JP6787707B2 - Car - Google Patents

Description

The present invention relates to an automobile, and more particularly to an automobile including a motor and a battery.

Conventionally, as an automobile of this type, it has been proposed that a motor for traveling is provided and the motor is controlled so that a braking force acts on the vehicle when the accelerator is off (see, for example, Patent Document 1). In this automobile, when the accelerator is off, the braking force applied to the vehicle in the eco mode is smaller than that in the normal mode.

Japanese Unexamined Patent Publication No. 2013-35370

In the above-mentioned automobile, when the accelerator is off and the eco mode is set, the braking force is relatively small, so that the deceleration of the vehicle may be insufficient. Insufficient deceleration of the vehicle may reduce vehicle operability.

The main object of the automobile of the present invention is to suppress deterioration of vehicle operability.

The automobile of the present invention has adopted the following means in order to achieve the above-mentioned main object.

The automobile of the present invention
With a motor for running
A battery that exchanges power with the motor,
A control device that controls the motor so that braking force acts on the vehicle when the accelerator is off.
It is a car equipped with
When the accelerator is off, when the braking force reduction condition is satisfied, the control device accelerates the vehicle in the front-rear direction within a range equal to or less than the braking force when the reduction condition is not satisfied. The braking force is changed based on at least one of the lateral acceleration of the vehicle, the vertical acceleration of the vehicle, the yaw rate, the road surface gradient, and the friction coefficient of the road surface.
Car.

In the automobile of the present invention, when the accelerator is off, when the braking force reduction condition is satisfied, the acceleration in the front-rear direction of the vehicle is within the range equal to or less than the braking force when the reduction condition is not satisfied. The braking force is changed based on at least one of the left-right acceleration, the vertical acceleration of the vehicle, the yaw rate, the road surface gradient, and the friction coefficient of the road surface. Therefore, when the acceleration in the front-rear direction of the vehicle and the road surface gradient (the downhill road side is positive) are large, the braking force is increased compared to when the acceleration is small, so that the vehicle is decelerated, especially when the accelerator is off on the downhill road. Can be suppressed from becoming insufficient, and the deterioration of vehicle operability can be suppressed. In addition, when the absolute value of acceleration in the left-right direction of the vehicle or the absolute value of yaw rate is large, the braking force is increased compared to when it is small, so that the deceleration of the vehicle becomes insufficient, especially when turning with the accelerator off. It is possible to suppress the decrease in vehicle operability. Furthermore, when the absolute value of the vertical acceleration of the vehicle is large, the braking force is increased compared to when it is small, thereby suppressing insufficient deceleration of the vehicle, especially when the accelerator is off on a rough road. It is possible to suppress the deterioration of vehicle operability. In addition, when the coefficient of friction of the road surface is small, the braking force is increased compared to when it is large, so that the vehicle decelerates, especially when the accelerator is off on low mu roads (wet road surface, snowy road, frozen road, etc.). Can be suppressed from becoming insufficient, and the deterioration of vehicle operability can be suppressed. Here, as the "decrease condition", a condition in which the eco-switch for instructing the eco-mode that gives priority to fuel efficiency as compared with the normal mode is on can be mentioned.

In such an automobile of the present invention, the control device is said to be smaller when the braking force is smaller than when the reduction condition is satisfied and the reduction condition is not satisfied when the accelerator is off. When the state in which the acceleration in the front-rear direction of the vehicle is larger than the first acceleration continues for the first time, the braking force may be increased. In this way, it is possible to more appropriately suppress the increase in vehicle speed when the accelerator is off. When the vehicle speed increases when the accelerator is off, it is possible to consider the time when the accelerator is off on a downhill road. In this case, when the reduction condition is satisfied when the accelerator is off, the control device satisfies the braking force when the braking force is increased, and the reduction condition is satisfied when the accelerator is off. It may be increased to the braking force when it is not used. Further, in the control device, when the reduction condition is satisfied when the accelerator is off, the state in which the acceleration in the front-rear direction of the vehicle is larger than the first acceleration continues for the first time. When the state in which the acceleration in the front-rear direction of the vehicle is equal to or lower than the first acceleration and equal to or lower than the second acceleration continues for the second time, the braking force may be reduced.

Further, in the automobile of the present invention, the control device reduces the braking force as compared with the case where the reduction condition is satisfied when the accelerator is off and the reduction condition is not satisfied. When the road surface gradient is larger than the first gradient when the downhill road side is positive, the braking force may be increased when the state continues for the third time. In this way, it is possible to more appropriately secure the deceleration when the accelerator is off on the downhill road. In this case, when the reduction condition is satisfied when the accelerator is off, the control device satisfies the braking force when the braking force is increased, and the reduction condition is satisfied when the accelerator is off. It may be increased to the braking force when it is not used. Further, in the control device, when the reduction condition is satisfied when the accelerator is off, the road surface gradient becomes higher after the state in which the road surface gradient is larger than the first gradient continues for the third time. When the state of the first gradient or less and the second gradient or less continues for the fourth time, the braking force may be reduced.

Further, in the automobile of the present invention, when the control device reduces the braking force as compared with the case where the reduction condition is satisfied and the reduction condition is not satisfied when the accelerator is off. When the state in which the absolute value of the acceleration in the left-right direction of the vehicle is larger than the third acceleration continues for the fifth time, the braking force may be increased. In this way, it is possible to more appropriately secure the deceleration when turning with the accelerator off. In this case, when the reduction condition is satisfied when the accelerator is off, the control device satisfies the braking force when the braking force is increased, and the reduction condition is satisfied when the accelerator is off. It may be increased to the braking force when it is not used. Further, in the control device, when the reduction condition is satisfied when the accelerator is off, the absolute value of the acceleration in the left-right direction of the vehicle is larger than the third acceleration for the fifth time. When the absolute value of the left-right acceleration of the vehicle is the third acceleration or less and the fourth acceleration or less continues for the sixth time after the continuation, the braking force may be reduced.

In addition, in the automobile of the present invention, when the control device reduces the braking force as compared with the case where the reduction condition is satisfied when the accelerator is off and the reduction condition is not satisfied. When the state in which the absolute value of the yaw rate is larger than the first value continues for the seventh hour, the braking force may be increased. In this way, it is possible to more appropriately secure the deceleration when turning with the accelerator off. In this case, when the reduction condition is satisfied when the accelerator is off, the control device satisfies the braking force when the braking force is increased, and the reduction condition is satisfied when the accelerator is off. It may be increased to the braking force when it is not used. Further, in the control device, when the reduction condition is satisfied when the accelerator is off, the yaw rate is maintained after the absolute value of the yaw rate is larger than the first value for the seventh time. When the state in which the absolute value of is equal to or less than the first value and equal to or less than the second value continues for the eighth time, the braking force may be reduced.

In the automobile of the present invention, the control device is the vehicle when the braking force is reduced as compared with the case where the reduction condition is satisfied and the reduction condition is not satisfied when the accelerator is off. When the state in which the absolute value of the acceleration in the vertical direction is larger than the fifth acceleration continues for the ninth time, the braking force may be increased. In this way, it is possible to more appropriately secure the deceleration when the accelerator is off on a rough road. In this case, when the reduction condition is satisfied when the accelerator is off, the control device satisfies the braking force when the braking force is increased, and the reduction condition is satisfied when the accelerator is off. It may be increased to the braking force when it is not used. Further, in the control device, when the reduction condition is satisfied when the accelerator is off, the absolute value of the vertical acceleration of the vehicle is larger than the fifth acceleration for the ninth time. After the continuation, when the absolute value of the vertical acceleration of the vehicle is the fifth acceleration or less and the sixth acceleration or less continues for the tenth hour, the braking force may be reduced.

In the automobile of the present invention, the control device has the road surface when the reduction condition is satisfied when the accelerator is off and the braking force is reduced as compared with the case where the reduction condition is not satisfied. When the state in which the friction coefficient of is less than the third value continues for the eleventh hour, the braking force may be increased. In this way, it is possible to more appropriately secure the deceleration when the accelerator is off on the low mu road. In this case, when the reduction condition is satisfied when the accelerator is off, the control device satisfies the braking force when the braking force is increased, and the reduction condition is satisfied when the accelerator is off. It may be increased to the braking force when it is not used. Further, in the control device, when the reduction condition is satisfied when the accelerator is off, the state where the friction coefficient of the road surface is less than the third value continues for the eleventh hour, and then the road surface When the state in which the friction coefficient is the third value or more and the fourth value or more continues for the twelfth time, the braking force may be reduced.

It is a block diagram which shows the outline of the structure of the hybrid vehicle 20 as an Example of this invention. It is a flowchart which shows an example of the accelerator-off time control routine executed by the HVECU 70 of an Example. It is explanatory drawing which shows an example of the required torque setting map. It is a flowchart which shows an example of the braking force reduction flag setting routine. It is explanatory drawing which shows an example of the state when the accelerator is off and the driving mode Md is an eco mode (the reduction condition is satisfied). It is explanatory drawing which shows an example of the relationship between the anteroposterior acceleration α and the threshold value Caref and the threshold value Cbref. It is a flowchart which shows an example of the braking force reduction flag setting routine. It is explanatory drawing which shows an example of the relationship between the road surface gradient θrg and the threshold value Ccref and the threshold value Cdreff. It is a flowchart which shows an example of the braking force reduction flag setting routine. It is explanatory drawing which shows an example of the relationship between the absolute value of the lateral acceleration β, the threshold value Caref and the threshold value Cbref. It is a flowchart which shows an example of the braking force reduction flag setting routine. It is explanatory drawing which shows an example of the relationship between the absolute value of yaw rate θyr and the threshold value Cgref and the threshold value Cref. It is a flowchart which shows an example of the braking force reduction flag setting routine. It is explanatory drawing which shows an example of the relationship between the absolute value of the vertical acceleration γ and the threshold value Ciref and the threshold value Cjref. It is a flowchart which shows an example of the braking force reduction flag setting routine. It is explanatory drawing which shows an example of the relationship between the friction coefficient μ of a road surface, the threshold value Ckref and the threshold value Clref. It is explanatory drawing which shows the outline of the structure of the hybrid vehicle 120 of a modification. It is explanatory drawing which shows the outline of the structure of the electric vehicle 220 of a modification.

Next, a mode for carrying out the present invention will be described with reference to examples.

FIG. 1 is a configuration diagram showing an outline of the configuration of a hybrid vehicle 20 as an embodiment of the present invention. As shown in the figure, the hybrid vehicle 20 of the embodiment includes an engine 22, a planetary gear 30, motors MG1 and MG2, inverters 41 and 42, a battery 50, and an electronic control unit for hybrid (hereinafter referred to as "HVECU"). 70 and.

The engine 22 is configured as an internal combustion engine that outputs power using gasoline, light oil, or the like as fuel. The engine 22 is operated and controlled by an electronic control unit for an engine (hereinafter, referred to as "engine ECU") 24.

Although not shown, the engine ECU 24 is configured as a microprocessor centered on a CPU, and includes a ROM for storing a processing program, a RAM for temporarily storing data, an input / output port, and a communication port in addition to the CPU. .. Signals from various sensors required to control the operation of the engine 22, for example, a crank angle θcr from a crank position sensor that detects the rotational position of the crankshaft 26 of the engine 22, are input to the engine ECU 24 from an input port. ing. Various control signals for controlling the operation of the engine 22 are output from the engine ECU 24 via the output port. The engine ECU 24 is connected to the HVECU 70 via a communication port. The engine ECU 24 calculates the rotation speed Ne of the engine 22 based on the crank angle θcr from the crank position sensor 23.

The planetary gear 30 is configured as a single pinion type planetary gear mechanism. The rotor of the motor MG1 is connected to the sun gear of the planetary gear 30. A drive shaft 36 connected to the drive wheels 39a and 39b via a differential gear 38 is connected to the ring gear of the planetary gear 30. The crankshaft 26 of the engine 22 is connected to the carrier of the planetary gear 30 via a damper 28.

The motor MG1 is configured as, for example, a synchronous motor generator, and as described above, the rotor is connected to the sun gear of the planetary gear 30. The motor MG2 is configured as, for example, a synchronous motor generator, and a rotor is connected to a drive shaft 36. The inverters 41 and 42 are connected to the motors MG1 and MG2 and also to the battery 50 via the power line 54. The motors MG1 and MG2 are rotationally driven by switching control of a plurality of switching elements (not shown) of the inverters 41 and 42 by an electronic control unit for a motor (hereinafter referred to as "motor ECU") 40.

Although not shown, the motor ECU 40 is configured as a microprocessor centered on a CPU, and includes a ROM for storing a processing program, a RAM for temporarily storing data, an input / output port, and a communication port in addition to the CPU. .. The motor ECU 40 has signals from various sensors required to drive and control the motors MG1 and MG2, for example, rotation positions θm1 from rotation position detection sensors 43 and 44 that detect the rotation positions of the rotors of the motors MG1 and MG2. , Θm2, etc. are input via the input port. From the motor ECU 40, switching control signals and the like to a plurality of switching elements (not shown) of the inverters 41 and 42 are output via the output port. The motor ECU 40 is connected to the HVECU 70 via a communication port. The motor ECU 40 calculates the rotation speeds Nm1 and Nm2 of the motors MG1 and MG2 based on the rotation positions θm1 and θm2 of the rotors of the motors MG1 and MG2 from the rotation position detection sensors 43 and 44.

The battery 50 is configured as, for example, a lithium ion secondary battery or a nickel hydrogen secondary battery, and is connected to the inverters 41 and 42 via a power line 54. The battery 50 is managed by a battery electronic control unit (hereinafter, referred to as “battery ECU”) 52.

Although not shown, the battery ECU 52 is configured as a microprocessor centered on a CPU, and includes a ROM for storing a processing program, a RAM for temporarily storing data, an input / output port, and a communication port in addition to the CPU. .. Signals from various sensors necessary for managing the battery 50 are input to the battery ECU 52 via the input port. The signals input to the battery ECU 52 include, for example, the battery voltage Vb from the voltage sensor 51a installed between the terminals of the battery 50, the battery current Ib from the current sensor 51b attached to the output terminal of the battery 50, and the battery 50. The battery temperature Tb from the temperature sensor 51c attached to the above can be mentioned. The battery ECU 52 is connected to the HVECU 70 via a communication port. The battery ECU 52 calculates the storage ratio SOC based on the integrated value of the battery current Ib from the current sensor 51b. The storage ratio SOC is the ratio of the capacity of electric power that can be discharged from the battery 50 to the total capacity of the battery 50.

Although not shown, the HVECU 70 is configured as a microprocessor centered on a CPU, and includes a ROM for storing a processing program, a RAM for temporarily storing data, an input / output port, and a communication port in addition to the CPU. Signals from various sensors are input to the HVECU 70 via input ports. Examples of the signal input to the HVECU 70 include an ignition signal from the ignition switch 80 and a shift position SP from the shift position sensor 82 that detects the operating position of the shift lever 81. Here, the shift position SP includes a parking position (P position), a reverse position (R position), a neutral position (N position), a forward position (D position), and the like. Further, the accelerator opening Acc from the accelerator pedal position sensor 84 that detects the depression amount of the accelerator pedal 83, the brake pedal position BP from the brake pedal position sensor 86 that detects the depression amount of the brake pedal 85, and the vehicle speed that detects the vehicle speed. The vehicle speed V from the sensor 88 can also be mentioned. Further, as the traveling mode Md, an eco-switch signal from the eco-switch 90 that indicates an eco-mode in which fuel efficiency is prioritized as compared with the normal mode can also be mentioned. The front-rear acceleration α, the left-right acceleration β, and the up-down acceleration γ from the acceleration sensor 91 that detects the acceleration in the front-rear direction, the left-right direction, and the up-down direction of the vehicle can also be mentioned. Examples include the yaw rate θyr from the yaw rate sensor 92 that detects the yaw rate, the road surface gradient θrg from the gradient sensor 93 that detects the slope of the road surface, and the raindrop amount QR from the rain sensor 94 that detects the amount of raindrops on the windshield. The HVECU 70 estimates the coefficient of friction μ of the road surface based on the amount of raindrops QR so that the larger the amount of raindrops Qr, the smaller the coefficient of friction μ. Further, the HVECU 70 outputs a control signal or the like to the wiper operating device 96 that automatically operates the wiper via the output port. The wiper operating device 96 operates the wiper at a higher speed as the amount of raindrops QR increases. As described above, the HVECU 70 is connected to the engine ECU 24, the motor ECU 40, and the battery ECU 52 via a communication port.

In the hybrid vehicle 20 of the embodiment configured in this way, the required driving force of the drive shaft 36 is set based on the accelerator opening degree Acc and the vehicle speed V, and the required power corresponding to the required driving force is output to the drive shaft 36. In addition, the engine 22 and the motors MG1 and MG2 are operated and controlled. The operation modes of the engine 22 and the motors MG1 and MG2 include the following modes (1) to (3).
(1) Torque conversion operation mode: The engine 22 is operated and controlled so that the power corresponding to the required power is output from the engine 22, and all the power output from the engine 22 is the planetary gear 30 and the motors MG1 and MG2. Mode in which the motors MG1 and MG2 are driven and controlled so that the required power is output to the drive shaft 36 by torque conversion by (2) Charge / discharge operation mode: The sum of the required power and the power required for charging / discharging the battery 50. The engine 22 is operated and controlled so that the power corresponding to the above is output from the engine 22, and all or part of the power output from the engine 22 is charged and discharged from the battery 50 to the planetary gear 30 and the motors MG1 and MG2. Mode in which the motors MG1 and MG2 are driven and controlled so that the required power is output to the drive shaft 36 by torque conversion by (3) Motor operation mode: The operation of the engine 22 is stopped and the required power is transferred to the drive shaft 36. Mode to drive and control the motor MG2 so that it is output

Next, the operation of the hybrid vehicle 20 of the embodiment configured in this way, particularly the operation when the accelerator is off during traveling will be described. FIG. 2 is a flowchart showing an example of an accelerator off control routine executed by the HVECU 70 of the embodiment. This routine is repeatedly executed every predetermined time (for example, several msec) when the accelerator is off during traveling. When the accelerator is off during driving, in parallel with this routine, the engine 22 is stopped by the coordinated control of the HVECU 70, the engine ECU 24, and the motor ECU 40, and a plurality of inverters 41 are used so that torque is not output from the motor MG1. Performs switching control of the switching element.

When the accelerator off control routine is executed, the HVECU 70 first inputs the vehicle speed V and the braking force reduction flag Fbr (step S100). Here, the vehicle speed V is assumed to be the one detected by the vehicle speed sensor 88. The braking force reduction flag Fbr is a flag indicating whether or not to reduce the braking force when the accelerator is off, and the flag set by the braking force reduction flag setting routine described later is input.

When the data is input in this way, the required torque Td * required for the vehicle (required for the drive shaft 36) is set based on the input vehicle speed V and the braking force reduction flag Fbr (step S110). Here, in the embodiment, the required torque Td * is stored in a ROM (not shown) as a required torque setting map by predetermining the relationship between the vehicle speed V, the braking force reduction flag Fbr, and the required torque Td *, and the vehicle speed V. And the braking force reduction flag Fbr are given, the corresponding required torque Td * is derived from this map and set. An example of the required torque setting map is shown in FIG. When the required torque Td * is negative, it means that the braking torque is required for the vehicle (drive shaft 36). As shown in the figure, the required torque Td * is set so as to be larger (smaller as the braking force) when the braking force reduction flag Fbr is 1 than when the value is 0. Specifically, when the braking force reduction flag Fbr is a value 0, the value Tdno is set in the required torque Td *, and when the braking force reduction flag Fbr is a value 1, the required torque Td * is larger than the value Tdno (braking). The value Tdec (small as torque) was set.

When the required torque Td * is set in this way, the set required torque Td * is set as the torque command Tm2 * of the motor MG2 and transmitted to the motor ECU 40 (step S120) to end this routine. When the motor ECU 40 receives the torque command Tm2 * of the motor MG2, the motor ECU 40 performs switching control of a plurality of switching elements of the inverter 42 so that the motor MG2 is driven by the torque command Tm2 *. When the required torque Td *, that is, the torque command Tm2 * of the motor MG2 is negative (when the braking torque is), the regenerative drive of the motor MG2 outputs a negative torque, that is, the braking torque to the drive shaft 36. By such control, when the braking force reduction flag Fbr is a value 1, the required torque Td *, that is, the torque command Tm2 * of the motor MG2 is larger (the braking force is smaller) than when the braking force reduction flag Fbr is a value 0. ) To control the motor MG2. Therefore, hereinafter, the control when the braking force reduction flag Fbr is a value 1 is referred to as "braking force reduction control".

Next, the process of setting the braking force reduction flag Fbr used in the accelerator off control routine of FIG. 2 will be described. FIG. 4 is a flowchart showing an example of the braking force reduction flag setting routine. This routine is repeatedly executed at predetermined time (for example, several msec) in parallel with the routine of FIG. 2 when the accelerator is off during traveling.

When the braking force reduction flag setting routine is executed, the HVECU 70 first inputs the traveling mode Md and the front-rear acceleration α (step S200). Here, the traveling mode Md is set to be input based on the eco-switch signal from the eco-switch 90 (normal mode or eco-mode). As the front-back acceleration α, the one detected by the acceleration sensor 91 is input.

When the data is input in this way, it is determined whether the traveling mode Md is the normal mode or the eco mode (step S210). This process is a process for determining whether or not the braking force reduction condition (condition for instructing the execution of the braking force reduction control described above) when the accelerator is off is satisfied. When it is determined that the driving mode Md is the normal mode (not the eco mode), it is determined that the reduction condition is not satisfied, the braking force reduction flag Fbr is set to a value 0 (step S330), and this routine is executed. finish.

When it is determined in step S210 that the travel mode Md is the eco mode, it is determined whether or not it is immediately after the start of accelerator off or immediately after the switching of the travel mode Md (step S220). As a case where the traveling mode Md is in the eco mode and immediately after the accelerator is off in steps S210 and S220, it can be considered that the traveling mode Md is in the eco mode and immediately after the accelerator is released from the accelerator on state. Further, as a case where the traveling mode Md is in the eco mode and immediately after the switching of the traveling mode Md in steps S210 and S220, it can be considered immediately after the traveling mode Md is switched from the normal mode to the eco mode while the accelerator is off. When it is determined in step S220 immediately after the accelerator off is started or immediately after the traveling mode Md is switched, the braking force reduction flag Fbr is set to a value 1 (step S320), and this routine is terminated.

When it is determined in step S220 that it is not immediately after the start of accelerator off and immediately after the switching of the traveling mode Md, the front-rear acceleration α is compared with the threshold value αref1 (step S230). Here, the threshold value αref1 is a threshold value for determining whether or not it is tentatively determined that the vehicle speed V is increasing. For example, 0G (1G = 9.8 m / s ² ) or 0.02G, 0. 04G or the like can be used. When the vehicle speed V increases when the accelerator is off, it is possible to consider the time when the accelerator is off on a downhill road. When the front-rear acceleration α is larger than the threshold value αref1, it is tentatively determined that the vehicle speed V is increasing, and the counter Ca is counted up by a value of 1 (step S240). On the other hand, when the front-rear acceleration α is equal to or less than the threshold value αref1, it is not tentatively determined that the vehicle speed V is increasing (the tentative determination is canceled when the tentative determination is made), and the counter Ca is cleared (reset) to a value of 0. (Step S250). Here, the product of the counter Ca and the execution interval of this routine means the duration for which it is tentatively determined that the vehicle speed V is increasing.

Subsequently, the front-back acceleration α is compared with the threshold value αref2 equal to or less than the threshold value αref1 (step S260). Here, the threshold value αref2 is a threshold value for determining whether or not it is tentatively determined that the vehicle speed V has not increased, and for example, −0.04G, −0.02G, 0G, or the like can be used. When the front-rear acceleration α is equal to or less than the threshold value αref2, it is tentatively determined that the vehicle speed V has not increased, and the counter Cb is counted up by a value of 1 (step S270). On the other hand, when the front-rear acceleration α is larger than the threshold value αref2, it is not tentatively determined that the vehicle speed V has not increased (the tentative determination is canceled when the tentative determination is made), and the counter Cb is cleared to a value of 0 (reset). (Step S280). Here, the product of the counter Cb and the execution interval of this routine means the duration for which it is tentatively determined that the vehicle speed V has not increased.

When the counter Ca and the counter Cb are set in this way, the counter Ca is compared with the threshold value Caref (step S290), and the counter Cb is compared with the threshold value Cbref (step S300). Here, the threshold value Caref is a threshold value for determining whether or not the vehicle speed V is actually determined (determined), and for example, a value corresponding to 400 msec, 450 msec, 500 msec, or the like can be used. .. The threshold value Cbref is a threshold value for determining whether or not this determination (determination) is made that the vehicle speed V has not increased, and for example, values corresponding to 400 msec, 450 msec, 500 msec, and the like can be used.

In steps S290 and S300, when the counter Ca is less than the threshold value Caref and less than the counter Cbref, this determination (confirmation) is not made whether the vehicle speed V is increasing or not, and at the time of the previous execution of this routine. Check the value of the set braking force reduction flag (previous Fbr) (step S310). Then, when the previous braking force reduction flag (previous Fbr) is a value 1, the value 1 is set in the braking force reduction flag Fbr (step S320), and this routine is terminated. On the other hand, when the previous braking force reduction flag (previous Fbr) is a value 0, the value 0 is set in the braking force reduction flag Fbr (step S330), and this routine is terminated.

When the counter Ca is equal to or higher than the threshold value Caref in step S290, it is determined (confirmed) that the vehicle speed V is increasing, a value 0 is set in the braking force reduction flag Fbr (step S330), and this routine is terminated. .. Therefore, when the braking force reduction flag Fbr reaches a value of 1 and the counter Ca reaches the threshold value Caref or higher, the braking force reduction flag Fbr is switched to a value of 0. As a result, when the driving mode Md is in the eco mode (when the condition for reducing the braking force when the accelerator is off is satisfied), it is determined that the vehicle speed V is increasing during the execution of the braking force reduction control. , The execution of the braking force reduction control is stopped, and the required torque Td * is reduced (the braking force is increased). As a result, it is possible to suppress insufficient deceleration when the accelerator is off, and to suppress deterioration of vehicle operability, as compared with the case where the braking torque is continued with a relatively small torque. it can.

When the counter Cb is equal to or higher than the threshold value Cbref in step S300, it is determined (confirmed) that the vehicle speed V has not increased, a value 1 is set in the braking force reduction flag Fbr (step S320), and this routine is terminated. .. Therefore, when the braking force reduction flag Fbr reaches a value of 0 and the counter Cb reaches the threshold value Cbref or higher, the braking force reduction flag Fbr is switched to the value 1. As a result, when the driving mode Md is in the eco mode, it is determined that the vehicle speed V has not increased when the braking force reduction control is not executed (when the execution is stopped (interrupted)). The execution of the power reduction control is restarted, and the required torque Td * is increased (the braking force is decreased). As a result, it is possible to respond to the intention of the driver who has the eco-switch 90 turned on (it is considered that he / she desires to make the braking force relatively small).

FIG. 5 is an explanatory diagram showing an example of a state when the accelerator is off and the traveling mode Md is in the eco mode (the reduction condition is satisfied). As shown in the figure, the front-rear acceleration α is between the threshold value αref1 and the threshold value αref2, the counters Ca and Cb are both values 0, and the required torque Td * is relatively large (relatively small as the braking torque) value Tdec (FIG. 3) In the state of), when the front-rear acceleration α becomes larger than the threshold value αref1 at time t1, the counter Ca starts to be increased. Then, when the counter Ca reaches the threshold value Caref or higher at time t2, the required torque Td * is reduced to the value Tdno (see FIG. 3) (the braking torque is increased). As a result, it is possible to suppress insufficient deceleration when the accelerator is off, and it is possible to suppress deterioration of vehicle operability. After that, when the front-back acceleration α becomes equal to or less than the threshold value αref1 at time t3, the counter Ca is cleared to a value 0, and when the front-back acceleration α becomes equal to or less than the threshold value αref2 at time t4, the counter Cb starts to increase, and at time t5, the counter Cb sets the threshold value Cbref When the above is reached, the required torque Td * is increased to the value Tdec (the braking torque is decreased). As a result, it is possible to respond to the intention of the driver who has the eco-switch 90 turned on. Then, when the front-rear acceleration α becomes larger than the threshold value αref2 at time t6, the counter Cb is cleared to a value of 0.

In the hybrid vehicle 20 of the embodiment described above, when the accelerator is off and the driving mode Md is the eco mode (the reduction condition is satisfied), the front-rear acceleration α is set from the threshold value αref1 during the execution of the braking force reduction control. When the counter Ca, which counts up when the value is large, reaches the threshold value Caref or higher, the required torque Td * is reduced (the braking torque is increased). As a result, it is possible to suppress insufficient deceleration when the accelerator is off, and to suppress deterioration of vehicle operability, as compared with the case where the braking torque is continued with a relatively small torque. it can. When the vehicle speed V increases when the accelerator is off, it is possible to consider the time when the accelerator is off on a downhill road.

In the hybrid vehicle 20 of the embodiment, a uniform value (fixed value) is used for the threshold value Caref and the threshold value Cbref. However, at least one of the threshold value Caref and the threshold value Cbref may be set based on the longitudinal acceleration α. When the threshold value Caref and the threshold value Cbref are set based on the front-back acceleration α, the relationship between the front-back acceleration α and the threshold value Caref and the threshold value Cbref is predetermined and stored in a ROM (not shown) as a map, and the front-back acceleration α is given. , The corresponding threshold Caref and threshold Cbref may be derived from this map. FIG. 6 shows an example of the relationship between the anteroposterior acceleration α and the threshold value Caref and the threshold value Cbref. As shown in the figure, the threshold value Caref is set to be smaller when the front-back acceleration α is large than when it is small. This is because when the braking force reduction flag Fbr is a value 1 (when braking force reduction control is being executed), the larger the front-rear acceleration α, the larger the acceleration of the vehicle speed V, so the vehicle operation when the accelerator is off. This is because it is preferable to switch the braking force reduction flag Fbr to a value of 0 (stop the braking force reduction control) at an early stage in order to further secure the property. Further, as shown in the figure, the threshold value Caref is set to be smaller when the front-back acceleration α is small than when it is large. This is because when the braking force reduction flag Fbr is 0 (when the braking force reduction control is stopped), the smaller the front-rear acceleration α, the larger the deceleration of the vehicle speed V, so the braking force reduction flag is set earlier. This is because it is considered unlikely that the vehicle operability will become a problem even if the Fbr is switched to the value 1 (even if the braking force reduction control is restarted).

In the hybrid vehicle 20 of the embodiment, when the accelerator is off and the driving mode Md is the eco mode, the braking force reduction flag Fbr is set when the counter Ca reaches the threshold value Caref or more when the braking force reduction flag Fbr is a value of 1. By switching to the value 0, the required torque Td * is reduced to the value Tdno (the value when the braking force reduction flag Fbr is the value 0) (the braking torque is increased). However, the braking force reduction flag Fbr is continued at a value 1, and the required torque Td * is set within a range larger than the value Tdno and smaller than the value Tdec (value when the braking force reduction flag Fbr is a value 1). When the longitudinal acceleration α is large, it may be set to be smaller than when it is small.

In the hybrid vehicle 20 of the embodiment, when the accelerator is off and the traveling mode Md is the eco mode, the braking force reduction flag Fbr and the required torque Td * are set by using the counters Ca and Cb based on the front-rear acceleration α. However, instead of using the counters Ca and Cb, the required torque Td * may be set so that when the front-rear acceleration α is large, it becomes smaller (the braking torque becomes larger) than when it is small.

In the hybrid vehicle 20 of the embodiment, when the accelerator is off and the traveling mode Md is the eco mode, the braking force reduction flag Fbr and the required torque Td * are set by using the front-rear acceleration α. However, instead of the front-rear acceleration α, any one of the left-right acceleration β, the vertical acceleration γ, the yaw rate θyr, the road surface gradient θrg, and the friction coefficient μ of the road surface may be used. Further, a plurality of of the front-rear acceleration α, the left-right acceleration β, the vertical acceleration γ, the yaw rate θyr, the road surface gradient θrg, and the friction coefficient μ of the road surface may be used. Hereinafter, the cases where the road surface gradient θrg is used, the left-right acceleration β is used, the yaw rate θyr is used, the vertical acceleration γ is used, and the friction coefficient μ of the road surface is used will be described in order.

First, a case where the braking force reduction flag Fbr and the required torque Td * are set by using the road surface gradient θrg when the accelerator is off and the traveling mode Md is the eco mode will be described. In this case, the accelerator off control routine of FIG. 2 is executed, and the braking force reduction flag setting routine of FIG. 7 is executed instead of the braking force reduction flag setting routine of FIG. The braking force reduction flag setting routine of FIG. 7 is shown in FIG. 4 except that the processing of steps S200b and S230b to 300b is executed instead of the processing of steps S200 and S230 to S300 of the braking force reduction flag setting routine of FIG. It is the same as the braking force reduction flag setting routine. Therefore, among the braking force reduction flag setting routines of FIG. 7, the same step numbers are assigned to the same processes as those of the braking force reduction flag setting routine of FIG. Hereinafter, the braking force reduction flag setting routine of FIG. 7 will be described focusing on the points different from the braking force reduction control routine of FIG.

When the braking force reduction flag setting routine of FIG. 7 is executed, the HVECU 70 first inputs the traveling mode Md and the road surface gradient θrg (step S200b). Here, the input method of the traveling mode Md has been described above. As the road surface gradient θrg, the one detected by the gradient sensor 93 (the downhill road side is positive) is input.

When the data is input in this way, it is determined whether the driving mode Md is the normal mode or the eco mode (step S210), and when it is determined that the driving mode Md is the normal mode (not the eco mode), the braking force reduction flag Fbr is set to a value. Set 0 (step S330) to end this routine.

When it is determined in step S210 that the driving mode Md is the eco mode, it is determined whether or not the vehicle is immediately after the accelerator off is started or immediately after the driving mode Md is switched (step S220), and immediately after the accelerator is off or in the driving mode Md. When it is determined that the switching has just been performed, the value 1 is set in the braking force reduction flag Fbr (step S320), and this routine is terminated.

When it is determined in step S220 that it is not immediately after the start of accelerator off and immediately after the switching of the traveling mode Md, the road surface gradient θrg is compared with the threshold value θrgref1 (step S230b). Here, the threshold value θrgref1 is a threshold value for determining whether or not it is tentatively determined that the road is a downhill road (the vehicle speed V is likely to increase). When the road surface gradient θrg is larger than the threshold value θrgref1, it is tentatively determined that the road is a downhill road, and the counter Cc is counted up by a value of 1 (step S240b). On the other hand, when the road surface gradient θrg is equal to or less than the threshold value θrgref1, the tentative determination is not made as a downhill road (the tentative determination is canceled when the tentative determination is made), and the counter Cc is cleared (reset) to a value of 0 (step S250b). .. Here, the product of the counter Cc and the execution interval of this routine means the duration of provisionally determining that the road is a downhill road.

Subsequently, the road surface gradient θrg is compared with the threshold value θrgref2 equal to or less than the threshold value θrgref1 (step S260b). Here, the threshold value θrgref2 is a threshold value for determining whether or not it is tentatively determined that the road is not a downhill road. When the road surface gradient θrg is equal to or less than the threshold value θrgref2, it is tentatively determined that the road is not a downhill road, and the counter Cd is counted up by a value of 1 (step S270b). On the other hand, when the road surface gradient θrg is larger than the threshold value θrgref2, the tentative determination is not made unless the road is a downhill road (the tentative determination is canceled when the tentative determination is made), and the counter Cd is cleared (reset) to the value 0 (step S280b). .. Here, the product of the counter Cd and the execution interval of this routine means the duration for which it is tentatively determined that the road is not a downhill road.

When the counter Cc and the counter Cd are set in this way, the counter Cc is compared with the threshold value Ccref (step S290b), and the counter Cd is compared with the threshold value Cdref (step S300b). Here, the threshold value Ccref is a threshold value for determining whether or not this determination (determination) is made as a downhill road (the vehicle speed V is likely to increase). The threshold value CDref is a threshold value for determining whether or not this determination (determination) is made if the road is not a downhill road. A uniform value (fixed value) was used for the threshold value Ccref and the threshold value Cref.

In steps S290b and S300b, when the counter Cc is less than the threshold value Ccref and less than the counter Cdef, this determination (confirmation) is not performed regardless of whether the road is a downhill road or a downhill road, and the braking force reduction flag set at the time of the previous execution of this routine is not performed. Check the value of (previous Fbr) (step S310). Then, when the previous braking force reduction flag (previous Fbr) is a value 1, the value 1 is set in the braking force reduction flag Fbr (step S320), and this routine is terminated. On the other hand, when the previous braking force reduction flag (previous Fbr) is a value 0, the value 0 is set in the braking force reduction flag Fbr (step S330), and this routine is terminated.

When the counter Cc is equal to or higher than the threshold value Ccref in step S290b, it is determined (determined) that the road is a downhill road, a value 0 is set in the braking force reduction flag Fbr (step S330), and this routine is terminated. Therefore, when the braking force reduction flag Fbr reaches a value of 1 and the counter Cc reaches the threshold value Ccref or higher, the braking force reduction flag Fbr is switched to a value of 0. As a result, when the driving mode Md is in the eco mode (when the condition for reducing the braking force when the accelerator is off is satisfied), the road is downhill during the execution of the braking force reduction control (the vehicle speed V is likely to increase). ), The execution of the braking force reduction control is stopped, and the required torque Td * is reduced (the braking force is increased). As a result, it is possible to suppress insufficient deceleration when the accelerator is off (when the vehicle speed V is likely to increase) on a downhill road, as compared with the case where the braking torque is continuously maintained with a relatively small torque. , It is possible to suppress the deterioration of vehicle operability.

When the counter Cd is equal to or higher than the threshold value CDref in step S300b, it is determined (confirmed) that the vehicle speed V has not increased, a value 1 is set in the braking force reduction flag Fbr (step S320), and this routine is terminated. .. Therefore, when the braking force reduction flag Fbr is a value 0 and the counter Cd reaches the threshold value CDref or higher, the braking force reduction flag Fbr is switched to the value 1. As a result, when the driving mode Md is in the eco mode, when it is determined that the road is not a downhill road when the braking force reduction control is not executed (when the execution is stopped (interrupted)), the braking force reduction control is executed. Is restarted to increase the required torque Td * (decrease the braking force). As a result, it is possible to respond to the intention of the driver who has turned on the eco switch 90.

In this modification, a uniform value (fixed value) is used for the threshold value Ccref and the threshold value CDref. However, at least one of the threshold value Ccref and the threshold value Cdreff may be set based on the road surface gradient θrg. When the threshold Ccref and the threshold Cdref are set based on the road surface gradient θrg, the relationship between the road surface gradient θrg and the threshold Ccref and the threshold Cdref is predetermined and stored in a ROM (not shown) as a map, and when the road surface gradient θrg is given. , The corresponding threshold Ccref and threshold Cdref may be derived from this map. FIG. 8 shows an example of the relationship between the road surface gradient θrg and the threshold value Ccref and the threshold value Cref. As shown in the figure, the threshold value Ccref is set to be smaller when the road surface gradient θrg is large than when it is small. This is because when the braking force reduction flag Fbr is a value 1 (when braking force reduction control is being executed), the larger the road surface gradient θrg, the larger the increase in vehicle speed V tends to be, so the accelerator on a downhill road. This is because it is preferable to switch the braking force reduction flag Fbr to a value of 0 (stop the braking force reduction control) at an early stage in order to further secure the vehicle operability when the vehicle is off. Further, as shown in the figure, the threshold value CDref is set so that when the road surface gradient θrg is small, it is smaller than when it is large. This is because when the braking force reduction flag Fbr is 0 (when the braking force reduction control is stopped), the smaller the road surface gradient θrg, the larger the deceleration of the vehicle speed V tends to be, so the braking force is reduced at an early stage. This is because even if the flag Fbr is switched to the value 1 (even if the braking force reduction control is restarted), it is considered unlikely that the vehicle operability will become a problem thereafter.

Further, in this modification, when the accelerator is off and the driving mode Md is the eco mode, the braking force reduction flag Fbr is set to a value when the counter Cc reaches the threshold value Ccref or more when the braking force reduction flag Fbr is a value 1. By switching to 0, the required torque Td * is reduced to the value Tdno (the value when the braking force reduction flag Fbr is 0) (the braking torque is increased). However, the braking force reduction flag Fbr is continued at a value 1, and the required torque Td * is set within a range larger than the value Tdno and smaller than the value Tdec (value when the braking force reduction flag Fbr is a value 1). When the road surface gradient θrg is large, it may be set to be smaller than when it is small.

Further, in this modification, when the accelerator is off and the traveling mode Md is the eco mode, the braking force reduction flag Fbr and the required torque Td * are set by using the counters Cc and Cd based on the road surface gradient θrg. However, instead of using the counters Cc and Cd, the required torque Td * may be set so that when the road surface gradient θrg is large, it becomes smaller (the braking torque becomes larger) than when it is small.

Next, a case where the braking force reduction flag Fbr and the required torque Td * are set by using the left-right acceleration β when the accelerator is off and the traveling mode Md is the eco mode will be described. In this case, the accelerator off control routine of FIG. 2 is executed, and the braking force reduction flag setting routine of FIG. 9 is executed instead of the braking force reduction flag setting routine of FIG. The braking force reduction flag setting routine of FIG. 9 is shown in FIG. 4 except that the processing of steps S200c and S230c to 300c is executed instead of the processing of steps S200 and S230 to S300 of the braking force reduction flag setting routine of FIG. It is the same as the braking force reduction flag setting routine. Therefore, among the braking force reduction flag setting routines of FIG. 9, the same steps are assigned to the same processes as the braking force reduction flag setting routine of FIG. Hereinafter, the braking force reduction flag setting routine of FIG. 9 will be described focusing on the points different from the braking force reduction control routine of FIG.

When the braking force reduction flag setting routine of FIG. 9 is executed, the HVECU 70 first inputs the traveling mode Md and the lateral acceleration β (step S200c). Here, the input method of the traveling mode Md has been described above. As the left-right acceleration β, the one detected by the acceleration sensor 91 is input.

When the data is input in this way, it is determined whether the driving mode Md is the normal mode or the eco mode (step S210), and when it is determined that the driving mode Md is the normal mode (not the eco mode), the braking force reduction flag Fbr is set to a value. Set 0 (step S330) to end this routine.

When it is determined in step S210 that the driving mode Md is the eco mode, it is determined whether or not the vehicle is immediately after the accelerator off is started or immediately after the driving mode Md is switched (step S220), and immediately after the accelerator is off or in the driving mode Md. When it is determined that the switching has just been performed, the value 1 is set in the braking force reduction flag Fbr (step S320), and this routine is terminated.

When it is determined in step S220 that it is not immediately after the start of accelerator off and immediately after the switching of the traveling mode Md, the absolute value of the left-right acceleration β is compared with the threshold value βref1 (step S230c). Here, the threshold value βref1 is a threshold value for determining whether or not it is tentatively determined that the turning amount of the vehicle is relatively large. When the absolute value of the left-right acceleration β is larger than the threshold value βref 1, it is tentatively determined that the turning amount of the vehicle is relatively large, and the counter Ce is counted up by the value 1 (step S240c). On the other hand, when the absolute value of the left-right acceleration β is equal to or less than the threshold value βref1, it is not tentatively determined that the turning amount of the vehicle is relatively large (the tentative determination is canceled when the tentative determination is made), and the counter Ce is cleared to a value of 0 ( Reset) (step S250c). Here, the product of the counter Ce and the execution interval of this routine means the duration for which it is tentatively determined that the turning amount of the vehicle is relatively large.

Subsequently, the absolute value of the left-right acceleration β is compared with the threshold value βref2 equal to or less than the threshold value βref1 (step S260c). Here, the threshold value βref2 is a threshold value for determining whether or not it is tentatively determined that the turning amount of the vehicle is relatively small. When the absolute value of the lateral acceleration β is equal to or less than the threshold value βref2, it is tentatively determined that the turning amount of the vehicle is relatively small, and the counter Cf is counted up by a value of 1 (step S270c). On the other hand, when the absolute value of the left-right acceleration β is larger than the threshold value βref2, it is not tentatively determined that the turning amount of the vehicle is relatively small (the tentative determination is canceled when the tentative determination is made), and the counter Cf is cleared to a value of 0. (Reset) (step S280c). Here, the product of the counter Cf and the execution interval of this routine means the duration for which it is tentatively determined that the turning amount of the vehicle is relatively small.

When the counter Ce and the counter Cf are set in this way, the counter Ce is compared with the threshold value Ceref (step S290c), and the counter Cf is compared with the threshold value Cref (step S300c). Here, the threshold value Ceref is a threshold value for determining whether or not this determination (determination) is made when the turning amount of the vehicle is relatively large. The threshold value Cref is a threshold value for determining whether or not the present determination (determination) is made when the turning amount of the vehicle is relatively small. A uniform value (fixed value) was used for the threshold value Ceref and the threshold value Cref.

In steps S290c and S300c, when the counter Ce is less than the threshold value Ceref and less than the counter Cref, this determination (confirmation) is not made whether the turning amount of the vehicle is relatively large or relatively small, and the setting is made at the time of the previous execution of this routine. Check the value of the braking force reduction flag (previous Fbr) (step S310). Then, when the previous braking force reduction flag (previous Fbr) is a value 1, the value 1 is set in the braking force reduction flag Fbr (step S320), and this routine is terminated. On the other hand, when the previous braking force reduction flag (previous Fbr) is a value 0, the value 0 is set in the braking force reduction flag Fbr (step S330), and this routine is terminated.

When the counter Ce is equal to or higher than the threshold value Ceref in step S290c, it is determined (confirmed) that the turning amount of the vehicle is relatively large, the value 0 is set to the braking force reduction flag Fbr (step S330), and this routine is terminated. .. Therefore, when the braking force reduction flag Fbr reaches a value of 1 and the counter Ce reaches the threshold value Ceref or higher, the braking force reduction flag Fbr is switched to a value of 0. As a result, when the driving mode Md is in the eco mode (when the condition for reducing the braking force when the accelerator is off is satisfied), it is determined that the turning amount of the vehicle is relatively large during the execution of the braking force reduction control. , The execution of the braking force reduction control is stopped, and the required torque Td * is reduced (the braking force is increased). As a result, it is possible to suppress insufficient deceleration when the accelerator is off and the turning amount of the vehicle is relatively large, as compared with the case where the braking torque is continued with a relatively small torque, and the vehicle operability can be suppressed. Can be suppressed from decreasing.

When the counter Cf is equal to or higher than the threshold value Cref in step S300c, it is determined (confirmed) that the turning amount of the vehicle is relatively small, a value 1 is set in the braking force reduction flag Fbr (step S320), and this routine is terminated. .. Therefore, when the braking force reduction flag Fbr reaches a value of 0 and the counter Cf reaches the threshold value Cfr or more, the braking force reduction flag Fbr is switched to the value 1. As a result, when the driving mode Md is in the eco mode, it is determined that the turning amount of the vehicle is relatively small when the braking force reduction control is not executed (when the execution is stopped (interrupted)). The execution of the power reduction control is restarted, and the required torque Td * is increased (decreased as the braking force). As a result, it is possible to respond to the intention of the driver who has turned on the eco switch 90.

In this modification, a uniform value (fixed value) is used for the threshold value Ceref and the threshold value Cref. However, at least one of the threshold value Ceref and the threshold value Cref may be set based on the left-right acceleration β. When the threshold value Ceref and the threshold value Cref are set based on the left-right acceleration β, the relationship between the absolute value of the left-right acceleration β and the threshold value Ceref and the threshold value Cref is stored in a ROM (not shown) as a map in advance, and the left-right acceleration β Given an absolute value, the corresponding thresholds Ceref and Cref may be derived from this map. FIG. 10 shows an example of the relationship between the absolute value of the lateral acceleration β and the threshold value Ceref and the threshold value Cref. As shown in the figure, the threshold value Ceref is set so that when the absolute value of the left-right acceleration β is large, it is smaller than when it is small. This is because when the braking force reduction flag Fbr is a value 1 (when braking force reduction control is being executed), it is considered that the larger the absolute value of the left-right acceleration β, the larger the turning amount of the vehicle. This is because it is preferable to switch the braking force reduction flag Fbr to a value of 0 (stop the braking force reduction control) at an early stage in order to further secure the vehicle operability when turning off. Further, as shown in the figure, the threshold value Cref is set so that when the absolute value of the left-right acceleration β is small, it is smaller than when it is large. This is because when the braking force reduction flag Fbr is a value 0 (when the braking force reduction control is stopped), the smaller the absolute value of the left-right acceleration β, the earlier the braking force reduction flag Fbr is switched to the value 1. This is because it is unlikely that vehicle operability will become a problem after that (even if braking force reduction control is restarted).

Further, in this modification, when the accelerator is off and the traveling mode Md is the eco mode, the braking force reduction flag Fbr is set to a value when the counter Ce reaches the threshold value Ceref or higher when the braking force reduction flag Fbr is a value 1. By switching to 0, the required torque Td * is reduced to the value Tdno (the value when the braking force reduction flag Fbr is 0) (the braking torque is increased). However, the braking force reduction flag Fbr is continued at a value 1, and the required torque Td * is set within a range larger than the value Tdno and smaller than the value Tdec (value when the braking force reduction flag Fbr is a value 1). When the absolute value of the left-right acceleration β is large, it may be set to be smaller than when it is small.

Further, in this modification, when the accelerator is off and the driving mode Md is the eco mode, the braking force reduction flag Fbr and the required torque Td * are set by using the counters Ce and Cf based on the absolute value of the left-right acceleration β. did. However, instead of using the counters Ce and Cf, the required torque Td * may be set so that when the absolute value of the left-right acceleration β is large, it becomes smaller (the braking torque becomes larger) than when it is small.

Next, a case where the braking force reduction flag Fbr and the required torque Td * are set by using the yaw rate θyr when the accelerator is off and the traveling mode Md is the eco mode will be described. In this case, the accelerator off control routine of FIG. 2 is executed, and the braking force reduction flag setting routine of FIG. 11 is executed instead of the braking force reduction flag setting routine of FIG. The braking force reduction flag setting routine of FIG. 11 is shown in FIG. 4 except that the processing of steps S200d and S230d to 300d is executed instead of the processing of steps S200 and S230 to S300 of the braking force reduction flag setting routine of FIG. It is the same as the braking force reduction flag setting routine. Therefore, among the braking force reduction flag setting routines of FIG. 11, the same step numbers are assigned to the same processes as those of the braking force reduction flag setting routine of FIG. Hereinafter, the braking force reduction flag setting routine of FIG. 11 will be described focusing on the points different from the braking force reduction control routine of FIG.

When the braking force reduction flag setting routine of FIG. 11 is executed, the HVECU 70 first inputs the traveling mode Md and the yaw rate θyr (step S200d). Here, the input method of the traveling mode Md has been described above. As the yaw rate θyr, the one detected by the yaw rate sensor 92 is input.

When the data is input in this way, it is determined whether the driving mode Md is the normal mode or the eco mode (step S210), and when it is determined that the driving mode Md is the normal mode (not the eco mode), the braking force reduction flag Fbr is set to a value. Set 0 (step S330) to end this routine.

When it is determined in step S210 that the driving mode Md is the eco mode, it is determined whether or not the vehicle is immediately after the accelerator off is started or immediately after the driving mode Md is switched (step S220), and immediately after the accelerator is off or in the driving mode Md. When it is determined that the switching has just been performed, the value 1 is set in the braking force reduction flag Fbr (step S320), and this routine is terminated.

When it is determined in step S220 that it is not immediately after the start of accelerator off and immediately after the switching of the traveling mode Md, the absolute value of the yaw rate θyr is compared with the threshold value θyrref1 (step S230d). Here, the threshold value θyrref1 is a threshold value for determining whether or not it is tentatively determined that the turning amount of the vehicle is relatively large. When the absolute value of the yaw rate θyr is larger than the threshold value θyrref1, it is tentatively determined that the turning amount of the vehicle is relatively large, and the counter Cg is counted up by the value 1 (step S240d). On the other hand, when the absolute value of the yaw rate θyr is equal to or less than the threshold value θyrref1, it is not tentatively determined that the turning amount of the vehicle is relatively large (the tentative determination is canceled when the tentative determination is made), and the counter Cg is cleared to the value 0 (reset). ) (Step S250d). Here, the product of the counter Cg and the execution interval of this routine means the duration for which it is tentatively determined that the turning amount of the vehicle is relatively large.

Subsequently, the absolute value of the yaw rate θyr is compared with the threshold value θyrref2 equal to or less than the threshold value θyrref1 (step S260d). Here, the threshold value θyrref2 is a threshold value for determining whether or not it is tentatively determined that the turning amount of the vehicle is relatively small. When the absolute value of the yaw rate θyr is equal to or less than the threshold value θyrref2, it is tentatively determined that the turning amount of the vehicle is relatively small, and the counter Ch is counted up by the value 1 (step S270d). On the other hand, when the absolute value of the yaw rate θyr is larger than the threshold value θyrref2, it is not tentatively determined that the turning amount of the vehicle is relatively small (the tentative determination is canceled when the tentative determination is made), and the counter Ch is cleared to a value of 0 (the tentative determination is canceled). (Reset) (step S280d). Here, the product of the counter Ch and the execution interval of this routine means the duration for which it is tentatively determined that the turning amount of the vehicle is relatively small.

When the counter Cg and the counter Ch are set in this way, the counter Cg is compared with the threshold value Cgref (step S290d), and the counter Ch is compared with the threshold value Chref (step S300d). Here, the threshold value Cgref is a threshold value for determining whether or not this determination (determination) is made when the turning amount of the vehicle is relatively large. The threshold value Chref is a threshold value for determining whether or not this determination (determination) is made when the turning amount of the vehicle is relatively small. A uniform value (fixed value) was used for the threshold Cgref and the threshold Cref.

In steps S290d and S300d, when the counter Cg is less than the threshold value Cgref and less than the counter Cref, this determination (confirmation) is not made whether the turning amount of the vehicle is relatively large or relatively small, and the setting is made at the time of the previous execution of this routine. Check the value of the braking force reduction flag (previous Fbr) (step S310). Then, when the previous braking force reduction flag (previous Fbr) is a value 1, the value 1 is set in the braking force reduction flag Fbr (step S320), and this routine is terminated. On the other hand, when the previous braking force reduction flag (previous Fbr) is a value 0, the value 0 is set in the braking force reduction flag Fbr (step S330), and this routine is terminated.

When the counter Cg is equal to or higher than the threshold value Cgref in step S290d, it is determined (confirmed) that the turning amount of the vehicle is relatively large, the value 0 is set to the braking force reduction flag Fbr (step S330), and this routine is terminated. .. Therefore, when the braking force reduction flag Fbr reaches a value of 1 and the counter Cg reaches the threshold value Cgref or higher, the braking force reduction flag Fbr is switched to a value of 0. As a result, when the driving mode Md is in the eco mode (when the condition for reducing the braking force when the accelerator is off is satisfied), it is determined that the turning amount of the vehicle is relatively large during the execution of the braking force reduction control. , The execution of the braking force reduction control is stopped, and the required torque Td * is reduced (the braking force is increased). As a result, it is possible to suppress insufficient deceleration when the accelerator is off and the turning amount of the vehicle is relatively large, as compared with the case where the braking torque is continued with a relatively small torque, and the vehicle operability can be suppressed. Can be suppressed from decreasing.

When the counter Ch is equal to or higher than the threshold value Chref in step S300d, it is determined (confirmed) that the turning amount of the vehicle is relatively small, a value 1 is set in the braking force reduction flag Fbr (step S320), and this routine is terminated. .. Therefore, when the braking force reduction flag Fbr reaches a value of 0 and the counter Ch reaches the threshold value Chref or higher, the braking force reduction flag Fbr is switched to the value 1. As a result, when the driving mode Md is in the eco mode, it is determined that the turning amount of the vehicle is relatively small when the braking force reduction control is not executed (when the execution is stopped (interrupted)). The execution of the power reduction control is restarted, and the required torque Td * is increased (decreased as the braking force). As a result, it is possible to respond to the intention of the driver who has turned on the eco switch 90.

In this modification, a uniform value (fixed value) is used for the threshold value Cfref and the threshold value Cref. However, at least one of the threshold Cgref and the threshold Cref may be set based on the yaw rate θyr. When the threshold Cgref and the threshold Cref are set based on the yaw rate θyr, the relationship between the absolute value of the yaw rate θyr and the threshold Cgref and the threshold Creff is stored in a ROM (not shown) as a map in advance, and the absolute value of the yaw rate θyr Given, the corresponding threshold Cgref and threshold Cref may be derived from this map. FIG. 12 shows an example of the relationship between the absolute value of the yaw rate θyr and the threshold Cgref and the threshold Cref. As shown in the figure, the threshold value Cgref is set so that when the absolute value of the yaw rate θyr is large, it is smaller than when it is small. This is because when the braking force reduction flag Fbr is a value 1 (when braking force reduction control is being executed), the larger the absolute value of the yaw rate θyr, the larger the turning amount of the vehicle, so that the vehicle turns with the accelerator off. This is because it is preferable to switch the braking force reduction flag Fbr to a value of 0 (stop the braking force reduction control) at an early stage in order to further secure the vehicle operability at the time. Further, as shown in the figure, the threshold value Chref is set so that when the absolute value of the yaw rate θyr is small, it is smaller than when it is large. This is because when the braking force reduction flag Fbr is 0 (when the braking force reduction control is stopped), the smaller the absolute value of the yaw rate θyr, the earlier the braking force reduction flag Fbr is switched to the value 1. This is because it is unlikely that vehicle operability will become a problem after that (even if braking force reduction control is restarted).

Further, in this modification, when the accelerator is off and the driving mode Md is the eco mode, the braking force reduction flag Fbr is set to a value when the counter Cg reaches the threshold value Cgref or more when the braking force reduction flag Fbr is a value 1. By switching to 0, the required torque Td * is reduced to the value Tdno (the value when the braking force reduction flag Fbr is 0) (the braking torque is increased). However, the braking force reduction flag Fbr is continued at a value 1, and the required torque Td * is set within a range larger than the value Tdno and smaller than the value Tdec (value when the braking force reduction flag Fbr is a value 1). When the absolute value of the yaw rate θyr is large, it may be set to be smaller than when it is small.

Further, in this modification, when the accelerator is off and the driving mode Md is the eco mode, the braking force reduction flag Fbr and the required torque Td * are set by using the counters Cg and Ch based on the absolute value of the yaw rate θyr. .. However, instead of using the counters Cg and Ch, the required torque Td * may be set so that when the absolute value of the yaw rate θyr is large, it becomes smaller (the braking torque becomes larger) than when it is small.

Next, a case where the braking force reduction flag Fbr and the required torque Td * are set by using the vertical acceleration γ when the accelerator is off and the traveling mode Md is the eco mode will be described. In this case, the accelerator off control routine of FIG. 2 is executed, and the braking force reduction flag setting routine of FIG. 13 is executed instead of the braking force reduction flag setting routine of FIG. The braking force reduction flag setting routine of FIG. 13 is shown in FIG. 4 except that the processing of steps S200e and S230e to 300e is executed instead of the processing of steps S200 and S230 to S300 of the braking force reduction flag setting routine of FIG. It is the same as the braking force reduction flag setting routine. Therefore, among the braking force reduction flag setting routines of FIG. 13, the same steps are assigned to the same processes as the braking force reduction flag setting routine of FIG. Hereinafter, the braking force reduction flag setting routine of FIG. 13 will be described focusing on the points different from the braking force reduction control routine of FIG.

When the braking force reduction flag setting routine of FIG. 13 is executed, the HVECU 70 first inputs the traveling mode Md and the vertical acceleration γ (step S200e). Here, the input method of the traveling mode Md has been described above. As the vertical acceleration γ, the one detected by the acceleration sensor 91 is input.

When the data is input in this way, it is determined whether the driving mode Md is the normal mode or the eco mode (step S210), and when it is determined that the driving mode Md is the normal mode (not the eco mode), the braking force reduction flag Fbr is set to a value. Set 0 (step S330) to end this routine.

When it is determined in step S210 that the driving mode Md is the eco mode, it is determined whether or not the vehicle is immediately after the accelerator off is started or immediately after the driving mode Md is switched (step S220), and immediately after the accelerator is off or in the driving mode Md. When it is determined that the switching has just been performed, the value 1 is set in the braking force reduction flag Fbr (step S320), and this routine is terminated.

When it is determined in step S220 that it is not immediately after the start of accelerator off and immediately after the switching of the traveling mode Md, the absolute value of the vertical acceleration γ is compared with the threshold value γref1 (step S230e). Here, the threshold value γref1 is a threshold value for determining whether or not to tentatively determine that the road is a bad road. When the absolute value of the vertical acceleration γ is larger than the threshold value γref1, it is tentatively determined that the road is bad, and the counter Ci is counted up by the value 1 (step S240e). On the other hand, when the absolute value of the vertical acceleration γ is equal to or less than the threshold value γref1, the tentative judgment is not made as a bad road (the tentative judgment is canceled when the tentative judgment is made), and the counter Ci is cleared (reset) to the value 0 (reset). Step S250e). Here, the product of the counter Ci and the execution interval of this routine means the duration for which it is tentatively determined to be a bad road.

Subsequently, the absolute value of the vertical acceleration γ is compared with the threshold value γref2 equal to or less than the threshold value γref1 (step S260e). Here, the threshold value γref2 is a threshold value for determining whether or not it is tentatively determined that the road is not a bad road. When the absolute value of the vertical acceleration γ is equal to or less than the threshold value γref2, it is tentatively determined that the road is not a bad road, and the counter Cj is counted up by the value 1 (step S270e). On the other hand, when the absolute value of the vertical acceleration γ is larger than the threshold value γref2, the tentative judgment is not made unless the road is bad (the tentative judgment is canceled when the tentative judgment is made), and the counter Cj is cleared (reset) to the value 0 (reset). Step S280e). Here, the product of the counter Cj and the execution interval of this routine means the duration for which it is tentatively determined that the road is not a bad road.

When the counter Ci and the counter Cj are set in this way, the counter Ci is compared with the threshold value Ciref (step S290e), and the counter Cj is compared with the threshold value Cjref (step S300e). Here, the threshold value Ciref is a threshold value for determining whether or not this determination (determination) is made as a bad road. The threshold value Cjref is a threshold value for determining whether or not this determination (determination) is made if the road is not a bad road. A uniform value (fixed value) was used for the threshold value Ciref and the threshold value Cjref.

In steps S290e and S300e, when the counter Ci is less than the threshold value Ciref and less than the counter Cjref, this determination (confirmation) is not performed regardless of whether the road is rough or not, and the braking force reduction flag set at the time of the previous execution of this routine is not performed. Check the value of (previous Fbr) (step S310). Then, when the previous braking force reduction flag (previous Fbr) is a value 1, the value 1 is set in the braking force reduction flag Fbr (step S320), and this routine is terminated. On the other hand, when the previous braking force reduction flag (previous Fbr) is a value 0, the value 0 is set in the braking force reduction flag Fbr (step S330), and this routine is terminated.

When the counter Ci is equal to or higher than the threshold value Ciref in step S290e, it is determined (determined) that the road is bad, the braking force reduction flag Fbr is set to a value 0 (step S330), and the routine is terminated. Therefore, when the braking force reduction flag Fbr reaches a value of 1 and the counter Ci reaches the threshold value Ciref or higher, the braking force reduction flag Fbr is switched to a value of 0. As a result, when the driving mode Md is in the eco mode (when the condition for reducing the braking force when the accelerator is off is satisfied), if it is determined that the road is rough during the execution of the braking force reduction control, the braking force is reduced. The execution of the control is stopped, and the required torque Td * is reduced (increased as the braking force). As a result, it is possible to suppress insufficient deceleration when the accelerator is off on a rough road, and it is possible to suppress deterioration of vehicle operability, as compared with the case where the braking torque is continued with a relatively small torque. can do.

When the counter Cj is equal to or higher than the threshold value Cjref in step S300e, it is determined (determined) that the road is not a bad road, a value 1 is set in the braking force reduction flag Fbr (step S320), and this routine is terminated. Therefore, when the braking force reduction flag Fbr reaches a value of 0 and the counter Cj reaches the threshold value Cjref or higher, the braking force reduction flag Fbr is switched to the value 1. As a result, when the driving mode Md is in the eco mode, when it is determined that the road is not a bad road when the braking force reduction control is not executed (when the execution is stopped (interrupted)), the braking force reduction control is executed. Is restarted to increase the required torque Td * (decrease the braking force). As a result, it is possible to respond to the intention of the driver who has turned on the eco switch 90.

In this modification, a uniform value (fixed value) is used for the threshold value Ciref and the threshold value Cjref. However, at least one of the threshold value Ciref and the threshold value Cjref may be set based on the vertical acceleration γ. When the threshold value Ciref and the threshold value Cjref are set based on the vertical acceleration γ, the relationship between the absolute value of the vertical acceleration γ and the threshold value Ciref and the threshold value Cjref is predetermined and stored in a ROM (not shown) as a map, and the vertical acceleration γ Given an absolute value, the corresponding thresholds Ciref and Cjref may be derived from this map. FIG. 14 shows an example of the relationship between the absolute value of the vertical acceleration γ and the threshold value Ciref and the threshold value Cjref. As shown in the figure, the threshold value Ciref is set so that when the absolute value of the vertical acceleration γ is large, it is smaller than when it is small. This is because when the braking force reduction flag Fbr is a value 1 (when braking force reduction control is being executed), the larger the absolute value of the vertical acceleration γ, the higher the possibility of a bad road. This is because it is preferable to switch the braking force reduction flag Fbr to a value of 0 (stop the braking force reduction control) at an early stage in order to further secure the vehicle operability when the accelerator is off on a rough road. Further, as shown in the figure, the threshold value Cjref is set so that when the absolute value of the vertical acceleration γ is small, it is smaller than when it is large. This is because when the braking force reduction flag Fbr is a value 0 (when the braking force reduction control is stopped), the smaller the absolute value of the vertical acceleration γ, the earlier the braking force reduction flag Fbr is switched to the value 1. This is because it is unlikely that vehicle operability will become a problem after that (even if braking force reduction control is restarted).

Further, in this modification, when the accelerator is off and the driving mode Md is the eco mode, the braking force reduction flag Fbr is set to a value when the counter Ci reaches the threshold value Ciref or more when the braking force reduction flag Fbr is a value 1. By switching to 0, the required torque Td * is reduced to the value Tdno (the value when the braking force reduction flag Fbr is 0) (the braking torque is increased). However, the braking force reduction flag Fbr is continued at a value 1, and the required torque Td * is set within a range larger than the value Tdno and smaller than the value Tdec (value when the braking force reduction flag Fbr is a value 1). When the absolute value of the vertical acceleration γ is large, it may be set to be smaller than when it is small.

Further, in this modification, when the accelerator is off and the traveling mode Md is the eco mode, the braking force reduction flag Fbr and the required torque Td * are set by using the counters Ci and Cj based on the absolute value of the vertical acceleration γ. did. However, instead of using the counters Ci and Cj, the required torque Td * may be set so that when the absolute value of the vertical acceleration γ is large, it becomes smaller (the braking torque becomes larger) than when it is small.

Next, a case where the braking force reduction flag Fbr and the required torque Td * are set by using the friction coefficient μ of the road surface when the accelerator is off and the traveling mode Md is the eco mode will be described. In this case, the accelerator off control routine of FIG. 2 is executed, and the braking force reduction flag setting routine of FIG. 15 is executed instead of the braking force reduction flag setting routine of FIG. The braking force reduction flag setting routine of FIG. 15 is shown in FIG. 4 except that the processing of steps S200f and S230f to 300f is executed instead of the processing of steps S200 and S230 to S300 of the braking force reduction flag setting routine of FIG. It is the same as the braking force reduction flag setting routine. Therefore, among the braking force reduction flag setting routines of FIG. 15, the same steps are assigned to the same processes as the braking force reduction flag setting routine of FIG. Hereinafter, the braking force reduction flag setting routine of FIG. 15 will be described focusing on the points different from the braking force reduction control routine of FIG.

When the braking force reduction flag setting routine of FIG. 15 is executed, the HVECU 70 first inputs the traveling mode Md and the friction coefficient μ of the road surface (step S200f). Here, the input method of the traveling mode Md has been described above. The coefficient of friction μ of the road surface is estimated based on the amount of raindrops Qr from the rain sensor 94 and is input.

When the data is input in this way, it is determined whether the driving mode Md is the normal mode or the eco mode (step S210), and when it is determined that the driving mode Md is the normal mode (not the eco mode), the braking force reduction flag Fbr is set to a value. Set 0 (step S330) to end this routine.

When it is determined in step S210 that the driving mode Md is the eco mode, it is determined whether or not the vehicle is immediately after the accelerator off is started or immediately after the driving mode Md is switched (step S220), and immediately after the accelerator is off or in the driving mode Md. When it is determined that the switching has just been performed, the value 1 is set in the braking force reduction flag Fbr (step S320), and this routine is terminated.

When it is determined in step S220 that it is not immediately after the start of accelerator off and immediately after the switching of the traveling mode Md, the friction coefficient μ of the road surface is compared with the threshold value μref1 (step S230f). Here, the threshold value μref1 is a threshold value for determining whether or not to tentatively determine that the path is a low mu path. Wet roads, snowy roads, icy roads, etc. can be considered as low mu roads. When the friction coefficient μ of the road surface is less than the threshold value μref1, it is tentatively determined that the road has a low mu road, and the counter Ck is counted up by a value of 1 (step S240f). On the other hand, when the friction coefficient μ of the road surface is equal to or higher than the threshold value μref1, the tentative determination is not made as a low mu road (the tentative determination is canceled when the tentative determination is made), and the counter Ck is cleared (reset) to a value of 0 (reset). Step S250f). Here, the product of the counter Ck and the execution interval of this routine means the duration for which it is tentatively determined that the path is low mu.

Subsequently, the friction coefficient μ of the road surface is compared with the threshold value μref2 having a threshold value μref1 or more (step S260f). Here, the threshold value μref2 is a threshold value for determining whether or not it is tentatively determined that the path is not a low mu path. When the friction coefficient μ of the road surface is equal to or greater than the threshold value μref2, it is tentatively determined that the road is not a low mu road, and the counter Cl is counted up by a value of 1 (step S270f). On the other hand, when the friction coefficient μ of the road surface is less than the threshold value μref2, the tentative determination is not made unless the road is a low mu road (the tentative determination is canceled when the tentative determination is made), and the counter Cl is cleared (reset) to the value 0 (step). S280f). Here, the product of the counter Cl and the execution interval of this routine means the duration for which it is tentatively determined that the path is not a low mu path.

When the counter Ck and the counter Cl are set in this way, the counter Ck is compared with the threshold Ckref (step S290f), and the counter Cl is compared with the threshold Clref (step S300f). Here, the threshold value Ckref is a threshold value for determining whether or not this determination (determination) is made as a low mu path. The threshold value Clref is a threshold value for determining whether or not this determination (determination) is made unless the path is low mu. A uniform value (fixed value) was used for the threshold value Ckref and the threshold value Clref.

When the counter Ck is less than the threshold value Ckref and less than the counter Clref in steps S290f and S300f, this determination (confirmation) is not performed regardless of whether the path is a low mu path or a low mu path, and the braking force set at the time of the previous execution of this routine is not performed. Check the value of the reduction flag (previous Fbr) (step S310). Then, when the previous braking force reduction flag (previous Fbr) is a value 1, the value 1 is set in the braking force reduction flag Fbr (step S320), and this routine is terminated. On the other hand, when the previous braking force reduction flag (previous Fbr) is a value 0, the value 0 is set in the braking force reduction flag Fbr (step S330), and this routine is terminated.

When the counter Ck is equal to or higher than the threshold value Ckref in step S290f, it is determined (determined) that the road is low mu, the braking force reduction flag Fbr is set to a value 0 (step S330), and the routine is terminated. Therefore, when the braking force reduction flag Fbr is a value 1 and the counter Ck reaches the threshold value Ckref or higher, the braking force reduction flag Fbr is switched to a value 0. As a result, when the driving mode Md is in the eco mode (when the condition for reducing the braking force when the accelerator is off is satisfied), if it is determined that the road is low mu during the execution of the braking force reduction control, the braking force is determined. The execution of the reduction control is stopped, and the required torque Td * is reduced (increased as the braking force). As a result, it is possible to suppress insufficient deceleration when the accelerator is off on a low mu road, and the vehicle operability is deteriorated, as compared with the case where the braking torque is continued with a relatively small torque. It can be suppressed.

When the counter Cl is equal to or higher than the threshold value Clref in step S300f, it is determined (determined) that the path is not a low mu path, the braking force reduction flag Fbr is set to a value 1 (step S320), and this routine is terminated. Therefore, when the braking force reduction flag Fbr reaches a value of 0 and the counter Cl reaches the threshold value Clref or higher, the braking force reduction flag Fbr is switched to the value 1. As a result, when the driving mode Md is in the eco mode, when the braking force reduction control is not executed (when the execution is stopped (interrupted)), it is determined that the road is not a low mu road, and the braking force reduction control is performed. The execution is restarted to increase the required torque Td * (decrease the braking force). As a result, it is possible to respond to the intention of the driver who has turned on the eco switch 90.

In this modification, a uniform value (fixed value) is used for the threshold Ckref and the threshold Clref. However, at least one of the threshold value Ckref and the threshold value Clref may be set based on the friction coefficient μ of the road surface. When the threshold Ckref and the threshold Clref are set based on the friction coefficient μ of the road surface, the relationship between the friction coefficient μ of the road surface and the threshold Ckref and the threshold Clref is stored in a ROM (not shown) as a map in advance, and the friction of the road surface is stored. Given the coefficient μ, the corresponding threshold Ckref and threshold Clref may be derived from this map. FIG. 16 shows an example of the relationship between the friction coefficient μ of the road surface and the threshold Ckref and the threshold Clref. As shown in the figure, the threshold value Ckref is set so that when the friction coefficient μ of the road surface is small, it is smaller than when it is large. This is because when the braking force reduction flag Fbr is a value 1 (when braking force reduction control is being executed), it is considered that the smaller the friction coefficient μ of the road surface, the higher the possibility of a low mu road. This is because it is preferable to switch the braking force reduction flag Fbr to a value of 0 (stop the braking force reduction control) at an early stage in order to further secure the vehicle operability when the accelerator is off on a low mu road. Further, as shown in the figure, the threshold value Clref is set to be smaller when the friction coefficient μ of the road surface is large than when it is small. This is because when the braking force reduction flag Fbr is 0 (when the braking force reduction control is stopped), the larger the friction coefficient μ of the road surface, the earlier the braking force reduction flag Fbr is switched to the value 1. This is because it is unlikely that vehicle operability will become a problem after that (even if the braking force reduction control is restarted).

Further, in this modification, when the accelerator is off and the driving mode Md is the eco mode, the braking force reduction flag Fbr is set to a value when the counter Ck reaches the threshold value Ckref or more when the braking force reduction flag Fbr is a value 1. By switching to 0, the required torque Td * is reduced to the value Tdno (the value when the braking force reduction flag Fbr is 0) (the braking torque is increased). However, the braking force reduction flag Fbr is continued at a value 1, and the required torque Td * is set within a range larger than the value Tdno and smaller than the value Tdec (value when the braking force reduction flag Fbr is a value 1). When the friction coefficient μ of the road surface is small, it may be set to be smaller than when it is large.

Further, in this modification, when the accelerator is off and the traveling mode Md is the eco mode, the braking force reduction flag Fbr and the required torque Td * are set by using the counters Ck and Cl based on the friction coefficient μ of the road surface. .. However, instead of using the counters Ck and Cl, the required torque Td * may be set so that when the friction coefficient μ of the road surface is small, it becomes smaller (the braking torque becomes larger) than when it is large.

In the embodiment and this modification, the HVECU 70 estimates the friction coefficient μ of the road surface based on the raindrop amount Qr from the rain sensor 94 so that the larger the raindrop amount Qr, the smaller the friction coefficient μ. However, the friction coefficient μ of the road surface may be estimated so as to decrease as the operating speed of the wiper increases, based on the operating speed of the wiper by the wiper operating device 96.

In the hybrid vehicle 20 of the embodiment, the engine ECU 24, the motor ECU 40, and the HVECU 70 are provided. However, the engine ECU 24, the motor ECU 40, and the HVECU 70 may be configured as a single electronic control unit.

In the hybrid vehicle 20 of the embodiment, the engine 22 and the motor MG1 are connected to the drive shaft 36 connected to the drive wheels 39a and 39b via the planetary gear 30, and the motor MG2 is connected to the drive shaft 36. However, as shown in the hybrid vehicle 120 of the modified example of FIG. 17, the motor MG is connected to the drive shaft 36 connected to the drive wheels 39a and 39b via the transmission 130, and the clutch 129 is connected to the rotation shaft of the motor MG. The engine 22 may be connected via the engine 22. Further, as shown in the electric vehicle 220 of the modified example of FIG. 18, the electric vehicle may be configured such that the motor MG for traveling is connected to the drive shaft 36 connected to the drive wheels 39a and 39b. That is, any configuration may be used as long as it includes a motor for traveling.

The correspondence between the main elements of the examples and the main elements of the invention described in the column of means for solving the problem will be described. In the embodiment, the motor MG2 corresponds to the "motor", the battery 50 corresponds to the "battery", and the HVECU 70 and the motor ECU 40 execute the accelerator off control routine of FIG. 2 and the braking force reduction flag setting routine of FIG. Corresponds to the "control device".

As for the correspondence between the main elements of the examples and the main elements of the invention described in the column of means for solving the problem, the invention described in the column of means for solving the problem in the examples is carried out. Since it is an example for specifically explaining the form for solving the problem, the elements of the invention described in the column of means for solving the problem are not limited. That is, the interpretation of the invention described in the column of means for solving the problem should be performed based on the description in the column, and the examples are the inventions described in the column of means for solving the problem. It is just a concrete example.

Although the embodiments for carrying out the present invention have been described above with reference to examples, the present invention is not limited to these examples, and various embodiments are used without departing from the gist of the present invention. Of course, it can be done.

The present invention can be used in the automobile manufacturing industry and the like.

20,120 Hybrid vehicle, 22 engine, 23 crank position sensor, 24 engine electronic control unit (engine ECU), 26 crank shaft, 28 damper, 30 planetary gear, 36 drive shaft, 38 differential gear, 39a, 39b drive wheel, 40 Electronic control unit for motor (motor ECU), 41,42 inverter, 43,44 rotation position sensor, 50 battery, 51a voltage sensor, 51b current sensor, 51c temperature sensor, 52 electronic control unit for battery (battery ECU), 54 power Line, 70 Hybrid Electronic Control Unit (HVECU), 80 Ignition Switch, 81 Shift Lever, 82 Shift Position Sensor, 83 Accelerator Pedal, 84 Accelerator Pedal Position Sensor, 85 Brake Pedal, 86 Brake Pedal Position Sensor, 88 Vehicle Speed Sensor, 90 Eco switch, 91 acceleration sensor, 92 yaw rate sensor, 93 gradient sensor, 94 rain sensor, 96 wiper activator, 129 clutch, 130 transmission, 220 electric vehicle, MG, MG1, MG2 motor.

Claims (1)

With a motor for running
A battery that exchanges power with the motor,
A control device that controls the motor so that braking force acts on the vehicle when the accelerator is off.
It is a car equipped with
When the accelerator is off, when the braking force reduction condition is satisfied, the control device accelerates the vehicle in the front-rear direction within a range equal to or less than the braking force when the reduction condition is not satisfied. The braking force is changed based on at least one of the lateral acceleration of the vehicle, the vertical acceleration of the vehicle, the yaw rate, the road surface gradient, and the friction coefficient of the road surface .
Further, the control device is in the front-rear direction of the vehicle when the braking force is reduced as compared with the case where the reduction condition is satisfied and the reduction condition is not satisfied when the accelerator is off. When the state in which the acceleration is larger than the predetermined acceleration continues for a predetermined time, the braking force is increased.
Car.

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