JP2932135B2 - Exhaust particulate removal equipment for diesel engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for removing exhaust particulates of a diesel engine, and more particularly, to the regeneration of a filter for collecting particulates contained in the exhaust gas of a diesel engine. The present invention relates to an exhaust particulate removal device for a diesel engine capable of detecting an abnormality of an exhaust control valve that shuts off inflow.

[0002]

2. Description of the Related Art Exhaust gas from an internal combustion engine such as an automobile, particularly a diesel engine contains exhaust particulates mainly composed of carbon, which causes 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 ceramic filter in an exhaust passage of a diesel engine and remove the diesel particulates with the filter.

[0003] In an exhaust particulate removing device configured to remove particulates by a ceramic filter arranged in an exhaust passage of a diesel engine, the particulates collected inside the particulate filter are used with the use of the particulate filter. When the amount increases, the air permeability gradually decreases, and the engine performance deteriorates. Therefore, it is necessary to periodically regenerate a filter in which particulates are collected to some extent.

[0004] The determination of the regeneration timing is made by detecting the amount of trapped particulates in the filter. The detection of the amount of particulates trapped in the filter is usually performed by detecting the exhaust gas upstream of the particulate filter. And a differential pressure (pressure loss) on the downstream side. That is, it is determined that the regeneration time is reached when the pressure difference becomes larger than a predetermined value.

[0005] In the filter regeneration process, the filter that traps the particulates is generally separated from the exhaust gas flow path by an exhaust shutoff valve, and a regeneration gas, for example, secondary air, is supplied to a filter into which the exhaust gas does not flow. At the same time, the electric heater is energized and heated to ignite the particulates in the filter, which is burned.

For example, Japanese Patent Application Laid-Open No. H4-109019 discloses that secondary air is supplied at the time of regeneration processing in accordance with the differential pressure between the upstream side and the downstream side of the filter, and the secondary air is supplied in a direction opposite to the direction of the exhaust gas flow. An apparatus for performing reproduction is disclosed.

[0007]

However, in a diesel engine exhaust particulate removing apparatus for performing a regenerating process by flowing secondary air in the opposite direction to the exhaust gas flow, the regenerating process is performed due to an abnormality in the exhaust gas shut-off valve. Sometimes, when exhaust gas cannot be completely shut off, the exhaust gas flows into the filter being regenerated, obstructs the flow of secondary air, and there is a problem that unburned fuel due to insufficient secondary air is generated. JP 4
In the technique described in Japanese Patent Application Laid-Open No. 10-90919, the differential pressure between the upstream and downstream of the filter is detected during the regeneration processing. However, there was a risk that such cases could not be adequately dealt with.

In view of the above, the present invention relates to a conventional diesel engine exhaust particulate removal apparatus which is configured to prevent exhaust gas from flowing into a filter being regenerated by using an exhaust cutoff valve during filter regeneration processing. It is an object of the present invention to provide a diesel engine exhaust particulate removing device capable of detecting an abnormality of an exhaust gas cutoff valve.

[0009]

According to a first aspect of the present invention, there is provided a diesel engine exhaust particulate removing apparatus for collecting particulates in exhaust gas by a filter provided in an exhaust passage of the engine. A diesel engine that ignites the particulates collected by the filter and supplies regeneration gas from regeneration gas supply means while the flow of exhaust gas into the filter that has trapped particulates is blocked by the exhaust control valve. In the exhaust particulate removing device, a means for detecting a discharge pressure of the regeneration gas supply means or a pressure on the downstream side of the exhaust control valve, and a means for determining abnormality of the exhaust control valve based on the detected pressure value. It is characterized by having been provided.

[0010]

According to the exhaust particulate removing device for a diesel engine of the present invention, when the filter that captures the particulates in the exhaust gas is regenerated, the filter is operated in a state where the flow of the exhaust gas into the filter is cut off by the exhaust control valve. When the particulates inside are ignited and the regeneration gas is supplied from the regeneration gas supply means, the discharge pressure of the regeneration gas supply means or the pressure downstream of the exhaust control valve is detected, and the detected pressure is detected. An abnormality of the exhaust control valve is determined based on the value.

[0011]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows a schematic configuration of an embodiment of a device 20 for removing exhaust particulates of a diesel engine of a simultaneous trapping and backflow alternate regeneration dual filter type according to the present invention. In the exhaust particulate removal device 20 for a diesel engine of this embodiment, the exhaust pipe 2 for guiding the exhaust gas from the engine 1
At the branch part a, the pipes are branched into branch pipes 2A and 2B, and then merged at the junction part b and connected to the muffler 6. Casing 3 provided in the middle of branch pipes 2A and 2B
A and 3B are provided with a first filter 5A and a second filter 5B, respectively, for collecting particulates in exhaust gas.

Each of the filters 5A and 5B is a honeycomb-shaped filter having a partition wall made of a porous material such as ceramics and generally has a cylindrical shape, and has a large number of rectangular parallelepiped passages (filter cells) surrounded by partition walls. ). The adjacent passages are alternately plugged with ceramic plugs on the exhaust gas inflow side and the exhaust gas outflow side to form a closed passage. Therefore, the particulates in the exhaust gas flowing into the filters 5A and 5B are collected by the filter cells when the exhaust gas passes through the wall surfaces of the filter cells.

Further, pressure introduction pipes SPU and SPD are provided on the upstream side of the branch section a of the branch pipes 2A and 2B and on the downstream side of the junction b, respectively. And the pressure on the downstream side of the junction b. Then, the pressure difference (pressure loss) between the upstream and downstream of the filters 5A and 5B is obtained by the differential pressure sensor 10, and the detected value is input to the ECU (control circuit) 100. The control circuit 100 determines the regeneration timing of the filters 5A and 5B based on the pressure difference (differential pressure).

On the other hand, plugs (not shown) near the downstream end surfaces of the filters 5A and 5B or at the downstream end are provided with electric heaters HA and HB for heating the filters and igniting the particulates during filter regeneration. One end of each of the electric heaters HA and HB is grounded, and the other end is connected to the battery 11 via switches SWA and SWB controlled by the control circuit 100. Furthermore, filter 5
A temperature sensor ST for detecting the exhaust gas temperature is provided upstream of A and 5B, and the detected value ThG of the exhaust gas temperature of the temperature sensor ST is also input to the control circuit 100. Although not shown, the engine 1 is provided with an intake air temperature sensor that detects an intake air temperature, an intake air amount sensor that detects an intake air amount, and a water temperature sensor that detects the temperature of the engine 1 based on a water temperature. In addition, the intake air amount Ga, the intake air temperature ThA, and the water temperature ThW from these sensors are also input to the control circuit 100.

The branch part a is provided with a first control valve V1 for diverting the flow of exhaust gas from the exhaust pipe 2 upstream of the branch part a to the branch pipes 2A and 2B. A second control valve V2 for switching the connection of the pipes 2A and 2B to the exhaust pipe 2D on the downstream side of the junction b is provided. These control valves V1 and V2 are both driven by a control circuit 100. The control valves V1 and V2 are controlled by a control signal from the control circuit 100 so that the control valves V1 and V2 do not block any of the branch pipes 2A and 2B. It is positioned at a position to close one of the tubes 2A, 2B.

At the time of reproducing the filters 5A and 5B,
It is necessary to energize the electric heater HA or HB, flow regeneration gas from the downstream side of the filter 5A or filter 5B on the energized side, and discharge combustion gas from the upstream side. Therefore, in this embodiment, the branch pipe 2
A regeneration gas supply pipe 7 is provided between the junction b of A and 2B and the filters 5A and 5B, and an electric air pump 9 for supplying secondary air is provided at one end of the regeneration gas supply pipe 7. ing. A check valve V3 is provided in the regeneration gas supply pipe 7 on the secondary air discharge side of the electric air pump 9, and an opening / closing valve V5 is provided at a connection portion of the regeneration gas supply pipe 7 to the branch pipes 2A and 2B. , V6 are provided. Further, a pressure sensor 1 for detecting a pressure between the check valve V3 and the discharge port of the electric air pump 9 is provided in the regeneration gas supply pipe 7 between the discharge port of the electric air pump 9 and the check valve V3.
3 are provided. The pressure detection value PP of the pressure sensor 13 is also input to the control circuit 100.

A combustion gas discharge pipe 8 is provided between the branch portions a of the branch pipes 2A and 2B and the filters 5A and 5B, and one end of the combustion gas discharge pipe 8 is open to the atmosphere. A check valve V4 is provided near the open end of the combustion gas discharge pipe 8, and on-off valves V7 and V8 are provided at connecting portions of the combustion gas discharge pipe 8 to the branch pipes 2A and 2B, respectively. The valves V3 to V8 and the electric air pump 9 are all driven and controlled by the control circuit 100.

The driving of the valves V1 to V8 is actually performed by a diaphragm type actuator, a negative pressure switching valve, or an electric type actuator, but the driving mechanism is not particularly limited. And its description is omitted. However, in the present invention, it is necessary to switch some of the valves V1 to V8 immediately when the engine is started. Therefore, when a diaphragm type actuator or a negative pressure switching valve is used, the vehicle is controlled and driven by a negative pressure tank or the like. Sources need to be provided.

The control circuit 100 includes, for example, an interface INa for inputting an analog signal, an interface INd for inputting a digital signal, a converter A / D for converting an analog signal into a digital signal, a central processing unit CPU for performing various arithmetic processing, a random processing unit CPU, Access memory RAM, read-only memory ROM, backup memory B-RA that retains data even when the key switch of the engine is turned off
M, an output circuit OUT, and a microcomputer including a bus line 111 for connecting them, etc., will not be described in detail.

The interface INa for inputting an analog signal of the control circuit 100 includes a particulate filter 5.
A, the differential pressure signal PD of the exhaust gas on the upstream and downstream sides of 5B,
An intake air temperature signal ThA and a water temperature signal ThW of the engine 1, an engine speed signal Ne from a speed sensor (not shown), a pressure PP between the check valve V3 and a discharge port of the electric air pump 9, and the like are input. Interface I
A signal from a key switch or the like is input to Nd. The output circuit OUT of the control circuit 100 includes a control valve V
A valve abnormality lamp 12 indicating an abnormality of V1 and V2 is connected.

Next, the operation of the exhaust particulate removing device 20 of the diesel engine of the embodiment configured as described above will be described.

[At the time of collecting particulates in exhaust gas]
The control valves V1 and V2 are controlled to neutral positions, and the check valves V3 and V4 and the on-off valves V5 to V8 are closed. FIG. 1 shows this state, and the diesel engine 1
Exhaust gas discharged from the filter flows into both of the branch pipes 2A and 2B, particulates are removed by the filters 5A and 5B, and is discharged to the atmosphere via the muffler 6.

[When Regenerating Filter] Filters 5A and 5B
When the trapped amount of the particulates in the filter exceeds a predetermined value and the differential pressure detection values on the upstream and downstream sides of the filters 5A and 5B of the differential pressure sensor 10 exceed the reference values, the filter regeneration processing is executed from the filter 5A. You. At the time of regeneration of the filter 5A, the control valves V1 and V2 close the inlet side and the outlet side of the branch pipe 2A, and the check valves V3 and V4 and the on-off valves V5 and V7 are opened. The secondary air from the air pump 9 is supplied to the regeneration gas supply pipe 7.
Is supplied to the filter 5A, the heater HA is energized, and the particulates in the filter 5A burn,
The combustion gas is discharged into the atmosphere through a combustion gas discharge pipe 8. During regeneration of the filter 5B, the control valves V1 and V2 close the inlet and outlet sides of the branch pipe 2B, and the check valves V3 and V4
Remain open, the on-off valves V5 and V7 close, and the on-off valve V
6, V8 is opened. The secondary air from the air pump 9 is supplied to the filter 5B through the regeneration gas supply pipe 7, the heater HB is energized to burn the particulates in the filter 5B, and the combustion gas passes through the combustion gas discharge pipe 8. Released into the atmosphere.

FIG. 2 shows the operation of the control circuit 100 for detecting an abnormality of the control valves V1 and V2 during the filter regeneration process in the embodiment shown in FIG. This reproduction processing is actually executed in an interrupt form at predetermined time intervals, but here, in order to briefly show the overall flow of the processing,
The reproduction process is shown as a continuous flow from the start to the end, and an interval is provided in the middle of the process to indicate that the process is performed at predetermined time intervals. All subsequent flowcharts will be described in this form.

In step 201, the differential pressure PD is detected, and in step 202, it is determined whether or not it is a regeneration time. The determination of the regeneration timing is made based on whether or not the output value PD of the differential pressure sensor 10 is equal to or greater than the determination value. If it is not the regeneration time, after a predetermined interval (indicated by □), the differential pressure PD is detected again in step 201, and the process of determining in step 202 whether or not it is the regeneration time is repeated. On the other hand, when it is determined in step 202 that it is the reproduction time, the process proceeds to step 203.

In step 203, a regeneration process of the filter 5A is executed. At the time of regeneration processing of the filter 5A, the control valve V
1 and V2 block the inlet and outlet sides of the branch pipe 2A, and the check valves V3 and V4 and the on-off valves V5 and V7 are opened. In this state, the secondary air from the electric air pump 9 is supplied to the filter 5A through the regeneration gas supply pipe 7, and the heater HA is energized. The heater HA is energized to ignite and burn the particulates in the filter 5A, and the combustion gas is discharged into the atmosphere through the combustion gas discharge pipe 8. At this time, the exhaust gas flows to the filter 5B, and the filter 5B continues collecting particulates.

During the regeneration processing of the filter 5A as described above, the discharge pressure PP of the electric air pump 9 is detected. In step 204, the discharge pressure PP of the electric air pump 9 is set to the minimum discharge pressure Pmin and the maximum discharge pressure Pmin in the normal regeneration processing. It is determined whether or not the pressure is between the discharge pressures Pmax. This is the control valve V
1, V2 determines whether or not the branch pipe 2A is normally closed. As shown in FIG. 3, when both the control valves V1 and V2 normally close the branch pipe 2A, the discharge pressure PP becomes P from the start of regeneration of the filter 5A to the end of regeneration.
min ≦ PP ≦ Pmax. On the other hand, if PP <Pmin, the control valve V2 does not normally close the branch pipe 2A, and secondary air flows to the exhaust pipe 2D without being supplied to the filter 5A, and the discharge pressure PP decreases. Possible state, P
When P ≧ Pmax, the control valve V1 does not normally close the branch pipe 2A, and an abnormal state in which the exhaust gas flows into the branch pipe 2A and the discharge pressure PP increases may be considered.

First, when the control valves V1 and V2 are normally
A case where A is closed will be described. In this case, it is determined in step 205 whether or not the valve abnormality flag VAEF is "1", and when the control valves V1 and V2 are normal, VAEF = "
Since the value is "0", the process proceeds to step 206 to determine whether or not the reproduction is completed, and thereafter, the processing from step 203 to step 206 is repeated at predetermined intervals until the reproduction is completed. VAEF is "
It is set to "0" and becomes "1" when any of the control valves V1 and V2 does not normally close the branch pipe 2A.

Next, a case where one of the control valves V1 and V2 does not normally close the branch pipe 2A will be described.
In this case, in step 204, PP <Pmin or PP
.Gtoreq.Pmax, and the routine proceeds to step 207. Step 20
In step 7, the valve abnormality lamp 12 is turned on and off, and in step 208, the valve abnormality flag VAEF is set to "1". Then, it is determined in step 206 whether or not the reproduction has been completed, and the process returns to step 203 after a predetermined interval. The control valve V
Once an abnormality occurs in which one of V1 and V2 does not normally close the branch pipe 2A, the valve abnormality flag VAEF is set to "1" in step 208, and then Pmin≤PP≤Pmax in step 204. However, since VAEF = “1” in step 205, step 2
In step 07, the blinking of the valve abnormality lamp 12 is continued.

When the regeneration of the filter 5A is completed in this way, the process proceeds from step 206 to step 209, where the flow path of the exhaust gas is switched. That is, the control valves V1, V2
Close the inlet and outlet sides of the branch pipe 2B with the check valve V
While the valves 3 and V4 are open, the valves V5 and V7 are closed, and the valves V6 and V8 are opened. Then, in step 210, the secondary air from the electric air pump 9 is supplied to the filter 5B through the regeneration gas supply pipe 7, and the heater HB is energized to burn the particulates in the filter 5B. It is discharged into the atmosphere through a pipe 8. At this time, the exhaust gas flows to the filter 5A, and the filter 5A is collecting particulates.

During the regeneration processing of the filter 5B as described above, the discharge pressure PP of the electric air pump 9 is detected, and in step 211, the discharge pressure PP of the electric air pump 9 is regenerated in the same manner as in the case of the filter 5A. It is determined whether the pressure is between the minimum discharge pressure Pmin and the maximum discharge pressure Pmax during the processing. If the control valves V1 and V2 normally close the branch pipe 2B, it is determined in step 212 whether the valve abnormality flag VBEF is "1". If the control valves V1 and V2 are normal, the process proceeds to step 213. It is determined whether or not the reproduction has ended, and thereafter, the processing of steps 211 to 213 is repeated at predetermined intervals until the reproduction ends.

If one of the control valves V1 and V2 does not normally close the branch pipe 2A, at step 211
<Pmin or PP ≧ Pmax, and step 214
Proceed to. In step 214, the valve abnormality lamp 12 is turned on and off, and in step 215, the valve abnormality flag VBEF is set to "
1 ". Then, it is determined in step 213 whether or not the reproduction has been completed.
Return to During regeneration of the filter 5B, if an abnormality occurs in which one of the control valves V1 and V2 does not normally close the branch pipe 2A once, Pmin ≦ P in step 211 during regeneration.
Even if P ≦ Pmax, the routine proceeds to 214, where the valve abnormality lamp 12 continues blinking.

As described above, in the exhaust gas particulate removing apparatus for a diesel engine according to the present invention, since an abnormality of the exhaust control valve can be detected, the exhaust gas flows into the filter being regenerated and the secondary air flow is reduced. It is possible to reduce the risk that unburned residue due to shortage of the secondary air will occur due to obstruction. FIG. 4 shows a procedure of another embodiment of the control of the control device 100 in the exhaust particulate removal device for a diesel engine according to the present invention. When the processing of FIG. 4 is executed, in the exhaust particulate removal apparatus 20 of the diesel engine of FIG. 1, the pressure sensors SP1 and SP2 are provided on the regeneration gas supply pipe 7 side and the combustion gas discharge pipe 8 side of the filter 5A, respectively. It is necessary to provide pressure sensors SP3 and SP4 on the regeneration gas supply pipe 7 side and the combustion gas discharge pipe 8 side of the filter 5B, respectively. In this case, the detection values of the pressure sensors SP1 to SP4 are respectively P
1 to P4.

In this embodiment, the differential pressure PD is detected in step 401, and it is determined in step 402 whether or not it is the regeneration time. The determination of the regeneration timing is based on the differential pressure sensor 10
Is determined based on whether or not the output value PD is equal to or greater than the determination value. If it is not the reproduction time, after a predetermined interval, step 401 is performed again.
, The process of determining whether or not it is the regeneration time in Step 402 is repeated. Step 4
When it is determined in step 02 that it is the reproduction time, step 403 is executed.
Proceed to.

In step 403, a regeneration process of the filter 5A is executed. At the time of regeneration processing of the filter 5A, the control valve V
1 and V2 block the inlet and outlet sides of the branch pipe 2A, and the check valves V3 and V4 and the on-off valves V5 and V7 are opened. In this state, the secondary air from the electric air pump 9 is supplied to the filter 5A through the regeneration gas supply pipe 7, and the heater HA is energized. The heater HA is energized to ignite and burn the particulates in the filter 5A, and the combustion gas is discharged into the atmosphere through the combustion gas discharge pipe 8. At this time, the exhaust gas flows to the filter 5B, and the filter 5B continues collecting particulates.

In step 404, it is determined whether or not one minute before the end of the regeneration processing of the filter 5A. If one minute before the end of the reproduction processing of the filter 5A, the process returns to step 403 after a predetermined interval, and repeats the determination of step 404. If it is determined in step 404 that the current time is one minute before the end of the regeneration of the filter 5A, the process proceeds to step 405, where the differential pressure PA = P1-P2 between the upstream and downstream of the filter 5A is detected. It is determined in step 406 whether or not the pressure difference is larger than the differential pressure PAmax. If PA ≦ PAmax, the routine proceeds to step 407, where the differential pressure PA detected in step 405 is the minimum allowable differential pressure PAmi at the end of the regeneration.
Determine if it is less than n.

If the regeneration of the filter 5A is performed normally and the control valves V1 and V2 are operating normally, step 40
6 is NO, step 407 is NO and step 41
Proceed to 2. On the other hand, when the control valve V1 is not operating normally, the exhaust gas flows into the regeneration downstream side of the filter 5A, so that the pressure P2 increases and PA <PAmin. Further, when the control valve V2 is not operating normally, the secondary air flows out to the exhaust pipe 2D side, so that the pressure P1 decreases and P
A <PAmin. In such a case, step 406
Is NO, and step 407 is YES, and the process proceeds to step 408. At step 408, the abnormality lamp 12 of the control valve is turned on and off, and at step 409, processing for increasing the amount of secondary air at the time of the next regeneration of the filter 5A is performed, and the routine proceeds to step 412. In the process of step 409, regardless of which of the control valves V1 and V2 is abnormal, the current secondary air amount is too small and the regeneration process is not performed normally, so the secondary air amount is increased at the next regeneration. It is for.

Further, when there is much unburned particulate matter in the filter 5A during the regeneration processing of the filter 5A,
The differential pressure PA upstream and downstream of the filter 5A becomes larger than PAmax. In such a case, in step 406, YE
In S, the routine proceeds to step 410, where an unburned abnormal lamp (not shown in FIG. 1 but provided in the same manner as the valve abnormal lamp 12) is flickered. Then, in step 411, a process of increasing the power of the heater HA and the amount of secondary air at the time of the next regeneration of the filter 5A is performed, and the process proceeds to step 412.

In step 412, it is determined whether or not one minute has elapsed since it was determined in step 404 that the current time was one minute before the reproduction processing, and it is determined whether or not the reproduction processing has ended. Step 412 is executed at predetermined intervals until the answer is YES. Then, after YES in step 412, the flow path of the exhaust gas is switched in step 413. That is, the control valves V1 and V2 close the inlet and outlet sides of the branch pipe 2B, and the check valves V3 and V2
With the valve 4 open, the valves V5 and V7 are closed, and the valve V
6, V8 is opened. Then, the secondary air from the electric air pump 9 is supplied to the filter 5B through the regeneration gas supply pipe 7, the heater HB is energized to burn the particulates in the filter 5B, and the combustion gas is discharged through the combustion gas discharge pipe 8. Release to atmosphere. At this time, the exhaust gas flows to the filter 5A, and the filter 5A is collecting particulates.

The processing in steps 414 to 424 is the same as the processing of the filter 5A in steps 403 to 413 described above executed for the filter 5B. In step 414, the reproduction processing of the filter 5B is executed. One minute before the end of regeneration of the filter 5B, the differential pressure PB = P3-P4 upstream and downstream of the filter 5B is detected in step 416, and the detected differential pressure PB is larger than the maximum allowable differential pressure PBmax at the end of regeneration. It is determined in step 417 whether or not this is the case. If PB ≦ PBmax, the routine proceeds to step 418, where the differential pressure PB detected in step 416 is the minimum allowable differential pressure PBmi at the end of regeneration.
Determine if it is less than n.

If the regeneration of the filter 5B is performed normally and the control valves V1 and V2 are operating normally, step 41
7 is NO, step 417 is NO and step 41
Proceed to 2. If the control valve V1 is not operating normally, or if the control valve V2 is not operating normally, PB <P
Bmin, NO in step 417, step 418
Is YES, and the routine proceeds to step 419. Step 41
In step 9, the abnormality lamp 12 of the control valve blinks, and
At 20, a process of increasing the amount of secondary air at the time of the next regeneration of the filter 5 </ b> B is performed, and the process proceeds to step 423.

During the reproduction process of the filter 5B, the filter 5B
PB> P when there is a lot of unburned particulates
Since Bmax is reached, the answer is YES in step 417, and the process proceeds to step 421, in which an unburned abnormal lamp (not shown in FIG. 1) blinks. Then, in step 422, a process of increasing the electric power of the heater HB and the amount of secondary air at the time of the next regeneration of the filter 5 </ b> B is performed, and the process proceeds to step 423.

In step 423, it is determined whether or not one minute has elapsed since the determination of one minute before the regeneration processing of the filter 5B in step 415, and the regeneration processing has ended.
Step 423 is executed at predetermined intervals until YES is reached. Then, after YES in step 423, the flow path of the exhaust gas is switched. That is, the control valves V1 and V2 are set to neutral 1, the check valves V3 and V4, and the on-off valves V5 to V8 are all closed, and the drive of the electric air pump 9 is stopped. This state is a state where the filters 5A and 5B shown in FIG. 1 are simultaneously collected.

In the embodiment described above, it is possible to detect an abnormality in the control valve and the unburned residue at the time of regeneration of the filter and to notify the occupant, and when it is detected, appropriate processing may be performed at the next regeneration. it can. The exhaust particulate removing device 20 of the diesel engine in the embodiment described above simultaneously collects particulates in the exhaust gas using the filters 5A and 5B, and converts the secondary air during the regeneration time in the direction opposite to the flow of the exhaust gas. Of the simultaneous collection and reverse flow alternate regeneration type in which the filters 5A and 5B are alternately regenerated by flowing from the filter, but the present invention is limited to this simultaneous collection and reverse flow alternate regeneration type exhaust particulate removal device of a diesel engine. Not something. For example, as shown in FIG. 5, the particulates in the exhaust gas are simultaneously collected by using the filters 5A and 5B, and the secondary air is caused to flow from the same direction as the flow of the exhaust gas at the time of the regeneration so that the filters 5A and 5B are removed. Simultaneous collection of alternately regenerating, forward flow alternating regenerating type diesel engine exhaust particulate removal device 30,
The present invention can be applied to a diesel engine exhaust particulate removing device 40 of a type in which a filter is provided in only one of the branch pipes 2A and 2B as shown in FIG.

In the diesel engine exhaust particulate removing devices 30 and 40 shown in FIGS. 5 and 6, the same components as those of the diesel engine exhaust particulate removing device 20 are denoted by the same reference numerals. Therefore, description of the configuration is omitted. FIG. 7 shows a control valve V in the exhaust particulate removing devices 20 and 30 of the diesel engine shown in FIGS.
1 shows an example of the configuration of FIG. When the opening and closing operation of the control valve V1 is performed by a diaphragm device using a negative pressure and a spring force, that is, a negative pressure is applied to the diaphragm to suck the rod, and when no negative pressure is applied, the rod is protruded by the force of the spring. When the operation is performed by the diaphragm device, the suction force of the rod due to the negative pressure is smaller than the projection force of the rod due to the spring. Therefore, the diaphragm 71 and the spring 7 for urging the diaphragm 71
2. When the diaphragm device 70 having the rod 73 protruding from the diaphragm 71 is used for driving the control valve V1, the arrangement of the branch pipes 2A and 2B and the diaphragm device 70 is as shown in FIG. . However, illustration of the regeneration gas supply pipe 7 or the combustion gas discharge pipe 8 is omitted.

That is, the branch pipe 2B branches perpendicularly from the branch pipe 2A, and the control valve V1 provided at the branch part a is connected to the branch pipe 2A as shown in FIG.
As shown in FIG. 7A, in a state where the diaphragm 71 is sucked by the negative pressure, the control valve V1 closes the branch pipe 2A, and in a state where the diaphragm 71 is urged by the spring force as shown in FIG. The control valve V1 is configured to close the branch pipe 2B. With this configuration, in the state of FIG. 7A, the control valve V1 urges the branch pipe 2A in the valve closing direction by the pressure of the exhaust gas, so that the weakness of the valve closing force of the branch pipe 2A due to the negative pressure is reduced. I can make up for it.

FIG. 8 shows another embodiment of the configuration of the control valve V1 in the exhaust particulate removing devices 20, 30 of the diesel engine shown in FIGS. As described above, when the opening / closing operation of the control valve V1 is performed by the diaphragm 71, the spring 72 for urging the diaphragm 71, and the diaphragm device 70 including the rod 73 protruding from the diaphragm 71, the rod 73 by the negative pressure is used. The suction force is smaller than the projection force of the rod 73 by the spring 72.
Therefore, as shown in FIGS.
The branch pipe 2A that performs regeneration first is closed by the biasing force of the above, and the branch pipe 2B that performs regeneration later is configured to be closed by the force of the negative pressure. However, illustration of the regeneration gas supply pipe 7 or the combustion gas discharge pipe 8 is omitted.

In this case, the amount of exhaust gas leaking from the control valve V1 to the filter being regenerated is larger due to the negative pressure shown in FIG. 8B. However, in the exhaust particulate removal device for a diesel engine that performs simultaneous collection and alternate regeneration, the amount of particulates collected on the filter 5A side that performs regeneration first is small, so that the control valve V1 is regenerated by the spring force during regeneration of the filter 5A. When the branch pipe 2A is reliably closed, 2
The next air can be flowed according to the setting, and good regeneration can be performed.
On the other hand, the filter 5B for performing reproduction later is the filter 5B.
A large amount of particulates is collected because the collection is performed during regeneration of A. Even if the amount of secondary air decreases due to a small amount of exhaust gas flowing from the control valve V1 during regeneration, unburned residue is generated. Hard to do.

FIG. 9 shows an embodiment in which the exhaust pipe 2 is curved on the upstream side of the branch portion a of the branch pipes 2A and 2B in the exhaust particulate removal apparatus for a diesel engine that performs simultaneous collection. . In such a case, as shown in FIG. 9C, a large amount of exhaust gas flowing through the exhaust pipe 2 flows into the branch pipe 2B outside the curved portion of the exhaust pipe 2 and is collected by the filter 5B during simultaneous collection. The amount of particulates increases. Therefore, as shown in FIGS. 9A and 9B, the branch pipe 2A,
A honeycomb-shaped rectifying device 90 having a large number of partition walls is provided on the upstream side of the branch portion a of 2B. Since a number of rectangular parallelepiped passages (cells) surrounded by partition walls are provided in parallel inside the rectification device 90, the flow of the exhaust gas is corrected by passing through the cells, and the rectification is performed. Device 90
When you exit, it becomes a parallel flow. As a result, filter 5
The collection amount and collection distribution of A and 5B can be made equal.

[0050]

As described above, according to the exhaust particulate removing apparatus for a diesel engine according to the present invention, the exhaust gas is prevented from flowing into the filter being regenerated by using the exhaust cutoff valve during the regeneration processing of the filter. In a conventional diesel engine exhaust particulate removal apparatus, there is an effect that an abnormality of the exhaust gas cutoff valve can be detected during regeneration of the filter.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of an exhaust particulate removal apparatus of a simultaneous collection and backflow alternating regeneration dual filter type according to the present invention.

FIG. 2 is a flowchart showing one embodiment of a filter regeneration processing procedure of the control circuit of FIG. 1;

FIG. 3 is a diagram showing a discharge pressure of an electric air pump at the time of filter regeneration.

FIG. 4 is a flowchart showing another embodiment of the filter regeneration processing procedure of the control circuit of FIG. 1;

FIG. 5 is a diagram showing a schematic configuration of an embodiment of an exhaust particulate removing apparatus of a simultaneous collection and a forward flow alternating regeneration dual filter type according to the present invention.

FIG. 6 is a diagram showing a schematic configuration of an embodiment of an exhaust particulate removal apparatus of a backflow regeneration single filter type according to the present invention.

FIGS. 7A and 7B are explanatory diagrams showing a configuration and a switching operation of an embodiment when a diaphragm type actuator is used for driving a first control valve.

FIGS. 8 (a) and (b) are explanatory diagrams showing a configuration and a switching operation of another embodiment when a diaphragm type actuator is used for driving a first control valve.

FIG. 9 (a) is a partial configuration diagram showing the configuration of a diesel engine according to the present invention in which a rectifier is used in the exhaust particulate removal device, and FIG. 9 (b) shows the configuration of the rectifier alone used in (a). FIG. 3C is an explanatory view showing a flow of exhaust gas in a conventional dual filter type diesel engine exhaust particulate removing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Diesel engine 2 ... Exhaust pipe 2A, 2B ... Branch pipe 5A, 5B ... Filter 7 ... Regeneration gas supply pipe 8 ... Combustion gas discharge pipe 9 ... Air pump 10 ... Differential pressure sensor 12 ... Valve abnormality lamp 70 ... Diaphragm actuator 71 ... diaphragm 72 ... spring 73 ... rod 90 ... rectifying device 100 ... control circuit a ... branch part b ... convergence part HA, HB ... electric heater V1 ... first control valve V2 ... second control valve V3, V4 ... check Valves V5 to V8: On-off valve

Continuation of the front page Examiner Ryuichi Komatsu (56) References JP-A-6-330729 (JP, A) JP-A-6-173650 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) ) F01N 3/02 301-341

Claims (1)

(57) [Claims] 1. A state in which particulates in exhaust gas are collected by a filter provided in an exhaust passage of an engine, and the exhaust gas is blocked by an exhaust control valve during regeneration of the filter. In a diesel engine exhaust particulate removing device that ignites particulates collected by a filter and supplies regeneration gas from regeneration gas supply means, the discharge pressure of the regeneration gas supply means or the exhaust control An exhaust particulate removing device for a diesel engine, comprising: means for detecting a pressure on the downstream side of the valve; and means for determining abnormality of the exhaust control valve based on the detected pressure value.