JP2012086770A - Traveling control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the hunting of a stop and start of an engine accompanied by a variation of actual engine torque, in a hybrid vehicle.SOLUTION: When a target traveling state is not higher than a preset engine stop determination value, the drive of drive wheels by the engine is stopped. At this time, the engine stop determination value is corrected on the basis of deviation which is estimated between the target engine torque and the actual engine torque.

Description

  The present invention relates to a vehicular travel control technique for a hybrid vehicle that travels using an engine and a motor as drive sources and using at least one of the engine and motor according to the travel state.

  As a travel control device for a hybrid vehicle, for example, there is a technique described in Patent Document 1. The travel control apparatus of Patent Document 1 performs automatic constant speed travel control, gives a range to a target vehicle speed for fuel efficiency reduction, accelerates to the target upper limit value using the engine as a drive source, and sets a target upper limit value. Then, speed control that repeats a cycle of stopping the engine and performing coast regeneration (deceleration) until the target lower limit value is disclosed.

JP 2007-187090 A

In automatic constant speed (constant speed cruise) control, when engine start / stop determination is performed only by comparing the vehicle drive target drive torque with the engine stop determination value, the actual engine torque is larger than the target engine torque. If there is a problem, there is a possibility that the engine will be in a hunting state where engine start / stop is repeated. If the engine is started and stopped in a short time, the driver may feel uncomfortable due to the engine stop / start.
The present invention focuses on the above points, and an object of the present invention is to suppress engine stop / start hunting associated with actual engine torque fluctuations in a hybrid vehicle.

  In order to solve the above-described problem, the present invention stops the driving of the drive wheels by the engine when the target traveling state is equal to or less than a preset engine stop determination value. At this time, the engine stop determination value is corrected based on the estimated deviation between the target engine torque and the actual engine torque.

  According to the present invention, the engine stop determination value of the engine stop determination is decreased and corrected according to the difference between the target engine torque and the actual engine torque, thereby generating the engine stop / start hunting due to the actual engine torque fluctuation Can be reduced. This makes it possible to suppress a sense of discomfort given to the driver.

1 is a schematic configuration diagram of a hybrid vehicle according to an embodiment of the present invention. It is a figure which shows the structural example of the hybrid system which concerns on embodiment based on this invention. It is a figure which shows the flow of a basic signal in the integrated controller which concerns on embodiment based on this invention. It is a figure which shows the functional block of the integrated controller which concerns on embodiment based on this invention. It is a functional block of a target drive torque calculation part. It is a figure which shows the transition relationship of vehicle state mode. It is a functional block of a vehicle state mode determination part. It is a figure explaining the process of an engine starting determination process part. It is a figure explaining the process of an engine stop determination value calculating part. It is a figure which shows the relationship between an engine stop determination value and an engine start determination value. It is a figure which shows the relationship between a cruise request torque and an engine starting request | requirement. It is a figure explaining the case where this embodiment for a comparison is not applied. It is a figure explaining the case where this embodiment is applied. It is a figure which shows the example of a time chart which concerns on embodiment based on this invention. 10 is a diagram illustrating a time chart example of Modification 2. FIG. It is a figure explaining the stop determination value according to a vehicle speed.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a hybrid vehicle according to an embodiment. The hybrid vehicle shown in FIG. 1 is an example of rear wheel drive, but the present invention can also be applied to front wheel drive.
(Configuration of drive system)
First, the configuration of the drive system (power train) will be described.
As shown in FIG. 1, the power train of the present embodiment includes a motor 2 and an automatic transmission AT (= transmission T / M) in the middle of a torque transmission path from the engine 1 to the left and right rear wheels (drive wheels). Disguise. A first clutch 4 is interposed between the engine 1 and the motor 2. Further, the second clutch 5 is interposed in the torque transmission path between the motor 2 and the driving wheel (rear wheel). In this example, the second clutch 5 constitutes a part of the automatic transmission AT (= transmission T / M). The automatic transmission AT is connected to the drive wheel 7 (rear wheel) via a propeller shaft, a differential DF, 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 can be controlled by applying a three-phase alternating current generated 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 AT 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 a control hydraulic pressure generated by a first clutch hydraulic unit (not shown) so as to obtain an inputted target clutch transmission torque based on a control command from an AT controller 24 described later. It becomes an open state. The fastening / opening includes sliding fastening and sliding opening.

The second clutch 5 is a hydraulic multi-plate clutch. The second clutch 5 is engaged or disengaged by the control hydraulic pressure generated by the second clutch hydraulic unit so as to achieve the target clutch transmission torque based on a control command from the AT controller 24 described later. The fastening / opening includes sliding fastening and sliding opening.
The automatic transmission AT, for example, changes stepped gear ratios such as forward 7-speed reverse 1-speed and forward 6-speed reverse 1-speed according to the vehicle speed and the shift accelerator opening degree input from the integrated controller 21 described later. It is a transmission that switches automatically. Here, the second clutch 5 is not newly added as a dedicated clutch, and some of the frictional engagement elements that are engaged at each gear stage of the automatic transmission AT are used. And configure.

Here, although the case where the second clutch 5 is configured as a part of the automatic transmission AT (= transmission T / M) is illustrated in the present embodiment, the present invention is not limited to this. The second clutch 5 may be arranged between the motor 2 and the automatic transmission AT, or between the automatic transmission AT and the differential gear DF.
Each wheel is provided with 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 rotational speed of the engine 1, and reference numeral 11 denotes a motor rotation sensor such as a resolver that detects the rotation of the motor 2. Reference numeral 12 denotes an AT input rotation sensor that detects rotation of the input shaft of the transmission, and reference numeral 13 denotes an AT output rotation sensor that detects rotation of the output shaft of the transmission. Moreover, the code | symbol 27 shows the wheel speed sensor which detects rotation of a wheel. The wheel speed sensor 27 may also be provided on a driven wheel (front wheel) (not shown).

FIG. 2 is a configuration diagram illustrating the control system for the power train shown in FIG.
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 auto cruise 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 operator for a driver to start auto-cruise traveling, which is automatic traveling control, or to change a traveling condition (target vehicle speed, etc.). Here, the auto-cruise traveling of the present embodiment includes both constant speed traveling control (constant speed cruise) and inter-vehicle traveling control (inter-vehicle cruise).

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 the automatic cruise traveling that is automatic traveling control. The steering switch 28 also has a switch for instructing the end of the auto cruise. Hereinafter, this switch and the cruise cancel switch 30 are also referred to.
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 of the hybrid vehicle will be described.
As shown in FIG. 2, 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, and an integrated controller 21. Have. Further, the control system of the hybrid vehicle of this embodiment includes an inter-vehicle distance controller 31.

Note that the engine controller 22, the motor controller 23, the AT controller 24, the AT controller 24, the brake controller 25, the inter-vehicle control controller 31, and the integrated controller 21 are CAN communication lines (not compatible) that can exchange information with each other. Connected through the figure.
The engine controller 22 inputs engine speed information from the engine speed sensor 10. Then, the engine controller 22 outputs a command for controlling the engine operating point (Ne, Te) according to the target engine torque or the like from the integrated controller 21, for example, to a throttle valve actuator (not shown). Information about the engine speed Ne is acquired from the integrated controller 21 via the CAN communication line.

The motor controller 23 inputs information from the motor rotation sensor 11 that detects the rotor rotation position of the motor 2. 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 battery SOC that represents the state of charge of the battery 9. The battery controller 26 supplies battery SOC information to the integrated controller 21 via the CAN communication line as control information of the motor 2 or the like.

  The AT controller 24 inputs vehicle 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 information from the integrated controller 21 and the first and second clutch control commands (target first clutch torque, target second clutch torque). Is output to the second clutch hydraulic unit in the AT hydraulic control valve, and the command for controlling the engagement / release of the first clutch 4 is output to the first clutch hydraulic pressure. Output to a unit (not shown).

  The brake controller 25 inputs sensor information from a wheel speed sensor 27 for detecting each wheel speed of the four wheels and a brake stroke sensor. The brake controller 25 calculates a 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. Then, the cooperative regenerative brake request torque is output to the motor controller 23 of the integrated controller 21. The target hydraulic braking force is output to the hydraulic braking force device. For example, the brake controller 25 performs regenerative cooperative brake control when the regenerative braking force is insufficient with respect to the required braking force obtained from the brake stroke BS or the like at the time of brake depression. Then, regenerative cooperative brake control is performed based on the regenerative cooperative control command from the integrated controller 21 so that the shortage is compensated by mechanical braking force (hydraulic braking force or motor 2 braking force).

  Further, the inter-vehicle controller 31 receives information on the steering switch 28 set by the driver, cruise control operation permission state, and other necessary information from the integrated controller 21. When the inter-vehicle controller 31 determines that the inter-vehicle control is to be performed on the preceding vehicle based on the information from the integrated controller 21, the preceding vehicle information (the inter-vehicle distance, the relative speed, etc.) based on the own vehicle speed and the detection of the radar unit 32. Based on the above, a target acceleration and a target deceleration for calculating the target inter-vehicle distance and the target inter-vehicle time with respect to the preceding vehicle are calculated. Then, the inter-vehicle controller 31 outputs the obtained target acceleration to the integrated controller 21 as inter-vehicle cruise request torque (ACC required torque). Further, the inter-vehicle controller 31 outputs the obtained target deceleration to the brake controller 25 as a braking request torque.

  The inter-vehicle distance controller 31 includes a DCA control (Distance Control Assist) unit 31A. The DCA control unit 31A calculates a pedal reaction force command based on accelerator opening APO information received 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 input accelerator pedal 33.

The integrated controller 21 is responsible for managing the energy consumption of the entire vehicle and 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. Information from the AT output rotation sensor 13 is detected. Further, the integrated controller 21 inputs accelerator opening APO information from the accelerator sensor 20 and information on the storage state SOC of the battery 9 from the battery controller 26. Further, the integrated controller 21 outputs information acquired via the CAN communication line.

  Further, the integrated controller 21 performs operation control of the engine 1 in accordance with a control command to the engine controller 22. The integrated controller 21 executes operation control of the motor 2 according to a control command to the motor controller 23. The integrated controller 21 executes engagement / release control of the first clutch 4 according to a control command to the AT controller 24. The integrated controller 21 executes the engagement / release control of the second clutch 5 according to a control command to the AT controller 24.

Here, the basic operation mode in the hybrid vehicle of the present embodiment 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 second clutch 5 is released, and the engine 1 is stopped.
At the time of starting by the engine 1, the motor 2 is rotated according to the accelerator opening APO and the battery SOC state to switch to power running / power generation.

Motor running (EV mode) secures the motor torque and battery output necessary for starting the engine, and shifts to engine running if insufficient. Further, when the vehicle speed exceeds a predetermined vehicle speed set in advance based on a preset map or the like, the motor drive (EV mode) is shifted to the engine drive (HEV mode). In addition, 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 is a mode in which the vehicle runs with only the power of the engine 1 or with both the power of the engine 1 and the motor 2.
At the time of brake-on deceleration, a deceleration force corresponding to the driver's brake operation is obtained by regenerative cooperative brake control.
At the time of shifting during engine traveling or motor traveling, the motor 2 is regenerated / powered for smooth rotation without torque converter in order to adjust the rotational speed associated with shifting during acceleration / deceleration.

FIG. 3 illustrates a schematic configuration diagram illustrating a basic flow of basic command values in the control of the integrated controller 21 of the present embodiment. FIG. 4 is a functional block diagram functionally illustrating the control of the integrated controller 21 of the present embodiment.
Next, a part related to the present invention in the braking / driving control process 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, a vehicle state mode determination unit 21E, an engine start A control unit 21F, an engine stop control unit 21G, a target engine torque calculation unit 21H, a target motor torque calculation unit 21J, a target clutch torque calculation unit 21K, and an engine stop determination value calculation unit 21M are provided.

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 that should be generated in the engine 1 based on the running state such as the vehicle speed, 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, and the like.

  The target drive torque calculation unit 21D calculates a target drive torque to be targeted. The target drive torque calculator 21D includes a driver request torque calculator and an automatic control request torque calculator. The driver request torque calculation unit calculates the driver request torque that is estimated to be requested by the driver based on the operation amount (accelerator opening APO) of the accelerator pedal 33 operated by the driver. In addition, the automatic control request torque calculation unit is operated by operating a steering switch that is an automatic travel control switch, and is kept in a traveling state of a traveling condition (set vehicle speed) preset by the driver until the operation is terminated by the operation of the cruise cancel switch 30. Calculate the required torque for automatic control for automatic adjustment. Then, the target drive torque calculator 21D calculates the target drive torque based on the driver request torque calculated by the driver request torque calculator and the automatic control request torque calculated by the automatic control request torque calculator.

As shown in FIG. 5, the target drive torque calculation unit 21D of the present embodiment includes a driver request torque calculation unit 21Da, an automatic control request torque calculation unit 21Db, a first target drive torque calculation unit 21Dc, a vehicle speed limiter torque calculation unit 21Dd, The final target drive torque calculation unit 21De is provided.
The driver request torque calculation unit 21Da calculates the driver 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 driver request torque calculation unit 21Da inputs the accelerator opening APO and the transmission input rotation speed, and calculates the basic driver request torque with reference to the base torque map. Further, the first correction torque is calculated based on the vehicle speed with reference to the creep / coast drive torque 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 driver request torque calculation unit 21Da calculates a final driver request torque based on the calculated basic driver request torque, the first correction torque, and the second correction torque.

  The automatic control request torque calculation unit 21Db outputs the steering switch 28 and the ACC permission signal to the inter-vehicle control controller 31 and inputs the inter-vehicle cruise request torque (ACC required torque) from the inter-vehicle control controller 31. Further, the automatic control request torque calculation unit 21Db calculates a cruise request torque for feedback control to the set vehicle speed based on the set vehicle speed set by the steering ring SW and the current vehicle speed. The automatic control request torque selects either the inter-vehicle cruise request torque (ACC request torque) or the cruise request torque as the automatic control request torque according to the presence or absence of the ACC operation (the inter-vehicle control operation). Here, during the ACC operation, processing is performed so that the inter-vehicle cruise request torque is selected with priority over the cruise request torque.

The first target drive torque calculation unit 21Dc performs a select high of the driver request torque calculated by the driver request torque calculation unit 21Da and the automatic control request torque calculated by the automatic control request torque calculation unit 21Db. One target drive torque is selected and output.
The vehicle speed limiter torque calculating unit 21Dd calculates a vehicle speed limiter torque for setting the vehicle speed to be equal to or lower than the upper limit vehicle speed based on the set vehicle speed set by the steering switch 28 and the current vehicle speed.
The final target drive torque calculation unit 21De performs a select low between the first target drive torque output by the first 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 target drive torque is obtained by limiting the first target drive torque with the vehicle speed limiter torque.

  The vehicle state mode determination unit 21E determines a vehicle state mode region map (EV-HEV transition) based on the accelerator opening APO, vehicle speed information (or transmission output speed), motor output possible torque, required engine torque, and target drive torque. A target vehicle state mode (EV mode, HEV mode) as a target is determined with reference to a map). For example, when the torque obtained by adding the cranking torque necessary for starting the engine 1 to the target drive torque for vehicle braking / driving control falls below the torque that the motor 2 can output, the operation mode is changed from the HEV mode to the EV mode. Transition. Further, when there is a required engine torque due to a system request such as a battery charge request, the target vehicle state mode to be targeted 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. Further, 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.

  Here, as shown in FIG. 6, the vehicle state mode includes an HEV mode, an EV mode, and an engine stop sequence mode and an engine start sequence mode which are modes at the time of transition. The HEV mode is a vehicle state mode in which the vehicle travels with at least the engine 1 as a drive source. The mode of the engine stop sequence is a vehicle state mode at the time of transition when shifting from the HEV mode to the EV mode. The engine start sequence mode is a vehicle state mode at the time of transition from the EV mode to the HEV mode. When the current vehicle state mode and the target vehicle state mode are the same, the previous state mode is maintained. For example, when the current vehicle state mode is the EV mode and the target vehicle state mode is also the EV mode, the vehicle state mode is set to the EV mode. When the current vehicle state mode is the HEV mode and the target vehicle state mode is also the HEV mode, the vehicle state mode is set to the HEV mode. On the other hand, when the current vehicle state mode is the EV mode and the target vehicle state mode is the HEV mode, or when the current vehicle state mode is the HEV mode and the target vehicle state mode is the EV mode, the transition mode of the engine 1 Until the stop or start process is completed, the engine stop sequence mode or the engine start sequence mode is entered.

As shown in FIG. 7, the vehicle state mode determination unit 21E in the present embodiment includes an engine start / stop determination processing unit 21Ea and a mode transition processing unit 21Eb.
The processing of the engine start / stop determination processing unit 21Ea will be described with reference to the flowchart of FIG.
First, in step S10, it is determined whether or not the target drive torque (cruise request torque) is equal to or greater than a preset engine start determination value. If it is equal to or greater than the engine start determination value, the process proceeds to step S30. If it is less than the engine start determination value, the process proceeds to step S20.

In step S20, it is determined whether or not the target drive torque (cruise request torque) is less than a preset engine stop determination value. If it is less than the engine stop determination value, the process proceeds to step S40. If it is greater than or equal to the engine stop determination value, the process proceeds to step S50. Here, the engine stop determination value is set by the engine stop determination value calculation unit 21M.
In step S30, the torque request engine start request is set to “ON”, and the process proceeds to step S100.

In step S40, the torque request engine start request is set to “OFF”, and the process proceeds to step S100.
In step S50, the previous value is held as the torque request engine start request, and the process proceeds to step S100.
In step S100, it is determined whether or not auto-cruise is being controlled. When the cruise control is being performed, the process proceeds to step S110. If the cruise control is not being performed, the process proceeds to step S140.

In step S110, it is determined whether the cruise request torque (target drive torque) is equal to or greater than a preset start determination torque. If it is equal to or greater than the start determination torque, the process proceeds to step S120. If the cruise request torque (target drive torque) is less than the start determination torque, the process proceeds to step S130.
In step S120, the cruise engine start request is turned ON, and the process proceeds to step S200.
In step S130, the cruise engine start request is turned OFF and the process proceeds to step S200.
In step S140, the cruise engine start request is turned OFF and the process proceeds to step S200.

In step S200, when any of the following conditions is satisfied, the process proceeds to step S210. On the other hand, if the condition is not satisfied, the process proceeds to step S220.
(1) Satisfy the start request by the accelerator opening APO (2) Determine whether the start request by the system is satisfied.
(3) Cruise engine start request is ON
The start request by the accelerator opening APO is satisfied when the current accelerator opening APO is equal to or greater than the preset start accelerator opening. The starting accelerator opening APO may be changed according to the vehicle speed.

The start request by the system satisfies other engine start requests in a situation where the engine 1 needs to be driven by a system such as a decrease in SOC, a decrease in water temperature, or an EV prohibited vehicle speed.
The cruise engine start request is ON when the cruise engine start request is ON.
In step S210, the engine start request is turned ON and the process proceeds to step S250. Then return.
In step S220, the engine start request is turned OFF and the process proceeds to step S250. Then return.

  Further, the mode transition processing unit 21Eb performs a mode transition process in response to the engine start request obtained by the engine start / stop determination processing unit 21Ea. That is, when the engine start request is ON, if the current vehicle state mode is not the HEV mode, the engine start flag is turned ON and processing for operating the engine start control unit 21F is executed. When the engine start request is OFF, if not in the EV mode, the engine stop flag is turned ON, and processing for operating the engine stop control unit 21G is executed.

Next, the process of the engine stop determination value calculation unit 21M will be described with reference to FIG.
First, in step S300, the engine stop determination value calculation unit 21M determines whether or not it is in the HEV mode, that is, whether or not the target engine torque is being calculated. If the condition is satisfied, the process proceeds to step S310. On the other hand, if the condition is not satisfied, the process proceeds to step S310.
In step S310, the actual engine torque estimated by the engine controller 22 is input from the engine controller 22. The actual engine torque may be calculated by a known method from parameters such as the intake air amount and the fuel injection amount that are parameters for controlling the engine 1.

Then, for the target engine torque and the estimated actual engine torque, torque lower limit processing is performed with the combustion lower limit torque as in the following equation. Thereafter, the process proceeds to step S320.
Target engine torque = MAX (target engine torque, lower combustion limit torque)
Actual engine torque = MAX (actual engine torque, lower combustion limit torque)
Here, the combustion lower limit torque is a lower limit value of torque that can be output by the engine, obtained from the current engine speed. The combustion lower limit torque is, for example, about several N. However, the combustion lower limit torque is not the engine friction when the fuel is cut (F / C) but the torque at the time of fuel injection, that is, the idling equivalent torque.

In step S320, a deviation is calculated based on the following equation. Thereafter, the process proceeds to step S330. Here, as can be seen from the following equation, the deviation takes a positive value when the actual engine torque is larger than the target engine torque.
Deviation = actual engine torque-target engine torque In step S320, a final engine torque deviation is calculated based on the following equation. That is, when the actual engine torque is larger than the target engine torque, a decrease correction is performed.
Engine torque deviation = MAX (deviation, 0)

In step S330, a correction amount corresponding to the engine torque deviation is obtained. That is, as shown in the following equation, the engine torque deviation is multiplied by a preset F / B gain, and converted to a torque amount as a proportional term of feedback control. Thereafter, the process proceeds to step S350.
F / B correction term = engine torque deviation × F / B gain In step S340, the F / B correction term is cleared to zero and the process proceeds to step S350.

In step S350, an engine stop determination value-based value is calculated.
The engine stop determination value base is an engine stop determination value before correction is made by the F / B correction term. The engine stop determination value base is calculated using a preset map. The engine stop determination value base of the present embodiment is a value set in a table for each vehicle speed. For example, the value based on the engine stop determination value is set to a smaller value as the running resistance estimated by the vehicle speed is larger. That is, the engine stop determination value base value is set to a smaller value as the vehicle speed increases.

That is, as shown in FIG. 16A, the running resistance increases as the vehicle speed increases. Therefore, for example, the stop determination margin torque is calculated based on the vehicle speed using a relationship map, function, or the like as shown in FIG. Then, as shown in FIG. 16C, the engine stop determination value base is calculated by subtracting the stop determination margin torque from a preset start determination value.
Here, the reason why the engine stop determination value base is switched at the vehicle speed is that the running resistance changes depending on the vehicle speed.
In step S360, the engine stop determination value base is subtracted and corrected by the F / B correction term to calculate the engine stop determination value as in the following equation.
Engine stop judgment value = Engine stop judgment value base-F / B correction term

Here, the engine stop determination value is set to a value smaller than the engine start determination value as shown in FIG.
The target engine torque calculation unit 21H calculates the target engine 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 requested engine torque required for power generation. calculate. 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. When the preset F / C condition is satisfied, fuel cut (F / C) is instructed to the engine, 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 engine start control unit 21F operates when the engine start flag is ON, performs a process of starting the engine 1 while the motor is running, and performs a transition process to the HEV mode.

Next, a processing example of the engine start control unit 21F will be described.
The engine start control unit 21F is activated when an engine start command (engine start flag is ON) is acquired during motor running.
First, a target second clutch torque command for setting the second clutch 5 to the target clutch transmission torque is output to the AT controller 24. The target second clutch transmission torque command TCL2 is a transmission torque command capable of transmitting a torque equivalent to the output torque before the engine starting process, and does not affect the output shaft torque even if the drive torque output by the motor 2 is increased. The range is not given. Here, the AT controller 24 controls the second clutch hydraulic unit so that the clutch hydraulic pressure according to the command is generated.

  Next, a command for controlling the rotational speed of the motor 2 is output to the motor controller 23. The actual torque of the motor 2 is determined by the load acting on the motor 2. Subsequently, a torque command is output to the AT controller 24 so that the torque transmission torque of the first clutch 4 becomes the torque for engine cranking. Subsequently, when it is detected that the engine rotation speed and the motor rotation speed are synchronized, a command for completely engaging the first clutch 4 is output as the end of the cranking process. The synchronization determination of the first clutch 4 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 a specified value. The specified value sets a differential rotation corresponding to a response dead time when shifting from the first clutch 4 torque control to complete engagement. Further, 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. Then return.

The engine stop control unit 21G is activated when an engine stop command (engine stop flag is ON) is acquired, and performs a transition process from the HEV mode to the EV mode.
For example, the engine stop control unit 21G is activated upon obtaining an engine stop command (engine stop flag is ON), and first outputs a preset torque command for slidingly engaging the first clutch 4 to the AT controller 24. To do. Synchronously, a command for controlling the rotational speed of the motor 2 is output to the motor controller 23. 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 becomes the target drive torque, a target first clutch 4 torque command for setting the first clutch 4 to target clutch transmission torque = 0 is output to the AT controller 24. Thereafter, the target engine torque is set to zero and output to the engine controller 22. As a result, the engine is fuel cut (F / C), and the engine is idling.

The target clutch torque calculation unit 21K calculates target clutch torques of 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 state, the first clutch 4 is normally set in the released state by outputting a release command for the first clutch 4 and an engagement command for the second clutch 5 to the AT controller 24. At the same time, the second clutch 5 is engaged. In the HEV mode state, the first clutch 4 is normally set to the engaged state by outputting the engagement command for the first clutch 4 and the engagement command for the second clutch 5 to the AT controller 24. At the same time, the second clutch 5 is engaged. In addition, in the case of engine start or stop processing, the clutch torque that results in the above-described engagement / release state is calculated.
Note that the VAPO calculation 21L in FIG. 3 calculates the corresponding estimated accelerator opening from the cruise request torque, and outputs the calculated estimated accelerator opening to the AT controller 24 as the shift accelerator opening.

(Function)
When the automatic cruise traveling, which is the automatic traveling, is not being controlled, the output of at least one of the engine 1 and the motor 2 as the driving source is controlled using the driver requested torque based on the accelerator opening APO as the target driving torque. Then, for example, when the engine start condition is satisfied, for example, the accelerator is depressed and the vehicle exceeds a predetermined vehicle speed, the engine 1 is started to enter the HEV mode, and for example, the accelerator is stepped back. When the engine stop condition is satisfied, the engine 1 is stopped and shifts to the EV mode.

  On the other hand, when the steering switch 28 is operated and the control of the auto cruise traveling is started, the automatic control request torque for setting the vehicle speed set by the driver is calculated as the target drive torque and becomes the target drive torque. As described above, the output of at least one of the engine 1 and the motor 2 that are drive sources is controlled. In this case, when the driver does not make a temporary acceleration request, the accelerator pedal 33 is in an OFF state. Only when it is desired to accelerate temporarily, the driver depresses the accelerator pedal 33, so that the vehicle is temporarily accelerated.

Here, it is assumed that the vehicle is traveling on an automatic cruise that is in an automatic traveling state.
In this case, when the target drive torque (automatic control request torque) exceeds the engine start determination value, the mode shifts to HEV mode. Conversely, when the target drive torque (automatic control request torque) becomes less than the engine stop determination value, the EV mode is set. Transition. At this time, as shown in FIG. 10, by making the engine start determination value larger than the engine stop determination value, a dead zone is provided to make hunting difficult.

For example, as shown in FIG. 11, when the automatic control request torque (cruise request torque) is equal to or higher than the engine start determination value, the engine start request is turned on to enter the engine start mode, and then the automatic control request torque (cruise request) When the request torque is less than the engine stop determination value, the engine start request is turned OFF and the engine stop process is performed.
Here, it is assumed that the constant speed cruise is controlled in the HEV mode so as to achieve the target vehicle speed. FIG. 12 shows an example when the present invention is not applied, and FIG. 13 shows an example when the present invention is applied.

At this time, the cruise request torque (target drive torque) is a value for the running resistance. Assume that the engine output is controlled using the cruise request torque as the target engine torque. In this case, if the target engine torque becomes smaller than the actual engine torque due to fluctuations in engine torque due to air density or the like, the target drive torque is smaller than the actual drive torque as shown in FIG.
Then, in order to lower the actual vehicle speed to the target vehicle speed, the cruise demand torque is lowered by the automatic braking demand torque calculation unit.
At this time, if the cruise request torque (target drive torque) decreases and the cruise request torque becomes less than the engine stop determination value, the engine stop process is performed and the EV mode is entered.

  Then, the cruise demand torque can be realized only by the motor torque, but the vehicle speed is lowered because the torque for the running resistance that is originally required for steady running is insufficient. Then, the automatic braking request torque calculation unit increases the cruise request torque in an attempt to increase the actual vehicle speed to the target vehicle speed, and when the cruise request torque exceeds the engine start determination value, the engine starts again and shifts to the HEV mode. .

When the target engine torque becomes smaller than the actual engine torque again, the vehicle is accelerated as described above, and the above state is repeated. FIG. 12 shows this state.
On the other hand, in the present embodiment, the target engine torque becomes smaller than the actual engine torque, and the vehicle is accelerated, so that the cruise request torque (target drive torque) is reduced by the automatic braking request torque calculation unit. At this time, as shown in FIG. 13, the engine stop determination value is corrected to decrease by an amount corresponding to the deviation between the target engine torque and the actual engine torque.

For this reason, even if the cruise request torque (target drive torque) decreases, the engine stop determination value is also corrected to decrease, so that the engine start request is more easily maintained ON than in the above-described case. As a result, the engine is not stopped and travels in the HEV mode.
As a result, in addition to reducing the start shock frequency due to engine stop / start, vehicle speed fluctuations due to EV-HEV torque steps are also suppressed, improving drivability.

In constant speed cruise, the automatic braking request torque calculator calculates the cruise request torque from the deviation between the target vehicle speed and the actual vehicle speed, so even if there is a deviation between the target engine torque and the actual engine torque, the change appears in the vehicle speed. Otherwise, there is no effect on controllability.
In the present embodiment described above, as illustrated in FIG. 14, the case where the engine stop determination value is corrected to be small according to the deviation between the target engine torque and the actual engine torque is illustrated. Alternatively, the engine stop determination value may be corrected to be smaller in a step-like manner as the deviation becomes larger.
Here, the engine start / stop determination processing unit 21Ea and the engine stop control unit 21G constitute an engine stop processing unit. Step S320 constitutes a correction estimation unit. Step S360 constitutes a stop determination value correction unit.

(Effect of this embodiment)
(1) The engine stop processing unit stops driving of the drive wheels by the engine when the target traveling state is equal to or less than a preset engine stop determination value. The deviation estimation unit estimates a deviation between the target engine torque and the actual engine torque. The engine stop determination value correction unit corrects the engine stop determination value based on the deviation estimated by the deviation estimation unit.
It is possible to reduce the occurrence of engine stop / start hunting due to fluctuations in actual engine torque by correcting the engine stop determination value for engine stop determination by reducing the difference between the target engine torque and actual engine torque. It becomes.
That is, when the actual engine torque is larger than the target engine torque, it is possible to suppress the hunting of the engine start / stop caused by the actual drive torque step after the engine is stopped and the EV mode travel is performed.

(2) The target running state value in the engine stop processing unit is a target driving torque.
Even when engine stop determination is made based on the target drive torque, the engine stop determination value in the engine stop determination is decreased and corrected according to the deviation state between the target engine torque and the actual engine torque. It is possible to reduce the occurrence of engine stop / start hunting due to fluctuations.
(3) The stop determination value correction unit corrects the engine stop determination value to be smaller as the deviation estimated by the deviation estimation unit is larger.
An appropriate determination can be made by switching the stop determination value according to the excess amount of the estimated torque, instead of switching the value stepwise depending on the magnitude relationship between the command torque and the estimated torque.
(4) The engine stop determination value before correction is a value corresponding to the vehicle speed.
Since the running resistance has a correlation with the vehicle speed, the engine stop determination can be performed more appropriately by setting the engine stop determination value before correction to a value according to the vehicle speed.

(5) The automatic control request torque calculation unit is activated by a driver's starting operation, and calculates an automatic travel request torque for automatically adjusting to a travel state set by the driver. The driver request torque calculator obtains the driver request torque based on the accelerator opening. Then, the larger one of the automatic travel request torque and the driver request torque is set as the target drive torque.
In a situation where an automatic travel request torque for automatically adjusting to the travel state set by the driver is calculated, for example, during constant speed cruise travel, the vehicle will travel at a target drive torque (cruise required torque) such as constant speed travel. However, at this time, as described above, by reducing the occurrence of engine stop / start hunting due to actual fluctuations in engine torque, it becomes possible to travel in a traveling state set by the driver.

(Modification)
(1) In the above embodiment, the case where the engine stop determination is determined based on whether the target drive torque is equal to or less than the engine stop determination value and the engine stop determination value is corrected according to the engine torque deviation is exemplified.
As described above, the engine start / stop determination is also made based on the accelerator opening. Therefore, the engine stop determination value for the accelerator opening may be corrected to decrease according to the engine torque deviation.
Note that the determination may be made exclusively so that the engine start determination is performed based on the target drive torque during auto-cruise control, and the engine start determination is performed based on the accelerator opening degree during non-auto cruise control.

(2) In the above embodiment, the case where the engine stop determination is made based on whether the target drive torque is equal to or less than the engine stop determination value is exemplified. Alternatively, the driving of the drive wheels by the engine may be stopped when the actual engine torque is equal to or less than a preset engine stop determination value.
An example of a time chart in this case is shown in FIG.
As shown in FIG. 15, in the case where the actual engine torque is higher than the target engine torque, even if the target engine torque is equal to or lower than the engine stop determination value, the HEV is maintained until the actual engine torque is equal to or lower than the engine stop determination value. The mode will be maintained.
This method is effective when the required power generation torque is not added to the target engine torque.
That is, in the second modification, in the control method in which the power generation request torque is not added to the target engine torque generated by the target drive torque, the above effect can be achieved by a simpler method. Become.

DESCRIPTION OF SYMBOLS 1 Engine 2 Motor 4 1st clutch 5 2nd clutch 7 Drive wheel 20 Accelerator sensor 21 Integrated controller 21A Required power generation torque calculation part 21B Request engine torque calculation part 21C Motor output possible torque calculation part 21D Target drive torque calculation part 21Da Driver request torque Calculation unit 21Db Automatic control required torque calculation unit 21Dc 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 21Ea Engine start / stop determination processing unit 21Eb Mode transition processing 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 21M engine stop determination value calculation unit 22 engine controller 23 motor controller Controller 23 motor controller 24 AT controller 25 the brake controller 26 battery controller 28 steering switch 31 vehicle controller

Claims (6)

A vehicle travel control device that controls the travel of a hybrid vehicle including an engine and a motor as a drive source for transmitting drive torque to drive wheels,
When the target running state is equal to or less than a preset engine stop determination value, an engine stop processing unit that stops driving the drive wheels by the engine;
A deviation estimator for estimating a deviation between the target engine torque and the actual engine torque;
A stop determination value correction unit that reduces and corrects the engine stop determination value based on the deviation estimated by the deviation estimation unit;
A vehicle travel control device comprising:   The vehicle travel control apparatus according to claim 1, wherein the target travel state value in the engine stop processing unit is a target drive torque.   The vehicle travel control device according to claim 1 or 2, wherein the stop determination value correction unit corrects the engine stop determination value to be smaller as the deviation estimated by the deviation estimation unit is larger.   The vehicle travel control apparatus according to any one of claims 1 to 3, wherein the engine stop determination value before correction is a value corresponding to a vehicle speed. An automatic control request torque calculating unit that is operated by a driver's starting operation and calculates an automatic driving request torque for automatically adjusting to a driving state set by the driver;
A driver request torque calculator that calculates the driver request torque based on the accelerator opening;
5. The vehicle travel control apparatus according to claim 1, wherein a larger value of the automatic travel request torque and the driver request torque is set as a target drive torque. 6. A vehicle travel control device that controls the travel of a hybrid vehicle including an engine and a motor as a drive source for transmitting drive torque to drive wheels,
When the actual engine torque is equal to or less than a predetermined engine stop determination value, the vehicle travel control device stops driving the drive wheels by the engine.

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