JPH02112864A - Manufacture of exhaust manifold for vehicle - Google Patents

Abstract

PURPOSE:To restrain increase of the weight and to improve the thermal insulation property by forming an inner pipe branching into plural pieces at one end part, covering the inner pipe thereof with inorganic fibrous heat insulating material and outside of the heat insulating material with outer shell and including both ends of the outer shell and the inner pipe as cast-in to form a flange. CONSTITUTION:The inner pipes of stainless steel plate-made first breeches pipe 12 and second breeches pipe 14 are shown with the broken line in the figure. The first breeches pipe is composed of cylindrical main pipe 16 and one pair of branching pipes 18, 20 branching to right and left two directions. On both breeches pipes 12, 14, the stringy heat insulating material 28 is wound without any gap. Further, both breeches pipes 12, 14 are provisionally fixed with wire 30 at three parts and the outside is integrally covered with the mild steel-made outer shell 32. The first flange 38 is fixed at the corresponding end parts of the main pipe 16, the main pipe 22 and the outer shell 32 with the cast-in. The second flange 40 and the third flange 42 are formed as the same way as the above, to connect each with an exhaust hole and exhaust pipe. By this method, the increase of weight of an exhaust manifold is restrained to low, and the thermal insulation property is improved and explosion sound of an engine and noise of exhaust gas are prevented from leakage to outside.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a vehicle exhaust manifold,
Especially regarding its weight reduction.

Conventional technology A vehicle exhaust manifold collects the exhaust gas emitted from multiple exhaust boats of an engine into one place and guides it to the exhaust pipe. It is necessary to have the desired shape. Although this exhaust manifold is generally integrally molded from cast iron, it is undeniable that it is heavy. Therefore, for example, as described in Japanese Patent Application Laid-Open No. 57-47523, a lightweight exhaust manifold is manufactured by manufacturing branch pipes from thin-walled pipe materials, combining these branch pipes, and attaching flanges to the ends by welding. was developed.

Problems to be Solved by the Invention However, the thin-walled exhaust manifold described above has a problem of insufficient heat insulation. In other words, it is desirable for the exhaust gas to be guided to the exhaust pipe in a high temperature state due to reasons such as the high appropriate temperature of the 0□ sensor, but thin-walled exhaust manifolds have poor insulation properties compared to cast iron exhaust manifolds. This caused the exhaust gas temperature to drop too much. Further, when the exhaust manifold is placed close to the intake pipe and the carburetor, the radiant heat of the exhaust manifold may have an adverse effect on the carburetor.

Further, the exhaust manifold must be able to prevent engine explosion sounds and the like from leaking to the outside, but conventional thin-walled exhaust manifolds have had the problem of insufficient sound insulation. In other words, noise leakage can be suppressed by suppressing the vibration of the exhaust manifold itself, but since conventional exhaust manifolds have smaller mass and rigidity than cast iron exhaust manifolds, it is difficult to suppress vibrations sufficiently. It could not be suppressed.

In view of these problems, the present invention has been made with the object of providing an exhaust manifold that is lightweight, has rich heat insulation properties, and has excellent sound insulation properties.

Means for Solving the Problems And the method for manufacturing an exhaust manifold according to the present invention includes:
(a) forming an inner tube with one end branched into multiple tubes, (1) covering the inner tube with an inorganic fiber insulation material, and (C) covering the outside of the insulation material with an outer shell. (d) covering the
The method includes a step of casting both ends of the outer shell and the inner tube to form a flange.

The materials for the inner tube and outer shell include mild steel, stainless steel,
A tube or plate material such as titanium (Ti) steel is preferable. In addition, carbon (C) fibers, silicon carbide (SiC) fibers, glass fibers, etc. are suitable as materials for the heat insulating material, and these inorganic fibers can be formed into a string or band shape and wrapped around the inner tube. Although desirable, the inner tube may be covered with a cloth-like material.

Effects and Effects According to the above manufacturing method, the inner tube is formed of a thin material, the inner tube is covered with a heat insulating material made of inorganic fibers, a layer of heat insulating material is formed around the outer periphery of the inner tube, and a layer of heat insulating material is formed on the outer periphery of the inner tube. By forming the outer shell, it is possible to improve the heat insulation and reduce the amount of heat radiated from the inner pipe to the outside due to the flow of exhaust gas. This makes it possible to improve heat insulation while suppressing an increase in the weight of the exhaust manifold.

In addition, since flanges are formed by casting at the ends of the inner tube and the ends of the outer shell, the sound insulation of the exhaust manifold is improved, reducing the explosion noise inside the engine and the flow of exhaust gas inside the exhaust manifold. It is possible to effectively prevent the noise associated with this from leaking to the outside. That is,
By integrally connecting the inner tube and the outer shell at each end, the rigidity of the exhaust manifold is increased and noise leakage is effectively reduced. Furthermore, since the heat insulating material also functions as a vibration damping material, vibrations of the inner tube are less likely to be transmitted to the outside, and noise leakage can be effectively reduced.

Furthermore, compared to when the flange is attached by welding, it is easier to increase the difference in thickness between the inner tube and the flange, so the flange can be provided with sufficient thickness, the inner tube can be thin, and the exhaust gas can be light. A manifold is obtained.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

In FIGS. 1 and 2, dashed lines indicate a first bifurcated tube 12 and a second bifurcated tube 1 made of stainless steel plates, which are inner tubes.
It is 4. As shown in FIG. 3, the first bifurcated pipe 12 consists of a circular main pipe 16 and a pair of branch pipes 18 and 20 that branch from one end of the main pipe 16 in two directions, left and right. . Further, the second bifurcated pipe 14 also consists of a main pipe 22 and branch pipes 24 and 26, as shown in FIG. A string-like heat insulating material 28 is wrapped around the first bifurcated tube 12 and the second bifurcated tube 14 without any gaps. In addition, both bifurcated tubes 1
2.14 has three locations, namely main pipe 16 and 22. Branch pipe 1
8 and 24 and one location each of the branch pipes 20 and 26 are temporarily fixed with a wire 30 (only one location is shown in FIG. 1), and the outside thereof is integrally covered with an outer shell 32 made of mild steel. ing.

The outer shell 32 consists of a pair of outer shell members 34,35,
A slight gap is formed between the outer shell 32 and the heat insulating material 32. Furthermore, the ends of the main pipe 16 of the first bifurcated pipe 12 and the main pipe 22 of the second bifurcated pipe 14 on the side opposite to the branch pipes and the corresponding ends of the outer shell 32 are made of molded metal. A first flange 38 is fixed by a wrapper. The first flange 38 is a plate-shaped member, and is used to connect the main pipes 16 and 22 to an exhaust pipe (not shown). Similarly, the ends of the branch pipe 18 of the first bifurcated pipe 12 and the branch pipe 24 of the second bifurcated pipe 14 and the outer shell 3
2 and the branch pipe 20 of the second bifurcated pipe 2
The end of the branch pipe 26 of the second bifurcated pipe 14 and the corresponding end of the outer shell 32 are also fitted with a second flange 40. by casting. A third flange 42 is formed. These second flanges 40 and third flanges 42 are connected to the branch pipes 18 and 2.
This is for connecting 024.26 to an engine exhaust port (not shown). Note that when the flanges 3 and 40 and 42 are formed, the space between the bifurcated tubes 12 and 14 and the outer shell 32 is sealed, but the ) is formed to allow air circulation as the air expands and contracts within the space.

Next, a method for manufacturing the exhaust manifold having the above structure will be described.

First, as shown in FIG. 5, the branch pipe 18 of the first bifurcated pipe 12
Manufacture. A stainless steel plate cut into a predetermined shape is cut into a straight pipe shape by normal bending, with one end 52 consisting of a flat plate part 54 and a semi-cylindrical part 56, and the other end 58 being cylindrical. The pipe is formed into a pipe, and the joint 60 is joined by welding. Alternatively, one end 52 of a tube having a circular cross-sectional shape may be formed into a semi-cylindrical shape. Then bent by ordinary pipe bender equipment,
In addition to the preforming process, the end portion 58 is flared to form a funnel-shaped tip.

Next, the semi-cylindrical end portions 52 of the branch pipe 18 and the branch pipe 20 manufactured in the same manner as the branch pipe 18 are brought into close contact with each other so that both form a circular shape, and the end of the flat plate portion 54 that is in close contact with each other is They are joined together by welding to integrate both branch pipes 18 and 20. On the other hand, one end is flared and the other end is an end 5.
2 is manufactured, and both branch pipes 18 and 20 are welded to the end face of the other end and joined, thereby manufacturing the first bifurcated pipe 12. .

The first bifurcated pipe 12 is further bulged to form a desirable exhaust gas flow path with low loss, and finally formed into the shape shown in FIG. 3.

Next, as shown in FIGS. 6 and 7, a string-like heat insulating material 28 is wrapped around the first bifurcated pipe 12. The heat insulating material 28 is made of silicon carbide (SiC), which is an inorganic fiber, and the main pipe 16. flanges 38, 40.4 at the ends of branch pipes 18, 20, respectively;
A heat insulating layer is formed by wrapping it around all parts except the part where 2 is formed without any gaps. In addition, before joining the branch pipes 18 and 20 to each other, the heat insulating material 28 may be wrapped around each of the branch pipes 18 and 20, and after joining, the insufficient wrapping may be supplemented. The second bifurcated tube 14 is also manufactured in the same process as the first bifurcated tube 12, and is wrapped with a heat insulating material 28.

Then, the first bifurcated tube 12 and the second bifurcated tube 14 are positioned using a jig (not shown), and the main tubes 16 and 22 are positioned using a wire 30. Branch pipes 1B and 24 and branch pipes 20 and 26 are temporarily fixed. Next, the first bifurcated pipe 12 and the second bifurcated pipe 14 are connected from above the heat insulating material 28 by a pair of outer shell members 34, 35 made of mild steel plates (thickness approximately 2 mm) that are separately press-formed. The outer shell 32 is formed by sandwiching the outer shell members 34 and 35 from two directions facing each other and welding the mating portions 36 of the pair of outer shell members 34 and 35. This joint part 3
Welding No. 6 may be butt welding or lap welding.

Further, the outer shell 32. The first bifurcated tube 12 and the second bifurcated tube 14 are set in a mold, and a first flange 38. The second flange 40 and the third flange 42 are formed by casting,
A mounting hole 62 is formed in each flange 38, 40.42.

At this time, since the ends of the bifurcated tube 12.14 and the outer shell 32 are both flared, separation of the flanges 38, 40.42 from them is effectively prevented.

In this embodiment, the first bifurcated tube 12 and the second bifurcated tube 14 are made of thin stainless steel plates, the heat insulating material 28 wound thereon is made of inorganic fiber, and the outer shell 32 is also relatively Since it is made of thin-walled mild steel plate, the exhaust manifold can be made lightweight.

In addition, the first bifurcated tube 12 and the second bifurcated tube 14 and the outer shell 32
Since a heat insulating layer made of the heat insulating material 28 is formed between the first and second bifurcated pipes 12 and 14, even if the first and second bifurcated pipes 12 and 14 are heated by the exhaust gas, the heat radiation from them is suppressed by the heat insulating material 28. , the amount of heat transferred to the outer shell 32 is reduced, and the heat insulation effect is enhanced.

Furthermore, the exhaust manifold of this embodiment can effectively prevent explosion sounds within the engine and noise associated with the flow of exhaust gas within the exhaust manifold from leaking to the outside. That is, if the exhaust manifold has a double structure and the ends of the bifurcated pipes 12, 14 and the outer shell 32 are integrally connected by flanges 38, 40, 42, the rigidity of the exhaust manifold can be increased.
This makes it possible to effectively reduce noise leakage.

Moreover, the almost sealed space interposed between the bifurcated tubes 12 and 14 and the outer shell 32 functions as a sound insulation layer, and
Since the heat insulating material 28 functions together with the vibration damping material, noise leakage can be effectively reduced.

Note that it is desirable that the outer shell 32 be thicker than the bifurcated tube 12.14, and if molding is difficult, an appropriate number of open lowers 0 may be formed as shown in FIGS. 8 and 9. may be formed. If an open lower 0 is formed, the above-mentioned heat insulation and sound insulation effects will be reduced, but even if the outer shell has an opening, it will function to increase the rigidity of the exhaust manifold and also function as a shielding member that blocks radiant heat. Therefore, it is effective in increasing heat insulation and soundproofing properties. Further, after the outer shell 32 is formed, the open lower part 0 can be closed by fixing the cover member by laser welding or the like.

Furthermore, in the embodiment, the outer shell 32 is the outer shell member 3.
4.35, the branch pipe 18 of the double-branched pipe 12.14 was formed by sandwiching the double-branched pipe 12.14,
A cylindrical outer shell member that covers the 24 side and a cylindrical outer shell member that covers the branch pipes 20 and 26 side are formed.
．． It is also possible to form the outer shell 32 by covering the outer shell 14 and welding both outer shell members at the center.

Further, in the above embodiment, the heat insulating material 28 is string-like, but it may be a band-like material, or a cloth-like material may be used to cover both the bifurcated tubes 12 and 14. outer shell 3
2, a heat insulating material such as a cloth is pasted on the inner surface of the outer shell member 34, 35 in advance, and both bifurcated pipes 12, 14 are covered at once with the outer shell 32 and the heat insulating material. It is also possible to do so.

Furthermore, the material of the insulation material is not limited to one type.
14 is first covered with a particularly heat-resistant heat insulating material such as silicon carbide or carbon, and then covered with a relatively inexpensive glass fiber heat insulating material, thereby reducing manufacturing costs.

Moreover, if the flanges 3B and 40.42 are made of titanium alloy casting, and the bifurcated pipes 12, 14 and the outer shell 32 are made of titanium, it is possible to further reduce the weight of the exhaust manifold.

In addition, the present invention can be practiced with various modifications and improvements based on the knowledge of those skilled in the art, such as changing the manufacturing method of the inner tube.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an exhaust manifold according to an embodiment of the present invention, and FIG. 2 is a side view thereof. FIGS. 3 and 4 are front views showing the first and second bifurcated tubes of the manifold, respectively. FIG. 5 is a perspective view showing one component of the double-branched pipe in the middle of processing, and FIGS. 6 and 7 show the branched pipes shown in FIGS. 3 and 4 wrapped with heat insulating material, respectively. It is a front view and a side view which show a state. 8 and 9 are views similar to FIGS. 1 and 2 showing an exhaust manifold according to another embodiment of the present invention. 12: First bifurcated pipe 28: Insulating material 38: First flange 42: Third flange 14: Second bifurcated pipe 32: Outer shell 40: Second flange

Claims (1)

[Claims] A step of forming an inner tube with one end branched into a plurality of tubes, a step of covering the inner tube with a heat insulating material made of inorganic fiber, a step of covering the outside of the insulating material with an outer shell, A method of manufacturing an exhaust manifold for a vehicle, comprising the step of casting both ends of the outer shell and the inner pipe to form a flange.