JPH06280685A - Exhaust particulate removing device of diesel engine - Google Patents

Abstract

PURPOSE:To properly control an EGR(exhaust gas recirculation) for reducing the formation of NOx by controllably correcting the EGR amount according to an amount of secondary air returned to an intake path in the regeneration of a particulate collecting filter. CONSTITUTION:When an amount of particulates collected in filters 5A, 5B exceeds a predetermined value and a differential pressure value detected by a differential pressure sensor 10 between the upstream and downstream of filters 5A, 5B exceeds a reference value, the regenerative process for the filters are practiced. Then, an exhaust particulate removing device 21 closes an intake controlling valve V0 in the regeneration of the filters 5A, 5B to generate negative pressure in an intake path 1A. While secondary air supplied to the filters 5A, 5B by such negative pressure is introduced from an atmospheric opening end of a regenerating gas feed pipe 7, an actual amount Ga of intake is reduced by filter regenerating combustion gas introduced in the intake path 1A to accordingly correct and EGR amount. As a result, the amount of EGR is properly held even if the filters 5A, 5B are practically regenerated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diesel engine exhaust particulate removal device, and more particularly, to a diesel engine that performs EGR (exhaust gas recirculation) while the engine is operating and returns the regeneration gas of the filter to the intake passage of the engine. The present invention relates to an exhaust particulate removal device for a diesel engine, which can appropriately control the EGR amount during filter regeneration.

[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.

[0003] In an exhaust particulate removing device configured to remove particulates by a ceramic particulate filter (hereinafter simply referred to as a filter) arranged in an exhaust passage of a diesel engine, the particulates are removed inside the filter. As the amount of particulates collected increases, the air permeability is gradually lost and engine performance deteriorates. Therefore, the filter in which the particulates are collected to some extent ignites the particulates collected in the filter by an electric heater or the like, and a regeneration gas such as secondary air is supplied to burn the particulates to periodically burn the particulates. To be regenerated.

The judgment of the regeneration time is generally made by detecting the amount of particulates trapped in the filter. The amount of collected particulates in the filter is usually detected by the pressure of the exhaust gas on the upstream side of the filter and the pressure difference (pressure loss) on the downstream side, and the pressure loss value exceeds a predetermined value. It is judged that it is time to regenerate, depending on the time. Then, when the filter is regenerated, secondary air is generally supplied, and the particulates trapped in the filter are burned. Combustion gases are generally released to the atmosphere, but may be returned to the intake passages of the engine.

The secondary air is generally supplied by using an electric air pump, but instead of the electric air pump, the exhaust pipe of the combustion gas of the filter is connected to the downstream side of the intake valve provided in the intake passage of the engine to intake air. There is also one that supplies secondary air by negative pressure generated in the intake passage on the valve downstream side (for example,
See JP-A-62-178709). On the other hand, there is a diesel engine equipped with the exhaust particulate removal device as described above, which includes an EGR device. The EGR device is a means for reducing NOx in the exhaust gas, and recirculates part of the inactive exhaust gas into the intake passage to mix it with intake air to lower the maximum temperature during combustion, thereby reducing NOx.
It is a device that reduces the generation of. In order to work the EGR more effectively and reduce NOx, the EGR device is provided with a flow rate control valve called an EGR valve in the middle of the pipe line that returns the exhaust gas to the intake passage, depending on the operating state. Part of the most suitable amount of exhaust gas is returned to the intake side.

[0006]

However, the EGR
In a diesel engine that performs EGR while the engine is operating by means of a device, secondary air for regeneration of a particulate filter (regenerated combustion gas of the filter) is disclosed in JP-A-62-1787.
When the technique described in Japanese Patent Publication No. 09 is used to introduce the gas into the intake passage side, the amount of EGR fluctuates, and the problem that NOx generation cannot be properly suppressed occurs.

Therefore, the present invention solves the problems of the conventional exhaust particulate removal system for diesel engines,
In a diesel engine that performs R, in which the combustion gas of a particulate filter is returned to the intake passage side, even if secondary air is returned to the intake passage of the engine when the filter is regenerated, the EGR amount can be controlled. Done correctly, NOx
An object of the present invention is to provide a device for removing exhaust particulates of a diesel engine, which can reduce the generation of exhaust gas.

[0008]

According to a first aspect of the present invention, which achieves the above object, an exhaust particulate removing device for a diesel engine collects particulates in exhaust gas by a filter provided in an exhaust passage of an internal combustion engine. An exhaust particulate removal device for a diesel engine that supplies secondary air to the filter at a predetermined time to perform combustion regeneration of the filter, performs EGR control when the engine is operating, and returns regeneration combustion gas to the intake passage of the engine. According to the amount of secondary air returned to the intake passage during regeneration of the filter, the EGR
It is characterized in that the amount is corrected and controlled.

Further, in the exhaust gas particulate remover for the diesel engine of the second aspect of the present invention which achieves the above object, the particulate matter in the exhaust gas is collected by the filter provided in the exhaust passage of the internal combustion engine, and the particulate matter is exhausted at a predetermined time. A diesel engine exhaust particulate removal device for supplying secondary air to the filter for combustion regeneration of the filter, wherein EGR control is performed during engine operation, and regenerated combustion gas is returned to the intake passage of the engine. The exhaust passage of the engine is provided with an oxygen concentration detecting means for detecting the oxygen concentration in the exhaust gas, and an operating state detecting means for detecting the operating state of the engine is provided, so that the oxygen concentration in the exhaust gas varies depending on the operating state of the engine. It is characterized in that the EGR amount is controlled so as to become a predetermined value.

Further, the particulate matter in the exhaust gas is collected by the filter provided in the exhaust passage of the internal combustion engine of the third aspect of the present invention for achieving the above object, and the secondary air is supplied to the filter at a predetermined time. In a diesel engine exhaust particulate removal device that performs combustion regeneration of a filter by performing EGR control when the engine is operating and returning regenerated combustion gas to the intake passage of the engine, the actual intake air in the intake passage of the internal combustion engine Intake air amount detecting means for detecting the amount, accelerator opening detecting means for detecting the accelerator opening of the engine, engine speed detecting means for detecting the number of revolutions of the engine, depending on the accelerator opening and the number of revolutions of the engine Target intake air amount calculating means for calculating the target intake air amount, and an EGR valve for controlling the EGR amount by the opening degree of the EGR valve so that the actual intake air amount becomes the target intake air amount. It is characterized by providing a control means.

[0011]

According to the exhaust particulate matter removal device for a diesel engine of the first aspect of the present invention, the EGR amount is corrected and controlled in accordance with the amount of secondary air returned to the intake passage when the filter is regenerated. The EGR amount is properly maintained. Also, according to the exhaust particulate matter removal device for a diesel engine of the second aspect of the present invention, the oxygen concentration in the exhaust gas of the engine is detected by the oxygen concentration detection means, and the engine state detected by the operating state detection means is detected. The EGR amount is controlled so that the oxygen concentration in the exhaust gas reaches a predetermined value according to the operating state.

Further, according to the exhaust gas particulate remover of the diesel engine of the third aspect of the present invention, the actual intake air amount is detected in the intake passage of the internal combustion engine by the intake air amount detecting means, and the accelerator opening degree detecting means. Thus, the accelerator opening degree of the engine is detected, and the engine speed detecting means detects the engine speed. Then, the EGR amount is E so that the actual intake air amount becomes equal to the target intake air amount calculated according to the accelerator opening degree and the engine speed of the engine by the target intake air amount calculating means.
It is controlled by the opening of the GR valve.

[0013]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows the configuration of an exhaust particulate removal device 21 for a diesel engine according to a first embodiment of the present invention, and shows a schematic configuration of an exhaust particulate removal device of the simultaneous collection and reverse flow alternate regeneration dual filter type. Is.

The intake air (intake air) is supplied to the engine 1 equipped with the exhaust particulate remover 21 of the first embodiment by the intake passage 1
It is done through A. An air cleaner 4 is provided on the atmosphere opening side of the intake passage 1A, and an air flow meter 9, an intake control valve V0, and a pressure sensor for measuring the intake amount are sequentially provided in the intake passage 1A downstream of the air cleaner 4 from the upstream side. SP is provided. The detected value Ga of the intake air amount by the air flow meter 9 and the pressure detected value AP from the pressure sensor SP are both input to an ECU (control circuit) 100 described later, and the opening of the intake control valve V0 is controlled by the control circuit 100. It

Exhaust passage 2 for guiding exhaust gas from engine 1
Are branched into branch pipes 2A and 2B at a branch portion a, are then merged at a merge portion b, and are connected to the muffler 6 by an exhaust passage 2D. 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.

The engine 1 of this embodiment is provided with an EGR device, and an exhaust gas recirculation pipe 12 connecting the exhaust passage 2D and the intake passage 1A is provided downstream of the junction b of the branch pipes 2A and 2B. is there. An EGR control valve V4 whose opening is controlled by the control circuit 100 is provided in the exhaust gas recirculation pipe 12. In this embodiment, the exhaust gas recirculation pipe 12 is connected to the exhaust passage 1A downstream of the intake control valve V0.

The above-mentioned filters 5A and 5B are honeycomb filters having partition walls made of a porous material such as ceramics and generally have a cylindrical shape, and have a large number of rectangular parallelepiped passages (filters) surrounded by partition walls. Cell). And
Adjacent ones of these passages are closed passages that are alternately plugged with ceramic plugs (plugs) on the exhaust gas inflow side and the exhaust gas outflow side. Therefore, the particulates in the exhaust gas flowing into the filters 5A and 5B are collected by the filter cell when the exhaust gas passes through the wall surface of the filter cell.

Further, pressure introducing pipes SPU and SPD are provided on the upstream side of the branch portion a of the branch pipes 2A and 2B and on the downstream side of the joining portion b, respectively, and the differential pressure sensor 10 is provided upstream of the branch portion a. The pressure on the side and the pressure on the downstream side of the merging portion b are introduced. Then, the differential pressure (pressure loss) PD 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 control circuit 100. The control circuit 100 determines the regeneration timing of the filters 5A and 5B based on this differential pressure.

On the other hand, electric heaters HA and HB for heating the filter and igniting the particulates at the plug member (not shown) near the downstream end face of the filters 5A and 5B or at the downstream end portion are regenerated. The electric heaters HA and HB have one end grounded and the other end connected to the battery 11 via switches SWA and SWB controlled by the control circuit 100. Furthermore, filter 5
A temperature sensor ST that detects the exhaust gas temperature is provided on the upstream side of A and 5B, and the output T of this temperature sensor ST
hE is also input to the control circuit 100. Although not shown, the engine 1 is provided with an intake air temperature sensor for detecting the intake air temperature and a water temperature sensor for detecting the temperature of the engine 1 by the water temperature. The intake air temperature ThA and the water temperature ThW from these sensors are provided. Is also input to the control circuit 100.

The branch portion 2a, 2B is provided with a flow of the exhaust gas from the exhaust passage 2 on the upstream side of the branch portion a.
And a second control valve V2 for switching connection of the branch pipes 2A and 2B to the exhaust passage 2D on the downstream side of the merging portion b.
Both of the control valves V1 and V2 are driven by the control circuit 100, and the control valves V1 and V2 are controlled by a control signal from the control circuit 100 so that the branch pipes 2A and 2B are not closed, or a branch position. It is positioned at a position where either one of the tubes 2A and 2B is closed.

At the time of reproducing the above-mentioned filters 5A and 5B,
It is necessary to energize the electric heater HA or HB, to flow the regeneration gas from the downstream side of the energized side of the filter 5A or the filter 5B, and to discharge the combustion gas from the upstream side. Therefore, in this embodiment, the branch pipe 2
A regeneration gas supply pipe 7 is provided between the merging portion b of A and 2B and the filters 5A and 5B, and one end of the regeneration gas supply pipe 7 is open to the atmosphere. Further, on-off valves V5 and V6 are provided at the connecting portions of the regeneration gas supply pipe 7 to the branch pipes 2A and 2B, respectively. In addition, branch pipe 2
A combustion gas exhaust pipe 8 is provided between the branch portion a of A and 2B and the filters 5A and 5B.
One end of the intake passage 1A of the engine 1 via the flow rate adjusting valve V3.
Is connected to the downstream side of the intake control valve V0. Further, opening / closing valves V7 and V8 are provided at the connecting portions of the combustion gas discharge pipe 8 to the branch pipes 2A and 2B, respectively. The valves V3 and V5 to V8 are all driven and controlled by the control circuit 100.

The valves V0 to V8 described above are actually driven by a diaphragm actuator, a negative pressure switching valve, or an electric actuator, but the driving mechanism is not particularly limited. So
Here, illustration and description thereof are omitted. However, in the present invention, it is necessary to switch some of the valves V0 to V8 immediately when the engine is started. Therefore, when a diaphragm actuator or a negative pressure switching valve is used, a control drive of a negative pressure pump or the like is performed in the vehicle. Source must 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 processes, a random number. Access memory RAM, read-only memory ROM, backup memory B-RA that retains data even when the engine key switch is turned off
Although it is composed of a microcomputer including M, the output circuit OUT, and the bus line 111 connecting them, detailed description of the operation of the structure will be omitted.

The interface INa for inputting an analog signal of the control circuit 100 has an intake air amount Ga, an intake air pressure AP in the intake passage 1A, a differential pressure signal PD of exhaust gas upstream and downstream of the particulate filters 5A and 5B. , An intake air temperature signal ThA, a water temperature signal ThW of the engine 1 and an accelerator opening θ from a not-shown accelerator pedal depression amount detection sensor
Interface IN for inputting the engine speed signal Ne and the like from the acc and the speed sensor, and for inputting a digital signal
A signal or the like from the key switch is input to d.

Next, the operation of the exhaust particle removing device 21 of the diesel engine of the embodiment constructed as described above will be explained. [When collecting particulates in exhaust gas] Intake control valve V
0 is opened, and the control valves V1 and V2 are controlled to the neutral position. Further, the flow control valve B3 is in the closed state, and the EGR
The control valve V4 controls the control circuit 100 according to the operating state of the engine 1.
And the on-off valves V5 to V8 are closed.
In this state, the exhaust gas discharged from the diesel engine 1 flows into both the branch pipes 2A and 2B as shown by the solid arrows, and the particulates are removed by the filters 5A and 5B, and a part of the exhaust gas of the EGR device is removed. It is returned to the intake passage 1A side through the exhaust gas recirculation pipe 12, and the rest is discharged into the atmosphere through the muffler 6. [During filter regeneration] When the amount of particulates trapped in the filters 5A and 5B exceeds a predetermined value, and the differential pressure detection values of the differential pressure sensor 10 on the upstream and downstream sides of the filters 5A and 5B exceed a reference value. The filter regeneration process is executed from the filter 5A. During regeneration of the filter 5A, the intake control valve V0 closes the intake passage 1A as shown by the dotted line to generate a negative pressure on the downstream side thereof, and the control valves V1 and V2 connect the branch pipe 2A.
The inlet side and the outlet side are closed, and the flow rate control valve V3 and the open / close valves V5 and V7 are opened. Due to the negative pressure in the intake passage 1A, the secondary air is supplied with the regeneration gas supply pipe 7 as shown by the dotted arrow.
Is sucked from the open end of the atmosphere and is supplied to the filter 5A through the regeneration gas supply pipe 7. In this state, the heater HA is energized to burn the particulates in the filter 5A, and the combustion gas is returned to the intake passage 1A through the combustion gas discharge pipe 8 provided with the flow rate adjusting valve V3.

During regeneration of the filter 5B, the control valves V1 and V
2 switches so as to close the inlet side and the outlet side of the branch pipe 2B, the open / close valves V5 and V7 are switched from the open state to the closed state, and the open / close valves V6 and V8 are switched from the closed state to the open state. The other valves V0, V3 and V4 do not switch. In this state, the secondary air sucked from the atmospheric opening end of the regeneration gas supply pipe 7 by the negative pressure in the intake passage 1A is supplied to the filter 5B, the heater HB is energized, and the particulates in the filter 5B are removed. The combustion gas is combusted and is returned to the intake passage 1A through the combustion gas discharge pipe 8 provided with the flow rate adjusting valve V3.

In the above operation, the filter 5A
Alternatively, when the regenerated combustion gas of 5B is recirculated to the intake passage 1A, the EGR amount is affected by the recirculation amount. Therefore, the control circuit 100 needs to correct the EGR amount during regeneration of the filter with respect to that during non-regeneration. 2 shows the control circuit 1
00 depending on whether the filter is regenerated during engine operation
The procedure for controlling the GR amount is shown and is executed at predetermined time intervals.

While the engine is operating, the control circuit 100 always executes step 201 in which the engine speed Ne and the accelerator opening θ are set.
Read the detected values of acc and intake air amount Ga. And
In step 202, the intake control valve V of the intake passage 1A
It is determined whether 0 is fully opened. This is because the base map of the basic value (target value, hereinafter referred to as target intake amount) Gao of the intake amount to be used for EGR control is different between when the intake control valve V0 is fully open and when it is not. is there. EG
When the intake control valve V0 is not fully open during R control,
This is a case where the EGR amount does not exceed the predetermined value even if the EGR rate is increased to 100%. At this time, the intake control valve V0 is closed to generate a negative pressure in the intake passage 1A, and the EGR amount is further increased. .

When the intake control valve V0 is fully open, the routine proceeds to step 203, where the engine speed N indicating the operating state of the engine is reached.
The target intake air amount Gao is calculated from e and the accelerator opening θacc by using the fully open base map shown in FIG. 4 (a). When the intake control valve V0 is not fully open, the routine proceeds to step 204, where the target is determined from the engine speed Ne indicating the operating state of the engine and the accelerator opening θacc using the non-fully open base map shown in FIG. 4 (b). The intake air amount Gao is calculated.

In the following step 205, step 201
The value of the intake air amount Ga read at step (hereinafter referred to as the actual intake air amount) is ± α from the target intake air amount Gao obtained by the calculation.
Whether it is within the range is determined by the formula | Ga | ≦ Gao ± α. When the actual intake air amount Ga is within the target intake air amount Gao ± α, the EGR amount is considered to be appropriate and the process proceeds to step 209 to determine whether the filter is being regenerated. Then, if the filter is not being regenerated, this routine is finished as it is.

On the other hand, in step 205, when the actual intake air amount Ga is not within the target intake air amount Gao ± α, the routine proceeds to step 206, where it is determined whether the actual intake air amount Ga is larger than the target intake air amount Gao. Then, when Ga> Gao, it is determined that the EGR amount is small and the routine proceeds to step 207, where E
The opening degree of the GR control valve V4 is increased and the process proceeds to step 209. On the contrary, when Ga <Gao, it is determined that the EGR amount is large, and the process proceeds to step 208, where the opening amount of the EGR control valve V4 is reduced and the step is performed. Proceed to 209. In step 209, it is determined whether or not the filter is being reproduced, and if it is not being reproduced, this routine is ended as it is, but if it is being reproduced, the processing proceeds to step 211 and thereafter to execute the processing being reproduced.

In step 211, the intake control valve V0 is controlled in the closing direction to generate a negative pressure on the downstream side of the intake control valve V0. Then, in step 212, the negative pressure AP of the intake passage 1A is detected, and it is determined in step 213 whether or not the value is smaller than the reference value APref. AP <A
If it is Pref, it is determined that the negative pressure in the intake passage 1A is sufficient, and the routine proceeds to step 210, where the opening degree of the secondary air flow rate control valve V3 is set, and this routine is ended. Also, AP
If ≧ APref, it is determined that the negative pressure in the intake passage 1A is not sufficient, and the routine proceeds to step 214, further closes the opening degree of the intake control valve V0, and then proceeds to step 210 to set the opening degree of the secondary air flow rate control valve V3. The lever ends this routine.

As described above, in the exhaust particle removing device 21 of the diesel engine equipped with the EGR device of this embodiment, when the filter is regenerated, the intake control valve V0 is closed to generate a negative pressure in the intake passage 1A. , While introducing the secondary air supplied to the filter with this negative pressure from the atmosphere,
When the actual intake air amount Ga decreases due to the regenerated combustion gas of the filter introduced into the intake passage, the EGR amount is corrected accordingly. As a result, even if the filter is regenerated, E
The GR amount is properly maintained.

FIG. 3 shows another embodiment of the control procedure of the EGR amount of the control device 100 in the exhaust particulate removal device 21 of the diesel engine of FIG. In the procedure of this embodiment, the amount of oxygen contained in the regenerated combustion gas introduced into the intake passage 1A at the time of regeneration of the filter is more dependent on the exhaust gas recirculated to the intake passage 1A by the EGR device depending on the operating state of the engine. Since the amount of oxygen is larger than the amount of oxygen contained, the EGR amount is not increased or decreased with respect to the regenerated combustion gas introduced into the intake passage 1A in a one-to-one manner, but the EGR amount is corrected according to the operating state of the engine when the filter is regenerated. Then, it increases or decreases.

The control procedure of the embodiment of FIG. 3 is different from the control procedure of FIG. 2 in that the calculation process of the target intake air amount Gao in step 204 is performed using another correction base map while the filter is regenerating. Only. Therefore, in the control procedure of FIG. 3, the same steps as those in FIG. 2 are designated by the same step numbers and the description thereof is omitted. In the control of FIG. 3, when it is determined in step 202 that the intake control valve V0 is not fully closed, the process proceeds to step 301, and it is determined whether the filter is being regenerated. Then, when the filter is not being regenerated, the routine proceeds to step 204 similarly to the control of FIG. 2, and the target intake air amount Gao is calculated using the base map at the time when the valve is not fully opened in FIG. 4B, but when the filter is regenerating. If so, go to step 302, and see FIG. 4 (c).
The target intake air amount Gao is calculated using the corrected base map of.

The corrected base map differs from the non-fully open base map shown by the dotted line in FIG. 4 (b) in the characteristics of the engine load. This does not change because the intake control valve V0 is originally in the fully open state when the accelerator opening θacc is large and the load is high, and when the accelerator opening θacc is small and the load is light, exhaust gas and regenerated combustion gas of the filter are regenerated. Since the oxygen concentrations are not so different and can be regarded as the same, the correction base map is set such that the target intake air amount Gao is slightly increased only when the engine has a medium load.

As described above, in the control procedure of FIG. 3, the EGR amount is finely corrected according to the operating state of the engine at the time of filter regeneration, so that the EGR amount is appropriately maintained even when the filter regeneration is executed. . FIG. 5 shows the configuration of an exhaust particulate removal device 22 for a diesel engine according to a second embodiment of the present invention, and shows a schematic configuration of an exhaust particulate removal device of the simultaneous collection and reverse flow alternate regeneration dual filter type. Is. The exhaust particulate remover 22 of the second embodiment is the first
The difference from the exhaust particle removing device 21 of the embodiment is only the control of the intake control valve V0. That is, in the exhaust particulate removal device 21 of the first embodiment, the negative pressure in the intake passage 1A is detected by using the pressure sensor SP to control the intake control valve V0, but the exhaust particulate of the second embodiment is controlled. The removal device 22 is different in that the differential pressure sensor 20 detects the differential pressure between the negative pressure in the intake passage 1A and the pressure in the exhaust passage 2D. Since the other configurations of the exhaust particle removing device 22 of the second embodiment are the same as the configurations of the first embodiment,
The same components are designated by the same reference numerals and the description thereof will be omitted.

Further, the control procedure of the EGR amount by the control circuit 100 in the exhaust particulate removal device 22 of the second embodiment depending on the presence or absence of regeneration of the filter during engine operation is almost the same as the flowcharts shown in FIGS. Since they are the same, the same steps will be denoted by the same step numbers, and the description thereof will be omitted. Only different steps will be described. The flow chart of FIG. 6 is for executing the same control as the flow chart shown in FIG. 2 in the exhaust particulate removal device 22 of the second embodiment. In the procedure of FIG. 2, the negative pressure AP of the intake passage 1A is detected in step 212, and step 213
In the procedure of FIG. 3, it is determined whether the value is smaller than the reference value APref in step 601 instead of step 212.
The differential pressure ΔP is detected and it is determined in step 602, which is an alternative to step 213, whether the value of the differential pressure ΔP is smaller than the reference value ΔPref. When ΔP <ΔPref, the routine proceeds to step 210, where the opening degree of the secondary air flow rate control valve V3 is set, and this routine is ended. If ΔP ≧ ΔPref, the routine proceeds to step 214, further closes the opening degree of the intake control valve V0, and then proceeds to step 210, sets the opening degree of the secondary air flow rate control valve V3, and terminates this routine.

The flow chart of FIG. 7 shows a case where the same control as that of the flow chart shown in FIG. 3 is executed in the exhaust particulate removal device 22 of the second embodiment. Also in the procedure of FIG. 7, step 6 replacing step 212 of FIG.
The only difference is that the differential pressure ΔP between the intake passage 1A and the exhaust passage 2D is detected at 01 and whether or not the value of the differential pressure ΔP is smaller than the reference value ΔPref at step 602 instead of step 213.

FIG. 8 shows the structure of an exhaust particle removing device 23 for a diesel engine according to a third embodiment of the present invention. The schematic structure of the simultaneous collecting and reverse flow alternate regeneration dual filter type exhaust particle removing device is shown. Is shown. The exhaust particulate remover 23 of the third embodiment is different from the exhaust particulate remover 22 of the second embodiment in that the EGR amount is controlled not by the intake air amount Ga but by an oxygen concentration sensor (not shown) provided in the exhaust passage 2. Lean sensor) The only thing to do is SO2.
That is, in the exhaust particulate removal device 22 of the second embodiment, the differential pressure sensor 20 detects the differential pressure between the negative pressure in the intake passage 1A and the pressure in the exhaust passage 2D, so that the intake control valve V
0, the flow control valve V9 and the EGR valve V10 are controlled to E
Although the GR amount is controlled, in the exhaust particulate removal device 23 of the third embodiment, the air flow sensor in the intake passage 1A is abolished, and the intake control valve V0, by the output of the lean sensor SO2 provided in the exhaust passage 2, Flow control valve V9 and EGR
The difference is that the valve V10 is controlled to control the EGR amount. The rest of the configuration of the exhaust particle removing device 23 of the third embodiment is the same as the configuration of the second embodiment, so the same components are assigned the same reference numerals and explanations thereof are omitted.

FIG. 2 shows a control procedure of the EGR amount by the control circuit 100 depending on the presence or absence of regeneration of the filter during engine operation, which is executed at predetermined time intervals. During operation of the engine, the control circuit 100 reads the engine speed Ne, the accelerator opening θacc, and the oxygen concentration O2G detected by the lean sensor SO2 in step 901 every time. Then, in step 902, the basic value of oxygen concentration (hereinafter referred to as the target oxygen concentration) O2b is calculated from the engine speed Ne representing the operating state of the engine and the accelerator opening degree θacc using a base map (not shown).

In the following step 903, step 901
In the equation | O2G | ≤O2b ±, it is determined whether or not the value of the oxygen concentration O2b (hereinafter referred to as the actual oxygen concentration) read in is within ± β from the target oxygen concentration O2b obtained by the calculation.
Determine by β. The actual oxygen concentration O2G is the target oxygen concentration O
If it is within 2b ± β, it is considered that the EGR amount is appropriate and the routine proceeds to step 907, where it is judged whether or not the filter is being regenerated. Then, if the filter is not being regenerated, this routine is finished as it is.

On the other hand, in step 903, when the actual oxygen concentration O2G is not within the target oxygen concentration O2b ± β, the routine proceeds to step 904, where it is determined whether the actual oxygen concentration O2G is higher than the target oxygen concentration O2b. And O2G> O
When it is 2b, it is determined that the EGR amount is small, and the routine proceeds to step 905, where the opening degree of the EGR control valve V4 is increased and step 9 is performed.
On the contrary, when O2G <O2b, it is judged that the EGR amount is large and the routine proceeds to step 906, where the opening degree of the EGR control valve V4 is made small and the routine proceeds to step 907. Step 907
Then, it is determined whether or not the filter is being reproduced, and if it is not being reproduced, this routine is ended as it is. If it is being reproduced, the routine proceeds to step 909 and thereafter to execute the processing being reproduced.

In step 909, the intake control valve V0 is controlled in the closing direction to generate a negative pressure on the downstream side of the intake control valve V0. Then, in step 910, the differential pressure ΔP between the intake passage 1A and the exhaust passage 2D is detected, and the detected value is the reference value ΔP.
In step 911, it is determined whether it is smaller than ref. If ΔP <ΔPref, it is determined that the negative pressure in the intake passage 1A is sufficient, and the routine proceeds to step 908, where the opening degree of the secondary air flow rate control valve V3 is set, and this routine is ended. If ΔP ≧ ΔPref, it is determined that the negative pressure in the intake passage 1A is not sufficient, and the routine proceeds to step 912, further closes the opening degree of the intake control valve V0, and then proceeds to step 908, 2
The opening degree of the next air flow rate control valve V3 is set, and this routine ends.

As described above, in the exhaust particle removing device 23 of the diesel engine equipped with the EGR device of this embodiment, when the filter is regenerated, the intake control valve V0 is closed to generate a negative pressure in the intake passage 1A. , While introducing the secondary air supplied to the filter with this negative pressure from the atmosphere,
When the actual oxygen concentration O2G is reduced by the regenerated combustion gas of the filter introduced into the intake passage, the EGR amount is corrected accordingly. As a result, the EGR amount is appropriately maintained even when the oxygen concentration in the regenerated combustion gas changes when the regeneration of the filter is executed.

FIG. 10 shows the construction of an exhaust particulate remover 24 for a diesel engine according to a fourth embodiment of the present invention, and is a schematic construction of an exhaust particulate remover of a simultaneous collection and reverse flow alternate regeneration dual filter type. Is shown. The exhaust particle removing device 24 of the fourth embodiment is obtained by adding an air flow meter 9 to the exhaust particle removing device 23 of the third embodiment. Exhaust particulate removal device 2 of this embodiment
At 4, the lean sensor SO2 detects the oxygen concentration O2G in the exhaust passage 2, and the actual EGR amount is calculated and fed back together with the output from the air flow meter 9 to obtain the EGR.
It controls the quantity.

Although the present invention has been described above with respect to four embodiments of the simultaneous collection and reverse flow alternate regeneration dual filter type exhaust particulate removal apparatus, the exhaust particulate removal apparatus of the present invention is applicable to other types of exhaust particulate removal apparatus. Is also applicable. That is, the present invention can be applied to a simultaneous collection forward flow alternate regeneration dual filter type, an alternating capture reverse flow or forward flow alternate regeneration dual filter type, or a single filter type exhaust particulate removal device. Further, although the exhaust gas intake port of the EGR device is opened on the downstream side of the particulate filter in the above-mentioned embodiment, it may be opened on the upstream side of the particulate filter. However, when the intake port of the exhaust gas of the EGR device is opened upstream of the particulate filter, the back pressure differs depending on the amount of particulates trapped in the filter, so that correction is necessary.

[0048]

As described above, according to the exhaust gas particulate remover for the diesel engine of the first embodiment of the present invention, the EGR amount is changed according to the amount of the secondary air returned to the intake passage when the filter is regenerated. Is corrected and controlled, so that the EGR amount is appropriately maintained. Also, according to the exhaust particulate matter removal device for a diesel engine of the second aspect of the present invention, the EG is adjusted so that the oxygen concentration in the exhaust gas becomes a predetermined value according to the operating state of the engine.
Since the R amount is controlled, the EGR amount is maintained properly. Furthermore, according to the exhaust particulate matter removal device for a diesel engine of the third aspect of the present invention, the actual intake air amount becomes the target intake air amount calculated according to the accelerator opening and the engine speed of the engine. Since the EGR amount is controlled by the opening degree of the EGR valve, the EGR amount is maintained properly.

As described above, according to the present invention, in the diesel engine for performing EGR, in which the combustion gas of the particulate filter is returned to the intake passage side, when the filter is regenerated, the secondary air is introduced into the intake passage of the engine. Even if the temperature is returned to, the EGR amount is correctly controlled, and it is possible to reduce the generation of NOx.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a first embodiment of an exhaust particulate removal device of the simultaneous collection and reverse flow alternate regeneration dual filter type of the present invention.

FIG. 2 is a flowchart showing a procedure of an EGR control operation during engine operation of the control circuit of FIG.

FIG. 3 is a flowchart showing another procedure of EGR control operation during engine operation of the control circuit of FIG.

FIG. 4 (a) is a base map for calculating a target intake air amount when the intake control valve is fully opened, and (b) is a base map for calculating a target intake air amount when the intake control valve is not fully opened. Yes, (c) is a base map for calculating the target intake air amount when the intake control valve at the time of filter regeneration is not fully opened.

FIG. 5 is a diagram showing a schematic configuration of a second embodiment of an exhaust particulate removal device of the simultaneous collection and reverse flow alternate regeneration dual filter type of the present invention.

6 is a flowchart showing a procedure of an EGR control operation during engine operation of the control circuit of FIG.

7 is a flowchart showing another procedure of EGR control operation during engine operation of the control circuit of FIG.

FIG. 8 is a diagram showing a schematic configuration of a third embodiment of the simultaneous collection and reverse flow alternate regeneration dual filter type exhaust particulate removal device of the present invention.

9 is a flowchart showing a procedure of an EGR control operation during engine operation of the control circuit of FIG.

FIG. 10 is a diagram showing a schematic configuration of a fourth embodiment of an exhaust particulate removal device of the simultaneous collection and reverse flow alternate regeneration dual filter type of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Diesel engine 1A ... Intake passage 2, 2D ... Exhaust passage 2A, 2B ... Branch pipe 5A, 5B ... Filter 7 ... Regeneration gas supply pipe 8 ... Combustion gas exhaust pipe 9 ... Air flow meter 10, 20 ... Differential pressure sensor 12 Exhaust gas recirculation pipe 100 ... Control circuit a ... Branching part b ... Joining part HA, HB ... Electric heater SO2 ... Oxygen concentration sensor (lean sensor) SP ... Pressure sensor V0-V10 ... Valve

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location F02D 41/14 310 C 8011-3G

Claims (3)

[Claims] 1. Exhaust particulates of a diesel engine for collecting particulates in exhaust gas by a filter provided in an exhaust passage of an internal combustion engine and supplying secondary air to the filter at a predetermined time to perform combustion regeneration of the filter. A removal device that performs EGR control during engine operation and returns regenerated combustion gas to the intake passage of the engine, wherein the EGR is adjusted according to the amount of secondary air returned to the intake passage during regeneration of the filter. An exhaust particulate removal device for diesel engines, characterized by correcting and controlling the amount. 2. Exhaust particulates of a diesel engine for collecting particulates in exhaust gas by a filter provided in an exhaust passage of an internal combustion engine and supplying secondary air to the filter at a predetermined time to perform combustion regeneration of the filter. In the removal device, which performs EGR control at the time of engine operation and returns the regenerated combustion gas to the intake passage of the engine, an oxygen concentration detection means for detecting the oxygen concentration in the exhaust gas is provided in the exhaust passage of the engine, A device for detecting the operating state of the engine, and controlling the EGR amount so that the oxygen concentration in the exhaust gas reaches a predetermined value according to the operating state of the engine, the exhaust particulate removal device for a diesel engine . 3. Exhaust particulates of a diesel engine for collecting particulates in exhaust gas by a filter provided in an exhaust passage of an internal combustion engine, and supplying secondary air to the filter at a predetermined time to perform combustion regeneration of the filter. A removal device that performs EGR control during engine operation and returns regenerated combustion gas to the intake passage of the engine. Intake air amount detection means for detecting the actual intake air amount in the intake passage of the internal combustion engine; An accelerator opening detecting means for detecting the accelerator opening, an engine speed detecting means for detecting the engine speed, and a target intake air amount for calculating a target intake air amount according to the accelerator opening and the engine speed. Calculation means and EGR so that the actual intake air amount becomes the target intake air amount
An EGR valve control device for controlling the amount by the opening degree of the EGR valve, and an exhaust particulate removal device for a diesel engine, comprising: