JP5685164B2 - Brake control device for vehicle - Google Patents

Description

  The present invention relates to a braking control device for a vehicle that performs braking control during turning to apply a braking force to wheels on the inner side in the turning direction when the vehicle turns.

  Conventionally, for example, a control device described in Patent Document 1 has been proposed as a vehicle braking control device that performs braking control to reduce the turning radius when the vehicle turns. This braking control device is provided for rearward inward of the turning direction of the vehicle when the absolute value of the steering angle detected when the switch mounted on the vehicle is on is greater than or equal to a predetermined steering angle determination value. A braking control during turning (also referred to as “small turning control”) for applying a braking force to the wheel (right rear wheel when turning right) is performed.

  In a vehicle that turns in a state where the small turn control is performed in this manner, compared with a vehicle that does not perform the small turn control when turning, the vehicle turns with a motion that rotates around the rear wheel inside the turning direction of the vehicle. The turning radius becomes small, that is, a small turn is effective.

  By the way, in recent years, development of a general passenger car equipped with a braking control device capable of executing a small turning control has been advanced. In such a general passenger car (hereinafter simply referred to as “vehicle”), for example, when an obstacle is found in the traveling direction of the vehicle by the driver, the absolute value of the steering angle is increased by the steering of the steering by the driver. Become. When the steering angle of the steering becomes equal to or larger than the steering angle determination value and the vehicle body speed of the vehicle becomes less than the vehicle body speed determination value (for example, 10 km / h), the small turn control is started. As a result, the vehicle can avoid the obstacle with a margin as much as the turning is effective as compared with the case where the vehicle turns without performing the turning control.

  The small turning control is terminated when at least one of the steering angle of the steering is less than the steering angle determination value and the vehicle body speed of the vehicle is equal to or higher than the vehicle body speed determination value is established. At the end of the small turning control, the reduction control is performed to reduce the braking force applied to the rear wheel inside the turning direction of the vehicle. Note that the braking force decreasing speed at the time of execution of the decreasing control is set to a constant speed regardless of the traveling state of the vehicle at that time (for example, the steering angle of the steering wheel or the vehicle body speed).

JP-A-8-207823

  By the way, a force (also referred to as “centrifugal force”) to the outside of the turning direction is acting on the turning vehicle. This outward force in the turning direction varies depending on the traveling state of the vehicle. For example, when the absolute value of the steering angle of the steering is large, the force to the outside in the turning direction becomes larger than when the absolute value of the steering angle is small.

  For this reason, in the case where the decrease control is performed in accordance with the establishment of the end condition of the small turning control, when the absolute value of the steering angle is large, an understeer tendency tends to occur more than when the absolute value of the steering angle is small. This is because the braking force applied to the rear wheels on the inner side in the turning direction, which is also a force opposite to the force on the outer side in the turning direction applied to the vehicle, is rapidly reduced by the reduction control. If the vehicle suddenly shows an understeer tendency, the vehicle occupant may feel a sense of jumping outward in the turning direction. Therefore, in the conventional small turning control, there is room for improvement in the method of reducing the braking force with respect to the rear wheel inside the turning direction after the end condition of the small turning control is satisfied.

  The present invention has been made in view of such circumstances. The purpose is to reduce the feeling of jumping outward in the turning direction that is felt by the vehicle occupant when the braking force is reduced in accordance with the completion of the braking control termination condition for applying braking force to the wheels on the inner side in the turning direction. An object of the present invention is to provide a braking control device for a vehicle that can be used.

  In order to achieve the above object, the present invention performs a braking control during turning that applies a braking force (BP) to a wheel on the inner side in the turning direction when the vehicle turns, and then the condition for ending the braking control during turning is satisfied. In this case, in the vehicle braking control device that performs the reduction control to reduce the braking force (BP) to the wheels on the inner side in the turning direction, the steering angle related information (A) that fluctuates as the steering angle of the steering (30) changes. The steering angle related information acquisition means (51, S11, S31) to be acquired and the steering angle related information (A) acquired by the steering angle related information acquisition means (51, S11, S31) when performing the reduction control. On the basis of the control means (51, S21, S3), the slower the braking force (BP) decrease rate (Vb) applied to the wheels on the inner side in the turning direction becomes, the greater the force on the outside in the turning direction applied to the vehicle. ) And, and summarized in that comprises a.

  According to the above configuration, when the termination condition of the braking control during turning is satisfied and the reduction control is performed, the force on the outside in the turning direction applied to the vehicle is estimated based on the acquired steering angle related information. And reduction control is performed so that the decreasing speed of the braking force with respect to the wheel inside a turning direction becomes low, so that the force to the outside of the turning direction added to a vehicle is large. That is, as the force toward the outside in the turning direction increases, the braking force applied to the wheel inside the turning direction, which is the force opposite to the force toward the outside in the turning direction, is gradually reduced. Therefore, compared to the conventional case in which the reduction speed is set to a constant value regardless of the magnitude of the force in the outward direction of the turning direction, the force opposite to the force in the outward direction of the turning direction does not decrease abruptly. When the vehicle turns with execution, the vehicle is less likely to be understeered, or the vehicle is gently understeered. Therefore, when the reduction control is performed in accordance with the establishment of the termination condition of the turning braking control, it is possible to reduce the feeling of jumping outward in the turning direction which is felt by the vehicle occupant.

  The vehicle braking control apparatus according to the present invention is based on the steering angle related information (A) acquired by the steering angle related information acquisition means (51, S11, S31), and is the force applied to the vehicle outward in the turning direction large? Steering angle related information determining means (51, S14) for determining whether or not, the control means (51, S21) is outward in the turning direction applied to the vehicle by the steering angle related information determining means (51, S14). In the case where it is determined that the force of the braking force (BP) is large, the braking force (BP) decreasing speed with respect to the wheel on the inner side in the turning direction is compared with the case where it is determined that the force applied to the vehicle to the outside in the turning direction is small. It is preferable to slow down (Vb).

  According to the above configuration, it is determined based on the acquired steering angle related information whether or not the force applied to the vehicle outward in the turning direction is large. When the braking force decreasing speed for the wheels on the inner side in the turning direction during the reduction control is determined that the force toward the outside in the turning direction is large, the force at the outside in the turning direction is determined to be small Is set to a lower speed. Therefore, when it is determined that the force applied to the vehicle on the outside in the turning direction is large, the vehicle is less prone to understeer, or the vehicle is moderately slowed by the decrease in braking force applied to the wheels on the inside in the turning direction. It tends to understeer. As a result, it is possible to reduce the feeling of jumping outward in the turning direction, which is felt by the vehicle occupant when the vehicle turns with reduction control.

  The vehicle braking control apparatus of the present invention further includes vehicle speed related information acquisition means (51, S12, S15, S32) for acquiring vehicle speed related information (VS, Ac) related to the vehicle body speed of the vehicle, and the control means ( 51, S21, S35) is a turning direction applied to the vehicle based on the vehicle speed related information (VS, Ac) acquired by the vehicle speed related information acquisition means (51, S12, S15, S32) when performing the decrease control. It is preferable that the decreasing speed (Vb) of the braking force (BP) with respect to the wheel on the inner side in the turning direction is slower as the outward force is larger.

  According to the above configuration, when the termination condition of the braking control during turning is satisfied and the reduction control is performed, the force on the outside in the turning direction applied to the vehicle is estimated based on the acquired vehicle speed related information. And reduction control is performed so that the decreasing speed of the braking force with respect to the wheel inside a turning direction becomes low, so that the force to the outside of the turning direction added to a vehicle is large. Therefore, at the time of turning of the vehicle accompanied by execution of the reduction control, the vehicle is less likely to be understeered because the braking force decreasing speed for the wheels on the inner side in the turning direction is set based on the steering angle related information and the vehicle speed related information. Slowly understeer. Therefore, it is possible to reduce the feeling of jumping outward in the turning direction, which is felt by the vehicle occupant when the vehicle turns with reduction control.

  The vehicle braking control device according to the present invention has a force applied to the vehicle outward in the turning direction based on the vehicle speed related information (VS, Ac) acquired by the vehicle speed related information acquisition means (51, S12, S15, S32). The vehicle speed related information determining means (51, S16, S17) for determining whether or not the vehicle speed is larger is further provided, and the control means (51, S21) is a vehicle by the vehicle speed related information determining means (51, S12, S15, S32). When it is determined that the force on the outside in the turning direction applied to the vehicle is large, the braking force on the wheels on the inside in the turning direction is compared with the case where the force on the outside in the turning direction applied to the vehicle is determined to be small. It is preferable to decrease the decrease rate (Vb) of (BP).

  According to the above configuration, it is determined based on the acquired vehicle speed related information whether or not the force applied to the vehicle outward in the turning direction is large. When the braking force decreasing speed for the wheels on the inner side in the turning direction during the reduction control is determined that the force toward the outside in the turning direction is large, the force at the outside in the turning direction is determined to be small Is set to a lower speed. Therefore, when it is determined that the force applied to the vehicle on the outside in the turning direction is large, the vehicle is less prone to understeer, or the vehicle is moderately slowed by the decrease in braking force applied to the wheels on the inside in the turning direction. It tends to understeer. As a result, it is possible to reduce the feeling of jumping outward in the turning direction, which is felt by the vehicle occupant when the vehicle turns with reduction control.

  In order to explain the present invention in an easy-to-understand manner, it has been described in association with the reference numerals of the drawings showing the embodiments, but it goes without saying that the present invention is not limited to the embodiments.

The block diagram which shows an example of the vehicle carrying the ECU for brakes which is one Embodiment of the braking control apparatus of this invention. 6 is a flowchart for explaining a small turn control end processing routine in the first embodiment; The timing chart which shows a mode that the steering angle of a steering wheel, the vehicle body speed of a vehicle, the operation aspect of an accelerator pedal, and the braking force with respect to a control object wheel change in 1st Embodiment. The timing chart which shows a mode that the steering angle of a steering wheel, the vehicle body speed of a vehicle, the operation aspect of an accelerator pedal, and the braking force with respect to a control object wheel change in 1st Embodiment. The timing chart which shows a mode that the steering angle of a steering wheel, the vehicle body speed of a vehicle, the operation aspect of an accelerator pedal, and the braking force with respect to a control object wheel change in 1st Embodiment. 9 is a flowchart for explaining a small turn control end processing routine in the second embodiment.

(First embodiment)
Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS. In the following description of the present specification, the traveling direction (forward direction) of the vehicle is assumed to be the front (front of the vehicle).

  As shown in FIG. 1, the vehicle according to the present embodiment includes a plurality of (four in the present embodiment) wheels (right front wheel FR, left front wheel FL, right rear wheel RR, and left rear wheel RL). The FL functions as a drive wheel (a so-called front wheel drive vehicle). Such a vehicle includes a driving force generation device 11 for driving the vehicle, a steering device 12 for turning the front wheels FR and FL as steered wheels (steering wheels), and the wheels FL, FR, RL, and RR. And a braking device 13 for applying a braking force. Further, the vehicle is provided with a control device 15 for controlling the devices 11 to 13.

  The driving force generator 11 includes an engine 21 that generates a driving force based on an operation amount of the accelerator pedal 20 by the driver, that is, an accelerator opening (accelerator operation amount), and an automatic connected to the output shaft of the engine 21. A transmission 22 is provided. Further, the driving force generator 11 is provided with an accelerator opening sensor SE1 that outputs a detection signal corresponding to the accelerator opening to the control device 15. When the engine 21 is driven, the driving force output from the automatic transmission 22 is distributed to the front wheels FR and FL via the differential gear 23, so that the vehicle moves forward or backward.

  The steering device 12 is provided with a steering shaft 31 to which a steering 30 that is steered (operated) by a driver is fixed, and a steering actuator 32 that is connected to the steering shaft 31. Further, the steering device 12 is provided with a link mechanism portion 33 including a tie rod that can be moved in the left-right direction of the vehicle by a steering actuator 32 and a link that steers the front wheels FL and FR by the movement of the tie rod. Yes. The steering device 12 is provided with a steering angle sensor SE2 that outputs a detection signal corresponding to the steering angle of the steering 30 to the control device 15.

  The braking device 13 includes a hydraulic pressure generating device 41 that generates a brake hydraulic pressure corresponding to the operating force of the brake pedal 40 by the driver, and a plurality of (this embodiment) provided individually for each of the wheels FR, FL, RR, and RL. There are four brake cylinders 43 connected to the wheel cylinders 42a, 42b, 42c, 42d. In addition, the brake device 13 is provided with a brake switch SW1 that outputs a detection signal to the control device 15 according to the operation state (on or off) of the brake pedal 40 by the driver.

  The brake actuator 43 is configured to apply a braking force to the wheels FR, FL, RR, RL even when the driver does not operate the brake pedal 40. For example, the brake actuator 43 is a differential pressure regulating valve (not shown) for generating a differential pressure between the brake hydraulic pressure on the hydraulic pressure generating device 41 side and the brake hydraulic pressure in the wheel cylinders 42a, 42b, 42c, 42d. And an electric pump (not shown) for supplying brake fluid pressure into the wheel cylinders 42a, 42b, 42c, 42d. The brake actuator 43 is provided with various valves for individually adjusting the brake fluid pressure in the wheel cylinders 42a, 42b, 42c, and 42d. That is, the brake actuator 43 of this embodiment can adjust the braking force with respect to each wheel FR, FL, RR, RL individually.

  In addition to the accelerator opening sensor SE1, the steering angle sensor SE2, and the brake switch SW1, the control device 15 includes wheel speed sensors SE3, SE4, SE5, SE6 for detecting the wheel speeds of the wheels FR, FL, RR, RL. And an acceleration sensor (also referred to as “G sensor”) SE7 for detecting acceleration in the longitudinal direction of the vehicle is electrically connected. The control device 15 includes a plurality of ECUs (also referred to as “electronic control devices”) including a CPU, a ROM, a RAM, and the like. For example, the control device 15 includes an engine ECU 50 for controlling the driving force generation device 11 and a brake ECU 51 as a braking control device for controlling the braking device 13. These ECUs 50 and 51 can transmit and receive various types of information.

  The brake ECU 51 of the present embodiment performs small turn control (braking control during turning) for reducing the turning radius of the vehicle when the vehicle turns. Specifically, the brake ECU 51 determines the absolute value of the steering angle of the steering wheel 30 when the operation button 55 as an operation unit operated by the driver to permit / prohibit the execution of the small turn control is on. Is greater than or equal to the steering angle determination value and the vehicle body speed of the vehicle is less than the vehicle speed determination value (for example, 10 km / h), the small turning control is performed. At this time, the brake ECU 51 controls the brake actuator 43 so that the braking force is applied to the rear wheel on the inner side in the turning direction of the vehicle (the right rear wheel when turning in the right direction). Therefore, in the present embodiment, the brake ECU 51 also functions as a control unit.

  Then, the vehicle for which the small turn control is performed turns with a motion that rotates around the rear wheel inside the turning direction of the vehicle. As a result, the turning radius of the vehicle becomes smaller compared to the case where the turning control is not performed.

  After that, when the end condition of the small turn control is satisfied, the reduction control is performed to reduce the wheel cylinder pressure of the wheel cylinder corresponding to the rear wheel inside the turning direction in order to reduce the braking force against the rear wheel inside the turning direction of the vehicle. Is called. Here, when the vehicle turns, a force outward in the turning direction (also referred to as “centrifugal force”) acts on the vehicle. During execution of the small turn control, the braking force applied to the rear wheel on the inner side in the turning direction becomes a force opposite to the force on the outer side in the turning direction applied to the vehicle. For this reason, the vehicle occupant is less likely to feel a sense of jumping outward in the turning direction because the braking force is applied to the rear wheel in the turning direction.

  However, when the reduction control is started, the braking force with respect to the rear wheel inside the turning direction of the vehicle is reduced. That is, the force that opposes the outward force in the turning direction applied to the vehicle is reduced. For this reason, if the braking force applied to the rear wheels inside the turning direction is suddenly reduced in a state where the force applied to the outside of the turning direction applied to the vehicle is large, the vehicle suddenly shows an understeer tendency and the turning felt by the vehicle occupant The feeling of jumping outward in the direction suddenly increases. As a result, there is a risk of discomfort for the vehicle occupant. In order to solve such a problem, it is necessary to devise a mode of reducing the braking force applied to the rear wheel in the turning direction during the reduction control.

  Therefore, in the brake ECU 51 of the present embodiment, the braking force decreasing speed for the rear wheels inside the turning direction is set based on the steering angle of the steering 30, the vehicle body speed and the accelerator opening, and the set decreasing speed is set. A small turn control end processing routine for performing the decrease control based on the control is executed. The reason for setting the reduction speed based on the above three parameters is that the greater the absolute value of the steering angle of the steering wheel 30, the greater the force applied to the vehicle in the turning direction, and the higher the vehicle body speed. This is because the outward force in the turning direction applied to the vehicle increases.

  Next, the small turning control end processing routine of the present embodiment will be described with reference to the flowchart shown in FIG. In this embodiment, “under turning control” means that the end condition of the small turning control is satisfied after the start of the condition for starting the small turning control and the increase of the braking force for the rear wheel in the turning direction is started. It means until the decrease control started at the end.

  Now, the small turning control end processing routine is executed at predetermined intervals set in advance while the operation button 55 is in the ON state. In the small turning control end processing routine, the brake ECU 51 determines whether or not the small turning control flag FLG is ON (step S10). The small turn control flag FLG is a flag that is turned on when the start condition of the small turn control is satisfied, and is kept on during the small turn control. When the small turn control flag FLG is OFF (step S10: NO), the brake ECU 51 temporarily ends the small turn control end processing routine because the small turn control is not being performed.

  On the other hand, when the small turn control flag FLG is on (step S10: YES), the brake ECU 51 acquires the steering angle A of the steering wheel 30 as steering angle related information based on the detection signal from the steering angle sensor SE2 (step S10). S11). Therefore, in the present embodiment, the brake ECU 51 also functions as a steering angle related information acquisition unit that acquires the steering angle A as the steering angle related information that varies as the steering angle of the steering wheel 30 changes.

  Subsequently, the brake ECU 51 uses the wheel speed sensors SE3 to SE6 to acquire the vehicle body speed VS of the vehicle as vehicle speed related information (step S12). That is, the brake ECU 51 calculates the wheel speeds of the wheels FR, FL, RR, and RL based on the detection signals from the wheel speed sensors SE3 to SE6. Then, the brake ECU 51 acquires the vehicle body speed VS based on the wheel speed of at least one of the calculated wheel speeds of the wheels FR, FL, RR, and RL. Therefore, in the present embodiment, the brake ECU 51 also functions as vehicle speed related information acquisition means for acquiring the vehicle body speed VS as vehicle speed related information related to the vehicle body speed of the vehicle.

Then, the brake ECU 51 determines whether or not an end condition for the small turn control is satisfied (step S13). In the present embodiment, when at least one of the following two conditions is satisfied, it is determined that the end condition for the small turn control is satisfied. Note that the steering angle determination value Ath1 and the vehicle speed determination value VSth1 are determination values set as determination criteria for determining whether or not the end condition of the small turn control is satisfied.
(First condition) The absolute value of the steering angle A of the steering wheel 30 acquired in step S11 is less than the steering angle determination value Ath1.
(Second condition) The vehicle body speed VS acquired in step S12 exceeds the vehicle speed determination value VSth1 (for example, 10 km / h).

  When both the first and second conditions are not satisfied (step S13: NO), the brake ECU 51 temporarily ends the small-turn control end processing routine because the small-turn control end condition is not satisfied. On the other hand, when at least one of the first and second conditions is satisfied (step S13: YES), the brake ECU 51 determines the steering angle A of the steering wheel 30 acquired in step S11 because the end condition for the small turn control is satisfied. It is estimated that the greater the absolute value of is, the greater the force applied to the vehicle is in the turning direction. Then, the brake ECU 51 determines whether or not the absolute value of the acquired steering angle A is equal to or larger than a reference steering angle Ath2 preset to a value smaller than the steering angle determination value Ath1 (step S14). The reference steering angle Ath2 is a value set as a criterion for determining whether or not the force applied to the vehicle on the outside in the turning direction is large. In the present embodiment, the reference steering angle Ath2 is used not only as a criterion for determining whether or not the force toward the outside in the turning direction is large, but also as a criterion for determining whether or not the driver is willing to go straight ahead. .

  When the absolute value of the steering angle A is less than the reference steering angle Ath2 (step S14: NO), the brake ECU 51 has a small force applied to the vehicle in the turning direction and the driver is willing to move the vehicle straight. Judgment is made, and the process proceeds to step S20 described later. On the other hand, when the absolute value of the steering angle A is greater than or equal to the reference steering angle Ath2 (step S14: YES), it is determined that the force applied to the vehicle outward in the turning direction is large and the driver does not intend to go straight ahead. The process proceeds to the next step S15. Therefore, in the present embodiment, the brake ECU 51 determines whether or not the force to the outside in the turning direction applied to the vehicle is large based on the steering angle A of the steering wheel 30 acquired when the end condition of the small turn control is satisfied. It also functions as a steering angle related information determining means.

  In step S15, the brake ECU 51 acquires the accelerator opening (accelerator operation amount) Ac based on the detection signal from the accelerator opening sensor SE1. The vehicle body speed VS tends to be higher as the accelerator opening degree Ac is larger. That is, the accelerator opening degree Ac is an example of vehicle speed related information related to the vehicle body speed of the vehicle. Therefore, in the present embodiment, the brake ECU 51 also functions as vehicle speed related information acquisition means.

  Subsequently, the brake ECU 51 estimates that the greater the acquired accelerator opening Ac, the greater the force on the outside in the turning direction applied to the vehicle. Then, the brake ECU 51 determines whether or not the accelerator opening degree Ac is equal to or greater than a reference opening degree (reference operation amount) Acth set as a criterion for determining whether or not the force to the outside in the turning direction applied to the vehicle is large. Determination is made (step S16). The reference opening degree Acth of the present embodiment is also a determination criterion for determining whether or not the driver is operating the accelerator pedal 20, that is, whether or not the accelerator is on. When the accelerator opening degree Ac is less than the reference opening degree Acth (step S16: NO), the brake ECU 51 determines that the accelerator force is not on and the force applied to the vehicle outside in the turning direction is small, and the processing is performed. The process proceeds to step S20 described later. On the other hand, when the accelerator opening degree Ac is equal to or larger than the reference opening degree Acth (step S16: YES), the brake ECU 51 determines that the accelerator is on and the force to the outside in the turning direction applied to the vehicle is large. Next step S17 is entered. Therefore, in the present embodiment, the brake ECU 51 determines whether or not the force applied to the vehicle outward in the turning direction is large based on the accelerator opening degree Ac acquired when the condition for terminating the braking control during turning is satisfied. It also functions as vehicle speed related information determination means.

  The brake ECU 51 estimates that the higher the vehicle body speed VS acquired in step S12, the greater the force applied to the vehicle in the turning direction. In step S17, the brake ECU 51 determines whether or not the acquired vehicle body speed VS is equal to or higher than a reference vehicle speed VSth2 set as a determination criterion for determining whether or not the vehicle body speed is high. When the vehicle body speed VS is equal to or higher than the reference vehicle speed VSth2 (step S17: YES), the brake ECU 51 has a greater force toward the outside in the turning direction applied to the vehicle than when the vehicle body speed VS is less than the reference vehicle speed VSth2. Judgment is made, and the process proceeds to the next step S18. On the other hand, when the vehicle body speed VS is lower than the reference vehicle speed VSth2 (step S17: NO), the brake ECU 51 has a force applied to the vehicle outside in the turning direction compared to the case where the vehicle body speed VS is equal to or higher than the reference vehicle speed VSth2. The process is determined to be small, and the process proceeds to step S19 described later. Therefore, in the present embodiment, the brake ECU 51 determines whether or not the force applied to the vehicle outward in the turning direction is large based on the vehicle body speed VS acquired when the turning braking control termination condition is satisfied. It also functions as vehicle speed related information determination means.

  In step S18, the brake ECU 51 sets the braking force decreasing speed Vb for the rear wheel on the inner side in the turning direction to the first speed PV1. Thereafter, the brake ECU 51 proceeds to step S21, which will be described later.

  In step S19, the brake ECU 51 sets the braking force decreasing speed Vb for the rear wheel inside the turning direction to the second speed PV2 higher than the first speed PV1. Thereafter, the brake ECU 51 proceeds to step S21, which will be described later.

  In step S20, the brake ECU 51 sets the braking force decreasing speed Vb for the rear wheels on the inner side in the turning direction to a third speed PV3 that is higher than the second speed PV2. Thereafter, the brake ECU 51 shifts the process to the next step S21. The third speed PV3 is a speed at which the braking force BP is reduced or close to the speed by the conventional reduction control.

  In step S21, the brake ECU 51 corresponds to the rear wheel in the turning direction so that the braking force to the rear wheel in the turning direction is reduced at the decreasing speed Vb set in any step of steps S18 to S20. Reduction control is performed to reduce the wheel cylinder pressure of the wheel cylinder. Subsequently, the brake ECU 51 determines whether or not the decrease control is finished (step S22). As this determination method, whether or not the current value supplied to each valve (linear electromagnetic valve) that has been operated to apply a braking force to the rear wheel inside the turning direction has become “0 (zero)”. The method etc. which judge are mentioned.

  If the decrease control has not yet been completed (step S22: NO), the brake ECU 51 once ends the small turn control end processing routine. On the other hand, when the reduction control is completed (step S22: YES), the brake ECU 51 sets the small turning control flag FLG to off (step S23), and then temporarily terminates the small turning control end processing routine.

  Next, the operation of the vehicle after the end condition of the small turn control is established will be described with reference to timing charts shown in FIGS. 3, 4, and 5. As a premise, it is assumed that the operation button 55 is maintained in the on state.

  First, the braking force BP for the rear wheel (hereinafter also referred to as “control target wheel”) in the turning direction is accelerated by the acceleration of the vehicle in a situation where the decrease control is performed in accordance with the establishment of the end condition of the small turning control. A case where the decrease speed Vb is changed will be described with reference to a timing chart shown in FIG.

  As shown in FIG. 3, at the first timing t11, even if the accelerator pedal 20 is on, the absolute value of the steering angle A of the steering wheel 30 is not less than the steering angle determination value Ath1 and the vehicle body speed of the vehicle. Since VS is equal to or less than the vehicle speed determination value VSth1, the end condition for the small turn control is not satisfied. That is, the braking force BP for the control target wheel is held. When the absolute value of the steering angle A of the steering wheel 30 becomes less than the steering angle determination value Ath1 at the second timing t12 thereafter, the end condition for the small turn control is satisfied. Then, the decrease speed Vb is set to a value based on the steering angle A, the vehicle body speed VS, and the accelerator opening degree Ac at that time.

  In this case, the absolute value of the steering angle A of the steering wheel 30 is greater than or equal to the reference steering angle Ath2, the accelerator pedal 20 is on, and the vehicle body speed VS is less than the reference vehicle speed VSth2. The outward force is moderate. Therefore, the decreasing speed Vb of the braking force BP is set to the second speed PV2. Then, after the second timing t12, the braking force BP for the wheel to be controlled is decreased at a medium speed.

  The force opposite to the outward force in the turning direction applied to the vehicle (that is, the braking force BP for the wheel to be controlled) is gradually reduced as compared with the case where the reduction speed Vb is set to the third speed PV3. As a result, the vehicle is less prone to understeer because the decrease speed Vb is set to a low speed, or the vehicle is gently understeered. Therefore, when the vehicle turns with the execution of the reduction control, the feeling of jumping outward in the turning direction felt by the vehicle occupant is reduced.

  Then, when the vehicle body speed VS becomes equal to or higher than the reference vehicle speed VSth2 at the third timing t13, the force applied to the vehicle outward in the turning direction increases, so the decrease speed Vb of the braking force BP is increased from the second speed PV2. 1 speed is changed to PV1. As a result, the braking force BP for the wheel to be controlled is more gradually reduced as compared with the case where the decrease speed Vb is maintained at the second speed PV2. Therefore, even if the force to the outside of the turning direction applied to the vehicle increases, the vehicle is less likely to be understeered, or the vehicle is gently understeered. As a result, the vehicle occupant is unlikely to feel a sense of jumping outward in the turning direction. Thereafter, when the braking force BP for the target wheel becomes “0 (zero)” at the fourth timing t14, the reduction control, that is, the small turning control is finished.

  Next, a case where the accelerator pedal 20 is off at the time when the end condition of the small turn control is satisfied, and then the accelerator pedal 20 is turned on after the decrease control is started and the vehicle body speed VS becomes equal to or higher than the reference vehicle speed VSth2. This will be described with reference to the timing chart shown in FIG.

  Now, as shown in FIG. 4, when the absolute value of the steering angle A of the steering wheel 30 becomes less than the steering angle determination value Ath1 at the first timing t21, the condition for ending the small turning control is satisfied, and therefore the reduction control is started. . At the first timing t21, the accelerator pedal 20 is off, the vehicle body speed VS is less than the reference vehicle speed VSth2, and the absolute value of the steering angle A is greater than or equal to the reference steering angle Ath2. Therefore, at this time, it is determined that the force to the outside in the turning direction applied to the vehicle is small, and the decrease speed Vb is set to the third speed PV3 that is the highest speed among the speeds PV1, PV2, and PV3. Then, the braking force BP for the control target wheel is rapidly reduced.

  When the accelerator pedal 20 is turned on at the second timing t22 during the decrease control, it is determined that the outward force in the turning direction applied to the vehicle will increase from now on, and the decrease speed Vb is changed. At the second timing t22, since the vehicle body speed VS is less than the reference vehicle speed VSth2, the decrease speed Vb is changed from the third speed PV3 to the second speed PV2. Therefore, even if the accelerator pedal 20 is turned on, the vehicle is less prone to understeer as the reduction speed Vb is set to a lower speed than when the reduction speed Vb is maintained at the third speed PV3, or Vehicles tend to understeer slowly. That is, it is difficult for the vehicle occupant to feel a sense of jumping outward in the turning direction.

  When the vehicle body speed VS becomes equal to or higher than the reference vehicle speed VSth2 at the third timing t23 thereafter, it is determined that the force applied to the vehicle outward in the turning direction is further increased, and the decrease speed Vb is changed from the second speed PV2 to the first speed PV1. Changed to Therefore, even when the vehicle body speed VS becomes equal to or higher than the reference vehicle speed VSth2, the vehicle is understeered as much as the braking force BP for the control target wheel is gradually reduced as compared with the case where the reduced speed Vb is maintained at the second speed PV2. Less prone to trend, or vehicles tend to understeer slowly. That is, even when the vehicle body speed VS of the vehicle becomes high and the force toward the outside in the turning direction increases, the vehicle occupant hardly feels a sense of jumping out to the outside in the turning direction. Thereafter, when the braking force BP for the target wheel becomes “0 (zero)” at the fourth timing t24, the reduction control, that is, the small turn control is finished.

  Next, the accelerator pedal 20 is turned on before the end condition of the small turn control is satisfied, and thereafter, after the decrease control is started, the vehicle body speed VS becomes equal to or higher than the reference speed VSth2, and after that, the steering angle A of the steering wheel 30 is increased. Will be described with reference to the timing chart shown in FIG. Here, the vehicle speed determination value VSth1 is assumed to be the same value as the reference vehicle speed VSth2.

  As shown in FIG. 5, at the first timing t31, even if the accelerator pedal 20 is turned on, the absolute value of the steering angle A of the steering wheel 30 is not less than the steering angle determination value Ath1, and the vehicle body speed of the vehicle. VS is less than or equal to vehicle speed determination value VSth1. That is, at the first timing t31, since the end condition for the small turn control is not satisfied, the decrease control is not started. At the subsequent second timing t32, the vehicle body speed VS of the vehicle exceeds the vehicle speed determination value VSth1, so the end condition for the small turn control is satisfied, and the decrease control is started.

  At the second timing t32, the accelerator pedal 20 is on, the vehicle body speed VS exceeds the reference vehicle speed VSth2 (= VSth1), and the absolute value of the steering angle A is greater than or equal to the reference steering angle Ath2. As a result, since it is determined that the force on the outside in the turning direction applied to the vehicle is large, the decreasing speed Vb is set to the first speed PV1 that is the lowest speed among the speeds PV1, PV2, and PV3. Then, the braking force BP for the control target wheel is gradually reduced. Thus, when the decrease speed Vb of the braking force BP is set to a low speed, the vehicle is less prone to understeer than when the decrease speed Vb is set to the second speed PV2 or the third speed PV3. Or the vehicle tends to understeer slowly.

  At a subsequent third timing t33, the absolute value of the steering angle A becomes less than the reference steering angle Ath2 by the steering of the steering wheel 30 by the driver. In this case, the braking force BP on the wheel to be controlled can cause a drag feeling that is felt by a driver trying to move the vehicle straight. Therefore, it is necessary to quickly cancel the braking force BP for the wheel to be controlled, and the decrease speed Vb is changed from the first speed PV1 to the third speed PV3. Then, the braking force BP for the control target wheel is rapidly reduced.

  As a result, the braking force BP for the target wheel becomes “0 (zero)” at the fourth timing t <b> 34 that is earlier than when the decrease speed Vb is maintained at the first speed PV <b> 1. That is, the reduction control, that is, the small turn control is quickly finished.

As described above, in the present embodiment, the following effects can be obtained.
(1) When the end condition of the small turn control is satisfied and the decrease control is performed, it is determined based on the traveling state of the vehicle whether or not the force to the outside in the turning direction applied to the vehicle is large. Then, when the force on the outside in the turning direction applied to the vehicle is large, the reduction control is performed so that the decreasing speed Vb is lower than when the force on the outside in the turning direction is small. That is, the force (that is, the braking force BP for the wheel to be controlled) facing the outward force in the turning direction applied to the vehicle is gradually reduced. Therefore, the reduction control is executed as compared with the conventional case where the reduction speed Vb is set to a constant value (for example, the third speed PV3) regardless of whether the force applied to the vehicle in the turning direction is large. When the vehicle turns, the vehicle is less likely to be understeered, or the vehicle is gently understeered. Therefore, when performing the decrease control with the establishment of the end condition of the small turn control, it is possible to reduce the feeling of jumping outward in the turning direction which is felt by the vehicle occupant.

  (2) When the absolute value of the steering angle A of the steering wheel 30 is greater than or equal to the reference steering angle Ath2, compared to the case where the absolute value of the steering angle A is less than the reference steering angle Ath2, the outer side in the turning direction applied to the vehicle The power to is great. Therefore, in the present embodiment, when the absolute value of the steering angle A of the steering wheel 30 is large, the decrease speed Vb of the braking force BP with respect to the control target wheel is lower than when the absolute value of the steering angle A is small. Set to As a result, the vehicle is less likely to be understeered or the vehicle is gently understeered as the braking force BP on the wheel to be controlled is gradually reduced according to the steering angle A of the steering wheel 30. Therefore, when performing the decrease control with the establishment of the end condition of the small turn control, it is possible to reduce the feeling of jumping outward in the turning direction which is felt by the vehicle occupant.

  (3) In the present embodiment, the decrease speed Vb is changed not only by the steering angle A of the steering wheel 30 but also by whether or not the accelerator pedal 20 is on. Specifically, when the accelerator pedal 20 is on, the vehicle body speed VS of the vehicle tends to be higher than when the accelerator pedal 20 is off. When the vehicle body speed VS becomes high, the force to the outside in the turning direction applied to the vehicle becomes larger than when the vehicle body speed VS is low. Therefore, when the accelerator pedal 20 is on, the decrease speed Vb is set to a lower speed than when the accelerator pedal 20 is off. Therefore, when there is a high possibility that the force to the outside in the turning direction is increased, the reduction speed Vb can be set to a low speed, and the vehicle occupant feels when performing the reduction control as the end condition for the small turn control is satisfied. The feeling of jumping out to the outside in the turning direction can be reduced.

  (4) The braking force BP for the wheel to be controlled has a magnitude based on the wheel cylinder pressure of the wheel cylinder corresponding to the wheel to be controlled. Some time lag occurs between the start of driving of the brake actuator 43 and the start of change of the wheel cylinder pressure. In addition, some time lag occurs between the time when the accelerator opening Ac starts to increase due to the operation of the accelerator pedal 20 by the driver and before the vehicle actually starts to accelerate. For this reason, if the decrease speed Vb is changed after the vehicle body speed VS has actually become high, the actual decrease speed of the braking force BP is not low even if the vehicle speed VS becomes high. A possibility arises. In this regard, in the present embodiment, the decreasing speed Vb is set by the accelerator opening degree Ac. That is, before the vehicle body speed VS of the vehicle actually becomes high, the decrease speed Vb is set to a low speed in advance. Therefore, the actual decrease speed of the braking force BP can be brought close to the vehicle body speed VS at that time, so that when the decrease control is performed in accordance with the establishment of the end condition of the small turn control, the vehicle occupant feels outside The feeling of jumping out can be reduced.

  (5) In the present embodiment, the decrease speed Vb is also changed by the vehicle body speed VS of the vehicle. Specifically, when the vehicle body speed VS is high, the force applied to the vehicle outward in the turning direction is greater than when the vehicle body speed VS is low. Therefore, when the vehicle body speed VS is high, the decrease speed Vb is set to be lower than when the vehicle body speed VS is low. Accordingly, when the force outward in the turning direction is large, the decrease speed Vb can be set to a lower speed than when the force outward in the turning direction is small. That is, it is possible to reduce the feeling of jumping outward in the turning direction, which is felt by the vehicle occupant when the reduction control is performed in accordance with the establishment of the end condition of the small turning control.

  (6) In the present embodiment, even during execution of the reduction control, the reduction speed Vb is adjusted according to the steering angle A of the steering wheel 30, whether the accelerator pedal 20 is on, and the vehicle body speed VS. Therefore, compared with the case where the reduction speed Vb cannot be changed after the start of the reduction control, the reduction speed Vb can be set to a value corresponding to the traveling state of the vehicle at that time, thereby satisfying the end condition of the small turning control. Accordingly, when performing the reduction control, it is possible to reduce the feeling of jumping outward in the turning direction which is felt by the vehicle occupant.

  (7) Further, in the present embodiment, based on the steering angle A of the steering wheel 30, it is determined whether or not the driver has an intention to move the vehicle straight. If it is determined that the driver has the intention to move the vehicle straight, the reduced speed Vb is set to the third speed PV3 regardless of whether the accelerator pedal 20 is turned on or off and the vehicle body speed VS. That is, the braking force BP for the control target wheel is quickly reduced. Therefore, the vehicle can be driven straight without causing the driver to feel the drag as much as possible.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment is different from the first embodiment in the method of setting the decrease rate Vb. Therefore, in the following description, parts different from those of the first embodiment will be mainly described, and the same or corresponding member configurations as those of the first embodiment are denoted by the same reference numerals, and redundant description will be omitted. Shall.

The small turn control end processing routine of the present embodiment will be described with reference to the flowchart shown in FIG.
In the small turning control end processing routine, the brake ECU 51 once ends the small turning control end processing routine when the small turning control flag FLG is OFF (step S30: NO). On the other hand, when the small turn control flag FLG is on (step S30: YES), the brake ECU 51 acquires the steering angle A of the steering 30 (step S31), and acquires the vehicle body speed VS of the vehicle (step S32). In this regard, in the present embodiment, the brake ECU 51 also functions as a steering angle related information acquisition unit and a vehicle speed related information acquisition unit.

  When both the first and second conditions are not satisfied (step S33: NO), the brake ECU 51 temporarily ends the small turn control end processing routine because the small turn control end condition is not satisfied. . On the other hand, when at least one of the first and second conditions is satisfied (step S33: YES), the brake ECU 51 sets the decreasing speed Vb because the end condition for the small turn control is satisfied (step S34). In the present embodiment, the decrease rate Vb is set using a map.

  This map is a map for setting the decrease speed Vb based on the steering angle A of the steering 30 and the vehicle body speed VS of the vehicle. For example, when the steering angle A of the steering wheel 30 is constant, the decreasing speed Vb is set to a smaller value when the vehicle body speed VS is high than when it is low. This is because it is estimated that the higher the vehicle body speed VS, the greater the force applied to the vehicle outward in the turning direction. When the vehicle body speed VS of the vehicle is constant, the decrease speed Vb is set to a larger value when the absolute value of the steering angle A of the steering wheel 30 is smaller than when the absolute value of the steering angle A is large. This is because it is estimated that the greater the absolute value of the steering angle A is, the greater the force applied to the vehicle is in the turning direction. That is, in step S34 of the present embodiment, the decrease speed Vb is set using the map.

  Then, the brake ECU 51 reduces the wheel cylinder pressure of the wheel cylinder corresponding to the rear wheel in the turning direction so that the braking force on the rear wheel in the turning direction is reduced at the decreasing speed Vb set in step S34. Reduction control is performed (step S35). Subsequently, the brake ECU 51 determines whether or not the reduction control is finished (step S36). If the reduction control has not been finished yet (step S36: NO), the brake ECU 51 once ends the small turn control end processing routine. On the other hand, when the decrease control is completed (step S36: YES), the brake ECU 51 sets the small turning control flag FLG to off (step S37), and then temporarily completes the small turning control end processing routine.

As described above, in this embodiment, in addition to the effects (6) and (7) in the first embodiment, the following effects can be further obtained.
(8) When the turning control end condition is satisfied and the reduction control is performed, the reduction control is performed so that the reduction speed Vb becomes lower as the force applied to the vehicle outward in the turning direction increases. That is, the force (that is, the braking force BP for the wheel to be controlled) facing the outward force in the turning direction applied to the vehicle is gradually reduced. Therefore, the reduction control is executed as compared with the conventional case where the reduction speed Vb is set to a constant value (for example, the third speed PV3) regardless of whether the force applied to the vehicle in the turning direction is large. When the vehicle turns, the vehicle is less likely to be understeered, or the vehicle is gently understeered. Therefore, when performing the decrease control with the establishment of the end condition of the small turn control, it is possible to reduce the feeling of jumping outward in the turning direction which is felt by the vehicle occupant.

  (9) In the present embodiment, the decreasing speed Vb is changed so as to follow the change in the steering angle A of the steering 30. Therefore, the decrease speed Vb can be set to an appropriate value according to the steering angle A of the steering 30 at that time. As a result, when the absolute value of the steering angle A of the steering wheel 30 is large and the force on the outside in the turning direction applied to the vehicle is large, the vehicle tends to understeer as much as the braking force BP against the control target wheel is gradually reduced. The vehicle tends to understeer slowly. Therefore, when performing the decrease control with the establishment of the end condition of the small turn control, it is possible to reduce the feeling of jumping outward in the turning direction which is felt by the vehicle occupant.

  (10) In the present embodiment, the decreasing speed Vb is changed so as to follow the change in the vehicle body speed VS of the vehicle. Therefore, the decrease speed Vb can be set to an appropriate value according to the vehicle body speed VS at that time. As a result, when the vehicle body speed VS is high and the force applied to the outside of the turning direction applied to the vehicle is large, the vehicle has an understeering tendency because the braking force BP against the wheel to be controlled is gradually reduced. Not easy to show, or vehicles tend to understeer slowly. Therefore, when performing the decrease control with the establishment of the end condition of the small turn control, it is possible to reduce the feeling of jumping outward in the turning direction which is felt by the vehicle occupant.

Each embodiment may be changed to another embodiment as described below.
In the second embodiment, the decrease speed Vb may be calculated using a function having the steering angle A of the steering wheel 30 and the vehicle body speed VS of the vehicle as variables.

  -In 1st Embodiment, you may abbreviate | omit the process of step S17. Also in this case, the decrease speed Vb can be set according to the accelerator opening degree Ac, which is an example of vehicle speed related information.

  In the first embodiment, a plurality of (for example, two) reference openings that are examples of the reference operation amount may be provided. When the accelerator opening degree Ac is less than the first reference opening degree, the decreasing speed Vb may be set to a larger value than when the accelerator opening degree Ac is equal to or more than the first reference opening degree. . Further, when the accelerator opening degree Ac is equal to or greater than the first reference opening degree and less than the second reference opening degree, the reduction speed Vb is set, and the accelerator opening degree Ac is less than the first reference opening degree. The accelerator opening degree Ac may be set to a value smaller than the case and larger than the case where the accelerator opening degree Ac is equal to or larger than the second reference opening degree. Even if comprised in this way, when the force of the turning direction outer side applied to a vehicle becomes large, the reduction speed Vb can be set to a low speed rather than the case where the force of the turning direction outer side is small.

  -In 1st Embodiment, you may abbreviate | omit the process of step S16. Also in this case, the decrease speed Vb can be set according to the vehicle body speed VS which is an example of the vehicle speed related information.

  In the first embodiment, a plurality of (for example, two) reference vehicle speeds may be provided. When the vehicle body speed VS is less than the first reference speed, the decrease speed Vb may be set to a larger value than when the vehicle body speed VS is equal to or higher than the first reference speed. Further, when the vehicle body speed VS is equal to or higher than the first reference speed and less than the second reference speed, the decrease speed Vb is smaller than that when the vehicle body speed VS is less than the first reference speed and The vehicle body speed VS may be set to a larger value than when the vehicle body speed VS is equal to or higher than the second reference speed. Even if comprised in this way, when the force to the outer side of the turning direction applied to the vehicle is large, the decreasing speed Vb can be set to a lower speed than when the force to the outer side of the turning direction is small.

  -When the vehicle travels on a slope, the vehicle body speed VS tends to be larger when the vehicle travels on a downhill than when the vehicle travels on an uphill, that is, to the outside in the turning direction. Power tends to increase. Therefore, the decreasing speed Vb may be set to a smaller value when the road surface on which the vehicle travels is a downhill road than when it is an uphill road. Even if comprised in this way, when the force of the turning direction outer side applied to a vehicle becomes large, the reduction speed Vb can be set to a low speed rather than the case where the force of the turning direction outer side is small. In this case, information indicating whether the road surface is an uphill road corresponds to the vehicle speed related information.

  Further, when the road surface on which the vehicle travels is a downhill road, the decrease speed Vb may be set to a smaller value when the road surface gradient is steep than when the road surface gradient is gentle. In this case, the road gradient corresponds to the vehicle speed related information.

  In addition, as a method of acquiring the road surface gradient, there are the following two methods. In the first method, a value obtained by time-differentiating the vehicle body speed VS calculated based on the detection signals from the wheel speed sensors SE3 to SE6 (also referred to as “vehicle body speed differential value”) and the detection from the acceleration sensor SE7. In this method, a difference from acceleration (also referred to as “G sensor value”) calculated based on a signal is obtained, and a gradient is estimated based on the difference. The second method is a method for acquiring gradient information from an information processing device (for example, a navigation device) mounted on a vehicle.

  -In 1st Embodiment, you may determine whether the wheel speed of wheel FR, FL, RR, RL is more than reference | standard wheel speed in step S17. The wheel speed used in this determination may be an average value of the wheel speeds of the respective wheels FR, FL, RR, RL, or may be an average value of the wheel speeds of the front wheels FR, FL that are drive wheels. . In this case, the wheel speed corresponds to the vehicle speed related information. In the second embodiment, the reduction speed Vb may be set using the wheel speed of the wheel instead of the vehicle body speed VS.

  When the acceleration in the front-rear direction of the vehicle is large, the vehicle body speed VS tends to be a large value, that is, the force toward the outside in the turning direction is likely to be larger than when the acceleration is small. Therefore, the decrease speed Vb may be set to a smaller value when the acceleration in the front-rear direction is a large value than when the acceleration is a small value. Even if comprised in this way, when the force of the turning direction outer side applied to a vehicle becomes large, the reduction speed Vb can be set to a low speed rather than the case where the force of the turning direction outer side is small. In this case, the acceleration in the front-rear direction of the vehicle corresponds to the vehicle speed related information.

  In each embodiment, the rotation speed of a crankshaft (not shown) of the engine 21, that is, the engine rotation speed may be acquired as vehicle speed related information, and the decrease speed Vb may be set based on the engine rotation speed.

  -In 1st Embodiment, you may abbreviate | omit each determination process of step S16, S17. Even in this configuration, the decrease speed Vb is set based on the steering angle A of the steering wheel 30 which is an example of the steering angle related information. Therefore, when the force to the outside in the turning direction applied to the vehicle increases, the decrease speed Vb can be set to a lower speed than when the force to the outside in the turning direction is small.

  In the first embodiment, a plurality of (for example, two) reference steering angles may be provided. When the absolute value of the steering angle A of the steering 30 is greater than or equal to the first reference steering angle, the decreasing speed Vb is smaller than when the absolute value of the steering angle A is less than the first reference steering angle. It may be set to a value. When the absolute value of the steering angle A is less than the first reference steering angle and greater than or equal to the second reference steering angle, the reduction speed Vb is set, and the absolute value of the steering angle A is the first reference steering. The absolute value of the steering angle A may be set to be smaller than that in the case where the absolute value of the steering angle A is less than the second reference steering angle. Even if comprised in this way, when the force of the turning direction outer side applied to a vehicle becomes large, the reduction speed Vb can be set to a low speed rather than the case where the force of the turning direction outer side is small.

  Some vehicles are equipped with a sensor for detecting acceleration in the width direction of the vehicle (hereinafter also referred to as “lateral G”), that is, a lateral G sensor. In such a vehicle, the lateral G sensor may be used to acquire the lateral G as steering angle related information, and the decrease speed Vb may be set based on the lateral G. In this case, when the lateral G is large, the decreasing speed Vb is set to a smaller value than when the lateral G is small.

  Some vehicles are equipped with a sensor for detecting the yaw rate of the vehicle, that is, a yaw rate sensor. In such a vehicle, the yaw rate may be acquired as steering angle related information using a yaw rate sensor, and the decrease speed Vb may be set based on the yaw rate. In this case, when the yaw rate is large, the decrease speed Vb is set to a smaller value than when the yaw rate is small.

  Some steering devices are equipped with a torque sensor for detecting steering torque instead of the steering angle sensor SE2. In such a vehicle, the estimated value of the steering angle may be calculated as steering angle related information based on the steering torque detected based on the detection signal from the torque sensor, and the decrease speed Vb may be set based on the estimated value of the steering angle. .

  -In 1st Embodiment, you may abbreviate | omit the determination process of step S14. Even in this configuration, the decrease speed Vb is set based on the vehicle speed related information (the vehicle speed VS, the accelerator opening degree Ac). Therefore, when the force to the outside in the turning direction applied to the vehicle increases, the decrease speed Vb can be set to a lower speed than when the force to the outside in the turning direction is small.

  In each embodiment, during the decrease control, the decrease speed Vb is held at a value based on the steering angle A, the accelerator opening Ac, and the vehicle body speed VS of the steering wheel 30 when the end condition of the small turn control is satisfied. Also good. In this case, during the execution of the reduction control, the reduction speed Vb is a constant speed.

  In each embodiment, even when the decrease control is performed in response to the operation button 55 being turned off during the small turn control, the decrease speed Vb is calculated based on the steering angle A of the steering wheel 30 and the accelerator opening degree Ac. Also, a value based on the vehicle body speed VS may be set.

In each embodiment, when the small turn control is executed, a braking force may be applied to the front wheel inside the turning direction of the vehicle (the right front wheel when turning right).
Next, technical ideas that can be grasped from the above embodiments and other embodiments will be added below.

(A) When turning control is performed to apply a braking force (BP) to a wheel on the inner side in the turning direction when the vehicle turns, and the end condition of the braking control on turning is subsequently satisfied, the wheel on the inner side in the turning direction In a vehicle brake control device that performs a decrease control to decrease the braking force (BP) against
Vehicle speed related information acquisition means (51, S12, S15, S32) for acquiring vehicle speed related information (VS, Ac) related to the vehicle body speed of the vehicle;
When performing the reduction control, based on the vehicle speed related information (VS, Ac) acquired by the vehicle speed related information acquisition means (51, S12, S15, S32), the greater the force on the outside in the turning direction applied to the vehicle, Control means (51, S21, S35) for slowing down the reduction speed (Vb) of the braking force (BP) for the wheels on the inner side in the turning direction.

  According to the above configuration, when the termination condition of the braking control during turning is satisfied and the reduction control is performed, the force on the outside in the turning direction applied to the vehicle is estimated based on the acquired vehicle speed related information. And reduction control is performed so that the decreasing speed of the braking force with respect to the wheel inside a turning direction becomes low, so that the force to the outside of the turning direction added to a vehicle is large. That is, as the force toward the outside in the turning direction increases, the braking force applied to the wheel inside the turning direction that opposes the force toward the outside in the turning direction is gradually reduced. Therefore, compared to the conventional case where the reduction speed is set to a constant value regardless of whether the force toward the outside in the turning direction is large or not, the vehicle is less likely to be understeered when the vehicle is turning with the execution of reduction control. Or the vehicle tends to understeer slowly. Therefore, when the braking force for the wheels on the inner side in the turning direction is reduced along with the completion of the condition for terminating the braking control during turning, it is possible to reduce the feeling of jumping outward in the turning direction which is felt by the vehicle occupant.

  DESCRIPTION OF SYMBOLS 30 ... Steering, 51 ... Brake ECU (control means, steering angle related information acquisition means, steering angle related information determination means, vehicle speed related information acquisition means, vehicle speed related information determination means) as a vehicle braking control device, A ... steering Steering angle as an example of angle related information, Ac ... accelerator opening (accelerator operation amount) as an example of vehicle speed related information, Acth ... reference opening as reference operation amount, Ath2 ... reference steering angle, BP ... braking force, Vb: Decrease speed, VS: Vehicle speed as an example of vehicle speed related information.

Claims (4)

When turning control is performed to apply a braking force (BP) to the wheels on the inner side in the turning direction when the vehicle turns, and the end condition of the braking control on turning is satisfied, the braking force on the wheels on the inner side in the turning direction is satisfied. In a vehicle brake control device that performs a reduction control to reduce (BP),
Steering angle related information acquisition means (51, S11, S31) for acquiring steering angle related information (A) that fluctuates with a change in the steering angle of the steering wheel (30);
When performing the decrease control, based on the steering angle related information (A) acquired by the steering angle related information acquisition means (51, S11, S31), as the force to the outside in the turning direction applied to the vehicle increases, the turning And a control means (51, S21, S35) for slowing down the rate of decrease (Vb) in braking force (BP) for the inner wheel in the direction. Steering angle related information determination for determining whether or not a force on the outside in the turning direction applied to the vehicle is large based on the steering angle related information (A) acquired by the steering angle related information acquisition means (51, S11, S31). Means (51, S14),
The control means (51, S21) moves outward in the turning direction applied to the vehicle when it is determined by the steering angle related information determination means (51, S14) that the force to the outside in the turning direction applied to the vehicle is large. 2. The vehicle braking according to claim 1, wherein a rate of decrease (Vb) of the braking force (BP) applied to the wheels on the inner side in the turning direction is made slower than in a case where it is determined that the force of the vehicle is small. Control device. Vehicle speed related information acquisition means (51, S12, S15, S32) for acquiring vehicle speed related information (VS, Ac) related to the vehicle body speed of the vehicle;
The control means (51, S21, S35), based on the vehicle speed related information (VS, Ac) acquired by the vehicle speed related information acquisition means (51, S12, S15, S32) when performing the decrease control, 3. The vehicle according to claim 1, wherein a decrease rate (Vb) of a braking force (BP) applied to a wheel on the inner side in the turning direction is decreased as a force applied to the outer side in the turning direction is increased. Braking control device. Vehicle speed related information for determining whether or not a force on the outside in the turning direction applied to the vehicle is large based on the vehicle speed related information (VS, Ac) acquired by the vehicle speed related information acquisition means (51, S12, S15, S32). A determination unit (51, S16, S17);
The control means (51, S21) turns the vehicle when the vehicle speed related information determination means (51, S12, S15, S32) determines that the force to the outside in the turning direction applied to the vehicle is large. 4. The reduction speed (Vb) of the braking force (BP) with respect to the wheel on the inner side in the turning direction is made slower than in a case where it is determined that the force toward the outer side in the direction is small. Vehicle braking control device.

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