VEHICLE CONTROL DEVICE

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2021-052252 filed on Mar. 25, 2021, the contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a vehicle control device.

BACKGROUND

In the related art, a fuel cut control for stopping fuel supply to an internal combustion engine is executed in order to improve fuel consumption performance of a vehicle including an internal combustion engine.

JP-A-2002-247708 discloses a hybrid vehicle including an engine that can be switched between a normal operation and a cylinder deactivation operation and serves as a drive source of the vehicle and a motor that performs driving assistance of the engine in accordance with an operating state of the vehicle, and discloses a technique in which the motor performs the driving assistance of the engine at the time of transition from the cylinder deactivation operation to the normal operation. JP-A-2003-083104 discloses a technique in which a starting torque for starting an engine by a motor when the engine is returned from a deactivated-cylinder state is lower than a normal starting torque.

When a vehicle including an internal combustion engine, an electric motor coupled to the internal combustion engine, and a drive wheel coupled to the internal combustion engine and the electric motor via a power transmission device is braked (that is, at the time of decelerating the vehicle), the electric motor can perform regenerative power generation. At this time, when a loss of the internal combustion engine relative to power input from the drive wheel can be reduced, a regenerative torque input to the electric motor can be increased, and a power generation amount of the electric motor can be increased. Therefore, it is conceivable to reduce a pumping loss of the internal combustion engine and increase the regenerative torque by opening a throttle of the vehicle when a fuel cut control is executed in response to a deceleration request. In such a case, responsiveness to a subsequent acceleration request and noise and vibration (NV) characteristics of the vehicle in the related art can be improved.

The present disclosure provides a vehicle control device that can prevent the deterioration of NV characteristics of a vehicle while ensuring responsiveness of the vehicle to an acceleration request after a deceleration request.

SUMMARY

A vehicle control device for controlling a vehicle that includes an internal combustion engine, an electric motor coupled to the internal combustion engine, and a drive wheel coupled to the internal combustion engine and the electric motor via a power transmission device and that is configured to execute a motor assist for assisting driving of the drive wheel by power of the electric motor. The power transmission device includes a torque converter, a lock-up clutch, and a main shaft configured to output, to the drive wheel, power of at least one of the internal combustion engine and the electric motor transmitted via at least one of the torque converter and the lock-up clutch. The vehicle control device is configured to: execute a fuel cut control for stopping fuel supply to the internal combustion engine in response to a deceleration request to the vehicle; disengage the lock-up clutch and open a throttle of the vehicle during the execution of the fuel cut control; execute the motor assist in a case where there is an acceleration request to the vehicle while the lock-up clutch is disengaged and the throttle is opened; and execute a motor torque reduction control for temporarily reducing an output from the electric motor based on a rotation speed of the internal combustion engine and a rotation speed of the main shaft during the execution of the motor assist.

According to the present disclosure, it is possible to provide a vehicle control device that can prevent the deterioration of NV characteristics of a vehicle while ensuring vehicle responsiveness to an acceleration request after a deceleration request.

BRIEF DESCRIPTION OF DRAWINGS

Exemplary embodiments of the present disclosure will be described in detail based on the following figures, wherein:

FIG. 1 is a diagram showing an example of a vehicle according to an embodiment:

FIG. 2 is a diagram showing an example of a transmission provided in the vehicle according to the embodiment; and

FIG. 3 is a diagram showing a specific example of a control executed by a control device according to the embodiment.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of a vehicle control device according to the present disclosure will be described in detail with reference to the drawings.

[Vehicle]

As shown in FIG. 1, a vehicle 1 according to the present embodiment is a so-called hybrid electrical vehicle, and includes an engine 11 that is an example of an internal combustion engine, a motor generator 12 that is an example of an electric motor, a transmission TM that is an example of a power transmission device, a drive wheel DW, a battery 20, a power conversion device 21, and a control device 30 that controls the entire vehicle 1. The control device 30 is an example of a vehicle control device according to the present disclosure. In FIG. 1, a thick solid line indicates mechanical coupling, double broken lines indicate electric wiring, and a solid arrow indicates a control signal.

The engine 11 is, for example, a so-called cylinder deactivation engine configured to be switchable between an all-cylinder operation in which all cylinders can be operated and a deactivated-cylinder operation in which some cylinders can be deactivated. For example, the engine 11 is a V-type six-cylinder engine including a variable valve timing mechanism (not shown), and is configured such that three cylinders of one bank can be deactivated by the variable valve timing mechanism. That is, in the engine 11, a six-cylinder operation using six cylinders of both banks is performed during an all-cylinder operation, and a three-cylinder operation using only three cylinders of one bank is performed during a deactivated-cylinder operation. For example, the engine 11 is configured such that a valve opening period, a valve opening and closing timing, a lift amount, and the like of each intake valve can be changed by the variable valve timing mechanism.

The engine 11 outputs mechanical energy (power) generated by burning supplied fuel (for example, gasoline) by rotationally driving a crankshaft 11a (see FIG. 2). Specifically, the engine 11 includes an injector (not shown). The injector is controlled by the control device 30 using, for example, a pulse width modulation (PWM) control, and supplies fuel to the engine 11. Power output from the engine 11 by a fuel supply is transmitted to the drive wheel DW via the transmission TM that is mechanically coupled to the engine 11, and the power is used for traveling of the vehicle 1.

The engine 11 is also mechanically coupled to the motor generator 12. The motor generator 12 is, for example, a three-phase AC motor, and functions as an electric motor that outputs power by being supplied with electric power. Specifically, a rotor (not shown) of the motor generator 12 is coupled to the crankshaft 11a of the engine 11. Therefore, a crank end torque is the sum of a torque output from the engine 11 (hereinafter, also referred to as an engine torque) and a torque output from the motor generator 12 (hereinafter, also referred to as a motor torque). The crank end torque is a torque at a shaft end of the crankshaft 11a of a power plant torque output from a power plant including the engine 11 and the motor generator 12. In the following description, a positive (plus) motor torque is also referred to as a power running torque, and a negative (minus) motor torque is also referred to as a regenerative torque.

Since the engine 11 and the motor generator 12 are mechanically coupled to each other, the vehicle 1 can perform motor assist in which driving of the drive wheel DW (that is, traveling of the vehicle 1) using the output of the engine 11 is assisted by an output of the motor generator 12.

Since the engine 11 and the motor generator 12 are mechanically coupled to each other, the motor generator 12 can be rotationally driven by the output of the engine 11, or the engine 11 can be rotationally driven by the output of the motor generator 12.

The motor generator 12 is electrically connected to the battery 20 via the power conversion device 21. The battery 20 is, for example, a battery that includes a plurality of electric power storage cells connected in series and can output a predetermined voltage (for example, 50 to 200 [V]). The electric power storage cells of the battery 20 may use a lithium ion battery, a nickel-metal hydride battery, or the like.

The power conversion device 21 is a device that includes an inverter (not shown), an AC-DC converter (not shown), and the like. The power conversion device 21 is controlled by the control device 30, and performs electric power conversion. For example, the power conversion device 21 converts DC electric power supplied from the battery 20 into three-phase AC electric power and supplies the three-phase AC electric power to the motor generator 12, or converts three-phase AC electric power supplied from the motor generator 12 into DC electric power and supplies the DC electric power to the battery 20. The motor generator 12 is supplied with electric power from the battery 20 via the electric power conversion device 21, so that the motor generator 12 can perform the motor assist described above.

The motor generator 12 also functions as a power generator that generates electric power by being rotationally driven. The motor generator 12 can be rotationally driven by the output of the engine 11 as described above, and can also be rotationally driven by power input from the drive wheel DW side accompanying with braking or the like of the vehicle 1. The electric power generated by the motor generator 12 is supplied to the battery 20 via the power conversion device 21, and is used to charge the battery 20.

The transmission TM is, for example, a multistage transmission having a plurality of shift stages (for example, seven shift stages), and is provided in a power transmission path from the engine 11 to the drive wheel DW. Specifically, the transmission TM includes a torque converter 13 and a gear box 14 as shown in FIG. 2.

The torque converter 13 includes a pump impeller 131, a turbine runner 132, a stator 133, and a lock-up clutch 134. The pump impeller 131 is mechanically coupled to the engine 11 and the motor generator 12 (specifically, the crankshaft 11a), and rotates integrally with the engine 11 and the motor generator 12 when the engine 11 and the motor generator 12 are rotationally driven. The turbine runner 132 has a hydraulic oil inlet located close to a hydraulic oil outlet of the pump impeller 131. The turbine runner 132 is mechanically coupled to an input shaft 141 of the gear box 14, and rotates integrally with the input shaft 141. The stator 133 is interposed between the turbine runner 132 and the pump impeller 131, and deflects a flow of hydraulic oil returning from the turbine runner 132 to the pump impeller 131. The stator 133 is supported by a housing (not shown) or the like of the torque converter 13 via a one-way clutch 135. The torque converter 13 can transmit power (rotation power) from the pump impeller 131 to the turbine runner 132 via the hydraulic oil by circulating the hydraulic oil in a circulation path formed between the pump impeller 131 and the turbine runner 132.

The lock-up clutch 134 is a clutch capable of mechanically connecting the engine 11 to and disconnecting the engine 11 from the input shaft 141 of the gearbox 14. An output of the engine 11 can be directly transmitted to the input shaft 141 of the gearbox 14 by bringing the lock-up clutch 134 into an engaged state. That is, while the lock-up clutch 134 is in the engaged state, the crankshaft 11a of the engine 11 and the input shaft 141 of the gear box 14 rotate integrally.

The gearbox 14 includes the input shaft 141 to which the output of the engine 11 or the motor generator 12 is transmitted via at least one of the torque converter 13 and the lock-up clutch 134, a plurality of transmission mechanisms 142 and 143 capable of shifting power transmitted to the input shaft 141, and an output member 144 including an output gear 144a that outputs the power shifted by any one of the plurality of transmission mechanisms to the drive wheel DW. The input shaft 141 is an example of a main shaft.

The plurality of transmission mechanisms provided in the gearbox 14 include a first transmission mechanism 142 and a second transmission mechanism 143. The first transmission mechanism 142 includes a first transmission clutch 142a, a first drive gear 142b that rotates integrally with the input shaft 141 while the first transmission clutch 142a is in an engaged state, and a first driven gear 142c that rotates integrally with the output member 144. The second transmission mechanism 143 includes a second transmission clutch 143a, a second drive gear 143b that rotates integrally with the input shaft 141 while the second transmission clutch 143a is in an engaged state, and a second driven gear 143c that rotates integrally with the output member 144.

Although FIG. 2 only shows the first transmission mechanism 142 and the second transmission mechanism 143 as the transmission mechanisms provided in the gear box 14, the gear box 14 also includes, for example, transmission mechanisms (not shown) other than the first transmission mechanism 142 and the second transmission mechanism 143.

Whether each clutch provided in the transmission TM such as the lock-up clutch 134, the first transmission clutch 142a, and the second transmission clutch 143a (hereinafter, also simply referred to as a clutch of the transmission TM) is brought into an engaged state or a disengaged state is controlled by the control device 30.

Returning to FIG. 1, the control device 30 is a device that controls the engine 11, the transmission TM, the power conversion device 21, and the like. Further, the control device 30 can also control the motor generator 12 via controlling the power conversion device 21. The control device 30 may directly control the motor generator 12, or may control an input and an output of the battery 20. The control device 30 is implemented by, for example, an electronic control unit (ECU) including a processor that executes various calculations, a storage device that stores various types of information, an input and output device that controls data input and output between an inner side and an outer side of the control device 30, and the like. The control device 30 may be implemented by a single ECU, or may be implemented by cooperation of a plurality of ECUs.

Various sensors are connected to the control device 30, and the control device 30 controls the engine 11, the transmission TM, the power conversion device 21 (that is, the motor generator 12), and the like based on information input from the various sensors. Examples of sensors connected to the control device 30 include an engine rotation speed sensor 17 that detects a rotation speed of the engine 11 (the crankshaft 11a) (hereinafter, also referred to as an engine rotation speed, see NE in FIG. 2), a vehicle speed sensor 18 that detects a traveling speed of the vehicle 1 (hereinafter, also referred to as a vehicle speed), and a main shaft rotation speed sensor 19 (see FIG. 2) that detects a rotation speed of the input shaft 141 (hereinafter, also referred to as a main shaft rotation speed, see NM in FIG. 2).

Further, examples of the sensors connected to the control device 30 include an AP sensor that detects an operation amount (hereinafter, referred to as an AP opening degree) on an accelerator pedal of the vehicle 1, a brake sensor that detects an operation amount on a brake pedal of the vehicle 1, a gear position sensor that detects a shift stage of the transmission TM, a battery sensor that detects an output or a temperature of the battery 20, and an intake pressure sensor that detects an intake pressure of the engine 11 (all of the sensors described above are not shown). In addition, an atmospheric pressure sensor (not shown) that detects an atmospheric pressure may be connected to the control device 30.

For example, the control device 30 derives a target torque for a crank end torque (hereinafter, also referred to as a crank end required torque) that is the sum of an engine torque and a motor torque, based on a traveling state of the vehicle 1. For example, the control device 30 derives the crank end required torque by referring to the vehicle speed detected by the vehicle speed sensor 18, the AP opening degree detected by the AP sensor, and a map that defines the crank end required torque required for traveling of the vehicle 1 in accordance with the vehicle speed and the AP opening degree. For example, the map is stored in advance in the storage device of the control device 30. The control device 30 controls the engine torque and the motor torque so that the crank end torque becomes the crank end required torque.

The control device 30 switches an operation state of the engine 11 between the all-cylinder operation and the deactivated-cylinder operation based on the crank end required torque. Specifically, the control device 30 controls the engine 11 in the deactivated-cylinder operation when the crank end required torque is relatively small, and controls the engine 11 in the all-cylinder operation when the crank end required torque becomes large to some extent. That is, the control device 30 improves fuel consumption performance of the vehicle 1 by operating the engine 11 in the deactivated-cylinder operation when the crank end required torque is small, and ensures an appropriate crank end torque according to a traveling state of the vehicle 1 by operating the engine 11 in the all-cylinder operation when the crank end required torque is large.

The control device 30 executes a fuel cut control for stopping fuel supply to the engine 11 in response to a deceleration request to the vehicle 1 that is traveling. The deceleration request is, for example, a brake on request for operating (for example, depressing) a brake pedal of the vehicle 1, an accelerator off request for releasing an operation on an accelerator pedal of the vehicle 1, or the like.

When the lock-up clutch 134 remains in the engaged state even after the vehicle 1 is brought into a low speed state due to the execution of the fuel cut control, power transmitted from the drive wheel DW to the engine 11 is reduced and an engine stall occurs, or vibration that may cause a driver to feel uncomfortable is generated. Therefore, the control device 30 can disengage the lock-up clutch 134 during the execution of the fuel cut control, and for example, the control device 30 disengages the lock-up clutch 134 when the vehicle speed reaches a predetermined speed (for example, 10 [km/h] or less) during the execution of the fuel cut control.

In a case where there is an acceleration request to the vehicle 1 when the fuel supply to the engine 11 is stopped by the fuel cut control, the control device 30 ends the fuel cut control and resumes the fuel supply to the engine 11. The acceleration request is, for example, a brake off request for releasing an operation on the brake pedal of the vehicle 1, an accelerator on request for operating the accelerator pedal, or the like.

In the vehicle 1, when the vehicle 1 is decelerated in response to a deceleration request, that is, when the control device 30 executes the fuel cut control, the motor generator 12 can generate electric power (generate regenerative electric power) by the power input from the drive wheel DW. At this time, an amount of electric power generated by the motor generator 12 (hereinafter, also simply referred to as an electric power generation amount) per unit time increases as a regenerative torque that is a torque input to the motor generator 12 increases, and the battery 20 can be charged in a short time.

As shown in FIGS. 1 and 2, when the engine 11 and the motor generator 12 are directly coupled to each other, it is conceivable to reduce the loss of the engine 11 relative to the power input from the drive wheel DW as a method of increasing the regenerative torque at the time of decelerating the vehicle 1. Therefore, the control device 30 opens a throttle valve (not shown, hereinafter, also simply referred to as a throttle) of the vehicle 1 at the time of decelerating the vehicle 1, that is, at the time of executing the fuel cut control. Accordingly, a pumping loss of the engine 11 at the time of decelerating the vehicle 1 can be reduced, and the regenerative torque can be increased.

Further, the control device 30 deactivates some cylinders of the engine 11 at the time of decelerating the vehicle 1 in the present embodiment. Specifically, the control device 30 fully closes intake and exhaust valves of three cylinders of one bank at the time of decelerating the vehicle 1. As a result, the pumping loss of the engine 11 at the time of decelerating the vehicle 1 can be further reduced, and the regenerative torque can be increased.

In a case where the throttle is opened during the execution of the fuel cut control, it is required to temporarily close the throttle to adjust an intake air amount of the engine 11 when the fuel supply to the engine 11 is resumed in response to the acceleration request. This is because, when the fuel supply to the engine 11 is resumed in a state in which the intake air amount is excessive (that is, in a state in which the intake pressure of the engine 11 is high), an excessive engine torque is output from the engine 11. As a result, the engine rotation speed overshoots, and the NV characteristics of the vehicle 1 deteriorate, or the vehicle 1 jumps out against the intention of a driver.

Therefore, in a case where the throttle is opened during the execution of the fuel cut control, a certain period of time is required for adjusting the intake air amount from a time when the acceleration request is issued to a time when the fuel supply to the engine 11 is resumed. When neither one of the above is performed during this period, the responsiveness of the vehicle 1 to the acceleration request is lowered.

Therefore, while the lock-up clutch 134 is disengaged and the throttle is opened accompanying with the execution of the fuel cut control, the control device 30 executes the motor assist in a case where there is an acceleration request to the vehicle 1. Specifically, the control device 30 executes the motor assist so as to compensate for the crank end required torque by the motor torque. The crank end required torque is increased in response to the acceleration request. Accordingly, it is possible to ensure an appropriate crank end torque in accordance with a traveling state of the vehicle 1, and it is possible to prevent a decrease in the responsiveness of the vehicle 1 to the acceleration request after the deceleration request.

When the motor assist is executed while the lock-up clutch 134 is disengaged accompanying with the execution of the fuel cut control, the engine rotation speed rapidly increases due to the co-rotation with the motor generator 12, whereas a rotation speed of the main shaft interlocked with the drive wheel DW may gently increase. As a result, the engine rotation speed lower than the main shaft rotation speed may become higher than the main shaft rotation speed. In this manner, when the engine rotation speed lower than the main shaft rotation speed becomes higher than the main shaft rotation speed, a transmission direction of power of the torque converter 13 is reversed. A torque fluctuation generated at the time of the reversing (hereinafter, also referred to as a reverse shock) increases when the engine rotation speed exceeds the main shaft rotation speed at once (that is, as a time during which the engine rotation speed and the main shaft rotation speed are the same rotation speed becomes shorter). Therefore, when the engine rotation speed exceeds the main shaft rotation speed at once, the NV characteristics of the vehicle 1 deteriorate.

Therefore, the control device 30 executes a motor torque reduction control for temporarily reducing an output from the motor generator 12 based on the engine rotation speed and the main shaft rotation speed during the execution of the motor assist. Specifically, when the control device 30 executes the motor torque reduction control, the control device 30 executes a control such that the motor torque (the power running torque) output from the motor generator 12 is smaller than that immediately before the execution of the motor torque reduction control.

The control device 30 executes the motor torque reduction control in such a manner, so that the control device 30 can temporarily increase the engine rotation speed in a gentle manner when the engine rotation speed becomes nearly equal to the main shaft rotation speed (for example, when a rotation speed difference between the engine rotation speed and the main shaft rotation speed falls within a predetermined range). Accordingly, it is possible to prevent the engine rotation speed from exceeding the main shaft rotation speed at once, it is possible to reduce the reverse shock when the engine rotation speed becomes higher than the main shaft rotation speed, and it is possible to prevent the deterioration of the NV characteristics of the vehicle 1.

In this manner, the control device 30 executes the motor assist in a case where there is an acceleration request while the lock-up clutch 134 is disengaged and the throttle of the vehicle 1 is opened accompanying with the execution of the fuel cut control, and executes the motor torque reduction control based on the engine rotation speed and the main shaft rotation speed during the execution of the motor assist, so that it possible to prevent the deterioration of the NV characteristics of the vehicle 1 while ensuring the responsiveness of the vehicle 1 to the acceleration request after the deceleration request. Hereinafter, an example of a specific control executed by the control device 30 will be described with reference to FIG. 3.

[Example of Specific Control Executed by Control Device]

FIG. 3 shows a relationship among times of (a) an execution state of the fuel cut control, (b) a state of the engine 11 (whether some cylinders are deactivated). (c) a state of the lock-up clutch 134, (d) an intake pressure of the engine 11, (e) various torques, (f) various rotation speeds, (g) a vehicle speed, and (h) an AP opening degree.

FIG. 3 shows an example of a case where there is an acceleration request when the vehicle 1 is decelerated in response to a deceleration request, and then the control device 30 accelerates the vehicle 1 in response to an acceleration request. In the example shown in FIG. 3, it is assumed that when the vehicle 1 is decelerated (that is, in a period up to a time t11 to be described later), the fuel cut control is executed by the control device 30, the lock-up clutch 134 is disengaged, and the throttle of the vehicle 1 is opened. In order to ensure a hydraulic pressure of oil supplied to the transmission TM or the like by a mechanical oil pump (not shown) coupled to the engine 11 (the crankshaft 11a), the control device 30 may cause the motor generator 12 to rotationally drive the engine 11 while the fuel cut control is executed so as to maintain the engine rotation speed at a predetermined speed.

At the time t11 shown in FIG. 3, it is assumed that a driver steps on the accelerator pedal and the AP opening degree is increased. When there is such an acceleration request, the control device 30 executes the motor assist so as to compensate for the crank end required torque by the motor torque. The crank end required torque is increased as the AP opening degree increases. As a result, the motor torque output from the motor generator 12 is increased. When there is an acceleration request, the control device 30 gradually closes the throttle in order to resume the fuel supply to the engine 11. As a result, the intake pressure of the engine 11 is reduced.

It is assumed that a rotation speed difference between the engine rotation speed and the main shaft rotation speed falls within a predetermined range at a time t12 after the time ti. In this case, the control device 30 starts the motor torque reduction control from the time t12 to reduce the motor torque (see a portion surrounded by a broken line denoted by a reference numeral 301 in FIG. 3).

For example, the control device 30 starts the motor torque reduction control when the engine rotation speed reaches the main shaft rotation speed−n1 [rpm] (n1≤0), and ends the motor torque reduction control when the engine rotation speed reaches the main shaft rotation speed+n2 [rpm] (n2≥0). That is, the control device 30 executes the motor torque reduction control at least when the engine rotation speed becomes higher than the main shaft rotation speed. Here, n1 and n2 are set in advance in the control device 30.

As described above, the control device 30 executes the motor torque reduction control in a case where the rotation speed difference between the engine rotation speed and the main shaft rotation speed falls within the predetermined range, and gently increases the engine rotation speed when the engine rotation speed becomes nearly equal to the main shaft rotation speed. For example, the control device 30 can increase the engine rotation speed along the main shaft rotation speed as indicated by a portion surrounded by a broken line denoted by a reference numeral 302 in FIG. 3. As a result, it is possible to prevent the engine rotation speed from exceeding the main shaft rotation speed at once, it is possible to reduce the reverse shock when the engine rotation speed becomes higher than the main shaft rotation speed, and it is possible to prevent the deterioration of the NV characteristics of the vehicle 1.

Then, at a time t13 after the time t12, when the intake pressure of the engine 11 reaches a predetermined startable negative pressure (that is, an appropriate intake air amount), the control device 30 ends the fuel cut control and resumes the fuel supply to the engine 11. As a result, it is possible to prevent the engine 11 from outputting an excessive engine torque when the fuel supply to the engine 11 is resumed and prevent the engine rotation speed from overshooting, and it is possible to start the engine 11 at an appropriate timing.

As shown in FIG. 3, it is desirable that the control device 30 brings the engine 11 into an all-cylinder operable state before resuming the fuel supply to the engine 11. As a result, it is possible to quickly increase the engine torque output from the engine 11 accompanying with the resuming of the fuel supply to the engine 11. The control device 30 can switch the engine 11 to the all-cylinder operable state while reducing a time for reducing a pressure to an appropriate intake pressure of the engine 11 by setting the engine 11 to the all-cylinder operable state in accordance with the closing of the throttle.

As shown in FIG. 3, the control device 30 executes the motor assist until the engine torque output from the engine 11 to which the fuel supply is resumed becomes the crank end required torque that is a target torque based on a traveling state of the vehicle 1. As a result, even when the engine 11 does not output a sufficient engine torque immediately after the fuel supply to the engine 11 is resumed, it is possible to ensure an appropriate crank end torque according to a traveling state of the vehicle 1 by the motor assist, and it is possible to prevent the occurrence of hesitation (so-called slowness of the vehicle 1) due to the lack of the crank end torque.

As shown in FIG. 3, when the engine torque output from the engine 11 increases as the fuel supply to the engine 11 is resumed, the control device 30 reduces the motor torque in accordance with the increase. The control device 30 engages the lock-up clutch 134 at a time 114 when the AP opening degree is constant after the fuel supply to the engine 11 is resumed. As a result, it is possible to reduce a shock that occurs when the lock-up clutch 134 is engaged, and it is possible to prevent the deterioration of the NV characteristics of the vehicle 1.

As described above, the control device 30 executes the motor assist in a case where there is an acceleration request while the lock-up clutch 134 is disengaged and the throttle is opened during the execution of the fuel cut control, and executes the motor torque reduction control w % ben the engine rotation speed becomes nearly equal to the main shaft rotation speed during the execution of the motor assist. As a result, it is possible to prevent the deterioration of the NV characteristics of the vehicle 1 while preventing a decrease in the responsiveness of the vehicle 1 to the acceleration request after the deceleration request.

Although the embodiment of the present disclosure has been described above, the present disclosure is not limited to the embodiment described above, and modifications, improvements, and the like can be made as appropriate.

For example, although an example has been described in the embodiment described above in which the power transmission device according to the present disclosure is the transmission TM that is a multistage transmission having a plurality of shift stages, the present disclosure is not limited thereto. The power transmission device may be a continuously variable transmission or may not include a transmission mechanism.

At least the following matters are described in the present specification. Although corresponding components or the like in the embodiment described above are shown in parentheses, the present disclosure is not limited thereto.

(1) A vehicle control device (the control device 30) for controlling a vehicle (the vehicle 1) that includes an internal combustion engine (the engine 11), an electric motor (the motor generator 12) coupled to the internal combustion engine, and a drive wheel (the drive wheel DW) coupled to the internal combustion engine and the electric motor via a power transmission device (the transmission TM) and that can execute a motor assist for assisting driving of the drive wheel by power of the electric motor, in which

the power transmission device includes a torque converter (the torque converter 13), a lock-up clutch (the lock-up clutch 134), and a main shaft (the input shaft 141) that can output, to the drive wheel, power of at least one of the internal combustion engine and the electric motor transmitted via at least one of the torque converter and the lock-up clutch,

the vehicle control device is configured to

execute a fuel cut control for stopping fuel supply to the internal combustion engine in response to a deceleration request to the vehicle:

disengage the lock-up clutch and open a throttle of the vehicle during the execution of the fuel cut control:

execute the motor assist in a case where there is an acceleration request to the vehicle while the lock-up clutch is disengaged and the throttle is opened; and

execute a motor torque reduction control for temporarily reducing an output of the electric motor based on a rotation speed of the internal combustion engine and a rotation speed of the main shaft during the execution of the motor assist.

According to (1), it is possible to prevent the deterioration of NV characteristics of the vehicle while ensuring responsiveness to the acceleration request after the deceleration request.

(2) The vehicle control device according to (1), in which

the motor torque reduction control is executed when a rotation speed difference between the rotation speed of the internal combustion engine and the rotation speed of the main shaft falls within a predetermined range.

According to (2), when the rotation speed of the internal combustion engine becomes nearly equal to the rotation speed of the main shaft, the vehicle control device can gently increase the rotation speed of the internal combustion engine, and the rotation speed of the internal combustion engine can be prevented from exceeding the rotation speed of the main shaft at once.

(3) The vehicle control device according to (0) or (2), in which

the vehicle control device is configured to close the throttle and end the fuel cut control when there is the acceleration request, and

the vehicle control device is configured to execute the motor assist until an output from the internal combustion engine to which the fuel supply is resumed reaches a target torque based on a traveling state of the vehicle.

According to (3), even when the output from the internal combustion engine is not sufficient immediately after the fuel supply is resumed, it is possible to ensure an appropriate drive force according to the traveling state of the vehicle by the motor assist, and it is possible to prevent the occurrence of hesitation due to the insufficient drive force.

(4) The vehicle control device according to (3), in which

the lock-up clutch is engaged after the fuel cut control is ended.

According to (4), it is possible to reduce a shock that occurs when the lock-up clutch is engaged, and it is possible to prevent the deterioration of the NV characteristics of the vehicle.

(5) The vehicle control device according to (3) or (4), in which

the fuel cut control is ended when an intake pressure of the internal combustion engine reaches a predetermined startable negative pressure after the throttle is closed.

According to (5), it is possible to prevent the internal combustion engine from outputting an excessive torque when the fuel supply to the internal combustion engine is resumed and prevent the rotation speed of the internal combustion engine from overshooting, and it is possible to start the internal combustion engine at an appropriate timing.

VEHICLE CONTROL DEVICE

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Priority Claims (1)