JPH0618028Y2 - Reverse-flow regeneration type diesel particulate purification device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a particulate purification device for a diesel engine.

[Conventional technology]

In order to prevent exhaust particulates (diesel particulates) such as carbon particles contained in the exhaust gas of diesel engines from being released into the atmosphere, a honeycomb filter made of ceramic is placed in the exhaust passage to collect the exhaust particulates. This is well known. This filter will clog during long use and must be regenerated. For this reason, a heater is provided on the exhaust gas upstream side of the filter, and the electric heater is energized at predetermined intervals to burn the flammable particulates such as carbon particles captured by the filter, thereby regenerating the filter. You can However, when the regeneration filter is regenerated, the heater is energized to burn the particulates.
In this case, the heater is arranged near the end surface of the filter so as to be orthogonal to the flow of exhaust gas. This heater is made of nichrome wire, etc.
The heater is divided into a plurality of portions through a plurality of insulators, and each divided heater is configured to ignite and burn particulates collected in a filter portion facing the heater and extending in the filter longitudinal axis direction. Reproduction)
-78918 gazette).

[Problems to be solved by the device]

By the way, in the particulate purification apparatus of the reverse flow regeneration system disclosed in Japanese Patent Laid-Open No. 61-22325, five pieces of the exhaust gas flow direction at the time of collecting particulates and the exhaust gas flow direction at the time of regeneration are set to be opposite to each other. Switching valves are used, and each switching valve requires its own actuator. Therefore, when a large number of switching valves are used in this way, there is a problem that the structure becomes complicated, the mountability on a vehicle is deteriorated, and the weight is increased.

In addition, in the filter, the heater heat transfer to the inside of the filter cell (inlet passage), which tends to accumulate a large amount of particulates, occurs because the heater-side end of the filter cell is sealed by the plug member. In particular, the filter portion extending in the filter longitudinal axis direction facing the above-mentioned insulator does not have a heater in the vicinity of the end face thereof, and therefore, the pattern portion deposited on that portion is not formed. It was difficult to ignite and burn the curate.
The present invention is provided in view of the above problems of the conventional device.

[Means for Solving the Problems]

In order to solve the above problems, according to the present invention, a honeycomb filter for collecting exhaust particulates of a diesel engine, and particulates collected in opposing filter portions arranged in the vicinity of an end face on the exhaust downstream side of the filter are provided. A plurality of heaters for igniting the heater, and a plurality of insulators disposed between the heaters and supporting the heaters to enable the heater end face to be divided and arranged in the vicinity of the filter end surface, and the upstream side position of the particulate filter and A bypass passage connected to the exhaust passage is provided at a position downstream of the heater, and a first opening / closing valve is arranged in the exhaust passage between the upstream connection position and the particulate filter. A first operating position that closes the bypass passage and opens the exhaust passage, and the exhaust passage upstream of the downstream passage from the connecting position of the bypass passage. And a second opening / closing valve that communicates with the exhaust passage downstream of the downstream connecting position and that occupies a second operating position that reduces the passage area of the exhaust passage. Bypass passage portion communicating between the exhaust passage between the first on-off valve and the particulate filter and the exhaust passage on the downstream side of the downstream connecting position at the second operating position of the second on-off valve. A backflow passage that communicates with the exhaust gas is provided so that the exhaust gas flows from the filter to the heater when collecting particulates, and the exhaust gas flows from the heater to the filter via the bypass passage when the particulate incineration filter is regenerated. A diesel particulate purification device of a regeneration type, wherein a heat transfer plate having a large number of pores is inserted between the heater and the filter, and the heat transfer plate is positioned in the vicinity of the insulator. The that pores, its axis diesel particulate purification apparatus, wherein a inclined form in order to direct the filter portion facing the insulator is provided.

[Action]

Since the second opening / closing valve that doubles as the opening / closing of the bypass passage and the backflow passage is provided at the connection position on the downstream side of the filter, only one valve is conventionally provided for opening / closing each passage. or,
Since the second opening / closing valve reduces the passage area of the exhaust passage when the bypass passage and the exhaust passage communicate with each other, the exhaust gas can be branched to the filter side and the downstream side only by this. The two valves required for can be unitized.

Further, in the filter, the heat energy from the heater is made uniform by inserting the heat transfer plate between the heater and the filter. In addition, some of the pores formed in the heat transfer plate,
By forming the axis so as to be inclined so as to direct the filter portion facing the insulator, the regeneration gas passing through the heat transfer plate is deflected toward the filter portion, and the heat energy from the heater is particulated in the filter. To facilitate ignition and combustion.

〔Example〕

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an exhaust system portion of a diesel engine equipped with a reverse-flow regeneration type diesel particulate purification device according to the present invention, and an exhaust pipe 10 indicates exhaust gas from a diesel engine (not shown) by an arrow. It extends so as to flow in the direction shown. The exhaust pipe 10 is branched into an exhaust main pipe (exhaust passage) 12 and a bypass pipe (bypass passage) 14. The exhaust main pipe 12 is divided and supported by a honeycomb filter 16 made of, for example, a ceramic material for collecting particulates, a heat transfer plate 17 described later, and a plurality of insulators 18 for dividing and regenerating the filter 16. A trap container 20 accommodating a heater 19 and a heater 19 is installed in this order. The bypass pipe 14 is connected to the exhaust main pipe 2 at a connection position 22 on the upstream side of the trap container 20 and a connection position 24 on the downstream side of the heater 19.

A first opening / closing valve 26, which is a butterfly valve, is arranged in the exhaust main pipe 12 between the upstream connecting position 22 and the particulate filter 16. Further, the second opening / closing valve 28 is arranged at the downstream connecting position 24.

The first opening / closing valve 26 and the second opening / closing valve 28 are rotatable around valve shafts 27 and 29 perpendicular to the plane of the drawing when viewed in the figure,
It can occupy a first operating position that is substantially horizontal as shown and a second operating position that is shown in dotted lines.
In the first actuated position, the first on-off valve 26 opens the exhaust main 12, while the second on-off valve 28 opens the bypass pipe 14.
Is closed and the exhaust main 12 is opened. This state shows a state in which the particulate matter in the exhaust gas is collected by the filter 16, and the exhaust gas flows in the direction shown by the solid line arrow in the figure.

In the second operating position, the lower half of the second opening / closing valve 28 can close the lower half of the bypass pipe 14, but the other part of the bypass pipe 14 communicates with the exhaust main 12.
Therefore, the bypass pipe 14 includes the exhaust main pipe 12 (on the side of the trap container 20) upstream of the downstream connecting position 24 and the exhaust main pipe 12 (of the second opening / closing valve 28) downstream of the downstream connecting position 24. The downstream side). At this time, the second on-off valve 28 projects into the exhaust main 12, and the flow area of the exhaust gas toward the trap container 20 is reduced by reducing the passage area of the exhaust main 12 toward the wake side of the second on-off valve 28. Back pressure to
Allows the exhaust gas to pass through the filter 16 at the desired rate. The angle of the second opening / closing valve 28 and the shape of the shielding plate 30 are determined in order to control the flow of the exhaust gas through the filter 16 while reducing the passage area of the exhaust main pipe 12.
Preferably, the shape of the shielding plate 30 is set so that the flow rate of the exhaust gas toward the trap container 20 is one-tenth of the exhaust gas discharge amount, and the remaining exhaust gas is directly discharged during the regeneration process. It

Further, a backflow passage pipe 32 (backflow passage) is provided to connect the exhaust main pipe 12 between the first on-off valve 26 and the particulate filter 16 and the other portion closed by the second on-off valve 28. To be That is, the first on-off valve 2 shown by the dotted line
In the operating position of 6, the exhaust main pipe 12 is closed, exhaust gas from the engine is caused to flow into the bypass pipe 14, and the second opening / closing valve 28
A part of the exhaust gas branched by the filter 16 and flowing through the filter 16 is caused to flow into the reverse flow passage pipe 32. In this state, the heater 19 is heated to incinerate the particulates in the filter 16. This shows a so-called regeneration processing state, and the exhaust gas flows in the direction of the dotted arrow in the figure. In addition, the backflow passage pipe 3
The downstream opening 32b of No. 2 is controlled by the second opening / closing valve 28, and in the second operating position, the passage pipe 32 is provided.
The regenerated exhaust gas that has passed through flows directly to the downstream side.

Further, in order to drive the first on-off valve 26 and the second on-off valve 28 respectively, the negative pressure actuated actuators 34, 3
6 and solenoid valves 38, 40 are provided.

Solenoid valves 38, 40 Engine control computer 4
The operating negative pressure or the atmospheric air can be selectively supplied to the actuators 34 and 36 in accordance with the output from 2. For example, when the operating negative pressure is supplied to the actuators 34 and 36, the first opening / closing valve 26 and the second The on-off valve 28 can be rotated to the second operating position. In addition, the electric heater 18
Can also be energized via a relay 44 controlled by the computer 42. In addition, 46 is a battery.

As described above, according to the present embodiment, the first opening / closing valve 26 is arranged in the exhaust passage 12 between the upstream side connection position 22 of the bypass passage 14 and the particulate filter 1, and the first open / close valve 26 is provided at the downstream side connection position 24. A first operating position (solid line) that closes the bypass passage 14 and opens the exhaust passage 12;
4 is connected to the exhaust passage 12 on the upstream side of the downstream connecting position 24 and the exhaust passage 12 on the downstream side of the downstream connecting position 24, and a second operating position for reducing the passage area of the exhaust passage 12 ( And a second opening / closing valve 28 occupying the exhaust passage 12 between the first opening / closing valve 26 and the particulate filter 1 and the second operating position of the second opening / closing valve 28. Since the backflow passage 32 communicating with the bypass passage communicating with the exhaust passage 12 on the downstream side of the connection position 24 is provided, the backflow regeneration processing of the particulate filter is performed only by the two opening / closing valves 26 and 28. Therefore, the configuration as a whole can be simplified and the mountability on the vehicle can be improved. Further, since the backflow passage 32 opens into the bypass passage 14, the second opening / closing valve 28 closes the backflow passage 32 at the same time when the bypass passage 14 is closed, and the second opening / closing valve 28 is made small. Will be able to.

FIG. 2 is an external view of the above-described trap container 20 as viewed from the heater arrangement side.

According to this embodiment, the heater 19 has six heater wires 19a, 19b, 19c, 19d, 1 arranged in a fan-shaped region formed by dividing the heater 19 into six equal parts in the angular direction on the plane orthogonal to the exhaust flow.
It consists of 9e and 19f. This heater wire 19a, b, c,
Each of d, e, and f is arranged in a meandering manner by six insulators 18 serving as heater holders arranged radially from the central portion, and one end of each heater wire 19 is connected to the relay 44 (first
(Fig.), The other end is collected in the central portion and connected to the ground electrode 48. When the filter is regenerated, the heater wires 19a, b, c,
The d, e, and f are successively energized by the relay 44 to generate heat, and the particulates deposited on the filter portion located behind the heater wire are incinerated via the exhaust gas passing through the heater 19. Therefore, as described above, conventionally, the heat energy from the heater 19 is not well transferred to the filter portion which is not covered with the heater 19, that is, the filter portion which faces the six insulators 18 in this embodiment, resulting in poor reproduction. The possibility was great.

FIG. 3 is a partial cross-sectional view of the trap container 20 on the heater arrangement side taken along the line III-III in FIG. 2. According to the present embodiment, the heater 19 and the filter 1 are provided as means for solving the above-mentioned problems.
A heat transfer plate 17 having a large number of pores 49 arranged over the entire surface is interposed between the heat transfer plate 17 and the plate 6. The heat transfer plate 17 includes a heater 19
The heat capacity is small (thin plate shape) so that the heat energy from the filter is transferred to as many filters 16 as possible, and it is made of a material having good thermal conductivity. Its outer shape disperses the heat energy in unnecessary portions. In order to prevent this from occurring, it is divided corresponding to the heater arrangement and formed into a fan shape. Therefore, in this embodiment, the heat transfer plates 17 are composed of six pieces, and each heat transfer plate 17 has a small heat conductivity, such as ceramic, in order to minimize heat transfer to unnecessary parts, that is, parts other than the filter. In the illustrated embodiment, each heat transfer plate 17 is preferably held by a plurality of protrusions 18 a provided on the insulator 18 and a plurality of protrusions 1 provided on the end face of the filter 16.
It is held by 6a. In addition to this, for holding the heat transfer plate, a part of the plug 50 that seals each filter cell is formed to extend from the end face of the filter, and the heat transfer plate 1 is formed at that part.
7 may be held (not shown).

4 and 5 are external views of the above-mentioned heat transfer plate 17 as seen from the heater side, and a filter having a cross section taken along line VV in FIG. 4 that passes through the pores 49 of the heat transfer plate 17. FIG.

As described above, each heat transfer plate 17 is formed in a fan shape,
Although a large number of pores 49 are provided over the entire surface, the pores 4
As shown in the figure, the cross section of 9 forms a pore 49 arranged in the vicinity of the insulator 18 with an inclination such that its axis 49a is directed to the filter portion 16 '(shaded portion in the figure) facing the insulator 18. . However, as shown by the arrow in the figure, when the exhaust gas passing through the heater 19 passes through the fine holes 49 during filter regeneration, part of the action is deflected by the direction of the fine holes 49 and is covered by the heater 19. By introducing the high-temperature regenerated exhaust gas to the unexposed filter portion 16 ', it becomes possible to easily ignite and burn the particulate matter accumulated in this portion.

The inclined formation of the pores 49 is not limited to the illustrated cross section, and all the pores 49 located in the vicinity of the insulator 18 are applicable, and naturally, all the pores arranged on the filter end face are arranged. It is applied to the heat transfer plate 17 of FIG.

As described above, good filter regeneration is achieved over the entire filter 16.

〔effect〕

ADVANTAGE OF THE INVENTION According to this invention, the backflow regeneration process of a particulate filter can be performed only with a 1st on-off valve and a 2nd on-off valve, and the whole structure can be simplified and the mountability in a vehicle can be improved. it can. Further, since the backflow passage opens to the bypass passage, the second on-off valve closes the backflow passage at the same time when the bypass passage is closed, so that the second on-off valve can be made small. . In addition, the high-temperature regeneration gas is also supplied to the insulator facing filter portion, which had been in the tendency of regeneration failure in the filter, so that the regeneration of the filter is surely executed (the remaining unburned particulates are reduced). When the filter is regenerated, the particulate combustion heat does not increase, and problems such as filter melting damage due to overheating are eliminated. In addition, according to the present invention, the heat transfer plate having a large number of pores acts as a straightening plate for the exhaust gas passing through the filter when collecting particulates, so that the pressure distribution in the filter becomes uniform and the exhaust gas is exhausted. Since the gas will flow into the filter uniformly, the particulates will be evenly deposited throughout the filter, and as a result, during filter regeneration,
There is no local excessive temperature rise, and like the above effect, problems such as melting loss are eliminated (improved durability).

[Brief description of drawings]

FIG. 1 is a diagram showing an engine exhaust system equipped with a reverse flow regeneration type diesel particulate purification device according to the present invention;
FIG. 2 is an external view of the particulate trap container as seen from the heater arrangement side; FIG. 3 is a partial sectional view of the trap container along the line III-III in FIG. 2; and FIG. 4 is a heat transfer plate according to the present invention. FIG. 5 is a filter cross-sectional view including a heat transfer plate cross-section taken along line VV in FIG. 4. 16 ... Filter, 17 ... Heat transfer plate, 18 ... Insulator, 19 ... Heater, 49 ... Pore.

Claims (1)

[Scope of utility model registration request] 1. A honeycomb filter for collecting exhaust particulates of a diesel engine, and a plurality of heaters arranged in the vicinity of an end face on the exhaust downstream side of the filter to ignite the particulates collected in opposed filter portions. , A plurality of insulators arranged between the heaters and supporting the heaters to enable the heater end face to be arranged in the vicinity of the filter end face at a position upstream of the particulate filter and a position downstream of the heater. A bypass passage connected to the exhaust passage is provided, and a first opening / closing valve is arranged in the exhaust passage between the upstream connection position and the particulate filter, and the bypass is provided at the downstream connection position. A first operating position that closes the passage and opens the exhaust passage, and the exhaust passage on the upstream side of the bypass passage and the connecting position on the downstream side of the downstream coupling position More communicates with the exhaust gas passage downstream, placing a second on-off valve occupying a second operating position and a small passage area of the exhaust passage, further, the first
An exhaust passage between the on-off valve and the particulate filter, and a bypass passage portion communicating with the exhaust passage on the downstream side of the downstream connecting position at the second operating position of the second on-off valve. A reverse flow passage that connects the exhaust gas and the exhaust gas flows from the filter to the heater when collecting particulates, so that the exhaust gas flows from the heater to the filter through the bypass passage when the particulate incineration filter is regenerated. In the diesel particulate purifying apparatus of the method, between the heater and the filter, a heat transfer plate having a large number of pores is inserted, and further the pores located near the insulator of the heat transfer plate are A diesel particulate purification device, wherein an axis is formed so as to be inclined so as to direct the filter portion facing the insulator.