JP7226406B2 - Control device for internal combustion engine - Google Patents

Description

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

2. Description of the Related Art In an internal combustion engine, the boost pressure of intake air flowing into the internal combustion engine body is adjusted by controlling the opening of a valve provided in an intake passage or a supercharger.
Further, the internal combustion engine is provided with an aftertreatment device (for example, a catalyst) that purifies the exhaust gas, and in order to activate the catalyst, a temperature increase control mode for increasing the temperature of the catalyst is executed. In the temperature increase control mode with less fresh air, feedback control is performed by the valve because the control performance of the boost pressure by the valve is higher than that of the supercharger.

JP 2009-79557 A

By the way, the control region in which the valve performs feedback control is the same as the control region in which the supercharger performs feedforward control. In this case, since there is a region that is not suitable as a control region for feedback control of the valve, which has controllability different from that of the supercharger, there is a case where feedback control of the valve is not performed with high accuracy.

Accordingly, the present invention has been made in view of these points, and an object of the present invention is to perform feedback control of the valve with high precision in the temperature increase control mode.

According to one aspect of the present invention, a supercharging control unit that controls the opening degree of a valve provided in an intake passage and a supercharger to control the supercharging pressure of air flowing to an internal combustion engine main body; In the control region defined by the rotation speed of the main body and the fuel injection amount, a partial region of the supercharger FF region in which the supercharger is feedforward controlled for the supercharging pressure is controlled by the valve FB in which the valve is feedback-controlled. a control region setting unit for setting a region; and a mode determination unit for determining whether or not a temperature increase control mode for increasing the temperature of an aftertreatment device for purifying exhaust gas generated from the internal combustion engine main body is being executed. When the mode determination unit determines that the temperature increase control mode is being executed, the supercharging control unit feeds back the valve within the valve FB region set by the control region setting unit. A controller for an internal combustion engine is provided.

Further, the control region setting unit sets a region in which the fuel injection amount is equal to or greater than a first injection amount and equal to or less than a second injection amount in the supercharger FF region as the valve FB region. good too.

Further, the control region setting unit sets a region in which the number of revolutions is equal to or less than a predetermined number as the valve FB region in the control region, and the supercharging control unit selects the temperature increase control mode by the mode determination unit. is being executed and the number of revolutions is greater than the predetermined number, feedback control of the supercharger may be performed.

Further, the mode determination unit may determine whether or not the temperature increase control mode is set based on the temperature of cooling water for cooling the internal combustion engine and the temperature of the exhaust gas.

ADVANTAGE OF THE INVENTION According to this invention, it is effective in being able to perform feedback control of a valve with high precision at the temperature increase control mode.

1 is a schematic diagram for explaining the configuration of an internal combustion engine 1 according to one embodiment; FIG. FIG. 4 is a schematic diagram for explaining a valve FB area in a temperature increase control mode; 2 is a schematic diagram for explaining the detailed configuration of the control device 100; FIG. FIG. 10 is a schematic diagram for explaining a setting example of a valve FB area in a temperature increase control mode;

<Configuration of Internal Combustion Engine>
A configuration of an internal combustion engine according to one embodiment of the present invention will be described with reference to FIG.

FIG. 1 is a schematic diagram for explaining the configuration of an internal combustion engine 1 according to one 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 a gasoline engine, for example. The internal combustion engine 1 has an engine 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, as shown in FIG.

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

The fuel injection device 15 is an injection device that injects fuel into the combustion chamber inside the engine body 10 . The fuel injector 15 is here a common rail fuel injector and has an injector 16 and a common rail 17 . Injectors 16 inject fuel into the combustion chamber within 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 taken 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 an 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 the cylinders. The intake pipe 23 is provided with an air cleaner 24, an air flow meter 25, a compressor 42C of the turbocharger 40, an intercooler 27, and an intake throttle valve . The airflow meter 25 detects the intake air amount of the internal combustion engine 1 per unit time, that is, the intake flow rate. The opening of the intake throttle valve 28 can be adjusted, for example, by rotating it.

The exhaust passage 30 is a passage through which 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. A turbine 42T of the turbocharger 40 and an aftertreatment device 35 are provided in the exhaust pipe 33 . The post-treatment device 35 is a device for purifying 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 quickly raising the temperature of the aftertreatment device 35 (specifically, the catalyst) from after the cold start of the internal combustion engine 1 to the completion of warm-up (hereinafter referred to as temperature increase control mode). is executable. In the temperature increase control mode, the intake of fresh air is reduced, while the amount of exhaust gas recirculated by the EGR device 50 is increased. Therefore, the intake and exhaust characteristics in the temperature increase control mode differ from the intake and exhaust characteristics in the normal control mode other than the temperature increase control mode.

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

The EGR device 50 recirculates part of the exhaust gas to the engine body 10 . Specifically, the EGR device 50 transfers part of the exhaust gas (hereinafter referred to as EGR gas) in the exhaust passage 30 (here, the exhaust manifold 32) into the intake passage 20 (here, the intake manifold 22). inside) to reflux. The EGR device 50 has 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 adjusts the flow rate of EGR gas. A temperature sensor 55 detects the temperature of EGR gas flowing through the EGR passage 52 .

The control device 100 controls the operation of the internal combustion engine 1 as a whole. The control device 100 controls the opening degrees of the turbocharger 40 and the intake throttle valve 28 to perform supercharging control to control 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 or feedback control by the turbocharger 40 in the temperature increase control mode described above. For example, the control device 100 performs feedback control of the intake throttle valve 28 when the rotation speed of the engine body 10 is low, and performs feedback control of the turbocharger 40 when the rotation speed of the engine body 10 is high.

In the present embodiment, the control device 100 narrows the region in which feedback control of the intake throttle valve 28 is performed (hereinafter referred to as the valve FB region), which will be described later in detail. As a result, the intake throttle valve 28 can be prevented from operating in a region of poor controllability, so feedback control of the intake throttle valve 28 in the temperature increase control mode can be performed with high accuracy.

FIG. 2 is a schematic diagram for explaining the valve FB area in the temperature increase control mode. FIG. 2(a) shows the valve FB area according to the comparative example, and FIG. 2(b) shows the valve FB area according to the present embodiment. 2(a) and 2(b), a region R1 in which the temperature increase control mode is executed, a turbo FF region R2 in which the turbocharger 40 in the temperature increase control mode performs feedforward control, and a valve FB Region R3 is shown. In the comparative example shown in FIG. 2(a), the turbo FF region R2 and the valve FB region R3 overlap. In this case, the valve FB region R3 includes a control region (region with poor controllability) that is not suitable for feedback control of the intake throttle valve . In contrast, in the present embodiment shown in FIG. 2(b), the valve FB region R3 is a partial region of the turbo FF region R2, which is suitable for the intake throttle valve 28 to perform feedback control. Only control regions (regions with good controllability) are included.

<Detailed configuration of control device>
A 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. As shown in FIG. The control device 100 has a storage section 110 and a control section 120 .

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

The control unit 120 is, for example, a CPU (Central Processing Unit). Control unit 120 controls the operation of internal combustion engine 1 by executing a program stored in storage unit 110 . In this embodiment, the control unit 120 functions as a control area setting unit 122, a mode determination unit 123, and a supercharging control unit 124.

A control region setting unit 122 sets a region in which the intake throttle valve 28 is controlled. The control region setting unit 122 sets the control region based on the rotation speed of the engine body 10 and the fuel injection amount detected by the detection sensor group 70 . For example, the control region setting unit 122 sets the valve FB region in which the intake throttle valve 28 is feedback-controlled during the temperature increase control mode. In the control region, the control region setting unit 122 sets a partial region of the turbo FF region (supercharger FF region) in which the turbocharger 40 is feedforward controlled as a valve FB region in which the intake throttle valve 28 is feedback-controlled. .

FIG. 4 is a schematic diagram for explaining a setting example of the valve FB area in the temperature increase control mode. In FIG. 4, the horizontal axis is the rotation speed of the engine body 10, and the vertical axis is the fuel injection amount. The area surrounded by broken lines is the turbo FF area R2, and the hatched area is the valve FB area R3. The valve FB region R3 set by the control region setting unit 122 is a region in which the fuel injection amount is equal to or greater than the first injection amount A1 and equal to or less than the second injection amount A2 within the turbo FF region R2. Further, the valve FB region R3 is a region in which the rotation speed is equal to or higher than the first rotation speed C1 and equal to or lower than the second rotation speed C2. Although not shown in FIG. 4, the region on the side higher than the second rotational speed C2 (ie, the region where the controllability of the intake throttle valve 28 is poor) is the region where the turbocharger 40 performs feedback control. The first injection amount A1 corresponds to the first threshold, and the second injection amount A2 corresponds to the second threshold.

A mode determination unit 123 determines the control mode of the internal combustion engine 1 . For example, the mode determination unit 123 determines whether the control mode is the temperature increase control mode. The temperature increase control mode is a control mode for quickly increasing the temperature of the aftertreatment device 35 (specifically, the catalyst) during the period from the cold start of the internal combustion engine 1 to the completion of warm-up.

The mode determination unit 123 determines the control mode based on the state of the internal combustion engine 1 detected by the detection sensor group 70 . The mode determination unit 123 may determine the control mode based on the temperature of cooling water that cools the internal combustion engine 1 and the temperature of the exhaust gas. For example, when the temperature of the cooling water and the temperature of the exhaust gas are respectively higher than the predetermined values, the mode determination unit 123 determines that the temperature increase control mode is set, and If it is lower than the value, it is determined that it is in the normal control mode. Note that the mode determination unit 123 may determine by including another parameter (for example, the atmospheric pressure) in addition to the temperature of the cooling water and the temperature of the exhaust gas.

The supercharging control unit 124 performs supercharging control of intake air. The supercharging control unit 124 controls the opening degrees of the intake throttle valve 28 provided in the intake passage 20 and the turbocharger 40 (specifically, the valve of the turbine 42T) to supercharge the air flowing to the engine body 10. Control pressure.

The supercharging control unit 124 performs supercharging control, for example, in the temperature increase control mode. Normally, the turbocharger 40 has excellent controllability for a large amount of intake air, and the intake throttle valve 28 has excellent controllability for a small amount of intake air. Therefore, the supercharging control unit 124 performs feedback control of the intake throttle valve 28 in the temperature increase control mode when the rotational speed of the engine body 10 is low (that is, when the amount of intake air is small). On the other hand, the supercharging control unit 124 performs feedback control of the turbocharger 40 in the temperature increase control mode when the rotation speed of the engine body 10 is high (that is, when the amount of intake air is large).

In the temperature increase control mode, the supercharging control unit 124 feedback-controls the intake throttle valve 28 within the valve FB region, which is a partial region of the turbo FF region. That is, when the mode determination unit 123 determines that the temperature increase control mode is being executed, the supercharging control unit 124 operates the intake throttle valve 28 within the valve FB region set by the control region setting unit 122. feedback control. As a result, the intake throttle valve 28 can perform feedback control in a region where controllability is good. Note that the supercharging control unit 124 may perform feedforward control by the turbocharger 40 in a region other than the valve FB region within the turbo FF region.

When mode determination unit 123 determines that the temperature increase control mode is being executed and the number of revolutions is greater than a predetermined number (second number of revolutions C2 shown in FIG. 4), supercharging control unit 124 switches the turbocharger 40 is feedback controlled. That is, the supercharging control unit 124 performs supercharging control by the turbocharger 40 without performing supercharging control by the intake throttle valve 28 . As a result, the turbocharger 40 can appropriately perform supercharging control in areas where the controllability of the intake throttle valve 28 is poor.

<Effects of this embodiment>
The control device 100 for the internal combustion engine 1 of the embodiment described above sets a partial turbo FF region in which the turbocharger 40 is feedforward-controlled as a valve FB region in which the intake throttle valve 28 is feedback-controlled. In the temperature increase control mode, the control device 100 feedback-controls the intake throttle valve 28 within the set valve FB region.
As a result, by limiting the feedback control region of the intake throttle valve 28 to, for example, a low load and low rotation region, it is possible to prevent the intake throttle valve 28 from being controlled in a region with poor controllability. Therefore, feedback control of the intake throttle valve 28 can be performed with higher accuracy.

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 are possible within the scope of the gist thereof. be. For example, all or part of the device can be functionally or physically distributed and integrated in arbitrary units. In addition, new embodiments resulting from arbitrary combinations of multiple embodiments are also included in the embodiments of the present invention. The effect of the new embodiment caused by the combination has the effect of the original embodiment.

Reference Signs List 1 internal combustion engine 20 intake passage 28 intake throttle valve 35 aftertreatment device 40 turbocharger 100 control device 122 control region setting unit 123 mode determination unit 124 supercharging control unit

Claims (4)

a supercharging control unit that controls the opening degree of a valve provided in the intake passage and the supercharger to control the supercharging pressure of the air flowing to the internal combustion engine main body;
In the control region defined by the rotational speed of the internal combustion engine body and the fuel injection amount, a partial region of the supercharger FF region in which the supercharger performs feedforward control of the supercharging pressure is controlled by feedback control of the valve. a control region setting unit that sets the valve FB region for
a mode determination unit that determines whether or not a temperature increase control mode for increasing the temperature of an aftertreatment device for purifying exhaust gas generated from the internal combustion engine main body is being executed;
with
When the mode determination unit determines that the temperature increase control mode is being executed, the supercharging control unit feedback-controls the valve within the valve FB region set by the control region setting unit. ,
A control device for an internal combustion engine. The control region setting unit sets a region in which the fuel injection amount is equal to or greater than a first injection amount and equal to or less than a second injection amount in the turbocharger FF region as the valve FB region.
The control device for an internal combustion engine according to claim 1. The control region setting unit sets a region in which the number of revolutions is a predetermined number or less in the control region as the valve FB region,
The supercharging control unit performs feedback control of the supercharger when the mode determination unit determines that the temperature increase control mode is being executed and the rotational speed is greater than the predetermined number.
A control device for an internal combustion engine according to claim 1 or 2. The mode determination unit determines whether or not the temperature increase control mode is set based on the temperature of cooling water for cooling the internal combustion engine and the temperature of the exhaust gas.
A control device for an internal combustion engine according to any one of claims 1 to 3.

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