JP2012086802A - Control device of hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress uncomfortable feeling until a set vehicle speed is lowered during cruise traveling and the set vehicle speed is established.SOLUTION: When a driver operates a steering switch 28 in a state that an HEV mode is maintained, and then a coast operation is performed ("Yes" in the determination of S13), a coast flag is set to Fc=1 (S18), and a prohibition flag is set to F=1 (S19). Until a set vehicle speed Vs is established, cruise request torque Tc is inverted to a negative value and is made smaller than a stop determination threshold T, and an engine stop request is issued ("No" in the determination of S30), however, since the prohibition flag has been set to F=1 already ("NO" in the determination of S25), an engine 1 is maintained in an on-state (28).

Description

  The present invention relates to a control device for a hybrid vehicle.

  In a hybrid vehicle, when driving in the HEV mode in which the motor is appropriately driven while the engine is driven, if the driver releases the accelerator pedal, the engine is stopped to reduce fuel consumption and only the motor is driven. There was one that switched to the mode and traveled (see Patent Document 1).

JP 2005-160252 A

  By the way, the cruise control device is provided with a coast switch for reducing the set vehicle speed, and is configured to reduce the set vehicle speed according to, for example, the time during which the switch is pressed or the number of times the switch is pressed. Yes. As described above, when the coast switch is operated, the set vehicle speed is decreased, and the coast period during which the host vehicle is decelerated is set until the set vehicle speed is achieved.

Therefore, when the coast period is entered in the HEV mode, the engine is stopped to reduce the fuel consumption, thereby switching to the EV mode. The host vehicle is decelerated to the set vehicle speed and the engine is restarted when the coast period ends. It is possible.
In this way, if the engine is stopped and started within a short time from when the set vehicle speed is reduced during cruise traveling until the set vehicle speed is achieved, the driver may feel uncomfortable. There is.
An object of the present invention is to suppress a sense of incongruity when the set vehicle speed decreases during cruise traveling and the set vehicle speed is achieved.

  The control apparatus for a hybrid vehicle according to the present invention drives at least one of the engine and the motor according to a set vehicle speed that can be set by a driver's switch operation. When the set vehicle speed is reduced by the driver's switch operation at least while the wheels are driven by the engine, the engine is prohibited from being stopped until the set vehicle speed is achieved.

  According to the hybrid vehicle control device of the present invention, when the set vehicle speed decreases while the wheels are being driven by the engine, the engine stop is prohibited until the set vehicle speed is achieved. The engine will not stop and start in time. Therefore, it is possible to suppress a sense of incongruity when the set vehicle speed decreases during cruise traveling and the set vehicle speed is achieved.

1 is a schematic configuration diagram of a hybrid vehicle. It is a schematic block diagram of a control system. It is a figure which shows the main flow of the control command in a control system. It is a figure which shows the main functional blocks in a control system. It is a block diagram which shows a target drive torque calculating part. It is a flowchart which shows an engine start stop determination process. It is a time chart which shows the problem of a prior art. It is a time chart which shows operation | movement of this embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<< first embodiment >>
"Constitution"
FIG. 1 is a schematic configuration diagram of a hybrid vehicle.
Here, a rear-wheel drive hybrid vehicle is illustrated, but, of course, a front-wheel drive hybrid vehicle may be used.
First, the configuration of the power system (power train) will be described.
A motor generator (hereinafter simply referred to as a motor) 2 and an automatic transmission (transmission T / M) 3 are interposed in the middle of the torque transmission path from the engine 1 to the left and right rear wheels (drive wheels). A first clutch 4 is interposed between the engine 1 and the motor 3, and a second clutch 5 is interposed in the torque transmission path between the motor 3 and the drive wheel 7. Here, a configuration in which the second clutch 5 is incorporated in the automatic transmission 3 is illustrated. The automatic transmission 3 is connected to drive wheels 7 via a propeller shaft, a differential gear 6 and a drive shaft.

The engine 1 is a gasoline engine or a diesel engine. The engine 1 can control the valve opening degree of the throttle valve and the like based on a control command from an engine controller 22 described later. A flywheel may be provided on the output shaft of the engine 1.
The motor 2 is a synchronous motor in which a permanent magnet is embedded in a rotor and a stator coil is wound around a stator, for example. The motor 2 is controlled by applying a three-phase alternating current produced by an inverter 8 described later based on a control command from a motor controller 23 described later. The motor 2 can also operate as an electric motor that is driven to rotate by receiving power supplied from a battery 9 described later (this state is referred to as “powering”). Further, when the rotor is rotated by an external force, the motor 2 can function as a generator that generates electromotive force at both ends of the stator coil to charge the battery 9 (this operation state is “regeneration”). Called). The rotor of the motor 2 is connected to the input shaft of the automatic transmission 3 via a damper (not shown).

The first clutch 4 is a hydraulic single plate clutch interposed between the engine 1 and the motor 2. The first clutch 4 is engaged or disengaged by the control hydraulic pressure generated by the first clutch hydraulic unit so as to achieve the target clutch transmission torque based on a control command from the AT controller 24 described later. Note that both the engaged state and the released state include a slip state (half-clutch state).
The second clutch 5 is a hydraulic multi-plate clutch. The second clutch 5 is brought into an engaged state or a released state by a control hydraulic pressure generated by the second clutch hydraulic unit so as to obtain a target clutch transmission torque based on a control command from the AT controller 24 described later. Note that both the engaged state and the released state include a slip state (half-clutch state).

For example, the automatic transmission 3 can change the stepped gear ratio such as forward 7 speed / reverse 1 speed, forward 6 speed / reverse 1 speed, etc. to the vehicle speed or the shift accelerator opening degree input from the integrated controller 21 described later. It is a transmission that automatically switches in response. The second clutch 5 is not newly added as a dedicated clutch, and is configured by using several frictional engagement elements among a plurality of frictional engagement elements that are engaged at each gear stage of the automatic transmission 3. The
In the present embodiment, the case where the second clutch 5 is configured as a part of the automatic transmission 3 is illustrated, but the present invention is not limited to this. In addition, the second clutch 5 may be arranged between the motor 2 and the automatic transmission 3 or between the automatic transmission 3 and the differential gear.

  Each wheel includes a brake unit (not shown). Each brake unit includes, for example, a disc brake and a drum brake. Each brake unit may be a hydraulic brake device or an electric brake device. Each brake unit applies a braking force to the corresponding wheel in response to a command from the brake controller 25. Note that the brake unit need not be provided on all wheels.

  In FIG. 1, reference numeral 14 denotes an electric sub oil pump, and reference numeral 15 denotes a mechanical oil pump. These oil pumps 14 and 15 generate hydraulic pressure for each clutch. Reference numeral 10 denotes an engine rotation sensor that detects the rotation speed of the engine 1, and reference numeral 11 denotes a motor rotation sensor such as a resolver that detects rotation of the motor 2. Reference numeral 12 denotes an AT input rotation sensor that detects the rotation of the input shaft of the transmission, and reference numeral 13 denotes an AT output rotation sensor that detects the rotation of the output shaft of the transmission. Reference numeral 27 denotes a wheel speed sensor for detecting the rotation of the wheel. The wheel speed sensor 27 is also provided on the driven wheel (front wheel), and the vehicle speed V is calculated based on each wheel speed.

FIG. 2 is a schematic configuration diagram of the control system.
Reference numeral 33 denotes an accelerator pedal 33 operated by the driver. The accelerator opening APO of the accelerator pedal 33 is detected by the accelerator sensor 20, and the accelerator sensor 20 outputs the detected accelerator opening APO information to the integrated controller 21.
Reference numeral 34 denotes a pedal actuator 34. The pedal actuator 34 is an actuator that applies a pedal reaction force according to a command from the inter-vehicle controller 31 to the accelerator pedal 33.

Reference numeral 32 denotes a radar unit 32 constituting the preceding vehicle detection means. The radar unit 32 detects a preceding vehicle ahead of the vehicle and outputs the detected preceding vehicle information to the inter-vehicle distance controller 31.
Reference numeral 27 denotes a wheel speed sensor. The wheel speed sensor 27 outputs the detected wheel speed information to the brake controller 25. Further, the vehicle speed information obtained from the wheel speed information is output from the brake controller 25 to the integrated controller 21 and the inter-vehicle controller 31.

Reference numeral 35 is a meter for presenting the driving state to the driver. The meter 35 displays cruise control information and the like.
Reference numeral 29 denotes a brake switch 29. The brake switch 29 detects an operation of a brake pedal (not shown).
Reference numeral 28 denotes a steering switch. The steering switch 28 is an operation unit that is provided on the steering wheel unit and that is used by the driver to start cruise control and to change the driving conditions (such as the set vehicle speed). The cruise control of the present embodiment is a constant speed cruise control (ASCD: Auto Speed Control Device) that maintains the set vehicle speed, and an inter-vehicle distance cruise control (ACC: Adaptive Cruise Control) that automatically adjusts the set vehicle speed according to the inter-vehicle distance. Including both.

  The steering switch 28 has a set vehicle speed adjustment unit (not shown), and the set vehicle speed Vs is adjusted according to the switch operation of the set vehicle speed adjustment unit. For example, if the set vehicle speed adjusting unit is continuously pushed in a first direction (for example, upward), the set vehicle speed Vs can be increased according to the time, and if it is pushed briefly in the first direction (tap up), The set vehicle speed Vs can be increased by a fixed amount (for example, about 1.5 km / h). These operations in the first direction are collectively referred to as accelerator function operations. Further, if the set vehicle speed adjusting unit is continuously pushed in the second direction (for example, the downward direction), the set vehicle speed Vs can be decreased according to the time, and if it is pushed briefly in the second direction (tap down), a predetermined amount. The set vehicle speed Vs can be decreased by (for example, about 1.5 km / h). These operations in the second direction are collectively referred to as coast function operations.

Reference numeral 30 denotes a cruise cancel switch provided on the brake pedal. The cruise cancel switch 30 is an operator for instructing the end of cruise control. The steering switch 28 also has a switch for instructing the end of cruise control. This switch is also referred to as a cruise cancel switch 30.
Reference numeral 18 denotes a voltage sensor for detecting the voltage of the battery 9. Reference numeral 19 denotes a current sensor for detecting the current of the battery 9.

Next, the configuration of the control system will be described.
The hybrid vehicle control system includes an engine controller 22, a motor controller 23, an inverter 8, a battery controller 26, an AT controller 24, a brake controller 25, an integrated controller 21, and an inter-vehicle control controller 31. Yes.
Note that the engine controller 22, the motor controller 23, the AT controller 24, the brake controller 25, the inter-vehicle distance controller 31, and the integrated controller 21 exchange information by CAN communication.

  The engine speed information from the engine speed sensor 10 is input to the engine controller 22. Then, the engine controller 22 outputs a command for controlling the engine operating point (Ne, Te) to the throttle valve actuator, for example, according to the target engine torque from the integrated controller 21 and the like. Information about the engine speed Ne is acquired from the integrated controller 21 via CAN communication.

Information from the motor rotation sensor 11 that detects the rotor rotation position of the motor 2 is input to the motor controller 23. Then, the motor controller 23 outputs a command for controlling the motor operating point (Nm, Tm) of the motor 2 to the inverter 8 in accordance with the target motor torque, the rotational speed command, etc. from the integrated controller 21.
The battery controller 26 monitors the SOC indicating the state of charge of the battery 9. The battery controller 26 supplies the SOC information as control information of the motor 2 to the integrated controller 21 via CAN communication.

  The AT controller 24 receives wheel speed information and sensor information from the first and second clutch hydraulic pressure sensors. Then, the AT controller 24 performs the second clutch control in the shift control according to the accelerator opening APO state from the integrated controller 21, the first and second clutch control commands (target first clutch torque, target second clutch torque). A command for controlling the engagement / release of the second clutch 5 is output to the second clutch hydraulic unit in the AT hydraulic control valve, and a command for controlling the engagement / release of the first clutch 4 is given priority. Output to.

  The brake controller 25 receives sensor information from a wheel speed sensor 27 that detects the wheel speeds of the four wheels and a brake stroke sensor. The brake controller 25 calculates the target deceleration based on the stroke amount of the brake pedal, the braking request amount from the inter-vehicle controller 31 and the vehicle speed in a preset control cycle. Then, the brake controller 25 distributes the braking force to the cooperative regenerative braking request torque with the target deceleration as the rotational braking force and the target hydraulic braking force as the mechanical braking force (hydraulic braking force) as the regenerative cooperative brake control. . At this time, the cooperative regenerative braking request torque is output to the motor controller 23 via the integrated controller 21, and one target hydraulic braking force is output to the hydraulic braking force device. For example, when the required braking force obtained from the stroke amount of the brake pedal cannot be covered only by the regenerative braking force, the regenerative cooperative brake control is performed so that the shortage is compensated by the mechanical braking force.

  Information on the steering switch 28 set by the driver, cruise control operation permission state, and other necessary information are input to the inter-vehicle controller 31 via the integrated controller 21. If the inter-vehicle controller 31 determines that inter-vehicle distance control is required for the preceding vehicle based on the information from the integrated controller 21, the inter-vehicle controller 31 determines the preceding vehicle based on the own vehicle speed and the inter-vehicle distance and relative speed with the preceding vehicle. The target acceleration and target deceleration for calculating the target inter-vehicle distance and the target inter-vehicle time are calculated. The target acceleration is output to the integrated controller 21 as the inter-vehicle distance cruise request torque, and the target deceleration is output to the brake controller 25 as the braking request torque.

  The inter-vehicle controller 31 includes a DCA (Distance Control Assist) control unit 31A. The DCA control unit 31A calculates a pedal reaction force command based on accelerator opening APO information acquired from the integrated controller 21, vehicle speed information based on detection by the wheel speed sensor 27, and information from the radar unit 32. Then, the DCA control unit 31A outputs the calculated reaction force command to the pedal actuator 34 as support information for the driver to keep the distance from the preceding vehicle. The pedal actuator 34 applies a reaction force to the accelerator pedal 33.

The integrated controller 21 manages the energy consumption of the entire vehicle and has a function for running the vehicle with the highest efficiency.
The integrated controller 21 includes an engine speed sensor 10 that detects an engine speed Ne, a motor speed sensor 11 that detects a motor speed Nm, an AT input speed sensor 12 that detects a transmission input speed, and a transmission output speed. Various information is input from the AT output rotation sensor 13 for detecting the number. Furthermore, the accelerator opening 20 APO information is input from the accelerator sensor 20, and the storage state SOC information of the battery 9 is input from the battery controller 26 to the integrated controller 21. On the other hand, the integrated controller 21 also outputs various information via CAN communication.
The integrated controller 21 executes drive control of the engine 1 by a control command to the engine controller 22, executes drive control of the motor 2 by a control command to the motor controller 23, and executes the first clutch by a control command to the AT controller 24. 4 and the drive control of the second clutch 5 are executed.

Next, basic operations in the hybrid vehicle will be described.
If the battery SOC is low while the vehicle is stopped, the engine 1 is started to generate electric power, and the battery 9 is charged. When the battery SOC is in the normal range, the first clutch 4 is engaged, and the engine 1 is stopped while the second clutch 5 is disengaged.
At the time of start by the engine 1, the motor 2 is switched to power running operation or power generation operation according to the accelerator opening APO and the battery SOC state.
When the motor is running (EV mode), it is necessary to secure the cranking torque and the battery output necessary for starting the engine. Further, when the vehicle speed exceeds a predetermined vehicle speed based on a preset map or the like, the motor drive (EV mode) is shifted to the engine drive (HEV mode).

When the engine is running, the motor 2 assists the engine torque delay in order to improve the response when the accelerator is depressed. That is, while the engine is running, there are a case where the vehicle runs with only the driving force of the engine 1 and a case where the vehicle runs with both the driving force of the engine 1 and the driving force of the motor 2.
At the time of deceleration by the brake operation, a deceleration torque corresponding to the driver's brake operation is realized by regenerative cooperative brake control.
At the time of shifting during engine traveling or motor traveling, the motor 2 is switched to power generation operation or power running operation for smooth rotation without torque converter in order to adjust the rotational speed associated with shifting during acceleration / deceleration.

FIG. 3 is a diagram showing a main flow of control commands in the control system.
FIG. 4 is a diagram showing main functional blocks in the control system.
Next, main control processing executed by the integrated controller 21 will be described.
As shown in FIG. 4, the integrated controller 21 includes a required power generation torque calculation unit 21A, a required engine torque calculation unit 21B, a motor output possible torque calculation unit 21C, a target drive torque calculation unit 21D, and a vehicle state mode determination unit. 21E, an engine start control unit 21F, an engine stop control unit 21G, a target engine torque calculation unit 21H, a target motor torque calculation unit 21J, and a target clutch torque calculation unit 21K.

The required power generation torque calculator 21A calculates the required power generation torque to be generated by the motor 2 based on vehicle speed information, battery information such as SOC from the battery controller 26, and the like.
The required engine torque calculation unit 21B calculates the required engine torque to be generated in the engine 1 based on the accelerator opening APO, the vehicle speed V, the required power generation torque calculated by the required power generation torque calculation unit 21A, and the like.
The motor output possible torque calculation unit 21C calculates motor output possible torque that the motor 2 can output based on battery information such as SOC from the battery controller 26, vehicle speed V, and the like.
The target drive torque calculator 21D calculates the target drive torque.

FIG. 5 is a block diagram showing a target drive torque calculation unit.
The target drive torque calculator 21D includes an accelerator request torque calculator 21Da, a cruise request torque calculator 21Db, a basic target drive torque calculator 21Dc, a vehicle speed limiter torque calculator 21Dd, a final target drive torque calculator 21De, Is provided.
The accelerator request torque calculation unit 21Da calculates the accelerator request torque based on at least the accelerator opening APO information of the accelerator pedal 33 and the vehicle speed. In the example shown in FIG. 3, the accelerator required torque calculation unit 21Da inputs the accelerator opening APO and the transmission input rotation speed, and calculates the basic accelerator request torque with reference to the base torque map. Further, based on the vehicle speed V, the first correction torque is calculated with reference to the creep / coast driving force table. Further, the second correction torque is calculated with reference to the MG assist torque MAP based on the power limit information based on the accelerator opening APO information, the transmission input rotation speed, the SOC, and the like. Then, the accelerator request torque calculation unit 21Da calculates a final accelerator request torque based on the calculated basic accelerator request torque, the first correction torque, and the second correction torque.

The cruise request torque calculation unit 21Db outputs the steering switch 28 and the ACC permission signal to the inter-vehicle controller 31 and inputs the inter-vehicle control cruise request torque (ACC required torque) from the inter-vehicle controller 31. Further, the cruise request torque calculation unit 21Db calculates a constant speed cruise request torque for feedback control to the set vehicle speed Vs based on the set vehicle speed Vs set by the steering switch 28 and the current vehicle speed V _(n) . Then, according to ON / OFF of the inter-vehicle control, either one of the inter-vehicle control cruise request torque and the constant speed cruise request torque is selected and output as the final cruise request torque Tc. Specifically, if the inter-vehicle control is ON (ACC operation), the inter-vehicle control cruise request torque is prioritized, and the inter-vehicle control cruise request torque is selected as the final cruise request torque Tc instead of the constant speed cruise request torque. The

The basic target drive torque calculator 21Dc outputs the larger of the accelerator request torque calculated by the accelerator request torque calculator 21Da and the cruise request torque calculated by the cruise request torque calculator 21Db as the basic target drive torque ( Select high).
Speed limiter torque calculation unit 21Dd, based on the setting set by the steering switch 28 vehicle speed Vs and the current vehicle speed V _(n), calculates the vehicle speed limiter torque for more than the upper limit speed V _MAX.

The final target drive torque calculation unit 21De performs a select low between the basic target drive torque output by the basic target drive torque calculation unit 21Dc and the vehicle speed limiter torque calculated by the vehicle speed limiter torque calculation unit 21Dd. That is, the final target drive torque is obtained by limiting the basic target drive torque with the vehicle speed limiter torque.
On the other hand, the vehicle state mode determination unit 21E determines the vehicle state mode region map (EV−) based on the accelerator opening APO, vehicle speed information (or transmission output speed), motor output possible torque, required engine torque, and target drive torque. The target vehicle state mode (EV mode or HEV mode) is determined with reference to the HEV transition map).

For example, if the torque obtained by adding the cranking torque necessary for starting the engine 1 to the target drive torque is within a range that can be output by the motor 2, the target vehicle state mode is set to the EV mode. If there is a required power generation torque due to a request from the battery SOC or the like, the target vehicle state mode is set to the HEV mode.
If the current vehicle state mode is the EV mode and the target vehicle state mode is the HEV mode, the engine start sequence is processed. Conversely, when the current vehicle state mode is the HEV mode and the target vehicle state mode is the EV mode, the engine stop sequence is processed.

That is, when shifting from the HEV mode to the EV mode, an engine stop sequence process is executed, and this engine stop sequence process is a process until the engine stop is completed. Further, when shifting from the EV mode to the HEV mode, an engine start sequence process is executed, and this engine start sequence process is a process until the start of the engine is completed.
The vehicle state mode determination unit 21E executes an engine start / stop determination process, which will be described later, and determines engine start / stop.
When the engine start control unit 21F receives an engine ON command from the vehicle state mode determination unit 21E, the engine start control unit 21F starts the engine 1 to shift from the EV mode to the HEV mode, or drives the engine 1 to maintain the HEV mode. Maintain state.

Here, the engine start from the EV mode will be described.
The engine start control unit 21F first outputs the target second clutch torque command TCL2 to the AT controller 24 to control the second clutch 5 to the target clutch transmission torque. The target second clutch torque command TCL2 is a torque command capable of transmitting a torque equivalent to the output torque before the engine start process, and does not affect the output shaft torque even if the driving force output by the motor 2 is increased. And The AT controller 24 controls the second clutch hydraulic unit so that the clutch hydraulic pressure according to the command is generated.

The engine start control unit 21 then outputs a command for controlling the rotational speed of the motor 2 to the motor controller 23. The actual torque of the motor 2 is determined by the load acting on the motor 2.
Next, the engine start control unit 21 outputs the target first clutch torque command TCL1 to the AT controller 24, and controls the first clutch 4 to the target clutch transmission torque that becomes the engine cranking torque.

Next, the engine start control unit 21 detects that the engine speed and the motor speed are synchronized, and then outputs a command for completely engaging the first clutch 4 as the cranking process is completed. This synchronization determination is determined to be synchronized when a specified time elapses when the differential rotation between the actual motor rotation and the actual engine rotation is equal to or less than the specified value. This specified value is set to a differential rotation corresponding to the response dead time when shifting from the first clutch 4 to the fully engaged state. When it is detected that the engine speed is equal to or higher than the startable speed, an engine start command is output to the engine controller 22.
On the other hand, when the engine stop control unit 21G receives an engine OFF command from the vehicle state mode determination unit 21E, the engine stop control unit 21G stops the engine 1 in order to shift from the HEV mode to the EV mode, or maintains the EV mode. Maintain the stopped state. In addition, the engine stop in this embodiment refers to a fail cut.

Here, the engine stop from the HEV mode will be described.
The engine stop control unit 21G first outputs the target first clutch torque command TCL1 to the AT controller 24, and controls it to a predetermined target clutch transmission torque that makes the first clutch 4 slip.
Next, the engine stop control unit 21G outputs a command for controlling the rotation speed of the motor 2 to the motor controller 23 in synchronization. Thereby, while reducing the torque from the engine 1 by the first clutch 4, the motor torque is increased to obtain the target drive torque.

When the target motor torque reaches the target drive torque, the engine stop control unit 21G sets the target first clutch torque command TCL1 = 0, and then sets the target engine torque for the engine controller 22 to zero. As a result, the engine 1 is fuel cut (F / C), and the engine is idling.
On the other hand, the target engine torque calculation unit 21H is based on the target vehicle state mode determined by the vehicle state mode determination unit 21E, travel state information such as vehicle speed, target drive torque, and requested engine torque required for power generation. Calculate the torque. Note that when the target vehicle state mode is the EV mode, the engine torque is unnecessary, so the target engine torque is zero or a negative value. Further, when a preset fuel cut condition is satisfied, the engine is instructed to perform fuel cut and the engine is idling.

  The target motor torque calculation unit 21J calculates the target motor torque based on the target vehicle state mode determined by the vehicle state mode determination unit 21E, travel state information such as vehicle speed, target drive torque, and required power generation torque. For example, a value obtained by subtracting a torque value obtained by performing delay correction on the target engine torque from the target drive torque is set as the target motor torque. When the regenerative brake request torque (<0) is input from another control unit, a value obtained by adding the regenerative brake request torque to the target motor torque is set as the final target motor torque.

The target clutch torque calculation unit 21K calculates target clutch torque commands for the first clutch 4 and the second clutch 5 based on the target vehicle state mode determined by the vehicle state mode determination unit 21E and the torque generated by the engine 1 and the motor 2. . In the EV mode, the first clutch 4 is normally released by outputting a command for releasing the first clutch 4 to the AT controller 24 and outputting a command for engaging the second clutch 5 to the AT controller 24. At the same time, the second clutch 5 is engaged. Further, in the HEV mode state, the first clutch 4 is normally output to the AT controller 24 by outputting the engagement command of the first clutch 4 and outputting the engagement command of the second clutch 5 to the AT controller 24. The second clutch 5 is brought into an engaged state while being brought into an engaged state. In addition, when the engine is started or stopped, the target clutch torque command is calculated as described above.
Note that the VAPO calculation unit 21L in FIG. 3 calculates the corresponding estimated accelerator opening by back calculating from the cruise request torque, and outputs the calculated estimated accelerator opening to the AT controller 24 as the shift accelerator opening.

Next, an engine start / stop determination process executed at predetermined time intervals by the vehicle state mode determination unit 21E will be described.
FIG. 6 is a flowchart showing an engine start / stop determination process.
First, in step S11, it is determined whether or not the cruise control is set to ON. If the cruise control is set to ON, the process proceeds to step S13 described later. On the other hand, if the cruise control is set to OFF, the process proceeds to step S12.
In step S12, the prohibition flag is reset to F _NG = 0, and then the process proceeds to step S24 described later. The prohibition flag F _NG is a flag for prohibiting the engine stop. When F _NG = 0, the engine stop is not prohibited. When F _NG = 1, the engine stop is prohibited.

On the other hand, in step S13, it is determined whether or not a coasting operation has been performed by the driver. Here, if a coasting operation has been performed, the process proceeds to step S17 described later. On the other hand, if the coasting operation has been performed, the process proceeds to step S14.
In step S14, it is determined whether the coast flag is reset to Fc = 0. This coast flag is a flag indicating that it is during the coast period. When Fc = 0, it is not during the coast period, and when Fc = 1, it indicates that it is during the coast period. In the initial setting, Fc = 0 is reset. Here, if the determination result is “Fc = 1”, the process proceeds to step S20 described later. On the other hand, if the determination result is “Fc = 0”, the process proceeds to step S15.

In step S15, as shown below, the current vehicle state mode M _{(n) is set} to the pre-coast vehicle state mode Mf, and the memory is updated. The vehicle state mode includes an EV mode that travels only by a motor and an HEV mode that travels by appropriately driving a motor while driving an engine.
Mf ← M _(n)
In the subsequent step S16, the prohibition flag is reset to F _NG = 0, and then the process proceeds to step S24 described later.

On the other hand, in step S17, it is determined whether or not the pre-coast vehicle state mode Mf is set to the HEV mode. Here, if the determination result is “Mf: EV”, since the engine 1 is originally stopped, it is determined that the stop of the engine 1 is prohibited, and the process proceeds to step S12. On the other hand, if the determination result is “Mf: HEV”, it is determined that it is necessary to prohibit the stop of the engine 1 during the coast period, and the process proceeds to step S18.
In step S18, the coast flag is set to Fc = 1.
In the subsequent step S19, the prohibition flag is set to F _NG = 1.

In the following step S20, it is determined whether or not the current vehicle speed V _(n) is higher than the cruise control set vehicle speed Vs, that is, whether or not the set vehicle speed Vs has not been achieved. Here, if the determination result is “V _(n) > Vs”, it is determined that the coast period has not ended, and the process proceeds to step S24 described later while retaining the previous value of the prohibition flag _FNG . On the other hand, if the determination result is “V _(n) ≦ Vs”, it is determined that the coast period has ended, and the process proceeds to step S21.
In step S21, the storage of the pre-coast vehicle state mode Mf is reset.
In the subsequent step S22, the coast flag is reset to Fc = 0.

In the subsequent step S23, the prohibition flag is reset to F _NG = 0, and then the process proceeds to step S24.
In step S24, it is determined whether or not the cruise control is set to ON. Here, if the cruise control is set to ON, the process proceeds to step S29 described later. On the other hand, if the cruise control is set to OFF, the process proceeds to step S25.
In step S25, it is determined whether or not the prohibition flag is reset to F _NG = 0. Here, if the determination result is “F _NG = 1”, the engine stop is prohibited, and the process proceeds to step S28 described later. On the other hand, if the determination result is “F _NG = 0”, the engine stop is not prohibited, and the process proceeds to step S26.

In step S26, it is determined whether or not the engine start request is in a non-output state as shown in the following 1-3.
1. Engine start request based on accelerator opening Here, it is determined whether the accelerator opening APO is greater than a predetermined start determination threshold value, and when the accelerator opening APO is greater than the threshold value, the engine start request is in an output state. . The threshold value may be set according to the vehicle speed V.
2. Here, the engine start request is output when the SOC decreases, the water temperature decreases, or the EV traveling prohibition vehicle speed is reached.
3. Here, it is determined whether or not the cruise request torque Tc is greater than a predetermined start determination threshold value, and when the cruise request torque Tc is greater than the start determination threshold value, the engine start request is Become.

If there is an engine start request as shown in the above 1-3, the process proceeds to step S28 described later. On the other hand, if there is no engine start request as shown in the above 1-3, the process proceeds to step S27.
In step S27, an engine OFF command is output to the engine stop control unit 21G, and then the process returns to a predetermined main program.
On the other hand, in step S28, after an engine ON command is output to the engine start control unit 21F, the process returns to a predetermined main program.
On the other hand, in step S29, it is determined whether or not the engine 1 is in a driving state. If the engine 1 is in a stopped state, the process proceeds to step S31 described later. On the other hand, if the engine 1 is in a driving state, the process proceeds to step S30.

In step S30, it is determined whether or not the cruise request torque Tc is _{equal to} or greater than a predetermined stop determination threshold T _OFF . Here, if the determination result is “Tc <T _OFF ”, it is determined that it is a stop request for the engine 1, and the process proceeds to step S25. On the other hand, if the determination result is “Tc ≧ T _OFF ”, it is determined that there is no stop request for the engine 1, and the process proceeds to step S28.

On the other hand, in step S31, it is determined whether or not the cruise request torque Tc is equal to or greater than a predetermined start determination threshold value T _ON . The start determination threshold value T _ON is larger than the stop determination threshold value T _OFF described above, and the reason why hysteresis is provided between the start determination threshold value T _ON and the stop determination threshold value T _OFF is to prevent hunting. is there. Here, if the determination result is “Tc <T _ON ”, it is determined that there is no start request for the engine 1, and the process proceeds to step S25. On the other hand, if the determination result is “Tc ≧ T _ON ”, it is determined that the engine 1 is a start request, and the process proceeds to step S28.

<Action>
FIG. 7 is a time chart showing the problems of the prior art.
When the driver wants to decelerate and performs a coasting operation while cruising according to the cruise request torque Tc, the coasting period starts. The coast period is a period during which the host vehicle speed V is reduced, and is realized by reducing the driving force or applying a braking force. Since the vehicle speed is higher than the cruise request vehicle speed (for example, the set vehicle speed Vs) at the start of the coast period (target vehicle speed <actual vehicle speed), the cruise request torque Tc is set to a negative value in an attempt to quickly decelerate to the cruise vehicle speed. And turn.

  At this time, it is conceivable to switch to the EV mode by stopping the engine 1 to reduce fuel consumption, and to restart the engine 1 when the host vehicle decelerates to the set vehicle speed Vs and the coast period ends. As described above, when the engine 1 is stopped and started within a short time from when the set vehicle speed Vs is reduced during the cruise traveling until the set vehicle speed Vs is achieved, the driver feels uncomfortable. There is a possibility. In particular, the shock when restarting the engine 1 is not small.

FIG. 8 is a time chart showing the operation of the present embodiment.
Therefore, when the coast operation is performed by the driver and the set vehicle speed Vs is reduced at least while the engine 1 is being driven, the engine 1 is prohibited from being stopped until the set vehicle speed Vs is achieved.
Here, the above operation will be described in detail.
In the HEV mode, when the cruise request torque Tc is larger than the accelerator request torque Ta, the vehicle travels at the cruise request vehicle speed according to the cruise request torque Tc. At this time, if the constant speed cruise request torque is selected as the final cruise request torque Tc, the host vehicle speed is maintained at a substantially constant vehicle speed (set vehicle speed Vs). The vehicle state mode at this time is stored as the pre-acceleration vehicle state mode Mf (S15), and the prohibition flag is reset to F _NG = 0 (S16).

Then, if the driver operates the steering switch 28 and performs a coasting operation while maintaining the HEV mode (“Yes” in S13), the set vehicle speed Vs decreases, so that the set vehicle speed Vs is achieved. Thus, a coast period for decelerating the vehicle is started. The coast period is a period during which the host vehicle speed V is reduced, and is realized by reducing the driving force or applying a braking force. At this time, the coast flag is set to Fc = 1 (S18), and the prohibition flag is set to F _NG = 1 (S19).

At this time, since the vehicle speed is higher than the set vehicle speed Vs (target vehicle speed <actual vehicle speed), the cruise request torque Tc turns to a negative value in an attempt to quickly decelerate to the set vehicle speed Vs. Therefore, the cruise request torque Tc becomes smaller than the stop determination threshold T _OFF and becomes an engine stop request (determination in S30 is “No”), but the prohibition flag is set to F _NG = 1 (in S25) If the determination is “No”, the engine 1 is not stopped (S28). That is, since the engine 1 is maintained in the ON state, the vehicle is decelerated by the engine braking action. During this coast period, the prohibition flag holds F _NG = 1 (the determination in S20 is “Yes”), so the engine 1 also remains on (S28).

When the vehicle speed V decreases to the set vehicle speed Vs (determination in S20 is “No”), it is determined that the coast period has ended, the pre-coast vehicle state mode Mf is reset (S21), and the coast flag is set to Fc = 0. (S22), and the prohibition flag is reset to F _NG = 0 (S23).
Thus, since the engine 1 is maintained in the ON state even during the coast period, the engine 1 is already in the ON state even when the coast period ends. Thus, when the coast period ends, the engine 1 does not have to be restarted, so that the engine is not stopped and started in a short time. Accordingly, it is possible to suppress a sense of discomfort when the set vehicle speed Vs decreases during cruise traveling and the set vehicle speed Vs is achieved. In particular, it is possible to eliminate a shock when the engine 1 is restarted.

"effect"
From the above, the basic target drive torque calculation unit 21Dc, the engine controller 22, the motor controller 23, and the AT controller 24 correspond to “drive control means”.
(1) an engine capable of driving the wheel, a motor capable of driving the wheel, and a drive control means for driving at least one of the engine and the motor in accordance with a set vehicle speed that can be set by a driver's switch operation; And the drive control means prohibits the engine from being stopped until the set vehicle speed is achieved when the set vehicle speed is reduced by a driver's switch operation in a state where the wheel is driven by the engine at least. It is characterized by doing.
In this way, when the set vehicle speed is reduced while the wheels are being driven by the engine, the engine stop is prohibited until the set vehicle speed is achieved. There is no starting. Therefore, it is possible to suppress a sense of incongruity when the set vehicle speed decreases during cruise traveling and the set vehicle speed is achieved.

DESCRIPTION OF SYMBOLS 1 Engine 2 Motor 4 1st clutch 5 2nd clutch 7 Drive wheel 20 Accelerator sensor 21 Integrated controller 21A Requested power generation torque calculation part 21B Requested engine torque calculation part 21C Motor output possible torque calculation part 21D Target drive torque calculation part 21Da Acceleration request torque Calculation unit 21Db Cruise request torque calculation unit 21Dc First target drive torque calculation unit 21Dd Vehicle speed limiter torque calculation unit 21De Final target drive torque calculation unit 21E Vehicle state mode determination unit 21F Engine start control unit 21G Engine stop control unit 21H Target engine torque calculation Unit 21J target motor torque calculation unit 21K target clutch torque calculation unit 21L VAPO calculation 22 engine controller 23 motor controller 24 AT controller 25 brake controller 26 battery Controller 28 Steering switch 30 Cruise cancel switch 31 Distance control controller

Claims (1)

An engine capable of driving wheels,
A motor capable of driving wheels;
Drive control means for driving at least one of the engine and the motor according to a set vehicle speed that can be set by a driver's switch operation,
The drive control means includes
When the set vehicle speed is reduced by a driver's switch operation at least while the wheels are driven by the engine, the hybrid vehicle is prohibited from stopping the engine until the set vehicle speed is achieved. Control device.

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