JP2021165546A - Exhaust emission control device for internal combustion engine - Google Patents

Abstract

To appropriately regenerate a particulate filter during a high load operation of an engine.SOLUTION: An exhaust emission control device for an internal combustion engine includes: a waste gate valve device (17) controlling the amount of exhaust gas flowing in a bypass passage (16) bypassing an exhaust turbine (8b); a particulate filter (15) disposed in an exhaust passage (13); an EGR passage (18) connecting the exhaust passage (13) with an engine intake passage; and an EGR gas amount control device. When regeneration of the particulate filter (15) is performed in a high load operating state of the engine, the waste gate valve device (17) and the EGR gas amount control device are controlled to supply part of intake air in the engine intake passage to the particulate filter (15) via the EGR passage (18).SELECTED DRAWING: Figure 4

Description

The present invention relates to an exhaust gas purification device for an internal combustion engine.

It is equipped with an exhaust gas recirculation for supercharging, and an exhaust gas recirculation device, for example, a particulate filter is arranged in the exhaust passage downstream of the exhaust turbine of the exhaust turbocharger, and the exhaust passage between the exhaust turbine and the particulate filter. Is connected to the engine intake passage upstream of the intake compressor of the exhaust turbocharger via the EGR passage, and an EGR valve is arranged in the EGR passage, and the engine intake passage downstream of the intake compressor and the EGR passage upstream of the EGR valve. Is connected via a bypass passage, and a part of the intake air discharged from the intake compressor during high engine load operation or during regeneration of the particulate filter and when the EGR valve is closed. Is supplied into the EGR passage through the bypass passage to cause the EGR passage to flow backward toward the upstream side, and the unburned fuel and condensed water staying in the EGR passage are removed from the EGR passage by the backflowing intake air flow. (See, for example, Patent Document 1).

Japanese Patent No. 4792997

By the way, in order to burn and remove the particulates deposited on the particulate filter, that is, in order to regenerate the particulate filter, air is required. On the other hand, when the fuel supply is temporarily stopped during the deceleration operation of the vehicle, air is supplied to the particulate filter, and therefore, the particulate filter is regenerated at this time. This vehicle deceleration operation is usually repeated frequently, and therefore the regeneration of the particulate filter is usually performed without any problem. However, when the engine high load operation such as towing uphill continues, the particulate filter is not regenerated. Therefore, in such a case, it is necessary to regenerate the particulate filter by some method. In this case, in order to regenerate the particulate filter, it is conceivable to supply a part of the intake air to the particulate filter via the EGR passage.

On the other hand, as described above, in the above-mentioned known internal combustion engine, a part of the intake air is supplied to the particulate filter via the EGR passage. However, in order to blow off the unburned fuel and condensed water staying in the EGR passage by the backflow intake air flow, it is considered necessary to increase the backflow intake air flow considerably, and therefore, in the above-mentioned known internal combustion engine, It is considered that a large amount of intake air flow flows into the particulate filter. However, when a large amount of intake air flow flows into the particulate filter, the particulate filter is overheated, and as a result, the particulate filter may be deteriorated or melted. Further, in the above-mentioned internal combustion engine, it is necessary to additionally install a bypass passage for generating a backflow intake air flow, and therefore, there is a problem that the structure becomes complicated.
An object of the present invention is to provide an exhaust gas purification device for an internal combustion engine having a simple structure and capable of regenerating a particulate filter even during high engine load operation.

According to the present invention, the exhaust turbocharger for supercharging is provided, the exhaust turbine of the exhaust turbocharger is arranged in the engine exhaust passage, and the exhaust passage and the exhaust upstream of the exhaust turbine are bypassed. A bypass passage connecting the exhaust passage downstream of the turbine, a waistgate valve device for controlling the amount of exhaust gas flowing in the bypass passage, a particulate filter arranged in the exhaust passage downstream of the exhaust turbine, an exhaust turbine and a patty. Controls the amount of EGR gas that connects the exhaust passage between the curate filters to the engine intake passage downstream of the intake compressor of the exhaust turbocharger and the amount of EGR gas that is arranged in the EGR passage and recirculated from the exhaust passage into the engine intake passage. It is equipped with an EGR gas amount control device, and when the particulate filter is regenerated in a high engine load operation state, the Westgate valve device and the EGR gas amount control device are controlled to control the intake air in the engine intake passage. An exhaust gas purification device for an internal combustion engine that supplies a part to a particulate filter via an EGR passage is provided.

The particulate filter can be regenerated only by controlling the wastegate valve device and the EGR gas amount control device.

FIG. 1 is an overall view of an internal combustion engine. 2A and 2B are diagrams showing maps of iso-output lines and manifold pressures, respectively. 3A and 3B are diagrams showing the supercharging region and the intake compressor outlet pressure, respectively. FIG. 4 is a time chart of the particulate filter reproduction control. FIG. 5 is an explanatory diagram of a part of the time chart shown in FIG. FIG. 6 is a flowchart for performing reproduction control. FIG. 7 is a time chart of the particulate filter reproduction control in the second embodiment. FIG. 8 is a flowchart for performing reproduction control. FIG. 9 is a flowchart for performing reproduction control.

FIG. 1 shows an overall view of an internal combustion engine using gasoline as fuel. Referring to FIG. 1, 1 is an engine body, 2 is a combustion chamber of each cylinder, 3 is a fuel injection valve provided for each cylinder, 4 is an intake manifold, and 5 is an exhaust manifold. A throttle valve 6 driven by an actuator is arranged at the intake air inlet of the intake manifold 4. The intake manifold 4 is connected to the outlet of the intake compressor 8a of the exhaust turbocharger 8 via the intake duct 7, and the inlet of the intake compressor 8a is connected to the air cleaner 10 via the intake air amount detector 9. An intercooler 11 for cooling the intake air flowing in the intake duct 7 is arranged in the intake duct 7. On the other hand, the exhaust manifold 5 is connected to the inlet of the exhaust turbine 8b of the exhaust turbocharger 8 via the exhaust passage 12, and the outlet of the exhaust turbine 8b is connected to the exhaust passage 13.

An exhaust purification catalyst 14 is arranged in the exhaust passage 13, and a particulate filter (GPF) 13 is arranged in the exhaust passage 13 downstream of the catalyst 14. In the embodiment shown in FIG. 1, the catalyst 14 is composed of a three-way catalyst, and the three-way catalyst is supported on the particulate filter (GPF) 13. On the other hand, the exhaust passage 12 upstream of the exhaust turbine 8b is connected to the exhaust passage 13 between the exhaust turbine 8b and the catalyst 14 via the bypass passage 16 bypassing the exhaust turbine 8b, and the bypass passage 16 is inside the bypass passage 16. A wastegate valve device 17 including a wastegate valve that controls the amount of exhaust gas flowing through the inside is arranged. Further, the exhaust passage 13 between the catalyst 14 and the particulate filter 15 is connected to the intake manifold 4 via an exhaust gas recirculation (hereinafter referred to as EGR) passage 18, and an EGR valve is provided in the EGR passage 18. 19 is arranged. The EGR valve 19 forms an EGR gas amount control device that controls the amount of EGR gas recirculated from the exhaust passage 13 into the engine intake passage.

As shown in FIG. 1, a pressure sensor 20 for detecting the pressure in the intake manifold 4 (hereinafter referred to as the manifold pressure) is arranged in the intake manifold 4, and is located between the intake compressor 8a and the intercooler 11. In the intake duct 7 of the above, a pressure sensor 21 for detecting the intake air pressure at the outlet of the intake compressor 8a (hereinafter, referred to as the compressor outlet pressure) is arranged. Further, an air-fuel ratio sensor 22 is arranged in the exhaust passage 13 downstream of the catalyst 14. Further, the particulate filter 15 is provided with a differential pressure sensor 23 for detecting the differential pressure in the exhaust passage 13 before and after the particulate filter 15 and a temperature sensor 24 for detecting the temperature of the particulate filter 15. ing.

The electronic control unit 30 is composed of a digital computer, and is connected to each other by a bidirectional bus 31. A ROM (read-only memory) 32, a RAM (random access memory) 33, a CPU (microprocessor) 34, an input port 35, and an output port 36. Equipped with. The output signals of the intake air amount detector 9, the pressure sensor 20, the pressure sensor 21, the air fuel ratio sensor 22, the differential pressure sensor 23 and the temperature sensor 24 are input to the input port 35 via the corresponding AD converter 37. NS. Further, the accelerator pedal 40 is connected to an accelerator opening sensor 41 that generates an output voltage proportional to the depression amount of the accelerator pedal 40, that is, an accelerator opening degree, and the output voltage of the accelerator opening degree sensor 41 is a corresponding AD converter. It is input to the input port 35 via 37. Further, a crank angle sensor 42 that generates an output pulse every time the crankshaft rotates, for example, 30 ° is connected to the input port 35. In the CPU 34, the engine speed is calculated from the output pulse of the crank angle sensor 42. On the other hand, the output port 36 is connected to the fuel injection valve 3, the actuator for driving the throttle valve 6, the wastegate valve device 17, the EGR control valve 19, and the automatic transmission 25 attached to the engine body via the corresponding drive circuit 38. Will be done.

First, an outline of operation control during normal operation of the internal combustion engine shown in FIG. 1 will be described. In the internal combustion engine shown in FIG. 1, the air-fuel ratio is usually controlled to be the stoichiometric air-fuel ratio based on the output signal of the air-fuel ratio sensor 22, and therefore, unburned HC and CO contained in the exhaust gas. And NO _X are well purified in the catalyst 14, and unburned HC, CO and NO _X that could not be purified in the catalyst 14 are purified in the particulate filter 15 carrying the three-way catalyst. Further, the exhaust fine particles contained in the exhaust gas, that is, the particulate, are collected on the particulate filter 15. On the other hand, in the internal combustion engine shown in FIG. 1, the fuel supply is temporarily stopped during the vehicle deceleration operation. At this time, air is discharged from the engine, and this air is supplied to the particulate filter 15. As a result, the particulates deposited on the particulate filter 15 are burned and removed by this air, and the particulate filter 15 is regenerated.

The solid line in FIG. 2A shows the equal output line of the internal combustion engine shown in FIG. As shown in FIG. 2A, the engine output increases as the engine torque increases, and increases as the engine speed increases. In the internal combustion engine shown in FIG. 1, the air-fuel ratio is maintained at the stoichiometric air-fuel ratio as described above. Therefore, the isopower line shown by the solid line in FIG. 2A is supplied into the combustion chamber 2. It can be said that it shows the equal supply air amount line of air. Therefore, in FIG. 2A, when the required torque of the engine and the engine speed are determined, the amount of air supplied into the combustion chamber 2 is determined. On the other hand, the amount of EGR gas recirculated in the engine intake passage is determined when the engine torque and the engine speed are determined. Therefore, the manifold pressure when the amount of air supplied to the combustion chamber 2 is the amount of air determined by the required torque of the engine and the engine speed in the state where the EGR gas is recirculated is the engine pressure at this time. It becomes a constant value according to the required torque and engine speed. Further, the manifold pressure when the amount of air supplied to the combustion chamber 2 is the amount of air determined by the required torque of the engine and the engine rotation speed in the state where the recirculation of the EGR gas is stopped is also the engine pressure at this time. It becomes a constant value according to the required torque and engine speed. That is, the manifold pressure is determined when the required torque of the engine and the engine speed are determined. The manifold pressure Pij is stored in the ROM 33 in advance in the form of a map as shown in FIG. 2B as a function of the engine torque and the engine speed.

On the other hand, FIG. 3A shows an outline of control and supercharging control of the throttle valve 6 performed to obtain the amount of air supplied into the combustion chamber 2 shown in FIG. 2A. In FIG. 3A, the vertical axis represents the amount of air supplied into the combustion chamber 2, and the horizontal axis represents the engine speed. In FIG. 3A, the alternate long and short dash line M indicates the boundary between the supercharged region and the non-supercharged region. On this boundary M, the manifold pressure is approximately atmospheric pressure, and the region below the boundary M. Is not supercharged, and is supercharged in the region above the boundary M. Further, FIG. 3A shows the EGR upper limit and the EGR lower limit, and the EGR gas is recirculated in the region between the EGR upper limit and the EGR lower limit, and the region below the EGR lower limit and the EGR In the region above the upper limit, the recirculation of EGR gas is stopped. The EGR upper limit and the EGR lower limit shown in FIG. 3A are examples and differ depending on the type of engine and the like. In particular, the EGR upper limit shown in FIG. 3A also changes depending on factors other than the amount of air supplied to the combustion chamber 2 and the operating state of the engine other than the engine speed, for example, the engine cooling water temperature, and is shown in FIG. 3A. It is not fixed in the position where it is used. That is, the EGR upper limit in FIG. 3A is only shown at the position shown in FIG. 3A for convenience in explaining the invention.

Now, in FIG. 3A, in the non-supercharged region below the boundary M, the wastegate valve device 17 fully opens the bypass passage 16, and therefore, at this time, the exhaust turbocharger 8 is in an inactive state. .. Further, in the non-supercharged region below the boundary M, the amount of air supplied into the combustion chamber 2 is controlled by the throttle valve 6. On the other hand, in the supercharging region above the boundary M, the throttle valve 6 is fully opened, in the region below the EGR upper limit, EGR gas is recirculated, and in the region above the EGR upper limit. The recirculation of EGR gas has been stopped. Further, in this supercharging region, the wastegate valve of the wastegate valve device 17 is closed or partially opened, and the amount of air supplied into the combustion chamber 2 is the required torque of the engine shown in FIG. 2A. The boost pressure is controlled by the wastegate valve device 17 so that the amount of air is determined by the engine speed. At this time, the manifold pressure is the manifold pressure Pij shown in the map of FIG. 2B.

As described above, when the supply of fuel is temporarily stopped during the deceleration operation of the vehicle, the particulate filter 15 is regenerated. This vehicle deceleration operation is usually repeated frequently, and therefore, usually, the regeneration of the particulate filter 15 is performed without any problem. However, when the engine high load operation such as towing uphill continues, the particulate filter 15 is not regenerated because the vehicle deceleration operation is not performed. Therefore, in such a case, the particulate filter 15 is regenerated. When requested, the particulate filter 15 needs to be regenerated in some way. Therefore, in the present invention, in such a case, a part of the intake air is supplied to the particulate filter 15 through the EGR passage 18, thereby regenerating the particulate filter 15. In the embodiment according to the present invention, the regeneration control of the particulate filter 15 is performed when the operating state of the engine is in the supercharging region indicated by SS between the EGR upper limit and the full load line F in FIG. 3A. .. Hereinafter, the supercharging region in which the regeneration control of the particulate filter 15 according to the present invention is performed is referred to as a regeneration control region SS. As can be seen from FIG. 3A, the regeneration control region SS is an engine high load operation region.

Next, the outline of the reproduction control of the particulate filter 15 performed at this time will be described. When the accumulated amount of the particulates collected on the particulate filter 15 exceeds a certain amount, a request for regeneration of the particulate filter 15 is issued. Whether or not the accumulated amount of the particulate exceeds a certain amount is determined based on the calculated value of the accumulated amount of the particulate or the differential pressure before and after the particulate filter 15. In the embodiment according to the present invention, when the differential pressure before and after the particulate filter 15 exceeds the threshold value, it is determined that the particulate filter 15 should be regenerated, and a request for regeneration of the particulate filter 15 is issued.

When the particulate filter 15 should be regenerated, air is supplied to the particulate filter 15. When air is supplied to the particulate filter 15, the particulate deposited on the particulate filter 15 is oxidized and burned off from the particulate filter 15. In this case, the amount of air required per unit time when all the air supplied to the particulate filter 15 is consumed to burn and remove the particulate depends on the oxidation reaction rate of the particulate. The amount of air required per unit time for the combustion removal of the particulate filter increases as the temperature of the particulate filter 15 increases. In the embodiment according to the present invention, the air for burning and removing the particulate is supplied to the particulate filter 15 through the EGR passage 18. The amount of air required per unit time for burning and removing the particulate is hereinafter referred to as the required amount of air for regeneration tGegr.

As described above, in the embodiment according to the present invention, the regeneration control of the particulate filter 15 is performed when the operating state of the engine is in the regeneration control region SS shown in FIG. 3A, that is, the engine high load operating region. Will be done. In this regeneration control region SS, the EGR valve 19 is closed, and the recirculation of the EGR gas to the intake manifold 4 is stopped. Further, in the regeneration control region SS, the wastegate valve device 17 adjusts the WGV opening degree so that the amount of air supplied into the combustion chamber 2 becomes the amount of air determined from the required torque of the engine and the engine speed shown in FIG. 2A. (Wastegate valve opening) is controlled. As described above, the manifold pressure at this time is the manifold pressure Pij shown in the map of FIG. 2B.

By the way, in the embodiment according to the present invention, when the regeneration request of the particulate filter 15 is made when the operating state of the engine is the regeneration control region SS, a part of the intake air is partitioned through the EGR passage 18. The EGR valve 19 is opened to supply to 15, and at this time, the amount of air Gegr supplied to the particulate filter 15 via the EGR passage 18 becomes the required amount of air tGegr for regeneration. The WGV opening degree is controlled by the wastegate valve device 17, and the opening degree of the EGR valve 19 is controlled. Next, the reproduction control of the particulate filter 15 will be described with reference to the time chart shown in FIG.

Referring to FIG. 4, FIG. 4 shows the vehicle speed, the amount of depression of the accelerator pedal 40 (accelerator opening), the engine torque, and the pressure (compressor outlet pressure Pc) from the end of the accelerated operation to the stabilization of the engine operation. The changes over time of the manifold pressure Pm), the WGV opening degree (wastegate valve opening degree), the amount of air supplied to the particulate filter 15 via the EGR passage 18, and the EGR valve opening degree are shown. Referring to FIG. 4, when the amount of depression of the accelerator pedal 40 is gradually reduced at the end of the accelerated operation, the engine torque is also gradually reduced. At this time, the WGV opening degree is also gradually reduced. When the WGV opening degree is decreased, the boost pressure is increased, so that the compressor outlet pressure Pc and the manifold pressure Pm increase. As shown in FIG. 4, the manifold pressure Pm is lower than the compressor outlet pressure Pc by the amount of pressure decrease when the intake air flows through the intercooler 11.

When the acceleration operation is completed and the substantially steady engine operation state continues for a certain period of time, the regeneration control of the particulate filter 15 is performed for the period indicated by the GPF regeneration during firing in FIG. When the particulate filter 15 is regenerated, the required air amount tGegr for regeneration is calculated based on the temperature of the particulate filter 15, and the manifold pressure Pm is operated by the engine so that the output of the engine does not change. While maintaining the manifold pressure Pij shown in FIG. 2B according to the state, the WGV opening degree is gradually reduced so that the amount of air supplied to the particulate filter 15 Gegr becomes the required amount of air tGegr for regeneration. The compressor outlet pressure Pc is gradually increased to the target compressor outlet pressure tPc, and the EGR valve 19 is gradually opened. When the EGR valve 19 is opened, a part of the intake air is supplied to the particulate filter 15 through the EGR passage 18, and the combustion removing action of the particulate deposited on the particulate filter 15 is performed. In this case, since the air supplied to the particulate filter 15 is consumed to burn and remove the particulate, the gas flowing at least in the downstream portion of the particulate filter 15 has a substantially stoichiometric air-fuel ratio. Therefore, even during the regeneration of the particulate filter 15, the unburned HC, CO, and NO _X in the exhaust gas are purified by the particulate filter 15 carrying the three-way catalyst.

Here, the target compressor outlet pressure tPc described above will be described with reference to FIG. 3B. The horizontal axis of FIG. 3B shows the intake air amount QA flowing into the intake manifold 4 through the intercooler 11, and the vertical axis of FIG. 3B is the manifold pressure Pm and the compressor outlet pressure Pc based on the manifold pressure Pm. The pressure difference ΔP with and from is shown. As the intake air amount QA increases, the pressure drop in the intercooler 11 increases. Therefore, as shown by the solid line in FIG. 3B, as the intake air amount QA increases, the pressure difference ΔP between the manifold pressure Pm and the compressor outlet pressure Pc increases. growing. In FIG. 3B, QAo represents the amount of intake air supplied into the combustion chamber 2 when the manifold pressure Pm is the manifold pressure Pij corresponding to the operating state of the engine shown by the broken line in FIG. ΔP ₀ indicates the pressure difference ΔP between the manifold pressure Pm and the compressor outlet pressure Pc at this time. The amount of intake air flowing into the intake manifold 4 through the intercooler 11 is used for regeneration without changing the amount of intake air QAo supplied into the combustion chamber 2, in other words, without changing the manifold pressure Pij. If the required air amount tGegr is increased, air is supplied to the particulate filter 15 through the EGR passage 18 by the increased air amount. Therefore, if the intake air amount QA flowing into the intake manifold 4 through the intercooler 11 is increased by the required air amount tGegr for regeneration without changing the manifold pressure Pij, it is supplied to the particulate filter 15. The amount of air Gegr can be set to the required amount of air tGegr for regeneration.

As can be seen from FIG. 3B, in order to increase the intake air amount supplied into the intake manifold 4 by the required air amount tGegr for regeneration, the pressure difference ΔP between the manifold pressure Pm and the compressor outlet pressure Pc is increased to ΔPt. Therefore, in the embodiment according to the present invention, a pressure higher than the manifold pressure Pij according to the operating state of the engine by a pressure difference ΔPt is set as the target compressor outlet pressure tPc, and the manifold pressure Pij is changed. The WGV opening degree is controlled by the Westgate valve device 17 and the opening degree of the EGR valve 19 is controlled so that the compressor outlet pressure Pc becomes the target compressor outlet pressure tPc. In this case, in reality, the target compressor outlet pressure tPc is obtained from, for example, the compressor outlet pressure Pc (Pm + ΔPo) according to the operating state of the engine detected by the pressure sensor 21 from the required air amount tGegr for regeneration. It is calculated by adding the differential pressure (ΔPt—ΔPo) (FIG. 3B). The relationship between the intake air amount QA and the pressure difference ΔP shown by the solid line in FIG. 3B differs depending on the manifold pressure Pm, and in the embodiment according to the present invention, the intake air amount QA and the pressure difference ΔP with respect to the typical manifold pressure Pm. The relationship with is stored in the ROM 33 in advance.

5, the compressor outlet pressure Pc, manifold pressure Pm at time _{t 0} in FIG. 4, WGV opening (waste gate valve opening), is supplied to the particulate filter 15 via the EGR valve opening degree and the EGR passage 18, The temporal change of the air volume Gegr is schematically shown. Note that FIG. 5 also shows the target compressor outlet pressure tPc and the required air amount tGegr for regeneration. When the compressor outlet pressure Pc is raised to the target compressor outlet pressure tPc, as shown in FIG. 5, the WGV opening degree is reduced by a small constant amount. When the WGV opening degree is lowered, the compressor outlet pressure Pc rises a little and the manifold pressure Pm rises a little. When the manifold pressure Pm increases, the EGR valve opening degree is increased until the manifold pressure Pm decreases to the original pressure. When the EGR valve opening degree is increased, the amount of air Gegr supplied to the particulate filter 15 is increased. Then, again, the WGV opening degree is reduced by a small constant amount, so that when the manifold pressure Pm rises a little, the EGR valve opening degree is increased until the manifold pressure Pm drops to the original pressure.

Such an action of lowering the WGV opening degree and an action of increasing the EGR valve opening degree are repeated until the compressor outlet pressure Pc reaches the target compressor outlet pressure tPc. When the compressor outlet pressure Pc reaches the target compressor outlet pressure tPc, the air amount Gegr supplied to the particulate filter 15 becomes the required air amount tGegr for regeneration. Since the temperature of the particulate filter 15 changes while the action of lowering the WGV opening degree and the action of increasing the EGR valve opening degree are performed, the required air amount tGegr for regeneration also changes. Therefore, the target compressor outlet pressure tPc continues to be updated while the regeneration control of the particulate filter 15 is being performed. When the regeneration action of the particulate filter 15 is completed, the action of increasing the WGV opening degree and the action of lowering the EGR valve opening degree are performed by the same method until the compressor outlet pressure Pc becomes the original compressor outlet pressure Pc. It is repeated.

Next, the reproduction control of the particulate filter will be described with reference to FIG. FIG. 6 shows a routine for executing this reproduction control, and this routine is executed, for example, by an interrupt at regular time intervals.

With reference to FIG. 6, first, in step 50, it is determined whether or not a reproduction flag indicating that the particulate filter 15 should be reproduced is set. When the reproduction flag is not set, the process proceeds to step 51 to determine whether or not the particulate filter 15 needs to be reproduced. In the embodiment according to the present invention, when it is determined from the output signal of the differential pressure sensor 23 that the front-rear differential pressure of the particulate filter 15 exceeds the threshold value, it is determined that the particulate filter 15 needs to be regenerated. When it is determined in step 51 that regeneration of the particulate filter 15 is not necessary, the process proceeds to step 59 to perform normal control of the WGV (wastegate valve) and normal control of the EGR valve, that is, normal boost pressure control. Normal EGR control is performed.

On the other hand, when it is determined in step 51 that the particulate filter 15 needs to be regenerated, the process proceeds to step 52, the reproduction flag is set, and then the process proceeds to step 53. Once the playback flag is set, the next processing cycle jumps from step 50 to step 53. In step 53, it is determined whether or not the reproduction condition of the particulate filter 15 is satisfied. In the embodiment according to the present invention, when it is determined that the following three conditions are satisfied based on the output signal of the accelerator opening sensor 41, it is determined that the reproduction condition is satisfied.
(1) Accelerator opening> Regeneration execution transition threshold (2) Upper limit threshold> Accelerator opening time change rate> Lower limit threshold (3) Duration of the states of (1) and (2)> Regeneration execution transition threshold That is, the engine It is determined that the regeneration condition is satisfied when the operating state is the regeneration control region SS, that is, the period in which the engine load is high and the fluctuation amount of the engine load is small continues for a certain period or more.

When it is determined in step 53 that the regeneration conditions are not satisfied, the process proceeds to step 59, and normal boost pressure control and normal EGR control are performed. On the other hand, when it is determined in step 53 that the regeneration condition is satisfied, the process proceeds to step 54, and the temperature TG of the particulate filter 15 is acquired. In the embodiment according to the present invention, the temperature TG of the particulate filter 15 is acquired by the temperature sensor 24. Next, in step 55, the required air amount tGegr for regeneration is calculated based on the temperature of the particulate filter 15. Further, in step 55, the differential pressure (ΔPt—ΔPo) (FIG. 3B) obtained from the required air amount tGegr for regeneration is applied to the compressor outlet pressure Pc according to the operating state of the engine detected by the pressure sensor 21. By adding, the target compressor outlet pressure tPc is calculated.

Next, in step 56, based on the output signals of the pressure sensor 20 and the pressure sensor 21, the compressor outlet pressure Pc becomes the target compressor outlet pressure tPc by the method described with reference to FIG. 5 without changing the manifold pressure Pm. The WGV opening degree is controlled by the Westgate valve device 17 and the opening degree of the EGR valve 19 is controlled so as to be. Next, in step 57, it is determined whether or not the regeneration of the particulate filter 15 is completed. In the embodiment according to the present invention, when it is determined from the output signal of the differential pressure sensor 23 that the front-rear differential pressure of the particulate filter 15 becomes a small constant value or less, it is determined that the regeneration of the particulate filter 15 is completed. In step 57, when it is determined that the reproduction of the particulate filter 15 is not completed, the processing cycle is terminated, and when it is determined that the reproduction of the particulate filter 15 is completed, the process proceeds to step 58 to reset the reproduction flag. Then, the processing cycle is terminated.

A second embodiment is shown in FIGS. 7 to 9. When the partial filter 15 is requested to be regenerated, the operating state of the engine is in the regeneration control region SS shown in FIG. 3A, that is, the engine high load operating region, but the manifold pressure Pm is low at this time, and the patty at this time. If the manifold pressure Pm is lower than the pressure at the inlet of the curate filter 15, a part of the intake air cannot be supplied to the particulate filter 15 through the EGR passage 18. In this second embodiment, the operating state of the engine is changed to the low rotation speed and high torque side so that a part of the intake air can be supplied to the particulate filter 15 through the EGR passage 18 even in such a case. By increasing the boost pressure, the manifold pressure Pm is increased so that the particulate filter 15 can be regenerated by the regeneration method according to the present invention. In this case, in this second embodiment, the operating state of the engine is changed to the low rotation speed and high torque side by shifting up the speed change stage of the automatic transmission 25 from a low stage position to a high stage position. Next, the reproduction control of the particulate filter 15 according to the second embodiment will be described with reference to the time chart shown in FIG. 7.

Referring to FIG. 7, FIG. 7 shows the vehicle speed, the amount of depression of the accelerator pedal 40 (accelerator opening), the engine torque, and the pressure during the period from the end of the accelerated operation to the stabilization of the engine operation, as in FIG. (Compressor outlet pressure Pc and manifold pressure Pm), WGV opening (wastegate valve opening), amount of air supplied to the particulate filter 15 via the EGR passage 18, Gegr, and EGR valve opening over time. The time change of the gear stage and the engine speed of the automatic transmission 25 is shown. Further, FIG. 7 shows a case where the particulate filter 15 is requested to be regenerated while the engine is being operated in the regeneration control region SS shown in FIG. 3A, that is, the engine high load operation region.

Referring to FIG. 7, when the acceleration operation is completed and the almost steady engine operation state continues for a certain period of time, the gear stage shift-up action of the automatic transmission 25 is performed during the period shown by the shift in FIG. As a result, the boost pressure is increased and the manifold pressure Pm is increased. When the manifold pressure Pm is increased, the regeneration control of the particulate filter 15 is performed during the period shown in the GPF regeneration during firing in FIG. 7, as in the first embodiment shown in FIG. When the particulate filter 15 is regenerated, the required air amount tGegr for regeneration is calculated based on the temperature of the particulate filter 15, and the manifold pressure Pm is operated by the engine so that the output of the engine does not change. While maintaining the manifold pressure Pij shown in FIG. 2B according to the state, the WGV opening degree is gradually reduced so that the amount of air supplied to the particulate filter 15 Gegr becomes the required amount of air tGegr for regeneration. The compressor outlet pressure Pc is gradually increased to the target compressor outlet pressure tPc, and the EGR valve 19 is gradually opened.

When the EGR valve 19 is opened, a part of the intake air is supplied to the particulate filter 15 through the EGR passage 18, and the combustion removing action of the particulate deposited on the particulate filter 15 is performed. When the regeneration of the particulate filter 15 is completed, the shift-down action of the gear stage of the automatic transmission 25 is performed in the period shown by the shift in FIG. 7, and the engine is again in the operating state before the regeneration control. It will be driven with.

Next, the reproduction control of the particulate filter in the second embodiment will be described with reference to FIGS. 8 and 9. 8 and 9 show a routine for executing the reproduction control in the second embodiment, and this routine is executed, for example, by an interrupt at regular time intervals.

With reference to FIGS. 8 and 9, first of all, in step 80, it is determined whether or not a reproduction flag indicating that the particulate filter 15 should be reproduced is set. When the reproduction flag is not set, the process proceeds to step 81, and it is determined whether or not the particulate filter 15 needs to be reproduced. Also in this second embodiment, when it is determined from the output signal of the differential pressure sensor 23 that the front-rear differential pressure of the particulate filter 15 exceeds the threshold value, it is determined that the particulate filter 15 needs to be regenerated. When it is determined in step 81 that the regeneration of the particulate filter 15 is not necessary, the process proceeds to step 93, and the normal control of the WGV (wastegate valve), the normal control of the EGR valve, and the normal control of the transmission, that is, the normal control Supercharging pressure control, normal EGR control, and normal automatic shift control are performed.

On the other hand, when it is determined in step 81 that the particulate filter 15 needs to be regenerated, the process proceeds to step 82, the reproduction flag is set, and then the process proceeds to step 83. Once the playback flag is set, the next processing cycle jumps from step 80 to step 83. In step 83, it is determined whether or not the reproduction condition of the particulate filter 15 is satisfied. Also in this second embodiment, as in the first embodiment shown in FIG. 4, when it is determined that the following three conditions are satisfied based on the output signal of the accelerator opening sensor 41, the reproduction condition Is determined to satisfy.
(1) Accelerator opening> Regeneration execution transition threshold (2) Upper limit threshold> Accelerator opening time change rate> Lower limit threshold (3) Duration of the states of (1) and (2)> Regeneration execution transition threshold That is, the engine It is determined that the regeneration condition is satisfied when the operating state is the regeneration control region SS, that is, the period in which the engine load is high and the fluctuation amount of the engine load is small continues for a certain period or more.

When it is determined in step 83 that the reproduction condition is not satisfied, the process proceeds to step 93, and normal boost pressure control, normal EGR control, and normal automatic shift control are performed. On the other hand, when it is determined in step 83 that the regeneration condition is satisfied, the process proceeds to step 84, and the manifold pressure Pm is particulateized using the regeneration method according to the present invention based on the output signal of the pressure sensor 20. It is determined whether the filter 15 is higher than the manifold pressure PmX that can be regenerated. When it is determined that the manifold pressure Pm is higher than the manifold pressure PmX, the process proceeds to step 85, and the temperature TG of the particulate filter 15 is acquired. Also in this second embodiment, the temperature TG of the particulate filter 15 is acquired by the temperature sensor 24 as in the first embodiment shown in FIG. Next, in step 86, the required air amount tGegr for regeneration is calculated based on the temperature of the particulate filter 15. Further, in step 86, the differential pressure (ΔPt—ΔPo) (FIG. 3B) obtained from the required air amount tGegr for regeneration is applied to the compressor outlet pressure Pc according to the operating state of the engine detected by the pressure sensor 21. By adding, the target compressor outlet pressure tPc is calculated.

Next, in step 87, based on the output signals of the pressure sensor 20 and the pressure sensor 21, the compressor outlet pressure Pc becomes the target compressor outlet pressure tPc by the method described with reference to FIG. 5 without changing the manifold pressure Pm. The WGV opening degree is controlled by the Westgate valve device 17 and the opening degree of the EGR valve 19 is controlled so as to be. Next, in step 88, it is determined whether or not the regeneration of the particulate filter 15 is completed. Also in this second embodiment, when it is determined from the output signal of the differential pressure sensor 23 that the front-rear differential pressure of the particulate filter 15 becomes a small constant value or less, it is determined that the regeneration of the particulate filter 15 is completed. In step 88, when it is determined that the reproduction of the particulate filter 15 is not completed, the processing cycle is terminated, and when it is determined that the reproduction of the particulate filter 15 is completed, the process proceeds to step 89 and the reproduction flag is reset. Then, the processing cycle is terminated.

On the other hand, in step 84, when the manifold pressure Pm is determined to not higher than the manifold pressure PmX, the process proceeds to step 90, the current gear position S ₀ of the automatic transmission 25, using the reproduction method according to the invention The target gear stage S required to regenerate the particulate filter 15 is required. Next, in step 91, _{it is determined whether or not the current gear stage S 0} has become the target gear stage S. When it is determined that the current gear stage S ₀ is not the target gear stage S, the process proceeds to step 92, and the current gear stage S ₀ is shifted up by one stage. Then, the processing cycle is terminated. On the other hand, in step 91, _{when it is determined that the current gear stage S 0} has reached the target gear stage S, the processing cycle is terminated.

As described above, according to the present invention, the exhaust turbocharger 8 for supercharging is provided, and the exhaust turbine 8b of the exhaust turbocharger 8 is arranged in the engine exhaust passage, bypassing the exhaust turbine 8b. A bypass passage 16 that connects the exhaust passage 12 upstream of the exhaust turbine 8b and the exhaust passage 13 downstream of the exhaust turbine 8b, a waistgate valve device 17 that controls the amount of exhaust gas flowing in the bypass passage 16, and a downstream of the exhaust turbine 8b. The exhaust passage 15 arranged in the exhaust passage, the EGR passage 18 connecting the exhaust passage 13 between the exhaust turbine 8b and the particulate filter 15 to the engine intake passage downstream of the intake compressor 8a of the exhaust turbocharger 8, and the EGR passage. It is provided with an EGR gas amount control device which is arranged in 18 and controls the amount of EGR gas recirculated from the exhaust passage 13 into the engine intake passage, and can regenerate the particulate filter 15 in an engine high load operation state. At that time, a part of the intake air in the engine intake passage is supplied to the particulate filter 15 through the EGR passage 18 by controlling the Westgate valve device 17 and the EGR gas amount control device.

4 Intake manifold 5 Exhaust manifold 8 Exhaust turbocharger 15 Particulate filter 17 Wastegate valve device 18 EGR control valve

Claims (1)

Equipped with an exhaust turbocharger for supercharging, the exhaust turbine of the exhaust turbocharger is arranged in the engine exhaust passage, bypassing the exhaust turbine, and the exhaust passage upstream of the exhaust turbine and the exhaust passage downstream of the exhaust turbine. A bypass passage connecting the two, a waistgate valve device that controls the amount of exhaust gas flowing in the bypass passage, a particulate filter arranged in the exhaust passage downstream of the exhaust turbine, and an exhaust passage between the exhaust turbine and the particulate filter. An EGR passage that connects the exhaust gas to the engine intake passage downstream of the intake compressor of the exhaust turbocharger, and an EGR gas amount control device that is arranged in the EGR passage and controls the amount of EGR gas that is recirculated from the exhaust passage into the engine intake passage. When the particulate filter is regenerated in a high engine load operation state, the Westgate valve device and the EGR gas amount control device are controlled so that a part of the intake air in the engine intake passage is used in the EGR passage. An exhaust gas purification device for an internal combustion engine that supplies a particulate filter through an exhaust gas.

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