JPS6332887Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an exhaust gas treatment device for a diesel engine, and more specifically, to treat carbon particles and similar particulate matter (hereinafter referred to as exhaust particulates) contained in exhaust gas. The present invention relates to an exhaust particulate purification device suitable for collecting exhaust particulates on an appropriate collection material by a physical method, synchronously incinerating the collected exhaust particulates, and regenerating the collection material.

Prior Art Most of this type of exhaust particulate is flammable, such as carbon particles, and diesel putty collects such combustible particulates and incinerates the collected particulates to regenerate the collection material. Various curate traps are known. An electric heater is generally used as a means for burning the collected particulate and regenerating the trap. That is, an electric heater is attached to the front end surface of the collection material, and the heater burns the exhaust particulates adhering to the surface of the collection material, and uses this as a heat source to make the downstream particulates natural.

On the other hand, ceramic heaters have been developed and put into practical use as heaters in recent years, but these are made by printing patterns of high-melting point metals such as tungsten or molybdenum as conductors inside highly electrically insulating alumina ceramics and sintering them to create a heater structure. It is. Alternatively, ceramic heaters that generate heat themselves have been developed, which are formed by sintering alumina (Al ₂ O ₃ ) powder with titanium carbide (T ₁ C) or titanium nitride (T ₁ N) powder. . Since the shape, width, thickness, etc. of this ceramic heater can be freely selected, the degree of freedom in design is increased, and it has the advantage that it has excellent heating characteristics and can be manufactured easily.

On the other hand, ceramic heaters have the disadvantage of poor impact resistance due to the material they are made of. Therefore, if the ceramic heater is fully attached to the trap material, it will receive direct vibration from the trap material (engine vibration, vibration from the vehicle road surface, vibration due to the way the trap material or heater is installed, etc.), resulting in damage to the heater or damage to the mounting area. Looseness may occur.

Therefore, when using a ceramic heater, it has been proposed to assemble it away from the trap material rather than in full contact with the trap material. However, if the heater is placed too far away from the trap material, the particulate collected on the trap material cannot be ignited, and therefore, dimensional control of the gap between the heater and the trap material is very important. Therefore, it is necessary to improve the adhesion or compatibility between the heater and the trap material from the two viewpoints of improving the ignitability of the heater and preventing breakage of the heater.

Purpose of the invention In view of the above, the present invention improves the adhesion between the ceramic heater and the trap material, and improves the fit of the joint between the two, thereby preventing the heater from breaking and improving its ignitability. The purpose is to measure improvement.

According to the present invention, in order to achieve the above-mentioned objects, a large number of irregularities are formed on the surface of the ceramic heater facing the trap material, and these irregularities are smoothly connected to the mesh structure of the trap material. The presence of these irregularities makes it possible to increase the amount of particulate matter deposited.

Example This will be explained below with reference to the drawings.

FIG. 1 shows the overall structure of an exhaust particulate purification device according to the present invention, and a trap container 1 has a trap material 3 therein. As the trap material 3, known foamed ceramic or similar materials can be used. That is, the trap material 3 has a three-dimensional mesh structure, through which the exhaust gas can flow, and exhaust particles contained in the exhaust gas can be collected between the meshes.

The trap container 1 is arranged in the exhaust line 5 of a diesel engine. It is assumed that the exhaust gas flows in the direction of the arrow in FIG.

A plate-shaped ceramic electric heater 10 is provided at the inlet side (upstream side) end of the trap container 1, if necessary, for igniting and burning the exhaust particulate collected in the trap material 3 to regenerate the trap.

The ceramic heater 10 is, for example, six approximately dogleg-shaped plate-shaped heaters arranged radially at appropriate intervals at the inlet of the collection material 3 as shown in FIG. Exhaust gas flows through the gap 19 between each ceramic heater.
and flows through the spaces 9, 15 of each ceramic heater itself.

Each ceramic heater 10 is, as is known in the art, a suitable electrical heating element, such as tungsten, wrapped in aluminum foil and coated with ceramic. Alternatively, as described above, a ceramic heater formed by sintering Al ₂ O ₃ powder and T ₁ C or T ₁ N powder may be used. The shape, size, number, and arrangement of the ceramic heaters 10 are arbitrarily selected so as not to impede the flow of exhaust gas and to minimize the increase in back pressure of exhaust gas.
Moreover, if the ceramic heater 10 supports a catalyst, ignition can be performed more smoothly, and ignition energy (power consumption) can also be reduced.
Each ceramic heater 10 has its outer peripheral portion 10, for example.
A is held by an annular holding insulator 21 or the like to be integrated and fixed to the trap container 1.

According to the present invention, a large number of irregularities 13 are formed on the inner surface of each ceramic heater 10, that is, on the surface facing the trap material 3. The unevenness 13 has, for example, the same roughness (distribution) as the number of meshes of the trap material 3 or is finer than that, and the depth of the unevenness is, for example, about 1 mm. By doing so, when the heater is assembled into the trap container, the irregularities on the heater surface enter between the meshes of the trap material 3 and are embedded in the meshes of the trap material, so that the connection between the heater and the trap material is ensured. Furthermore, if the heater and the trap material are pressed against each other and then rotated slightly relative to each other, the protrusions of the unevenness 13 that are biting into the trap material may be partially broken, or the trap material may be located exactly on the mesh lattice. The tips of the protrusions are beveled so that the joint between the heater and the trap material will fit better. Preferably, the protrusions forming the uneven surface 13 of the heater are tapered as shown in FIG. 4, and cut into the mesh of the trap material 3 by half of its height (approximately 0.5 mm). By doing this, a predetermined gap l (FIG. 1) is formed between the heater surface and the opposite surface of the trap material, and the particulate is effectively adhered to this space as shown at 17. That is, the peripheral surface of the protrusion of the unevenness 13 also contributes to an increase in the adhesion surface area to which the particulate is adhered. The particulate 17 bridges the heater 10 and the trapping material 3, so when the heater 10 is energized, the particulate 17 and the particulate at the upstream end of the trapping material 3 are ignited, and as far as the ignitability of the heater is concerned, the heater 10 is connected to the trapping material. It can be considered equivalent to having the entire surface adhered.

Effects of the Invention As described above, according to the present invention, instead of bringing the heater into full contact with the trap material 3, a space for adhesion of particulate is formed between the two, thereby preventing the heater from breaking without impairing the ignitability of the heater. It is something that can be measured. Furthermore, since the heater comes into point contact with the trap material 3 at many points, it can be expected that the heater surface will be prevented from being damaged by the trap material.

[Brief explanation of drawings]

FIG. 1 is a partially sectional side view showing the overall structure of the exhaust particulate purification device according to the present invention, FIG. 2 is a front view showing a part of the heater used in the present invention, and FIG. 3 is the same as FIG. 1. Enlarged view of part A, Figure 4 is the 3rd
Enlarged view of the main part of the figure. 1... Trap container, 3... Trap material, 10
...Ceramic heater, 13...Unevenness.

Claims (1)

[Scope of utility model registration request] A trap material with a mesh structure is installed in the exhaust gas path of a diesel engine to collect exhaust particulates.
A diesel engine exhaust particulate purification device comprising a ceramic heater disposed on the upstream end face of the trap material, characterized in that a large number of irregularities are formed on the surface of the ceramic heater facing the trap material.