JPS6339763B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in an exhaust manifold reactor suitable as an exhaust gas purification device for engines, particularly automobile engines.

[Problems with conventional technology]

In recent years, in order to convert harmful components such as HC, CO, and NOx in exhaust gas from automobile engines into harmless components and emit them into the atmosphere, a catalytic converter has been installed in the middle of the exhaust system, or in place of the conventional exhaust manifold. A manifold reactor, commonly called a thermal reactor, which removes harmful components in exhaust gas by thermal reaction, has been put into practical use.

As is well known, in the above-mentioned manifold reactor, it is necessary to maintain sufficient heat in order to actively re-burn the harmful unburned components in the exhaust gas and improve the purification efficiency. Metal insulation material was used. However, this type of non-metallic heat insulating material generally lacks mechanical strength and is easily corroded by contact with exhaust gas, so it is kept in a double shell structure consisting of a core and reactor casing that limit the exhaust gas re-combustion chamber. The exhaust gas enters into the double shell part through the exhaust gas inlet pipe from the engine that houses the material and penetrates the double shell structure, and the exhaust pipe that leads the exhaust gas reburned in the core to the exhaust pipe. A seal ring is provided to prevent the heat insulating material from burning out and being scattered. However, the seal ring is required to exhibit sufficient sealing performance while allowing free thermal expansion and contraction of the casing and core, as well as the exhaust gas inlet pipe and exhaust pipe. Sufficient consideration must be taken to avoid noise from colliding with surrounding parts such as the inlet pipe and discharge pipe, which not only makes the structure extremely complex and expensive, but also reduces the thermal fatigue resistance of the inorganic insulation material mentioned above. There are problems and there are concerns about the service life.

Furthermore, in Japanese Patent Application Laid-Open No. 49-20516, an inner cylinder main body formed in a spiral shape is disposed inside a closed cylindrical outer cylinder, and an exhaust gas inlet is communicated with the inside of the inner cylinder. A manifold reactor is described in which an outer open end formed between a main body and an outer cylinder is communicated with an outlet, but this manifold reactor cannot obtain a heat insulation effect due to the inner cylinder main body. Moreover, there was a problem that the exhaust gas purification efficiency was poor because the catalyst did not have a purifying effect.

[Means for solving problems]

The present invention was devised to solve the above-mentioned drawbacks of the conventional manifold reactor, and is made by winding multiple layers of metal plates on the inner surface of a casing that receives engine exhaust gas and recombusts it, with an appropriate heat insulating space. in which a part of the layer of the heat insulating body close to the inner surface of the casing is a non-breathable layer formed so that exhaust gas does not flow through the heat insulating space. The exhaust manifold reactor is characterized in that the exhaust manifold reactor is formed as a heat insulating layer, and the remaining layer is formed as a breathable catalyst support formed so that exhaust gas flows within the heat insulating space. .

〔Effect of the invention〕

According to the present invention, a heat insulating body formed by winding a plurality of layers of metal plates with an appropriate heat insulating space is interposed on the inner surface of the exhaust manifold reactor, so that it has excellent vibration resistance and thermal fatigue resistance, and Since there is no
There is no risk of noise generation, and the structure is extremely simple, which has the effect of reducing manufacturing costs.

In addition, a part of the layer close to the inner surface of the casing has a practically sufficient heat-insulating effect, and the exhaust gas is effectively re-combusted by the catalyst supported on the remaining layers.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, an embodiment in which the present invention is applied to a manifold reactor (hereinafter simply referred to as a reactor) of a four-cylinder engine will be specifically described with reference to the drawings.

First of all, FIGS. 1 to 3 show a first embodiment of the present invention, in which a reactor, generally designated by the reference numeral 2, is attached to the side of a cylinder head 1, and receives power from an engine (not shown). Exhaust gas is introduced into the reactor from the exhaust port of the cylinder head 1 through the introduction pipe 3, undergoes a combustion reaction within the reactor, flows into the exhaust pipe 4, and is discharged to an exhaust pipe (not shown). The reactor 2 has an overall cylindrical shape and includes upper and lower casings 2', 2'' divided into two along a plane including the longitudinal center line 0-0, and the lower casing 2'' has the above-mentioned cylinder head 1. It has a flange 5 which is fixed by an appropriate tightening means such as a bolt, a tubular part 6 into which the introduction pipe 3 is inserted, and a tubular part 7 into which the discharge pipe 4 is inserted. The inlet pipe 3 and the discharge pipe 4 are preferably made of a stainless steel material with high heat resistance and corrosion resistance, and the casings 2', 2'' may be made of inexpensive cast iron, or may be assembled by welding plate materials.

Inside the casings 2', 2'', as shown in FIG. 3, a hollow cylindrical heat insulator is formed by winding a corrugated plate 9 and a flat plate 10 wound together in multiple layers around the outer periphery of a thin inner cylinder 8. A heat insulating body 11 is installed inside.The winding start ends of the corrugated plate 9 and the flat plate 10 are fixed to the thin inner cylinder 8 by welding or brazing 12, and after being wound in a predetermined number of layers, the thin outer cylinder 13 is fixed. The heat insulating body 11 is manufactured by fitting the above-mentioned outer cylinder 13 onto the outer cylinder 13, and then holes are bored through which the inlet pipe 3 and the discharge pipe 4 pass, and stud bolts 14 are welded and fixed onto the outer cylinder 13. 14 into the corresponding bolt holes provided on the wall surface of the upper casing 2' and tightening the nuts 15, the heat insulating body 1
1 can be firmly supported within the casing. In place of the thin outer cylinder 13, the flat plate 10 may be wound in any number of layers after a predetermined number of layers have been wound together, and the terminal edge of the flat plate 10 may be fixed by welding or the like.

Both end openings of the heat insulating body 11 are closed by shielding plates 16, and a disc-shaped heat insulating material 17 made of ceramic fiber or the like is interposed between the shielding plate and the casings 2' and 2''. .

At least one of the several layers 18 of corrugated plates 9 and flat plates 10 from the center is spray-coated, vapor-deposited, or plated with metal powder that has a catalytic effect, and the corrugated plates and flat plates of the outer layer 19 are coated with a catalytic metal powder. When the insulating heat insulating body 11 is installed inside the casing without having a longitudinal dimension longer than the catalyst supporting layer 18, the shielding plate 1
7 and the catalyst support layer 18, a gas folding chamber 20 is provided between the
is beginning to form. Furthermore, the hole on the heat insulating body 11 that accommodates the discharge pipe 4 is formed into a thin inner cylinder 8.
The inner end of the discharge pipe 4 reaches the 9th part of the corrugated plate of the first layer without penetrating the catalyst support layer 1.
It is fitted into the hole so as to be located at the boundary between the outer layer 8 and the outer layer 19. Therefore, the engine exhaust gas that has flowed into the inner cylinder 8 from the introduction pipe 3 flows into the inner cylinder 8.
The fuel enters the folding chamber 20 while being re-burned inside, and then, while flowing between the catalyst support layers 18, is rendered harmless by the action of the catalyst and flows out from the exhaust pipe 4 to the exhaust pipe.

In the reactor 2 configured as described above, the heat insulating body 11 is made by winding multiple layers of thin metal corrugated plates 9 and flat plates 10, so it is different from conventional ceramic or glass fiber heat insulators. In comparison, it has excellent vibration resistance and thermal fatigue resistance, and since there are no moving parts, there is no risk of noise generation, and the structure is extremely simple, which has the advantage of reducing manufacturing costs.

Furthermore, the gas temperature inside reactor 2 is usually 300℃.
~1000℃, but since most of the heat transfer in this case is radiation heat transfer, the heat insulation properties of the heat insulating body 11 having several layers of heat insulating spaces as described above are usually equal to the number of winding layers. 5 to 8 layers is practically sufficient.

Further, FIG. 4 shows a second embodiment of the present invention, and FIG. 5 shows a third embodiment of the present invention.
A catalyst supporting layer 18 is provided in the center of b, and an outer heat insulating layer 19 having only a heat insulating effect and having no catalyst on the outside thereof.
It is equipped with In the embodiment shown in FIG. 4, the folding chambers 20 at both ends of the catalyst support layer 18 are formed in a truncated conical shape, and the hole into which the introduction pipe 3a is inserted is formed in the inner tube 8a.
The introduction pipe 3a does not penetrate through the hole, but reaches the corrugated plate of the first layer on its outer periphery, and is fitted into the hole so that the inner end of the introduction pipe 3a is located at the boundary between the catalyst support layer 18 and the outer layer 19, and The inner end of the discharge pipe 4a passes through the inner cylinder 8a. Therefore, the exhaust gas from the engine flows through the catalyst support layer 18 from the inlet pipe 3a, and during this time the harmful components in the gas are re-burned and at least partially converted into harmless substances by the action of the catalyst, and then It is re-burned in the cylinder 8a and is discharged from the discharge pipe 4a to the discharge pipe.

Furthermore, in the embodiment shown in FIG. 5, the inner cylinder 8a in the second embodiment is discontinued and a central shaft 21 is provided instead, both ends of the central shaft 21 are supported on the casings 2', 2'', and the discharge pipe 4b is located at the boundary between the outer heat insulating layer 19 and the catalyst supporting layer 18, just as in the first embodiment.In this device, the exhaust gas introduced from the inlet pipe 3b passes through the catalyst supporting layer While flowing between the layers 18, the harmful components are re-burned and at the same time undergo a conversion action by the catalyst, becoming mostly harmless substances and being discharged from the discharge pipe 4b.

Figure 6 shows a fourth embodiment of the present invention, which purifies harmful components in the engine exhaust gas by re-combustion and/or catalytic action while flowing vertically downward, and is often referred to as a combustor. However, in a broad sense, it is included in manifold reactors. In the figure, 22 is an exhaust gas collection lid that communicates with the exhaust port of the cylinder head 1, 23 is a body part,
24 is a lower lid connected to the exhaust pipe. Torso 23
A heat insulating body 11c similar to those in the third to fifth embodiments is housed inside, and the heat insulating body has a catalyst support layer 18 similar to the above in the center and an outer heat insulating layer 19 on the outer side thereof. . Further, partition plates 25 and 26 are interposed at the joint between the lower lid 24 of the collecting lid 22 and the body 23 in order to prevent exhaust gas from flowing into the outer heat insulating layer 19. Therefore, the exhaust gas from the engine first enters the collecting lid 22, is guided by the partition plate 25, and is reburned while flowing down the catalyst support layer 18, purified by the action of the catalyst, and discharged to the exhaust pipe. . Heat insulating body 11, 11a
In the first to fourth embodiments, in which the catalyst layer 11c has the catalyst layer 18 and the outer heat insulating layer 19, the outer heat insulating layer 1
No. 9 has a practically sufficient heat insulating effect and exhibits the various effects mentioned above that are superior to conventional inorganic heat insulating materials.

Furthermore, FIG. 7 shows a modification of the corrugated plate 9 in which a corrugated metal lath plate is used.
This figure shows an embodiment in which a heat insulating body is manufactured by winding this together with a flat plate. In this modification, the contact heat transfer area is naturally reduced compared to the case where a flat plate is made by corrugating, so the heat insulation properties are even better, and when the catalyst support layer 18 is provided, the contact area between the exhaust gas and the catalyst is reduced. There are merits such as increasing the size and reducing weight.

Next, FIG. 8 shows an example of a structure for attaching the inlet pipes 3, 3a, 3b and the discharge pipes 4, 4a, 4b to the heat insulating body constructed as described above. That is, holes for the introduction pipe and discharge pipe are drilled in the heat insulating body formed as described above (in this case, deformation during processing can be avoided by filling the space with water and freezing it), and It is preferable that a cylindrical spacer 30 having a flange 29 prepared in advance is fitted into the hole and fixed to the heat insulating body by welding 31, and that the introduction pipe and the discharge pipe are housed inside the spacer 30. In addition, as shown in FIGS. 9A and 9B, holes with a diameter d smaller than the outside diameter D of the inlet pipe and the outlet pipe are punched in advance at predetermined positions on each plate constituting the heat insulating body by press working. After winding each plate, the edge of the hole having the diameter d may be bent to obtain the desired diameter D.

Finally, the material of each plate constituting the heat insulating body is preferably stainless steel or nickel alloy, and the appropriate thickness of each plate is about 0.05 to 0.3 mm. Metal materials, thickness, shape, etc. other than those mentioned above may be appropriately selected depending on various design factors such as the catalytic effect, rigidity, and durability of the material itself. In addition, the composition of the catalyst metal or alloy coated on the plate material with the catalyst support layer 18 includes elements that act effectively in exhaust gas purification as metal oxides when the temperature is increased.
For example, in addition to common elements such as Ni, Cr, Co, Cu, and Mn, noble metal rare elements such as Pt, Ru, and Rh can also be widely used.

In the reactor of the present invention, it is preferable that the constituent plates in the heat insulating layer and the catalyst layer not be bonded to each other in order to increase the flexibility of thermal deformation as much as possible. -B
- High-temperature brazing may be performed using a brazing agent such as a Si alloy for fixation.

Also, between the outer periphery of the heat insulation layer and the reactor outer shell,
By interposing a nonmetallic material such as a thin layer of ceramic fiber, it can be used to assist in heat insulation and noise prevention.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing a first embodiment of the manifold reactor of the present invention, FIG. 2 is a cross-sectional view taken along the - line in FIG. 1, and FIG. 2 is a perspective view showing the manufacturing mode of the heat insulating body 11 in FIG. 2, FIG. 4 is a cross-sectional view similar to FIG. 2 showing the second embodiment of the present invention, and FIG. 5 is a third embodiment of the present invention. 2 is a cross-sectional view similar to that shown in FIG. 2, FIG. 6 is a longitudinal sectional view showing a fourth embodiment of the present invention, FIG. 7 is a perspective view showing yet another modification of the above-mentioned heat insulating body, and FIG. FIGS. 9A and 9B are a perspective view illustrating a procedure for forming a tube hole in the heat insulating heat insulator, and a plan view and a cross-sectional view illustrating a procedure for forming a tube hole on the heat insulator. 2... Manifold reactor, 2', 2''... Casing, 11, 11a, 11b, 11c... Heat insulating body, 18... Catalyst support layer, 19... Heat insulating layer.

Claims (1)

[Claims] 1 A heat insulating body formed by winding multiple layers of metal plates and having an appropriate heat insulating space is interposed on the inner surface of a casing that receives and re-combusts exhaust gas from the engine, where the heat insulating body is A part of the layer close to the inner surface of the casing is formed as a non-breathable heat insulating layer so that exhaust gas does not flow through the heat insulating space, and the remaining layer is formed so that exhaust gas flows through the heat insulating space. An exhaust manifold reactor characterized in that the reactor is formed as an air-permeable catalyst carrier.