JPH087053Y2 - Particulate filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is provided with an exhaust system of a diesel engine to collect solid fine particles, that is, particulates in exhaust gas, and to further embed electrical power embedded in a plug member. Energize the heater wire
The present invention relates to a particulate filter that periodically burns and regenerates the collected particulates by heating.

[Conventional technology]

Due to incomplete combustion in diesel engines, the exhaust gas contains a large amount of particulates that are a source of black smoke. Therefore, in a vehicle equipped with such an engine, in order to remove particulates in the exhaust gas, a particulate filter made of a material having air permeability such as ceramics is arranged in the exhaust system.

By the way, since the particulate filter gradually loses its air permeability and eventually becomes clogged with the collection of particulates, the particulate filter must be regenerated at an appropriate time. That is, the filter regeneration treatment means incineration of the accumulated particulates.

There are various methods for incineration of particulates. For example, in Japanese Patent Laid-Open No. 64-69712, an electric heater wire is embedded in a plug member that seals the ends of a large number of passages forming a filter, and an appropriate time is set. There is disclosed an exhaust gas purification device that ignites and burns particulates by energizing and heating the electric heater wire.

[Problems to be solved by the device]

By the way, in the particulate filter used in the above-mentioned exhaust gas purification device, since the length of the electric heater wire embedded in each plug member is embedded with a substantially equal length over the entire surface of the filter, the heater energization is performed. At this time, the amount of heat generated becomes even over the entire surface of the filter. However, due to the arrangement structure of each plug member in the particulate filter, the degree of heat radiation to the outside of the filter container becomes higher toward the outer peripheral portion of the filter, so even if the plug member is heated with the same calorific value as described above, the filter center There is a temperature difference between the filter and the outer periphery of the filter, and the particulates collected on the outer periphery of the filter cannot be ignited due to insufficient ignition energy, or cracks may occur inside the filter due to thermal strain due to the temperature difference. is there.

In view of such problems, it is an object of the present invention to provide a particulate filter that makes the temperature difference between the central portion and the outer peripheral portion of the filter smaller than that of the particulate filter during filter regeneration.

[Means for solving the problem]

To achieve the above object, according to the present invention, a large number of exhausts are defined by air-permeable partition walls, the exhaust upstream end is open and the exhaust downstream end is sealed by a plug member. It consists of an inlet passage and a number of exhaust outlet passages whose exhaust upstream end is sealed by a plug member and whose exhaust downstream end is open. An electric heater wire is embedded in either one of the above passage members. Thus, in a cylindrical particulate filter that collects fine particles in exhaust gas discharged from a diesel engine, an electric heater wire embedded in a plug member on an outer peripheral portion of the particulate filter is connected to a plug in a central portion of the filter. Provided is a particulate filter characterized in that it is embedded deeper toward a passage end that is open than an electric heater wire embedded in a member.

[Action]

Since the electric heater wire is embedded deeper in the outer peripheral part, the amount of heat generated increases from the central part of the filter by the length of the increased heater wire. The difference in temperature between the outer part and the outer part is reduced.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a particulate filter according to the present invention,
It is a block diagram applied to an exhaust gas purification device of a so-called reverse flow regeneration system in which the flow direction of exhaust gas at the time of particulate collection is opposite to the flow direction of exhaust gas at the time of filter regeneration.

In the figure, 1 is a cylindrical particulate filter (or filter), 2 is a particulate filter 1
, 3a and 3b represent exhaust pipes connected to the front and rear ends of the trap container 2, respectively.
When collecting particulates, the exhaust gas flows from the exhaust pipe 3a toward the exhaust pipe 3b (in the direction of the solid line arrow in the figure), and during the regeneration process of the particulate filter 1, the exhaust gas for regeneration for propagating particulate combustion. Reversely flows from the exhaust pipe 3b toward the exhaust pipe 3a (in the same direction as the dotted arrow). In this specification, the normal flow of exhaust gas during particulate collection is referred to as the end facing the exhaust pipe 3a as the exhaust upstream end of the filter 1, and the end facing the exhaust pipe 3b is referred to as the filter. It will be called the end portion on the exhaust gas downstream side.

As shown in FIG. 1 in a partially enlarged manner, the inside of the particulate filter 1 has an exhaust inlet passage 4 having an open end on the exhaust upstream side and an exhaust gas having an open end on the exhaust downstream side. The outlet passage 5 is partitioned adjacent to each other by a partition wall 6 having good air permeability, which is represented by a porous material such as ceramics.

Further, the end of the exhaust inlet passage 4 on the exhaust downstream side and the end of the exhaust outlet passage 5 on the exhaust upstream side are sealed by plug members 7 and 8, respectively. Therefore, when collecting particulates, The exhaust gas that has flowed into the exhaust inlet passage 4 through the opening end portion of the exhaust inlet passage 4 passes through the partition wall 6 and then from the opening end portion on the exhaust downstream side of the exhaust outlet passage 5 to the exhaust pipe 3b. It flows. That is, a large amount of particulates in the exhaust gas adhere to the inner wall of the exhaust inlet passage 4 in the process of passing through the filter 1.

In order to incinerate the particulates collected inside the filter 1 in this way, an electric heater wire 9 is embedded in the plug member 7 that seals the end of the exhaust inlet passage 4 on the exhaust downstream side. This electric heater wire 9 is connected to an electric heater wire 9 embedded in a different plug member 7, and finally one end of the electric heater wire 9 is connected to a battery via a relay 11 whose operation is controlled by a control circuit 10. 12 and the other end is grounded.

As described above, at the time of filter regeneration, contrary to the case of particulate collection, the filter regeneration exhaust gas flows into the exhaust outlet passage 5 through the exhaust downstream side opening end of the exhaust outlet passage 5. After passing through the partition wall 6, the exhaust gas flows from the open end of the exhaust gas inlet passage 4 on the upstream side of the exhaust gas to the exhaust pipe 3a. At this time, the electric heater wire 9 is energized and heated by the control circuit 10, and as a result, the particulates collected inside the exhaust inlet passage 4 are ignited, and the combustion propagation of the particulates is promoted along with the flow of the exhaust gas for regeneration. It is done.

FIG. 2 is a view of the end face on the exhaust downstream side of the particulate filter 1 from which the trap container 2 is removed, viewed from the exhaust pipe 3b side. In the figure, an arrangement example of the plug member 7 is shown in the upper half thereof, and the connection state of the electric heater wire 9 is also shown.

Particulate filter 1 wired as described above
Therefore, according to the present embodiment, as shown in FIG. 3 along the line III-III in FIG. 2, the electric heater wire embedded in the plug member 7 located on the outer peripheral portion 1a of the particulate filter 1 is used. 9 is set longer than the electric heater wire 9 embedded in the plug member 7 located in the central portion 1b of the particulate filter 1, and is directed toward the inside of the filter 1, in other words, at the end of the open passage 4. It is wired so that it protrudes deeper than the target. Therefore, as shown in the figure, when the lengths of the plug members 7 arranged in the filter central portion 1b and the filter outer peripheral portion 1a are made equal, the electric heater wire 9 of the filter outer peripheral portion 1a penetrates the plug member 7 and the heater During energization, the filter outer peripheral portion 1a generates more heat by the increased length.

As a result, when the heater is energized, the outer periphery of the filter 1a is surrounded by the trap container 2 (not shown), so that a large amount of heat is radiated (dissipated) to the trap container 2 side. It is possible to maintain a high temperature due to the amount of heat generation, and it is also possible to secure ignitability and combustion propagation to the particulates collected in the filter outer peripheral portion 1a. In addition, the temperature rise of the outer peripheral portion 1a, as a whole, has a temperature difference with the filter central portion 1b as compared with the conventional filter,
Therefore, it is possible to reduce the number of cracks, and thus it is possible to prevent the occurrence of cracks due to a large temperature difference.

FIGS. 4 and 5 show a modified embodiment having a slightly different structure from the above-described FIG. 3 embodiment.

In the embodiment shown in FIG. 4, the length of the plug member 7'arranged in the vicinity of the filter outer peripheral portion 1a is made longer than that of the plug member 7 arranged in the filter central portion 1b. In addition to the effect of the embodiment shown in FIG. 3 described above, the length of the particulate collection portion of the exhaust inlet passage 4'of the outer peripheral portion 1a is set to the central portion.
It is shorter than that of 1b, and thus the combustion propagation length at the time of filter regeneration is shortened to make it more difficult for the flame to blow out on the way.

In the embodiment shown in FIG. 5, the length of the plug member 7 is gradually lengthened from the filter central portion 1b to the filter outer peripheral portion 1a so that a more uniform temperature distribution is obtained over the entire filter area during regeneration. The electric heater wire 9 is formed so that the electric heater wire 9 to be embedded is also embedded deeper toward the filter outer peripheral portion 1a.

Although the respective embodiments of the present invention have been described above by taking the example of a cross section of the filter into two equal parts, it goes without saying that in other cross sections not shown, the electric heater wire similarly located in the outer peripheral portion of the filter is It is buried deeper into the filter than the electric heater wire located in the center of the filter. Further, in the present embodiment, the particulate filter applied to the exhaust gas purifying apparatus of the backflow regeneration type has been described as an example, but the exhaust gas flow direction during particulate collection and the exhaust gas flow direction during particulate filter regeneration are the same. Become,
The same can be applied to a particulate filter used in a so-called forward flow regeneration type exhaust emission control device.

[Effect of device]

As described above, according to the present invention, since the electric heater wire is embedded deeper in the outer peripheral portion of the filter, the temperature difference between the central portion of the filter and the outer peripheral portion is reduced, and cracks are less likely to occur. Further, the outer peripheral portion of the filter, which has been relatively difficult to be regenerated so far, is likely to be regenerated as the temperature rises during regeneration.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an exhaust emission control device equipped with a particulate filter according to the present invention; FIG. 2 is an external view of an end portion on the exhaust downstream side of the particulate filter shown in FIG. 1, and FIG. 2 Partial sectional view of the filter along the line III-III; FIG. 4 is a partial sectional view of a filter as a second embodiment different from the embodiment shown in FIG. 3; FIG. 5 is FIG. FIG. 7 is a partial cross-sectional view similar to FIG. 1 ... particulate filter, 1a ... filter outer peripheral portion, 1b ... filter central portion, 4 ... exhaust inlet passage, 5 ...
Exhaust outlet passage, 6 ... Partition wall, 7,8 ... Plug member, 9 ...
Electric heater wire.

Claims (1)

[Scope of utility model registration request] 1. A large number of exhaust gas inlet passages defined by gas-permeable partition walls, having an exhaust gas upstream end opening and an exhaust gas downstream end sealed by a plug member, and an exhaust gas upstream passage. It consists of a number of exhaust outlet passages whose ends are sealed by plug members and whose ends on the exhaust downstream side are open.Electrical heater wire is embedded in one of the plug members of the above passages, so that it is discharged from the diesel engine. In a cylindrical particulate filter that collects fine particles in exhaust gas, the electric heater wire embedded in the plug member at the outer peripheral portion of the particulate filter is replaced by an electric heater wire embedded in the plug member in the central portion of the filter. Particulate filter characterized by being buried deeper toward the end of the open passage.