JP2016118139A - Control device of internal combustion engine - Google Patents

Abstract

The present invention relates to a control device for an internal combustion engine, and in an internal combustion engine equipped with an electric supercharger, it is possible to assist acceleration so as to obtain a sustained acceleration while considering an increase in power consumption. When an acceleration of a vehicle accompanied by an assist by the electric motor 24b of the electric supercharger 24 is requested, an overload by the electric motor 24b is detected when a delay time td from the start of the acceleration of the vehicle elapses. To the electric motor 24b after the start of supercharging so that the rotational speed of the electric compressor 24a increases according to a quadratic function that is a quadratic function with respect to time and a positive quadratic coefficient. Control energization. [Selection] Figure 4

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for an internal combustion engine suitable as a device for controlling an internal combustion engine including an electric supercharger.

  Conventionally, for example, Patent Document 1 discloses a vehicle driving force control device including an internal combustion engine and an electric motor as power sources. This conventional control device sets the target acceleration of the vehicle based on the situation around the vehicle and the operation state of the accelerator pedal when the vehicle is accelerated. The greater the set target acceleration, the higher the driving force of the vehicle. The vehicle driving force is increased by controlling at least one of engine output, electric motor output, vehicle transmission gear ratio, vehicle lockup clutch engagement / release, and the like. . The target acceleration is set using Weber-Hefner's law so that the relationship between the amount of change in the pedal effort of the accelerator pedal and the actual acceleration of the vehicle conforms to human perceptual characteristics. Specifically, the target acceleration is set to increase exponentially as the pedal effort increases.

JP 2009-057874 A JP 2008-267368 A JP 2011-113032 A JP2013-204534A

  The above-mentioned Patent Document 1 discloses that the target acceleration, which is an acceleration that is a target to be reached when the vehicle is accelerated, is set to a value according to the pedal effort of the accelerator pedal using Weber-Hefner's law. . However, Patent Document 1 does not disclose what kind of shape the trajectory of the temporal change in acceleration during the acceleration period is.

  By the way, according to the internal combustion engine provided with the electric supercharger, it is possible to assist the acceleration of the vehicle by the internal combustion engine by adjusting the supercharging pressure by controlling the energization of the electric motor. Electric power is required to operate the electric motor. For this reason, when assisting the acceleration of a vehicle by electric assist by the electric motor, if the maximum electric power that can be supplied to the electric motor is always given without special consideration, the acceleration response can be sufficiently increased even if the acceleration response can be sufficiently increased. Increasing the amount of power can be a problem. Therefore, when increasing the acceleration response using the electric assist, it can be said that it is desirable to provide a sufficient acceleration feeling to the driver of the vehicle while taking into account the increase in power consumption. Here, it is generally known that the feeling of acceleration felt by the driver is influenced not only by the acceleration response but also by the jerk of the vehicle, and the driver can discriminate between the acceleration and deceleration depending on the magnitude of the jerk. Therefore, according to the acceleration characteristic in which the jerk increases with time according to a linear function, it is considered that acceleration with a high degree of sustaining that makes the driver feel that acceleration has been sustained for a long time is obtained.

  The present invention has been made to solve the above-described problems. In an internal combustion engine equipped with an electric supercharger, acceleration assistance is provided so that a sustained acceleration can be obtained while considering an increase in power consumption. It is an object of the present invention to provide a control device for an internal combustion engine that can perform the above-described operation.

  An internal combustion engine control apparatus according to the present invention controls an internal combustion engine including an electric supercharger having a compressor for supercharging intake air and an electric motor capable of driving the compressor, and includes an electric motor control means. ing. The electric motor control means controls energization of the electric motor. More specifically, the motor control means is configured such that when a vehicle equipped with the internal combustion engine is requested to accelerate with the assistance of the electric supercharger, a delay time from the start of acceleration of the vehicle elapses. The supercharging by the electric motor is started, and the supercharging is started so that the rotational speed of the compressor increases according to a quadratic function that is a quadratic function with respect to time and the quadratic coefficient is positive. The energization to the subsequent motor is controlled.

  The delay time is preferably shorter as the accelerator opening of the accelerator pedal is larger when acceleration of the vehicle is required.

  When the accelerator opening of the accelerator pedal is changed during the lapse of the delay time, the electric motor control means updates the delay time so as to become shorter as the changed accelerator opening becomes larger. Also good.

  When the acceleration of the vehicle is requested, the motor control means may correct the secondary coefficient used for controlling energization of the motor to a larger value as the accelerator opening of the accelerator pedal is larger. preferable.

  When the accelerator opening of the accelerator pedal is changed during acceleration of the vehicle, the motor control means is configured to use the second order coefficient used for controlling energization of the motor as the changed accelerator opening is larger. May be a larger value.

  The motor control means energizes the motor so that the higher the gear ratio of the vehicle used when acceleration of the vehicle is required, the higher the rotational speed of the compressor reached during acceleration. It may be one that controls.

  The delay time is preferably a period until acceleration finishes increasing according to a quadratic function in acceleration of the vehicle without assistance from the electric motor.

  As described above, according to the acceleration characteristic in which the jerk increases with time according to a linear function, it is considered that acceleration with a high degree of sustainability that allows the driver to feel that the acceleration has continued for a long time is obtained. It is done. And when this acceleration characteristic is obtained, the time change rate of jerk shows a fixed value. There is a period in which the acceleration can be considered to increase according to a quadratic function at the initial stage of acceleration of the vehicle without the electric assist, and after this period, there is a period in which the acceleration can be considered to increase according to the linear function. According to the present invention, by providing a delay time at the initial stage of acceleration, the time-varying rate of jerk can be set to the initial stage of acceleration without using the electric power of the motor by utilizing the characteristics of the initial stage of acceleration of the vehicle without electric assist. In FIG. 4, it can be made constant over time. In addition, according to the present invention, in the supercharging by the electric motor that starts when the delay time elapses, the rotation of the compressor of the electric supercharger according to a quadratic function in which the second-order coefficient is positive and time is an independent variable. Energization is controlled to increase the speed. As a result, the acceleration during the energization control can be increased in a quadratic function. As a result, the rate of change in jerk over time can be made constant over time during the period in which acceleration rises during acceleration. As described above, according to the present invention, acceleration assistance can be performed so as to obtain sustained acceleration while considering increase in power consumption.

It is a figure for demonstrating the system configuration | structure of the internal combustion engine in Embodiment 1 of this invention. It is a time chart showing the reference example of the electric assist referred for contrast with the characteristic electric assist control in Embodiment 1 of this invention. It is a figure for demonstrating the acceleration characteristic in which acceleration with a high feeling of sustain is obtained. It is a time chart for demonstrating the control method of the electric motor for making time change rate R of jerk (DELTA) G approach constant. It is a figure which shows the relationship between the acceleration G and a supercharging pressure. It is a figure which shows the relationship between a supercharging pressure and the rotational speed of an electric supercharger (electric compressor). It is a figure which shows the relationship between the rotational speed of an electric supercharger, and the applied voltage of an electric motor. It is a time chart for demonstrating the difference according to the accelerator opening about the locus | trajectory of the time change of the acceleration G for the base acceleration which does not accompany electric assistance. It is a time chart for demonstrating the method of controlling the locus | trajectory of the time change of the acceleration G using an electric assist so that it may become a locus | trajectory according to an accelerator opening. It is a time chart showing an example of the difference of the locus of the time change of acceleration G by the difference of a shift position. It is a time chart for demonstrating control of the locus | trajectory of the time change of the acceleration G performed when stepping on an accelerator pedal is performed during acceleration. It is a flowchart which shows the flow of the electric assist control at the time of the acceleration in Embodiment 1 of this invention. It is a figure showing the characteristic of the map which predetermined the relationship between accelerator opening and delay time td.

Embodiment 1 FIG.
[System configuration of the first embodiment]
FIG. 1 is a diagram for explaining a system configuration of an internal combustion engine 10 according to Embodiment 1 of the present invention. An internal combustion engine 10 shown in FIG. 1 includes an internal combustion engine body 12. The internal combustion engine 10 is a spark ignition engine (a gasoline engine as an example) and is mounted on a vehicle and used as a power source. An intake passage 14 and an exhaust passage 16 communicate with each cylinder of the internal combustion engine body 12. Note that the present invention is not limited to a spark ignition engine, and can be similarly applied to a compression ignition engine such as a diesel engine.

  An air cleaner 18 is provided in the vicinity of the inlet of the main intake passage 14 a of the intake passage 14. The air cleaner 18 is provided with an air flow meter 20 that outputs a signal corresponding to the flow rate of air flowing through the main intake passage 14a. A compressor 22a (hereinafter referred to as “turbo compressor 22a”) of the turbocharger 22 is disposed in the main intake passage 14a downstream of the air cleaner 18 in order to supercharge intake air. The turbocharger 22 includes a turbine 22 b that operates by exhaust energy of exhaust gas in the exhaust passage 16. The turbo compressor 22a is integrally connected to the turbine 22b via a connecting shaft, and is rotationally driven by the exhaust energy of the exhaust gas input to the turbine 22b.

  The intake passage 14 includes an intake bypass passage 14b. The intake bypass passage 14b bypasses the main intake passage 14a downstream of the air cleaner 18 and upstream of the turbo compressor 22a. A compressor 24a (hereinafter referred to as “electric compressor 24a”) of the electric supercharger 24 is disposed in the intake bypass passage 14b. The electric compressor 24a is driven by the electric motor 24b. Electric power is supplied to the electric motor 24b from a battery (not shown). An intake bypass valve 26 that opens and closes the main intake passage 14a is disposed at a portion of the main intake passage 14a located between the upstream end portion and the downstream end portion of the intake bypass passage 14b.

  An intercooler 28 for cooling the intake air compressed by the turbo compressor 22a or both the turbo compressor 22a and the electric compressor 24a is disposed in the main intake passage 14a on the downstream side of the turbo compressor 22a. An electronically controlled throttle valve 30 that opens and closes the main intake passage 14a is disposed in the main intake passage 14a downstream of the intercooler 28. The main intake passage 14a on the downstream side of the throttle valve 30 is configured as an intake manifold 14c, and the intake air is distributed to each cylinder via the intake manifold 14c. An intake pressure sensor 32 that detects an intake pressure (more specifically, an intake manifold pressure) is attached to the intake manifold 14c.

  Exhaust gas from each cylinder is collected by the exhaust manifold 16a of the exhaust passage 16 and discharged downstream. The exhaust passage 16 includes an exhaust bypass passage 16b that bypasses the turbine 22b. In the exhaust bypass passage 16b, an electronically controlled waste gate valve (WGV) 34 is disposed as a bypass valve for opening and closing the exhaust bypass passage 16b. By changing the opening degree of the WGV 34, it is possible to adjust the driving force of the turbo compressor 22a by adjusting the flow rate of the exhaust gas passing through the turbine 22b.

  Furthermore, the system according to the present embodiment includes an ECU (Electronic Control Unit) 40 as a control device for controlling the internal combustion engine 10 and a drive circuit (not shown) for driving the following various actuators. The ECU 40 includes at least an input / output interface, a memory, and an arithmetic processing unit (CPU), and controls the entire system of the internal combustion engine 10. The input / output interface is provided to take in sensor signals from various sensors attached to the internal combustion engine 10 or a vehicle on which the internal combustion engine 10 is mounted, and to output operation signals to various actuators included in the internal combustion engine 10. The memory stores various control programs and maps for controlling the internal combustion engine 10. The CPU reads out and executes a control program or the like from the memory, and generates operation signals for various actuators based on the acquired sensor signals.

  In addition to the air flow meter 20 and the intake pressure sensor 32 described above, the ECU 40 acquires signals for the engine operating state such as the crank angle sensor 42 for acquiring the rotational position of the crankshaft and the engine rotational speed. Various sensors are included. The above sensors are combined with an accelerator position sensor 44 for detecting an accelerator pedal depression amount (accelerator opening) of a vehicle on which the internal combustion engine 10 is mounted, a vehicle speed sensor 46 for detecting a vehicle speed, and the internal combustion engine 10. Also included is a shift position sensor 48 for detecting the shift position of an operating mechanism (not shown) for switching the transmission ratio of a transmission (not shown).

  In addition to the electric motor 24b, the intake bypass valve 26, the throttle valve 30 and the WGV 34, the actuator from which the ECU 40 outputs an operation signal includes a fuel injection valve 50 for supplying fuel into the combustion chamber of each cylinder, and each combustion chamber. Various actuators for controlling engine operation such as an ignition device 52 for igniting the air-fuel mixture are included.

[Control of Embodiment 1]
(Available supercharging modes)
According to the electric supercharger 24, the intake air can be supercharged by driving the electric compressor 24a by the electric motor 24b. By providing the above configuration, the internal combustion engine 10 is a single supercharging mode that is a supercharging mode that uses only the turbocharger 22, and a twin that is a supercharging mode that uses the electric compressor 24 a together with the turbocharger 22. The supercharging mode can be selected alternatively. In the single supercharging mode, energization to the electric motor 24b is stopped, and the intake bypass valve 26 is fully opened. As a result, the intake air supercharged by the turbo compressor 22a using exhaust energy is supplied to the combustion chambers of the respective cylinders while avoiding the electric compressor 24a becoming intake resistance. On the other hand, in the twin supercharging mode, the electric motor 24b is energized with the intake bypass valve 26 closed. As a result, the intake air introduced into the intake passage 14 is sequentially supercharged by the electric compressor 24a and the turbo compressor 22a and then supplied to the combustion chamber of each cylinder. Thereby, supercharging by the turbocharger 22 can be assisted using the electric supercharger 24. Hereinafter, the supercharging assist using the electric supercharger 24 is simply referred to as “electric assist”.

(Reference example of electric assist to maximize acceleration response)
FIG. 2 is a time chart showing a reference example of the electric assist referred for comparison with the characteristic electric assist control in the first embodiment of the present invention. In addition, each example of the acceleration operation shown in FIG. 2 is when the vehicle is accelerated using the supercharging from the natural intake state.

  A waveform indicated by a broken line in FIG. 2 indicates a waveform of acceleration G at the time of acceleration performed using the supercharging by the turbocharger 22 without using electric assist. Such acceleration is realized by fully opening the throttle valve 30 and controlling the opening of the WGV 34 to the minimum opening when an acceleration request is issued. A time point t0 in FIG. 2 is an acceleration request time point. The linear increase of the acceleration G in the period from the time point t0 to the time point t1 is realized as a result of the engine torque increasing rapidly as the throttle valve 30 is fully opened quickly. The trajectory of the time change of the acceleration G in the period from the time point t1 to the time point t2 depends on the responsiveness of supercharging by the turbocharger 22. More specifically, it takes time for the rotational speed of the turbine 22b (that is, the rotational speed of the turbo compressor 22a) to reach a rotational speed at which the turbocharger 22 can perform sufficient supercharging during acceleration. For this reason, the increase degree of the acceleration G in the period after the time point t1 is lower than the increase degree of the acceleration G in the period before the time point t1.

  On the other hand, the waveform shown by the solid line in FIG. 2 shows the waveform of the acceleration G in the acceleration performed using the maximum supercharging by the turbocharger 22 with the maximum electric assist available. . In this acceleration, an acceleration with the maximum electric assistance can be realized by applying an applied voltage to the electric motor 24b so that the electric motor 24b can exhibit the maximum output. As a result, it is possible to linearly raise the acceleration G after time t1 at a higher rate than in the case without electric assist.

(Necessity to control time-varying trajectory of acceleration G during acceleration)
In the present embodiment, electric assist is used to assist supercharging by the turbocharger 22 during vehicle acceleration. According to the acceleration assist by the electric assist, the acceleration response of the internal combustion engine 10 can be improved. However, electric power is required to operate the electric motor 24b for assisting acceleration. More specifically, in order to obtain this electric power, it is necessary to generate power using an alternator (not shown) provided in the internal combustion engine 10 or the like. The alternator generates power using the power of the internal combustion engine 10. For this reason, an increase in power consumption of the electric motor 24b leads to a deterioration in fuel consumption of the internal combustion engine 10. Therefore, when assisting the acceleration of the vehicle by the electric assist, if the maximum electric power that can be supplied to the electric motor 24b is always given as shown by the solid line in FIG. 2, the following situation is concerned. . That is, according to the acceleration with the maximum electric assist, the time required to reach the same acceleration G is shortened as compared with the acceleration without the electric assist, that is, the acceleration response can be sufficiently improved. On the other hand, even if the acceleration response can be sufficiently increased, the amount of power consumption increases and the fuel consumption may deteriorate. In FIG. 2, the acceleration G is constant during a period from time t3 to time t2 in acceleration with maximum electric assist. For this reason, this acceleration is weak in sustainability (elongation) compared to acceleration without electric assist.

  As described above, acceleration with maximum electric assist can maximize acceleration responsiveness, but consumes a large amount of power, and the feeling given to the driver of the vehicle is low. It will be a thing. Here, if the driver can be given a sustained feeling of acceleration even if the electric power given to the electric motor 24b is small compared with the acceleration with the maximum electric assist, the driver can be considered while considering the increase in power consumption. On the other hand, it is thought that sufficient acceleration can be brought about.

(Control of trajectory of characteristic acceleration G over time in Embodiment 1)
Therefore, in the present embodiment, in order to realize acceleration with a feeling of sustainability (a feeling of growth) while taking into account the increase in power consumption, the trajectory of the time change of acceleration G during acceleration using electric assist will be described below. It was decided to control it.

  FIG. 3 is a diagram for explaining acceleration characteristics that can achieve acceleration with a high degree of sustainability. The trajectory of the time change of the acceleration G shown in FIG. 3 is obtained when the acceleration G increases according to a quadratic function in which the secondary coefficient is positive and time is an independent variable. If the locus of acceleration G is a quadratic function with time as an independent variable, the locus of jerk ΔG, which is the time derivative of acceleration G, increases with time according to the linear function as shown in FIG. It becomes. In general, it is known that the acceleration feeling felt by the driver is influenced by the jerk ΔG, and the driver can discriminate whether the acceleration is slow or not based on the magnitude of the jerk ΔG. Therefore, as shown in FIG. 3, according to the acceleration characteristic in which the jerk ΔG increases with time according to a linear function, acceleration with a high degree of sustainability that makes the driver feel that the acceleration has continued for a long time is achieved. It is thought that it is obtained. According to the acceleration characteristic shown in FIG. 3, the time change rate R of the jerk ΔG (that is, the slope of the straight line indicating the change in the jerk ΔG with respect to the change in time) is a constant value. In this embodiment, since “acceleration” of the vehicle is handled, the time change rate R of the jerk ΔG is a positive value.

  In other words, if the time change rate R of the jerk ΔG during the period in which the acceleration G rises can be made close to a constant value, a locus of acceleration G close to a locus according to a quadratic function as shown in FIG. 3 is obtained. As a result, it can be said that acceleration with a high degree of sustainability can be obtained. Then, if the time change rate R during the period in which the acceleration G rises can be made closer to a constant value with a larger value, it can be said that acceleration with a sense of sustain can be obtained while improving the acceleration response.

  FIG. 4 is a time chart for explaining a control method of the electric motor 24b for making the time change rate R of the jerk ΔG close to a constant value. FIG. 5 shows the relationship between the acceleration G and the supercharging pressure, FIG. 6 shows the relationship between the supercharging pressure and the rotational speed of the electric supercharger 24 (electric compressor 24a), and FIG. The relationship between a rotational speed and the applied voltage of the electric motor 24b is shown.

  The waveform of the acceleration G indicated by a broken line in FIG. 4 is for acceleration without electric assist (hereinafter referred to as “base acceleration” for convenience of explanation). More specifically, FIG. 4 shows a case where the accelerator pedal is depressed from the small accelerator opening range where the accelerator opening is less than a predetermined value toward the accelerator opening greater than the predetermined value.

  Explaining the trajectory of the time change of the acceleration G in the base acceleration, except for the period before the time point t1, the acceleration G increases in accordance with the number of second order in the initial stage of acceleration, and then increases in accordance with the linear function. It becomes the characteristic to do. Such characteristics themselves are basically the same for “base acceleration” that does not involve electric assist in a naturally aspirated engine that is not equipped with the turbocharger 22, although there is a difference in the degree of rising of the acceleration G. is there.

  In FIG. 4, a time point at which the function that the locus of the acceleration G of the base acceleration follows changes from a quadratic function to a linear function is “t4”. According to the above characteristics of the base acceleration, in the period from the time point t1 to the time point t4, a trajectory in which the acceleration G increases according to a quadratic function, that is, a trajectory in which the time change rate R of the jerk ΔG is constant is obtained. It can be said that. Therefore, in the present control method, the motor 24b is energized during the initial acceleration period from the acceleration request time t0 to less than the time t4 (that is, the period until the acceleration G finishes increasing according to the quadratic function in the base acceleration). There is no delay time td. In addition, as control of the electric supercharger for improving acceleration response, the rotational speed of the electric supercharger is set in advance by operating the electric supercharger with the bypass valve corresponding to the intake bypass valve 26 opened. Pre-rotation control to be increased is known. Unlike the present embodiment, if such pre-rotation control is used, energization for pre-rotation is performed without waiting for the elapse of the delay time td. If only the energization is performed, supercharging (intake air) by the electric motor is not started.

  In addition, during a period from time t4 to time t5, that is, a period in which the acceleration G increases in accordance with the linear function in the base acceleration, the motor 24b is supplied to the electric motor 24b so that the rotational speed of the electric supercharger 24 increases in accordance with the quadratic function. Is controlled. That is, supercharging by the electric motor 24b is started at time t4. Here, as shown in FIGS. 5 to 7, the acceleration G, the supercharging pressure (intake manifold pressure), the rotational speed of the electric supercharger 24, and the applied voltage are correlated. For this reason, the energization control for increasing the rotational speed of the electric supercharger 24 according to the quadratic function is, for example, during a period from time t4 to time t5 (hereinafter referred to as “voltage application period”). It is possible to adjust the applied voltage so as to increase from zero according to a quadratic function. As a result, the boost pressure can be increased according to a quadratic function during the voltage application period. According to the above correlation, when the supercharging pressure increases according to a quadratic function, the acceleration G also increases according to the quadratic function. Therefore, by adding an increase in the quadratic function acceleration G by the electric assist to the locus of the acceleration G of the base acceleration that increases in a linear function, as shown by a solid line in FIG. The final locus of the acceleration G during the application period can also be increased in a quadratic function over time.

  More specifically, in order to realize acceleration in which the time change rate R of the jerk ΔG can be made to be constant by using the electric assist, the time point t1 or higher at which the acceleration G increases by a quadratic function by base acceleration. It is necessary to make the time change rate R of the jerk ΔG the same between the period up to the time point t4 and the subsequent voltage application period. For this reason, during the voltage application period, a voltage is applied to the motor 24b so that the secondary coefficient increases according to a quadratic function selected so as to satisfy the above-described necessity.

(Change of time rate of change R of jerk ΔG according to accelerator opening)
FIG. 8 is a time chart for explaining the difference according to the accelerator opening degree with respect to the time change locus of the acceleration G for the base acceleration without the electric assist. Each trajectory of the acceleration G shown in FIG. 8 is obtained when the accelerator pedal is depressed from a small accelerator opening range where the accelerator opening is less than a predetermined value toward an accelerator opening greater than the predetermined value.

  The basic characteristics of the trajectory of the acceleration G in the base acceleration (that is, the acceleration G increases in a quadratic function in the initial stage of acceleration and thereafter increases in a linear function) are the same regardless of the accelerator opening. is there. In addition, the trajectory of the acceleration G of the base acceleration shows a tendency that the acceleration G rises more rapidly as the accelerator opening after the depression is larger. More specifically, the larger the accelerator opening, the earlier the time point t4 at which the function that the locus of the acceleration G of the base acceleration follows from the quadratic function to the linear function. Further, the larger the accelerator opening, the larger the quadratic coefficient of the quadratic function during the period in which the acceleration G shows a quadratic function increase. The tendency of the change in the locus of the acceleration G of the base acceleration according to the accelerator opening as shown in FIG. 8 is large when the acceleration is requested in the configuration of the internal combustion engine 10 of the present embodiment. This is realized by the fact that the opening degree of the WGV 34 is more closed.

  FIG. 9 is a time chart for explaining a method of controlling the time change locus of the acceleration G by using the electric assist so that the locus corresponds to the accelerator opening. As already described with reference to FIG. 8, in the internal combustion engine 10 of the present embodiment, the trajectory of the acceleration G in the base acceleration differs depending on the accelerator opening. If there is such a premise, if the same delay time td and applied voltage waveform are uniformly used regardless of the accelerator opening, the time change rate R of the jerk ΔG during the acceleration period cannot be kept constant. There is a case. Therefore, in the present embodiment, when acceleration is requested, in order to realize the electric assist of acceleration that can make the time change rate R of the jerk ΔG more appropriately close to constant regardless of the accelerator opening, It was decided to perform such control. That is, in consideration of the characteristics of the base acceleration described with reference to FIG. 8, the time change rate R of the jerk ΔG is constant at a larger value as the accelerator opening when acceleration is required is larger. Thus, the trajectory of the time change of the acceleration G is controlled.

  Specifically, as described above, the time point t4 is earlier as the accelerator opening is larger. Therefore, in this embodiment, the delay time is shortened as the accelerator opening when acceleration is requested is larger. In addition, as described above, the quadratic coefficient of the quadratic function at the initial stage of the base acceleration acceleration G becomes larger as the accelerator opening is larger. Therefore, in this embodiment, when acceleration is required, a quadratic coefficient associated with the quadratic coefficient of the acceleration G of the base acceleration is used as the quadratic coefficient of the quadratic function that the applied voltage waveform follows. In addition, the voltage applied to the electric motor 24b is controlled so that the quadratic coefficient increases according to a larger quadratic function as the accelerator opening is larger.

(Change of the time change locus of the acceleration G according to the shift position)
FIG. 10 is a time chart showing an example of the difference in the trajectory of the time change of the acceleration G due to the difference in the shift position. In FIG. 10, the second speed gear and the fourth speed gear are exemplified for the base acceleration, and the difference in the locus of the acceleration G corresponding to the shift position is shown. As shown in FIG. 10, the higher the speed ratio of the transmission, the larger the maximum value of the acceleration G reached during acceleration in the base acceleration. Therefore, in this embodiment, when an acceleration request is issued, the energization to the electric motor 24b is controlled so that the higher the gear ratio, the higher the rotational speed of the electric supercharger 24 that is reached during acceleration. It was. More specifically, in such energization control, the higher the gear ratio, the higher the maximum applied voltage to the motor 24b.

(Control of trajectory of acceleration G with respect to change in accelerator opening during acceleration)
FIG. 11 is a time chart for explaining the control of the trajectory of the time change of the acceleration G, which is executed when the accelerator pedal is further depressed during acceleration. More specifically, in the control example shown in FIG. 11, when the accelerator pedal is further depressed at time t <b> 6 during acceleration in which electric assist is performed using the control method described with reference to FIG. 4. belongs to. In addition, the waveform shown with a broken line in FIG. 11 is a thing when stepping on an accelerator pedal is not performed.

  In the present embodiment, in order to realize acceleration that better matches the driver's acceleration request, the following control is executed when the accelerator pedal is depressed at time t6. That is, in order to obtain a trajectory of acceleration G in which the time change rate R of the jerk ΔG is larger, the application voltage is applied so that the applied voltage to the motor 24b increases according to a quadratic function having a larger second-order coefficient. The voltage waveform is corrected. More specifically, the second-order coefficient of the applied voltage waveform is increased as the accelerator opening after stepping on is increased. According to such control, the quadratic coefficient of the quadratic function followed by the locus of the acceleration G is increased so as to have a value corresponding to the accelerator opening after stepping on. As a result, acceleration that better matches the driver's acceleration request can be realized.

  When the accelerator pedal is stepped back during acceleration, the acceleration may be continued depending on the timing and amount of stepping back. Therefore, in this embodiment, in such a case, the secondary coefficient of the applied voltage waveform is reduced. More specifically, on the condition that the acceleration is continued, the second order coefficient is made smaller as the accelerator opening after stepping back is smaller.

  Although not shown in FIG. 11, the accelerator opening may be changed during the elapse of the delay time td after the acceleration starts. In this embodiment, in such a case, the delay time td is updated so as to be a time corresponding to the changed accelerator opening. More specifically, the delay time td is shortened as the accelerator opening after the change is large, and conversely, the delay time td is lengthened as the accelerator opening after the change is small. However, if the accelerator pedal is further depressed, it may not be possible to correct the delay time td to be short, depending on the elapsed time from the acceleration request. In such a case, voltage application is started at the time when the stepping-in is increased.

(Specific processing in Embodiment 1)
FIG. 12 is a flowchart showing a flow of the electric assist control during acceleration in the first embodiment of the present invention. As shown in FIG. 12, the ECU 40 first acquires the accelerator opening and the shift position using the accelerator position sensor 44 and the shift position sensor 48 in step 100.

  Next, the ECU 40 proceeds to step 102. In step 102, it is determined whether or not the accelerator opening is equal to or greater than a predetermined value. This predetermined value is a value set in advance as a threshold value of the accelerator opening for determining whether or not acceleration requiring electric assist is requested when the accelerator pedal is depressed. While the accelerator opening is less than the predetermined value, the ECU 40 returns to step 100 and acquires the accelerator opening and the like again according to a predetermined sampling cycle. Therefore, when the accelerator pedal is depressed from the state where the accelerator opening is less than the predetermined value so that the accelerator opening becomes equal to or larger than the predetermined value, and the determination of this step 102 is established accordingly, the electric assist is required. It can be determined that acceleration is required. In response to the detection of such an acceleration request, the throttle valve 30 is fully opened and the WGV 34 is closed at an opening corresponding to the accelerator opening. By such a predetermined acceleration operation, acceleration of the vehicle is quickly started.

  If the determination in step 102 is established, the ECU 40 proceeds to step 104. In step 104, counting of the elapsed time t from the time when the determination in step 102 is satisfied (that is, the current acceleration request time t0) is started.

  Next, the ECU 40 proceeds to step 106. In step 106, the delay time td corresponding to the accelerator opening acquired in step 100 or step 110 described later is calculated with reference to the following map. FIG. 13 is a diagram showing the characteristics of a map in which the relationship between the accelerator opening and the delay time td is determined in advance. As shown in FIG. 13, in this map, the delay time td is set to be shorter as the accelerator opening is larger. Such map characteristics can be obtained by the following method. That is, as shown in FIG. 8, the trajectory of the time change of the acceleration G in the base acceleration can be simulated using a quadratic function and a linear function. And the locus | trajectory of the acceleration G of the base acceleration according to the accelerator opening as shown in FIG. 8 can be acquired beforehand by experiment etc. Specifically, the trajectory of the acceleration G in base acceleration is targeted when the accelerator pedal is depressed from the small accelerator opening range where the accelerator opening is less than a predetermined value toward the accelerator opening greater than the predetermined value. Obtained by using an acceleration sensor or the like for each predetermined accelerator opening. Then, the obtained trajectories are approximated using a quadratic function and a linear function. According to the trajectories obtained in this way, the time point t4 when the function that the trajectory follows changes from a quadratic function to a linear function can be acquired for each accelerator opening. Therefore, the delay time td according to the accelerator opening can be acquired.

  Next, the ECU 40 proceeds to step 108. In step 108, it is determined whether the elapsed time t from the current acceleration request is longer than the delay time td. While the determination in step 108 is not satisfied, that is, while the delay time td has elapsed, the ECU 40 proceeds to step 110 and acquires the accelerator opening again according to the sampling period. Next, the ECU 40 proceeds to step 112. In step 112, it is determined whether or not the vehicle is accelerating by determining a change in the vehicle speed using the vehicle speed sensor 46. As a result, if this determination is not satisfied, that is, if the acceleration is changed to deceleration with a change in the accelerator opening, the current electric assist control is promptly terminated. On the other hand, when the above determination is established, the ECU 40 proceeds to step 106. The situation where the routine proceeds to step 106 in this order is that the accelerator opening when the determination of step 102 is initially established is maintained, the accelerator opening is increased (the accelerator pedal is further depressed). Or when the accelerator opening is decreased within a range where acceleration continues (when the accelerator pedal is stepped back). In step 106, if the initial accelerator opening is maintained, the delay time td is maintained at the initially calculated value (that is, not updated). On the other hand, when the accelerator pedal is stepped on or returned, the delay time td is updated with reference to the map shown in FIG. 13 so as to have a value corresponding to the changed accelerator opening.

  If the determination in step 108 is established, that is, if the elapsed time t is longer than the delay time td, the ECU 40 proceeds to step 114. In step 114, an applied voltage waveform is calculated based on the acquired latest accelerator opening and shift position. The applied voltage waveform referred to here is a waveform of a voltage applied to the motor 24b during the voltage application period shown in FIG. In this applied voltage waveform, the trajectory of the acceleration G after the lapse of the delay time td is a trajectory of the same quadratic function as the trajectory of the quadratic function with the time change rate R of the jerk ΔG. This is the waveform of the applied voltage necessary for this. That is, the applied voltage waveform is a waveform of the applied voltage necessary for raising the acceleration G by the area indicated by hatching in FIG. 4, and the voltage application start timing by this applied voltage waveform is the delay time. It changes according to td. As described above, a simulated trajectory of the acceleration G of the base acceleration can be obtained by experiments or the like. It is also possible to calculate a quadratic function locus of acceleration G in which the rate of change R of jerk ΔG is the same as the locus of the quadratic function during the lapse of the delay time td. Therefore, based on these two loci, it is possible to calculate the applied voltage at each time point necessary to fill the difference between these loci, and as a result, it is possible to calculate the applied voltage waveform. Since the quadratic coefficient of the quadratic function followed by the base acceleration trajectory increases as the accelerator opening increases, the applied voltage waveform increases as the accelerator opening increases as the accelerator opening increases. The waveform follows a quadratic function with a large coefficient.

  The calculation of the applied voltage waveform may be performed on-board, but here, the applied voltage waveform is calculated in advance, and the calculated applied voltage waveform is set as a different waveform depending on the accelerator opening. It is assumed that the map is stored in the ECU 40. In step 114, a necessary voltage waveform corresponding to the accelerator opening is calculated with reference to such a map. The required voltage waveform stored in this map has a maximum applied voltage that varies depending on the shift position. More specifically, in this map, the maximum applied voltage at each accelerator opening is set higher as the gear ratio grasped based on the shift position is higher.

  Next, the ECU 40 proceeds to step 116. In step 116, a voltage is applied to the motor 24b according to the applied voltage waveform calculated in step 114. More specifically, this voltage application is started immediately after the determination in step 108 is established, that is, after the delay time td has elapsed. Next, the ECU 40 proceeds to step 118. In step 118, it is determined whether or not the accelerator opening is changed.

  If it is determined in step 118 that the accelerator opening is not changed, the ECU 40 proceeds to step 120. In step 120, it is determined whether the voltage applied according to the applied voltage waveform has reached the maximum applied voltage. As a result, voltage application is continued while this determination is not satisfied. On the other hand, when this determination is established, the current electric assist control is terminated.

  On the other hand, when it is determined in step 118 that the accelerator opening is changed, the ECU 40 proceeds to step 122. In step 122, it is determined whether or not the vehicle is accelerating using the same processing as in step 112. As a result, if this determination is not satisfied, that is, if the acceleration is changed to deceleration with a change in the accelerator opening, the current electric assist control is promptly terminated.

  On the other hand, when the determination in step 122 is established, the ECU 40 returns to step 114. As a result, in step 114, an applied voltage waveform (hereinafter referred to as “corrected voltage waveform”) corresponding to the changed accelerator opening is calculated. Hereinafter, an example of a method for calculating the corrected voltage waveform will be described by taking as an example a case where the accelerator pedal is depressed. As described above, the trajectory of the acceleration G of the base acceleration changes according to the accelerator opening (see FIG. 8). The ECU 40 stores a relationship between the trajectory of the acceleration G of the base acceleration and the accelerator opening as a map. According to this map, when the accelerator pedal is further depressed, a linear function that follows the locus of the acceleration G of the base acceleration corresponding to the accelerator opening after the depression of the accelerator pedal can be acquired. Here, the trajectory of the acceleration G of the base acceleration in a period after the time t6 (see FIG. 11) when the accelerator pedal is increased is expressed as “L” in FIG. 11 using the linear function acquired as described above. It is acquired as a straight line indicated with “”. This trajectory (straight line L) corresponds to a potential trajectory of the acceleration G that can be raised by supercharging by the turbocharger 22 after the accelerator pedal is stepped on. Further, as the accelerator opening is larger, the quadratic coefficient of the quadratic function that follows the trajectory of the acceleration G of the base acceleration becomes larger. The ECU 40 stores a map (not shown) that defines the relationship between the accelerator opening and the secondary coefficient of base acceleration. According to this map, the quadratic coefficient of the quadratic function followed by the trajectory of the acceleration G to be realized using the electric assist in the period after the time point t6 is a value associated with the trajectory of the acceleration G of the base acceleration. And can be obtained as a value corresponding to the accelerator opening. Then, the locus of the quadratic function using the acquired quadratic coefficient can be obtained as a curve denoted by “C” in FIG. Based on these two loci (curve C and straight line L), the ECU 40 calculates an applied voltage at each time point necessary to fill the difference between these loci. By such a method, it is possible to calculate a corrected voltage waveform that increases in a quadratic function over time. Here, the calculation of the corrected voltage waveform when the accelerator pedal is stepped on has been described, but the corrected voltage waveform when the accelerator pedal is depressed within the range where acceleration continues is calculated in the same way. can do.

(Effect of electric assist control of Embodiment 1)
According to the electric assist control of the present embodiment described with reference to FIG. 12, when the acceleration of the vehicle accompanied by the electric assist is requested, the energization to the electric motor 24b is delayed until the delay time td from the acceleration start elapses. Is done. And after delay time td passes, a voltage is applied to the electric motor 24b according to the applied voltage waveform. This applied voltage waveform is a quadratic function with respect to time, and the voltage increases according to a quadratic function having a positive quadratic coefficient. In the initial stage of base acceleration, the acceleration G increases according to a quadratic function. Therefore, by appropriately setting the delay time td by the method of the present embodiment (more specifically, the delay time td is set so that the acceleration G finishes rising according to the quadratic function in the base acceleration). By using the characteristics of the base acceleration in the early stage of acceleration, the time change rate R of the jerk ΔG can be made almost constant over time in the early stage of acceleration without consuming electric power of the electric motor 24b. In addition, during the period when the acceleration G of the base acceleration subsequently increases according to the linear function, the rotational speed of the electric supercharger 24 is controlled by controlling the energization to the electric motor 24b so that the applied voltage increases according to the quadratic function. Can be increased in a quadratic function, and as a result, the final acceleration G can also be increased in a quadratic function. As a result, during the period in which the acceleration G rises during acceleration, the time change rate R of the jerk ΔG can be made constant over time. From the above, according to the control of the present embodiment, when using the electric assist to increase the acceleration responsiveness over the base acceleration, acceleration with a sense of sustainability (a sense of growth) is taken into account while increasing the power consumption. Can be realized.

  Further, according to the control of the present embodiment, the delay time td is shortened as the accelerator opening when the acceleration of the vehicle is requested is larger. Thereby, in the internal combustion engine 10 in which the trajectory of the acceleration G of the base acceleration changes according to the accelerator opening as shown in FIG. 8, the delay time td is set so as to be an appropriate time according to the accelerator opening. be able to. Specifically, it is possible to make the time change rate R of the jerk ΔG closer to a constant value in the initial stage of acceleration while more effectively using the acceleration characteristics of the base acceleration to suppress an increase in power consumption. Furthermore, the following effects can be given as an effect of changing the delay time td in accordance with the accelerator opening. That is, according to this setting, when the accelerator opening is reduced, the delay time td is lengthened. When the delay time td becomes longer, the work performed by the turbocharger 22 during the delay time td increases because the number of superchargers that operate is reduced compared to the case where electric assist is performed at the same timing. Therefore, when the delay time td is lengthened, as shown in FIG. 9, the maximum applied voltage required to reach the same acceleration G during acceleration can be lowered. From this, it can be said that the control method of the present embodiment is excellent in that it suppresses an increase in power consumption when reaching the same acceleration G. And according to this control method, the acceleration characteristic which can change the time required until the acceleration G reaches | attains the maximum value at the time of acceleration according to accelerator opening can also be implement | achieved by adjustment of the delay time td.

  Further, according to the control of the present embodiment, when the accelerator opening is changed during the lapse of the delay time td, the delay time td is updated so as to become shorter as the accelerator opening after the change is larger. Thereby, in the internal combustion engine 10 in which the trajectory of the acceleration G of the base acceleration changes according to the accelerator opening as shown in FIG. 8, the delay time td is set to an appropriate time according to the changed accelerator opening. Can be corrected.

  Further, according to the control of the present embodiment, when acceleration of the vehicle is requested, the quadratic coefficient of the quadratic function that the applied voltage waveform follows increases as the accelerator opening increases. As a result, in the internal combustion engine 10 in which the trajectory of the acceleration G of the base acceleration changes according to the accelerator opening as shown in FIG. 8, the initial (trajectory of the trajectory of the acceleration G of the base acceleration does not depend on the accelerator opening. It is possible to achieve acceleration by adjusting the time change rate R of the jerk ΔG after the start of the electric assist so that the time change rate R of the jerk ΔG in the period according to the quadratic function can be approximated. According to such electric assist, the time change rate R of the jerk ΔG can be made closer to a constant with a larger value as the accelerator opening is larger, so that the acceleration G increases as the accelerator opening increases. The rise can be sharpened. For this reason, the driving | running | working near a driver | operator's intent becomes possible.

  Further, according to the control of the present embodiment, when the accelerator opening is changed during acceleration of the vehicle, the quadratic coefficient of the quadratic function that the applied voltage waveform follows as the changed accelerator opening is larger. Is increased. Thereby, in the internal combustion engine 10 in which the locus of the acceleration G of the base acceleration changes according to the accelerator opening as shown in FIG. 8, the time change of the jerk ΔG with a value according to the changed accelerator opening. The trajectory of the acceleration G can be appropriately corrected so that the rate R can be kept constant.

  Further, according to the control of the present embodiment, the maximum applied voltage in the applied voltage waveform is increased as the gear ratio used when acceleration of the vehicle is required is increased. As a result, the maximum value of the rotational speed (that is, acceleration G) of the electric supercharger 24 that is achieved with electric assist during acceleration is increased. Thereby, since the acceleration G obtained according to the shift position selected by the driver can be changed, it is possible to travel close to the driver's intention.

  In the first embodiment described above, the “electric motor control means” according to the present invention is realized by the ECU 40 executing a series of processes in the flowchart shown in FIG.

  By the way, in Embodiment 1 mentioned above, when acceleration is requested | required, the maximum applied voltage in an applied voltage waveform is enlarged, so that gear ratio is high. On the other hand, the higher the gear ratio, the earlier the time point t4 (see FIG. 4). Therefore, when acceleration is requested, the delay time td may be shortened as the gear ratio increases. Further, the higher the gear ratio, the larger the quadratic coefficient of the quadratic function at the initial stage of the base acceleration acceleration G. Therefore, even when the acceleration is required, the voltage applied to the electric motor 24b is controlled such that the higher the gear ratio, the higher the quadratic coefficient increases according to a larger quadratic function. Good.

  In the first embodiment described above, the internal combustion engine 10 that includes the electric supercharger 24 that uses only the electric power from the electric motor 24b as a power source and the turbocharger 22 that uses exhaust energy as a power source is taken as an example. I explained. However, the electric supercharger included in the internal combustion engine according to the present invention is not limited to the one having the above-described configuration, and is an electric assist turbocharger that is a single supercharger that uses electric power and exhaust energy from the electric motor as power sources. Alternatively, there may be only an electric supercharger that uses only electric power from the electric motor as a power source.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Internal combustion engine main body 14 Intake passage 14a Main intake passage 14b Intake bypass passage 14c Intake manifold 16 Exhaust passage 16a Exhaust manifold 16b Exhaust bypass passage 18 Air cleaner 20 Air flow meter 22 Turbo supercharger 22a Turbo compressor 22b Turbine 24 Electric supercharger Machine 24a Electric compressor 24b Electric motor 26 Intake bypass valve 28 Intercooler 30 Throttle valve 32 Intake pressure sensor 34 Waste gate valve (WGV)
40 ECU (Electronic Control Unit)
42 Crank angle sensor 44 Accelerator position sensor 46 Vehicle speed sensor 48 Shift position sensor 50 Fuel injection valve 52 Ignition device

(Necessity to control time-varying trajectory of acceleration G during acceleration)
In the present embodiment, electric assist is used to assist supercharging by the turbocharger 22 during vehicle acceleration. According to the acceleration assist by the electric assist, the acceleration response of the internal combustion engine 10 can be improved. However, electric power is required to operate the electric motor 24b for assisting acceleration. More specifically, in order to obtain this electric power, it is necessary to generate power using an alternator (not shown) provided in the internal combustion engine 10 or the like. The alternator generates power using the power of the internal combustion engine 10. The electric power generated by the alternator is supplied to the electric motor 24b via the battery described above. As described above, when the power of the internal combustion engine 10 is used for power generation, an increase in power consumption of the electric motor 24b leads to a deterioration in fuel consumption of the internal combustion engine 10. Therefore, when assisting the acceleration of the vehicle by the electric assist, if the maximum electric power that can be supplied to the electric motor 24b is always given as shown by the solid line in FIG. 2, the following situation is concerned. . That is, according to the acceleration with the maximum electric assist, the time required to reach the same acceleration G is shortened as compared with the acceleration without the electric assist, that is, the acceleration response can be sufficiently improved. On the other hand, even if the acceleration response can be sufficiently increased, the amount of power consumption increases and the fuel consumption may deteriorate. In FIG. 2, the acceleration G is constant during a period from time t3 to time t2 in acceleration with maximum electric assist. For this reason, this acceleration is weak in sustainability (elongation) compared to acceleration without electric assist.

In FIG. 4, a time point at which the function that the locus of the acceleration G of the base acceleration follows changes from a quadratic function to a linear function is “t4”. According to the above characteristics of the base acceleration, in the period from the time point t1 to the time point t4, a trajectory in which the acceleration G increases according to a quadratic function, that is, a trajectory in which the time change rate R of the jerk ΔG is constant is obtained. It can be said that. Therefore, in the present control method, the motor 24b is energized during the initial acceleration period from the acceleration request time t0 to less than the time t4 (that is, the period until the acceleration G finishes increasing according to the quadratic function in the base acceleration). There is no delay time td. In addition, as control of the electric supercharger for improving acceleration response, the rotational speed of the electric supercharger is set in advance by operating the electric supercharger with the bypass valve corresponding to the intake bypass valve 26 opened. Pre-rotation control to be increased is known. Unlike the present embodiment, if such pre-rotation control is used, energization for pre-rotation is performed without waiting for the elapse of the delay time td. If only the energization is performed, supercharging (intake air) by the electric motor is not started. In other words, supercharging in this case is started when energization for supercharging is started when the delay time td has elapsed and the bypass valve is closed.

Next, the ECU 40 proceeds to step 116. In step 116, a voltage according to the applied voltage waveform calculated in step 114 is applied to the electric motor 24b , and the intake bypass valve 26 is closed . More specifically, this voltage application is started immediately after the determination in step 108 is established, that is, after the delay time td has elapsed. Next, the ECU 40 proceeds to step 118. In step 118, it is determined whether or not the accelerator opening is changed.

On the other hand, when the determination in step 122 is established, the ECU 40 returns to step 114. As a result, in step 114, an applied voltage waveform (hereinafter referred to as “corrected voltage waveform”) corresponding to the changed accelerator opening is calculated , and the intake bypass valve 26 is maintained in the closed state . Hereinafter, an example of a method for calculating the corrected voltage waveform will be described by taking as an example a case where the accelerator pedal is depressed. As described above, the trajectory of the acceleration G of the base acceleration changes according to the accelerator opening (see FIG. 8). The ECU 40 stores a relationship between the trajectory of the acceleration G of the base acceleration and the accelerator opening as a map. According to this map, when the accelerator pedal is further depressed, a linear function that follows the locus of the acceleration G of the base acceleration corresponding to the accelerator opening after the depression of the accelerator pedal can be acquired. Here, the trajectory of the acceleration G of the base acceleration in a period after the time t6 (see FIG. 11) when the accelerator pedal is increased is expressed as “L” in FIG. 11 using the linear function acquired as described above. It is acquired as a straight line indicated with “”. This trajectory (straight line L) corresponds to a potential trajectory of the acceleration G that can be raised by supercharging by the turbocharger 22 after the accelerator pedal is stepped on. Further, as the accelerator opening is larger, the quadratic coefficient of the quadratic function that follows the trajectory of the acceleration G of the base acceleration becomes larger. The ECU 40 stores a map (not shown) that defines the relationship between the accelerator opening and the secondary coefficient of base acceleration. According to this map, the quadratic coefficient of the quadratic function followed by the trajectory of the acceleration G to be realized using the electric assist in the period after the time point t6 is a value associated with the trajectory of the acceleration G of the base acceleration. And can be obtained as a value corresponding to the accelerator opening. Then, the locus of the quadratic function using the acquired quadratic coefficient can be obtained as a curve denoted by “C” in FIG. Based on these two loci (curve C and straight line L), the ECU 40 calculates an applied voltage at each time point necessary to fill the difference between these loci. By such a method, it is possible to calculate a corrected voltage waveform that increases in a quadratic function over time. Here, the calculation of the corrected voltage waveform when the accelerator pedal is stepped on has been described, but the corrected voltage waveform when the accelerator pedal is depressed within the range where acceleration continues is calculated in the same way. can do.

(Effect of electric assist control of Embodiment 1)
According to the electric assist control of the present embodiment described with reference to FIG. 12, when the acceleration of the vehicle accompanied by the electric assist is requested, the energization to the electric motor 24b is delayed until the delay time td from the acceleration start elapses. Is done. And after delay time td passes, a voltage is applied to the electric motor 24b according to the applied voltage waveform. This applied voltage waveform is a quadratic function with respect to time, and the voltage increases according to a quadratic function having a positive quadratic coefficient. In the initial stage of base acceleration, the acceleration G increases according to a quadratic function. Therefore, by appropriately setting the delay time td by the method of the present embodiment (more specifically, the delay time td is set so that the acceleration G finishes rising according to the quadratic function in the base acceleration). By using the characteristics of the base acceleration in the early stage of acceleration, the time change rate R of the jerk ΔG can be made almost constant over time in the early stage of acceleration without consuming electric power of the electric motor 24b. In addition, during the period when the acceleration G of the base acceleration subsequently increases according to the linear function, the rotational speed of the electric supercharger 24 is controlled by controlling the energization to the electric motor 24b so that the applied voltage increases according to the quadratic function. Can be increased in a quadratic function, and as a result, the final acceleration G can also be increased in a quadratic function. As a result, during the period in which the acceleration G rises during acceleration, the time change rate R of the jerk ΔG can be made constant over time. From the above, according to the control of the present embodiment, when using the electric assist to increase the acceleration responsiveness over the base acceleration, acceleration with a sense of sustainability (a sense of growth) is taken into account while increasing the power consumption. Can be realized. In addition, when accompanying the pre-rotation control mentioned above, the following processes are performed, for example in connection with the process according to the flowchart of FIG. That is, when the determination in step 102 is established (when an acceleration request is detected), energization to the motor 24b is started for pre-rotation. The energization for the pre-rotation is executed until the determination in step 108 is established, and after the determination in step 108 is established, the energization for supercharging is performed.

Claims (7)

A control device for an internal combustion engine that controls an internal combustion engine comprising an electric supercharger having a compressor that supercharges intake air and an electric motor that can drive the compressor,
Electric motor control means for controlling energization of the electric motor,
The motor control means is configured to control the motor when the vehicle equipped with the internal combustion engine is requested to accelerate with the assistance of the electric supercharger and when the delay time from the start of acceleration of the vehicle has elapsed. To the motor after the supercharging is started so that the rotation speed of the compressor is increased according to a quadratic function that starts supercharging and is a quadratic function with respect to time and a positive quadratic coefficient. A control apparatus for an internal combustion engine, characterized by controlling energization.   2. The control apparatus for an internal combustion engine according to claim 1, wherein the delay time is shorter as the accelerator opening of the accelerator pedal is larger when acceleration of the vehicle is requested.   When the accelerator opening of the accelerator pedal is changed during the lapse of the delay time, the electric motor control means updates the delay time so as to become shorter as the accelerator opening after the change is larger. The control apparatus for an internal combustion engine according to claim 1 or 2.   When the acceleration of the vehicle is requested, the motor control means sets the second-order coefficient used for controlling energization to the motor to a larger value as the accelerator opening of the accelerator pedal is larger. The control device for an internal combustion engine according to any one of claims 1 to 3.   When the accelerator opening of the accelerator pedal is changed during acceleration of the vehicle, the motor control means is configured to use the second order coefficient used for controlling energization of the motor as the changed accelerator opening is larger. The internal combustion engine control apparatus according to any one of claims 1 to 4, wherein the value is corrected to a larger value.   The motor control means energizes the motor so that the higher the gear ratio of the vehicle used when acceleration of the vehicle is required, the higher the rotational speed of the compressor reached during acceleration. 6. The control device for an internal combustion engine according to claim 1, wherein:   7. The delay time is a period until acceleration finishes increasing according to a quadratic function in acceleration of the vehicle without assistance by the electric motor. Control device for internal combustion engine.

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