JPH07328453A - Self heating type honeycomb convertor - Google Patents

Abstract

PURPOSE:To obtain both of high resistance and low thermal capacity of a honeycomb carrier and to sufficiently raise temp. of the catalyst with a small electric power in a short time to activate a catalyst. CONSTITUTION:This honeycomb convertor is a self-heating type to be disposed in the route of exhaust gas from an engine. The honeycomb carrier 1 which carries the catalyst material consists of a flat plate and a wavy plate and has slits 2a, 3a as apertures in at least a part of these plates. A heat insulating supporting material 21 comprising a heat-resistant inorg. fiber material is inserted between the honeycomb carrier 1 to be energized and an outer cylinder which houses the honeycomb carrier 1. The honeycomb carrier and the heat insulating supporting material are arranged in such a manner that the position of the ends 21a, 21b of the material 21 as the start and finish points for rolling coincides with the position of the end of the flat plate or the wavy plate as the finish point of rolling, namely a projecting end 22 of the outermost layer of the honeycomb carrier 1. These points are deviated in the circumference direction. This prevents such a problem that the projecting end 22 is out of the space between the edges 21a, 21b and causes short circuit with the outer cylinder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalytic converter as an exhaust gas purifying device for automobiles, and more particularly to self-heating the catalyst carrier itself to generate heat in order to accelerate activation of a substance that performs a catalytic action. Type honeycomb converter.

[0002]

2. Description of the Related Art Conventionally, for example, a catalytic converter is interposed in an exhaust path of an automobile engine to convert harmful components such as CO, HC and NOx contained in exhaust gas into harmless gas or water. Has been done. However, when only the catalytic converter is used, there is a problem that the exhaust gas is hard to be purified because the catalytic substance is not activated when the temperature of the exhaust gas is low at the initial stage of engine startup.

Therefore, in US Pat. No. 3,770,389 and Japanese Patent Laid-Open No. 2-223622, the catalyst is supported in a separate self-heating type honeycomb filter with respect to the honeycomb carrier on which the catalyst is carried in the catalytic converter. There has been proposed a means for activating the catalyst substance by electrically heating this self-heating type honeycomb carrier by attaching a catalytic converter made of a self-heating type honeycomb carrier supporting the above.

In these self-heating type honeycomb carriers, corrugated metal plates in the form of strips formed by continuously bending corrugations and flat metal plates in the form of flat strips are alternately stacked. It is formed by winding or laminating.
When heating a catalytic converter using this self-heating type honeycomb carrier, electrodes are provided on the center and the outer surface of the honeycomb carrier, and a current is passed from the central portion toward the outer surface of the honeycomb carrier itself. To generate heat, thereby activating the catalyst substance supported on the honeycomb carrier.

[0005]

However, in such a self-heating type honeycomb carrier, a thin metal corrugated plate and a flat plate are formed on a metal thin corrugated plate in order to heat and raise the temperature by energizing the metallic honeycomb carrier itself. Therefore, in the case of a self-heating type honeycomb carrier in which a current flows from the center electrode to the outer surface, the band-shaped corrugated sheet material and the flat sheet material should be long enough to secure the resistance value. There is a need.

However, in such a conventional honeycomb carrier, since it is necessary to lengthen the metal foil as described above,
Since the heat capacity of the honeycomb carrier itself increases, the rate of temperature rise during energization becomes extremely slow, and there arises a problem that high purification performance cannot be obtained unless a large current is applied.

Further, in order to obtain a sufficient strength against vibration of the engine, it is desirable that the catalyst portions of the corrugated sheet material and the flat sheet material are mechanically joined, but while maintaining an electrically insulated state. Mechanical joining is very difficult. In particular, when a current is passed from the center electrode toward the outer surface, if the end surfaces are joined by welding, the resistance value cannot be obtained at all. Further, since it is not possible to easily weld the end faces of the honeycomb carrier because it is necessary to maintain electrical insulation, it becomes very difficult to give the honeycomb carrier sufficient strength.

Further, in the conventional catalytic converter, the heat generated in the metal foil forming the corrugated plate and the flat plate when the temperature is increased by energizing the honeycomb carrier is generated by heat conduction in the self-heating type honeycomb carrier. Since it spreads over the entire surface and escapes to the outside of the catalytic converter along the electrodes on the outer peripheral surface, it takes a very long time to even raise a part of the carrier to the activation temperature of the catalytic substance. was there. For the above reasons, it has been extremely difficult to satisfy both the securing of the resistance value and the reduction of the heat capacity in the honeycomb carrier.

In view of the above-mentioned problems in the prior art, the present invention achieves both high resistance and low heat capacity of the honeycomb carrier, low heat conduction and durability, and a slight amount within a short time. It is an object of the present invention to provide a self-heating type honeycomb converter that can raise the temperature to a sufficient temperature by electric power.

[0010]

To achieve this object, the present invention relates to a self-heating type honeycomb converter arranged in an exhaust path of an engine for purifying exhaust gas, the honeycomb carrying a catalytic substance. The carrier is composed of a flat plate and a corrugated plate, and the flat plate and / or the corrugated plate has a slit portion as an opening formed in at least a part thereof, and the honeycomb carrier and an outer cylinder containing the same A heat insulating holding material made of a heat-resistant inorganic fiber material is interposed between the inner peripheral surface of the heat insulating holding material and the starting point of winding of the heat insulating holding material when coating the honeycomb carrier with the heat insulating holding material. And the positions of the end edges which are the end points and the positions of the end edges which are the end points of the winding of the flat plate or the corrugated plate of the outermost layer of the honeycomb carrier do not coincide with each other, and these positions are shifted in the circumferential direction from each other. There is provided a self-heating type honeycomb converter, wherein the door.

[0011]

According to the present invention, by providing the flat plate or corrugated plate constituting the honeycomb carrier for the catalytic substance with the slit portion, it is possible to easily form the flat plate or corrugated plate having a higher electric resistance than the conventional one. Can be obtained. Therefore, unlike conventional products, long materials are not required for flat plates and corrugated plates.
The heat capacity of the honeycomb carrier can be made extremely small,
The temperature can be raised in a short time with low power. According to this structure,
Since it becomes possible to conduct electricity in the axial direction of the honeycomb, the center electrode having a large heat capacity can be omitted, and as a result, a further lower heat capacity can be realized.

Further, in the flat plate and the corrugated plate constituting the honeycomb carrier, the heat conduction in the axial direction is extremely small due to the slit portion, and the heat radiation to the outside is suppressed to a small extent by the heat insulating holding material covering the outer peripheral portion. The heat at the time of warming can be stored in the catalytic converter to increase the temperature rising rate.
Therefore, the input power can be small due to this heat storage effect.

The heat insulating retainer has a function of preventing blow-through of untreated gas in addition to ensuring the electrical insulation of the honeycomb carrier with respect to the outer cylinder. By offsetting the position and the winding end position of the foil material that constitutes the honeycomb in the circumferential direction, it is possible to prevent the honeycomb from short-circuiting with the outer cylinder, and by installing the stopper, damage to the heat insulating holding material It is possible to prevent blow-through, discharge of untreated gas, and high reliability can be realized.

[0014]

By implementing the present invention, it is possible to provide a self-heating type honeycomb converter which is excellent in durability and exhibits a function of purifying exhaust gas immediately after starting with low power.

[0015]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows a schematic diagram of a catalyst-supporting self-heating honeycomb carrier used in the self-heating honeycomb converter of the present invention. In the self-heating honeycomb carrier 1 of the example, a large number of slits are formed in the axial direction except the downstream end 1a which is a current inflow portion and the upstream end 1b which is a current outflow portion. The flat plate 2 and the corrugated plate 3 are overlapped and wound in a spiral shape.

In the self-heating type honeycomb carrier 1, the downstream end 1a is provided so that an electric current can be passed between the upstream end 1b and the downstream end 1a. A power supply means including a power supply 4 and a switch 5 is provided, and the upstream end 1b is grounded. Figure 2
[Fig. 4] is a front view showing in detail the shape of the first slit portion 2a formed on the flat plate 2 constituting the honeycomb carrier 1 in the example of the present invention.

The first slit portion 2a in this embodiment
The downstream-side end portion 1a of the upstream end portion 1b and the width l ₂ of width l ₁
It is formed in the middle part of the width l ₃ excluding and. And
A substantially rhombic opening 6 having a long diagonal line as a and a short diagonal line as b has a length of the diagonal line a of about 1 with respect to an adjacent opening 6.
It is formed by arranging a plurality of pieces in a positional relationship shifted from each other by / 2. The substantially rhombic slit portion can be manufactured by punching with a press or by making a cut in the longitudinal direction of the foil material and then expanding the foil material in a direction orthogonal to the cut. Needless to say, it can be manufactured by a method generally known as a method of processing such a mesh, in which the corrugated cutting tool is alternately moved by half pitch to cut and open the opening.

However, the shape of the opening is not limited to a substantially rhombic shape, but a rectangular opening 13 extending in the longitudinal direction of the foil material as shown in FIG. 3 or an oval shape with smooth corners of the slit. It is also possible to These slit shapes can be easily processed by punching with a press or by combining a roll having a cylindrical shape with a cutting tool arranged on the side surface and passing a foil material between them. In addition, if a relatively long slit portion is bent like the bent rectangular opening 13a shown in FIG. 4,
Since the current path length can be increased, it is particularly effective when a high resistance value is required.

The size and number of slits can be freely selected according to the required electric resistance and the heat capacity of the catalyst carrier. As shown in FIG. 5, the location of the slit portion is preferably on the upstream side of the honeycomb carrier where the temperature of the exhaust gas passing therethrough is high.

Concrete example of the honeycomb carrier 1 in this embodiment
Its physical size is 67 mm in diameter and 78 mm in length.
First slit portion 2a and second pick-up plate of plate 2 and corrugated plate 3
2a has substantially the same shape, and the size of the next part shown in FIG.
Each law is l₁= 10 mm, l ₂= 36.5 mm, l₃= 3
1.5 mm, l_Four= 0.15 mm, l_Five= 6 mm, l₆= 2 mm
I am trying. The material of the flat plate 2 is Cr 18
~ 24wt%, Al 4.5 ~ 5.5wt%, rare earth gold
The genus (REM) is 0.01 to 0.2 wt% and the balance is Fe
Fe-Cr-Al composition consisting of
It has a band shape of t = 0.03 to 0.05 mm.

The corrugated plate 3 also has a second slit portion 3 having the same shape as the first slit portion 2a formed on the flat plate 2.
a is formed, and unevenness is continuously formed.
In this embodiment, the height of the irregularities is 1.875 mm and the pitch in the longitudinal direction is 3.75 mm, but the height is 1.25 and the pitch is 2.5.
However, the invention is not limited by these exemplary dimensions.

Next, a method of manufacturing the self-heating honeycomb carrier of the embodiment will be described. The honeycomb carrier 1 in the self-heating type converter of the embodiment is divided so that the second slit portion 3a of the corrugated plate 3 faces the first slit portion 2a formed on the flat plate 2 as shown in FIG. It is sandwiched between the pin-shaped winding jigs 7a and 7b and overlapped. Then, the winding jigs 7a and 7b are wound to a predetermined size, and when the predetermined size is reached, the winding jigs 7a and 7b are removed.

After the honeycomb carrier 1 is wound to a predetermined size, the contact portions on both end faces of the flat plate 2 and the corrugated plate 3 are welded by electrical discharge welding, laser welding or brazing so as to be electrically short-circuited, The flat plate 2 and the corrugated plate 3 are joined.

More preferably, the winding jigs 7a, 7b
In the process of winding around, the flat plate 2 and the corrugated plate 3 may be spot-welded at a mutual contact point by a method such as laser welding or resistance welding. By using this method, the foil materials can be joined inside the honeycomb, so that the mechanical strength of the honeycomb can be increased, and large-scale equipment such as brazing is unnecessary. In addition, since the welding position and range can be controlled with high accuracy, there is an advantage that the heat resistant load structure can be realized relatively easily.

The bonded honeycomb carrier has γ-Al ₂ O.
A wash coat process is performed in which the slurry containing ₃ is dipped in the slurry to be impregnated and then baked. Before this step, the honeycomb carrier is heated at 800 ° C. to 1200 ° C. for 1 to 10 hours to perform an oxidation heat treatment for precipitating an oxide of Al on the metal surface, and adhesion of γ-Al ₂ O _{3 to} the foil material. May be increased. Then, it is impregnated in an aqueous solution containing a catalytic metal, such as Pt and Ph, and fired again. Alternatively, CeO ₂ may be supported as a cocatalyst. As a result, γ-
It is possible to obtain the self-heating type honeycomb carrier 1 in which Al ₂ O ₃ and the catalyst substance are attached.

Next, the casing of the self-heating type honeycomb carrier 1 will be described. With this casing, the self-heating type honeycomb carrier 1 of the embodiment is mounted in the exhaust path of the automobile. FIG. 7 shows a configuration diagram in which the self-heating type honeycomb carrier 1 thus manufactured is attached in the exhaust path.

As shown in FIG. 7, the honeycomb upstream end 1b is formed.
An upstream ring 8 and a downstream ring 9 made of stainless steel are joined to the downstream end portion 1a. These rings support the honeycomb and also function as current supply paths during energization. As a joining method, laser welding, brazing or the like can be applied. A flange 11 for attaching to the exhaust manifold 10 is joined to the upstream ring 8 by welding. Further, as shown in FIG. 8 showing a cross section AA of FIG. 7, a support member 12 made of stainless steel in consideration of heat resistance is attached to the downstream ring 9. Here, the pair of supporting members is two in total, but there is no problem even if the number of supporting members is three or more.

Further, the upstream ring 8 and the downstream ring 9 are
It is preferable to provide two or more stainless steel support members in the same manner as above, and to support the outer cylinder 20 via the two support members. In this case, heat dissipation due to conduction from the honeycomb is suppressed, and the heat storage effect is further enhanced. Therefore, it is desirable that the diameter of the support member 12 be as thin as possible within a range in which the current density during energization is excessively increased and abnormal resistance heat generation does not occur at the joint portion between the support member 12 and the rings 8 and 9.

The support member 12 is made of a ceramic gasket 14 in order to maintain electrical insulation from the outer case 20.
(14a and 14b) and gaskets 15a and 1
5b and a nut 16 which is screwed to the support rod 12 and fixed in an airtight state.

FIG. 9 shows a method of holding the honeycomb carrier 1 by the outer cylinder 20. As described with reference to FIG. 8, the upstream end ring 8 and the downstream end ring 9 serving as a base for fixing the honeycomb 1 are joined to the honeycomb ends 1b and 1a of the honeycomb carrier 1 where the slits are not formed. These rings 8 and 9 are made of stainless steel plate with a thickness of 1 mm or more, and are brazed, laser welded,
The whole or a part or a part of the honeycomb carrier 1 is bonded to both ends 1b and 1a of the honeycomb carrier 1 by a method such as spot welding. It is preferable that the series of steps such as the γ-alumina coating on the honeycomb carrier 1 and the supporting of the catalyst are performed after the rings 8 and 9 are bonded.

As described above, at least two rod-shaped support members 12 for connecting the honeycomb carrier 1 and the outer cylinder 20 to fix the honeycomb carrier are provided in the upstream and downstream rings 9 and 8, respectively. A total of 4 or more are joined. Outer cylinder 20
Has an inner diameter larger than the outer diameters of the honeycomb carrier 1 and the rings 8 and 9. Then, the support member 12 is vertically divided into two parts according to the number and the mounting position of the support members 12. Further, at the position where the support member 12 penetrates the outer cylinder 20, the support member 12
A concave portion 20a having a sufficient radius is formed so as not to contact the outer cylinder 20. With such a structure, assembly is extremely easy.

Although FIG. 9 shows an example in which a recess is provided on the joint end of the outer cylinder 20, as another example, a through hole may be provided in the side surface of the outer cylinder 20 to lead the electrode to the outside through the through hole. Also, take out only the electrode on the side not grounded,
A configuration in which the other is welded to the outer cylinder 20 and directly grounded is also possible. The number of divisions of the outer cylinder 20 is also 2 in the illustrated example.
However, the number may be two or more depending on the configuration of the electrodes.
As described above, when one of the support members is directly grounded by a method such as welding, at least one of the support members 12a on the side that is taken out to the outside and connected to the conductor as an electrode without being grounded is the other support. It is desirable to make the current density not too high by making the diameter thicker than the member and ensuring the cross-sectional area.

The support member 12a on the side which is not grounded but is taken out to the outside and connected to the conductor as an electrode needs to be electrically insulated from the portion other than the one honeycomb 1. At the same time, it must be hermetically sealed. In the example shown in FIG. 9, the support member 12a has a screw shape, a large outer diameter portion is provided at the root portion joined to the rings 8 and 9, and gaskets 14a and 14b made of a ceramic insulating heat-resistant material are provided. , Gaskets 15a, 15 each composed of at least one heat-resistant sealing material
Gasket 14a, cover 2
5, the gaskets 15b and 14b, and the nut 16 are attached to the support member 12a in this order.

When the nut 16 is fastened to this, the cover 25 is sandwiched between the nut 16 and the portion having a large outer diameter at the base of the support member 12a, and the cover 25 is covered with the gaskets 14a, 14b, 15a ,.
It is fixed while being pressurized by 15b. At this time, the outer diameter of at least one of the insulating gaskets 14a and 14b is changed in two steps, and the portion having the smaller outer diameter enters the hole of the cover 25 and is positioned. Next, the outer cylinder 20
After the outer cylinders 20 are covered with each other and welded to each other, the cover 25 is welded over the entire circumference around the recess (or hole) 20a of the outer cylinder 20. By doing so, the honeycomb carrier 1 is accurately positioned with respect to the outer cylinder 20, so that reliable insulation and vibration resistance can be obtained, and the honeycomb carrier 1 is prevented from being deformed or damaged due to strain generated during welding. It is possible to achieve high durability.

Further, a heat insulating material 21 having a heat insulating property, a sealing property and a cushioning property is provided between the outer cylinder 20 and the honeycomb carrier 1.
By filling and interposing, the vibration of the honeycomb carrier 1 due to the gas flow or the engine, the prevention of blow-through of untreated gas, the electrical insulation between the carrier and the outer cylinder, and the reduction of heat radiation from the honeycomb carrier 1 can be achieved. To be realized.

Here, as the heat insulating and holding material 21, a cloth-like material made of a short-fiber inorganic fiber material containing alumina and silica as main components, or a cloth-like material made of a heat-expandable inorganic fiber material containing vermiculite and the like. Any of the above can be used. The most preferable one is a structure in which the heat insulating holding material 21 is covered with a woven cloth made of a long fiber inorganic material containing silica as a main component, with a short fiber inorganic material containing alumina and silica as a main component.

10 and 11 show a method of assembling the heat insulating holding material 21. FIG. 10 is a perspective view, and FIG. 11 is a front view seen from the end face thereof. Since the honeycomb carrier 1 is constructed by winding a stainless steel foil provided with a mesh-shaped opening, the edge of the foil tip may open outward at the end of the outermost winding, which may project. . When the protruding end 22 comes into contact with the inner peripheral surface of the outer cylinder 20 through the gap of the heat insulating holding material 21, an electrical short circuit occurs, so that the honeycomb carrier 1 does not generate heat as designed, and a predetermined purification performance is obtained. I can't get it.

Therefore, in the example shown in FIG. 10, the position of the protruding end 22 of the honeycomb carrier 1 and the positions of the end edges 21a and 21b of the winding start and the winding end of the heat insulating holding material 21 are shifted so that the protruding end 22 is the end. It is configured so as not to go out of the heat insulating material 21 through a gap formed between the edges 21a and 21b. As a result, the risk of short circuit can be avoided, high reliability can be obtained, and workability in the assembling process can be improved. Further, when the heat insulating holding material 21 is formed in such a shape that the start point and the end point of the winding mesh with each other, the blow-through of gas can be reduced, so that the method shown in FIG. 10 is more effective in combination.

There is another method in which the length of the heat insulating holding material 21 in the longitudinal direction is made longer than the outer diameter of the honeycomb carrier 1 so that overlapping portions are always provided at the time of coating, but the heat insulating material is wasted, so that it is costly. Is a disadvantage.

By the way, the heat insulating holding material 21 may be reduced in volume or partially lost due to windage loss by being repeatedly exposed to the heat load and the exhaust gas flow. Since these phenomena cause a short circuit and blow-out of untreated gas, it is necessary to prevent blow-through of the heat insulating holding material by the following measures.

FIG. 12 shows the structure of the stopper 23 installed on the end surface of the heat insulating material 21 for preventing blow-by.
The annular stopper 23 is made of heat-resistant stainless steel plate,
In the illustrated embodiment, it is shown that it is attached to both the upstream side and the downstream side of the honeycomb carrier 1, but the stopper 23 is preferably installed at least on the downstream side of the honeycomb carrier 1. In this case, the stopper 23 is
Needless to say, the honeycomb carrier 1 is attached while maintaining its insulation.

The stopper 23 may be attached to the inner surface of the outer cylinder 20 as shown in the right end of FIG.
It may be attached according to the end surface of 0. When flanges 11a and 11b are provided at both ends of the converter as shown in FIG. 7, stoppers 2 are provided on these flanges.
You may attach 3. Further, although a configuration in which the honeycomb carrier 1 is attached to the rings 8 and 9 is possible, there is a drawback that the heat capacity of the honeycomb carrier 1 becomes large. However, in either configuration,
It is preferable that the space between the heat insulating holding material 21 and the axial end surface is extremely small or there is no space at all.

The stopper 23 can be integrally formed with any one of the three types of parts including the outer cylinder 20, the rings 8 and 9, and the flanges 11a and 11b. By doing so, it is possible to reduce the number of parts and the number of steps, and it is possible to provide a self-heating type catalytic converter excellent in cost. In this case as well, it is natural that the stopper 23 is attached while maintaining insulation between the outer cylinder 20 and the honeycomb 1.

As shown in FIG. 7, just downstream of the self-heating honeycomb carrier 1, a ceramic monolith catalyst 19 having a circular or oval cross section and a capacity of 800 to 1300 cc and supported by a wire net 18 in a case 17 is provided. Are arranged.

Next, the operation of the embodiment will be described. When 300 to 1000 W of electric power is supplied to the above-mentioned self-heating type honeycomb carrier 1 immediately after the engine is started, it is about 5 to 2
The self-heating honeycomb carrier 1 is rapidly heated to 400 ° C. to 500 ° C. in a time of about 0 sec (the engine is in an idling state), whereby the catalyst substance is activated and the gas discharged immediately after the engine is started can be purified. it can.

As described above, in the self-heating type honeycomb carrier 1 of the embodiment, since the flat plate 2 and the corrugated plate 3 are provided with the first and second slits 2a and 3a, the upstream end 1a and the downstream end 1a are formed. It is possible to easily construct a high-resistor that generates sufficient heat by passing an electric current between the parts and the metal foil. The carrier can be realized. Therefore, the temperature of the honeycomb carrier can be raised in a short time by low power, and the catalyst substance can be activated.

Further, since the positions of the first and second slits 2a and 3a formed on the flat plate 2 and the corrugated plate 3 are alternately shifted in the axial direction of the honeycomb carrier 1 by a half length, the conventional slits are formed. The heat conduction can be made extremely small as compared with a self-heating type honeycomb carrier having no heat.

Therefore, a portion reaching the activation temperature of the catalytic substance is generated early after the start of the temperature rise, and the heat of the catalytic reaction is received from this portion to raise the temperature of the other portion as well, so that the input power is increased. This also reduces the number.

Further, the first slit 2a and the second slit 3a formed on the flat plate 2 and the corrugated plate 3 made of a metal foil make the heat conduction in the axial direction extremely small, so
The heat at the time of temperature rise tends to be stored in the self-heating honeycomb carrier. As a result, after starting the temperature rise, there is a point where the activation temperature of the catalyst substance is reached earlier than in the case of the conventional self-heating type honeycomb carrier. Will be activated. In other words, the input power can be small due to this heat storage effect.

When the self-heating type catalytic converter is activated in this way, the temperature of the gas passing through the catalytic converter rises due to the heat of catalytic reaction. Therefore, the temperature of the ceramic monolith catalyst 19 installed on the downstream side should be increased. Therefore, the purification performance immediately after the engine is started can be improved.

In this embodiment, an example in which a ceramic monolith catalyst is installed on the downstream side has been described, but FIG. 13 shows a configuration in which the temperature raising performance is further emphasized. In this example, a plurality of small-capacity metal honeycomb converters 24a and 24b are combined with the self-heating catalyst converter described above. The metal honeycomb converter 24a having a much smaller heat capacity than the ceramic monolith catalyst is a self-heating catalyst. Upon receiving the heat of the converter, the temperature is rapidly raised to be activated, and the exhaust gas is purified, while further activating the metal honeycomb converter 24b on the downstream side.

Another effect of the slit is relaxation of thermal stress. In the case of the above-mentioned embodiment, the honeycomb carrier 1 is fixedly supported by the supporting member 12 on the upstream side and the downstream side. The honeycomb carrier 1 reaches a high temperature of 400 ° C. or higher within an extremely short time due to the exhaust gas temperature and the reaction heat of the catalytic reaction, but the outer cylinder 20 supporting the honeycomb carrier 1 is made of stainless steel having a thickness of 1 mm or more. Since it has a large heat capacity compared to 1, the temperature rise is slow, so
Axial thermal stress is generated between the honeycomb carrier 1 and the outer cylinder 20 due to the difference in thermal expansion between the two.

When the honeycomb carrier 1 is not provided with slits, stress acts in the direction of compressing the honeycomb carrier 1 in the high temperature state, resulting in damage called scoping. However, when the slits are provided as in the embodiment, the slit width is deformed with respect to the compressive stress, and the stress is relieved. Therefore, these slits have different shapes. Honeycomb 1
Has the effect of preventing damage. As a result, it is possible to provide a honeycomb carrier with a durability that is unprecedented.

Further, by performing the welding at the same time as winding the honeycomb carrier by using the laser welding method, the contact portion between the corrugated plate and the flat plate can be completely welded inside the honeycomb, so that the heat load and the engine vibration can be reduced. It is possible to realize a self-heating type honeycomb carrier having extremely strong and excellent durability.

In addition, the self-heating honeycomb carrier of the present invention shown in FIGS. 7 and 8 is mounted in close proximity to the exhaust manifold so that the temperature of the self-heating honeycomb carrier of the present invention can be raised early by receiving the heat of the exhaust gas. As shown, since such a place is also in a very severe environment where it is exposed to high temperature exhaust gas and engine vibration while the vehicle is running, even if it is installed under the floor of the vehicle, etc., like a general catalytic converter. Good.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a catalyst-supporting self-heating honeycomb carrier used in the self-heating honeycomb converter of the present invention.

FIG. 2 is a front view showing the shape of a first slit portion formed on a flat plate used in the first embodiment.

FIG. 3 is a front view showing a flat plate having a rectangular slit shape.

FIG. 4 is a front view showing a flat plate having a bent slit.

FIG. 5 is a front view showing a flat plate provided with a slit biased toward the upstream side.

FIG. 6 is a perspective view for explaining a method for manufacturing a honeycomb carrier.

[Fig. 7] Fig. 7 is a configuration diagram in which the self-heating honeycomb carrier of the example is attached in an exhaust path.

FIG. 8 is a side sectional view showing a section taken along line AA of FIG.

FIG. 9 is an exploded perspective view showing a holding structure of an outer cylinder of a honeycomb carrier.

FIG. 10 is a perspective view showing a method of assembling the heat insulating holding material.

FIG. 11 is a front view showing a method of assembling the heat insulating holding material.

FIG. 12 is a cross-sectional view showing a configuration in which a stopper is installed on an end surface of a heat insulating holding material.

FIG. 13 is a cross-sectional view showing an example of a self-heating type catalytic converter in which a plurality of metal honeycomb converters each having a small capacity are provided on the downstream side.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Honeycomb carrier 1a ... Downstream end 1b ... Upstream end 2 ... Flat plate 2a ... First slit part 3 ... Corrugated plate 3a ... Second slit part 6 ... Substantially rhombic opening 7a, 7b ... Winding jig 8 ... Upstream side ring 9 ... Downstream side ring 10 ... Exhaust manifold 11 ... Flange 12 ... Support member 13 ... Rectangular opening 13a ... Bent rectangular opening 14a, 14b ... Ceramic gasket 15a, 15b ... Gasket 16 ... Nut 19 ... Ceramic monolith catalyst 20 ... Outer cylinder 20a ... Recess 21 ... Insulation holding material 21a, 21b ... Edge 22 ... Projecting end (edge of flat plate or corrugated sheet) 23 ... Stopper 24a, 24b ... Metal honeycomb converter 25 ... Cover

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location F01N 3/20 ZAB K 3/28 ZAB 301 U 7/14 ZAB

Claims (12)

[Claims] 1. A self-heating type honeycomb converter arranged in an exhaust path of an engine for purifying exhaust gas, wherein a honeycomb carrier carrying a catalytic substance is composed of a flat plate and a corrugated plate. At least a part of the corrugated plate is formed with a slit as an opening, and a heat-resistant inorganic fiber material is formed between the honeycomb carrier and the inner peripheral surface of the outer cylinder accommodating the honeycomb carrier. A heat insulating holding material is interposed, and when covering the honeycomb carrier with the heat insulating holding material, the positions of the edge points that are the starting point and the end point of the winding of the heat insulating holding material, and the outermost layer of the honeycomb carrier. The self-heating honeycomb converter characterized in that the positions of the edges of the flat plate or the corrugated plate, which are the end points of the winding, do not coincide with each other, and these positions are displaced in the circumferential direction from each other. 2. The self-heating type honeycomb converter according to claim 1, further comprising a power supply means for supplying electricity between the upstream side and the downstream side of the flow of the exhaust gas of the honeycomb carrier. 3. The self-heating honeycomb converter according to claim 1, wherein the heat insulating and holding material is made of a short fiber inorganic fiber material containing alumina and / or silica as a main component. 4. A cloth or a woven fabric, wherein the heat insulating and retaining material is composed of a short fiber inorganic fiber material containing alumina and / or silica as a main component and a long fiber inorganic fiber material containing silica as a main component. The self-heating type honeycomb converter according to claim 1 or 2, which has a covered structure. 5. The self-heating honeycomb converter according to claim 1, wherein the heat insulating and holding material is made of a heat-expandable inorganic fiber material containing vermiculite. 6. The first edge and the last edge of the winding of the heat insulating and retaining material are configured to be meshed with each other in order to prevent gas blow-through. The self-heating honeycomb converter according to any one of 1. 7. The self-heating type honeycomb according to claim 1, wherein a stopper for preventing blow-through of the heat insulating holding material is provided on an end surface of the heat insulating holding material. converter. 8. The self-heating honeycomb converter according to claim 7, wherein the stopper is installed at least on the downstream side of the upstream side and the downstream side of the honeycomb carrier. 9. The self-heating honeycomb converter according to claim 7, wherein the stopper is provided only on the downstream side of the upstream side and the downstream side of the honeycomb carrier. 10. The self-heating honeycomb converter according to claim 7, wherein the stopper is installed only on the upstream side of the upstream side and the downstream side of the honeycomb carrier. 11. The stopper is attached to any one of a flange, an outer cylinder, a honeycomb carrier, and an electrode ring installed on the honeycomb carrier while being insulated from other portions. The self-heating honeycomb converter according to any one of claims 7 to 10. 12. The stopper is integrally formed with any one of a flange, an outer cylinder, a honeycomb carrier, and an electrode ring installed on the honeycomb carrier, and is attached while being insulated from other parts. Claims 7 to 1
0. A self-heating honeycomb converter according to any one of 0.