JP2007278221A - Seal structure for internal combustion engine and gasket used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seal structure for an internal combustion engine and a gasket used for the same materializing a means capable of inhibiting corrosion of a cylinder head by water in an exhaust system of the engine or the like with a simple structure. <P>SOLUTION: A sleeve part 24 extending toward an inner part of an exhaust port 14 is formed as one unit with the gasket 2 put between an exhaust manifold mounting surface 13 of the cylinder head 1 and a flange 33 of the exhaust manifold 3. Even if condensed water stays near a connection part of the cylinder head 1 and the exhaust manifold 3, the cylinder head 1 is prevented from touching the condensed water by the sleeve part 24 of the gasket 2. Consequently, corrosion of the cylinder head 1 can be prevented. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a seal structure applied to, for example, an exhaust system of an internal combustion engine and a gasket used for the seal structure. In particular, the present invention relates to measures for preventing corrosion of the cylinder head.

  Conventionally, for example, as an exhaust system configuration of an automobile engine, an exhaust manifold is connected to a cylinder head, and exhaust gas in a combustion chamber is discharged toward an exhaust pipe. Specifically, as disclosed in, for example, Patent Document 1 and Patent Document 2 below, a flange is provided at the upstream end of the exhaust manifold, and this flange and the exhaust port end surface of the cylinder head are provided. An exhaust manifold is attached to the cylinder head in a state where a gasket is interposed between the exhaust port and the end face where the exhaust port opens. This gasket prevents leakage of exhaust gas from between the exhaust manifold and the cylinder head.

  FIG. 9 is a cross-sectional view showing the connection portion between the exhaust manifold a and the cylinder head b and the configuration around it. Specifically, it is a longitudinal sectional view of a connecting portion between one of a plurality of branch pipes c constituting the exhaust manifold a and the cylinder head b.

  As shown in this figure, a flange d is welded to the outer peripheral portion of the upstream end of the branch pipe c of the exhaust manifold a, and this flange d is connected to the end surface of the cylinder head b by means of bolting or the like via a gasket e. Is attached by.

  Further, at the connection portion between the exhaust manifold a and the cylinder head b, exhaust gas (the flow direction of the exhaust gas is indicated by a solid arrow in the drawing) is supplied from the exhaust port f of the cylinder head b to the branch pipe c. In order to reduce the pressure loss when flowing into the pipe, the inner diameter of the branch pipe c is set larger than the inner diameter of the exhaust port f.

  For this reason, as shown in FIG. 9, in the structure in which the branch pipe c is connected to the cylinder head b from obliquely above, a slight step is generated at the boundary between the exhaust port f and the branch pipe c. When the moisture contained in the exhaust gas is condensed inside the branch pipe c, the condensed water may accumulate in the step portion (see g indicated by a virtual line in the figure). In this portion, the inner diameter dimension of the opening of the gasket e is set to be substantially the same as the inner diameter dimension of the branch pipe c and larger than the inner diameter dimension of the exhaust port f. When the condensed water g stays in contact with the cylinder head b for a long period of time, the cylinder head b may be corroded. When the cylinder head b is made of an aluminum alloy or cast iron, there is a great concern about corrosion.

  If the cylinder head b is corroded, the sealing performance of the connecting portion between the cylinder head b and the exhaust manifold a is deteriorated, causing leakage of exhaust gas and accompanying oil leakage in the exhaust gas. There is a possibility.

In addition, the concern of the corrosion of the cylinder head due to the stagnation of the condensed water is not only the connection position of the exhaust manifold a (branch pipe c) to the cylinder head b but also the connection of EGR (Exhaust Gas Recirculation) piping to the cylinder head. In an engine that performs air injection to an exhaust system, there is a possibility that the same occurs at the connection point of the air injection pipe to the cylinder head.
JP-A-8-232759 JP 2005-30247 A

  As one of the means for solving the concern of the corrosion of the cylinder head due to the condensate stay as described above, the stepped portion (the step formed at the boundary portion between the exhaust port f and the branch pipe c) is not formed. Although it is conceivable to set the inner diameter dimension of the branch pipe c (for example, to reduce the inner diameter dimension of the branch pipe c), this may increase the pressure loss of the exhaust gas, leading to a decrease in engine output. It will end up.

  Further, even if the stepped portion exists, the branch pipe c is connected to the cylinder head b from obliquely below so that water does not stay in the stepped portion and flows down from the exhaust manifold toward the exhaust pipe. Although a configuration is conceivable, this is not preferable because it greatly restricts the design of the cylinder head b and the piping shape of the exhaust manifold a.

  The present invention has been made in view of the above points, and an object of the present invention is to realize means capable of suppressing corrosion of the cylinder head by water in an engine exhaust system or the like with a simple configuration. An internal combustion engine seal structure and a gasket used for the seal structure are provided.

-Principle of solving the problem-
The solution principle of the present invention taken to achieve the above object is to partially cover the cylinder head by extending a part of the gasket attached to the cylinder head toward an exhaust system flow path such as an exhaust port. Thus, the extension portion can prevent contact between the cylinder head and water.

-Solution-
Specifically, the present invention is premised on a seal structure at a location where a piping member is connected to an open end face of an exhaust system flow path formed in a cylinder head of an internal combustion engine. For this seal structure, a gasket is interposed between the open end face of the exhaust system flow path in the cylinder head and the piping member, and a head protection portion extending toward the inside of the exhaust system flow path is provided on the gasket. The head protection portion covers the peripheral portion of the open end surface of the exhaust system flow path.

  With this specific matter, when a piping member (for example, an exhaust manifold or EGR piping) is connected to the cylinder head via a gasket, the head protection portion of the gasket covers the periphery of the open end surface of the exhaust system flow path. Become. For this reason, even if condensed water is generated inside the piping member and stays in the vicinity of the connecting portion between the cylinder head and the piping member, the head protecting portion prevents the condensed water from contacting the cylinder head. That is, the gasket has a function of preventing the cylinder head from coming into contact with water. Therefore, it is possible to obtain a configuration that prevents corrosion of the cylinder head without changing (design change) the inner diameter dimension of the piping member and the connecting direction of the piping member to the cylinder head.

  Further, when the gasket is attached to the cylinder head, the gasket head protection part can be inserted into the exhaust system flow path of the cylinder head. That is, the gasket can be temporarily assembled to the cylinder head before the piping member is attached. For this reason, it is not necessary to carry out attachment work such as bolting while holding the gasket at the time of attachment of the piping member, or to provide a stud bolt on the cylinder head, and workability is improved. Furthermore, since the gasket positioning function with respect to the cylinder head is exhibited in a state where the head protection portion is inserted into the exhaust system flow path of the cylinder head, there is no deviation in the gasket mounting position. For this reason, it is not necessary to preliminarily design the seal width (the area of the seal portion obtained by the gasket) in consideration of the gasket displacement, the gasket design becomes easier and the gasket is reduced by reducing the seal width. Can be reduced in size and cost.

  Examples of the configuration when the present invention is applied to a connecting portion between a cylinder head and an exhaust manifold of an internal combustion engine include the following. That is, it is assumed that the seal structure is at the connection position of the exhaust manifold to the open end face of the exhaust port formed in the cylinder head of the internal combustion engine. For this seal structure, a gasket is interposed between the open end face of the exhaust port and the exhaust manifold, and a head protection portion extending toward the inside of the exhaust port is provided in the gasket, and the exhaust port is provided by the head protection portion. It is set as the structure which covers the peripheral part of the open side end surface.

  Also by this specific matter, the same action as in the case of the above-described solution can be obtained. That is, even if condensed water is generated and stays inside the exhaust manifold, the condensed water is prevented from contacting the cylinder head by the head protection portion extending from the gasket. For this reason, it becomes possible to prevent corrosion of the cylinder head. In addition, when attaching the gasket to the cylinder head, it can be done by inserting the gasket head protection part into the exhaust port of the cylinder head, so the attachment work is easy and the seal width of the gasket is designed to be large beforehand. Therefore, the design is easy and the cost can be reduced.

  Specific examples of the shape of the gasket include the following. That is, a lip portion that protrudes toward the inner peripheral surface of the exhaust system flow path (exhaust port) is formed in the head protection portion of the gasket over the circumferential direction of the head protection portion, and the lip portion is formed in the exhaust system flow path The gasket is assembled to the cylinder head with the inner surface of the exhaust port) pressed.

  According to this particular matter, the gap between the head protection part of the gasket and the inner peripheral surface of the exhaust system flow path is sealed by the lip part, and water and oil flow into the gap between the two. Can be prevented. Further, since the gasket is assembled to the cylinder head in a state where the lip portion presses the inner surface of the exhaust system flow path, it is possible to obtain a high accuracy of the gasket assembling position with respect to the cylinder head.

  Specific examples of the shape of the head protection unit include the following two types. First, the head protection part is formed over the entire circumference along the inner surface of the exhaust system flow path (exhaust port). In addition, the head protection portion is formed only in the lower half region of the periphery along the exhaust system flow path (exhaust port) inner surface.

  In particular, in the case where the head protection part is formed only in the lower half of the periphery along the exhaust system flow path inner surface, the necessary minimum area (the above condensed water is between the cylinder head and the piping member (exhaust manifold)). Since it accumulates below the connection location, the protection location required to prevent corrosion of the cylinder head is only in the lower half area), which reduces the cost of the gasket. Connected.

  Moreover, the gasket used for the sealing structure of any one of the above-described solutions is also within the scope of the technical idea of the present invention. That is, a gasket main body having an opening substantially matching the opening of the exhaust system flow path (exhaust port) and sandwiched between the cylinder head and the piping member (exhaust manifold), and an edge of the opening of the gasket main body And a head protection part extending toward the inside of the exhaust system flow path (exhaust port).

  In the present invention, even if condensed water is generated inside the piping member communicating with the exhaust system flow path by extending a part of the gasket attached to the cylinder head toward the exhaust system flow path such as the exhaust port. The extension portion (head protection portion) prevents contact between the cylinder head and the condensed water. Therefore, it is possible to prevent the cylinder head from being corroded by water without changing the inner diameter of the piping member or changing the connecting direction of the piping member with respect to the cylinder head. Can be achieved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. This embodiment demonstrates the case where this invention is applied to the connection location of the cylinder head and exhaust manifold in the exhaust system of a motor vehicle engine.

(First embodiment)
FIG. 1 is an exploded perspective view of a cylinder head 1, a gasket 2, and an exhaust manifold (a piping member in the present invention) 3 in the present embodiment. As shown in FIG. 1, the engine according to this embodiment is a four-cylinder engine, and exhaust port openings 11, 11,... Are formed at four locations on the side surface of the cylinder head 1. The cylinder head 1 is made of an aluminum alloy, and a cylinder block is attached to the lower part and a head cover is attached to the upper part.

  The exhaust manifold 3 is made of a stainless steel plate and includes four branch pipes 31, 31,... Corresponding to each cylinder, and a junction pipe 32 that joins the downstream ends of the branch pipes 31, 31,. . Further, a flange 33 is integrally attached to upstream ends of the branch pipes 31, 31,... By means such as welding. The flange 33 is attached to the side surface of the cylinder head 1 (the side surface on which the exhaust port openings 11, 11,... Are formed: hereinafter referred to as the exhaust manifold mounting surface 13) by bolting or the like, The bolt insertion holes 34, 34,... Are formed corresponding to the bolt holes 12, 12,.

  The gasket 2 is sandwiched between the exhaust manifold mounting surface 13 of the cylinder head 1 and the flange 33 of the exhaust manifold 3 to prevent leakage of exhaust gas from between the cylinder head 1 and the exhaust manifold 3. Functions as a member. The gasket 2 is configured by laminating a plurality of (for example, two) plate materials made of metal (for example, stainless steel), and a bead is provided at a position corresponding to the peripheral portion of the exhaust port openings 11, 11,. When the bent portion is formed and is sandwiched between the cylinder head 1 and the exhaust manifold 3, the bead is compressed and deformed to increase the degree of adhesion, thereby obtaining high sealing performance. Yes.

  Further, the gasket 2 has exhaust openings 21, 21,... Formed at four positions corresponding to the exhaust port openings 11, 11,... And the bolt holes 12, 12,. Are formed corresponding to the bolt insertion holes 22, 22,. The feature of the present embodiment is the configuration of the portion where the exhaust openings 21, 21,.

  FIG. 2 is a perspective view showing a surface of the gasket 2 on the side in contact with the exhaust manifold mounting surface 13. FIG. 3 is a cross-sectional view showing the connection portion between the exhaust manifold 3 and the cylinder head 1 and the configuration around it. Specifically, it is a longitudinal sectional view of a connection portion of one branch pipe 31 to the cylinder head 1.

  As shown in this figure, the flange 33 welded to the outer peripheral portion of the upstream end of the branch pipe 31 of the exhaust manifold 3 is attached to the exhaust manifold attachment surface 13 of the cylinder head 1 by means such as bolting via the gasket 2. It has been.

  Further, in the connection portion between the exhaust manifold 3 and the cylinder head 1, in order to reduce the pressure loss when the exhaust gas flows into the branch pipe 31 from the exhaust port (exhaust system flow path) 14 of the cylinder head 1, The inner diameter of the branch pipe 31 is set slightly larger than the inner diameter of the exhaust port 14.

  As a feature of the gasket 2, the opening shape of the exhaust opening 21 substantially matches the opening shape of the exhaust port 14 of the cylinder head 1, that is, the opening shape of the exhaust port opening 11, and from the opening edge thereof. A substantially cylindrical sleeve portion 24 extending toward the inside of the exhaust port 14 is integrally formed. That is, the gasket 2 is formed from a substantially flat gasket main body 23 sandwiched between the cylinder head 1 and the exhaust manifold 3, and from the peripheral portions of the exhaust openings 21, 21, ... in the gasket main body 23. .. Are provided with four substantially cylindrical sleeve portions (head protection portions) 24, 24,... Extending toward the inside of the exhaust port 14. The projecting dimension of the sleeve portion 24 from the gasket main body portion 23 is set to about 20 mm, for example. This dimension is not limited to this and can be set as appropriate. Further, the gasket main body 23 sandwiched between the cylinder head 1 and the exhaust manifold 3 has a structure in which metal plates are laminated as described above, and the sleeve 24 is similarly laminated with a metal plate. (The laminated structure is omitted in each figure). Since the sleeve portion 24 is not a portion sandwiched between the cylinder head 1 and the exhaust manifold 3, it does not necessarily have a laminated structure.

  More specifically, as the shape of the sleeve portion 24, a lip portion 25 whose diameter is expanded in the outer circumferential direction is formed over the entire circumferential direction at the tip portion, and the outer edge of the lip portion 25 is the exhaust port 14. It is in contact with the inner surface of. The outer diameter of the lip portion 25 is equal to or slightly larger than the inner diameter of the exhaust port 14, and the sleeve portion 24 is inserted into the exhaust port 14 when the gasket 2 is assembled to the cylinder head 1. Then, the outer peripheral surface of the lip portion 25 presses the inner peripheral surface of the exhaust port 14, so that the sealing performance between the sleeve portion 24 and the inner peripheral surface of the exhaust port 14 is ensured. It has become.

  Next, an operation for attaching the exhaust manifold 3 to the cylinder head 1 will be described. First, the gasket 2 is assembled to the cylinder head 1. This operation is performed by fitting the sleeve portions 24, 24,... Formed in the gasket 2 into the corresponding exhaust ports 14, 14,. As a result, the gasket 2 is temporarily assembled to the exhaust manifold mounting surface 13 of the cylinder head 1. In this state, the sleeve portions 24, 24,... Are fitted into the exhaust ports 14, 14,..., So that the gasket 2 is positioned with respect to the cylinder head 1, and the gasket 2 is displaced. It is assembled to the cylinder head 1 without doing so.

  Thereafter, the operation of assembling the exhaust manifold 3 is started. In this operation, the flange 33 of the exhaust manifold 3 is overlaid on the exhaust manifold mounting surface 13 (actually overlaid with the gasket 2 interposed), the bolt insertion hole 34 of the exhaust manifold 3, the bolt of the gasket 2 The exhaust manifold 3 is assembled to the cylinder head 1 by inserting a bolt through the insertion hole 22 and screwing the bolt into the bolt hole 12 of the cylinder head 1. As a result, the exhaust manifold 3 is attached to the cylinder head 1 with the gasket 2 interposed therebetween, and leakage of exhaust gas from between the cylinder head 1 and the exhaust manifold 3 is prevented by the gasket 2.

  When the exhaust manifold 3 is assembled to the cylinder head 1 with the gasket 2 sandwiched in this manner, the sleeve portion 24 of the gasket 2 extends from the exhaust manifold mounting surface 13 of the cylinder head 1 to the exhaust port 14. Will be covered. Therefore, even if condensed water is generated inside the branch pipe 31 and stays in the vicinity of the connecting portion between the cylinder head 1 and the branch pipe 31 (see W indicated by a phantom line in FIG. 3), the condensed water W is transferred to the cylinder head. 1 is never touched. That is, the gasket 2 can have a function of preventing the cylinder head 1 from coming into contact with the water W. Therefore, corrosion of the cylinder head 1 can be prevented without changing (design change) the inner diameter dimension of the branch pipe 31 and the connection direction of the exhaust manifold 3 to the cylinder head 1, and the engine life can be extended. it can.

  Further, as described above, according to the gasket 2 in the present embodiment, the gasket 2 can be temporarily assembled to the cylinder head 1 before the exhaust manifold 3 is attached. Conventionally, when attaching the exhaust manifold, holding the gasket so that it is not misaligned, the bolt is fixed, or a cylinder head is pre-installed with stud bolts, and the gasket and exhaust manifold are attached to the stud bolts. Although it was necessary to assemble, according to the present embodiment, these operations are unnecessary, and workability is good. Furthermore, since the sleeve portion 24 is inserted into the exhaust port 14 of the cylinder head 1, the gasket 2 is positioned with respect to the cylinder head 1, so that the mounting position of the gasket 2 does not shift. For this reason, it is not necessary to preliminarily design the seal width (the area of the seal portion obtained by the gasket 2: the area of the gasket main body portion 23) in consideration of the displacement of the gasket 2, and the design of the gasket 2 is eliminated. The gasket 2 can be reduced in size and cost by reducing the seal width.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the present embodiment, the configuration of the gasket is different from that of the first embodiment described above. Since the other structure is the same as that of 1st Embodiment, only the structure of a gasket is demonstrated here.

  FIG. 4 is a diagram corresponding to FIG. 1 in the present embodiment. FIG. 5 is a perspective view showing one gasket 2A in the present embodiment.

  As shown in these drawings, the gasket 2A according to this embodiment is individually manufactured for each cylinder. That is, since the engine according to the present embodiment has four cylinders, four gaskets 2A, 2A,. Since the individual gaskets 2A, 2A,... Have the same shape, only one gasket 2A will be described here.

  As shown in FIG. 5, the gasket 2A in the present embodiment has an exhaust gas from a gasket main body 23A sandwiched between the cylinder head 1 and the exhaust manifold 3, and a peripheral edge of the exhaust opening 21A in the gasket main body 23A. The sleeve portion 24 </ b> A extends toward the inside of the port 14. Further, a lip portion 25A having a diameter increased in the outer peripheral side direction is formed at the distal end portion of the sleeve portion 24A over the entire circumferential direction. Further, bolt insertion holes 22A and 22A for attaching the gasket 2A to the exhaust manifold attachment surface 13 of the cylinder head 1 are formed in the gasket body portion 23A.

  Further, the bolt holes 12 formed in the exhaust manifold mounting surface 13 of the cylinder head 1 according to the present embodiment and the bolt insertion holes 34 formed in the flange 33 of the exhaust manifold 3 are the bolts of the gaskets 2A, 2A,. It is also formed at a position corresponding to the insertion holes 22A and 22A.

  As an operation of attaching the exhaust manifold 3 to the cylinder head 1 in the present embodiment, first, an assembly operation of the four gaskets 2A, 2A,. This operation is performed by fitting the sleeve portions 24A formed on the gasket 2A into the exhaust ports 14, respectively. As a result, the gaskets 2A, 2A,... Are temporarily attached to the exhaust manifold attachment surface 13 of the cylinder head 1, respectively. Further, as an assembly posture of the gasket 2 </ b> A with respect to the exhaust manifold attachment surface 13, the bolt insertion hole 22 </ b> A formed in the gasket main body portion 23 </ b> A overlaps the bolt hole 12 of the exhaust manifold attachment surface 13.

  Thereafter, the flange 33 of the exhaust manifold 3 is superimposed on the exhaust manifold mounting surface 13 (actually, with the gaskets 2A, 2A,... Interposed), and bolts are inserted into the bolt insertion holes 34 of the exhaust manifold 3. The exhaust manifold 3 is assembled to the cylinder head 1 by inserting and screwing bolts into the bolt holes 12 of the cylinder head 1. Thus, the exhaust manifold 3 is attached to the cylinder head 1 with the gasket 2 interposed.

  Also in the present embodiment, as in the case of the first embodiment, even if condensed water is generated and stays in the branch pipe 31, the sleeve portion 24A prevents the condensed water from contacting the cylinder head 1. Therefore, corrosion of the cylinder head 1 can be prevented. Further, when the gaskets 2A, 2A,... Are attached to the cylinder head 1, since the sleeve portion 24A of the gasket 2A can be inserted into the exhaust port 14 of the cylinder head 1, the attaching operation is easy and the gasket Since it is not necessary to design a large seal width in advance, the design is easy and the cost can be reduced.

(Third embodiment)
Next, a third embodiment of the present invention will be described. This embodiment is also different from the first embodiment described above in the configuration of the gasket. Since the other structure is the same as that of 1st Embodiment, only the structure of a gasket is demonstrated here.

  FIG. 6 is a diagram corresponding to FIG. 2 in the present embodiment. FIG. 7 is a diagram corresponding to FIG. 3 in the present embodiment.

  As shown in these drawings, in the gasket 2 according to the present embodiment, the sleeve portion 24 is formed only in the substantially lower half region of the periphery along the inner surface of the exhaust port 14. This is because the condensed water W accumulates below the connecting portion between the cylinder head 1 and the exhaust manifold 3, and it is sufficient if the contact between the cylinder head 1 and the water W can be avoided only at the lower portion. The sleeve portion 24 is formed in the minimum necessary area. Other configurations are the same as those of the first embodiment described above.

  According to the present embodiment, the cylinder head 1 can be prevented from being corroded while the cost of the gasket 2 is reduced by forming the sleeve portion 24 in the minimum necessary region, and the engine life is extended. be able to.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described. In the present embodiment, the configuration of the gasket is different from that of the second embodiment described above. Since the other configuration is the same as that of the second embodiment, only the configuration of the gasket will be described here.

  FIG. 8 is a diagram corresponding to FIG. 5 in the present embodiment. As shown in this figure, also in the gasket 2 </ b> A in the present embodiment, the sleeve portion 24 </ b> A is formed only in the substantially lower half region of the periphery along the inner surface of the exhaust port 14. The reason is the same as in the case of the third embodiment described above, and the sleeve portion 24A is formed in the minimum necessary region. Other configurations are the same as those of the second embodiment described above.

  According to the present embodiment, the cylinder head 1 can be prevented from being corroded while the cost of the gasket 2A is reduced by forming the sleeve portion 24A in the minimum necessary region, and the engine life can be extended. Can do.

-Other embodiments-
Each embodiment described above demonstrated the case where this invention was applied to the connection location of the cylinder head 1 and the exhaust manifold 3 in the exhaust system of a motor vehicle engine. The present invention is not limited to this, and can also be applied to a connection portion between the cylinder head 1 and the EGR pipe, or a connection portion between the cylinder head 1 and the air injection pipe in an engine that performs air injection to the exhaust system. . That is, when the moisture in the EGR gas condenses at the connection portion between the cylinder head 1 and the EGR pipe, or when a situation occurs in which the exhaust gas flows back through the air injection pipe, the moisture in the exhaust gas becomes the cylinder head 1. It is possible to cope with the case where condensation occurs at the connection point between the air injection pipe and the air injection pipe.

  Moreover, although the engine which concerns on each embodiment mentioned above was a 4-cylinder thing, it is not restricted to this, It can apply also to an engine with the number of cylinders of 3 cylinders or less, and an engine of 5 cylinders or more. In this case, in the first embodiment and the third embodiment, the number of exhaust openings 21, 21,... Corresponding to the number of cylinders is formed in the gasket 2, so that the individual exhaust openings 21, Corresponding to 21,..., Sleeve portions 24, 24,. Moreover, in the said 2nd Embodiment and 4th Embodiment, the number of gaskets 2A, 2A, ... according to the number of cylinders is attached.

  Further, the sleeve portion 24 of the gasket 2 in each of the above embodiments is provided with the lip portion 25. However, the present invention is not limited to this, and the outer peripheral surface of the sleeve portion 24 is not substantially provided with the lip portion 25. The entire configuration may be in contact with the inner peripheral surface of the exhaust port 14.

  Further, in each of the above embodiments, the cylinder head 1 is made of an aluminum alloy, but the present invention is not limited to this, and may be applied to a cast iron cylinder head.

It is a disassembled perspective view of the cylinder head in the 1st embodiment, a gasket, and an exhaust manifold. It is a perspective view which shows the gasket in 1st Embodiment. It is sectional drawing which shows the connection part of the exhaust manifold and cylinder head in 1st Embodiment, and the structure of the periphery. It is a disassembled perspective view of the cylinder head, a gasket, and an exhaust manifold in 2nd Embodiment. It is a perspective view of the gasket in 2nd Embodiment. It is a perspective view which shows the gasket in 3rd Embodiment. It is sectional drawing which shows the connection part of the exhaust manifold and cylinder head in 3rd Embodiment, and the structure of the periphery. It is a perspective view of the gasket in 4th Embodiment. It is sectional drawing which shows the connection part of the exhaust manifold and cylinder head in a prior art example, and the structure of the periphery.

Explanation of symbols

1 Cylinder head 11 Exhaust port opening 13 Exhaust manifold mounting surface (open side end surface)
14 Exhaust port (exhaust system flow path)
2,2A Gaskets 21, 21A Exhaust openings 23, 23A Gasket body parts 24, 24A Sleeve parts (head protection parts)
25,25A Lip part 3 Exhaust manifold (pipe member)

Claims (6)

A seal structure at a connection point of a piping member to an open side end surface of an exhaust system passage formed in a cylinder head of an internal combustion engine,
A gasket is interposed between the open end face of the exhaust system flow path in the cylinder head and the piping member, and a head protection portion extending toward the inside of the exhaust system flow path is provided on the gasket. A seal structure for an internal combustion engine, characterized in that the periphery of the open side end face of the exhaust system flow path is covered by the head protection part. A seal structure at a connection location of an exhaust manifold to an open end surface of an exhaust port formed in a cylinder head of an internal combustion engine,
A gasket is interposed between the open end face of the exhaust port and the exhaust manifold. The gasket is provided with a head protection portion extending toward the inside of the exhaust port. A seal structure for an internal combustion engine, wherein a peripheral portion of an open end face of a port is covered. In the internal combustion engine seal structure according to claim 1,
A lip portion that protrudes toward the inner peripheral surface of the exhaust system flow path is formed on the gasket head protection portion over the circumferential direction of the head protection portion, and this lip portion presses the inner surface of the exhaust system flow channel. A seal structure for an internal combustion engine, characterized in that the gasket is assembled to the cylinder head in a state of being made. In the internal combustion engine seal structure according to claim 1 or 3,
A seal structure for an internal combustion engine, wherein the head protection part is formed over the entire circumference along the inner surface of the exhaust system flow path. In the internal combustion engine seal structure according to claim 1 or 3,
2. A seal structure for an internal combustion engine, wherein the head protection portion is formed only in a substantially lower half region of the periphery along the exhaust system flow path inner surface.   A gasket used for a seal structure of an internal combustion engine according to any one of claims 1 to 3, wherein the gasket has an opening substantially coinciding with an opening of an exhaust system flow path, and a cylinder head and a pipe A gasket comprising: a gasket main body sandwiched between members; and a head protection portion extending from an edge of an opening of the gasket main body toward the inside of the exhaust system flow path.

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