Internal combustion engine control device

Abstract

To improve the estimation accuracy of pump loss of an internal combustion engine.SOLUTION: An internal combustion engine 10 for which a control device 70 is employed comprises a cylinder 11, a supercharger 30, an intake passage 16, a throttle valve 17 and an exhaust passage 20. The supercharger 30 has a turbine wheel 31, a compressor wheel 32 and a waste gate valve 34. A CPU 71 of the control device 70 performs loss estimation processing which calculates an estimated value of a pump loss of the internal combustion engine 10 on the basis of an intake pressure being the pressure of a portion of the intake passage 16 that is located downstream of the throttle valve 17, an engine rotation number of the internal combustion engine 10, and a supercharge pressure.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an internal combustion engine control device that is applied to an internal combustion engine equipped with a supercharger. [Background technology]

[0002] Patent Document 1 discloses a control device applied to an internal combustion engine equipped with an exhaust-driven supercharger. The control device executes a calculation process for calculating a pumping loss of the internal combustion engine. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-140724 A Summary of the Invention [Problem to be solved by the invention]

[0004] When the turbocharger has a wastegate valve, the control device can control the boost pressure by adjusting the opening of the wastegate valve. When the opening of the wastegate valve is changed, the turbine upstream pressure, which is the exhaust pressure in the exhaust passage of the internal combustion engine upstream of the installation position of the turbine wheel of the turbocharger, changes. When the turbine upstream pressure changes, the pumping loss of the internal combustion engine changes. [Means for solving the problem]

[0005] An internal combustion engine control device for solving the above problems is applied to an internal combustion engine including a cylinder, a supercharger, an intake passage through which air to be introduced into the cylinder flows, a throttle valve installed in the intake passage, and an exhaust passage through which exhaust gas discharged from the inside of the cylinder flows. The supercharger is provided in the exhaust passage and has a turbine wheel that rotates due to the flow of exhaust gas flowing through the exhaust passage, a compressor wheel that is provided in a portion of the intake passage upstream of the throttle valve and rotates in synchronization with the turbine wheel, and a wastegate valve that adjusts the flow rate of exhaust gas that bypasses the turbine wheel out of the exhaust gas flowing through the exhaust passage. The internal combustion engine control device includes an execution device. The execution device is An estimated value of a pumping loss of the internal combustion engine, Intake pressure, which is the pressure of air in the portion of the intake passage downstream of the throttle valve The lower the , and The engine speed of the internal combustion engine The higher the , and Boost pressure The higher the value, the larger the calculation.

[0006] As a result of experiments and simulations, the inventors of the present invention found that there is a correlation between the turbocharger pressure and the turbine upstream pressure, which is the exhaust pressure in the portion of the exhaust passage upstream of the turbine wheel. In other words, when the turbocharger pressure changes due to a change in the opening of the wastegate valve, the turbine upstream pressure also changes.

[0007] Therefore, the above-mentioned internal combustion engine control device calculates an estimate of the pumping loss of the internal combustion engine based on the supercharging pressure, which is correlated with the turbine upstream pressure, in addition to the intake pressure and engine speed. As a result, when the turbine upstream pressure changes, the estimated value of the pumping loss changes because the supercharging pressure has changed. Therefore, the above-mentioned internal combustion engine control device can improve the accuracy of estimating the pumping loss. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a configuration diagram showing an outline of a control device which is an embodiment of an internal combustion engine control device, and an internal combustion engine to which the control device is applied. [Diagram 2] FIG. 2 is a block diagram showing various processes executed by the CPU of the control device. [Diagram 3] FIG. 3 is a timing chart showing the correlation between the supercharging pressure and the turbine upstream pressure. [Figure 4] FIG. 4 is a graph showing the relationship between the required boost pressure and the pumping loss of the internal combustion engine. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, one embodiment of an internal combustion engine control device will be described with reference to Figs. 1 illustrates an internal combustion engine 10 and a control device 70 that controls the operation of the internal combustion engine 10. The control device 70 corresponds to the "internal combustion engine control device."

[0010] <Internal combustion engine> The internal combustion engine 10 includes a plurality of cylinders 11 and a crankshaft 12. Fig. 1 shows only one of the plurality of cylinders 11. Pistons 13 are housed in the plurality of cylinders 11. The plurality of pistons 13 are each connected to the crankshaft 12 via a connecting rod 14. The plurality of pistons 13 reciprocate in the cylinders 11, causing the crankshaft 12 to rotate.

[0011] The internal combustion engine 10 includes an intake passage 16 and a throttle valve 17 installed in the intake passage 16. The intake passage 16 is a passage through which air flows to be introduced into the multiple cylinders 11. The throttle valve 17 is an electronically controlled valve that adjusts the amount of air flowing through the intake passage 16. The larger the opening of the throttle valve 17, the greater the flow rate of air flowing through the intake passage 16.

[0012] The internal combustion engine 10 includes a plurality of fuel injection valves 18, a plurality of ignition devices 19, and an exhaust passage 20. A fuel injection valve 18 and an ignition device 19 are provided for each of a plurality of cylinders 11. The plurality of fuel injection valves 18 inject fuel to be introduced into the cylinders 11. In the plurality of cylinders 11, an air-fuel mixture containing air and fuel is burned by ignition of the ignition device 19. Exhaust gas generated by the combustion of the air-fuel mixture is discharged from inside the cylinders 11 to the exhaust passage 20. In other words, the exhaust passage 20 is a passage through which the exhaust gas discharged from inside the plurality of cylinders 11 flows.

[0013] The internal combustion engine 10 includes an exhaust-driven turbocharger 30. The turbocharger 30 includes a turbine wheel 31, a compressor wheel 32, and a wastegate valve 34. The turbine wheel 31 is provided in the exhaust passage 20. The compressor wheel 32 is provided in a portion of the intake passage 16 upstream of the throttle valve 17. The compressor wheel 32 is connected to the compressor wheel 32 via a connecting shaft 33. Therefore, when the turbine wheel 31 rotates due to the flow of exhaust gas flowing through the exhaust passage 20, the compressor wheel 32 rotates in synchronization with the turbine wheel 31. As a result, the air flowing through the intake passage 16 is compressed.

[0014] The wastegate valve 34 is a valve that adjusts the flow rate of exhaust gas that bypasses the turbine wheel 31. The larger the opening of the wastegate valve 34, the greater the flow rate of exhaust gas that bypasses the turbine wheel 31. As a result, the boost pressure generated by driving the turbocharger 30 becomes lower.

[0015] <Control device> The control device 70 receives detection signals from a plurality of sensors. The sensors include, for example, an accelerator opening sensor 51, a crank angle sensor 52, an air flow meter 53, a supercharging pressure sensor 54, an intake pressure sensor 55, and an atmospheric pressure sensor 56. The accelerator opening sensor 51 detects the amount of operation of the accelerator pedal 101. The amount of operation based on the detection value of the accelerator opening sensor 51 is called the "accelerator opening AC." The crank angle sensor 52 detects the rotation angle of the crankshaft 12. The rotation speed of the crankshaft 12 based on the detection value of the crank angle sensor 52 is called the "engine speed NE." The air flow meter 53 detects the flow rate of air flowing through the intake passage 16. The flow rate of air based on the detection value of the air flow meter 53 is called the "intake air amount GA." The supercharging pressure sensor 54 detects the pressure of air in a portion of the intake passage 16 downstream of the compressor wheel 32 and upstream of the throttle valve 17. The air pressure based on the detection value of the boost pressure sensor 54 is referred to as the "boost pressure PB." The intake pressure sensor 55 detects the air pressure in a portion of the intake passage 16 downstream of the throttle valve 17. The air pressure based on the detection value of the intake pressure sensor 55 is referred to as the "intake pressure PM." The atmospheric pressure sensor 56 detects the atmospheric pressure. The atmospheric pressure based on the detection value of the atmospheric pressure sensor 56 is referred to as the "atmospheric pressure KPA."

[0016] The control device 70 controls the opening of the throttle valve 17, the fuel injection amount of the fuel injection valve 18, the ignition timing of the ignition device 19, and the opening of the wastegate valve 34 based on detection signals from the various sensors described above.

[0017] The control device 70 includes a CPU 71 and a memory 72. The CPU 71 corresponds to an “execution device.” The memory 72 stores various control programs that the CPU 71 executes.

[0018] As shown in FIG. 2, the CPU 71 executes a control program to execute a required value setting process M1, a required value leveling process M3, an opening degree adjustment process M5, an intake pressure acquisition process M7, a normalization process M9, and a loss estimation process M11.

[0019] In the required value setting process M1, the CPU 71 sets a required boost pressure PBRq, which is a required value of the boost pressure PB. Specifically, in the required value setting process M1, the CPU 71 sets a larger value as the required boost pressure PBRq as the larger the required value of the output torque for the internal combustion engine 10 is. When the driver of the vehicle is operating the accelerator pedal 101, the larger the accelerator opening AC is, the larger the required value of the output torque for the internal combustion engine 10 is. Therefore, for example, the larger the accelerator opening AC is, the larger the value as the required boost pressure PBRq is set.

[0020] In the request value leveling process M3, the CPU 71 calculates a required boost pressure smoothed value PBRqLv, which is a value obtained by smoothing the required boost pressure PBRq. For example, in the request value leveling process M3, the CPU 71 calculates a moving average of a plurality of consecutive required boost pressures PBRq in a time series as the required boost pressure smoothed value PBRqLv.

[0021] In the opening degree adjustment process M5, the CPU 71 adjusts the opening degree of the wastegate valve 34 based on the required boost pressure PBRq. For example, the CPU 71 operates the wastegate valve 34 to adjust the opening degree so that the higher the required boost pressure PBRq, the smaller the opening degree becomes.

[0022] The CPU 71 acquires the intake pressure PM in the intake pressure acquisition process M7. In normalization processing M9, the CPU 71 normalizes the intake pressure PM and the required boost pressure smoothed value PBRqLv by the atmospheric pressure KPA. Specifically, the CPU 71 normalizes the intake pressure PM by dividing the intake pressure PM by the atmospheric pressure KPA. The intake pressure normalized by the atmospheric pressure KPA is referred to as the "normalized intake pressure PMa." The CPU 71 also normalizes the required boost pressure smoothed value PBRqLv by dividing the required boost pressure smoothed value PBRqLv by the atmospheric pressure KPA. The required boost pressure smoothed value normalized by the atmospheric pressure KPA is referred to as the "normalized required boost pressure smoothed value PBRqLva."

[0023] In a loss estimation process M11, the CPU 71 calculates an estimated value TqPLE of a pumping loss of the internal combustion engine 10 based on the intake pressure PM, the engine speed NE, and the boost pressure PB. In this embodiment, the CPU 71 calculates the estimated value TqPLE of the pumping loss based on the normalized intake pressure PMa, the engine speed NE, and the normalized required boost pressure smoothed value PBRqLva. In the loss estimation process M11, the CPU 71 calculates the estimated value TqPLE of the pumping loss by using a map MP.

[0024] The map MP is a map for calculating a value corresponding to the intake air pressure, the engine speed, and the boost pressure as the estimated pumping loss TqPLE. The map MP is created as follows. The lower the intake pressure, the larger the estimated pump loss TqPLE. The higher the engine speed, the larger the estimated pump loss TqPLE. The higher the boost pressure, the larger the estimated pump loss TqPLE becomes.

[0025] In this embodiment, the CPU 71 calculates a value according to the normalized intake pressure PMa, the engine speed NE, and the normalized required boost pressure smoothed value PBRqLva using the map MP, and sets the calculated value as the estimated value TqPLE of the pumping loss.

[0026] Here, the relationship between the turbine upstream pressure PEX and the boost pressure will be described with reference to FIG. 3. The turbine upstream pressure PEX is the exhaust pressure in the portion of the exhaust passage 20 upstream of the turbine wheel 31. FIG. 3(A) shows the transition of the turbine upstream pressure PEX, and FIG. 3(B) shows the transition of the boost pressure. In FIG. 3(B), the thin solid line shows the transition of the required boost pressure PBRq, the thick solid line shows the transition of the required boost pressure smoothing value PBRqLv, and the dashed line shows the transition of the boost pressure PB, which is the detection value of the boost pressure sensor 54. As shown in FIG. 3, as the required boost pressure smoothing value PBRqLv becomes lower, the turbine upstream pressure PEX becomes lower. That is, FIG. 3 shows that there is a correlation between the boost pressure and the turbine upstream pressure PEX.

[0027] 4 is a graph showing the change in the pumping loss TqPL when the required boost pressure PBRq is changed under the condition that the intake pressure PM is constant. As is clear from FIG. 4, the pumping loss TqPL increases as the required boost pressure PBRq increases.

[0028] <Actions and Effects of the Present Embodiment> (1) When the required boost pressure PBRq changes and the turbine upstream pressure PEX changes, the pumping loss TqPL changes. As shown in Fig. 4, the higher the required boost pressure PBRq, the larger the pumping loss TqPL becomes.

[0029] In this embodiment, the control device 70 calculates the pumping loss estimate value TqPLE based on the required boost pressure PBRq in addition to the intake pressure and engine speed. As a result, if the turbine upstream pressure PEX changes, the required boost pressure PBRq also changes, and therefore the pumping loss estimate value TqPLE changes. Therefore, the control device 70 can improve the accuracy of estimating the pumping loss.

[0030] (2) When the accelerator opening AC changes suddenly, the required boost pressure PBRq changes significantly. Figure 3(B) shows the transition of the required boost pressure PBRq when the accelerator opening AC suddenly decreases. In such a case, there is a risk of a deviation between the required boost pressure PBRq and the actual boost pressure. If the required boost pressure PBRq is used to calculate the pumping loss estimate TqPLE in a situation where a deviation occurs between the required boost pressure PBRq and the actual boost pressure, it is difficult to say that the accuracy of the pumping loss estimate is high.

[0031] Here, even if the accelerator opening AC changes suddenly as shown in Fig. 3B, the required boost pressure smoothed value PBRqLv changes gradually. In other words, even if the accelerator opening AC changes suddenly, a deviation is unlikely to occur between the required boost pressure smoothed value PBRqLv and the actual value of the boost pressure.

[0032] Furthermore, when the required boost pressure PBRq changes suddenly, the boost pressure PB, which is the detection value of the boost pressure sensor 54, may fluctuate as shown by the dashed line in FIG. 3(B). Therefore, the control device 70 calculates the estimated value TqPLE of the pumping loss based on the required boost pressure smoothed value PBRqLv obtained by leveling the required boost pressure PBRq. This allows the control device 70 to suppress a decrease in the accuracy of estimating the pumping loss when the required boost pressure PBRq changes significantly.

[0033] (3) The control device 70 calculates the estimated value TqPLE of the pumping loss using the normalized intake pressure PMa, which is the intake pressure normalized by the atmospheric pressure KPA. Similarly, the control device 70 calculates the estimated value TqPLE of the pumping loss using the normalized required boost pressure smoothed value PBRqLva, which is the required boost pressure smoothed value PBRqLv normalized by the atmospheric pressure KPA. Therefore, the control device 70 can suppress a decrease in the estimation accuracy of the pumping loss caused by a change in the atmospheric pressure KPA.

[0034] (4) Even if the internal combustion engine is not provided with a sensor for detecting the turbine upstream pressure PEX, the control device 70 can calculate a value that reflects a change in the turbine upstream pressure PEX as the estimated value TqPLE of the pumping loss.

[0035] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

[0036] It is not essential to use the intake pressure normalized by the atmospheric pressure KPA when calculating the estimated value TqPLE of the pumping loss. That is, the control device 70 may calculate the estimated value TqPLE by using the intake pressure PM instead of the normalized intake pressure PMa.

[0037] It is not essential to use the smoothed required boost pressure value PBRqLv normalized by the atmospheric pressure KPA when calculating the estimated pumping loss value TqPLE. That is, the control device 70 may calculate the estimated value TqPLE using the smoothed required boost pressure value PBRqLv instead of the normalized smoothed required boost pressure value PBRqLva.

[0038] The estimated pumping loss TqPLE may be calculated using the boost pressure PB based on the detection value of the boost pressure sensor 54, instead of the required boost pressure PBRq. In this case, it is preferable to use an averaged value of the boost pressure PB.

[0039] If the pumping loss estimate TqPLE is calculated based on the boost pressure, engine speed, and boost pressure, the map MP described above does not need to be used. For example, the control device 70 calculates a base value of the pumping loss based on the boost pressure and engine speed. The control device 70 also calculates a correction value of the pumping loss based on the boost pressure. At this time, the control device 70 calculates a larger value as the correction value as the boost pressure PB is higher. The control device 70 then calculates the sum of the base value and the correction value as the pumping loss estimate TqPLE. Even if the pumping loss estimate TqPLE is calculated in this manner, it is possible to calculate the pumping loss estimate TqPLE as a value that reflects a change in the turbine upstream pressure PEX.

[0040] In the above-described intake pressure acquisition process M7, a value based on the detection value of the intake pressure sensor 55 is acquired as the intake pressure PM, but this is not limiting. For example, the intake pressure acquisition process M7 may be a process for acquiring an estimated value of the intake pressure derived using a physical model of the intake system of the internal combustion engine 10 as the intake pressure PM.

[0041] The control device 70 is not limited to a device having a CPU and a ROM and executing software processing. That is, the control device 70 may have any one of the following configurations (a) to (c). (a) The control device 70 includes one or more processors that execute various processes according to a computer program. The processor includes a CPU and memory such as RAM and ROM. The memory stores program codes or instructions that are configured to cause the CPU to execute processes. The memory, i.e., computer-readable media, includes any available media that can be accessed by a general-purpose or special-purpose computer.

[0042] (b) The control device 70 includes one or more dedicated hardware circuits for executing various processes. Examples of the dedicated hardware circuits include application specific integrated circuits, i.e., ASIC and FPGA. ASIC is an abbreviation for "Application Specific Integrated Circuit" and FPGA is an abbreviation for "Field Programmable Gate Array."

[0043] (c) The control device 70 includes a processor that executes some of the various processes in accordance with a computer program, and a dedicated hardware circuit that executes the remaining processes among the various processes.

[0044] <Technical philosophy> Next, the technical ideas that can be understood from the above embodiment and modified examples will be described. (Technical Idea 1) An internal combustion engine control device applied to an internal combustion engine having a cylinder, a supercharger, an intake passage through which air to be introduced into the cylinder flows, a throttle valve installed in the intake passage, and an exhaust passage through which exhaust gas discharged from inside the cylinder flows, the turbocharger is provided in the exhaust passage and has a turbine wheel that rotates due to the flow of exhaust gas flowing through the exhaust passage, a compressor wheel that is provided in a portion of the intake passage upstream of the throttle valve and rotates in synchronization with the turbine wheel, and a wastegate valve that adjusts the flow rate of exhaust gas that bypasses the turbine wheel out of the exhaust gas flowing through the exhaust passage, The internal combustion engine control device includes an execution device, The execution device executes a loss estimation process to calculate an estimate of a pumping loss of the internal combustion engine, based on an intake pressure, which is the pressure of air in a portion of the intake passage downstream of the throttle valve, an engine speed of the internal combustion engine, and a boost pressure.

[0045] (Technical idea 2) The execution device is a required value setting process for setting a required boost pressure, which is a required value of the boost pressure, to a larger value as a required value of an output torque of the internal combustion engine increases; an opening adjustment process for adjusting an opening of the wastegate valve so that the opening of the wastegate valve becomes smaller as the required boost pressure increases; and a leveling process for calculating a required boost pressure smoothed value, which is a leveled value of the required boost pressure. The internal combustion engine control device according to Technical Concept 1, wherein the boost pressure used in the loss estimation process is an averaged value of the required boost pressure.

[0046] (Technical Concept 3) The internal combustion engine control device according to Technical Concept 1 or 2, wherein the intake pressure used in the loss estimation process is a value normalized with atmospheric pressure. [Explanation of symbols]

[0047] 10. Internal combustion engine 11…Cylinder 16…Intake passage 17...Throttle valve 20…Exhaust passage 30…Supercharger 31...Turbine wheel 32…Compressor wheel 34…Wastegate valve 70...Control device 71…CPU

Claims

1. An internal combustion engine control device that is applied to an internal combustion engine that includes a cylinder, a supercharger, an intake passage through which air to be introduced into the cylinder flows, a throttle valve installed in the intake passage, and an exhaust passage through which exhaust gas discharged from inside the cylinder flows, the turbocharger is provided in the exhaust passage and has a turbine wheel that rotates due to the flow of exhaust gas flowing through the exhaust passage, a compressor wheel that is provided in a portion of the intake passage upstream of the throttle valve and rotates in synchronization with the turbine wheel, and a wastegate valve that adjusts the flow rate of exhaust gas that bypasses the turbine wheel out of the exhaust gas flowing through the exhaust passage, The internal combustion engine control device includes an execution device, The execution device is a loss estimating process for calculating an estimated value of a pumping loss of the internal combustion engine so that the estimated value is larger as an intake pressure, which is the pressure of air in a portion of the intake passage downstream of the throttle valve, is lower, as an engine speed of the internal combustion engine is higher, and as a supercharging pressure is higher; a required value setting process for setting a required boost pressure, which is a required value of the boost pressure, to a larger value as a required value of an output torque of the internal combustion engine increases; an opening adjustment process for adjusting an opening of the wastegate valve so that the opening of the wastegate valve becomes smaller as the required boost pressure increases; and a leveling process for calculating a required boost pressure smoothed value, which is a leveled value of the required boost pressure. The boost pressure used in the loss estimation process is the smoothed value of the required boost pressure. Internal combustion engine control device.

2. An internal combustion engine control device that is applied to an internal combustion engine that includes a cylinder, a supercharger, an intake passage through which air to be introduced into the cylinder flows, a throttle valve installed in the intake passage, and an exhaust passage through which exhaust gas discharged from inside the cylinder flows, the turbocharger is provided in the exhaust passage and has a turbine wheel that rotates due to the flow of exhaust gas flowing through the exhaust passage, a compressor wheel that is provided in a portion of the intake passage upstream of the throttle valve and rotates in synchronization with the turbine wheel, and a wastegate valve that adjusts the flow rate of exhaust gas that bypasses the turbine wheel out of the exhaust gas flowing through the exhaust passage, The internal combustion engine control device includes an execution device, the execution device executes a loss estimation process for calculating an estimated value of a pumping loss of the internal combustion engine such that the estimated value is larger as an intake pressure, which is the pressure of air in a portion of the intake passage downstream of the throttle valve, is lower, the engine speed of the internal combustion engine is higher, and the estimated value is larger as a supercharging pressure is higher, The intake pressure used in the loss estimation process is a value normalized by the atmospheric pressure. Internal combustion engine control device.

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