KR100581182B1 - honeycomb heater - Google Patents

Abstract

The present invention relates to a honeycomb heater. According to the present invention, the outer wall; A front surface into which fluid is introduced; A rear surface from which fluid flows out; And a plurality of longitudinal passages extending from the front to the rear and partitioned by the partitions, wherein the forming honeycomb forms an electrically heatable circuit such that a part of the partitions or a part of the partitions are electrically heated. A front portion having a set of electrode contact portions formed on an outer circumferential surface of the outer wall; A rear portion having another set of electrode contact portions formed on the outer wall outer circumferential surface and having the same thickness as the front portion; and a junction centered on the remaining central axis by slits formed toward the central axis from the outer outer circumferential surface of the honeycomb outer wall, or about the center axis A honeycomb heater is provided, which is made of a connection part made of a surface, and the electric circuit starts from the electrode contact part of the front part and reaches the center part of the front part close to a straight line, and is connected to the electrode contact part of the back part via the connecting part via the center part of the back part.

The honeycomb heater of the new structure is designed to be used as a heater for various fluids because it is capable of intentional heating, such as applying current from the outer wall and opening / closing and concentrating the heating in the center where the passage speed of the fluid is high. It is suitable for use as a heating element of a gas purifier.

Honeycomb Heaters, Longitudinal Passages, Bulkheads

Description

Honeycomb heater

Figure 1a is a front view of a honeycomb heater with a longitudinal slit formed in the prior art

Figure 1b is a perspective view of a honeycomb heater with another prior art transverse slit

Figure 2a is a perspective view of one embodiment in the present invention

FIG. 2B is a front view of FIG. 2A

Figure 2c is a heating distribution diagram of Figure 2b

Description of the main symbols in the drawings

1a: longitudinal slit 1b: transverse slit

2: front electrode contact part 2 ': rear electrode contact part

      5: outer wall 6: longitudinal passage

10: front part 20: rear part

9: connection

The present invention relates to a honeycomb heater.

Honeycomb structures are widely used as catalyst carriers for fluid purification devices because of their smooth mass transfer, large contact area and structural robustness. Also for this reason it can be used variously as a heater of the fluid if heating is possible.

Thermally conductive honeycomb is widely used as a means of initial heating honeycomb in automobile exhaust three-way catalyst system to reduce the so-called "cold start" of the start-up. It is manufactured by lamination.

The method of arranging or stacking one or more metal strips in a spiral with respect to a central axis is a method of inserting an electrode in the central axis and joining another electrode to a cylindrical outer wall to form a circuit and conduct electricity. Metal strips are generally welded and joined to the outer wall or central axis (eg, US Pat. Nos. 5582805, 5866077, 5232671). Such a structure easily constructs a circuit, which is advantageous for uniform heating of the honeycomb, but has a problem in that the electrode of the central axis prevents the flow of fluid in the center and the electrode must be connected and exposed to the outside.

The honeycomb of the lamination method may be formed in an outer circumferential heating method by varying the arrangement. On the other hand, with respect to the exhaust gas purifying apparatus by the non-uniform heating method, US Patent No. 6513324 discloses a method of oxidizing unburned dust collected in a honeycomb filter downstream of the catalytic honeycomb by heating a S-shaped multilayer heater mounted on the rear side of the catalytic honeycomb. It is described. The patent describes that non-uniform heating causes heat conduction to the honeycomb filter by partial oxidation and causes no problem. The S-type heater constitutes an electric circuit that can be easily heated, but in order to support it, the S-type heater must be attached to the catalyst supporting honeycomb on the front surface in a riveted form and there is still a problem of uneven heating.

Korean Patent Laid-Open Publication No. 2003-33382 discloses a method of oxidizing unburned dust collected in a honeycomb filter by arranging a laminated honeycomb of uneven and flat metal strips to form a partial circuit in an insulating jacket and electrically heating the honeycomb. Is starting. However, the structure is too complicated, such as insulation on the circuit and connecting the electrode to the inside.

In addition, the stacking honeycomb is not only a problem of telescoping (protrusion of the center part) due to the separation of fluids, but also a large number of operations such as lamination and brazing because it is mostly laminated with flat strips and conductive uneven strips. Compared to the molding method, the ratio is much higher and precision manufacturing is impossible.

The honeycomb by the molding method is connected between the partition walls and is integrally manufactured by the molding method, so that the structure is solid, the manufacturing labor is small, and the precision manufacturing is possible. Such an integral molding method is manufactured by precision casting or powder molding method. Powder injection molding and in particular extruder molding enable mass production using a wide range of materials. In addition, the honeycomb structure is robust, so there is no problem such as telescoping and there is no obstacle to fluid flow. The honeycomb by the molding method must form a circuit in order to generate heat by the current unit. For this purpose, a slit (or gap) must be formed in the honeycomb in various ways. These slits are broadly divided into longitudinal slits and transverse slits (eg, US Pat. Nos. 5446264, 5318757, 5533167, 5664049, 5852285). However, the slit is not easy to form and the internal oral degree of honeycomb is markedly lowered by the formation of several slits.

SUMMARY OF THE INVENTION An object of the present invention is to provide a catalyst supporting honeycomb heater for automobile exhaust gas purification which is simple in structure, high in oral resistance, economically feasible and precisely manufactured.

Another object of the present invention is to provide a honeycomb heater which can concentrate heating in the center without interfering with the fluid flow.

Still another object of the present invention is to provide a honeycomb heater for exhaust gas purification of a diesel engine which can select a heating unit.

According to the present invention, the outer wall; A front surface into which fluid is introduced; A rear surface from which fluid flows out; And a plurality of longitudinal passages extending from the front to the rear and partitioned by the partitions, wherein the forming honeycomb forms an electrically heatable circuit such that a part of the partitions or a part of the partitions are electrically heated. A front portion having a set of electrode contact portions formed on an outer circumferential surface of the outer wall; A rear portion having another set of electrode contact portions formed on the outer wall outer circumferential surface and having the same thickness as the front portion; and a junction centered on the remaining central axis by slits formed toward the central axis from the outer outer circumferential surface of the honeycomb outer wall, or about the center axis A honeycomb heater is provided, which is made of a connecting portion made of a surface, and the electric circuit starts from the electrode contact portion of the front portion, reaches the center portion of the front portion, and is connected to the electrode contact portion of the rear portion via the connecting portion and through the center portion of the rear portion. The honeycomb heater of the new structure can be used as a heater for various fluids by applying current from the outer wall and opening / closing and concentrating heating in the center of the high flow rate of the fluid. It is suitable for use as a heating element of a gas purifier.

 The honeycomb transverse cross section may be rectangular, circular, elliptical or similar in shape, and the like form includes an incomplete circular or elliptical cross section in a range that does not significantly interfere with the flow of the fluid. The cross section of the longitudinal passage is generally square or hexagonal, but preferably hexagonal having good impact resistance. Preferably, the front and rear surfaces are essentially parallel to each other. The slits of the outer circumferential surface of the outer wall for separating the front part and the rear part are formed toward the center part in the longitudinal middle. Here, the slit refers to a minimum gap for electrically insulating, which may be formed during molding in powder injection molding or molding, and may be formed by diamond saw after molding in extrusion molding. The conductive ceramic material is slurried together with organic and inorganic binders and applied to the joint surface and sintered. When the front and rear parts are separately manufactured and bonded, the conductive material used for the bonding surface is an electrically conductive material forming a honeycomb electric heating unit. Materials having high electrical conductivity and excellent bonding strength are preferred. Brazing, high frequency heating or application and sintering can be applied.

The electrode contact portions are preferably arranged at equal intervals in the outer wall outer periphery of each bath and are made of an electrically conductive material higher than the honeycomb partition material. Thus, the electrode contact portion becomes a starting point through which current flows without a drop in voltage applied to the electrode. The set of electrode contacts consists of two or more, preferably three or more electrode contacts, most preferably four electrode contacts. When the set of electrode contacts in the front part and the set of electrode contacts in the other part of the rear part are crossed with each other, it is advantageous to evenly heat the honeycomb. The set of electrodes connected to the electrode contact portion can be individually supplied with electricity so that it can be partially heated if necessary. Highly conductive materials may be coated on the central portion of the front surface and the central portion of the rear surface to make the heating of the central portion more uniform.

As a method of forming a honeycomb heater, for example, it can be produced by precise casting of a metal. This precision casting method requires melting the material, which limits the use of high melting point ceramic materials. However, it is possible to make honeycomb as various electrothermal materials by incorporating and heating and sintering with an electrically conductive ceramic material such as silicon carbide powder and / or metal powder by powder injection molding or powder extrusion molding. . The electrothermal material is a ceramic material, for example, a negative resistance characteristic (NTC) such as barium titanate of PTC (positive resistance characteristic) material, superconducting oxide of SiC or MoSi ₂ , Y or Bi, perovskite, etc. ), An oxygen ion conductive material such as ZrO ₂ , silicide, boride, nitride, or ion conductive glass material. As the metallic material, Ni, Cr, Fe, Al, etc. are used a lot. Depending on the operating conditions, such as operating temperature, various combinations of metals such as Fe--Cr, Fe--Cr--Al, Ni--Cr, Fe--Al, Fe--Cr or r Ni--Al Combination is possible. In addition, an electrically non-heat resistant resistor material (eg, alumina) may be used with the thermally conductive material.

Since the honeycomb heater of the new structure of the present invention does not form a slit at all except the side slits, the slit is easily formed, and the strength of the slit is not reduced, but it is also advantageous in terms of diffusion of heating by heat conduction. However, there is concern of non-uniform heating such as heating is concentrated in the center part, but it can be alleviated to some extent depending on the arrangement or shape of the electrode contact part. Central heating is preferable because the velocity of exhaust gas passing through the central portion is the highest. Therefore, the honeycomb heater of the present invention is particularly suitable for use in automobile exhaust purification apparatus. In order to remove hydrocarbons, carbon monoxide and nitrogen oxides contained in automobile exhaust gases, so-called three-way catalyst systems carrying ceria, palladium, rhodium and / or platinum are widely used. Generally, the honeycomb heater of the present invention is immersed in a slurry containing a ceramic or an inorganic or organic binder such as an oxide of a metal or metalloid by dipping, spraying, etc., heated, calcined or sintered, and then loaded by reducing the aqueous solution of the platinum group metal. To mount the catalyst. Various methods are disclosed in the supporting method of the catalyst system, and the present invention is not limited to such supporting method.

The honeycomb heater of the new structure of the present invention is particularly suitable for use in a purifier that heats to oxidize fine powder collected in a filter, such as a diesel engine. Various circuit configurations are possible by selecting an electric application electrode.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1A schematically illustrates a conductive honeycomb in which the slits are formed in the longitudinal direction in the prior art. There are many dark areas near the outer edge of the slit and dark areas near the center. 1B discloses a conductive honeycomb in which a slit is formed in the transverse direction in the prior art. There is also a large dark area where no current flows except for the shortest distance. In addition, in the prior art, the internal oral degree of honeycomb is remarkably lowered by the formation of many slits.

2A, 2B and 2C are integrated with the honeycomb front part 10 and the rear part 20 of the honeycomb as an embodiment of the present invention. In this manner, the electrodes are alternated between the electrode contact portion 2 'of the front portion 10 and the electrode contact portion 2' of the rear portion 20 in order to slightly improve the nonuniformity. Figure 2c shows an overview of the heating section of the honeycomb. The honeycomb front part 10 has a side slit 8 formed in the middle thereof, and a circuit is connected by a central connection part 9. The honeycomb does not have a longitudinal slit, but instead has a highly conductive electrode contact portion 2 formed on its outer circumference. On the outer circumferential portion of the honeycomb front portion 10, a highly conductive electrode contact portion 2 'is formed alternately with the electrode contact portion 2 on the front portion. The electric circuit starts from the plurality of electrode contact parts 2 of the honeycomb front part 10 and reaches the center close to a straight line and passes through the center of the honeycomb back part 10 via the central connection part 9 and the electrical contact part 2. Ends with a plurality of staggered electrode contacts 2 '. The outer wall outer peripheral surface slit 8 can be coated with a ceramic material (alumina) and sintered. The honeycomb may be heated by applying a current from the outer circumferential portion, and the honeycomb front portion 10 and the honeycomb rear portion 20 of the honeycomb are integrally manufactured so that the longitudinal passages of the honeycomb coincide. When selected from one set of electrode contact portions 2 and another set of electrode contact portions 2 ′ are energized, partial heating can be achieved.

Since the honeycomb heater of the present invention does not form a slit at all except the side slit, the slit is simple, the structure is simple, the oral resistance is high, and the economical manufacturing is possible, but the precision manufacturing is possible, and the strength decreases due to the compactness of the slit. In addition, it is advantageous in terms of diffusion of heating by heat conduction. In addition, the battery consumption can be minimized as much as the heating contact can be selected by selecting the electrode contact part connected to the electrode, thereby providing a honeycomb heater particularly suitable for exhaust gas purification of diesel engines.

Claims (9)

 Outer walls 5, 5 '; A front surface 7 into which fluid is introduced; A rear surface 7 'at which the fluid flows out; And a plurality of longitudinal passages 6 extending from the front to the back and partitioned by the partitions and forming an electrically heatable circuit such that some of the partitions or some of the partitions are electrically heated. A honeycomb comprising: a front portion (10) having a set of electrode contact portions (2) formed on an outer circumferential surface of an outer wall (5); A rear portion 20 having another set of electrode contact portions 2 'formed on an outer circumferential surface of the outer wall 5' and having the same thickness as the front portion; and a slit 8 formed from the outer circumferential outer surface of the honeycomb toward the central axis. It consists of a connecting portion 9 centered on the remaining central axis, or a joining surface centered on the central axis, and the electric circuit starts at the electrode contact portion of the front portion, reaches the center portion of the front portion, and passes through the connecting portion 9 and the rear portion. Honeycomb heater connected to the electrode contact portion (2 ') of the rear portion through the central portion of. 2. The honeycomb heater according to claim 1, wherein the honeycomb transverse cross-section is rectangular, circular or elliptical in shape and the cross section of the longitudinal passage (6) is rectangular or hexagonal.  3. The honeycomb heater according to claim 2, wherein the electrical contact portion is disconnected from the outer wall outer circumference and disposed at equal intervals and made of an electrically conductive material higher than the honeycomb partition material.  4. The honeycomb heater according to claim 3, wherein electricity is individually applied to a set of electrodes connected to the electrode contact portions (2, 2 ').  5. The honeycomb heater according to claim 4, wherein the pair of electrode contact portions (2) of the front portion (10) and the pair of electrode contact portions (2 ') of the rear portion (20) are crossed with each other. 4. The honeycomb heater according to claim 3, wherein the honeycomb heater is formed by powder forming and sintering an electro-pyrogenic and sinterable powder and / or a metal powder and, if necessary, a non-electrically pyrogenic and sinterable powder.  The honeycomb heater according to claim 2, wherein the honeycomb heater is used for purifying exhaust gas of an internal combustion engine.  8. The honeycomb heater according to claim 7, wherein the internal combustion engine is a diesel engine.  9. The honeycomb heater according to claim 1, wherein a high conductive material is coated on the central portion of the front surface and the central portion of the rear surface.

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