JPH078802A - Catalyst carrier for energization type catalytic converter - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to a catalyst carrier of an electric heating type catalytic converter that heats only a specific part, and exhaust gas that is not purified and is exhausted until the entire catalyst carrier reaches an activation temperature. The purpose is to reduce the amount. A catalyst carrier that comprises a metal foil 3 carrying a catalyst laminated between both electrodes and devises short circuit and insulation in the thickness direction of the metal foil 3 to generate heat only in a specific portion 33. On the exhaust upstream side end surface, the portion where the specific portion 33 is located is concave, and an inclined surface or a curved surface is formed on at least a part of the boundary with other portions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst for an electric heating type catalytic converter which activates the catalyst before warming up the internal combustion engine by energizing itself to generate heat and enables purification of exhaust gas at that time. Regarding the carrier.

[0002]

2. Description of the Related Art A catalyst carrier of a general electric heating type catalytic converter has a plurality of metal foils carrying a catalyst arranged spirally from a center electrode to an outer cylinder which serves as the other electrode. Since this metal foil is covered with insulation, each metal foil can generate heat by applying a voltage to both electrodes.

[0003] This catalyst carrier requires all the metal foils to generate heat by energization, and therefore requires a considerably large amount of electric power in order to raise the temperature to the catalyst activation temperature in a short time, resulting in an increase in the size of the battery. In order to solve this problem, Japanese Patent Application No. 4-338
No. 556 describes an electric heating type catalytic converter that heats only a specific portion of a catalyst carrier by devising a short circuit and insulation in the radial direction of a metal foil.

In such a catalytic converter, power consumption can be considerably reduced by activating the catalyst by heating only a specific portion, and exhaust gas before engine warm-up is purified by this specific portion, The heat of the chemical reaction can raise the temperature of the entire catalyst carrier to the catalyst activation temperature in a relatively short time.

[0005]

In the above-mentioned prior art, the specific portion for generating heat is located at a position where exhaust gas can easily pass through. However, other portions pass through until other catalyst carriers reach the activation temperature. Exhaust gas is discharged into the atmosphere without being purified.

Therefore, an object of the present invention is to provide a catalyst carrier of an electric heating type catalytic converter which heats only a specific portion, until the entire catalyst carrier reaches an activation temperature without increasing the area of the specific portion. The purpose is to reduce the amount of exhaust gas emitted without purification.

[0007]

A catalyst carrier of an electric heating type catalytic converter according to the present invention comprises a metal foil carrying a catalyst laminated between both electrodes, and a short circuit in the thickness direction of the metal foil and In a catalyst carrier that devises insulation to generate heat only in a specific part, the exhaust upstream end surface of the catalyst carrier is
It is characterized in that the portion where the specific portion is located is concave, and an inclined surface or a curved surface is formed at least at a part of the boundary with other portions.

[0008]

In the catalyst carrier of the above-mentioned energization heat generation type catalytic converter, only a specific portion generates heat when a voltage is applied to both electrodes, and the exhaust upstream side end face has a concave portion where the specific portion is located. Since the inclined surface or the curved surface is formed on at least a part of the boundary with other portions, the exhaust gas is easily concentrated on the specific portion by the inclined surface or the curved surface.

[0009]

FIG. 1 is a front view showing a first embodiment of a catalyst carrier of an electric heating type catalytic converter according to the present invention. Figure 2
1 is a sectional view taken along the line AA of FIG. 1, and the left side is the exhaust upstream. In these figures, 1 is a center electrode, and 2 is an outer cylinder which serves as the other electrode. Reference numeral 3 denotes a metal foil which is composed of a corrugated plate and a flat plate and carries a catalyst, and one set or a plurality of sets is spirally laminated from the center electrode 1 to the outer cylinder 2. The metal foil 3 is insulation-coated with an oxide film or the like, and constitutes a first annular portion 31 near the center electrode 1, a second annular portion 32 near the outer cylinder 2, and a third annular portion 33 indicated by a dot therebetween.

As shown by the alternate long and short dash line in FIG. 2, when the metal foil 3 is spirally laminated, the third annular portion has a concave shape on the exhaust upstream side end surface and the central electrode 1 on the downstream side end surface. Is formed so as to project from the end surface of the. Next, the exhaust upstream side end face and the downstream side end face of the first and second annular portions 31, 32 are short-circuited in the radial direction by discharge joining. The downstream end face is finished perpendicular to the axis of the catalyst carrier by discharge joining as in the conventional case, but the exhaust upstream end face is made to melt the metal foil 3 at this time, and the third end of the third annular portion is formed over the entire circumference. It is finished to be an inclined surface toward the end face.

In the catalyst carrier thus constructed, when a voltage is applied to the center electrode 1 and the outer cylinder 2 serving as the other electrode when the engine is cold-started, the current is spirally laminated in the third annular portion 33. Since the electric resistance is higher than that of the first and second annular portions 31 and 32 in which the current flows along the metal foil 3 and the electric current flows in the radial direction, only the third annular portion generates heat and the catalyst activation temperature is increased. Reach Exhaust gas is this part 33
The other part of the catalyst carrier is heated by the heat of the chemical reaction and the entire catalyst carrier reaches the activation temperature in a relatively short time, and the exhaust gas after that can be satisfactorily purified.

In this embodiment, the third annular portion 33 of the catalyst carrier is used.
Since only the heat is generated, the power consumption is considerably smaller than that of the catalyst carrier that heats all, and the battery can be downsized. Further, the exhaust gas passing through the first and second annular portions 31 and 32 is discharged without being purified in a relatively short time before the entire catalyst carrier reaches the activation temperature. Since the inclined surface is directed toward the third annular portion 33 that serves as the heat generating portion, the exhaust gas easily flows into the third annular portion 33, and the amount of unpurified exhaust gas can be reduced. Of course, these inclined surfaces do not have to cross the inner and outer peripheries of the first and second annular portions 31 and 32 as shown in the drawing, but a chamfered shape on the side of the third annular portion 33 can achieve some effect. it can.

FIG. 3 is a front view showing a second embodiment of the catalyst carrier of the electric heating type catalytic converter according to the present invention. FIG. 4 is a cross-sectional view taken along the line BB of FIG. 3, and the left side is the exhaust upstream, as in FIG. Only the differences from the first embodiment described above will be described below. In the third annular portion 33 in this embodiment, only four substantially rectangular specific portions 33a in the exhaust upstream side end cross section shown by dots in FIGS. 3 and 4 are short-circuited in the radial direction by discharge joining.

In the catalyst carrier thus constructed, when a voltage is applied to the center electrode 1 and the outer cylinder 2 serving as the other electrode when the engine is cold-started, only the specific portions 33a of the third annular portion 33 are generated. First because it is shorted radially
Unlike the embodiment, the electric current flows through each specific portion 33a in the radial direction, and the specific portion 33a includes the first and second annular portions 31,
Since the electrical resistance is higher than 32, each specific portion 33
Only a heats up.

Since the exhaust upstream end faces of the first and second annular portions 31 and 32 are inclined as in the first embodiment, the exhaust gas can easily flow into the specific portion 33a,
Before the entire catalyst carrier reaches the activation temperature, the amount of exhaust gas that is unpurified and exhausted can be reduced. Further, in the first embodiment, particularly, most of the heat generated in the exhaust gas downstream side portion of the third annular portion 33 is only discharged to the downstream side exhaust passage, so that the power consumption is sufficiently utilized. However, by making the portion to generate heat as the specific portion on the exhaust upstream side of the third annular portion 33 as in the present embodiment, the exhaust gas purification performance can be maintained and the power consumption can be further reduced.

FIG. 5 is a front view showing a third embodiment of the catalyst carrier of the electric heating type catalytic converter according to the present invention. FIG. 6 is a cross-sectional view taken along the line CC of FIG. 5, and the left side is the upstream side of the exhaust gas as in FIG. Only the differences from the second embodiment described above will be described below. The specific portion 33a 'intended to generate heat in the present embodiment is provided inside the catalyst carrier downstream of the exhaust upstream side end cross section of the third annular portion 33.
This is because the exhaust gas upstream side end portion of the catalyst carrier is likely to be deteriorated due to adherence of harmful substances etc. of the exhaust gas, and thus the exhaust gas purification performance is slightly deteriorated as compared with the second embodiment, but the catalyst carrier should be used for a long period of time. This is because it is advantageous in making it possible. The radial short circuit of this portion is performed during the lamination of the metal foil 3.

In the thus constituted catalyst carrier, the exhaust gas upstream side end faces of the first and second annular portions 31 and 32 are inclined faces as in the second embodiment, so that the exhaust gas is heated. It becomes easy to flow into the specific portion 33a 'which becomes a part, and the same effect can be obtained.

In the second and third embodiments, the exhaust upstream side end surfaces of the first and second annular portions 31 and 32 do not have to be inclined surfaces over the entire circumference as in the first embodiment, but both specific portions. Three
Only the positions of 3a and 33a 'may be inclined surfaces. In addition, in the third annular portion 33, both specific portions 33
By exhausting a portion where a and 33a 'are not located and forming an inclined surface toward the adjacent specific portions 33a and 33a', the exhaust gas can more easily pass through the specific portions 33a and 33a 'and is discharged without being purified. The amount of exhaust gas discharged can be further reduced.

FIG. 7 is a sectional view similar to FIG. 2 in the fourth embodiment. Only the differences from the first embodiment will be described below. In this embodiment, the exhaust upstream side end surfaces of the first and second annular portions 31 and 32 are curved surfaces that are connected to the end surfaces of the third annular portion 33 and that curve in the exhaust downstream direction. Even with this configuration, the exhaust gas easily flows into the third annular portion 33, which is intended to generate heat, and the same effect can be obtained.

FIG. 8 is a sectional view similar to FIG. 2 in the fifth embodiment. Only the differences from the first embodiment will be described below. In the present embodiment, the exhaust upstream side end faces of the first and second annular portions 31 and 32 are curved surfaces that are connected to the end faces of the third annular portion 33 and that curve in the exhaust upstream direction. Even with this configuration, the exhaust gas easily flows into the third annular portion 33, which is intended to generate heat, and the same effect can be obtained. The exhaust upstream side end face shapes of the first and second annular portions 31 and 32 in the present embodiment and the fourth embodiment can of course be applied to the second and third embodiments.

In all the examples, when a part of the exhaust upstream side end surface of the catalyst carrier is formed into an inclined surface or a curved surface, the bonding area of the metal foil increases correspondingly, so that the rigidity of the catalyst carrier can be increased. it can. FIG. 9 shows the configuration of FIG. 2 in the sixth embodiment.
It is a sectional view similar to FIG. As in this embodiment, the first and second
By making both end surfaces of the annular portions 31 and 32 into inclined surfaces, the rigidity of the catalyst carrier can be made stronger.

Further, the discharge joining on the exhaust upstream side end faces of the first and second annular portions, which are the non-heat generating portions, has been carried out in the past, and no cost increase occurs in all the embodiments.

[0023]

As described above, according to the catalyst carrier of the electric heating type catalytic converter according to the present invention, in the catalyst carrier which causes only the specific portion to generate heat, the portion on the exhaust upstream side end face where the specific portion is located is concave. Since the inclined surface or the curved surface is formed on at least a part of the boundary with the other portion, the exhaust gas easily concentrates on the specific portion due to the inclined surface or the curved surface, and the entire catalyst carrier. It is possible to reduce the amount of exhaust gas that passes through a portion other than the specific portion and is discharged unpurified in a relatively short time until the activation temperature reaches the activation temperature.

[Brief description of drawings]

FIG. 1 is a front view showing a first embodiment of a catalyst carrier of an electric heating type catalytic converter according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a front view showing a second embodiment of a catalyst carrier of an electric heating type catalytic converter according to the present invention.

FIG. 4 is a sectional view taken along line BB of FIG.

FIG. 5 is a front view showing a third embodiment of the catalyst carrier of the electric heating type catalytic converter according to the present invention.

6 is a cross-sectional view taken along line CC of FIG.

FIG. 7 is a sectional view similar to FIG. 2, showing a fourth embodiment of the catalyst carrier of the electric heating type catalytic converter according to the present invention.

FIG. 8 is a sectional view similar to FIG. 2, showing a fifth embodiment of the catalyst carrier of the electric heating type catalytic converter according to the present invention.

FIG. 9 is a sectional view similar to FIG. 2, showing a sixth embodiment of the catalyst carrier of the electric heating type catalytic converter according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Center electrode 2 ... Outer cylinder 3 ... Metal foil 33 ... 3rd annular part 33a, 33a '... Specific part

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F01N 3/20 ZAB K (72) Inventor Masahiko Koporu 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Corporation Stock In-house (72) Inventor Osamu Fujishiro 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Japan Auto Parts Research Institute, Inc. (72) Inventor Yuzuru Yoshinaga 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Japan Auto Parts Co., Ltd. In the laboratory

Claims (1)

[Claims] 1. A catalyst carrier comprising a metal foil carrying a catalyst laminated between both electrodes, wherein a short circuit and insulation in the thickness direction of the metal foil are devised to generate heat only in a specific portion, The exhaust upstream side end surface of the carrier has a concave portion where the specific portion is located, and an inclined surface or a curved surface is formed at least at a part of a boundary with another portion. Catalyst carrier for exothermic catalytic converter.