JP2009287515A - Controller of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller of an internal combustion engine for enabling removal of particulate material accumulated on an end face on an upstream side of an exhaust emission control device without causing deterioration in operability when a requested load is increased. <P>SOLUTION: During the implementation of fuel cut (step S12) with a revolution speed NE allowed to be larger than a PM removing revolution speed NE2 faster (step S11) than a fuel cut revolution speed, being lower limit of a revolution speed intended for discriminating a decelerating running state, an EGR valve 15 is allowed to transfer to a fully-closed state and besides a throttle valve 16 is allowed to transfer to a fully-open state (step S13). As a result, an intake airflow gets larger to increase an exhaust airflow, which swiftly inflows into the exhaust emission control system. Accordingly, the exhaust airflow is allowed to swiftly blow to the end face of the upstream side of the exhaust emission control system, thus removing the PM accumulated on the end face. Besides, by performing this action during the implementation of fuel cut at the time of no running request from a driver, the running performance deterioration can be avoided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine including an exhaust purification device.

  An exhaust purification device for purifying exhaust gas is provided in an exhaust passage of an internal combustion engine such as a diesel engine for vehicles. This exhaust purification device includes a catalytic converter carrying an NOx storage reduction catalyst for purifying nitrogen oxides (NOx), a filter for collecting particulate matter in the exhaust gas downstream of the catalyst, etc. Is installed.

  In such an exhaust purification device, in order to suppress the deterioration of the filter, a so-called function regeneration process is performed to periodically remove particulate matter adhering to the filter. This function regeneration processing is performed by supplying, for example, exhaust gas containing unburned fuel components to an exhaust gas purification device, and heating the filter with the oxidation heat of the unburned fuel components, thereby adhering particulate matter to the filter. Is oxidized and removed. On the other hand, in the catalyst disposed on the upstream side of the filter, even when the function regeneration process is performed, the temperature of the upstream end surface is difficult to raise, so the fine particles accumulated on the upstream end surface There has been a problem that the particulate matter is not sufficiently removed. Further, when the unburned fuel component is supplied to the exhaust purification device to obtain the oxidation heat, the unburned fuel component adheres to the upstream end face of the catalyst, and the unburned fuel component and the fine particles contained in the exhaust gas As a result, the particulate matter is likely to be deposited on the end face on the upstream side of the catalyst.

Therefore, in order to remove the particulate matter deposited on the upstream end face, in the exhaust system of Patent Document 1, a bypass pipe that connects the upstream portion and the downstream portion sandwiching the turbine of the turbocharger is provided. Provided, the exhaust from the bypass pipe is blown along the surface direction against the end face on the upstream side of the catalyst. As a result, every time particulate matter deposited on the upstream end face of the catalyst is exhausted from the bypass pipe, it is removed from the catalyst and blown off to a filter downstream of the catalyst.
Japanese Patent Laid-Open No. 2006-9663

  On the other hand, in Patent Document 1, since a part of the exhaust from the combustion chamber is sent to the bypass pipe, the amount of exhaust sent to the turbocharger turbine is reduced by the amount of exhaust flowing through the bypass pipe, and finally supplied to the combustion chamber. This will reduce the supercharging pressure of the intake air. For this reason, the supercharging pressure corresponding to the required load of the internal combustion engine cannot be obtained, so that it becomes difficult to realize the engine operation corresponding to the required load, which leads to a decrease in operability related to the required load. With respect to this problem, Patent Document 1 detects the amount of particulate matter deposited on the end face of the catalyst and sends exhaust to the bypass pipe only when the detection result exceeds the specified amount of deposition. As long as it is sent to the bypass pipe, it is difficult to avoid the influence on the drivability described above, and even if the particulate matter can be removed, a new problem of reduced drivability is caused.

  The present invention has been made in view of the above-mentioned problems, and the object of the present invention is to reduce the amount of particulate matter deposited on the upstream end face of the exhaust emission control device without causing a decrease in operability with respect to an increase in required load. An object of the present invention is to provide a control device for an internal combustion engine that enables removal.

The control apparatus for an internal combustion engine according to claim 1 includes an exhaust purification catalyst for purifying exhaust gas from the internal combustion engine and a collector in an aspect having the exhaust purification apparatus provided in the exhaust system of the internal combustion engine from upstream. An EGR valve that allows a part of the exhaust gas to recirculate to the intake system of the internal combustion engine as EGR gas, and a throttle valve provided in the intake system have an EGR rate set to a target value corresponding to the operating state of the internal combustion engine EGR control means for controlling opening and closing, and fuel cut means for determining whether or not a fuel cut condition is satisfied based on the operating state of the internal combustion engine and controlling fuel cut based on the determination result A control device for an internal combustion engine, wherein when the rotational speed of the internal combustion engine is equal to or greater than a threshold value and the fuel cut condition is satisfied, the fuel cut means performs the fuel cut while performing the fuel cut. The control means opens the throttle valve to a predetermined position, and the gist of closing the EGR valve to a predetermined position.

  According to this invention, when the rotational speed is equal to or higher than the threshold value and the fuel cut is executed, the EGR valve is closed to a predetermined position and the throttle valve is opened to a predetermined position. For example, a deceleration operation fuel cut executed when the driver does not operate the accelerator pedal, an overspeed fuel cut executed when the rotation speed exceeds a predetermined upper limit value, or when the temperature of the exhaust purification catalyst exceeds a predetermined upper limit value When the catalyst heating fuel cut to be executed is being executed, the EGR valve is closed to a predetermined position, and the throttle valve is opened to a predetermined position. Thus, by reducing the EGR gas amount from that during normal operation, a large amount of intake air amount corresponding to the rotational speed threshold is sucked into the combustion chamber while suppressing exhaust gas recirculation. Increased exhaust gas is blown vigorously on the upstream end face. As a result, the particulate matter deposited on the end face of the exhaust purification device can be removed along with the flow of the exhaust. In addition, when the fuel cut is executed, there is no required load on the internal combustion engine. Therefore, when the EGR valve closing control and the throttle valve opening control are executed, the drivability decreases with increasing required load. Will not be invited.

The control apparatus for an internal combustion engine according to claim 2, wherein, when the rotation speed of the internal combustion engine is equal to or higher than a threshold value and the fuel cut condition is satisfied, the fuel cut means performs the fuel cut while performing the fuel cut. The gist of the invention is that the throttle valve is fully opened by the control means and the EGR valve is fully closed.
According to the present invention, when the rotational speed is equal to or higher than the threshold value and the fuel cut is executed, the EGR valve is fully closed and the throttle valve is fully open. Therefore, a large amount of intake air corresponding to the rotational speed threshold is sucked into the combustion chamber while exhaust gas recirculation is stopped, so that the increased amount of exhaust gas is more vigorous on the upstream end face of the exhaust purification device. Be sprayed. As a result, the particulate matter deposited on the end face of the exhaust purification device can be surely removed along with the flow of the exhaust.
The control apparatus for an internal combustion engine according to claim 3 is characterized in that the fuel cut condition is a deceleration fuel cut condition.

  According to the present invention, the EGR valve closing control and the throttle valve opening control are executed at the time of deceleration fuel cut. As a result, a large amount of exhaust gas corresponding to a high rotational speed can be vigorously sprayed toward the upstream end face of the exhaust purification apparatus, and therefore the particulate matter deposited on the upstream end face of the exhaust purification apparatus is more effective. Can be removed.

The gist of the control device for an internal combustion engine according to claim 4 is that a threshold value of the rotational speed is higher than a lower limit value of the rotational speed in the deceleration fuel cut condition.
According to the present invention, the above-described throttle valve opening control and EGR valve closing control are executed only in the operating region where the rotational speed is high while the deceleration fuel cut condition is satisfied. As a result, the removal process of the particulate matter can be executed only when a large amount of exhaust gas can be obtained, and therefore, it is possible to avoid excessive blowing of exhaust gas to the upstream end face of the exhaust gas purification device. When performing the removal process, it is possible to suppress an excessive temperature drop of the exhaust purification catalyst, that is, a reduction in purification ability.

  The internal combustion engine control device according to claim 5 is the internal combustion engine control device according to any one of claims 1 to 3, further comprising temperature detection means for detecting a temperature of the exhaust purification catalyst, When the rotational speed of the internal combustion engine is equal to or higher than the threshold value and the temperature of the exhaust purification catalyst is equal to or lower than the threshold value from the state where the fuel cut condition is satisfied, the throttle valve is opened so that the EGR rate becomes the target value. The gist is to change the degree and the opening degree of the EGR valve.

  According to the present invention, when the temperature of the exhaust purification catalyst in the exhaust purification device becomes equal to or lower than the threshold value due to the exhaust emission to the exhaust purification device, the increased exhaust emission is stopped. As a result, an excessive temperature drop of the exhaust purification catalyst, that is, a reduction in purification capability, can be suppressed in executing the particulate matter removal process.

  The control device for an internal combustion engine according to claim 6 is the control device for an internal combustion engine according to any one of claims 1 to 4, wherein an additive for recovering the purification ability of the exhaust purification device is added to the exhaust purification device. An addition control means for adding to the exhaust gas purification apparatus, wherein the throttle valve is opened to a predetermined position, and after the EGR valve is closed to a predetermined position, the addition control means adds the additive to the exhaust purification device. And

  According to the present invention, it is possible to recover the purification ability of the exhaust purification device after removing the particulate matter from the end face of the exhaust purification catalyst, so that the purification ability can be recovered more effectively.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic diagram showing a diesel engine 1 as an internal combustion engine and its peripheral configuration.
As shown in FIG. 1, the diesel engine 1 is provided with a plurality of cylinders # 1, # 2, # 3, and # 4, and a cylinder head 2 is provided so as to cover each cylinder # 1 to # 4. Fuel injection valves 4a, 4b, 4c, and 4d for injecting fuel into the cylinders # 1 to # 4 are attached to the cylinder head 2. The fuel injection valves 4a to 4d inject fuel at a fuel injection timing and an injection time corresponding to the rotation of a crankshaft (not shown). The fuel injection valves 4a to 4d are respectively connected to a common rail 9 that accumulates high-pressure fuel. The common rail 9 is connected to the supply pump 10. The supply pump 10 sucks the fuel in the fuel tank and supplies the fuel to the common rail 9 at a high pressure. The high-pressure fuel supplied to the common rail 9 is injected into the corresponding cylinder from the fuel injection valves 4a to 4d when the fuel injection valves 4a to 4d are opened.

  The cylinder head 2 is provided with an intake port for introducing intake air into each cylinder # 1 to # 4 for each cylinder. The cylinder head 2 is provided with an intake valve (not shown) that opens and closes each intake port. The intake valve opens at a predetermined valve opening timing and valve opening time according to the rotation of a crankshaft (not shown), thereby introducing intake air into each cylinder # 1 to # 4.

  An intake manifold 7 communicating with the intake passage 3 is connected to the intake port. A throttle valve 16 for adjusting the amount of intake air introduced into each cylinder # 1 to # 4 is provided in the intake passage 3. The throttle valve 16 is an electric type that is opened and closed by an actuator 17 and adjusts the amount of intake air introduced into each cylinder # 1 to # 4 by opening the valve at a predetermined throttle opening. Note that the intake system in the present embodiment includes the intake passage 3 and the intake manifold 7.

The cylinder head 2 is provided with exhaust ports 6a, 6b, 6c, 6d for discharging combustion gas to the outside of the cylinders corresponding to the cylinders # 1 to # 4. The cylinder head 2 is provided with an exhaust valve (not shown) that opens and closes the exhaust ports 6a to 6d. The exhaust valve opens at a predetermined valve opening timing and valve opening time according to the rotation of a crankshaft (not shown), and discharges combustion gas outside the cylinder.

  An exhaust manifold 8 communicating with the exhaust passage 26 is connected to the exhaust ports 6a to 6d. A turbocharger 11 is disposed in the middle of the exhaust passage 26, and an exhaust purification device 30 is disposed downstream of the turbocharger 11.

  The turbocharger 11 is a device that supercharges the intake air introduced into the cylinders # 1 to # 4 using the exhaust gas that passes through the exhaust passage 26. The turbocharger 11 includes a turbine 11a provided in the exhaust passage 26, and a compressor 11b provided in the intake passage 3 and interlocked with the turbine 11a. The turbocharger 11 drives the turbine 11a and the compressor 11b using exhaust gas, and supercharges intake air by cooperating them. The superheated intake air whose temperature has risen is cooled by an intercooler 18 provided in the intake passage 3 between the compressor 11 b and the throttle valve 16.

The exhaust purification device 30 is a device that purifies exhaust components from the cylinders # 1 to # 4. The exhaust purification device 30 is provided with a NOx storage reduction catalyst 31 and a filter 32 as a collector in order from the upstream side. The NOx occlusion reduction catalyst 31 occludes NOx in the exhaust in the lean state, while in the rich state, the occluded NOx, carbon monoxide (CO) contained in the exhaust, and hydrocarbons (HC) of unburned fuel components. To reduce NOx and purify the exhaust gas by using nitrogen (N ₂ ), carbon dioxide (CO ₂ ), and water (H ₂ O). The filter 32 is composed of a porous ceramic structure on which HC in the exhaust gas, that is, a catalyst for oxidizing the unburned fuel component, is supported, and captures particulate matter (PM) contained in the exhaust gas. It is a member to collect. The filter 32 oxidizes and removes the collected PM using heat of oxidation when the supported oxidation catalyst oxidizes the unburned fuel component.

  The cylinder head 2 is provided with an additive injection valve 5 for supplying unburned fuel as an additive to the exhaust purification device 30. The additive injection valve 5 is connected to the supply pump 10 via a fuel supply pipe 27, and unburned fuel is injected from the additive injection valve 5 into the exhaust port 6d of the cylinder # 4. The The injected unburned fuel reaches the exhaust gas purification device 30 together with the exhaust gas, reduces NOx by the NOx occlusion reduction catalyst 31, and is oxidized by the oxidation catalyst carried on the filter 32 to increase the temperature of the filter 32. . The additive injection valve 5 has the same structure as the fuel injection valves 4a to 4d. Further, the arrangement position of the additive injection valve 5 may be appropriately changed as long as it is in the exhaust system and upstream of the exhaust purification device 30.

  In addition, the diesel engine 1 is provided with an exhaust gas recirculation device (EGR device: Exhaust Gas Recirculation device). This EGR device is a device that reduces the amount of NOx generated by lowering the combustion temperature in the cylinder by introducing part of the exhaust gas into the intake air. The EGR device includes an EGR passage 13 that connects the downstream of the throttle valve 16 in the intake passage 3 and the upstream of the turbine 11 a in the exhaust passage 26, an EGR valve 15 provided in the middle of the EGR passage 13, and the EGR passage 13. It is comprised by the EGR cooler 14 etc. which were provided in the middle. The EGR valve 15 adjusts the exhaust amount, that is, the EGR amount introduced from the exhaust manifold 8 (exhaust system) to the intake manifold 7 (intake system) by changing the opening degree. Further, the EGR cooler 14 lowers the temperature of the EGR gas flowing through the EGR passage 13.

Such various controls of the diesel engine 1 are performed by an electronic control device 25 mounted on the vehicle. The electronic control unit 25 includes a calculation unit that executes calculation processing for various controls of the diesel engine 1, a storage unit that temporarily stores programs and data necessary for various controls, and calculation results of the calculation unit. And an input port and an output port for inputting / outputting signals to / from the outside.

  Detection signals from various sensors are input to the input port of the electronic control unit 25 in order to grasp the operating state of the diesel engine 1 and the like. Specifically, a detection signal related to the intake air amount is input to the input port from the air flow meter 19 provided in the intake passage 3, and the throttle valve 16 is opened from the throttle opening sensor 20 provided in the throttle valve 16. A detection signal related to the degree is input. A detection signal related to the temperature T of the exhaust purification device 30 is input from the temperature detection sensor 21 provided in the exhaust purification device 30, and a detection signal related to the oxygen concentration of exhaust gas is input from the oxygen concentration sensor 29 provided in the exhaust passage 26. The Further, the diesel engine 1 is provided with an engine rotation speed sensor 23 that detects a rotation speed of a crankshaft (not shown) and an accelerator sensor 24 that detects an operation amount of an accelerator pedal (not shown). A detection signal related to the rotational speed NE is input from the engine rotational speed sensor 23 to the input port, and the accelerator sensor 24 requests a load on the diesel engine 1 based on the accelerator operation amount (for example, an accelerator operation for the maximum value of the accelerator operation amount). A detection signal relating to the ratio of the current value of the quantity) is input. The diesel engine 1 includes a vehicle speed sensor that detects the vehicle speed of a vehicle on which the diesel engine 1 is mounted, in addition to these various sensors.

  The electronic control unit 25 grasps the operating state of the diesel engine 1 based on detection signals from various sensors. The electronic control unit 25 stores data for grasping various operation states of the diesel engine 1 in the storage unit, and compares the input various detection signals with the data to determine the operation state of the diesel engine 1. To grasp. For example, when there is no required load on the diesel engine 1 based on the accelerator operation amount and the rotational speed NE is higher than the fuel cut rotational speed NE1 included in the data, the electronic control unit 25 operates at a high speed. Understand that the vehicle is in a decelerating operation from a high load range.

  The fuel injection valves 4a to 4d, the additive injection valve 5, the supply pump 10, the EGR valve 15, the actuator 17 for driving the throttle valve 16, and the like are electrically connected to the output port of the electronic control unit 25, respectively. ing. The electronic control unit 25 grasps the operation state of the diesel engine 1 based on the detection signals input from the various sensors, and outputs a command signal corresponding to the grasped operation state to each of the above parts via the output port. Thus, the electronic control unit 25 performs various controls such as fuel injection control, additive injection control, and EGR control.

  As the fuel injection control, the electronic control unit 25 calculates the fuel injection time and the fuel injection timing to be injected from the fuel injection valves 4a to 4d based on the accelerator operation amount, the rotational speed NE, etc. 4a to 4d are driven to inject fuel into the corresponding cylinders # 1 to # 4.

  Further, the electronic control unit 25 executes a fuel cut that temporarily stops fuel injection from the fuel injection valves 4a to 4d as fuel injection control. This fuel cut is executed according to various operating states of the diesel engine 1, and an example thereof is a deceleration fuel cut. In this deceleration fuel cut, the execution condition (deceleration fuel cut condition) is that the operation state of the diesel engine 1 is a decelerating operation state from the high rotation high load region in order to reduce unnecessary fuel injection and improve fuel efficiency. is there. The electronic control unit 25 executes the deceleration fuel cut when the deceleration fuel cut condition is satisfied. Further, the electronic control unit 25 restarts the operation of the accelerator pedal from the deceleration operation state, or the rotation speed NE is lower than the fuel cut rotation speed NE1, that is, the operation state of the diesel engine 1 is the deceleration operation. The deceleration fuel cut is stopped on condition that the state is switched to a different operation state.

  The electronic control unit 25 executes the additive injection control for reducing NOx stored in the NOx storage reduction catalyst 31 and oxidizing and removing PM trapped in the filter 32. The additive injection control is executed by injecting unburned fuel from the additive injection valve 5 and supplying the unburned fuel to the exhaust purification device 30 together with exhaust gas.

  The electronic control unit 25 executes EGR control for adjusting the amount of exhaust gas introduced into the intake system, that is, the EGR amount. In this EGR control, the opening / closing control of the EGR valve 15 and the opening / closing control of the throttle valve 16 are executed based on the intake air amount detected by the air flow meter 19, the oxygen concentration detected by the oxygen concentration sensor 29, the fuel injection amount, and the like. The Specifically, first, the air-fuel ratio of the air-fuel mixture burned in the cylinder of the diesel engine 1 is calculated based on the oxygen concentration, fuel injection amount, etc. of the exhaust, and based on the air-fuel ratio, intake air amount, and oxygen concentration. The current EGR rate Er (ratio between the EGR amount and the intake air amount) is calculated. Next, the electronic control unit 25 calculates a target EGR rate Et that is a control target value of the EGR rate Er using an EGR map in which the EGR amount is associated with the fuel injection amount and the rotational speed NE. Then, the electronic control unit 25 calculates a target EGR opening and a target throttle valve opening that are control target values of the EGR valve 15 and the throttle valve 16 so that the current EGR rate Er becomes the target EGR rate Et, The EGR valve 15 and the throttle valve 16 are controlled to be opened and closed based on the target EGR opening and the target throttle valve opening.

  The electronic control unit 25 performs PM removal processing to remove PM accumulated on the upstream end surface 31a of the NOx storage reduction catalyst 31 as EGR control. The electronic control unit 25 stores a rotation speed threshold, which is a condition for executing the PM removal process, as the PM removal rotation speed NE2. The PM removal rotational speed NE2 is higher than the fuel cut rotational speed NE1 that is the lower limit value of the rotational speed in the deceleration fuel cut condition (NE1 <NE2). When the rotational speed NE is higher than the PM removal rotational speed NE2 and the deceleration fuel cut condition is satisfied, the electronic control unit 25 opens the throttle valve 16 and fully closes the EGR valve 15. To do. As a result, a large amount of intake air corresponding to the PM removal rotational speed NE2 is vigorously blown to the end face 31a of the NOx storage reduction catalyst 31 without being recirculated. As a result, the PM accumulated on the end surface 31a of the NOx storage reduction catalyst 31 is removed with the flow of the exhaust gas and blown off to the downstream filter 32. The electronic control unit 25 opens and closes the throttle valve 16 and the EGR valve 15 so that the EGR rate Er becomes the target EGR rate Et based on the EGR control on condition that the execution condition of the PM removal process is not satisfied. Control.

  When the PM removal process is executed, the NOx occlusion reduction catalyst 31 is cooled by a large amount of exhaust gas flowing into the exhaust emission control device 30 because there is no heat release due to combustion with the execution of the fuel cut. For this reason, if the above-described PM removal process is performed excessively, there is a concern that the catalytic performance may be reduced due to a temperature drop of the NOx storage reduction catalyst 31 disposed in the exhaust purification device 30. Therefore, the electronic control unit 25 stores, as the PM removal temperature Ts, the lower limit temperature T of the exhaust purification device 30 at which the catalytic performance of the NOx storage reduction catalyst 31 is sufficiently secured, and the temperature T is changed to PM in the PM removal process. When the temperature is lower than the removal temperature Ts, the PM removal process is terminated and the opening / closing control based on the EGR control is executed. That is, in the PM removal process, the rotational speed NE is lower than the PM removal rotational speed NE2, the fuel cut condition is not satisfied, and the temperature T of the NOx storage reduction catalyst 31 is lower than the PM removal temperature Ts. Each is set as an end condition, and the process ends when one of the end conditions is satisfied.

Hereinafter, the control routine of the PM removal process will be described with reference to FIG. FIG. 2 is a flowchart for explaining a control routine of the PM removal process. The control routine is repeatedly executed by the electronic control device 25 from the start of the diesel engine 1. That is, the electronic control unit 25 executes fuel injection based on the fuel injection control and opening / closing control of the EGR valve 15 and the throttle valve 16 based on the EGR control as a preceding stage for executing the control routine.

  When executing the control routine of the PM removal process, first, the electronic control unit 25 grasps the operating state of the diesel engine 1 based on detection signals from various sensors, and the rotational speed NE of the diesel engine 1 is determined as the PM removal rotational speed. It is determined whether it is larger than NE2. If the rotational speed NE is greater than the PM removal rotational speed NE2 (step S11: YES), the electronic control unit 25 determines whether or not a deceleration fuel cut condition is established based on the operating state, and the deceleration fuel cut condition. Is established (step S12: YES), the EGR valve 15 is fully closed and the throttle valve 16 is fully opened (step S13).

  Thus, a large amount of exhaust gas corresponding to the PM removal rotational speed NE2 is vigorously blown to the end surface 31a of the NOx storage reduction catalyst 31 without being recirculated, and the PM accumulated on the end surface 31a of the NOx storage reduction catalyst 31 is increased. It is removed according to the flow of this exhaust. And since the said control is performed in the state in which there is no request | requirement load to the diesel engine 1, when performing this PM removal process, a fall of operativity is not caused with respect to the increase in a request | requirement load.

  The electronic control unit 25 ends this routine when the rotational speed NE is lower than the PM removal rotational speed NE2 (step S11: NO) or when the deceleration fuel cut condition is not satisfied (step S12: NO). To do.

  When the electronic control unit 25 executes the PM removal process, the electronic control unit 25 determines whether or not the above-described PM removal process end condition is satisfied based on detection signals from various sensors, and the PM removal process end condition is satisfied. If not (step S14: NO), the fully closed state of the EGR valve 15 and the fully opened state of the throttle valve 16 are maintained until the PM removal processing termination condition is satisfied. On the other hand, when the PM removal process termination condition is satisfied (step S14: YES), the electronic control unit 25 controls the opening and closing of the EGR valve 15 and the throttle valve 16 based on the EGR control, and the additive injection valve 5 To supply exhaust gas containing unburned fuel components to the exhaust gas purification device 30. Then, the NOx occluded by the NOx occlusion reduction catalyst 31 is reduced and exhausted, and the PM collected by the filter 32 is oxidized and removed using the oxidation heat of the unburned fuel component. At this time, since PM accumulated on the end face 31a is removed by the PM removal process, recovery of the purification ability of the exhaust purification apparatus can be more effectively performed.

As described above, according to the above embodiment, the following effects can be obtained.
(1) When executing the deceleration fuel cut from the state where the rotational speed NE is higher than the PM removal rotational speed NE2, the EGR valve 15 is fully closed and the throttle valve 16 is fully opened. As a result, since a large amount of intake air corresponding to the PM removal rotational speed NE2 is sucked into the combustion chamber while exhaust gas recirculation is stopped, exhaust can be blown vigorously onto the end surface 31a of the NOx storage reduction catalyst 31. The PM deposited on the end face 31a can be removed by blowing away. In addition, while the deceleration fuel cut is being performed, there is no accelerator operation by the driver and there is no required load on the diesel engine 1, so that it is possible to reliably avoid a decrease in the drivability of the diesel engine 1. In addition, since it is not necessary to provide a new mechanism for removing PM accumulated on the end surface 31a of the NOx storage reduction catalyst 31, this can be realized while avoiding cost increase.

  (2) Since the PM removal rotational speed NE2 is higher than the fuel cut rotational speed NE1, the PM removal process is executed at a higher speed even in the deceleration operation state. As a result, the PM removal process is executed when the exhaust gas flow rate is high even in the deceleration operation state, and therefore PM accumulated on the end face 31a can be efficiently removed.

(3) When the temperature T of the exhaust purification device 30 is lower than the PM removal temperature Ts, the PM removal process is terminated. Therefore, excessive cooling of the exhaust purification device 30 accompanying the exhaust blowing, that is, a reduction in purification capability, is performed. Can be prevented.

  (4) In order to supply exhaust gas containing unburned fuel components to the exhaust gas purification device 30 immediately after the PM removal process is completed, recovery of the purification capability in the exhaust gas purification device 30 with no or much PM accumulation And the recovery of the purification ability can be carried out more effectively.

In addition, you may change the said embodiment as follows.
In the above embodiment, the additive for removing PM by oxidation is embodied in the unburned fuel from the additive injection valve 5. In addition, when the additive is the fuel of the diesel engine 1, the additive injection valve 5 is omitted, and the post-injection by the fuel injection valves 4a to 4d is performed again at a timing delayed from the execution timing of the main injection. By performing (fuel injection), the PM collected by the filter 32 may be removed by oxidation. Further, the fuel supply by the additive injection valve 5 and the fuel supply by the post injection may be used in combination.

  In the above embodiment, the additive from the additive injection valve 5 serving as the addition control means is the fuel of the diesel engine 1, but the additive is not limited to this, and an additive that enables recovery of the purification action of the exhaust purification device (for example, Any material may be used as long as it is urea.

  In the above embodiment, the additive injection control is executed immediately after the PM removal process. However, the present invention is not limited to this. For example, when oxidizing and removing PM, the additive injection control may be executed periodically every predetermined time, for example. Good.

  In the above embodiment, when the temperature T of the exhaust purification device 30 becomes lower than the PM removal temperature Ts, the PM removal process is terminated. In addition to this, in removing PM, regardless of the temperature T of the exhaust purification device 30, the PM removal amount is estimated and the PM removal processing is executed when the accumulation amount exceeds a predetermined threshold value. Good.

  -The PM removal process in the above embodiment was performed during execution of the deceleration fuel cut. The present invention is not limited to this, and in order to execute the PM removal process, it is sufficient that the rotational speed NE is equal to or higher than the PM removal rotational speed NE2 and the fuel cut condition is satisfied. This fuel cut is, for example, an over-rotation fuel cut that is executed when the rotational speed NE exceeds a predetermined rotational speed for a predetermined time, or a fastest fuel cut that is executed when the vehicle exceeds a predetermined maximum speed. May be.

  In the above embodiment, one NOx storage reduction catalyst 31 is disposed upstream of the filter 32. However, the present invention is not limited to this, and various catalysts such as an oxidation catalyst and a three-way catalyst are appropriately disposed upstream of the filter 32. The structure which provides one or more may be sufficient, and the structure which provides various catalysts downstream of a filter may be sufficient.

  -Although the diesel engine 1 of the said embodiment was an in-line 4 cylinder diesel engine, this invention is applicable similarly to the diesel engine provided with the number of cylinders and cylinder arrangement | sequences.

  The turbocharger 11 that supercharges the intake air in the intake passage 3 using exhaust is provided in the diesel engine 1 of the above embodiment. Not limited to this, the turbocharger 11 may be omitted in executing the PM removal processing.

In the above embodiment, the exhaust system is embodied by the exhaust passage 26 and the exhaust manifold 8, but the exhaust system may be configured by only the exhaust passage 26.
In the above embodiment, the fuel cut unit, the temperature detection unit, the additive control unit, and the EGR control unit are embodied by one electronic control unit 25, but these units may be embodied by a plurality of electronic control units. .

  In the PM removal process of the above embodiment, the throttle valve 16 is fully opened and the EGR valve 15 is fully closed. However, the opening of the throttle valve 16 is limited to the fully open state as long as the amount of EGR gas is reduced and a large amount of exhaust gas can be blown to the end face 31a of the NOx storage reduction catalyst 31 at the time of high engine rotation. The opening degree of the EGR valve 15 may be changed as appropriate without being limited to the fully closed state.

Schematic which shows the internal combustion engine and its periphery structure in this embodiment. The flowchart explaining the control routine of PM removal processing in this embodiment.

Explanation of symbols

  Er ... EGR rate, Et ... target EGR rate, NE ... rotational speed, NE1 ... fuel cut rotational speed, NE2 ... PM removal rotational speed, T ... temperature, Ts ... PM removal temperature as a threshold, 1 ... diesel engine, 2 ... Cylinder head, 3 ... Intake passage, 4a-4d ... Fuel injection valve, 5 ... Additive injection valve, 6a-6d ... Exhaust port, 7 ... Intake manifold, 8 ... Exhaust manifold, 9 ... Common rail, 10 ... Supply pump, DESCRIPTION OF SYMBOLS 11 ... Turbocharger, 13 ... EGR passage, 14 ... EGR cooler, 15 ... EGR valve, 16 ... Throttle valve, 17 ... Actuator, 18 ... Intercooler, 19 ... Air flow meter, 20 ... Throttle valve opening sensor, 21 ... Temperature Detection sensor, 23 ... rotational speed sensor, 24 ... accelerator sensor, 25 ... electronic control unit, 26 ... exhaust passage, 2 ... fuel supply pipe, 29 ... oxygen sensor, 30 ... exhaust gas purifying apparatus, 31 ... NOx storage reduction catalyst, 31a ... end surface, 32 ... filter.

Claims (6)

EGR part of the exhaust gas from the upstream of the exhaust gas purification device provided in the exhaust system of the internal combustion engine to the intake system of the internal combustion engine in an aspect having an exhaust gas purification catalyst and a collector for purifying exhaust gas from the internal combustion engine EGR control means for controlling opening and closing of an EGR valve that allows recirculation as gas and a throttle valve provided in the intake system so that an EGR rate becomes a target value corresponding to an operating state of the internal combustion engine, and the internal combustion engine A control device for an internal combustion engine, comprising: fuel cut means for judging whether or not a fuel cut condition is established based on an operating state of the engine and controlling fuel cut based on the judgment result;
When the rotational speed of the internal combustion engine is equal to or higher than a threshold value and the fuel cut condition is satisfied, the throttle valve is opened to a predetermined position by the EGR control means while performing the fuel cut by the fuel cut means, and A control device for an internal combustion engine, wherein the EGR valve is closed to a predetermined position.   When the rotational speed of the internal combustion engine is equal to or higher than a threshold value and the fuel cut condition is satisfied, the throttle valve is fully opened by the EGR control means while the fuel cut is being executed by the fuel cut means, and 2. The control device for an internal combustion engine according to claim 1, wherein the EGR valve is fully closed.   The control device for an internal combustion engine according to claim 1, wherein the fuel cut condition is a deceleration fuel cut condition.   The control device for an internal combustion engine according to claim 3, wherein a threshold value of the rotational speed is higher than a lower limit value of the rotational speed in the deceleration fuel cut condition. The control device for an internal combustion engine according to any one of claims 1 to 4,
Temperature detecting means for detecting the temperature of the exhaust purification catalyst,
When the rotational speed of the internal combustion engine is equal to or higher than a threshold value and the temperature of the exhaust purification catalyst is equal to or lower than the threshold value from a state where the fuel cut condition is satisfied, the throttle valve is controlled so that the EGR rate becomes a target value. A control device for an internal combustion engine, characterized in that the opening and the opening of the EGR valve are changed. The control apparatus for an internal combustion engine according to any one of claims 1 to 5,
An addition control means for adding an additive for recovering the purification ability of the exhaust purification device to the exhaust purification device;
An internal combustion engine control device, wherein the additive is added to the exhaust purification device by the addition control means after the throttle valve is opened to a predetermined position and the EGR valve is closed to a predetermined position.

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