JP3210710B2 - Exhaust gas purification device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for an internal combustion engine, and more particularly, to regeneration of a filter in an apparatus for collecting and removing particulates contained in exhaust gas of a diesel engine by a filter provided in an exhaust passage. and an exhaust purification device engine during filter regeneration can be performed normally be stopped operation.

[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.

FIG. 6 shows a conventional exhaust gas purifying apparatus 10 for an internal combustion engine.
1 shows a general configuration of a conventional exhaust gas purifying device 10 of a reverse flow type in which a regeneration gas flows from a direction opposite to a direction in which exhaust gas flows to regenerate a filter for collecting particulates. Things. In the figure, 1 is a diesel engine, 2 is an exhaust gas passage, 3 is an exhaust gas passage 2
, A filter housing, a sealing material, a sealing material, a particulate filter for trapping particulates in exhaust gas contained in the casing 3, a secondary air supply passage 6, 7 is a combustion gas discharge passage, 8 is an exhaust bypass passage that bypasses the particulate filter 5, 9 is an air pump that supplies secondary air,
H is an electric heater, V1 is a switching valve for switching between the exhaust passage 2 and the exhaust bypass passage 8, V2 is an outlet switching valve provided at the outlet of the exhaust bypass passage 8, V3 is an opening / closing valve for the combustion gas discharge passage 7, and V4 is 3 shows an on-off valve of a secondary air supply passage 6.

At the time of collecting particulates in normal exhaust gas, each of the valves V1 to V4 is located at a position indicated by a broken line, and the exhaust gas discharged from the diesel engine 1 is subjected to a particulate filter 5 incorporated in a casing 3 by a particulate filter 5. The curate is removed and released to the atmosphere via a muffler (not shown). Exhaust gas purification apparatus 10 configured as above
Then, if the amount of the particulates collected inside the particulate filter 5 increases with the use of the particulate filter 5, the air permeability gradually decreases, and the engine performance decreases, so that the end of the particulate filter 5 It is necessary to regenerate a filter that burns the particulates by supplying a regeneration gas, for example, secondary air, to the particulate filter 5 while energizing the electric heater H provided.

Generally, a conventional exhaust gas purifying apparatus 1 for an internal combustion engine is used.
In the case of 0, when the gas permeability of the particulate filter 5 is lost and the pressure of the exhaust gas on the upstream side of the filter 5 becomes larger than the pressure on the downstream side by more than a predetermined value (when the pressure loss becomes more than the predetermined value) ) Is detected by the pressure sensor, and a particulate regeneration process is performed. During this regeneration process, each of the valves V1 to V4 switches to the position indicated by the solid line. In this state, the exhaust gas from the diesel engine 1 is discharged into the air through the exhaust bypass passage 8. At this time, the heater H is energized and the air pump 9
The secondary air is supplied, and the particulates collected by the particulate filter 5 are burned. Then, the combustion gas is released from the combustion gas discharge passage 7 into the air.
The power consumption of the electric heater H is about 1600 W.

However, in the exhaust gas purifying apparatus 10 configured as described above, if the engine is stopped while the electric heater H is energized, the energization of the electric heater H and the supply of the secondary air are stopped. Particulates on the way disappear after burning only around the electric heater H. Then, when the operation of the engine is restarted next time, since there is no particulate matter around the electric heater H as a fire source, it becomes difficult to regenerate the particulate filter 5.

Therefore, a method of supplying secondary air after stopping the engine and simultaneously supplying electricity to the electric heater H to heat and regenerate the particulate filter (Japanese Patent Laid-Open No. 58-140412), a method of regenerating the particulate filter, When the ignition switch is turned off during the operation, the regeneration should not be terminated in the middle like a device that continues the operation of the engine until the regeneration is completed (Japanese Utility Model Application Laid-Open No. 62-128108 or Japanese Utility Model Application Laid-open No. 3-43519). Those that control the engine have been proposed.

[0008]

SUMMARY OF THE INVENTION However, Japanese Patent Application Laid-Open
In the method described in Japanese Patent Application Laid-Open No. 58-140412, there is a risk that the battery will run out. In the device described in Japanese Utility Model Application Laid-Open No. 62-128108 or Japanese Utility Model Application Laid-Open No. , The fuel efficiency is greatly deteriorated, and there is a risk that the diesel engine that has been left idle may generate noise.
Also, when a burner or the like is used as a heating means, it is necessary to operate a fuel pump for supplying fuel to the burner, and energy for the operation is required, and in this case, the battery runs out. There was fear.

Therefore, the present invention solves the above-mentioned problems of the conventional exhaust gas purifying apparatus for an internal combustion engine, so that even if the ignition switch of the engine is turned off at the time of regeneration of the particulate filter, no load is imposed on the battery. It is another object of the present invention to provide an exhaust gas purifying apparatus for an internal combustion engine capable of completing the regeneration of a particulate filter in a regeneration state without causing a problem of fuel consumption and noise.

[0010]

Means for Solving the Problems] The configuration of an exhaust purification system of an internal combustion engine of the present invention to achieve the above object shown in FIG. FIG.
As shown in FIG. 1, the present invention captures particulates in exhaust gas by a filter 5 provided in an exhaust gas passage of the internal combustion engine 1, and heats the filter H when it is necessary to regenerate the filter.
Performing heating by ignite particulates in the filter, in the exhaust purification apparatus to regenerate the filter 5 by burning it by supplying a regeneration gas by regeneration gas supply means 9 at the same time, the fill
Regeneration state detecting means for detecting the regeneration state of the filter 5
A, an operating state detecting means B of the heating means for detecting an operating state of the heating means H, an ignition switch state detecting means C for detecting an on / off state of an ignition switch IG of the internal combustion engine 1, and an ignition switch IG turned on. When the heating means H is in the operating state when the state is turned off, the operation of the internal combustion engine is maintained.
Both the operation control unit D of the internal combustion engine the operation of the heating means H to stop the operation of the internal combustion engine 1 to be turned off, when the ignition switch IG is turned off from the on state, the filter 5 is reproduced state At one time, a regeneration gas supply operation means E for maintaining the operation of the regeneration gas supply means 9 until the regeneration state ends is provided.

[0011]

According to the exhaust gas purifying apparatus for an internal combustion engine of the present invention, when the ignition switch is turned off from the on state when the particulate filter is in the regeneration state and the heating means is in the operating state, the heating means The operation of the internal combustion engine is maintained until the operation of is turned off, and at the same time, the operation of the regeneration gas supply means is maintained until the regeneration state of the particulate filter ends.

[0012]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 2 is an overall configuration diagram of an exhaust gas purifying apparatus 20 for an internal combustion engine according to an embodiment of the present invention, which is provided with an electric heater H and a particulate filter 5 for trapping particulates in exhaust gas. The same components as those of the conventional exhaust gas purification apparatus 10 for an internal combustion engine shown in FIG. Therefore, in FIG.
Is a casing for accommodating the particulate filter 5 provided in a part of the exhaust gas passage 2, 4 is a sealing material, 6 is a secondary air supply passage, 7 is a combustion gas discharge passage, 8
Is an exhaust bypass passage that bypasses the particulate filter 5, 9 is an electric air pump that supplies secondary air,
1 is a switching valve for switching between the exhaust passage 2 and the exhaust bypass passage 8, V2 is an outlet switching valve provided at the outlet of the exhaust bypass passage 8, V3 is an on-off valve for the combustion gas discharge passage 7, and V4 is a secondary air supply passage. 6 shows the on-off valve 6. The components newly added to FIG. 2 include a battery 11, a parking brake lock mechanism 12, a control circuit 100, a backup switch BS, and a heater relay H for energizing the electric heater H.
R, ignition switch I connected to battery 11
G, a pressure sensor SP1 provided in the passage 2 on the exhaust gas inflow side of the particulate filter 5, and a pressure sensor SP2 provided in the passage 2 on the exhaust gas outflow side of the particulate filter 5.

The particulate filter 5 is a honeycomb filter having a honeycomb-shaped partition wall made of a porous material. The particulate filter 5 is generally cylindrical and has a large number of rectangular parallelepiped passages surrounded by partition walls. The adjacent passage is alternately plugged with a closing member made of ceramic on the exhaust gas inflow side and the exhaust gas outflow side to form a closed passage.

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, The microcomputer includes a microcomputer including an access memory RAM, a read-only memory ROM, an output circuit OUT, and a bus line 111 for connecting them, but a detailed description of the configuration is omitted. The interface INa for inputting an analog signal of the control circuit 100 includes pressure detection signals from pressure sensors SP1 and SP2 for detecting the pressure of exhaust gas on the upstream and downstream sides of the exhaust gas path of the particulate filter 5, and rotation (not shown). An engine speed signal Ne or the like from a number sensor is input, and a signal or the like from an ignition switch IG is input to a digital signal input interface INd.

At the time of collecting particulates in the normal exhaust gas, the valves V1 to V4 are controlled to the positions indicated by broken lines, and the exhaust gas discharged from the diesel engine 1 receives The particulates are removed by 5 and released into the atmosphere via a muffler (not shown). On the other hand, the pressure on the exhaust gas inflow side (upstream side) of the particulate filter 5 becomes larger than the pressure on the exhaust gas outflow side (downstream side) beyond a predetermined value, and the pressure loss becomes higher than the predetermined value. When detected by the pressure sensors SP1, SP2, the control circuit 100
As a result, the valves V1 to V4 are switched from the positions indicated by broken lines to the positions indicated by solid lines, and the regeneration operation of the particulate filter 5 is performed. When the particulate filter 5 is switched to the regenerating operation, the control circuit 100 controls on / off of the heater relay HR and control of the flow rate of the secondary air from the electric air pump 9 together.

FIG. 3 is a routine showing control during reproduction of the particulate filter 5 by the control circuit 100.
It is executed every predetermined time. In step 301, it is first determined whether or not the particulate filter 5 is being regenerated. When the particulate filter 5 is not being regenerated, it is determined in step 302 whether or not the particulate filter 5 has reached the regeneration timing based on the aforementioned pressure loss value. If it is not the filter regeneration time (NO), this routine ends.

On the other hand, if it is determined in step 302 that the filter regeneration time has been reached (YES), the flow proceeds to step 303, in which the energization time of the heater H and the filter regeneration time are set. The energization, the switching of the switching valves V1 and V2, the opening of the on-off valves V3 and V4, the operation of the electric air pump 9, and the turning on of the backup switch BS are performed, and the regeneration of the particulate filter 5 is started. During the subsequent reproduction of the particulate filter 5, YES is obtained in step 301, so that steps 302 to 304
Is omitted and the process proceeds to step 305.

In step 305, it is determined whether or not the ignition switch IG is turned off during the reproduction of the particulate filter 5. First, during reproduction of the particulate filter 5, the ignition switch I
A case where G is not turned off will be described, and then a case where G is turned off will be described. (1) If the ignition switch is on throughout the filter regeneration period In this case, it is determined in step 306 whether or not the energization time to the heater H has ended. If not (NO), this routine ends. When the energization time to the heater H has ended (YES), the energization to the heater H is stopped in step 307. Subsequently, in step 308, it is determined whether or not the reproduction time of the particulate filter 5 has expired. If the reproduction time has not ended (NO), this routine ends, and if it has ended (YES), the flow proceeds to step 309.

At step 309, switching of the switching valves V1 and V2 (switching from the solid line position to the broken line position in FIG. 2) is performed, and the on-off valves V3 and V4 are closed.
Is stopped and the backup switch BS is turned off, and this routine ends. As a result, the exhaust gas from the internal combustion engine 1 passes through the particulate filter 5 again, and the supply of the secondary air is stopped.

(2) When the ignition switch is turned off during the filter regeneration period In this case, in step 310, an instruction to continue the operation of the internal combustion engine 1, an increase in the idle speed, and an instruction to lock the parking brake are issued. The operation continuation instruction of the internal combustion engine 1 is performed, for example, by continuously supplying fuel to the fuel injection pump. In addition, the fact that the ignition switch IG is turned off means that the vehicle is in a stopped state, so that the idling speed is increased to supplement the charging of the battery 11, and a parking brake locking instruction is issued.
This is to prevent the vehicle with the automatic transmission from moving forward even if the ignition switch IG is turned off at the drive position or the like.

In step 311, it is determined whether or not the energizing time to the heater H has ended. If not (NO), this routine ends, and if the energizing time to the heater H has ended (YES). In step 312, the power supply to the heater H is stopped in step 312, an operation stop instruction of the internal combustion engine 1 is issued, and the engine stops. Subsequently, in step 313, it is determined whether or not the reproduction time of the particulate filter 5 has expired. If the reproduction time has not ended (NO), this routine ends. If it has ended (YES), the flow proceeds to step 314.

In step 314, switching of the switching valves V1 and V2 (switching from the solid line position to the broken line position in FIG. 2) is performed, the on-off valves V3 and V4 are closed, and the electric air pump 9 is turned on.
, The backup switch BS is turned off, and the parking brake is unlocked, and this routine ends. As a result, the exhaust gas from the internal combustion engine 1 can pass through the particulate filter 5 again, and
The supply of the next air is stopped.

FIG. 4 shows the operation of each part of the exhaust gas purifying apparatus for an internal combustion engine shown in FIG. 2 in the case of the above (2). In the course of the ignition switch IG is the internal combustion engine 1 in the on state is in operation, the regeneration of the particulate filter 5 is started at time t _1, the heater H is turned on, the backup switch BS is turned on, electric The air pump 9 is operated, and the on-off valves V3 and V4 are opened. Thereafter, even if the heater H is the ignition switch IG is turned off at time t ₂ when in operation, the control circuit 10
By 0, the on state of the heater H is continued, the backup switch BS is kept on, the electric air pump 9 is operated, and the on-off valves V3 and V4 remain unchanged from the open state.

At time t ₃ , when the heater H is turned off and the heater H is turned off, only the internal combustion engine 1 is stopped, the backup switch BS is kept on, the electric air pump 9 is operated, and the on-off valve is turned on. V3 and V4 remain unchanged from valve opening. Thereafter, when the reproduction time is completed at time t _4, the backup switch BS is turned off, the electric air pump 9 is stopped operating, opening and closing valves V3, V4 is closed.

As described above, according to the present invention, even if the ignition switch IG is turned off while the heater H is energized, the operation of the internal combustion engine 1 is continued. Further, since the operation of the internal combustion engine 1 is stopped when the energization of the heater H is completed, the problems of fuel consumption deterioration and noise can be minimized. The embodiment described above is an example of an exhaust gas purification device for an internal combustion engine in which one particulate filter 5 is provided in the exhaust passage of the internal combustion engine. And a dual filter type internal combustion engine exhaust purification device 30 provided with two particulate filters 5A and 5B. The exhaust gas purifying apparatus 30 of the internal combustion engine shown in FIG. 5 is of a normal washing type in which regeneration of the particulate filters 5A and 5B is performed by flowing regeneration gas from the same direction as the exhaust gas flows. The constituent members are the same as those in the embodiment of FIG. 2 except for the particulate filters 5A and 5B, so that the same reference numerals are given and the description thereof will be omitted. In the exhaust purification device 30 for a dual-type internal combustion engine, the exhaust passage 2 is divided into the branch passages 2A and 2A.
B, and switching valves V5 and V
6 are provided. Further, in the branch passages 2A and 2B, there are provided particulate filters 5A and 5B, respectively.
Electric heaters HA and HB for the regeneration are provided.

In such a dual-type exhaust gas purifying apparatus 30 for an internal combustion engine, at the time of collecting particulates in the normal exhaust gas, each of the valves V1 to V6 is at a position shown by a broken line.
Exhaust gas discharged from the diesel engine 1 is supplied to a particulate filter 5 built in the branch passages 2A and 2B.
The particulates are removed by A and 5B and released into the atmosphere. The switching valves V5 and V6 may be controlled so as to close one of the branch passages 2A and 2B and open the other during particulate collection.

During the regenerating process of the exhaust gas purifying apparatus 30 configured as described above, the valves V1 to V6 are switched to the positions indicated by the solid lines. In this state, the exhaust gas from the diesel engine 1 is discharged into the air through the exhaust bypass passage 8. At this time, the heaters HA and HB are energized one by one (for example, the particulate filter 5A first), and the air pumps 9 to 2 are connected to the branch passages 2A or 2B having the energized particulate filter. The next air is supplied, and the particulates trapped in the particulate filter 5A or 5B are burned. Then, the combustion gas is released from the combustion gas discharge passage 7 into the air.

When the present invention is applied to the exhaust gas purifying apparatus 30 for an internal combustion engine that operates as described above, there are the following four cases, and the operation of the device of the present invention in each case will be described. (1) While the heater HA is energized, the ignition switch IG
In this case, the operation of the internal combustion engine is stopped after the energization of the heater HA is completed. After that, the particulate filter 5A
The electric air pump 9 is operated until the regeneration of is completed. The energization of the heater HB and the regeneration of the particulate filter 5B are not performed, and the energization of the heater HB and the particulate filter 5B are performed when the ignition switch IG is turned on next time.
Is played.

(2) When the ignition switch IG is turned off during regeneration after the heater HA is energized In this case, the internal combustion engine is stopped, and the electric air pump 9 is operated until the regeneration of the particulate filter 5A is completed. Energization of heater HB, particulate filter 5
B is not reproduced, and the next ignition switch I
When G is turned on, power is supplied to the heater HB and regeneration of the particulate filter 5B is performed.

(3) When the ignition switch IG is off while the heater HB is energized In this case, the operation of the internal combustion engine is stopped after the energization of the heater HB is completed. After that, the particulate filter 5B
The electric air pump 9 is operated until the regeneration of is completed. (4) an internal combustion engine in this case if the ignition switch IG is turned off during playback after heater HB energization is stopped, the electric air pump 9 is operated until the end of the reproduction of the particulate filter 5B.

The control of energization of the heaters HA and HB and the control of each of the particulate filters 5A and 5B are shown in FIG.
3 can be performed in the same manner as the control of the heater H and the particulate filter 5 in
Here, the description is omitted. In the above-described embodiment, the description has been made on the assumption that the electric heater is used as the heating means. However, the heating means may be a burner.

[0032]

As described above, according to the present invention,
Even if the ignition switch of the engine is turned off during the regeneration of the particulate filter, the regeneration of the particulate filter in the regeneration state is completed without imposing a burden on the battery and without causing a problem of fuel consumption or noise. There is an effect that can be.

[Brief description of the drawings]

FIG. 1 is a principle configuration diagram showing a configuration of an exhaust gas purification device for an internal combustion engine of the present invention.

FIG. 2 is a system diagram showing an entire configuration of an embodiment of an exhaust gas purifying apparatus for an internal combustion engine according to the present invention.

FIG. 3 is a flowchart illustrating an example of an operation of a control circuit in the exhaust gas purification device for an internal combustion engine of FIG. 1;

FIG. 4 is a waveform chart showing the operation of each part of the exhaust gas purification device for an internal combustion engine of FIG. 2;

FIG. 5 is a diagram showing a main configuration of a dual type exhaust gas purification apparatus to which the present invention is applied.

FIG. 6 is a system diagram showing the entire configuration of a conventional exhaust gas purification device for an internal combustion engine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Diesel engine 2 ... Exhaust gas passage 3 ... Casing 5, 5A, 5B ... Particulate filter 6 ... Secondary air supply passage 7 ... Combustion gas discharge passage 8 ... Bypass passage 9 ... Electric air pump 10 ... Conventional exhaust purification device 11 ... Battery 12 ... Parking brake lock mechanism 20 ... Exhaust gas purifier of one embodiment of the present invention 30 ... Dual filter type exhaust gas purifier implementing the present invention 100 ... Control circuit H, HA, HB ... Electric heater HR ... Heater relay IG: Ignition switch BS: Backup switch SP1, SP2: Pressure sensor V1-V6: Valve

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Terutaka Kageyama 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Inside of Denso Co., Ltd. (56) References Japanese Utility Model No. 2-145613 (JP, U) Japanese Utility Model Sho-62 −128108 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F01N 3/08-3/38 F01N 9/00 F01N 11/00 F01N 3/02-3/038

Claims (1)

(57) [Claims] A filter provided in an exhaust gas passage of an internal combustion engine collects particulates in exhaust gas,
When the regeneration of the filter is necessary, heating is performed by a heating unit to ignite the particulates in the filter, and at the same time, a regeneration gas is supplied by a regeneration gas supply unit and burned, thereby purifying the exhaust gas. In the apparatus, the regeneration state of the filter for detecting the regeneration state of the filter
A detecting means, the operating state <br/> detecting means of the heating means for detecting the operating state of the heating means, and an ignition switch state detecting means for detecting the on-off state of the ignition switch of the internal combustion engine, the ignition switch is turned on When the heating means is in the operating state when the internal combustion engine is turned off.
While maintaining the operation, the operating system of the internal combustion engine the operation of the heating means to stop the operation of the internal combustion engine to be turned off
When the ignition switch is turned off from the on state, and when the filter is in the regeneration state, regeneration gas supply operation means for maintaining the operation of the regeneration gas supply means until the regeneration state ends. An exhaust purification device for an internal combustion engine, wherein the exhaust purification device is provided.