JPH062527A - Exhaust gas purifying device for internal combustion engine - Google Patents

Abstract

(57) [Summary] [Purpose] It is an object of the present invention to provide an exhaust emission control device capable of preventing drivability after the operation of the exhaust brake is released as much as possible. [Structure] There is an exhaust brake 30 on the upstream side of the exhaust passage,
There is a branch passage on the downstream side that merges after branching, there are particulate filters 5A and 5B in each branch passage, and there are flow path switching valves V1 and V2 at the branch and merge parts of each branch passage, respectively. In an exhaust gas purification apparatus for an internal combustion engine that collects particulates in the filter and alternately regenerates the filters 5A, 5B, a pressure loss value detection means for detecting pressure loss values ΔP on the upstream and downstream sides of the filters 5A, 5B, and a filter. Regeneration detecting means for detecting whether or not the exhaust brake 30 is being regenerated, exhaust brake operation detecting means for detecting the operating state of the exhaust brake 30, and a filter whose pressure loss value is a predetermined value or less when the exhaust brake 30 is not operating. Flow control valve 1, V
And a flow path switching means for switching between the two.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purification apparatus for an internal combustion engine, and more particularly, in a diesel engine having an exhaust brake provided upstream of the exhaust gas purification apparatus, after the exhaust brake is released and the exhaust brake is deactivated. The present invention relates to an exhaust emission control device for an internal combustion engine that does not deteriorate drivability.

[0002]

2. Description of the Related Art Exhaust gas of an internal combustion engine of an automobile or the like, especially a diesel engine, contains exhaust particulates (particulates) containing carbon as a main component, which is a cause of exhaust black smoke. From the viewpoint of environmental pollution, it is desirable to remove the particulates. In recent years, it has been proposed to dispose a diesel particulate by this filter by disposing a ceramic filter in the exhaust passage of the diesel engine.

As described above, in the exhaust gas purifying apparatus for an internal combustion engine in which the particulates in the exhaust gas are removed by the filter, the air permeability is gradually increased when the amount of the particulates trapped inside the filter increases as the filter is used. Lost,
Since the engine performance will be deteriorated, it is necessary to periodically burn and regenerate the particulates collected in the filter.

Generally, in the conventional exhaust gas purifying apparatus for an internal combustion engine, when the particulate filter loses air permeability and the pressure of the exhaust gas on the upstream side of the filter becomes larger than the pressure on the downstream side by a predetermined value or more ( When the pressure loss value exceeds a predetermined value) is detected by the pressure sensor, and the particulate regeneration process is performed. In this regeneration process, an electric heater usually provided in the vicinity of the filter is energized, or the particulates ignited by igniting the burner are ignited, and a regeneration gas such as secondary air is evacuated from the air pump in the vicinity of the filter. Is performed to burn the particulates.

By the way, in a diesel engine, the above-mentioned exhaust gas purification device may be installed downstream of the exhaust brake device provided in the exhaust passage. For example, JP-A-3
Japanese Patent Publication No. 151528 discloses an exhaust system in which a particulate filter is provided in each of two exhaust pipes, and an exhaust brake is provided on the upstream side of each filter. Is shown to be closed.

[0006]

SUMMARY OF THE INVENTION However, Japanese Unexamined Patent Publication No.
In the exhaust device of Japanese Patent No. 151528, when the exhaust brake is released after being actuated, the drivability may change depending on the amount of particulates trapped in the filter. That is, when the amount of particulates trapped in the filter is small, the exhaust brake is deactivated as before, but when the amount of particulates trapped in the filter is large, after releasing the exhaust brake. The air permeability of the particulate filter is poor, so the exhaust gas pressure increased by the operation of the exhaust brake does not drop sharply even after the exhaust brake is released, and the brake cannot be completely released, resulting in drivability. It gets worse.

Therefore, the present invention solves the problems of the conventional exhaust gas purifying apparatus for an internal combustion engine, and provides an exhaust gas purifying apparatus capable of preventing deterioration of drivability after releasing the operation of the exhaust brake as much as possible. The purpose is to

[0008]

The exhaust gas purifying apparatus for an internal combustion engine according to the first aspect of the present invention which achieves the above object has a plurality of filters provided with a filter for collecting particulates in the exhaust passage of the internal combustion engine. An exhaust gas purification device for an internal combustion engine, in which a branch passage is provided, and a passage switching valve is provided in the vicinity of the branch portion of each branch passage, and particulates are alternately collected by a plurality of filters and the filters are alternately regenerated. In, the exhaust brake means for reducing the opening area of the exhaust passage as compared with before the operation of the exhaust brake, the pressure loss value detecting means for detecting the pressure loss value of the filter, and after the operation of the exhaust brake, once the pressure loss value It is characterized in that a flow path switching means for allowing exhaust gas to flow into the small filter is provided.

In the exhaust gas purifying apparatus for an internal combustion engine according to the second aspect of the present invention which achieves the above-mentioned object, an exhaust brake is provided on the upstream side of the exhaust passage of the internal combustion engine, and a plurality of branches are joined on the downstream side after branching. A passage is provided, a filter for collecting particulates is provided in each branch passage, and a flow path switching valve is provided at each of the branch portion and the merging portion of each branch passage. In an exhaust gas purification apparatus for an internal combustion engine that collects and alternately regenerates a filter, a pressure loss value detection unit that detects a pressure loss value of the filter, and a regeneration detection unit that detects whether or not the filter is regenerating, Exhaust brake operation detection means for detecting the operation state of the exhaust brake, and the exhaust gas is applied to a filter whose pressure loss value is a predetermined value or less when the exhaust brake is operating while the filter is not regenerating There has been characterized by providing a flow path switching means for switching the flow path switching valve so as to flow into.

[0010]

According to the exhaust gas purifying apparatus for an internal combustion engine of the second aspect of the present invention, a plurality of branch passages provided with a filter for collecting particulates are provided in the middle of the exhaust passage of the internal combustion engine. A flow path switching valve is provided in the vicinity of the branch part of the exhaust gas purification device for an internal combustion engine, which collects particulates alternately by a plurality of filters and alternately regenerates the filter. The opening area of the exhaust passage is made smaller than that before the operation, the pressure loss value of the filter is detected by the pressure loss value detecting means, and after the operation of the exhaust brake by the flow path switching means, once,
Exhaust gas is introduced into the filter having the smallest pressure loss value.

According to the exhaust gas purifying apparatus for an internal combustion engine of the second aspect of the present invention, a plurality of branch passages are provided on the downstream side of the exhaust brake so as to merge after branching, and the respective branch passages are used for collecting particulates. A plurality of filters are provided, and a flow path switching valve is provided at each of the branch portion and the merging portion of each branch passage, and the plurality of filters alternately collects particulates and alternately regenerates the internal combustion engine. In the exhaust gas purification device, the pressure loss value of the filter, whether or not the filter is being regenerated, and the operation state of the exhaust brake are detected. The exhaust gas flows into the filter whose pressure loss value is equal to or less than the predetermined value by switching the above.

As a result, the exhaust gas whose pressure is increased when the exhaust brake is actuated is rapidly discharged through the filter having good air permeability, so that the feeling when releasing the operation of the exhaust brake is not deteriorated. In addition, the number of operation times of the flow path switching means is greater than the one that does not switch the flow path when the pressure loss value of the filter in the trapped state is less than or equal to a predetermined value, as compared with the one in which the exhaust gas flows through the filter with the smallest pressure loss value. Is less.

[0013]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is an exhaust purification device 2 of a reverse flow alternate regeneration dual filter type of the present invention applied to a diesel engine 1 in which an exhaust pipe 2 is provided with an exhaust brake device 30.
0 shows a schematic configuration of one embodiment of No. 0. The exhaust brake device 30 incorporates a butterfly valve 31, and the rotation of the valve 31 temporarily blocks the flow of exhaust gas in the exhaust pipe 2 to brake the engine 1.

The exhaust emission control device 20 of the diesel engine of this embodiment includes an exhaust pipe 2 downstream of the exhaust brake device 30.
The exhaust pipe 2 for guiding the exhaust gas from the engine 1 is branched into branch pipes 2A and 2B at a branch portion a, and then joined at a joining portion b to be connected to the muffler 6. A first filter 5A and a second filter 5B are provided in the casings 3A and 3B provided in the middle of the branch pipes 2A and 2B, respectively, in order to collect particulates in the exhaust gas. This first filter 5
A honeycomb filter including a large number of filter cells is used as the A and second filters 5B, and the exhaust upstream end and the downstream end of each filter cell are alternately plugged with plugs. Therefore, the particulates in the exhaust gas flowing into the first filter 5A and the second filter 5B are collected in the filter cell when the exhaust gas passes through the wall surface of the filter cell.

A pressure sensor SPU is provided upstream of the branch portion a of the branch pipes 2A and 2B, and a pressure sensor SPD is provided downstream of the confluence portion b. The pressure difference (pressure loss value or pressure difference) between the upstream and downstream sides of the first and second filters 5A and 5B is obtained by inputting the outputs of the pressure sensors SPU and SPD to the ECU (control circuit) 100. The control circuit 100 controls the first and second filters 5 based on this differential pressure.
Determine the regeneration time for A and 5B.

In this embodiment, the pressure loss value of the filter is determined by the differential pressure. However, the pressure loss value is not limited to the differential pressure, but the amount of particulates in the filter can be detected by the energization resistance or the vehicle. It can be estimated from parameters such as the traveled distance, the integrated rotation speed, and the load condition. On the other hand, a plug member (not shown) near the downstream end faces of the first and second filters 5A and 5B, or a plug member (not shown) at the downstream end is an electric heater HA that heats the filters to ignite particulates during filter regeneration. And HB are provided, and these electric heaters H
One ends of A and HB are grounded, and the other ends thereof are connected to the battery 11 via switches SWA and SWB controlled by the control circuit 100. Further, although not shown in this figure, a vehicle speed sensor for detecting the speed of the vehicle and an accelerator opening sensor for detecting the accelerator opening are provided, and a vehicle speed signal V from the vehicle speed sensor and an accelerator opening sensor are provided. The accelerator opening signal θ is also input to the control circuit 100.

During regeneration of the first and second filters 5A and 5B, the electric heater HA or HB is energized, and the first filter 5A or the second filter 5A or 2B on the energized side is energized.
It is necessary to flow the regeneration gas from the downstream side of the filter 5B and discharge the combustion gas from the upstream side thereof. Therefore, in this embodiment, the regeneration gas supply port 17 is provided at the joining portion b of the branch pipes 2A and 2B, and the regeneration gas supply port 17 is provided.
As a regeneration gas from the electric air pump 9 through a regeneration gas supply passage 7 provided with an on-off valve V3 on the way.
Next air is supplied. Both the electric air pump 9 and the on-off valve V3 are drive-controlled by the control circuit 100. A regeneration gas discharge port 18 is provided at the branch portion a of the branch pipes 2A and 2B. One end of the regeneration gas discharge port 18 is open to the atmosphere, and the on-off valve V
The regeneration gas discharge passage 8 provided with 4 is connected. The on-off valve V4 is also drive-controlled by the control circuit 100.

At the branch portion a where the regeneration gas discharge port 18 opens, the exhaust pipe 2 and the branch pipe 2 upstream of the branch portion a.
A first control valve V1 for switching the connection of A, 2B and the regeneration gas discharge port 18 is provided, and the regeneration gas supply port 17 is provided.
A second control valve V2 that switches the connection of the exhaust pipe 2, the branch pipes 2A and 2B, and the regeneration gas supply port 17 on the downstream side of the merging portion b is provided in the merging portion b that opens.

The first and second control valves V1 and V2 are both driven by a control circuit (ECU) 100, and the first and second control valves V1 and V2 are controlled by a control signal from the control circuit 100. Are linked to be positioned at the solid line position C, the broken line position B, and the alternate long and short dash line position B. Further, the exhaust brake device 30 provided on the upstream side of the exhaust gas purification device 20 is also controlled to be opened / closed by a control signal from the control circuit 100. The valves V1 to V4 and the butterfly valve 31 of the exhaust brake device 30 are actually driven by a diaphragm actuator, a negative pressure switching valve, or an electric actuator, but the drive mechanism thereof is not particularly limited. Therefore, the illustration and the description thereof are omitted here.

FIGS. 9 and 10 show an example of the actual construction of the first and second control valves V1 and V2. For example, butterfly valves are used as the first and second control valves V1 and V2, and rotary shafts 10a and 11a provided near the openings of the regeneration gas discharge port 18 and the regeneration gas supply port 17 are used.
By rotating the valve bodies 10b and 11b around the center, the regeneration gas discharge port 18 and the regeneration gas supply port 17 can be opened to either one of the branch pipes 2A and 2B. .

The dashed line position B of the first and second control valves V1 and V2 is the position where the second filter 5B is in the trapped state, and the exhaust gas from the engine 1 flows through the second filter 5B and passes through the muffler 6. Are released into the atmosphere. At this time, the on-off valves V3 and V4 are closed when the first filter 5A is not being regenerated, but the on-off valves V3 and V4 are closed when the first filter 5A is being regenerated.
3, V4 is opened and the heater HA is energized,
The regeneration gas from the air pump 9 flows from the supply port 17 through the first filter 5A to assist the combustion of particulates, and the combustion gas is discharged from the discharge port 18 into the atmosphere.

The broken line positions B of the first and second control valves V1 and V2 are the positions where the first filter 5A is in the trapped state, and the exhaust gas from the engine 1 flows through the first filter 5A and passes through the muffler 6. Emitted into the atmosphere. At this time, the open / close valves V3 and V4 are closed when the second filter 5B is not being regenerated, but the open / close valves V3 and V4 are closed when the second filter 5B is being regenerated.
4 is opened and the heater HB is energized, the regeneration gas from the air pump 9 flows from the supply port 17 through the second filter 5B to assist the combustion of particulates, and the combustion gas is discharged from the discharge port 18 to the atmosphere. Is discharged.

In the exhaust emission control system 20 for a diesel engine constructed as described above, one embodiment of the operation when the exhaust brake system 30 provided on the upstream side is operated will be described with reference to FIG. Although not shown, it is assumed that the vehicle speed V, the accelerator opening θ, and the pressure values PU and PD on the upstream and downstream sides of the filters 5A and 5B are read at predetermined time intervals.

In the exhaust emission control device 20 to which the present invention is applied, as described above, the first and second filters 5A and 5B alternately collect the gas. And in this control, the first,
Since control is not performed when one of the second filters 5A and 5B is in the process of reproduction, it is first determined in step 201 whether the filter 5A or 5B is being reproduced.
This routine is ended during reproduction.

On the other hand, when neither filter is being regenerated, the routine proceeds to step 202, where the pressure difference ΔP is calculated from the pressure values PU and PD on the upstream and downstream sides of the filters 5A and 5B. Then, in step 203, when the differential pressure ΔP is smaller than the predetermined value P1, the process returns to step 202 while maintaining the current state. Therefore, even if the exhaust brake device 30 is operated during this period, the collection state of the filter 5A or the filter 5B does not change. If ΔP ≧ P1 at step 203, the routine proceeds to step 204, where it is judged if the value of the differential pressure ΔP is smaller than another predetermined value P2 which is larger than the predetermined value P1.
This predetermined value P2 indicates the filter regeneration timing. When ΔP ≧ P2, the routine proceeds to step 205, where the filter regeneration processing is executed.

If ΔP <P2 at step 204, the routine proceeds to step 206, where it is judged if the exhaust brake device 30 has been operated. When the exhaust brake device 30 is not operated, the process returns to step 202, and when the exhaust brake device 30 is operated, the process proceeds to step 207. Step 207 is for determining whether or not the first filter 5A is trapped and concentrated when the exhaust brake device 30 is operated. When the first filter 5A is trapped and concentrated, step 2 is performed.
08, when the second filter 5B is trapped and concentrated, the process proceeds to step 212.

In step 208 which is carried out when the first filter 5A is trapped and concentrated, the first and second control valves V1 and V2 are controlled to the position i, and the exhaust gas passage is particulated during the operation of the exhaust brake device 30. Filter 5B that did not collect particulates from the collecting and collecting filter 5A side
Switched to the side. As a result, the exhaust brake device 30
After the operation of (3) is released, the exhaust gas flows through the filter 5B in which particulates are not collected. In the following step 209, it is determined whether or not the exhaust brake device 30 has been deactivated, and when it is deactivated, the step 210
Then, it is determined whether or not 3 seconds have elapsed since the operation was released. When the exhaust brake device 30 has not been deactivated in step 209, and when 3 seconds have not elapsed after the exhaust brake device 30 has been deactivated in step 210, the process returns to step 209. After 3 seconds have passed since the exhaust brake device 30 was deactivated, the step 2
From 10 to step 211, the first and second control valves V
1, V2 are controlled to the collection position B before the operation of the exhaust brake device 30, and this routine is finished.

In step 212, which is executed when the second filter 5B is trapped and concentrated, the first and second control valves V1 and V2 are controlled to the positions b, and the exhaust gas passage is particulated during the operation of the exhaust brake device 30. Filter 5A that did not collect particulates from the collecting and collecting filter 5B side
Switched to the side. As a result, the exhaust brake device 30
After the operation of (3) is released, the exhaust gas flows through the filter 5A in which particulates are not collected. In the following step 213, it is determined whether or not the exhaust brake device 30 has been deactivated, and if it has been deactivated, a step 214
Then, it is determined whether or not 3 seconds have elapsed since the operation was released. When the exhaust brake device 30 has not been deactivated in step 213 and when 3 seconds have not elapsed after the exhaust brake device 30 has been deactivated in step 214, the process returns to step 213. Also, the exhaust brake device 3
Step 3 after 3 seconds have passed since 0 was released
4 to step 215, the first and second control valves V1,
V2 is controlled to the collection position A before the operation of the exhaust brake device 30, and this routine ends.

As described above, in the exhaust emission control system for the internal combustion engine of the above-described embodiment, when the amount of particulates collected by the trapping filter is small, the exhaust gas emission amount is reduced regardless of the operation of the exhaust brake device 30. The flow passage is not changed, and when the amount of the particulates collected by the collecting filter is larger than the predetermined value, the flow passage of the exhaust gas is changed during the operation of the exhaust brake device 30, and the exhaust brake device 30 is changed. When the operation is canceled, the exhaust gas stored on the upstream side of the exhaust brake device 30 flows for a predetermined time into the filter that has not collected the particulates until then.

The reason why the flow path of the exhaust gas is changed when the exhaust brake device 30 operates as described above will be described below. FIG. 3 is a diagram for explaining the value of the front-rear differential pressure ΔP of the filter in the exhaust emission control device 20 of FIG. 1 and the sensation felt by the driver during operation of the exhaust brake device 30, and FIG. 4 is a diagram for explaining the particulate matter in the filter. It is a figure explaining the relationship between the amount of collection and filter differential pressure deltaP. Assuming that P0 is the differential pressure of the filter at the start of collection, the filter differential pressure ΔP increases as the collection amount of particulates in the filter increases, the differential pressure becomes P1 at the collection amount A, and the collection amount B The differential pressure becomes P2. Differential pressure Δ
The time when P becomes P2 is the regeneration time of the filter. Then, until the collected amount reaches A, as shown in FIG. 3, even if the exhaust brake device 30 is operated during this period, the driver does not feel any braking abnormality and the collected amount exceeds A. It is known that the driver actually feels a braking abnormality when the exhaust brake device 30 is operated.

As shown in FIG. 5, the amount of collected particulates in the filter is small and the back pressure value is P1 +.
When the exhaust brake device 30 operates in a state of a smaller than Pa (Pa is atmospheric pressure), the back pressure fluctuates in the order of a → c → a ′, but at this time, the driver does not feel any discomfort. On the other hand, when the exhaust brake device 30 operates in a state where the amount of collected particulates in the filter is large and the value of the back pressure is larger than P1 + Pa, the back pressure is b → c → b ′.
However, at this time, the inertial feeling after the release of the exhaust brake device 30 is different from the back pressure a, and the driver feels uncomfortable. Therefore, in the present invention, when the exhaust brake device 30 is operated with the back pressure a, it is left as it is, and when the exhaust brake device 30 is operated with the back pressure b, the exhaust gas is released after the operation is released. It is made to flow through a filter with a small amount of particulate collection, and the back pressure is b →
The exhaust brake device 30 can always be used with the same feeling by setting c → a ′ or b → c → d (where d is the back pressure of the filter in which no particulate matter is collected). It was done.

FIGS. 6 (a) to 6 (c) are diagrams for explaining the operation of the above-described embodiment in time when the first filter 5A is trapped and concentrated and the trapped amount is smaller than A shown in FIG. Is. (a)
Shows the state where the exhaust brake device 30 is not operated, and the first and second control valves V1 and V2 are in the position B of FIG. (b) shows the state where the exhaust brake device 30 is operated in the state of (a), and the first and second control valves V1 and V2 are shown.
Is unchanged from position b in FIG. (c) shows a state in which the exhaust brake device 30 has been deactivated, and the first and second control valves V1 and V2 are in the positions B of FIG. 1, so that the exhaust gas passes through the first filter 5A for collecting and concentrating exhaust gas. Exhausted through.

FIGS. 7 (a) to 7 (c) are diagrams for explaining the operation of the above-described embodiment in time when the first filter 5A is trapped and concentrated, and the trapped amount is larger than A shown in FIG. Is. (a) shows a state where the exhaust brake device 30 is not operated, and the first and second control valves V1 and V2 are in the position B of FIG. (b) shows the state where the exhaust brake device 30 is operated in the state of (a), and the first and second control valves V1 and V2 are shown from the position b of FIG. 1 (the position of the broken line in FIG. 7). It is changed to the position 1 of 1 (the position of the solid line in FIG. 7). (c) shows a state in which the exhaust brake device 30 has been deactivated, and since the first and second control valves V1 and V2 are in the position a in FIG. 1,
Exhaust gas does not pass through the first filter 5A that had been trapped and concentrated,
It is discharged through the second filter 5B that was not trapped and concentrated. The state of (c) is released after a predetermined time, for example, 3 seconds, in which the back pressure increased by the exhaust brake device 30 returns to a normal state, and returns to the state of (a).

In the control of FIG. 2, when one of the filters is trapped and concentrated and the trapped amount is smaller than A shown in FIG. 4, the positions of the first and second control valves V1 and V2 are changed. However, the positions of the first and second control valves V1 and V2 may be changed to the non-focusing side. Next, the present invention,
Normally, alternate collection is performed, and when the diesel engine is in a high load state, it is temporarily switched to simultaneous collection, that is, the positions of the first and second control valves V1 and V2 in FIG. The control when applied to the switching exhaust emission control device will be described with reference to FIG. In addition, in the control procedure of FIG.
When the diesel engine is not in the high load state, the same control as the control procedure described in FIG. 2 is performed, and therefore, the same control is given the same step number.

The embodiment of FIG. 8 differs from the control of the embodiment of FIG. 2 in that the accelerator opening θ for judging the load of the engine is read in step 202 of FIG. 2, and steps 204 and 206. In that point, steps 801 to 805 for determining whether the engine is in a high load state are inserted, and the procedure after step 206 is not different from the above-described embodiment.

In step 201, the filter 5A or 5
It is determined whether or not B is being reproduced. If B is being reproduced, this routine is ended, and if not being reproduced, the routine proceeds to step 202 '. In step 202 ', the accelerator opening θ is read, and the differential pressure ΔP is calculated from the pressure values PU, PD on the upstream and downstream sides of the filters 5A, 5B. Then, in step 203, when the pressure difference ΔP is smaller than the predetermined value P1, the current state is maintained and the process returns to step 202 ′. Therefore,
Even if the exhaust brake device 30 is activated during this period,
Even if the engine is in the high load state, the collection state of the filter 5A or the filter 5B does not change.

If ΔP ≧ P1 at step 203, the routine proceeds to step 204, where it is judged if the value of the differential pressure ΔP is smaller than another predetermined value P2 which is larger than the predetermined value P1. This predetermined value P2 indicates the regeneration time of the filter, and Δ
When P ≧ P2, the routine proceeds to step 205, where filter regeneration processing is executed. ΔP <P2 in step 204
In the case of, the routine proceeds to step 801, where the accelerator opening θ is 80
It is determined whether or not it is at least%. When θ <80%, it is determined that the engine is not under high load and the routine proceeds to step 206, where θ ≧ 8
If it is 0%, it is judged that the engine has a high load and step 8
After proceeding to 02, the current positions of the first and second control valves V1 and V2 are stored, and then both are controlled to the position c in FIG.
In this state, the exhaust gas is the first and second filters 5A and 5B.
Will flow to both. In the following step 206, it is determined whether or not the exhaust brake device 30 has been operated.
Then, when the exhaust brake device 30 is not operated, the routine proceeds to step 803, and when the exhaust brake device 30 is operated, the routine proceeds to step 207.

In step 803, the accelerator opening θ is 80
It is determined whether or not it is less than%, and if θ ≧ 80% before, the process returns to step 802, and if θ <80%, the process proceeds to step 804. In step 804, it is determined whether the positions of the first and second control valves V1 and V2 are c. This is because the process may proceed to step 804 without passing through step 802. When the positions of the first and second control valves V1 and V2 are not c, the exhaust brake device 30 in step 206 of FIG. The process returns to step 202 'as in the operation. On the other hand, in step 804, the first and second control valves V
When it is determined that the positions of 1 and V2 are C, step 8
The process proceeds to step 05 and returns them to the original positions stored in step 802, and then returns to step 202 '.

In step 207, which is executed when it is determined in step 206 that the exhaust brake device 30 has been actuated, it is determined whether the first filter 5A is trapped and concentrated when the exhaust brake device 30 is actuated. This determination is made in step 802 by using the first and second control valves V1, V1.
When the position 2 is controlled to C, the position stored before the control is performed. When the first filter 5A is trapped and concentrated, the routine proceeds to step 208, and when the second filter 5B is trapped and concentrated, the routine proceeds to step 212.

Steps after step 208 are the same as those described with reference to FIG. 2, and a filter different from the filter collecting particulates before the exhaust brake device 30 is operated while the exhaust brake device 30 is operated. The exhaust gas passage is switched by the first and second control valves V1 and V2, and three seconds after the operation of the exhaust brake device 30 is released, the exhaust gas passage is switched to the filter side that was collecting the particulates before the operation. To be

As described above, in the exhaust gas purifying apparatus for an internal combustion engine of the embodiment shown in FIG. 8, when the amount of particulates trapped by the trapping filter is small, the engine is under a high load and the exhaust brake device 30. The flow path of the exhaust gas is not changed regardless of the operation of. Further, when the amount of particulates collected by the filter for collecting and concentrating exceeds a predetermined value and is large, the flow path of the exhaust gas is expanded and the filter 5 is expanded when the engine is under a high load.
Simultaneous collection of A and 5B occurs, and when the load on the engine is reduced, the original collection is restored. Then, when the amount of the particulates collected by the filter for collecting and concentrating exceeds a predetermined value and is large, the flow path of the exhaust gas is changed to the side of the filter having the smaller collecting amount when the exhaust brake device 30 operates. When releasing the operation of the brake device 30, the first and second control valves V1 and V2 are returned to their original trapped positions in anticipation of the time when the back pressure has decreased. As a result, the driver does not feel uncomfortable when the exhaust brake device 30 operates.

In the above explanation, the present invention will be described.
The embodiment of the reverse flow alternate regeneration dual filter type exhaust purification device 20 applied to the diesel engine 1 in which the exhaust pipe 2 is provided with the exhaust brake device 30 has been described, but the present invention is directed to the exhaust gas flow of which the heater is a filter. On the other hand, it is also applicable to the forward flow regeneration system on the upstream side.

[0043]

As described above, according to the present invention, in a diesel engine equipped with an exhaust brake and an exhaust purification device, it is possible to prevent deterioration of drivability after the release of the operation of the exhaust brake as much as possible. effective. Also, compared to when exhaust gas is passed through the filter with the smallest pressure loss value when the exhaust brake operates,
If the flow path is not switched when the pressure loss value of the filter in the collecting state is less than or equal to a predetermined value, the number of times of operation of the flow path switching means is reduced, and the problem of the conventional technique can be solved.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration example of an exhaust gas purification apparatus of a reverse flow alternate regeneration dual filter type to which the present invention is applied.

FIG. 2 is a flowchart showing an operation when the exhaust brake of FIG. 1 is operated.

3 is a diagram illustrating a value of a differential pressure across the filter in the exhaust emission control device of FIG. 1 and a sensation felt by a driver during operation of the exhaust brake device.

FIG. 4 is a diagram illustrating a relationship between a trapped amount of particulates in a filter and a filter differential pressure.

FIG. 5 is a diagram showing a change in back pressure during operation of the exhaust brake device depending on the amount of collected particulate matter in the filter.

6 (a) to (c) show that the first filter in FIG. 1 is trapped and concentrated,
It is a schematic diagram which demonstrates the operation | movement of the Example of FIG. 2 over time when the collection amount is smaller than A shown in FIG.

7 (a) to (c) show that the first filter in FIG. 1 is trapped and concentrated,
It is a schematic diagram which demonstrates operation | movement of the Example of FIG. 2 over time when the collection amount is larger than A shown in FIG.

8 is a flowchart showing a control procedure when the control of the present invention is applied to the exhaust gas purification apparatus shown in FIG. 1 that performs simultaneous collection when the engine load is high.

FIG. 9 is an enlarged view showing a specific configuration example of the first control valve of FIG.

FIG. 10 is an enlarged view showing a specific configuration example of the second control valve of FIG. 1.

[Explanation of symbols]

 2 ... Exhaust pipe 2A, 2B ... Branch pipe 5A, 5B ... Filter 7 ... Regeneration gas supply passage 8 ... Regeneration gas discharge passage 9 ... Air pump 17 ... Regeneration gas supply port 18 ... Regeneration gas discharge port 30 ... Exhaust brake Device 100 ... Control circuit a ... Branching part b ... Merging part HA, HB ... Electric heater SPU, SPD ... Pressure sensor V1 ... First control valve V2 ... Second control valve V3, V4 ... Open / close valve

Claims (2)

[Claims] 1. A plurality of branch passages provided with a filter for collecting particulates are provided midway in an exhaust passage of an internal combustion engine, and a flow passage switching valve is provided in the vicinity of a branch portion of each branch passage. In an exhaust gas purification apparatus for an internal combustion engine that alternately collects particulates by means of the filter and alternately regenerates the filter, an exhaust brake means for reducing the opening area of the exhaust passage as compared to before the operation of the exhaust brake, and the filter. A pressure loss value detecting means for detecting a pressure loss value of the internal combustion engine, and a flow path switching means for allowing exhaust gas to flow into the filter having the smallest pressure loss value after the operation of the exhaust brake. Exhaust purification device. 2. An exhaust brake is provided upstream of an exhaust passage of an internal combustion engine, a plurality of branch passages are provided downstream thereof, and a filter for collecting particulates is provided in each branch passage. A passage switching valve is provided in the vicinity of the branch portion of the passage, and the particulate matter is alternately collected by a plurality of filters, and in the exhaust gas purification apparatus of the internal combustion engine that alternately regenerates the filter, the pressure loss value of the filter is Pressure loss value detecting means for detecting, regeneration detecting means for detecting whether or not the filter is being regenerated, exhaust brake operation detecting means for detecting an operating state of the exhaust brake, and the exhaust brake of the exhaust brake not being regenerated by the filter. An internal combustion engine, comprising: a flow path switching unit that switches the flow path switching valve so that the exhaust gas flows into a filter having a pressure loss value of a predetermined value or less during operation. Exhaust emission control device of the function.