B. In other words, in this second embodiment, the release portion 12A formed on the back surface of the first gasket substrate 5 is roughly T-shaped, and the release portion 13A formed on the back surface of the second gasket substrate 6 is also roughly T-shaped. Furthermore, a roughly T-shaped notch 7E is formed in the intermediate plate 7 to match the shapes of the release portions 12A and 13A of both gasket substrates 5 and 6. The release portions 12A and 13A and the notch 7E of the intermediate plate 7 are formed to be the same size and shape at a position where they overlap in a plan view. The peel portion 12A of the first gasket substrate 5 is located adjacent to the full beads 5B and 6B on the outer side and consists of an arc portion 12Aa located between the two water holes 9 along its circumferential direction, and a linear discharge portion 12Ab that extends from approximately the center of the arc portion 12Aa through the water holes 9 and bolt holes 8 to the outer edge 1B. The peel portion 13A of the second gasket substrate 6 is also composed of an arc portion 13Aa and a linear discharge portion 13Ab, similar to the peel portion 12A. The notch 7E of the intermediate plate 7 is located adjacent to the full beads 5B and 6B on the outer side and consists of an arc portion 7Ea that lies between the two water holes 9 along their circumferential direction and a linear discharge portion 7Eb that extends from approximately the center of the arc portion 7Ea, passing between one of the water holes 9 and the bolt hole 8, to the outer edge 1B. In other words, the notch 7E of the intermediate plate 7 forms a roughly T-shaped gap 15 between the two gasket substrates 5 and 6 in the upper and lower positions. The first gasket substrate 5 and the rubber coating 12 have through holes 5F formed at both ends and the center of the arc-shaped portion 12Aa of the peeling portion 12A on the back surface. These three through holes 5F are in communication with the notch 7E of the intermediate plate 7. Furthermore, through holes 6F are formed in the second gasket substrate 6 and the rubber coating 13 at positions corresponding to both ends and the center of the arc portion 13Aa of the peeled portion 13A on the upper surface. These three through holes 6F are in communication with the notch portion 7E of the intermediate plate 7. In other words, in this second embodiment, the notched portion 7E of the intermediate plate 7 and the peeled portions 12A and 13A that overlap above and below it form a roughly T-shaped gap 15 in plan view. The other components are the same as in the first embodiment, and the corresponding components are, in principle, assigned the same component numbers. In this second embodiment of the cylinder head gasket 1, if combustion gas G leaks outward beyond the full beads 5B and 6B, it is discharged to the outside from the outer edge 1B of the cylinder head gasket 1 through the gap 15 formed by the notch 7E and the peeling portions 12A and 13A. Also, combustion gas G that leaks outward beyond the full bead 5B from between the first gasket substrate 5 and the cylinder head is discharged to the outside through the through hole 5F and then through the gap 15 formed by the notch 7E and the peeling portion 12A. Furthermore, combustion gas G that leaks outward beyond the full bead 6B from between the second gasket substrate 6 and the cylinder block is discharged to the outside through the through hole 6F and then through the gap 15 formed by the notch 7E and the peeling portion 13A. Therefore, it is possible to suppress the ingress of combustion gas G that leaks beyond the full beads 5B and 6B into the water holes 9. Thus, even with the configuration of this second embodiment, the same effects and advantages as those of the first embodiment can be obtained.

[0014] Next, Figures 6 and 7 show a third embodiment of the present invention. In this third embodiment, the notch portion 7E of the intermediate plate 7 has the same configuration as in the second embodiment, but the configurations of the two gasket substrates 5 and 6 are different. Specifically, a peeling portion 12A, which is approximately T-shaped in plan view, is formed on the surface (upper surface) of the first gasket substrate 5 at a position where it overlaps with the notch 7E of the intermediate plate 7, and a half bead 5G is formed on the first gasket substrate 5 along the entire approximately T-shaped contour of this peeling portion 12A. As a result, a T-shaped groove 16 is formed on the upper surface of the first gasket substrate 5, with the longitudinal cross-section of each part being V-shaped. Note that a full bead may be formed instead of the half bead 5G. Furthermore, a peeling portion 13A, which is approximately T-shaped in plan view, is formed on the back surface (bottom surface) of the second gasket substrate 6 at a position where it overlaps with the notch portion 7E of the intermediate plate 7, and a half bead 6G is formed on the back surface of the second gasket substrate 6 along the entire approximately T-shaped contour of this peeling portion 13A. As a result, a T-shaped groove 17 with an inverted V-shape in vertical cross-section is formed on the bottom surface of the second gasket substrate 6. In this third embodiment, no peeled rubber coating 12 is formed on the back surface of the first gasket substrate 5, and no peeled rubber coating is formed on the upper surface of the second gasket substrate 6. Furthermore, the through holes 5F and 6F shown in the second embodiment are not formed. Other configurations are the same as in the first embodiment, and corresponding components are generally assigned the same component numbers. In this third embodiment of the cylinder head gasket 1, if combustion gas G leaks outward beyond the full beads 5B and 6B, it is discharged to the outside from the outer edge 1B of the cylinder head gasket 1 through the gap 15 formed by the notch 7E. Also, combustion gas G that leaks outward beyond the full bead 5B from between the first gasket substrate 5 and the cylinder head is discharged to the outside through the T-groove 16 (separation portion 12A). Furthermore, combustion gas G that leaks outward beyond the full bead 6B from between the second gasket substrate 6 and the cylinder block is discharged to the outside through the T-groove 17 (separation portion 13A). Therefore, it is possible to suppress the ingress of combustion gas G that leaks outward beyond the full beads 5B and 6B into the water holes 9. Even with this configuration of the third embodiment, the same operation and effect as in the first embodiment can be obtained.

[0015] In addition, a coating material such as an elastomer may be used instead of the rubber coatings 12 and 13 in the above embodiment. Furthermore, in the first embodiment shown in Figures 1 to 3, the intermediate plate 7A is configured without a notch. However, following the second embodiment in Figure 4, in the first embodiment shown in Figures 1 to 3, a roughly K-shaped notch may be formed in the intermediate plate 7 at a position where it overlaps with the peeling portions 12A and 13A. Furthermore, although the above embodiments are described based on the premise of a cylinder head gasket 1 constructed by laminating multiple gasket substrates 5 and 6, a cylinder head gasket consisting of only a single gasket substrate may also be configured such that the above-mentioned peeling portions (12A, 13A) are provided on at least one of the rubber coatings on both the front and back surfaces of the gasket substrate. [Explanation of symbols]

[0016] 1…Cylinder head gasket 1A…Combustion chamber hole 1B...Outer edge 2...Cylinder head 3…Cylinder block 5…First gasket substrate 6...Second gasket substrate 5A, 6A...Combustion chamber opening 7…Intermediate plate 8…Bolt holes 9…Water holes 12, 13…Rubber coating 12A, 13A... peeled section

Claims

[Claim 1] A cylinder head gasket comprising at least one gasket substrate coated on at least one of its front or back surfaces, and a plurality of combustion chamber holes, water holes and bolt holes drilled at predetermined positions on the gasket substrate, wherein a bead is formed on the gasket substrate surrounding each of the combustion chamber holes, A peeled portion is formed on the gasket substrate where the coating is removed, at a position between the water holes and bolt holes, and extending from an adjacent outer position of the bead to the outer edge of the cylinder head gasket. The above-mentioned peeling portion consists of an arc-shaped portion located adjacent to the bead and outward, and a discharge portion located between the water hole and the bolt hole, extending from the arc-shaped portion to the outer edge of the cylinder head gasket. It comprises a first gasket substrate located on the upper side, a second gasket substrate located on the lower side, and an intermediate plate provided between the first gasket substrate and the second gasket substrate, and is constructed by laminating the two gasket substrates and the intermediate plate. The intermediate plate is provided with a plurality of combustion chamber holes, water holes, and bolt holes drilled at predetermined positions in the intermediate plate so as to correspond to the combustion chamber holes, water holes, and bolt holes of the first gasket substrate and the second gasket substrate described above. A coating is formed on both the front and back surfaces of the first gasket substrate and the second gasket substrate, and the peeling portion is formed on both the front and back surfaces of the first gasket substrate and the second gasket substrate. The above-mentioned peeling portion is formed in a substantially K shape by the arc portion and the bifurcated discharge portion, and the intermediate plate has a substantially K-shaped notch formed in a position that overlaps with the peeling portion, the notch is composed of an arc portion located adjacent to the bead and outward, and a bifurcated discharge portion located between the water hole and the bolt hole and extending from the arc portion to the outer edge of the cylinder head gasket, the cylinder head gasket characterized in that the discharge portion in the peeling portion and the notch of the intermediate plate are located between the water hole and the bolt hole.

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