JPH0710030Y2 - Exhaust gas aftertreatment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is an exhaust gas post-treatment in which a filter for collecting particulates as impurities contained in exhaust gas is provided in an exhaust gas exhaust path. Regarding the device.

[Prior Art] Gas discharged from an engine, particularly a diesel engine for an automobile, contains particulates such as hydrocarbons or soot (carbon) as impurities. A trap filter for collecting the particulates is often provided in the exhaust path for guiding the exhaust gas to the outside in order to remove the particulates.

In such an exhaust gas post-treatment device, for example, the second
As shown in the figure, a trap filter 3 is installed in a case 1 forming an exhaust gas discharge path with a heat insulating material / buffer material 2 interposed therebetween. The trap filter 3 has a large number of passages made of a ceramic material or foam metal, and when exhaust gas passes between adjacent passages, particulates are collected by being attached to the wall surface of the passages. The operation is to be performed. The trapping action purifies the exhaust gas.

On the other hand, particulates are accumulated in the trap filter 3 within a relatively short time. Therefore, the heater 4 is used to burn the accumulated particulates in the gas flow direction of the trap filter 3 (second
It is installed so as to face the front side (in the direction from the left side to the right side in the figure). The heater 4 is formed by bending an electric resistance wire and is provided so as to traverse the inside of the case 1. Then, when the heater 4 is energized at a constant timing, the particulates accumulated in the trap filter 3 are burned and removed by its heat generating action, especially radiant heat, whereby the trapping function of the trap filter 3 is improved. It has been restored to the proper state and maintained in the normal state.

[Problems to be Solved by the Invention] However, the above-mentioned heater 4 is formed to have a size smaller than the inner diameter of the case 1 so as to be separated from the inner wall surface of the case 1, so that the electric heater 4 and the case 1 are electrically connected to each other. Contact is avoided. Therefore, the heater 4 in the conventional apparatus is not formed in a size that covers the entire front surface of the trap filter 3. For this reason, the heating action of the heater 1 is often insufficient, and there is a problem that insufficient heating occurs particularly in the outer peripheral region of the trap filter 3 and an unburned particulate phenomenon occurs. In addition, although the heat insulating material and the cushioning material 2 are wound around the outer periphery of the trap filter 3, since they are arranged so as to be in close contact with the inner wall surface of the case 1, a sufficient heat insulating effect is not obtained. No
Therefore, a sharp temperature drop occurs in the outer peripheral region of the trap filter 3. As a result, the phenomenon of unburned particulates in the outer peripheral region of the trap filter 3 as described above occurs.

Further, when there is a sudden temperature decrease in the outer peripheral region of the trap filter 3 as described above, cracks are easily generated in the trap filter 3 due to an increase in thermal stress due to the temperature gradient, and also in maintaining the durability of the device. It's a problem.

Therefore, the present invention obtains a sufficient heating effect by the heater for burning the particulates accumulated in the trap filter, and sufficiently insulates the trap filter to rapidly reduce the temperature in the outer peripheral region of the trap filter. It is possible to prevent the occurrence of unburned particles of particulates particularly in the outer peripheral region of the trap filter, and to prevent the temperature drop in the outer peripheral region of the trap filter, thereby increasing the thermal stress due to a sharp temperature gradient. It is an object of the present invention to provide an exhaust gas post-treatment device capable of preventing the occurrence of cracks in the trap filter and improving the durability of the device.

[Means for Solving the Problems] In order to achieve the above object, the present invention is provided with a filter for trapping particulates contained in exhaust gas in a case forming an exhaust gas exhaust path, and In an exhaust gas post-treatment device in which a heating heater for burning particulates accumulated in the filter is installed so as to face the front surface of the filter in the gas flow direction, a heat insulating material is attached to the outer periphery of the filter,
The outside of the heat insulating material and the inside surface of the case are arranged with a certain distance therebetween, and an air heat insulating layer is provided between the two, and the heating heater includes the entire front surface of the filter and the air heat insulating layer. The filter is formed to have a size that covers at least a part of the filter, and is installed at a distance from the front surface of the filter.

[Operation] In the means having the above configuration, the heat insulating material is attached to the outer peripheral portion of the filter, and the air heat insulating layer having good heat insulating property is formed between the outer surface of the heat insulating material and the inner surface of the case. Heat is satisfactorily prevented from the outer area of the filter to keep the outer area of the filter warm,
Since it is possible to form and install the heating heater in a size that covers the entire front surface of the filter and at least a part of the air insulating layer by enlarging the case and the heating heater in which the air insulating layer is formed, The heating effect of the heater is sufficiently extended to the outer peripheral area of the filter. Due to the heat retaining action on the filter side and the good heating action on the heater side, the temperature drop in the outer peripheral region of the filter is prevented and the particulates accumulated in the filter are sufficiently burned to the outer peripheral region of the filter. By preventing the temperature drop in the outer peripheral region of the filter, the occurrence of a sharp temperature gradient in the outer peripheral region of the filter is avoided and the thermal stress is prevented from increasing.

[Embodiment] An embodiment of the present invention will be described below in detail with reference to the drawings.

As shown in FIG. 1, a trap filter 13 is installed so as to be supported by a holding member 12 in a hollow cylindrical case 11 that constitutes an exhaust gas discharge path.
The trap filter 13 is housed in the hollow cylindrical main body 12a of the holding member 12 via a heat insulating material / buffer material 12b. The main body 12a of the holding member 12 is coaxially arranged in the case 11, and the main body 12a
Gas distribution direction of a (direction from left side to right side in FIG. 1)
The flange portion 12c provided on the opening edge portion on the rear end side is screwed and fixed to the joint portion 11a of the case 11, whereby the entire holding member 12 is supported in a cantilever manner. There is. The trap filter 13 has a large number of passages made of ceramic material or foam metal, etc., and when exhaust gas passes between adjacent passages, particulates adhere to the wall surface of the passages to collect them. Is being carried out. The trapping action purifies the exhaust gas.

Further, the inner diameter of the case 11 is formed to be larger than the outer diameter of the holding member 12 enclosing the trap filter 13 by a certain amount.
By arranging 12 coaxially, the outer surface of the holding member 12 and the inner surface of the case 11 are separated by a certain distance, and the air heat insulating layer 14 is formed between them. ing.

On the other hand, particulates are accumulated in the trap filter 13 within a relatively short time. Therefore, a heater 15 is installed so as to burn the accumulated particulates so as to face the front side of the trap filter 13 in the gas flow direction (the direction from the left side to the right side in FIG. 1). The heater 15 is formed by bending an electric resistance wire, and the case 11
It is provided so as to traverse inside. Further, the heater 15 is formed and installed in such a size as to cover the entire front surface of the trap filter 13 and at least a part of the air heat insulating layer. Therefore, the heater 15 is configured to face not only the central region of the trap filter 13 but also the peripheral region thereof.

In the apparatus in such an embodiment, when the heater 15 is energized at a constant timing, the particulates accumulated in the trap filter 13 are burned and removed by its heat generating action, especially radiant heat,
As a result, the trapping function of the trap filter 13 is restored to the proper state and the normal state is maintained.

In this case, the outer surface of the trap filter 13 and the case 11
Since the air insulating layer 14 having a good heat insulating property is formed between the inner surface of the trap filter 13 and the inner surface thereof, the heat radiation from the outer region of the trap filter 13 is effectively prevented and the outer region of the trap filter 13 is kept warm. Further, since the air heat insulating layer 14 is formed, the case 11 and the heater 15 can be increased in size to form and install the heater 15 in a size that covers the entire front surface of the trap filter 13. As a result, the heating effect of the heating heater 15 is the trap filter.
It is designed to cover up to 13 outer peripheral areas.

Due to the heat-retaining action on the side of the trap filter 13 and the good heating action on the side of the heater 15, the temperature drop in the outer peripheral region of the trap filter 13 is prevented and the particulates accumulated in the trap filter 13 are trapped in the trap filter 13. It is fully burned to the outer peripheral region. Further, by preventing the temperature decrease in the outer peripheral region of the trap filter 13, a rapid temperature gradient is prevented from being generated in the outer peripheral region of the trap filter 13 and the thermal stress is prevented from increasing.

Incidentally, as in the embodiment, the holding member 12 for accommodating the trap filter 13 is fixed to the case 11 at one place, and if the structure for supporting the trap filter 13 in a cantilevered manner is adopted, Not only can the attachment / detachment be facilitated, the fixed gripping position of the case 11 can be selected more freely than before, and the trap filter can be used without disassembling the fixed gripping member.
It is convenient because it is possible to attach and detach 13.

[Advantages of the Invention] As described above, the present invention enhances the heat retaining effect on the filter side for capturing particulates, and the heating effect on the heating heater side for burning the particulates accumulated in the filter is filtered. A heat insulating material is attached to the outer peripheral portion of the filter so as to extend to the outer peripheral portion of the filter, an air heat insulating layer is formed between the outer surface of the heat insulating material and the inner surface of the case, and the heating heater is attached to the front portion of the filter. Since it has a structure in which it is formed in such a size as to cover the whole of the above and at least a part of the air heat insulating layer and is installed, a sufficient heating action can be obtained by the heater and the heat insulation of the filter is sufficiently performed. This prevents a sudden temperature drop in the outer peripheral area of the filter, especially in the outer peripheral area of the trap filter. It is possible to avoid the occurrence of the unburned residue phenomenon of the particulates. Furthermore, by preventing the temperature from decreasing in the outer peripheral region of the filter, it is possible to prevent an increase in thermal stress due to a sharp temperature gradient, prevent the occurrence of cracks in the filter, and improve the durability of the device.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional explanatory view showing an exhaust gas post-treatment device in an embodiment of the present invention, and FIG. 2 is a vertical cross-sectional explanatory view showing a conventional exhaust gas post-treatment device. 11 ... Case, 13 ... Trap filter, 14 ... Air insulation layer, 15 ... Heater.

Claims (1)

[Scope of utility model registration request] 1. A heater provided with a filter for collecting particulates contained in exhaust gas in a case constituting an exhaust gas discharge path, and a heater for burning particulates accumulated in the filter. In the exhaust gas post-treatment device installed so as to face the front surface of the filter in the gas flow direction, a heat insulating material is attached to the outer peripheral portion of the filter, and the outer surface of the heat insulating material and the inner surface of the case have a constant distance. The heaters are arranged apart from each other, and an air heat insulating layer is provided between them, and the heater is formed in a size that covers the entire front surface of the filter and at least a part of the air heat insulating layer. An exhaust gas post-treatment device, which is installed at a distance from the front part of the exhaust gas.