JP2577793Y2 - Exhaust manifold - 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 which 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]

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 turbochargers, but exhaust manifolds made of cast iron are very heavy and hinder engine weight reduction. In order to reduce the weight of the exhaust manifold, there has been disclosed a structure in which the liner on the inner surface of the aluminum alloy is made of ceramics having a low thermal conductivity in order to reduce the weight of the exhaust manifold and to form a heat shielding structure.

Conventionally, as a composite refractory for as-cast, there is one disclosed in Japanese Utility Model Laid-Open Publication No. 52-141023.
The composite refractory for stuffing is disposed on the inner wall surface of a casting for transporting a heating fluid therein, and refractory fibers and calcium silicate are formed on the entire outer peripheral surface of a ceramic refractory formed in a desired pipe shape in advance. A composite coating layer made of a hydrate is provided substantially uniformly, the refractory is placed in a mold, and a molten metal is poured into the mold to form the composite refractory into a cast-in piece. . 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 provided substantially uniformly on the refractory fiber layer.

[0004]

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.

[0005] Therefore, the engine is configured as a heat shielding structure,
In a case where the exhaust manifold in the exhaust system is configured to have a heat shielding structure so that the exhaust gas energy can be efficiently recovered by a turbocharger or an energy recovery device, a heat load is greatest at a collecting portion of the exhaust manifold, and The problem was to configure the part into a structure that could sufficiently withstand the heat load.

Accordingly, an object of the present invention is to solve the above-mentioned problems, and an exhaust manifold liner is made of ceramics such as aluminum titanate having a very low thermal conductivity and a small specific gravity. When casting a metal such as an aluminum alloy by placing it in a casting mold, the flow rate of exhaust gas increases and the ceramic fiber such as alumina fiber and nonwoven fabric is wrapped around the periphery of the exhaust manifold liner where heat load increases. An object of the present invention is to provide an exhaust manifold in which a molded heat-insulating member is disposed, a metal is cast, heat is blocked at a gathering portion, and the temperature of the metal disposed on an outer peripheral portion is reduced to improve durability. .

[0007]

The present invention is configured as follows to achieve the above object. That is, the present invention provides an exhaust manifold liner including a branch portion communicating with each cylinder of a multi-cylinder engine, and an assembly portion that gathers the branch portions into one through a bent portion, and a cast outside the exhaust manifold liner. An exhaust manifold comprising: a metal outer member disposed by means of a sleeve; wherein the exhaust manifold liner is made of ceramics having a low thermal conductivity, and wherein an area between the collecting portion of the exhaust manifold liner and the outer member is provided. Only a heat shield made of ceramic fiber with low thermal conductivity is interposed,
The present invention relates to an exhaust manifold, wherein the heat shielding member is not interposed in a region between the exhaust manifold liner and the outer member excluding the collecting portion.

In the exhaust manifold, the heat shielding member is made of alumina fiber, and the exhaust manifold liner is made of aluminum titanate.

[0009]

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

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an exhaust manifold according to the present invention. FIG. 1 is a plan view showing one embodiment of an exhaust manifold according to the present invention, and FIG.
FIG. 3 is a cross-sectional view taken along line XX of FIG. 1, and FIG. 3 is a plan view illustrating an exhaust manifold liner incorporated in the exhaust manifold.

FIGS. 1 and 2 show an exhaust manifold used in a multi-cylinder engine (four-cylinder engine is shown in the figures). FIG. 3 shows an exhaust manifold liner 1 in the exhaust manifold and a heat insulating member 7 of a molded body disposed outside the exhaust manifold liner 1.
The exhaust manifold liner 1 includes branch portions 2A, 2B, 2C, and 2D (hereinafter, generally referred to as a reference numeral 2) that communicate with each cylinder of the multi-cylinder engine, and a bent portion 3A that communicates with each branch portion 2. 3B, 3C, 3D (hereinafter, referred to as
The branch portion is generally denoted by reference numeral 3), and is composed of a straight portion 5 that collects the bent portions 3 and a collecting portion 4 that forms an outlet of the straight portion 5. The exhaust manifold liner 1 is made of ceramics such as aluminum titanate having a very low thermal conductivity and a small specific gravity.

With respect to this exhaust manifold, exhaust gas discharged from the multi-cylinder engine joins from the branch portion 2 of the exhaust manifold liner 1 to the collecting portion 4 and then to an exhaust pipe (not shown) connected to the collecting portion 4. As a result, the flow rate of the exhaust gas in the collecting part 4 is larger than that in the branch part 2, and the heat load of the collecting part 4 is increased. Therefore, if the outer member 8 made of metal is directly in contact with the collecting portion 4, the heat flow from the collecting portion 4 to the outer member 8 increases, and the temperature of the outer member 8 rises. Thus, the durability of the outer member 8 is deteriorated.

Therefore, the exhaust manifold according to the present invention has a heat shielding structure by disposing the exhaust manifold liner 1 in a casting mold and casting a metal such as aluminum (Al) alloy or cast iron (Fc). Before manufacturing the metal, a heat-shielding member 7 formed of a heat-insulating material in a molded body is disposed only on the outer peripheral surface of the collecting portion 4 of the exhaust manifold liner 1 before the metal casting step. The heat shielding member 7 is arranged in a casting mold and is cast with metal to form a metal outer member 8.

In this exhaust manifold, the heat shielding member 7
Is made of a ceramic fiber such as an alumina fiber (Al ₂ O ₃ fiber) or, in some cases, a non-woven fabric having a low thermal conductivity. 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, a split molded body 7A, 7B in a state where ceramic fibers are not fired. By contacting the compacts 7A, 7B to the outer peripheral surface of the exhaust manifold liner 1 and aligning the compacts 7A, 7B, the heat shield member 7 can be arranged on the outer peripheral surface of the exhaust manifold liner 1.

As described above, the exhaust manifold according to the present invention includes the exhaust manifold liner 1 and the metal outer member 8.
Since the heat shield member 7 is disposed between the first and second heat collectors 4 and the heat load is large, the heat flow from the inside to the outside of the heat collector 4 can be cut off. In this case, the temperature rise of the outer member 8 can be suppressed, and the temperature can be maintained at a low temperature, so that the heat influence of the outer member 8 can be reduced and the durability can be ensured. Further, the heat shield member 7 can alleviate the thermal influence on the exhaust manifold liner 1 and suppress the occurrence of cracks, breaks, and the like of the exhaust manifold liner 1.

Moreover, in this exhaust manifold, the heat shielding member 7 is a ceramic fiber, and since a large number of air layers are sealed in the internal structure, the heat shielding property of the exhaust manifold liner 1 made of aluminum titanate is reduced. There is no. 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 liner 1 is cast, the weight of the exhaust manifold can be reduced, which contributes 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 effectively recovered by the turbocharger, the recovery efficiency can be improved, and the fuel consumption can be reduced.

[0017]

The exhaust manifold according to the present invention has the following effects since it is configured as described above. That is, in this exhaust manifold, the exhaust manifold liner is made of ceramics having a low thermal conductivity, and a heat shielding member of a molded body made of ceramic fiber is interposed between the gathering portion of the exhaust manifold liner and the outer member made of metal. The aggregation part is 30 to
Although the temperature rises to about 50 ° C., the heat flow from the internal combustion gas passage to the outside is blocked by the heat shielding member to prevent heat dissipation in the collecting portion, and the temperature rise of the outer member in the collecting portion is suppressed. Low temperature can be maintained and durability can be ensured.

Further, in this exhaust manifold, the heat insulating member is made of alumina fiber, and since the internal structure is filled with a large number of air layers, the heat insulating member has a sufficient heat insulating property and is made of aluminum titanate. It does not adversely affect the heat insulation of the exhaust manifold liner. If this exhaust manifold is used in an engine, the energy of the exhaust gas from the heat shield engine can be effectively maintained, the energy can be effectively recovered by a turbocharger arranged downstream of the exhaust system, and the fuel consumption can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a sectional view taken along line XX of FIG. 1;

FIG. 3 is a plan view illustrating an exhaust manifold liner and a heat shield in the exhaust manifold of FIG. 1;

[Explanation of symbols]

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

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

Claims (2)

(57) [Scope of request for utility model registration] 1. An exhaust manifold liner comprising: a branch portion communicating with each cylinder of a multi-cylinder engine; and a collecting portion which gathers the branch portions into one through a bent portion, and a cast-in outside the exhaust manifold liner. The exhaust manifold liner is made of ceramics having a low thermal conductivity, and only an area between the gathering portion of the exhaust manifold liner and the outer member is provided. the heat shield is of intervention of ceramic fibers with low thermal conductivity
And the exhaust manifold liner and the
The heat shielding member is interposed in a region between the outer member and the outer member.
Exhaust manifold characterized by the absence . 2. The exhaust manifold according to claim 1, wherein said heat shielding member is made of alumina fiber, and said exhaust manifold liner is made of aluminum titanate.