JP2019035336A - Control device for internal combustion engine and vehicle - Google Patents

Abstract

To provide a control device for an internal combustion engine having a storage type NOx catalyst which can increase a frequency of execution of rich spike without deteriorating a driving feeling.SOLUTION: A control device 60 for an internal combustion engine 10 having a storage type NOx catalyst 41 in an exhaust passage 30 includes a fuel supply control section 61 for controlling execution and a stop of fuel supply to a combustion chamber of the internal combustion engine 10 so as to be interlocked with on/off of driver's accelerator operation, and a rich spike execution control section 62 for instructing execution of rich spike with respect to the fuel supply control section 61. The rich spike execution control section 62 causes the fuel supply control section 61 to start execution of the rich spike in accordance with timing when the accelerator operation is switched to an on state from an off state.SELECTED DRAWING: Figure 3

Description

  The present disclosure relates to an internal combustion engine control device and a vehicle.

  As an exhaust purification device disposed in an exhaust passage of an internal combustion engine (hereinafter referred to as “engine”) mounted on a vehicle, an occlusion-type NOx catalyst that purifies NOx in exhaust gas is known.

  Such an occlusion-type NOx catalyst occludes the NOx in the exhaust gas by adhering it as nitrate when the oxygen in the exhaust gas is excessive. The occlusion-type NOx catalyst reacts with the occluded NOx with carbon monoxide or the like in the exhaust gas in a reducing atmosphere, and reduces and releases it into a harmless gas such as nitrogen.

  The NOx storage catalyst cannot store NOx when NOx storage progresses and the NOx saturation state is reached. Therefore, when the NOx of the storage-type NOx catalyst is saturated, the engine is operated at a rich air-fuel ratio (hereinafter referred to as “rich spike”), thereby forcibly generating a reducing atmosphere of exhaust gas. Control for purging NOx of the NOx catalyst is performed (see, for example, Patent Document 1).

  However, since the NOx purge of the storage-type NOx catalyst cannot be effectively performed depending on the operating state of the engine, the ECU (Electronic Control Unit) or the like normally determines the timing for performing the rich spike.

JP 2007-270646 A

  By the way, in recent vehicles, the engine tends to be operated at a lean air-fuel ratio in order to improve fuel consumption, and NOx is easily stored in the storage-type NOx catalyst. Further, the NOx storage efficiency of the storage-type NOx catalyst decreases as NOx approaches a saturated state. From this point of view, there is a request to increase the execution frequency of rich spikes.

  On the other hand, since the rich spike is accompanied by fluctuations in engine output, it may cause a torque shock and lead to deterioration in driving feeling.

  The present disclosure has been made in view of the above-described problems, and in an internal combustion engine having an occlusion-type NOx catalyst in an exhaust passage, it is possible to increase the frequency of execution of rich spikes without causing deterioration in operation feeling. It is an object of the present invention to provide a control device for an internal combustion engine and a vehicle.

The main present disclosure for solving the above-described problems is as follows.
A control device for an internal combustion engine having a storage-type NOx catalyst in an exhaust passage,
A fuel supply control unit that controls execution and stop of fuel supply to the combustion chamber of the internal combustion engine so as to be linked with on / off of the accelerator operation of the driver;
A rich spike execution control unit that instructs the fuel supply control unit to execute a rich spike;
With
The rich spike execution control unit causes the fuel supply control unit to start execution of the rich spike in accordance with a timing at which the accelerator operation is switched from an off state to an on state.
A control device for an internal combustion engine.

In other aspects,
The vehicle includes a control device for the internal combustion engine.

  According to the control device for an internal combustion engine according to the present disclosure, it is possible to increase the execution frequency of the rich spike without deteriorating the driving feeling.

The figure which shows an example of a structure of the vehicle which concerns on one Embodiment. The figure which shows an example of the control map which controls the fuel-injection apparatus which concerns on one Embodiment. The flowchart which shows an example of operation | movement of the rich spike execution control part which concerns on one Embodiment. Timing chart showing the state of each part of the vehicle when executing a rich spike according to an embodiment

[Vehicle configuration]
Hereinafter, the configuration of the vehicle A according to the embodiment will be described with reference to FIG.

  The vehicle A according to this embodiment is typically a diesel engine vehicle. The vehicle A according to the present embodiment is a manual transmission type vehicle (hereinafter, also referred to as “MT vehicle”) that allows the driver to manually switch the gear position of the transmission 11.

  FIG. 1 is a diagram illustrating an example of a configuration of a vehicle A according to the present embodiment.

  The vehicle A according to this embodiment includes an engine main body 10, a transmission 11, an intake passage 20, an exhaust passage 30, an air cleaner 21, a turbocharger 22, an EGR device 31, an exhaust purification device 40, various sensors 51 to 53, and an engine ECU 60. Etc.

  The engine body 10 includes a combustion chamber and a fuel injection device (not shown) that supplies fuel to the combustion chamber. The engine body 10 generates power for the vehicle A by repeatedly performing an air intake stroke, an air compression stroke, a combustion gas expansion stroke, and a combustion gas exhaust stroke in the combustion chamber.

  The fuel injection device of the engine body 10 operates in accordance with a control signal from an engine ECU 60 (hereinafter abbreviated as “ECU 60”).

  The engine body 10 according to the present embodiment is a four-cylinder engine, and branches from the intake passage 20 into four combustion chambers via intake manifolds, and the exhaust passage 30 passes from the four combustion chambers through exhaust manifolds. It becomes the composition which joins.

  The transmission 11 is connected to the engine main body 10 via a clutch, converts the rotational speed and torque of the rotational power generated by the engine main body 10, and transmits them to the drive wheel side (not shown). The transmission 11 according to the present embodiment is, for example, a manual transmission, and according to a shift speed switching operation (hereinafter, abbreviated as “shift speed switching operation”) performed by a driver on a shift lever, The speed change mechanism is operated to change the gear position.

  The intake passage 20 is a flow path that sucks fresh air (air) from the intake port 20 a and supplies the fresh air to the engine body 10. In the intake passage 20, an air cleaner 21, a compressor of a turbocharger 22, and an intake throttle valve 23 are provided in order from the upstream intake port 20 a to the combustion chamber.

  The air cleaner 21 is supplied with air sucked from the air inlet 20a, removes impurities from the air, and sends the air to the turbocharger 22 side.

  The turbocharger 22 rotates the turbine using the pressure of the exhaust gas in the exhaust passage 30, operates the coaxial compressor by the rotational motion of the turbine, compresses the air flowing through the intake passage 20, It sends out to the engine body 10 side.

  The intake throttle valve 23 adjusts the amount of air flowing through the intake passage 20.

  The exhaust passage 30 is a flow path for discharging the exhaust gas after combustion discharged from the engine body 10 to the outside of the vehicle A. The exhaust passage 30 is provided with an EGR device 31, a turbine of the turbocharger 22, and an exhaust purification device 40 in order from the engine body 10 toward the downstream side.

  The EGR device 31 circulates a part of the exhaust gas flowing through the exhaust passage 30 to the intake passage 20. The EGR device 31 communicates the exhaust passage 30 and the intake passage 20, and allows EGR passage 31 a and EGR passage to pass a part of the exhaust gas exhausted from the combustion chamber 11 to the exhaust passage 30 toward the intake passage 20. It includes an EGR cooler 31b that cools the exhaust gas flowing through 31a, an EGR valve 31c that adjusts the amount of exhaust gas flowing through the EGR passage 31a, and the like.

  The exhaust purification device 40 includes an occlusion-type NOx catalyst 41 and a PM filter 42.

  The storage-type NOx catalyst 41 stores NOx in the exhaust gas when oxygen in the exhaust gas is excessive, and reacts the stored NOx with carbon monoxide or the like in the exhaust gas in a reducing atmosphere. Reduce to a harmless gas such as nitrogen and release. As the occlusion type NOx catalyst 41, a known occlusion type NOx catalyst can be used. For example, platinum or rhodium can be used as the catalyst, and barium or the like can be used as the occlusion material.

  The storage state of NOx in the storage-type NOx catalyst 41 is monitored by the ECU 60, and NOx purge (rich spike) is periodically executed (details will be described later).

  The PM filter 42 captures PM (Particulate Matter) contained in the exhaust gas.

  Various sensors 51 to 53 are provided for detecting the state of each part of the vehicle A and the like. Specifically, each part of the vehicle A detects a shift position sensor 51 that detects a gear change operation performed by the driver, an accelerator opening sensor 52 that detects an accelerator operation performed by the driver, and an engine speed. A crank angle sensor 53 and the like are provided. And these various sensors 51-53 sequentially transmit to ECU60 as the detection signal the information obtained by detection (dotted line in FIG. 1).

  The ECU 60 (corresponding to the “control device” of the present invention) is an electronic control unit that controls the fuel injection device of the engine body 10, and includes, for example, a CPU (Central Processing Unit), ROM (Read Only Memory), RAM ( Random Access Memory), an input port, an output port, and the like. The ECU 60 communicates with each part of the vehicle A to control them and receive data from them.

  The ECU 60 includes a fuel supply control unit 61 and a rich spike execution control unit 62.

  The fuel supply control unit 61 controls execution and stop of fuel supply to the combustion chamber of the engine body 10 so as to be interlocked with the on / off of the accelerator operation by the driver. The fuel supply control unit 61 uses, for example, a control map to determine the operating state of the fuel injection device and to control the opening and closing of the solenoid valve of the fuel injection device, thereby controlling the fuel supplied from the fuel injection device to the combustion chamber. The injection timing and the injection amount are controlled.

FIG. 2 is a diagram illustrating an example of a control map for controlling the fuel injection device. The horizontal axis in FIG. 2 is the engine speed [rpm], the vertical axis is the fuel injection amount [m ³ / s], and FIG. 2 shows a control map when the accelerator opening is 100%, the accelerator opening. A control map when A is 50% and a control map when the accelerator opening is 0% are shown.

  Further, when the rich spike execution control unit 62 generates a rich spike start command, the fuel supply control unit 61 starts execution of the rich spike (hereinafter also referred to as “rich spike mode”). For example, when the rich spike is executed, the fuel supply control unit 61 controls the fuel injection device using a control map for executing the rich spike. The rich spike execution control map includes, for example, an operation in which the air-fuel ratio is richer than in normal operation (hereinafter also referred to as “normal mode”) (for example, the fuel supply amount is increased by 1.5 times). ) Is set as follows.

  The rich spike execution control unit 62 controls the start and end of the rich spike in the fuel supply control unit 61. The rich spike execution control unit 62 generates a rich spike mode start command when the storage amount of the NOx storage 41 increases, and causes the fuel supply control unit 61 to start a rich spike. The rich spike execution control unit 62 causes the fuel supply control unit to end the rich spike mode at a predetermined end timing after the fuel supply control unit starts operating in the rich spike mode.

  However, the rich spike execution control unit 62 controls the start timing of the rich spike so as to be linked to the accelerator operation in order to alleviate the uncomfortable feeling felt by the driver due to the torque shock generated when the rich spike is started (details). Will be described later).

  The rich spike execution control unit 62 determines that the NOx occlusion amount of the occlusion-type NOx catalyst 41 has increased based on, for example, the cumulative value of the driving mileage, the cumulative value of the fuel injection amount, or the detection signal of the NOx sensor. Detect. When the initial state of the NOx storage amount of the storage-type NOx catalyst 41 is 0% and the saturation state is 100%, the rich spike execution control unit 62, for example, increases the NOx storage amount to about 60%. Start running.

  The fuel supply control unit 61 and the rich spike execution control unit 62 described above are realized, for example, when the CPU refers to control programs and various data stored in a ROM, a RAM, and the like. However, the function is not limited to processing by software, and can of course be realized by a dedicated hardware circuit.

[ECU operation flow]
Next, the operation when the rich spike execution control unit 62 controls the start timing of the rich spike will be described with reference to FIGS.

  FIG. 3 is a flowchart showing an example of the operation of the rich spike execution control unit 62.

  The flowchart shown in FIG. 3 is executed, for example, by the rich spike execution control unit 62 at a predetermined interval (for example, every second) according to the computer program. Here, it is assumed that the rich spike execution control unit 62 operates in parallel with the fuel supply control unit 61.

FIG. 4 is a timing chart showing the state of each part of the vehicle A when executing the rich spike. In FIG. 4, the output torque [N · m], the operation mode (normal mode or rich spike mode), the fuel supply amount [m ³ / s] of the fuel injection device, and the accelerator opening state along the time axis Is shown. Note that T1 in FIG. 4 indicates the timing at which the driver has performed the gear shift operation, and T2 indicates the timing at which the driver has performed the accelerator operation.

  In step S1, the rich spike execution control unit 62 determines whether or not rich spike execution is necessary. The rich spike execution control unit 62 estimates the NOx occlusion amount of the storage NOx catalyst 41 from the accumulated value of the driving travel distance from the previous rich spike time, for example, and whether or not it is necessary to execute the rich spike. Determine. When the rich spike execution control unit 62 determines that it is necessary to execute the rich spike (step S1: YES), the rich spike execution control unit 62 executes the subsequent processing of step S2. On the other hand, when the rich spike execution control unit 62 determines that the execution of the rich spike is unnecessary (step S1: NO), the series of flow ends.

  In step S2, the rich spike execution control unit 62 waits for a gear change operation to be performed based on the detection signal acquired from the shift position sensor 51 (step S2: NO). Then, when the driver detects the execution of the gear position switching operation (step S2: YES), the rich spike execution control unit 62 executes the subsequent process of step S3.

  In step S2, the rich spike execution control unit 62 detects the timing at which the driver turns off the accelerator operation for a predetermined time based on the timing of the gear position switching operation (timing T1 in FIG. 4).

  Step S2 is a determination flow that is set based on the general driving characteristics of the driver that the accelerator operation is turned off for a certain period of time when the gear position switching operation is performed. More specifically, the driver generally turns off the accelerator operation once when the gear shift operation is performed, and after the gear shift is completed, to return the speed of the vehicle A It has a driving characteristic that the accelerator operation is kept on for a certain period of time. In the present embodiment, such driving characteristics are used.

  In step S2, the rich spike execution control unit 62 may detect the timing at which the accelerator operation is turned off instead of the shift speed switching operation.

  In step S3, the rich spike execution control unit 62 waits for the timing at which the accelerator operation is turned on by the detection signal acquired from the accelerator opening sensor 52 (step S3: NO). And rich spike execution control part 62 performs processing of following Step S4, when a driver's accelerator operation is detected (Step S3: YES).

  In step S4, the rich spike execution control unit 62 sets the operation mode of the fuel supply control unit 61 to the rich spike mode. Accordingly, the fuel supply control unit 61 starts control of the fuel injection device of the engine body 10 in the rich spike mode.

  The timing for starting the rich spike in step S4 corresponds to the timing T2 in FIG. At this time, in the vehicle A, the output torque and the acceleration temporarily increase because the fuel injection of the fuel injection device is resumed from the stopped state in conjunction with the accelerator operation. As a result, a certain level of torque shock is also given to the driver. However, in the vehicle A according to the present embodiment, the torque fluctuation occurs almost simultaneously with the timing of the accelerator operation, so that the torque shock is less uncomfortable for the driver.

  In step S5, the rich spike execution control unit 62 waits for a timing at which a rich spike end condition (for example, rich spike execution time) is satisfied (step S5: NO). When the rich spike execution control unit 62 satisfies the rich spike end condition (step S5: YES), the rich spike execution control unit 62 executes the subsequent process of step S6.

  In step S <b> 6, the rich spike execution control unit 62 ends the rich spike mode in the fuel supply control unit 61. As a result, the fuel supply control unit 61 starts control of the fuel injection device of the engine body 10 in the normal mode.

  As described above, according to the ECU 60 according to the present embodiment, the start timing of the rich spike can be matched with the timing when the driver turns on from the state where the accelerator operation is temporarily turned off. Therefore, the driver's uncomfortable feeling due to torque fluctuation when starting the rich spike can be alleviated.

  In particular, the ECU 60 according to the present embodiment can start a rich spike at the timing when the accelerator operation is turned on immediately after the gear change operation of the transmission 11 is performed. Therefore, by utilizing the driving characteristics of the driver at the time of the gear shift operation, it is possible to secure the time for continuously executing the rich spike and to reliably execute the NOx purge of the storage type NOx catalyst 41.

(Other embodiments)
The present invention is not limited to the above embodiment, and various modifications can be considered.

  In the above embodiment, a manual transmission is shown as an example of the transmission 11, but an automatic transmission may be applied.

  In the above embodiment, as an example of the configuration of the ECU 60, the functions of the fuel supply control unit 61 and the rich spike execution control unit 62 are described as being realized by a single computer, but may be realized by a plurality of computers. Of course it is good. For example, the function of the fuel supply control unit 61 and the function of the rich spike execution control unit 62 may be mounted on separate ECUs.

  Moreover, in the said embodiment, although the aspect which performs the process of the fuel supply control part 61 and the rich spike execution control part 62 in parallel was shown as an example of a structure of ECU60, as an aspect performed in a series of flows Also good.

  In the above-described embodiment, a mode applied to a diesel engine vehicle will be described as an example of the vehicle A to which the ECU 60 is applied. However, the ECU 60 according to the present invention can also be applied to a gasoline engine vehicle.

  As mentioned above, although the specific example of this invention was demonstrated in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

  According to the control device for an internal combustion engine according to the present disclosure, it is possible to increase the execution frequency of the rich spike without deteriorating the driving feeling.

DESCRIPTION OF SYMBOLS 10 Engine main body 20 Intake passage 21 Air cleaner 22 Turbocharger 23 Intake throttle valve 30 Exhaust passage 31 EGR device 40 Exhaust purification device 41 Occlusion type NOx catalyst 42 PM filter 51 Shift position sensor 52 Accelerator opening sensor 53 Crank angle sensor 60 Engine ECU

Claims (4)

A control device for an internal combustion engine having a storage-type NOx catalyst in an exhaust passage,
A fuel supply control unit that controls execution and stop of fuel supply to the combustion chamber of the internal combustion engine so as to be linked with on / off of the accelerator operation of the driver;
A rich spike execution control unit that instructs the fuel supply control unit to execute a rich spike;
With
The rich spike execution control unit causes the fuel supply control unit to start execution of the rich spike in accordance with a timing at which the accelerator operation is switched from an off state to an on state.
Control device for internal combustion engine. Applies to vehicles where the driver can manually change the gear position of the transmission,
The rich spike execution control unit
On the condition that the transmission stage switching operation of the transmission has been performed, the fuel supply control unit is synchronized with the timing at which the accelerator operation is switched from the off state to the on state following the transmission stage switching operation. Starting execution of the rich spike,
The control apparatus for an internal combustion engine according to claim 1. Applied to diesel engine vehicles,
The control apparatus for an internal combustion engine according to claim 1 or 2. A vehicle comprising the control device for an internal combustion engine according to any one of claims 1 to 3.

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