JPH0583320U - Exhaust manifold - Google Patents

Abstract

(57) [Summary] [PROBLEMS] The present invention provides an exhaust manifold that blocks heat flow in the collecting portion of the exhaust manifold and improves durability of an outer member of the collecting portion. [Structure] An exhaust manifold 1 in this exhaust manifold is connected to each branch portion 2 that communicates with each cylinder of a multi-cylinder engine, and each branch portion 2 is connected through a bending portion 3 to
It is composed of a gathering unit 4 that gathers together. The exhaust manifold 1 was made of low thermal conductivity ceramics and
An outer member 8 is formed by interposing a heat shield member 7 made of ceramic fiber made of alumina fiber on the outer peripheral surface of the metal and casting metal. The heat shield member 7 blocks the heat flow from the inside to the outside in the collecting portion 4, suppresses the temperature rise of the metal outer member 8 located on the outer peripheral surface of the collecting portion 4, and improves the durability.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an exhaust manifold that collects exhaust gas discharged from each cylinder of a multi-cylinder engine into a collecting portion and guides the exhaust gas to an exhaust pipe.

[0002]

[Prior Art]

 Currently, most exhaust manifolds used in engines are manufactured by casting cast iron in order to improve heat resistance and keep manufacturing costs low. Although cast iron has a high heat-resistant temperature, it also has a relatively good heat conduction, so it releases a large amount of heat from the combustion chamber. Many engines today are equipped with a turbocharger, but the exhaust manifold made of cast iron is very heavy and is a hindrance to engine weight reduction. Therefore, in order to reduce the weight of the exhaust manifold, it is disclosed that the liner on the inner surface of the aluminum alloy is made of a ceramic having a low thermal conductivity in order to make the exhaust manifold from the aluminum alloy and to construct a heat shield structure.

[0003] Conventionally, as a composite refractory material for cast iron, there is one disclosed in Japanese Utility Model Publication No. 52-141023. The cast refractory composite refractory is placed on the inner wall surface of the casting that transports the heating fluid inside, and the refractory fibers and silicic acid are formed on the entire outer peripheral surface of the ceramic refractory formed in a desired pipe shape in advance. A composite coating layer composed of calcium hydrate is provided substantially uniformly, this refractory is installed in a mold, and molten metal is poured into the mold to form a composite refractory integrally formed with the casting. is there. The composite coating layer is a coating layer in which a refractory fiber layer is first formed on the outer peripheral surface of a ceramic refractory, and a calcium silicate hydrate coating layer is substantially uniformly provided on the refractory fiber layer. is there.

[0004]

[Problems to be solved by the device]

 By the way, the exhaust gas discharged from each cylinder of the multi-cylinder engine joins the collecting portion through the branch portion and the bending portion of the exhaust manifold, and is discharged from the collecting portion to the exhaust pipe. Since the flow rate of is merged in the gathering portion, the flow rate becomes higher than that in the branch portion, and the flow velocity becomes faster, and the gathering portion becomes about 30 to 50 ° C. higher than in the branch portion. Also, in order to reduce the amount of heat released from the combustion chamber and to effectively apply the thermal energy of the exhaust gas to the turbocharger installed in the engine, an exhaust gas made of ceramics with extremely low thermal conductivity and low specific gravity is used. A manufacturing method in which the manifold liner is cast with a metal such as an aluminum alloy can be considered.

Therefore, when the engine has a heat shield structure and the exhaust manifold in the exhaust system has a heat shield structure so that the exhaust gas energy can be efficiently recovered by a turbocharger or an energy recovery device, The manifold assembly has the largest heat load, and it has been a challenge to construct the structure so that it can sufficiently withstand the heat load.

Therefore, an object of the present invention is to solve the above-mentioned problems, and an exhaust manifold is manufactured by using a ceramic such as aluminum titanate having a very low thermal conductivity and a small specific gravity, and the exhaust gas is exhausted. When placing a manifold liner in a casting mold and casting a metal such as an aluminum alloy, the flow rate of exhaust gas increases and the heat load increases. Alumina fiber, non-woven fabric, or other ceramic material is attached to the outer periphery of the exhaust manifold liner assembly. To provide an exhaust manifold with improved durability by lowering the temperature of the metal arranged on the outer periphery by shielding the heat flow at the gathering part by arranging a heat shielding member molded with a cop fiber to cast metal. Is.

[0007]

[Means for Solving the Problems]

 The present invention is configured as follows to achieve the above object. That is, the present invention provides an exhaust manifold liner including branch parts communicating with each cylinder of a multi-cylinder engine and a collecting part that collects the branch parts into one through bending parts, and an exhaust manifold liner outside the exhaust manifold liner. In an exhaust manifold consisting of an outer member made of metal and arranged by a cast metal, the exhaust manifold liner is made of ceramics with a low thermal conductivity, and a low heat resistance is provided between the gathering part of the exhaust manifold liner and the outer member. The present invention relates to an exhaust manifold including a heat shield member made of a ceramic fiber having conductivity.

Further, in the exhaust manifold, the heat shield member is made of alumina fiber, and the exhaust manifold liner is made of aluminum titanate.

[0009]

[Action]

 Since the exhaust manifold according to the present invention is constructed as described above, it operates as follows. In this exhaust manifold, the exhaust manifold is made of ceramics having a low thermal conductivity, and a heat shield member made of a ceramic fiber having a low thermal conductivity is interposed between the assembly portion of the exhaust manifold and the outer member. Therefore, the heat flow to the outside at the gathering portion can be shielded, the temperature of the metal of the outer peripheral member can be reduced, and the durability can be ensured.

[0010]

【Example】

 An embodiment of an exhaust manifold according to the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing an embodiment of an exhaust manifold according to the present invention, FIG. 2 is a sectional view taken along line XX in FIG. 1, and FIG. 3 is a plan view showing an exhaust manifold liner incorporated in the exhaust manifold. Is.

1 and 2 show an exhaust manifold used in a multi-cylinder engine (a four-cylinder engine is shown in the figures). FIG. 3 shows the exhaust manifold 1 in the exhaust manifold and the heat shield member 7 of the molded body arranged outside the exhaust manifold 1. The exhaust manifold 1 includes branch parts 2A, 2B, 2C, 2D (hereinafter, the branch parts are collectively referred to by reference numeral 2) that communicate with the cylinders of the multi-cylinder engine, and bent parts that communicate with the branch parts 2. 3A, 3B, 3C, 3D (hereinafter, referred to as a general term for a branch portion is denoted by reference numeral 3), a straight portion 5 that gathers the bent portion 3 and a gathering portion 4 that constitutes an outlet of the straight portion 5. The exhaust manifold 1 is made of ceramics such as aluminum titanate having a very low thermal conductivity and a small specific gravity.

Regarding this exhaust manifold, the exhaust gas discharged from the multi-cylinder engine merges from the branch portion 2 of the exhaust manifold 1 to the collecting portion 4, and then an exhaust pipe (not shown) connected to the collecting portion 4 However, the flow rate of the exhaust gas in the collecting portion 4 is larger than that in the branch portion 2, and the heat load of the collecting portion 4 is large. Therefore, if it is assumed that the outer member 8 made of metal is in direct contact with the collecting portion 4, the heat flow from the collecting portion 4 to the outer member 8 is large, and the temperature of the outer member 8 rises. However, the durability of the outer member 8 deteriorates.

Therefore, in the exhaust manifold according to the present invention, in particular, the exhaust manifold liner 1 is arranged in a casting mold and a metal such as an aluminum (Al) alloy or cast iron (Fc) is cast into the exhaust manifold so that the exhaust manifold has a heat shield structure. When manufacturing a manifold, prior to the metal casting step, the heat shield member 7 formed on the molded body with a heat shield material is arranged only on the outer peripheral surface of the collecting portion 4 of the exhaust manifold liner 1, and then the exhaust manifold liner. 1 and the heat shield member 7 are arranged in a casting mold and are cast around with metal to form a metal outer member 8.

In this exhaust manifold, the heat shield member 7 is made of a ceramic fiber such as an alumina fiber (Al ₂ O ₃ fiber) or, in some cases, a low thermal conductivity nonwoven fabric. In order to arrange the heat shield member 7 on the outer peripheral surface of the exhaust manifold liner 1, the heat shield member 7 is made of, for example, two molded bodies 7A and 7B in a molded state in which the ceramic fiber is not fired. The heat shield member 7 can be arranged on the outer peripheral surface of the exhaust manifold liner 1 by applying the molded body 7A, 7B to the outer peripheral surface of the exhaust manifold liner 1 and aligning the molded body 7A, 7B.

In the exhaust manifold according to the present invention, as described above, the heat shield member 7 is disposed between the exhaust manifold 1 and the metal outer member 8 and in the collecting portion 4 having a large heat load. The heat flow from the inside to the outside in the collecting portion 4 can be blocked, and particularly when the outer member 8 is made of an aluminum alloy, the temperature rise of the outer member 8 can be suppressed and the low temperature can be maintained. The heat effect of the member 8 can be reduced and durability can be ensured. Further, the heat shield member 7 can mitigate the heat influence on the exhaust manifold liner 1 and suppress the occurrence of damage such as cracks or breaks in the exhaust manifold liner 1.

Moreover, in this exhaust manifold, the heat shield member 7 is a ceramic fiber, and since many air layers are enclosed in the internal structure, the heat shield property of the exhaust manifold liner 1 made of aluminum titanate is lowered. Never. Also, by using a metal such as an aluminum alloy having a smaller specific gravity from cast iron as the metal into which the exhaust manifold 1 is cast, the weight of this exhaust manifold can be reduced, contributing to the weight reduction of the exhaust manifold. become. Furthermore, if this exhaust manifold is used in an engine, the exhaust gas energy from the engine can be maintained and can be effectively recovered by the turbocharger, the recovery efficiency can be improved, and fuel consumption can be reduced.

[0017]

[Effect of the device]

 Since the exhaust manifold according to the present invention is configured as described above, it has the following effects. In other words, the exhaust manifold is made of ceramics with low thermal conductivity, and a heat shield member made of a ceramic fiber is interposed between the exhaust manifold manifold and the outer member made of metal. Therefore, the gathering portion has a temperature of about 30 to 50 ° C. higher than that of the branch portion, but at the gathering portion, the heat flow from the internal combustion gas passage to the outside is shut off by the heat shield member to prevent radiation. However, it is possible to suppress the temperature rise of the outer member in the collecting portion and maintain it at a low temperature, and it is possible to ensure durability.

Further, in this exhaust manifold, the heat shield member is an alumina fiber, and since a large number of air layers are enclosed in the internal structure, it has sufficient heat shield property and is made of aluminum titanate. It does not adversely affect the heat shielding property of the exhaust manifold liner. If this exhaust manifold is used for the engine, the exhaust gas energy from the heat shield engine can be effectively maintained and the energy can be effectively recovered by the turbocharger placed in the downstream of the exhaust system, which can reduce fuel consumption. ..

[Brief description of drawings]

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

2 is a cross-sectional view taken along the line XX of FIG.

3 is a plan view illustrating an exhaust manifold liner and a heat shield member in the exhaust manifold of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exhaust manifold liner 2 Branch part 3 Bending part 4 Collecting part 5 Straight part 7 Heat shield member 7A, 7B Molded body 8 Outside member

Claims (2)

[Scope of utility model registration request] 1. An exhaust manifold liner comprising a branch part communicating with each cylinder of a multi-cylinder engine and a collecting part collecting the branch parts into one through a bending part, and a cast gurney on the outside of the exhaust manifold liner. In the exhaust manifold including the outer member made of metal, the exhaust manifold liner is made of ceramics having a low thermal conductivity, and the exhaust manifold has a low thermal conductivity between the collecting portion of the exhaust manifold liner and the outer member. Exhaust manifold, characterized in that there is an intervening heat shield member consisting of a ceramic fiber. 2. The exhaust manifold according to claim 1, wherein the heat shield member is made of alumina fiber, and the exhaust manifold liner is made of aluminum titanate.