JPS6118652B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an improvement of an exhaust manifold reactor suitable as an exhaust gas purification device for engines, particularly automobile engines.

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 a conventional exhaust manifold has been installed. 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. The exhaust gas inlet pipe from the engine that houses the heat insulating material and penetrates the same double shell structure, and the exhaust pipe that leads the exhaust gas re-burned in the core to the exhaust pipe pass through the exhaust pipe so that the exhaust gas flows into the double shell part. In order to prevent intrusion, burning out the insulation material and scattering it,
A seal ring is provided. 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, as shown in Japanese Utility Model Application Publication No. 49-138213, there is a manifold reactor in which a plurality of shielding tubes formed at intervals are installed inside a cylindrical outer case to form a re-combustion chamber. Although it has been proposed,
According to the manifold reactor, it is difficult to maintain the spacing between the shielding cylinders, and it is impossible to prevent heat transfer due to air convection between the shielding cylinders, resulting in poor insulation effect. It was hot.

The present invention was devised to solve the above-mentioned drawbacks of the conventional manifold reactor, and is made by winding corrugated plates and flat plates in multiple layers on the inner surface of a casing that receives and reburns engine exhaust gas. The gist of this invention is an exhaust manifold reactor characterized in that it is formed by interposing a heat insulating body having a heat insulating space formed by rotating the exhaust manifold.

According to the present invention, since a multi-layered corrugated plate and a flat plate are stacked to form a heat insulating body having a heat insulating space, it has excellent vibration resistance and thermal fatigue resistance, and has no moving parts, so noise is generated. There is no risk of this occurring, the structure is extremely simple, and the manufacturing cost can be reduced.

Further, according to the present invention, with the above configuration, the corrugated plate prevents heat transfer due to air convection in the heat insulating space, and has an excellent heat insulating effect.

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' and 2'' divided into two along a plane including the longitudinal center line 0-0, and the lower casing 2'' has the cylinder head 1. It has a flange 5 which is fixed by suitable tightening means such as bolts, 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, there is a hollow cylindrical heat insulator 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 insulator 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 welding 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 end edges 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', 2''. .

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
℃ to about 1000℃, but since most of the heat transfer in this case is radiation heat transfer, the insulation properties of the heat insulating body 11 having several layers of insulation spaces as described above are usually determined by the number of winding layers. It is practically sufficient to have 5 to 8 layers.

Next, FIG. 4 shows a second embodiment of the present invention, in which corrugated plates manufactured in the same manner as the heat insulating body 11 were installed inside the inlet pipe 3 and the discharge pipe 4 in the first embodiment. A multilayer body 11' is interposed as an aid to heat insulation. In addition, in the first and second embodiments described above, the discharge pipe 4 and the bolt 14 are provided approximately at the center in the longitudinal direction of the casing 2'', and the heat insulating body 11 is fixed to the casings 2' and 2'' at the center. Therefore, thermal expansion and contraction of the heat insulating body can be freely allowed.

5 and 6 show a third embodiment of the invention. In this case, the thin inner cylinder 8a of the heat insulating body 11 is manufactured to have a smaller diameter than in the first and second embodiments, and corrugated plates 9a and flat plates 10a are formed in multiple layers on the outer periphery by an amount corresponding to the difference in diameter between the thin inner cylinders. It is rolled. Then, at least one of several layers 18 of the corrugated plates 9a and 10a from the center is spray-coated, vapor-deposited, or plated with metal powder having a catalytic effect, and the outer layer 19
The corrugated plate and flat plate do not have a catalyst and have a longer longitudinal dimension than the catalyst support layer 18, and when the heat insulating body 11a is installed inside the casing, the shield plate 17 and the catalyst support layer 18 A gas diversion chamber 20 is formed between them. Furthermore, the hole on the heat insulating body 11a that accommodates the discharge pipe 4a does not penetrate through the thin inner cylinder 8a and reaches the first layer corrugated plate 4a, but the inner end of the discharge pipe 4a is connected to the catalyst support layer. It is fitted into the hole so as to be located at the boundary between the outer layer 18 and the outer layer 19. Therefore, the engine exhaust gas that has flowed into the inner cylinder 8a from the inlet pipe 3 enters the folding chamber 20 while being reburned within the inner cylinder 8a, and then flows between the catalyst support layers 18 due to the action of the catalyst. Harmless discharge pipe 4a
and flows into the exhaust pipe.

Further, FIG. 7 shows a fourth embodiment of the present invention, and FIG. 8 shows a fifth embodiment of the present invention.
An outer heat insulating layer 1 having a catalyst supporting layer 18 in the center of the 1c and having only a heat insulating effect without a catalyst on the outside thereof.
It has 9. In the embodiment shown in FIG. 7, the flow 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 3b is fitted is formed in the inner cylinder 8.
b, but reaches the first layer corrugated plate on its outer periphery, and the inner end of the introduction pipe 3b is connected to the catalyst support layer 18.
The discharge pipe 4b is fitted into the hole so as to be located at the boundary between the inner cylinder 8b and the outer layer 19, and the inner end of the discharge pipe 4b passes through the inner cylinder 8b. Therefore, the exhaust gas from the engine flows through the catalyst support layer 18 from the inlet pipe 3b,
During this time, harmful components in the gas are reburned and at least partially converted into harmless substances under the action of the catalyst, and then reburned in the inner cylinder 8b and discharged from the discharge pipe 4b to the discharge pipe. Furthermore, in the embodiment shown in FIG. 8, the inner cylinder 8b in the fourth embodiment is discontinued and a central shaft 21 is provided instead, and both ends of the central shaft 21 are supported on the casings 2', 2''.
The inner end of the exhaust pipe 4c is located at the boundary between the outer heat insulating layer 19 and the catalyst support layer 18, just as in the third embodiment. In this device, the introduction pipe 3c
While the exhaust gas introduced from the exhaust gas flows between the catalyst support layers 18, the harmful components thereof are re-burned and at the same time undergoes a conversion action by the catalyst, and most of them become harmless substances and are discharged from the exhaust pipe 4c.

FIG. 9 shows a sixth 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 11d 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 into the exhaust pipe. .

In the above third to sixth embodiments in which the heat insulating bodies 11a to 11d have a catalyst layer 18 and an outer heat insulating layer 19, the outer heat insulating layer 19 has a structure similar to that of the first and second embodiments. Moreover, it has sufficient heat insulation and heat retention effects, and exhibits the various effects mentioned above that are superior to conventional inorganic heat insulation materials.

Furthermore, FIG. 10 shows an embodiment in which a metal lath plate with corrugation is used as a modification of the corrugated plate 9, and this and a flat plate are wound together to produce a heat insulating body. In this modification, the contact heat transfer area is naturally reduced compared to the case where the flat plate is corrugated, 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. 11 shows an example of a structure for attaching the inlet pipes 3, 3b, 3c and the discharge pipes 4, 4a to 4c 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. 12A and 12B, 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 more preferable that the constituent plates in the heat insulating layer and the catalyst layer are not fixed together in order to maximize the flexibility of thermal deformation, but if necessary, for example,
It is also possible to perform high temperature brazing using a brazing agent such as Ni--Cr--B--Si alloy to achieve 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 the drawing]

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. Fig. 6 is a longitudinal sectional view similar to Fig. 1;
The figure is a cross-sectional view similar to FIG. 5 showing a fourth embodiment of the present invention, FIG. 8 is a cross-sectional view similar to FIG. 5 showing a fifth embodiment of the present invention, and FIG. 9 is a cross-sectional view similar to FIG. 10 is a perspective view showing still another modification of the above heat insulating body; FIG. 11 is a perspective view illustrating the procedure for machining the pipe hole of the above heat insulating body; 12.
Figures A and B are a plan view and a sectional view illustrating how to form a tube hole on the heat insulating body. 2...Manifold reactor, 2', 2''...Casing, 11, 11a, 11b, 11c, 11d...
Heat insulating heat insulating body, 18...catalyst supporting layer, 19... heat insulating layer.

Claims (1)

[Claims] 1. A heat insulating body with a heat insulating space formed by winding corrugated plates and flat plates in multiple layers is interposed on the inner surface of a casing that receives engine exhaust gas and recombusts it. exhaust manifold reactor.