JP2970348B2 - Automotive exhaust pipe and method of manufacturing the same - 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 pipe provided with a heat insulating cover in, for example, an exhaust manifold of an automobile engine and a method of manufacturing the same.

[0002]

2. Description of the Related Art As shown in FIG. 6, an exhaust manifold 9 for an automobile engine is an exhaust pipe 90 having a complicated shape which has a function of sending exhaust gas from an engine 8 to an exhaust pipe. The exhaust gas is sent from the exhaust pipe to the muffler.
And before the exhaust gas is exhausted from the muffler,
It is necessary to remove air pollutants with a catalytic converter. At this time, it is desirable that the exhaust gas temperature is high from the viewpoint of the efficiency of the catalytic reaction.

[0003] However, the temperature of the exhaust gas which has been high in the engine 8 is reduced before reaching the catalytic converter. Therefore, the exhaust pipe 90 needs to be thermally shielded. For this reason, conventionally, as shown in FIG. 7, a heat insulating cover 91 having a heat insulating layer 92 is widely provided in an exhaust pipe 90. In general, inorganic fibers are used for the heat insulating layer 92 from the viewpoint of heat resistance.

[0004]

However, the above-mentioned exhaust pipe 9
0 has an oxygen sensor mounting nozzle 3 as shown in FIG. In this part, the heat insulating cover 91 cannot be provided. That is, the shape of the nozzle 3 and its vicinity in the vicinity of the flange 32 are very complicated (see FIG. 6), and it is difficult to arrange the heat insulating cover 91 and the heat insulating layer 92 in close contact with each other. Therefore, in such a portion, the heat insulating layer 92 has an exposed end 920 (FIG. 7).

On the other hand, the engine 8 is a vibration source. Also, the body itself vibrates when the vehicle is running. For this reason, the exposed portion 920 of the heat insulating layer 92 made of the inorganic fiber is used.
As a result, as shown in FIG. 7, the inorganic fiber spills out due to this vibration, and a missing portion 921 is generated. As a result, there is a problem that the heat insulating layer 92 is lost in a part of the exhaust pipe 90 and the heat shield is insufficient.

Furthermore, the vicinity of the exhaust pipe 90 is in a high-temperature and dry environment. Therefore, the heat insulating layer 92 is made more brittle. The above state is a problem that occurs not only in the exhaust manifold but also in other exhaust pipes. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide an exhaust pipe for an automobile engine that has durability against vibration and high temperature and is easy to manufacture, and a method for manufacturing the same.

[0007] The present invention provides an exhaust pipe for guiding exhaust gas exhausted from an engine, a heat insulating cover covering the periphery of the exhaust pipe, and a heat insulating cover made of inorganic fibers disposed in a gap between the exhaust pipe and the heat insulating cover. In a car exhaust pipe consisting of layers,
The heat insulation layer is partially formed by the exhaust pipe and the heat insulation cover.
Has an exposed end exposed between
One exposed end of the heat insulating layer is in the vehicle exhaust pipe, characterized in that to form a cured portion impregnated with an inorganic binder.

What is most notable in the present invention is that the exposed end of the heat insulating layer has a hardened portion impregnated with an inorganic binder. The exposed end is a portion where the heat insulating layer is not covered by the heat insulating cover, which is usually located inside the end of the heat insulating cover, but may come out from the end of the heat insulating cover. . The heat insulating cover and the heat insulating layer are provided, for example, along the longitudinal direction of the exhaust pipe. Further, the heat-insulating cover and the heat-insulating layer may have openings at the sensor nozzle portion or the like in the exhaust pipe. The exposed end is also near this opening.
The hardened portion can be provided at a position other than the exposed end. The heat insulating cover uses a thin plate of, for example, stainless steel or aluminum.

The inorganic binder for forming the hardened portion is preferably an aqueous solution of a clay mineral such as silica sol, alumina sol and montmorillonite. The silica sol and the like are excellent in heat resistance and easily penetrate between fibers, and have an effect of high workability. The inorganic binder is impregnated in the heat insulating layer and dried to bind the inorganic fibers of the heat insulating layer to each other to form a hard layer.

The inorganic fibers are silica-alumina fibers,
It is preferable to use one or more of alumina fiber, silica fiber and glass fiber. These inorganic fibers are materials having high heat resistance and flexibility. Therefore, it is suitable as a heat insulating layer in an exhaust pipe where the temperature becomes high. Further, even when the shape of the exhaust pipe is complicated, it is easy to dispose the heat insulating layer.
The exhaust pipe is made of stainless steel, cast iron, or the like.

Further, as a method of manufacturing the exhaust pipe, an exhaust pipe for extracting exhaust gas discharged from an engine, a heat insulating cover covering the periphery of the exhaust pipe, and a gap between the exhaust pipe and the heat insulating cover are provided. Ri Do and a heat insulating layer consisting of set inorganic fibers, the heat insulation layer is the cross-sectional portion thereof and the exhaust pipe
With exposed end exposed between the thermal cover
Per in producing automotive exhaust pipe while creating, preformed with forming a heat insulating layer attaching portion of the insulating cover in the schematic shape along a shape of the exhaust pipe, formed by disposing the heat insulating layer in its interior A body is prepared, and then the exposed end of the heat insulating layer is impregnated with an inorganic binder,
These are dried to form a hardened part at the exposed end, and then
A method of manufacturing an exhaust pipe for an automobile, wherein the preform is coated on an exhaust pipe and fixed.

It is preferable that the heat insulating cover and the heat insulating layer are bonded in advance with an adhesive or the like. Thereby, both are firmly fixed. The adhesive used is heat-resistant. It is preferable that the heat-insulating cover in the preform be fixed to the exhaust pipe by caulking, bolting, and welding. From the viewpoint of workability, it is particularly preferable to fix by caulking. Thus, even when the exhaust pipe has a complicated shape, a heat insulating cover having a built-in heat insulating layer can be easily attached.

[0013]

[Operation and Effect] In the exhaust pipe of the present invention,
The heat insulation layer is partially formed by the exhaust pipe and the heat insulation cover.
Has an exposed end exposed between
The exposed end of the heat insulating layer has a cured portion impregnated with an inorganic binder. For this reason, the strength of the exposed end portion is improved, and even under adverse conditions such as vibration and high temperature, the inorganic fibers of the heat insulating layer do not spill out, and no missing portion is generated. Therefore, it has excellent durability against vibration and high temperature.

Further, the hardened portion is manufactured by impregnating an inorganic binder. Therefore, even for an exhaust pipe having a complicated shape, a hardened portion can be easily formed according to the shape of the exposed end of the heat insulating layer. Further, the heat insulating layer made of inorganic fibers is rich in flexibility. Therefore, it is suitable for manufacturing a heat insulating layer of an exhaust pipe having a complicated shape. Further, according to the above-described manufacturing method, it is possible to manufacture an exhaust pipe excellent in durability and easy to manufacture. As described above, according to the present invention, it is possible to provide an exhaust pipe for an automobile engine that has durability against vibration and high temperature and is easy to manufacture, and a method for manufacturing the same.

[0015]

【Example】

Embodiment 1 A vehicle exhaust pipe according to an embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. The automotive exhaust pipe of this example is used as an exhaust manifold. As shown in FIGS. 1 and 2, the exhaust manifold 1 of the present embodiment includes an exhaust pipe 10 for leading exhaust gas discharged from an engine, and a heat insulating cover 21 that covers the periphery of the exhaust pipe 10.
And a heat insulating layer 22 made of inorganic fibers disposed in a gap between the exhaust pipe 10 and the heat insulating cover 21. The exposed end 220 of the heat insulating layer 22 has a hardened portion impregnated with an inorganic binder. Note that, in FIG.
Is a mounting flange.

The exposed end 220 appears near the opening 210 of the heat insulating cover 21 and the heat insulating layer 22 in the vicinity of the oxygen sensor mounting nozzle 3 as shown in FIG. The oxygen sensor mounting nozzle 3 includes a sensor insertion hole 31, a sensor fixing flange 32, and a bolt hole 33. The sensor insertion hole 31 communicates with the exhaust pipe 10. Next, silica sol is used as the inorganic binder, and silica-alumina fiber is used as the inorganic fiber.

Next, a method of manufacturing the exhaust manifold 1 will be described with reference to FIG. That is, first, as shown in FIG.
Prepare 2 Next, as shown in FIG. 3B, the sheet 222 is bent to form the heat insulating layer 22. At the same time, the heat insulating cover 21 is formed into the general shape (arc shape) of the exhaust pipe 10. The heat insulating cover 21 is made of an aluminum plated steel plate or a stainless steel plate.

The heat insulating cover 21 and the heat insulating layer 22
Are bonded using a heat-resistant adhesive to produce a preform 4. An opening 210 is provided in the exhaust pipe 10 near the oxygen sensor mounting nozzle 3 (FIG. 3).
(D), FIG. 4).

Next, as shown in FIG. 3C, the exposed end 220 of the heat insulating layer 22 is impregnated with silica sol using the spray nozzle 5. Next, these are dried to form a hardened portion at the exposed end portion 220. Thereafter, as shown in FIG. 3D, the preform 4 is coated on the exhaust pipe 10 and fixed by caulking. In addition, the bolted portion 23
Is appropriately provided on the heat insulating cover 21 and fixed (FIG. 1). FIG. 3D is a sectional view taken along the line BB of FIG. FIG. 4 shows only the heat insulating layer 22. The heat insulating layer 22 is provided with an arc-shaped notch 225 at a portion located around the oxygen sensor mounting nozzle 3. The arc-shaped notch 225 forms an exposed end and has a hardened portion.

Next, the operation and effect of this embodiment will be described. In the exhaust manifold 1 of the present example, the exposed end 220 of the heat insulating layer 22 has a hardened portion. Therefore, at the exposed end portion 220, the heat insulating layer 22 does not have a missing portion. Therefore, it has excellent durability against vibration and high temperature.

The hardened portion is manufactured by impregnating a silica sol with a spray nozzle 5. Further, the heat insulating layer 22 made of silica-alumina fiber has high flexibility. Therefore, it is suitable for manufacturing the exhaust manifold 1 having a complicated shape. Further, silica sol and silica-alumina fiber have heat resistance. Therefore, the heat insulating layer does not deteriorate at high temperatures. As described above, according to this embodiment, it is possible to provide an exhaust pipe for an automobile engine which has durability against vibration and high temperature and is easy to manufacture, and a method for manufacturing the same.

Embodiment 2 In the exhaust manifold of this embodiment, the heat insulating layer 2
5 does not have the heat insulating cover 21 at its longitudinal end 221 as shown in FIG. The end 221 has a hardened portion sprayed with silica sol. The area of the hardened portion is larger than in the first embodiment. Others are the same as the first embodiment.

Also in this embodiment, the hardened portion of the heat insulating layer is manufactured by spraying silica sol with a spray nozzle as in the first embodiment. Accordingly, the exhaust manifold can be easily manufactured regardless of the size of the area of the hardened portion. In addition, the present embodiment can be applied as a means for providing a heat insulating layer in a place having a mounting flange such as a joint to an engine or an exhaust pipe in an exhaust manifold (FIG. 1). The other effects are the same as those of the first embodiment.

[Brief description of the drawings]

FIG. 1 is a plan view of the vicinity of an oxygen sensor mounting nozzle of an exhaust manifold according to a first embodiment.

FIG. 2 is a sectional view taken along the line AA in FIG.

FIG. 3 is an explanatory view of a manufacturing process of the exhaust manifold according to the first embodiment, and a cross-sectional view (D) taken along the line BB in FIG. 1;

FIG. 4 is a perspective view of a heat insulating layer of the exhaust manifold according to the first embodiment.

FIG. 5 is a perspective view of a heat insulating layer of an exhaust manifold according to a second embodiment.

FIG. 6 is a perspective view of a conventional exhaust manifold.

FIG. 7 is a cross-sectional view in the longitudinal direction of an exhaust pipe near an oxygen sensor mounting nozzle in a conventional exhaust manifold.

[Explanation of symbols]

 1,9. . . 9. Exhaust manifold, . . Exhaust pipe, 21. . . Heat insulation cover, 22. . . Heat insulation layer, 220. . . 3. exposed end; . . Preform, 8. . . engine,

Claims (6)

(57) [Claims] An exhaust pipe for guiding exhaust gas discharged from an engine, a heat insulating cover covering the exhaust pipe, and a heat insulating layer made of inorganic fibers disposed in a gap between the exhaust pipe and the heat insulating cover. A part of the heat-insulating layer comprises the exhaust pipe and the heat-insulating cover.
Has an exposed end exposed between
One exposed end of the heat insulating layer, vehicle exhaust pipe, characterized in that to form a cured portion impregnated with an inorganic binder. 2. The exhaust pipe according to claim 1, wherein the inorganic binder is an aqueous solution of a clay mineral such as silica sol, alumina sol, and montmorillonite. 3. The exhaust pipe according to claim 1, wherein the inorganic fiber is one or more of silica-alumina fiber, alumina fiber, silica fiber, and glass fiber. 4. An exhaust pipe for discharging exhaust gas discharged from an engine, a heat insulating cover covering a periphery of the exhaust pipe, and a heat insulating layer made of inorganic fibers disposed in a gap between the exhaust pipe and the heat insulating cover. Tona is, the heat insulating layer is a portion thereof above the exhaust
Exposed end exposed between the pipe and the heat insulating cover
Per in producing parts that have an exhaust pipe for a motor vehicle, with forming a heat insulating layer attaching portion the heat insulating cover in the schematic shape along a shape of the above exhaust pipe, the heat insulating layer arranged therein Then, the exposed end of the heat insulating layer is impregnated with an inorganic binder, and then dried to form a hardened portion at the exposed end. Then, the preformed body is evacuated. A method for manufacturing an exhaust pipe for a vehicle, comprising coating and fixing the pipe. 5. The method according to claim 5, wherein the inorganic binder is an aqueous solution of a clay mineral such as silica sol, alumina sol, and montmorillonite. 6. The method according to claim 5, wherein the inorganic fiber is at least one of silica-alumina fiber, alumina fiber, silica fiber, and glass fiber.