Internal combustion engine control device

Abstract

The control device 100 includes a boost pressure control unit 124 that controls the openings of the intake throttle valve 28 and the turbocharger 40, provided in the intake passage, to control the boost pressure of air flowing into the internal combustion engine. A control region setting unit 122 that sets a portion of the turbocharger FF region, which performs feedforward control of the turbocharger 40 on the boost pressure within a control region defined by the engine speed and fuel injection amount, as a valve FB region for feedback control of the intake throttle valve 28. A mode determination unit 123 determines whether a temperature increase control mode is being executed, which increases the temperature of a post-treatment device that purifies exhaust gas generated by the engine. If it is determined that the temperature increase control mode is being executed, the boost pressure control unit 124 performs feedback control of the intake throttle valve 28 within the valve FB region set by the control region setting unit 122.

Description

Technical Field

[0001] The present invention relates to a control device for an internal combustion engine. Background Art

[0002] In an internal combustion engine, the supercharging pressure of intake air flowing into the engine body is adjusted by controlling the opening degree of a valve or a supercharger provided in an intake passage.

[0003] Furthermore, an internal combustion engine is equipped with an aftertreatment device (e.g., a catalyst) that purifies exhaust gas. To activate the catalyst, a temperature increase control mode is implemented to increase the catalyst temperature. In this temperature increase control mode, where there is little fresh air, feedback control is performed using the valve because the control performance of the boost pressure is higher than that of the supercharger.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2009-79557. Summary of the Invention

[0007] Problems to be solved by the invention

[0008] However, the control area where the valve performs feedback control is the same area where the supercharger performs feedforward control. In this case, there is an area that is not suitable for the control area where the valve performs feedback control (the controllability of the valve is different from that of the supercharger), so there are cases where the valve feedback control cannot be performed with high accuracy.

[0009] Therefore, the present invention has been made in view of these problems, and an object of the present invention is to perform feedback control of a valve with high accuracy in a temperature increase control mode.

[0010] Means of solving the problem

[0011] One aspect of the present invention provides a control device for an internal combustion engine, comprising: a boost control unit for controlling the opening of a valve and a supercharger provided in an intake passage, thereby controlling the boost pressure of air flowing to a main body of the internal combustion engine; a control area setting unit for setting a portion of a supercharger FF area in which the supercharger performs feedforward control of the boost pressure within a control area specified by the rotational speed and fuel injection amount of the main body of the internal combustion engine, as a valve FB area in which the valve performs feedback control; and a mode determination unit for determining whether a temperature increase control mode for increasing the temperature of a post-processing device that purifies exhaust gas generated from the main body of the internal combustion engine is being executed, wherein, when the mode determination unit determines that the temperature increase control mode is being executed, the boost control unit causes the valve to perform feedback control within the valve FB area set by the control area setting unit.

[0012] Furthermore, the control region setting unit may set a region in the supercharger FF region where the fuel injection amount is equal to or greater than a first injection amount and equal to or less than a second injection amount as the valve FB region.

[0013] Furthermore, the control region setting unit may set a region where the rotation speed is equal to or higher than a first rotation speed and equal to or lower than a second rotation speed in the supercharger FF region as the valve FB region.

[0014] Furthermore, when the mode determination unit determines that the temperature increase control mode is being executed, the supercharger control unit may perform feedforward control of the supercharger in a region other than the valve FB region within the supercharger FF region.

[0015] In addition, the control area setting unit can also set the area in the control area where the speed is below the specified number as the valve FB area. When the mode judgment unit determines that the temperature rise control mode is being executed and the speed is greater than the specified number, the boost control unit can also cause the supercharger to perform feedback control.

[0016] Furthermore, the mode determination unit may determine whether the temperature increase control mode is selected based on the temperature of cooling water for cooling the internal combustion engine and the temperature of the exhaust gas.

[0017] Effects of the Invention

[0018] According to the present invention, there is an effect of being able to perform feedback control of the valve with high accuracy in the temperature increase control mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram for explaining the structure of the internal combustion engine 1 according to one embodiment.

[0020] Figure 2 It is a schematic diagram for explaining the valve FB region in the temperature increase control mode.

[0021] Figure 3 It is a schematic diagram for explaining the detailed structure of the control device 100 .

[0022] Figure 4 It is a schematic diagram for explaining a setting example of the valve FB region in the temperature increase control mode. DETAILED DESCRIPTION

[0023] <Structure of internal combustion engine>

[0024] Reference Figure 1 The structure of an internal combustion engine according to one embodiment of the present invention will be described.

[0025] Figure 1 1 is a schematic diagram for explaining the structure 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 thereto and may be, for example, a gasoline engine. Figure 1 As shown, the internal combustion engine 1 includes 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 .

[0026] Here, the engine body 10 includes four cylinders 12, but the present invention is not limited thereto. Each cylinder 12 is provided with movable parts such as a piston and a crankshaft.

[0027] The fuel injection device 15 is an injection device that injects fuel into the combustion chamber in the engine body 10. Here, the fuel injection device 15 is a common rail fuel injection device having injectors 16 and a common rail 17. The injectors 16 inject fuel into the combustion chamber in each cylinder 12. The common rail 17 stores the fuel injected from the injectors 16 in a high-pressure state.

[0028] The intake passage 20 is the passage through which intake air drawn into the engine body 10 flows. The intake passage 20 includes 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 the intake air sent from the intake pipe 23 to the intake ports of each cylinder. The intake pipe 23 is equipped with an air filter 24, an air flow meter 25, the compressor 42C of the turbocharger 40, an intercooler 27, and an intake throttle valve 28. The air flow meter 25 detects the amount of air taken into the internal combustion engine 1 per unit time, i.e., the intake air flow rate. The intake throttle valve 28 can be rotated to adjust its opening, for example.

[0029] The exhaust passage 30 is a passage through which exhaust gas generated by the engine main body 10 flows. The exhaust passage 30 includes an exhaust manifold 32 connected to the engine main body 10 and an exhaust pipe 33 connected to the downstream end of the exhaust manifold 32. The exhaust manifold 32 collects exhaust gas sent from the exhaust ports of each cylinder. The exhaust pipe 33 is provided with a turbine 42T of the turbocharger 40 and a post-processing device 35. The post-processing 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.

[0030] However, from the time the internal combustion engine 1 is cold started until the warm-up period is complete, a control mode (hereinafter referred to as the temperature increase control mode) can be executed to prematurely increase the temperature of the aftertreatment device 35 (specifically, the catalyst). In the temperature increase control mode, while reducing the intake of fresh air, 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 those in normal control modes other than the temperature increase control mode.

[0031] The turbocharger 40 is a supercharger that compresses the intake air flowing through the intake passage 20 by utilizing the flow of exhaust gas flowing through the exhaust passage 30. The turbocharger 40 includes a turbine 42T disposed in the exhaust passage 30 and a compressor 42C disposed in the 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, compressing the intake air.

[0032] The EGR device 50 recirculates a portion of the exhaust gas to the engine body 10. Specifically, the EGR device 50 recirculates a portion of the exhaust gas (hereinafter referred to as EGR gas) within the exhaust passage 30 (herein, within the exhaust manifold 32) into the intake passage 20 (herein, within the intake manifold 22). The EGR device 50 includes an EGR passage 52, an EGR cooler 53, an EGR valve 54, and a temperature sensor 55.

[0033] The EGR passage 52 is a flow path through which EGR gas flows. An EGR cooler 53 is provided in the EGR passage 52 to cool the EGR gas. An EGR valve 54 is an openable and closable valve that regulates the flow rate of the EGR gas. A temperature sensor 55 detects the temperature of the EGR gas flowing in the EGR passage 52.

[0034] The control device 100 controls the overall operation of the internal combustion engine 1. The control device 100 controls the openings of the turbocharger 40 and the intake throttle valve 28 to perform supercharging control to control the boost pressure of air flowing into the engine body 10. For example, as supercharging control, the control device 100 performs feedforward control or feedback control of the turbocharger 40, or performs feedback control of the intake throttle valve 28.

[0035] Furthermore, in the temperature increase control mode, the control device 100 performs feedback control of the intake throttle valve 28 or feedback control of the turbocharger 40. For example, when the rotation speed of the engine main body 10 is low, the control device 100 performs feedback control of the intake throttle valve 28, and when the rotation speed of the engine main body 10 is high, the control device 100 performs feedback control of the turbocharger 40.

[0036] In this embodiment, the control device 100 sets a narrow range (hereinafter referred to as the valve FB range) within which feedback control of the intake throttle valve 28 is performed. Details will be described later. This prevents the intake throttle valve 28 from operating in a range with poor controllability, enabling highly accurate feedback control of the intake throttle valve 28 during the temperature increase control mode.

[0037] Figure 2 It is a schematic diagram for explaining the valve FB region in the temperature increase control mode. Figure 2(a) shows the valve FB region according to the comparative example, Figure 2 (b) shows the valve FB region according to this embodiment. Figure 2 (a) and Figure 2 (b) shows the region R1 in which the temperature rise control mode is executed, the turbine FF region R2 in which the turbocharger 40 performs feedforward control during the temperature rise control mode, and the valve FB region R3. Figure 2 In the comparative example shown in (a), the turbine FF region R2 and the valve FB region R3 overlap. In this case, the valve FB region R3 includes a control region (a region with poor controllability) that is not suitable for feedback control of the intake throttle valve 28. Figure 2 In the present embodiment shown in (b), the valve FB region R3 is a partial region of the turbine FF region R2 and includes only a control region (region with good controllability) suitable for feedback control of the intake throttle valve 28 .

[0038] <Detailed Structure of Control Device>

[0039] Reference Figure 2 The detailed structure of the control device 100 will be described.

[0040] Figure 3 1 is a schematic diagram for explaining the detailed configuration of the control device 100. The control device 100 includes a storage unit 110 and a control unit 120.

[0041] The storage unit 110 includes, for example, a ROM (Read Only Memory) and a RAM (Random Access Memory) and stores programs executed by the control unit 120 and various data.

[0042] 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 a program stored in the storage unit 110. In this embodiment, the control unit 120 functions as a control region setting unit 122, a mode determination unit 123, and a supercharging control unit 124.

[0043] The control region setting unit 122 sets the region for controlling the intake throttle valve 28. The control region setting unit 122 sets the control region based on the engine body 10 rotational speed 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 for feedback control of the intake throttle valve 28 during the temperature increase control mode. The control region setting unit 122 sets a portion of the turbine FF region (supercharger FF region) within the control region for feedforward control of the turbocharger 40 as the valve FB region for feedback control of the intake throttle valve 28.

[0044] Figure 4 This is a schematic diagram for explaining an example of setting the valve FB region in the temperature rise control mode. Figure 4 In FIG, 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 the dotted line is the turbine FF area R2, and the hatched area is the valve FB area R3. The valve FB area R3 set by the control area setting unit 122 is an area in which the fuel injection amount in the turbine FF area R2 is greater than the first injection amount A1 and less than the second injection amount A2. In addition, the valve FB area R3 is an area in which the rotation speed is greater than the first rotation speed C1 and less than the second rotation speed C2. In addition, although not in FIG. Figure 4 , the region above the second rotational speed C2 (i.e., 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 value, and the second injection amount A2 corresponds to the second threshold value.

[0045] The 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 rapidly increasing the temperature of the post-treatment device 35 (specifically, the catalyst) between the cold start and the completion of the warm-up of the internal combustion engine 1.

[0046] 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 can determine the control mode based on the temperature of the cooling water used to cool the internal combustion engine 1 and the temperature of the exhaust gas. For example, the mode determination unit 123 determines that the control mode is the heating control mode if the cooling water temperature and the exhaust gas temperature are both higher than predetermined values, and determines that the control mode is the normal control mode if the cooling water temperature and the exhaust gas temperature are both lower than predetermined values. Furthermore, the mode determination unit 123 can also include other parameters (such as atmospheric pressure) in its determination in addition to the cooling water temperature and the exhaust gas temperature.

[0047] The supercharging control unit 124 controls the supercharging pressure of the intake air by controlling the opening of the intake throttle valve 28 and the turbocharger 40 (specifically, the valve of the turbine 42T) provided in the intake passage 20 .

[0048] The boost control unit 124 performs boost control, for example, in the temperature rise control mode. Generally, the turbocharger 40 excels in controllability of large intake air flows, while the intake throttle valve 28 excels in controllability of small intake air flows. Therefore, in the temperature rise control mode, the boost control unit 124 performs feedback control of the intake throttle valve 28 when the engine body 10 speed is low (i.e., when the intake air flow is small). On the other hand, in the temperature rise control mode, the boost control unit 124 performs feedback control of the turbocharger 40 when the engine body 10 speed is high (i.e., when the intake air flow is large).

[0049] During the temperature increase control mode, the supercharge control unit 124 performs feedback control on the intake throttle valve 28 within the valve FB region, which is part of the turbine FF region. Specifically, if the mode determination unit 123 determines that the temperature increase control mode is being executed, the supercharge control unit 124 performs feedback control on the intake throttle valve 28 within the valve FB region set by the control region setting unit 122. This allows the intake throttle valve 28 to be feedback controlled within a region with good controllability. Furthermore, the supercharge control unit 124 can also perform feedforward control of the turbocharger 40 in regions other than the valve FB region within the turbine FF region.

[0050] When the mode determination unit 123 determines that the temperature rise control mode is being executed and the rotation speed is greater than the predetermined number ( Figure 4 When the second speed (C2) shown in FIG. 2 is high, the boost control unit 124 causes the turbocharger 40 to perform feedback control. That is, the boost control unit 124 does not perform boost control by the intake throttle valve 28, but performs boost control by the turbocharger 40. As a result, in the region where the controllability of the intake throttle valve 28 is poor, the turbocharger 40 can appropriately perform boost control.

[0051] <Effects of this embodiment>

[0052] The control device 100 of the internal combustion engine 1 in the above-described embodiment sets a portion of the turbine FF region, in which the turbocharger 40 is subjected to feedforward control, as the valve FB region, in which the intake throttle valve 28 is subjected to feedback control. Then, in the temperature increase control mode, the control device 100 performs feedback control on the intake throttle valve 28 within the set valve FB region.

[0053] Thus, by limiting the feedback control region of the intake throttle valve 28 to, for example, the low load and low rotation speed region, it is possible to suppress control of the intake throttle valve 28 in a region with poor controllability.

[0054] While the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and alterations can be made within the scope of its main purpose. For example, all or part of the device can be functionally or physically dispersed or combined in arbitrary units. In addition, new embodiments generated by any combination of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiments generated by the combination have the effects of the original embodiments.

[0055] Reference numerals

[0056] 1 Internal combustion engine

[0057] 20 Intake passage

[0058] 28 intake throttle valve

[0059] 35 post-processing device

[0060] 40 turbochargers

[0061] 100 control devices

[0062] 122 Control area setting unit

[0063] 123 mode determination unit

[0064] 124 boost control unit

Claims

1. A control device for an internal combustion engine, comprising: a supercharging control unit for controlling the opening of a valve and a supercharger provided in an intake passage, thereby controlling the supercharging pressure of air flowing into the internal combustion engine body; a control region setting unit for setting, as a valve FB region for performing feedback control of the valve, a region in which the fuel injection amount is greater than or equal to a first injection amount and less than or equal to a second injection amount and the speed is greater than or equal to the first speed and less than or equal to the second speed, within a supercharger FF region in which the supercharger performs feedforward control of the supercharging pressure within a control region defined by the speed of the internal combustion engine body and the fuel injection amount; and a mode determination unit for determining whether a temperature increase control mode for increasing the temperature of a post-processing device that purifies exhaust gas generated from the internal combustion engine body is being executed; When the mode determination unit determines that the temperature increase control mode is being executed, the pressure increase control unit causes the valve to perform feedback control within the valve FB region set by the control region setting unit.

2. The control device for an internal combustion engine according to claim 1, wherein: When the mode determination unit determines that the temperature increase control mode is being executed, the supercharger control unit causes the supercharger to perform feedforward control in a region other than the valve FB region within the supercharger FF region.

3. The control device for an internal combustion engine according to claim 1, wherein: The control region setting unit sets a region in the control region where the rotation speed is equal to or less than a predetermined number as the valve FB region. The supercharge control unit performs feedback control on the supercharger when the mode determination unit determines that the temperature increase control mode is being executed and the rotation speed is greater than the predetermined number.

4. The control device for an internal combustion engine according to claim 1, wherein: The mode determination unit determines whether the temperature increase control mode is selected based on the temperature of cooling water for cooling the internal combustion engine and the temperature of the exhaust gas.

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