JP2017025755A - Controller of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controller of an internal combustion engine capable of securing excellent travel responsiveness even in a case of performing feedback control for supercharging pressure under an environment having low atmospheric pressure.SOLUTION: A controller of an internal combustion engine with a supercharger includes a control unit configured to perform feedback control for supercharging pressure so that an actual supercharging pressure is a target supercharging pressure, wherein PID control is used as the feedback control. The control unit corrects a proportional gain Kp of a P term in the PID control on the basis of atmospheric pressure P. The proportional gain Kp is corrected so as to become larger as the atmospheric pressure P lowers.SELECTED DRAWING: Figure 4

Description

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

  Conventionally, in a control device for an internal combustion engine that feedback-controls a supercharging pressure adjustment unit so that a supercharging pressure becomes a target supercharging pressure, for example, when traveling in a low atmospheric pressure environment such as a high altitude, the lower the atmospheric pressure, What correct | amends so that target supercharging pressure may be reduced is known (for example, refer patent document 1). According to the control device for an internal combustion engine, it is possible to prevent over-rotation of the supercharger when the atmospheric pressure is low.

JP-A-2-163419

  However, in the above-described conventional control device for an internal combustion engine, no consideration has been given to running responsiveness when running in an environment where the atmospheric pressure is low. That is, when the atmospheric pressure is low, for example, when feedback control of the supercharging pressure is performed as in the lowland where the sea level is low, the followability of the actual supercharging pressure with respect to the target supercharging pressure may be deteriorated. As a result, in the conventional control device for an internal combustion engine, there is a possibility that the traveling responsiveness may decrease when the vehicle travels in an environment where the atmospheric pressure is low.

  The present invention has been made in view of such circumstances, and provides a control device for an internal combustion engine that can ensure good running response even when feedback control of supercharging pressure is performed in an environment where atmospheric pressure is low. The purpose is to do.

  The present invention is a control device for an internal combustion engine with a supercharger, comprising a control unit that performs feedback control of supercharging pressure so that the actual supercharging pressure becomes a target supercharging pressure, and PID is used as the feedback control. Control is used, and the control unit corrects the proportional gain of the proportional term in the PID control based on atmospheric pressure.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where feedback control of supercharging pressure is performed in the environment where atmospheric pressure is low, the control apparatus of the internal combustion engine which can ensure favorable driving | running response can be provided.

FIG. 1 is a schematic configuration diagram showing a main part of a vehicle equipped with an internal combustion engine control apparatus according to an embodiment of the present invention. FIG. 2 is a graph showing a change in actual supercharging pressure when the target supercharging pressure is changed. FIG. 3 is a flowchart showing a flow of processing of atmospheric pressure correction control executed in the control device for an internal combustion engine according to the embodiment of the present invention. FIG. 4 is a flowchart showing the flow of the P term correction process executed in step S2 of FIG. FIG. 5 is an example of a correction table for the P term corresponding to the atmospheric pressure. FIG. 6 is a flowchart showing the flow of the boost pressure abnormality determination correction process executed in step S3 of FIG. FIG. 7 is an example of a supercharging pressure abnormality determination value table according to atmospheric pressure.

  Embodiments of the present invention will be described below with reference to FIGS. As shown in FIG. 1, a vehicle 1 equipped with a control device for an internal combustion engine according to this embodiment includes an engine 2 and an ECU 10.

  The engine 2 is an internal combustion engine with a supercharger, and is a so-called direct injection gasoline engine that directly injects fuel pumped from a fuel tank (not shown) by a fuel pump into the combustion chamber 2a. The engine 2 is not limited to the direct injection type, but may be a port injection type, or may be not only a gasoline engine but also an engine of a type such as a diesel engine.

  An intake pipe 3 is connected to the engine 2, and an intake passage communicating with an intake port (not shown) is formed in the intake pipe 3. The intake passage is provided with an air cleaner 31 for purifying the intake air, a compressor 32 for compressing the air, an intercooler 33 for cooling the compressed air, and a throttle valve 34 for adjusting the flow rate of the air.

  An exhaust pipe 4 is connected to the engine 2, and an exhaust passage communicating with an exhaust port (not shown) is formed in the exhaust pipe 4. The exhaust passage is provided with an exhaust turbine 42 driven by an exhaust flow, a catalyst (not shown), a muffler, and the like.

  The exhaust turbine 42 is connected to the compressor 32. The power of the exhaust turbine 42 driven by the exhaust flow is used as power for the compressor 32 to compress air. The compressor 32 and the exhaust turbine 42 constitute the supercharger 5.

  The supercharger 5 has a wastegate valve 51 that can adjust the exhaust flow to the exhaust turbine 42. The wastegate valve 51 can control the supercharging pressure that is the pressure of the intake air obtained by supercharging the supercharger 5 by adjusting the exhaust flow to the exhaust turbine 42. The wastegate valve 51 is configured by, for example, an electromagnetic valve and is controlled to be opened and closed by the ECU 10.

  The ECU 10 includes, for example, a microcomputer including a CPU, a RAM, a ROM, an input / output interface, and the like. The CPU uses a temporary storage function of the RAM and performs signal processing according to a program stored in advance in the ROM. It is like that. Various control constants and various maps are stored in advance in the ROM.

  Various sensors such as an accelerator sensor 101, an atmospheric pressure sensor 102, an intake air temperature sensor 103, an air flow meter 104, and a MAP sensor 105 are connected to the input side of the ECU 10.

  The accelerator sensor 101 detects the amount of depression of an accelerator pedal (not shown) by the driver as the accelerator opening. The atmospheric pressure sensor 102 detects the atmospheric pressure P [hPa]. The intake air temperature sensor 103 detects the intake air temperature, which is the temperature of the air taken into the engine 2.

  The air flow meter 104 detects an intake air amount that is an amount of air taken into the engine 2. The MAP sensor 105 detects the supercharging pressure of the air supercharged by the supercharger 5.

  Various devices such as a throttle valve 34, a waste gate valve 51, an injector (not shown) and a spark plug (not shown) provided in the engine 2 are connected to the output side of the ECU 10.

  The ECU 10 determines the supercharging pressure of the air supercharged by the supercharger 5 when a supercharging pressure control start condition such as the opening of the throttle valve 34, that is, the throttle opening exceeds a predetermined opening is satisfied. Has a function as the control unit 11 that performs supercharging pressure control for controlling the wastegate valve 51 and the throttle valve 34 so that the target supercharging pressure becomes the target supercharging pressure. The target boost pressure is set according to the engine speed, for example.

  As the supercharging pressure control, feedback control for converging the actual supercharging pressure to the target supercharging pressure is used. Specifically, the proportional term (P term), the integral term (I term), and the differential term (D term). PID control is used in combination.

  Here, for example, in an environment where the atmospheric pressure is low such as a high altitude, the followability of the actual supercharging pressure with respect to the target supercharging pressure is reduced as compared with the low altitude. Therefore, in the present embodiment, in order to ensure followability of the actual supercharging pressure with respect to the target supercharging pressure in an environment where the atmospheric pressure is low, correction according to the atmospheric pressure is performed in the PID control described above. Yes.

  Specifically, the ECU 10 performs a P term correction process for correcting the proportional gain Kp of the P term in the PID control based on the atmospheric pressure P [hPa] detected by the atmospheric pressure sensor 102. The proportional gain Kp is corrected to a larger value as the atmospheric pressure decreases. Thereby, the responsiveness of actual supercharging pressure increases as the atmospheric pressure decreases.

  Further, the ECU 10 has a function as an abnormality determination unit 12 that determines abnormality of the supercharging pressure based on whether or not the actual supercharging pressure is within a normal range. The ECU 10 determines whether or not the actual supercharging pressure is within the normal range based on the overshoot amount and undershoot amount of the actual supercharging pressure with respect to the target supercharging pressure.

  Specifically, the ECU 10 determines whether or not the actual boost pressure is in the normal region by determining whether or not the difference D between the actual boost pressure and the target boost pressure is equal to or less than a predetermined abnormality determination value Dth. It is determined whether it is within the range. For example, the ECU 10 determines that the actual supercharging pressure is within the normal range when the difference D is equal to or less than the abnormality determination value Dth.

  Here, in the present embodiment, the ECU 10 performs PID control of the supercharging pressure using a proportional gain having a larger value as the atmospheric pressure decreases as described above. For this reason, as shown in FIG. 2, the actual supercharging pressure overshoot amount α with respect to the target supercharging pressure is increased because the response of the actual supercharging pressure is enhanced as compared with the case of the lowland indicated by the solid line in the figure. In addition, the undershoot amount β increases as shown by the alternate long and short dash line in the figure. The example shown in FIG. 2 shows a case where the target supercharging pressure is changed from Pa to Pb.

  On the other hand, in the case of the lowland indicated by the solid line in the figure, the actual overshoot amount and undershoot amount of the supercharging pressure are smaller than those in the highland (with correction) indicated by the alternate long and short dash line in the figure.

  Therefore, when the ECU 10 performs the abnormality determination of the supercharging pressure as described above by using the abnormality determination value Dth set with reference to the range of the normal region similar to the lowland in the environment where the atmospheric pressure is low, that is, the lowland. There is a possibility that it is erroneously determined to be abnormal although it is not actually abnormal.

  Therefore, in the present embodiment, in order to prevent erroneous determination in the abnormality determination of the supercharging pressure, the normal region in the abnormality determination of the supercharging pressure based on the atmospheric pressure P [hPa] detected by the atmospheric pressure sensor 102. An abnormality determination correction process for correcting the range, that is, the abnormality determination value Dth is performed. The range of the normal region in the abnormality determination of the supercharging pressure is expanded as the atmospheric pressure decreases.

  Next, the P term correction process and the boost pressure abnormality determination correction process executed by the ECU 10 will be described with reference to FIGS. First, atmospheric pressure correction control including P-term correction processing and boost pressure abnormality determination correction processing will be described.

  First, the atmospheric pressure correction control including the P-term correction process and the boost pressure abnormality determination correction process will be described with reference to FIG. The atmospheric pressure correction control is a control for determining whether or not to perform correction processing in the supercharging pressure control and the supercharging pressure abnormality determination, and until the engine 2 is turned off, that is, until the engine 2 is stopped. To be executed.

  As shown in FIG. 3, the ECU 10 determines whether or not the target boost pressure has been changed (step S1). In step S1, when it is determined that the target boost pressure has not been changed, the ECU 10 performs the determination in step S1 again.

  In step S1, when it is determined that the target boost pressure has been changed, the ECU 10 executes a P-term correction process for boost pressure control (step S2). Next, the ECU 10 performs a boost pressure abnormality determination correction process (step S3).

  In the present embodiment, the P-term correction process in step S2 and the abnormality determination correction process in step S3 are performed. However, the present invention is not limited to this. For example, only one of the correction processes may be performed.

  Next, the ECU 10 determines whether or not the engine 2 is turned off (step S4). The ECU 10 can determine whether or not the engine 2 is turned off, for example, by determining whether or not an ignition switch (not shown) is turned off.

  In step S4, when it is determined that the engine 2 is not turned off, the ECU 10 repeats the processing after step S1 again. In step S4, when the ECU 10 determines that the engine 2 is turned off, the atmospheric pressure correction control ends.

  Next, the P term correction process executed in step S2 of the atmospheric pressure correction control shown in FIG. 3 will be described with reference to FIG.

  As shown in FIG. 4, the ECU 10 substitutes an initial value “1” for a variable n for deriving an atmospheric pressure threshold value Pth1 [n] described later (step S21).

  Next, the ECU 10 detects the atmospheric pressure P via the atmospheric pressure sensor 102 (step S22). Thereafter, the ECU 10 determines whether or not the atmospheric pressure P detected in step S22 is smaller than the atmospheric pressure threshold value Pth1 [n] (step S23).

  The ECU 10 determines the atmospheric pressure threshold value Pth1 [n] by referring to the correction table shown in FIG. 5 according to the value of the variable n. For example, when n = 1, 700 [hPa] is determined as the atmospheric pressure threshold Pth1 [n]. The atmospheric pressure threshold value Pth1 [n] is defined so as to increase as the variable n increases.

  In step S23, if the ECU 10 determines that the atmospheric pressure P detected in step S22 is not smaller than the atmospheric pressure threshold value Pth1 [n], it substitutes “n + 1” for the variable n (step S24) and again. The process of step S23 is performed.

  Therefore, the ECU 10 increases the variable n until the atmospheric pressure P becomes smaller than the atmospheric pressure threshold value Pth1 [n] in step S23, and refers to the atmospheric pressure threshold value with reference to the correction table shown in FIG. Pth1 [n] is increased.

  In step S23, when the ECU 10 determines that the atmospheric pressure P detected in step S22 is smaller than the atmospheric pressure threshold value Pth1 [n], the ECU 10 sets Kp [n] as the proportional gain Kp of the P term in the supercharging pressure control. Substitution is made (step S25), and the P-term correction process is terminated.

  Specifically, the ECU 10 determines Kp [n] by referring to the correction table shown in FIG. 5 according to the value of the variable n. For example, when n = 3, “c” is determined as Kp [n]. Kp [n] is defined to be larger as the atmospheric pressure threshold Pth1 [n] is smaller.

  The correction table shown in FIG. 5 is obtained experimentally in advance and is stored in the ROM of the ECU 10. Note that each atmospheric pressure threshold value Pth1 [n] in the correction table shown in FIG. 5 is an example, and may not be defined every 50 [hPa].

  Next, an intake pressure abnormality determination correction process executed in step S3 of the atmospheric pressure correction control shown in FIG. 3 will be described with reference to FIG.

  As shown in FIG. 6, the ECU 10 substitutes an initial value “1” into a variable n for deriving an atmospheric pressure threshold value Pth2 [n] described later (step S31).

  Next, the ECU 10 detects the atmospheric pressure P via the atmospheric pressure sensor 102 (step S32). Thereafter, the ECU 10 determines whether or not the atmospheric pressure P detected in step S32 is smaller than the atmospheric pressure threshold value Pth2 [n] (step S33).

  The ECU 10 determines the atmospheric pressure threshold value Pth2 [n] by referring to the abnormality determination value table shown in FIG. 7 according to the value of the variable n. For example, when n = 1, 700 [hPa] is determined as the atmospheric pressure threshold value Pth2 [n]. The atmospheric pressure threshold value Pth2 [n] is defined so as to increase as the variable n increases.

  In step S33, if the ECU 10 determines that the atmospheric pressure P detected in step S32 is not smaller than the atmospheric pressure threshold Pth2 [n], it substitutes “n + 1” for the variable n (step S34), and again. The process of step S33 is performed.

  Therefore, the ECU 10 increases the variable n until the atmospheric pressure P becomes smaller than the atmospheric pressure threshold value Pth2 [n] in step S33, and each time the ECU 10 refers to the abnormality determination value table shown in FIG. The threshold value Pth2 [n] is increased.

  In step S33, when the ECU 10 determines that the atmospheric pressure P detected in step S32 is smaller than the atmospheric pressure threshold value Pth2 [n], the ECU 10 substitutes Dth [n] as the boost pressure abnormality determination value Dth. (Step S35), the intake pressure abnormality determination correction processing is terminated.

  Specifically, the ECU 10 determines Dth [n] by referring to the abnormality determination value table shown in FIG. 7 according to the value of the variable n. For example, when n = 3, “C” is determined as Dth [n]. Dth [n] is defined to be larger as the atmospheric pressure threshold Pth2 [n] is smaller.

  The abnormality determination value table shown in FIG. 7 is obtained experimentally in advance and is stored in the ROM of the ECU 10. In addition, each atmospheric | air pressure threshold value Pth2 [n] in the abnormality determination value table shown in FIG. 7 is an example, and does not need to be prescribed | regulated every 50 [hPa].

  As described above, the control device for an internal combustion engine according to the present embodiment corrects the proportional gain Kp of the P term in the supercharging pressure control (PID control) based on the atmospheric pressure P. Supercharging pressure feedback control can be performed using the proportional gain Kp.

  Thereby, the control device for the internal combustion engine according to the present embodiment improves the follow-up performance of the actual supercharging pressure with respect to the target supercharging pressure as compared with the case where the proportional gain Kp is not changed according to the atmospheric pressure. Can do. Therefore, the control device for an internal combustion engine according to the present embodiment can ensure a good running response even when the feedback control of the supercharging pressure is performed in an environment where the atmospheric pressure is low.

  The control device for an internal combustion engine according to the present embodiment corrects the proportional gain Kp to a larger value as the atmospheric pressure P decreases, so that the actual control is more effective than when the atmospheric pressure P is high, such as in a lowland. The responsiveness of the supercharging pressure can be improved.

  When the proportional gain Kp is corrected as described above, the overshoot amount and undershoot amount of the actual supercharging pressure increase. However, the control apparatus for an internal combustion engine according to the present embodiment corrects the abnormality determination value Dth based on the atmospheric pressure P in the determination of the abnormality of the supercharging pressure. Therefore, the overshoot of the actual supercharging pressure as described above. It is possible to prevent erroneous determination that the supercharging pressure is abnormal due to an increase in the amount and the undershoot amount.

  The control apparatus for an internal combustion engine according to the present embodiment corrects the abnormality determination value Dth to a larger value as the atmospheric pressure P decreases. The range of the normal area in the abnormality determination of the supply pressure can be expanded.

  In the present embodiment, the atmospheric pressure P [hPa] is detected by the atmospheric pressure sensor 102. However, the present invention is not limited to this. For example, the ECU 10 calculates based on the intake air amount detected by the air flow meter 104. May be.

  Although the embodiments of the present invention have been disclosed as described above, it is obvious that those skilled in the art can make changes without departing from the scope of the present invention. All such modifications and equivalents are intended to be included in the following claims.

1 vehicle 2 engine (internal combustion engine)
5 Supercharger 10 ECU
DESCRIPTION OF SYMBOLS 11 Control part 12 Abnormality determination part 34 Throttle valve 51 Wastegate valve 102 Atmospheric pressure sensor 105 MAP sensor

Claims (4)

A control device for an internal combustion engine with a supercharger,
A control unit that performs feedback control of the supercharging pressure so that the actual supercharging pressure becomes the target supercharging pressure,
PID control is used as the feedback control,
The control unit for an internal combustion engine, wherein the control unit corrects a proportional gain of a proportional term in the PID control based on atmospheric pressure.   2. The control device for an internal combustion engine according to claim 1, wherein the control unit corrects the proportional gain to a larger value as the atmospheric pressure decreases. Further comprising an abnormality determination unit for determining abnormality of the supercharging pressure based on whether or not the actual supercharging pressure is within a normal range;
The control apparatus for an internal combustion engine according to claim 1, wherein the abnormality determination unit corrects the range of the normal region based on atmospheric pressure. The control apparatus for an internal combustion engine according to claim 3, wherein the abnormality determination unit expands the range of the normal region as the atmospheric pressure decreases.

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