JP2022018822A - Control device of internal combustion engine - Google Patents

Abstract

To suppress occurrence of problems due to opening/closing of a valve in a temperature raising control mode.SOLUTION: A control device 100 includes: a valve control portion 125 for controlling a degree of opening of an intake throttle valve 28 provided in an intake passage in an openable/closable manner in order to control a supercharging pressure; a timing specification portion 122 for specifying a start timing or a stop timing of feedback control of the supercharging pressure by the intake throttle valve 28 during execution of a temperature raising control mode for raising a temperature of an after-treatment device to purify an exhaust gas; an operating direction determination portion 123 for determining whether the intake throttle valve 28 is operated to be opened in an opening direction, or operated to be closed in a closing direction in the start timing or the stop timing specified by the timing specification portion 122; and a transition time setting portion 124 for setting a transition time to a target degree of opening in an operating direction of the intake throttle valve 28 according the an operating direction of the intake throttle valve 28 determined by the operating direction determination portion 123.SELECTED DRAWING: Figure 3

Description

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

In the internal combustion engine, the boost pressure of the intake air flowing through the main body of the internal combustion engine is adjusted by controlling the opening degree of the valve provided in the intake passage.
Further, the internal combustion engine is provided with an aftertreatment device (for example, a catalyst) for purifying the exhaust gas, and in order to activate the catalyst, a temperature rise control mode for raising the temperature of the catalyst is executed.

Japanese Unexamined Patent Publication No. 2009-79557

By the way, normally, the transition time at which the valve closes and the transition time at which the valve opens are set to the same time in advance. Therefore, if the valve closing time is short at the start of the feedback control during the temperature rise control mode, the intake air amount may be insufficient and the internal combustion engine main body may misfire. On the other hand, if the valve opens for a short time when the feedback control is stopped, acceleration may be poor.

Therefore, the present invention has been made in view of these points, and an object thereof is to suppress the occurrence of a defect due to opening and closing of a valve in the temperature rise control mode.

In one aspect of the present invention, in order to control the boost pressure of the air flowing to the internal combustion engine main body, a valve control unit for controlling the opening degree of a valve provided in the intake passage so as to be openable and closable, and the internal combustion engine main body. While executing the temperature rise control mode for raising the temperature of the aftertreatment device that purifies the exhaust gas generated from the valve, the timing specifying unit for specifying the start timing or the stop timing of the feedback control of the boost pressure by the valve, and the timing. At the start timing or the stop timing specified by the specific unit, the operation direction determination unit determines whether the valve opens in the open direction or closes in the closed direction, and the operation direction determination unit determines. Provided is a control device for an internal combustion engine, comprising a transition time setting unit for setting a transition time to a target opening degree of the valve in the operating direction according to the operating direction of the valve.

The closing transition time setting unit is such that the closing transition time in which the valve closes to the target opening in the closing direction is longer than the opening transition time in which the valve opens to the target opening in the opening direction. The transition time and the open transition time may be set.

Further, the operating direction determination unit may determine the operating direction of the valve based on the difference between the opening degree of the valve before the transition and the opening degree of the valve after the transition.

Further, the operation direction determination unit determines that the valve operates in the open direction when the difference is larger than a predetermined threshold value at the stop timing, and when the difference is equal to or less than the threshold value. May determine that the valve closes in the closing direction.

Further, the operation direction determination unit determines that the valve closes in the closing direction when the difference is larger than a predetermined threshold value at the start timing, and when the difference is equal to or less than the threshold value. May determine that the valve opens in the opening direction.

According to the present invention, there is an effect that the occurrence of a defect due to the opening and closing of the valve in the temperature rise control mode can be suppressed.

It is a schematic diagram for demonstrating the structure of the internal combustion engine 1 which concerns on one Embodiment. It is a schematic diagram for demonstrating the transition time at the time of opening and closing of an intake throttle valve 28. It is a schematic diagram for demonstrating the detailed structure of a control device 100. It is a schematic diagram for demonstrating the determination of the operation direction of the intake throttle valve 28.

<Composition of internal combustion engine>
The configuration of the internal combustion engine according to the embodiment of the present invention will be described with reference to FIG.

FIG. 1 is a schematic diagram for explaining the configuration of the internal combustion engine 1 according to the embodiment. The internal combustion engine 1 is, for example, a multi-cylinder engine mounted on a vehicle such as a truck. The internal combustion engine 1 is a diesel engine, but is not limited to this, and may be, for example, a gasoline engine. As shown in FIG. 1, the internal combustion engine 1 includes an engine main body 10, a fuel injection device 15, an intake passage 20, an exhaust passage 30, a turbocharger 40, an EGR device 50, and a control device 100.

The engine body 10 has, but is not limited to, four cylinders 12 here. Movable parts such as pistons and crankshafts are provided in each cylinder 12.

The fuel injection device 15 is an injection device that injects fuel into the combustion chamber in the engine body 10. The fuel injection device 15 is a common rail type fuel injection device here, and has an injector 16 and a common rail 17. The injector 16 injects fuel into the combustion chamber in each cylinder 12. The common rail 17 stores the fuel injected from the injector 16 in a high pressure state.

The intake passage 20 is a passage through which intake air to be sucked into the engine body 10 flows. The intake passage 20 has an intake manifold 22 connected to the engine body 10 and an intake pipe 23 connected to the upstream end of the intake manifold 22. The intake manifold 22 distributes and supplies the intake air sent from the intake pipe 23 to the intake ports of each cylinder. The intake pipe 23 is provided with an air cleaner 24, an air flow meter 25, a compressor 42C of a turbocharger 40, an intercooler 27, and an intake throttle valve 28. The air flow meter 25 detects the amount of intake air per unit time of the internal combustion engine 1, that is, the intake flow rate. The opening degree of the intake throttle valve 28 can be adjusted by, for example, rotating.

The exhaust passage 30 is a passage through which the exhaust gas generated from the engine body 10 flows. The exhaust passage 30 has an exhaust manifold 32 connected to the engine body 10 and an exhaust pipe 33 connected to the downstream end of the exhaust manifold 32. The exhaust manifold 32 collects the exhaust gas sent from the exhaust port of each cylinder. The exhaust pipe 33 is provided with a turbine 42T of the turbocharger 40 and an aftertreatment device 35. The aftertreatment device 35 is a device for purifying the exhaust gas, and includes, for example, an oxidation catalyst, a DPF, an SCR, and an ammonia oxidation catalyst.

By the way, a control mode for raising the temperature of the aftertreatment device 35 (specifically, the catalyst) at an early stage from the cold start of the internal combustion engine 1 to the completion of warming up (hereinafter referred to as a temperature rise control mode). Is feasible. In the temperature rise control mode, the inhalation of fresh air is reduced, while the amount of exhaust gas recirculation by the EGR device 50 is increased. Therefore, the intake / exhaust characteristics in the temperature rise control mode are different from the intake / exhaust characteristics in the normal control mode other than the temperature rise control mode.

The turbocharger 40 is a supercharger that compresses the intake air flowing through the intake passage 20 by utilizing the flow of the exhaust gas flowing through the exhaust passage 30. The turbocharger 40 has a turbine 42T provided in the exhaust passage 30 and a compressor 42C provided in the intake passage 20. The turbine 42T has a valve whose opening degree can be controlled. The compressor 42C rotates in conjunction with the rotation of the turbine 42T to compress the intake air.

The EGR device 50 recirculates a part of the exhaust gas to the engine body 10. Specifically, the EGR device 50 uses a part of the exhaust gas (hereinafter referred to as EGR gas) in the exhaust passage 30 (here, the exhaust manifold 32) in the intake passage 20 (here, the intake manifold 22). (Inside). The EGR device 50 includes an EGR passage 52, an EGR cooler 53, an EGR valve 54, and a temperature sensor 55.

The EGR passage 52 is a flow path through which EGR gas flows. The EGR cooler 53 is provided in the EGR passage 52 and cools the EGR gas. The EGR valve 54 is a valve that can be opened and closed, and regulates the flow rate of EGR gas. The temperature sensor 55 detects the temperature of the EGR gas flowing through the EGR passage 52.

The control device 100 controls the operation of the entire internal combustion engine 1. The control device 100 controls the opening degree of the turbocharger 40 and the intake throttle valve 28 to perform supercharging control for controlling the supercharging pressure of the air flowing to the engine body 10. For example, the control device 100 performs feedforward control or feedback control by the turbocharger 40 or feedback control by the intake throttle valve 28 as supercharging control.

Further, the control device 100 performs feedback control by the intake throttle valve 28 in the above-mentioned temperature rise control mode. When the feedback control is started, the intake throttle valve 28 closes to the target opening degree so as to reduce the intake amount of fresh air. On the other hand, when the feedback control is stopped, the intake throttle valve 28 opens to the target opening degree so as to increase the intake amount of fresh air.

In the present embodiment, the control device 100 will be described in detail later, but in the temperature rise control mode, the transition time (open transition time) when the intake throttle valve 28 is opened and the intake throttle valve 28 are closed. The transition time (closed transition time) at the time of performing can be set separately. Then, the control device 100 controls the operating speed of the intake throttle valve 28 according to the set open transition time and closed transition time. As a result, the intake throttle valve 28 can be opened and closed at the transition time suitable for each situation at the start and stop of the feedback control, so that a problem occurs due to the opening and closing of the intake throttle valve 28 in the temperature rise control mode. Can be suppressed.

FIG. 2 is a schematic diagram for explaining the transition time when the intake throttle valve 28 is opened and closed. FIG. 2A shows the transition time according to the comparative example, and FIG. 2B shows the transition time according to the present embodiment. In FIGS. 2 (a) and 2 (b), the closed transition time T1 and the open transition time T2 of the intake throttle valve 28 are shown. In the comparative example shown in FIG. 2A, the closed transition time T1 and the open transition time T2 are the same time, and the speed at which the intake throttle valve 28 closes and the speed at which the intake throttle valve 28 opens are the same. Is.
On the other hand, in the present embodiment shown in FIG. 2B, the open transition time T2 is shorter than the closed transition time T1, and the speed at which the intake throttle valve 28 opens is the intake throttle valve. 28 is faster than the speed at which the closing operation is performed. As a result, the intake throttle valve 28 closes slowly at the start of the feedback control in the temperature rise control mode, and the engine body 10 misfires (more specifically, the temperature rises) due to lack of fresh air caused by the sudden closing. In the control mode, the EGR gas flowing into the engine body 10 is delayed to compensate for the lack of fresh air, so that the amount of oxygen in the engine body 10 is insufficient and the engine misfires). Further, when the feedback control in the temperature rise control mode is stopped, the intake throttle valve 28 suddenly opens, and the acceleration failure of the engine body 10 due to the slow opening can be suppressed.

<Detailed configuration of control device>
The detailed configuration of the control device 100 will be described with reference to FIG.

FIG. 3 is a schematic diagram for explaining the detailed configuration of the control device 100. The control device 100 has a storage unit 110 and a control unit 120.

The storage unit 110 includes, for example, a ROM (Read Only Memory) and a RAM (Random Access Memory). The storage unit 110 stores programs and various data for execution by the control unit 120.

The control unit 120 is, for example, a CPU (Central Processing Unit). The control unit 120 controls the operation of the internal combustion engine 1 by executing the program stored in the storage unit 110. In the present embodiment, the control unit 120 functions as a timing specifying unit 122, an operation direction determination unit 123, a transition time setting unit 124, and a valve control unit 125.

The timing specifying unit 122 specifies the start timing or the stop timing of the feedback control of the boost pressure by the intake throttle valve 28 while the temperature rise control mode for raising the temperature of the aftertreatment device 35 (specifically, the catalyst) is being executed. .. The timing specifying unit 122 specifies the timing when the feedback control is turned on as the start timing, and the timing when the feedback control is turned off as the stop timing.

The timing specifying unit 122 can specify whether the feedback control is on or off based on the detection result of the detection sensor group 70. For example, the timing at which the feedback control is turned on is a condition in which the temperature rise control mode is executed and the operating region (for example, determined by the fuel injection amount and the rotation speed of the engine body 10) is the feedback control region of the intake throttle valve 28. If it meets the requirements. On the other hand, the timing at which the feedback control is turned off is when the above conditions are not satisfied.

The operation direction determination unit 123 determines the opening / closing direction of the intake throttle valve 28 at the start and stop of the feedback control in the temperature rise control mode. That is, the operation direction determination unit 123 determines whether the intake throttle valve 28 opens in the open direction or closes in the closed direction at the start timing or stop timing specified by the timing specifying unit 122. For example, the operating direction determination unit 123 operates the operating direction of the intake throttle valve 28 based on the difference between the opening degree of the intake throttle valve 28 before the transition and the opening degree of the valve after the transition (hereinafter, also referred to as an opening degree difference). Is determined. Here, the opening degree before the start of the transition and the opening degree after the start of the transition depend on the rotation speed of the engine body 10 detected by the detection sensor group 70, the fuel injection amount, the atmospheric pressure, the temperature of the engine cooling water, the temperature of the intake air, and the like. Can be set.

FIG. 4 is a schematic diagram for explaining the determination of the operating direction of the intake throttle valve 28. In FIG. 4A, it is assumed that the opening degree of the intake throttle valve 28 at the start timing is A1 and the target opening degree after the transition of the intake throttle valve 28 is A2. The operation direction determination unit 123 determines that the intake throttle valve 28 closes in the closing direction when the difference between the opening degrees A2 and the opening degree A1 is larger than a predetermined threshold value. On the other hand, the operation direction determination unit 123 determines that the intake throttle valve 28 operates in the open direction when the difference between the opening degrees A2 and the opening degree A1 is equal to or less than the threshold value.

In FIG. 4B, it is assumed that the opening degree of the intake throttle valve 28 at the stop timing is A3, and the target opening degree after the transition of the intake throttle valve 28 is A4. The operation direction determination unit 123 determines that the intake throttle valve 28 opens in the opening direction when the difference between the opening degrees A4 and the opening degree A3 is larger than a predetermined threshold value. On the other hand, the operation direction determination unit 123 determines that the intake throttle valve 28 closes in the closing direction when the difference between the opening degrees A4 and the opening degree A3 is equal to or less than the threshold value. By obtaining the difference in opening degree in this way, the operating direction of the intake throttle valve 28 can be easily detected at the start timing or the stop timing of the feedback control.

The transition time setting unit 124 sets the transition time to the target opening degree in the operation direction of the intake throttle valve 28 according to the operation direction of the intake throttle valve 28 determined by the operation direction determination unit 123. That is, when the operation direction determination unit 123 determines that the intake throttle valve 28 operates in the closing direction, the transition time setting unit 124 closes the intake throttle valve 28 from the opening before the transition to the target opening. Set the closed transition time. When the operation direction determination unit 123 determines that the intake throttle valve 28 operates in the open direction, the transition time setting unit 124 opens the intake throttle valve 28 from the opening before the transition to the target opening. Set the time.

In the present embodiment, the transition time setting unit 124 sets the closed transition time and the open transition time of the intake throttle valve 28 so as to be different. Specifically, the transition time setting unit 124 sets the closed transition time and the open transition time so that the closed transition time is longer than the open transition time. As a result, the time for the intake throttle valve 28 to close is lengthened, and the time for the intake throttle valve 28 to open is shortened.

The valve control unit 125 controls the opening degree of the intake throttle valve 28 in order to control the boost pressure of the air flowing to the engine body 10. The valve control unit 125 controls the opening operation and the closing operation of the intake throttle valve 28 in the temperature rise control mode. The valve control unit 125 changes the operating speed of the intake throttle valve 28 according to the transition time set by the transition time setting unit 124 in the temperature rise control mode.

For example, the valve control unit 125 sets the closing operation speed of the intake throttle valve 28 according to the closed transition time set by the transition time setting unit 124, and the opening operation speed of the intake throttle valve 28 according to the open transition time. To set. Since the closed transition time is set longer than the open transition time, the speed at which the intake throttle valve 28 closes when the feedback control starts is higher than the speed at which the intake throttle valve 28 opens when the feedback control stops. Is also slow. Therefore, at the start of the feedback control, the intake throttle valve 28 is slowly closed, and at that time, oxygen of the EGR gas is sufficiently distributed to the engine body 10, so that misfire of the engine body 10 can be suppressed. Further, when the feedback control is stopped, the intake throttle valve 28 suddenly opens, and the amount of fresh air sucked into the engine body 10 increases, so that acceleration failure of the engine body 10 can be suppressed.

<Effect in this embodiment>
In the control device 100 of the internal combustion engine 1 of the above-described embodiment, whether the intake throttle valve 28 opens in the open direction or closes in the closed direction at the start timing or the stop timing of the feedback control in the temperature rise control mode. Is determined. Then, the control device 100 sets the transition time to the target opening degree in the operating direction of the intake throttle valve 28 according to the determined operating direction of the intake throttle valve 28. That is, the control device 100 separately sets the closed transition time and the open transition time of the intake throttle valve 28.
As a result, the intake throttle valve 28 can be opened and closed at a transition time suitable for each situation after the feedback control in the temperature rise control mode is started and stopped, so that the intake throttle valve 28 can be opened and closed in the temperature rise control mode. It is possible to suppress the occurrence of malfunctions (for example, misfire of the engine body 10 and poor acceleration).

Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes can be made within the scope of the gist. be. For example, all or part of the device can be functionally or physically distributed / integrated in any unit. Also included in the embodiments of the present invention are new embodiments resulting from any combination of the plurality of embodiments. The effect of the new embodiment produced by the combination has the effect of the original embodiment together.

1 Internal combustion engine 10 Engine body 20 Intake passage 28 Intake throttle valve 35 Post-processing device 100 Control device 122 Timing specification unit 123 Operation direction determination unit 124 Transition time setting unit 125 Valve control unit

Claims (5)

A valve control unit that controls the opening of a valve that can be opened and closed in the intake passage to control the boost pressure of the air flowing to the internal combustion engine body.
A timing specifying unit that specifies the start timing or stop timing of the feedback control of the boost pressure by the valve while the temperature rise control mode for raising the temperature of the aftertreatment device that purifies the exhaust gas generated from the internal combustion engine main body is being executed. When,
An operation direction determining unit for determining whether the valve opens in the opening direction or closes in the closing direction at the start timing or the stop timing specified by the timing specifying unit.
A transition time setting unit that sets a transition time to a target opening degree in the operation direction of the valve according to the operation direction of the valve determined by the operation direction determination unit.
A control device for an internal combustion engine. The closing transition time setting unit is such that the closing transition time in which the valve closes to the target opening in the closing direction is longer than the opening transition time in which the valve opens to the target opening in the opening direction. Set the transition time and the open transition time,
The control device for an internal combustion engine according to claim 1. The operating direction determination unit determines the operating direction of the valve based on the difference between the opening degree of the valve before the transition and the opening degree of the valve after the transition.
The control device for an internal combustion engine according to claim 1 or 2. The operation direction determination unit determines that the valve operates in the open direction when the difference is larger than a predetermined threshold value at the stop timing, and when the difference is equal to or less than the threshold value, the operation direction determination unit determines that the valve operates in the open direction. It is determined that the valve closes in the closing direction.
The control device for an internal combustion engine according to claim 3. The operation direction determination unit determines that the valve closes in the closing direction when the difference is larger than a predetermined threshold value at the start timing, and when the difference is equal to or less than the threshold value, the operation direction determination unit determines that the valve operates in the closing direction. It is determined that the valve opens in the opening direction.
The control device for an internal combustion engine according to claim 3 or 4.

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