JP2591062Y2 - Exhaust manifold mounting structure - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust manifold mounting structure in which an exhaust manifold is mounted on an end face of a cylinder head or an exhaust pipe forming an exhaust passage via a gasket.

[0002]

2. Description of the Related Art At present, most of exhaust manifolds used in engines are manufactured by casting cast iron in order to improve heat resistance and to reduce manufacturing costs. Although the heat resistance of cast iron is high, the heat conduction from the combustion chamber is large because the heat conduction is relatively good. Today, many engines are equipped with a turbocharger, but the exhaust manifold made of cast iron is very heavy, hinders engine weight reduction, has a large amount of heat dissipation, and is not desirable for energy recovery. It is. Therefore, in order to reduce the weight of the exhaust manifold, a liner located on the inner surface of the aluminum alloy made of ceramics having a low thermal conductivity has been developed to be made of an aluminum alloy and to constitute a heat shielding structure.

FIG. 2 shows an exhaust manifold mounting structure as described above, for example. The mounting structure of the exhaust manifold is an exhaust passage 17 of a multi-cylinder engine.
The flange portion 1 of the exhaust manifold 2 is provided on the end face 13 of the cylinder head 1 (or the exhaust pipe forming the exhaust passage).
2 are connected via a gasket 4. The exhaust manifold 2 includes a liner 5 made of ceramics having a low thermal conductivity and serving as an inner wall surface forming an exhaust passage 18, and a liner 5.
And an outer member 7 made of a metal disposed by casting with a heat insulating layer 6 interposed therebetween. Exhaust manifold 2
The gasket 4 is attached to the cylinder head 1 such that the end surface 20 of the flange portion 12 of the outer member 7 contacts the entire surface of the gasket 4 on the exhaust manifold 2 side. The end outer peripheral surface 14 of the liner 5 contacts the inner wall surface 15 of the flange portion 12 of the outer member 7, and the end surface 16 of the liner 5 contacts the ring-shaped protrusion 10 of the flange portion 12.

Conventionally, as an exhaust gas heat insulating device for an internal combustion engine, there is one disclosed in Japanese Utility Model Laid-Open No. 57-47710. The exhaust gas heat insulating device of the internal combustion engine is provided with a heat insulating material co-cast on the inner surface of the exhaust gas passing member of the internal combustion engine with a supercharger except for both ends of the exhaust gas inlet and outlet when casting the main body of the member. It is.

[0005] As a heat insulating structure, Japanese Utility Model Laid-Open No. 54-1
There is one disclosed in Japanese Patent Publication No. 00115. In the heat insulating structure, a molded body of unit mesh metal is fitted to the outer surfaces of both ends of the hollow body made of ceramic, and the metal is cast through the molded body so as to form an air chamber between the molded bodies. It is something.

[0006]

By the way, the exhaust gas discharged from each cylinder of the multi-cylinder engine merges into the collecting portion through the branch portion and the bent portion of the exhaust manifold, and from the collecting portion to the exhaust pipe. However, the flow rate of the exhaust gas is larger than that of the branch part because the exhaust gas merges at the collecting part, and the flow velocity is also faster. At the collecting part, the flow rate is higher by about 30 to 50 ° C. than that of the branch part. In addition, in order to reduce the amount of heat radiation from the combustion chamber and effectively apply the heat energy of the exhaust gas to the turbocharger provided in the engine, the exhaust gas is made of ceramics having a very low thermal conductivity and a small specific gravity. A manufacturing method in which the manifold liner is cast with a metal such as an aluminum alloy is considered.

In particular, an outer member 7 is formed by casting a liner 5 made of a ceramic such as aluminum titanate as shown in FIG. 2 with metal with a heat insulating layer 6 such as air or heat insulating material interposed therebetween. For the exhaust manifold 2,
In order to fix the liner 5, the open end, that is, the end face 16 is in direct contact with the protruding portion 10 of the metal flange portion 12, and because of thermal stress generated by heat shrinkage during solidification of the metal after the casting step. In addition, there is a problem that the liner 5 is damaged such as cracks, cracks, cracks and the like. Further, the exhaust gas heat insulating device for an internal combustion engine disclosed in Japanese Utility Model Laid-Open No. 57-47710 has the same problem.

The heat insulating structure disclosed in Japanese Utility Model Application Laid-Open No. 54-100115 cited above uses a unit mesh metal having a low modulus of elasticity to relieve the ceramic hollow body. Is transmitted, since the unit mesh metal is supported, repeated relative movement due to vibration between the cast metal of the outer member and the ceramic hollow body becomes severe, and a problem occurs in fixing the ceramic hollow body. There is a problem that the ceramic hollow body is damaged.

In addition, when the engine is configured as a heat shielding structure, and the exhaust manifold in the exhaust system is configured as a heat shielding structure so that the exhaust gas energy can be efficiently recovered by a turbocharger or an energy recovery device, the exhaust gas may be exhausted. When both ends of the manifold are attached to the metal cylinder head or other parts of the metal exhaust pipe, a gap exists between the end face of the low thermal expansion coefficient liner and the end face of the metal part. The outer member is exposed to the combustion gas, and a heat flow is generated to the outer member through the exposed surface, so that there is a problem that heat energy of the exhaust gas is radiated to the outside.

An object of the present invention is to solve the above-mentioned problems, and to provide a liner made of a ceramic such as aluminum titanate having a very low thermal conductivity and a small specific gravity for forming an exhaust passage, and the liner. An exhaust manifold comprising a metal outer member disposed on the outer periphery of the liner via a heat insulating layer, and an exhaust manifold mounting structure for mounting the end face of a cylinder head or an exhaust pipe via a gasket; By interposing a metal ring with a high elastic modulus and a high melting point on the outer periphery, it is possible to prevent the ceramic liner from being damaged by thermal stress generated by thermal contraction of the metal when casting the outer member that surrounds the outer periphery of the liner. In addition, the exhaust manifold can fix the liner radially and axially firmly without becoming unstable due to vibration etc. To provide a de mounting structure.

[0011]

The present invention has the following configuration to achieve the above object. That is, the present invention provides an exhaust manifold mounting structure in which an exhaust manifold is connected to a component forming an exhaust passage via a gasket, wherein the exhaust manifold has a low thermal conductivity ceramic liner forming an exhaust passage, and an end of the liner. A heat insulating layer disposed on the outer periphery except for a portion, a metal ring disposed on an outer periphery and an end surface of the liner spaced apart from the heat insulating layer, and a metal ring disposed on the outer periphery of the ring, the heat insulating layer, and the liner. The ring is made of a metal having a higher melting point and a higher elastic modulus than the metal of the outer member, and relates to a mounting structure for an exhaust manifold.

Further, in the exhaust manifold mounting structure, the exhaust manifold is fixed to the component in a state where an end surface of the flange and a ring constituting the mounting surface of the outer member abut on the gasket. is there.

In the exhaust manifold mounting structure, a ring-shaped protruding portion extending inward in a radial direction of the outer member abutting on an outer peripheral surface of the liner in which the ring and the heat insulating layer are separated is provided on the liner. The radial direction is fixed, and the ring fixes the axial direction of the liner.

[0014]

[Action] The mounting structure of the exhaust manifold according to the present invention is as follows.
The configuration described above operates as follows. In this exhaust manifold mounting structure, the exhaust passage is formed of a low thermal conductivity ceramic liner, and a metal ring is arranged on the outer periphery and the end surface of the liner so as to be spaced apart from the heat insulating layer on the outer periphery of the liner. A metal outer member was arranged by casting on the outer periphery of the ring, the heat insulating layer, and the liner, and the ring was made of a metal having a higher melting point and a higher elastic modulus than the metal of the outer member. When the outer member is formed by casting a metal in a state where the ring is disposed on the end surface, a displacement amount due to heat shrinkage of the metal of the ring is smaller than a case where the outer member directly contacts, The difference in thermal expansion between the ring and the liner is reduced, and as a result, the thermal stress applied to the liner is reduced, and damage to the liner can be prevented.

The end face of the liner abuts on the ring, and the axial direction, that is, the longitudinal direction of the liner is fixed by the ring. The ring-shaped protrusion extending inward in the radial direction of the outer member is provided on the liner. The outer diameter of the liner is fixed by the frictional force of the cast metal portion of the protruding portion of the outer member by contacting the outer peripheral surface of the end portion of the liner. Fixed stably.

In this exhaust manifold mounting structure,
When the outer member is made of Al, the metal ring is preferably made of Fc or a ceramic such as Al ₂ O ₃ , and when the outer member is made of Fc, the metal ring is made of a metal. The ring is preferably made of a ceramic such as Al ₂ O ₃ .

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the exhaust manifold mounting structure according to the present invention will be described below with reference to FIG. FIG. 1 is a sectional view showing an embodiment of an exhaust manifold mounting structure according to the present invention. This embodiment has the same configuration as the conventional exhaust manifold mounting structure shown in FIG. 2 except that a metal ring is provided on the mounting portion. The description of the operation will be omitted.

FIG. 1 shows an exhaust manifold 2 attached to parts of a multi-cylinder engine (only one cylinder is shown in the figure) so as to communicate with a cylinder head 1 or an exhaust passage 17 formed in an exhaust pipe. I have. The exhaust manifold 2 is
A liner 5 forming an exhaust passage 18, an outer member 7 made of metal disposed outside the liner 5, a heat insulating layer 6 interposed between the liner 5 and the outer member 7, and an end 11 of the liner 5
Are shown. That is, the exhaust manifold 2 includes the ceramic liner 5 forming the exhaust passage 18, the heat insulating layer 6 disposed on the outer periphery except for the end 11 of the liner 5, and the liner 5 separated from the end face of the heat insulating layer 6. And a metal outer member 7 disposed on the outer periphery of the ring 3, the heat insulating layer 6 and the liner 5 by casting. Accordingly, a ring-shaped protrusion 9 extending inward in the radial direction is formed in a portion where the ring 3 and the heat insulating layer 6 are separated by casting a metal for forming the outer member 7.

In this exhaust manifold mounting structure,
The liner 5 is made of ceramics such as aluminum titanate having a very low thermal conductivity and a small specific gravity. In particular, the metal ring 3 is made of a metal having a higher melting point and a higher elastic modulus than the metal of the outer member 7. For example,
When the outer member 7 is made by casting with Al metal, the metal ring 3 is preferably made of Fc or ceramics such as alumina Al ₂ O ₃ , and the outer member 7 is made of Fc metal. When it is manufactured by casting, it is preferable that the metal ring 3 be made of ceramics such as alumina Al ₂ O ₃ . That is, the melting point of Al is 6
60 ° C. and the elastic modulus is 7000 kgf / mm ² , the melting point of Fc is 1500 ° C. and the elastic modulus is 150
00 kgf / mm ² , the melting point of Al ₂ O ₃ is 2050 ° C., and the elastic modulus is 35000 kgf / mm 2
²

In this exhaust manifold mounting structure,
The exhaust manifold 2 has a liner 5 made of ceramics having a low thermal conductivity and constituting an inner wall surface, and an outer member 7 made of a metal disposed outside the liner 5 via a heat insulating layer 5 by casting. In other words, the exhaust manifold mounting structure is such that the inner wall side annular groove 8 is formed in the flange portion 12 of the outer member 7, the metal ring 3 is disposed in the annular groove 8, and the gap between the end face 16 of the liner 5 and the gasket 4. Is set to. A ring-shaped protrusion 9 extending inward in the radial direction of the outer member 7 is in contact with a portion adjacent to the metal ring 3 on the outer peripheral surface 14 of the liner 5. The exhaust manifold 2 is fixed to the cylinder head 1 or a part of the exhaust pipe in a state where the end face 20 of the flange portion 12 and the end face 19 of the ring 3 constituting the mounting surface of the outer member 7 are in contact with the gasket 4. Exhaust manifold 2 to cylinder head 1
In a state where the liner 5 is fixed to such a component, the ring-shaped protrusion 9 contacts the outer peripheral surface 14 of the liner 5 to fix the radial direction of the liner 5 and the ring 3 fixes the axial direction of the liner 5. . Although not shown, the liner 5 can be composed of each branch portion communicating with each cylinder of the multi-cylinder engine, and a collecting portion which gathers each branch portion at a bent portion.

The exhaust manifold 2 is an assembly in which an exhaust manifold liner 5, a heat insulating layer 6, and a metal ring 3 are assembled, and the assembly is arranged in a casting mold to cast a metal such as an aluminum alloy or cast iron. This is one in which a metal outer member 7 is formed. The exhaust manifold 2 is attached to an opposing surface facing the exhaust manifold 2, that is, a side surface 13 of the cylinder head 1, and exhaust gas discharged from the multi-cylinder engine joins from a branch portion of the liner 5 of the exhaust manifold 2 to a collecting portion. Then, it is led to an exhaust pipe (not shown) connected to the collecting portion. The metal ring 3 is attached to the end face 16 of the exhaust manifold liner 5 in a state of abutting. The end face of the exhaust manifold 2 includes an end face 19 of the metal ring 3 and an end face 20 of the outer member 7.

Therefore, when the exhaust manifold 2 is fastened to the cylinder head 1 with the gasket 4 interposed therebetween by bolts or the like, a metal ring is provided between the opposing surface, that is, the end surface 13 of the cylinder head 1 and the end surface 19 of the liner 5. 3 are interposed. End face 13 of cylinder head 1 and end face 16 of liner 5
And a structure in which a metal ring 3 is interposed between
The influence of the heat load due to the heat shrinkage of the metal during the casting of the outer member 2 on the liner 5 is extremely reduced. That is, when the outer member 7 is formed by casting a metal in a state where the metal ring 3 is disposed on the end face 19 of the liner 5, the displacement of the metal ring 3 due to the thermal contraction of the metal is the displacement due to the thermal contraction of the outer member 7. The thermal expansion difference between the metal ring 3 and the liner 5 is reduced, and as a result, the thermal stress applied to the liner 5 can be reduced, and the fixing to the vibration generated in the outer member 7 is also strong. Become something.

[0023]

The exhaust manifold mounting structure according to the present invention is constructed as described above, and has the following effects. That is, the mounting structure of this exhaust manifold is as follows.
The exhaust manifold is made of ceramic liner with low thermal conductivity,
A heat insulating layer disposed on the outer periphery except for the end of the liner, a metal ring disposed on the outer periphery and the end surface of the liner spaced apart from the heat insulating layer, and the ring, the heat insulating layer, and the liner; In particular, the ring is made of a metal having a higher melting point and a higher elastic modulus than the metal of the outer member, so that the ring is formed at the end of the liner. By arranging the ring in contact, the thermal stress generated during the solidification and contraction of the metal of the outer member does not directly act on the end of the liner, but is received by the interposed ring.

That is, since the ring is made of a material having a sufficiently high melting point and a sufficiently high elastic modulus than the metal of the outer member, the ring generates thermal stress generated by thermal contraction of the outer member. The heat load due to the heat shrinkage of the ring itself is restrained and the liner can be prevented from being broken or cracked. Since the gasket and the ring are interposed between the end surface of the liner and the facing surface of the cylinder head or the exhaust pipe component, the combustion gas is prevented from leaking from the exhaust passage to the outer member, Heat flow to the seal and the outer member can be prevented, heat energy can be prevented from being dissipated to the outside, and energy recovery efficiency can be improved and durability can be improved.

In the exhaust manifold mounting structure, heat flow at the mounting end faces at both ends of the exhaust manifold is prevented, so that the exhaust manifold has a sufficient heat shielding property. Further, breakage of the liner is prevented, and the liner and the outer side are prevented from being damaged. Since a heat insulating layer is interposed between the components, if used in a heat shield engine, the exhaust gas energy from the heat shield engine is effectively maintained, and the exhaust gas energy is supplied to a turbocharger disposed downstream of the exhaust system. Energy can be effectively recovered by the charger or the energy recovery device, and fuel consumption can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of an exhaust manifold mounting structure according to the present invention.

FIG. 2 is a cross-sectional view showing one example of a conventional exhaust manifold mounting structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder head 2 Exhaust manifold 3 Metal ring 4 Gasket 5 Liner 6 Heat insulation layer 7 Outer member 8 Annular groove 9 Projection 11 Liner end 12 Flange 13 Cylinder head end surface 14 Outer peripheral surface 16 Liner end surface 17, 18 Exhaust passage 19,20 end face

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F01N 7/08 B22D 19/00 F01N 7/10 F01N 7/14

Claims (3)

(57) [Scope of request for utility model registration] 1. An exhaust manifold mounting structure in which an exhaust manifold is connected to a component forming an exhaust passage via a gasket, wherein the exhaust manifold has a low thermal conductivity ceramic liner forming an exhaust passage, and an end of the liner. Except for the heat insulating layer disposed on the outer periphery, the metal ring disposed on the outer periphery and the end surface of the liner at a distance from the heat insulating layer, and cast on the outer periphery of the ring, the heat insulating layer and the liner. Wherein the ring is made of a metal having a higher melting point and a higher elastic modulus than the metal of the outer member. 2. The exhaust manifold is fixed to the component in a state where end faces of a flange portion forming a mounting surface of the outer member and the ring are in contact with the gasket. Exhaust manifold mounting structure. 3. A radially inwardly extending ring-shaped projection of the outer member abutting an outer peripheral surface of the liner in which the ring and the heat insulating layer are spaced from each other, and fixes the radial direction of the liner. The exhaust manifold mounting structure according to claim 1, wherein an axial direction of the liner is fixed.