JP2014015082A - Braking control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a braking control device that is capable of reducing a force required for turning while holding a vehicle in a stop state.SOLUTION: If it is determined that a vehicle 11 is stopped in a state where a braking device 15 is operating based on a brake signal acquired from a brake sensor 39 and a detection result of a wheel speed sensor 40, a braking state of the braking device 15 is controlled so that a braking force applied to front wheels 12 is reduced and a braking force applied to rear wheels 13 is kept.

Description

  The present invention relates to a braking control device mounted on a vehicle.

  Conventionally, in a suspension device for steered wheels, the distance in the vehicle width direction between the point where the downward extension line of the kingpin shaft intersects the road surface and the center of the ground contact surface (hereinafter referred to as “wheel contact point”) of the steered wheel. Is called a scrub radius (or kingpin offset) (for example, Patent Document 1). When the steering wheel is steered to steer during low-speed running, the steered wheel rotates on the road surface while rotating (revolving motion) with its wheel contact point drawing an arc corresponding to the scrub radius around the kingpin axis. Roll over. Therefore, in the case of a vehicle with a large scrub radius, the steered wheels can be made to roll more easily than in the case of a vehicle with a small scrub radius, so that it is possible to steer with a light force.

JP 2010-47193 A

  By the way, in a state where a braking device such as a brake is operating when the vehicle is stopped, the rolling (rotation) of the wheel is restricted. Therefore, even if the vehicle has a large scrub radius, a large force is required for turning when the vehicle is stopped with the wheels braked (rolling regulation).

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a braking control device that can reduce the force required for turning while maintaining the stationary state of the vehicle. is there.

  A braking control device that solves the above problems regulates rolling of the wheels on a road surface by applying braking force to a plurality of wheels including a steered wheel that revolves around an axis that intersects the road surface during turning. A braking detection unit for detecting an operating state of the braking device in a vehicle equipped with the braking device to perform, a stop detection unit for detecting a stop state of the vehicle, a detection result of the braking detection unit, and a detection result of the stop detection unit Based on the above, when it is determined that the vehicle is stopped in a state where the braking device is activated, the braking force applied to at least one of the steered wheels is reduced, and at least one other than the steered wheels is reduced. And a control unit that controls a braking state of the braking device so as to maintain a braking force on the wheels.

  According to the above configuration, the steered wheels with reduced braking force are allowed to roll on the road surface. Therefore, the steered wheels are restrained from being dragged with respect to the road surface when steered, and can revolve around an axis that intersects the road surface while rolling. Therefore, it is possible to steer with a light force compared to the case where the steered wheel is steered in a state where the rolling of the steered wheel is restricted. In addition, since the braking force for at least one wheel other than the steered wheels that is allowed to roll is maintained, the stopped state of the vehicle is maintained. Therefore, it is possible to reduce the force required for turning while maintaining the stop state of the vehicle.

In the above-described braking control device, it is preferable that the control unit maintain a braking force for a non-steered wheel among the wheels when the braking force applied to the steered wheel is reduced.
According to the above configuration, the non-steered wheel maintains a braked state even during the turning with respect to the steered wheel that revolves around the shaft during the turning. Therefore, in the above-described braking control device, by maintaining the braking force for the non-steered wheels, the stop state of the vehicle can be maintained while suppressing an increase in force necessary for turning.

  The braking control device further includes a steering detection unit that detects a steering state of a steering device that is steered when the steered wheels are steered, and the control unit stops the vehicle while the braking device is operating. It is preferable to reduce the braking force applied to the steered wheels when it is determined that the steering device is steered for the steered state.

  According to the above configuration, the braking force applied to the steered wheels when the steering device is steered can be reduced. Therefore, it is possible to reduce the braking force applied to the steered wheels when the steered wheels actually revolve around the axis.

  The braking control device further includes an inclination detection unit that detects the inclination of the vehicle, and the control unit determines that the inclination of the vehicle is larger than an inclination threshold based on a detection result of the inclination detection unit. It is preferable to maintain the braking force applied to the steered wheels.

  According to the above configuration, for example, when the vehicle stops with a braking force applied to the wheels on a slope or the like, and the inclination of the vehicle at that time is larger than the inclination threshold, the vehicle is applied to the steered wheels even at the time of turning. Maintain braking force. Therefore, when the vehicle is stopped in a place where it is difficult to maintain a stop state (such as a slope) unless braking force is applied to the wheels, the braking force applied to each wheel is maintained even during steering. The maintenance of the stop state can be prioritized over the steering.

  In the above braking control device, the steered wheels are provided such that a grounding point that is an intersection of a downwardly extending line of the shaft and a road surface is located on the inner side in the vehicle width direction from the center of the grounding surface of the steered wheels. It is preferable.

  According to the above configuration, since the steered wheels are provided so that the grounding point between the extension line of the shaft and the road surface is located on the inner side in the vehicle width direction from the center of the grounding surface, the grounding point is outside the center of the grounding surface. Compared with the case where it is located in, the scrub radius used as the revolution radius of the steered wheel at the time of turning can be set large. As a result, by setting the scrub radius large, it becomes easier for the steered wheels to roll on the road surface when revolving around the shaft, and the force required for steer can be further reduced.

  ADVANTAGE OF THE INVENTION According to this invention, the braking control apparatus which can reduce the force required for steering can be provided, maintaining the stop state of a vehicle.

The block diagram which shows schematic structure of the vehicle carrying the braking control apparatus of one Embodiment which concerns on this invention. The schematic diagram at the time of seeing the right front wheel and steering device in a vehicle from the front. The schematic diagram at the time of seeing the right front wheel and steering device from the top at the time of steering. The flowchart which shows a steering process routine.

Hereinafter, an embodiment in which the present invention is embodied in a braking control device mounted on a vehicle will be described with reference to the drawings.
As illustrated in FIG. 1, the vehicle 11 includes a pair of front wheels 12 and a pair of rear wheels 13 as an example of a plurality of (four in the present embodiment) wheels. Further, the vehicle 11 is equipped with an engine 14, a braking device 15, a steering device 16, and a braking control device 17.

  The pair of front wheels 12 is provided at a front position in the traveling direction of the vehicle 11 with an interval in the vehicle width direction intersecting the traveling direction. On the other hand, the pair of rear wheels 13 is provided at a rear position in the traveling direction of the vehicle 11 with an interval in the vehicle width direction.

  The engine 14 generates a driving force based on an operation amount of an accelerator pedal (not shown) by the driver. The driving force output from the engine 14 is transmitted to the front wheels 12 through the drive shaft 19. Then, the front wheel 12 rotates around the drive shaft 19, and the vehicle 11 travels by rolling on the road surface 20 shown in FIG. Further, as the vehicle 11 travels, the rear wheel 13 rotates around a spindle (not shown) and rolls on the road surface 20 like the front wheel 12.

  As shown in FIG. 1, the braking device 15 includes a brake pedal 22, a braking device 23, a hydraulic pressure generating device 24, and a brake actuator 25. The brake pedal 22 is operated by the driver when operating the braking device 15. Moreover, the brake device 23 is provided in each front wheel 12 and each rear wheel 13, respectively. Then, the hydraulic pressure generator 24 generates a brake hydraulic pressure corresponding to the operating force of the brake pedal 22 by the driver. Furthermore, the brake actuator 25 is connected to each brake device 23 in a state where the braking force applied to the front wheel 12 and the rear wheel 13 can be individually adjusted.

  That is, in this vehicle 11, when the brake pedal 22 is depressed by the driver, the braking device 15 is activated. When the braking device 15 is activated, a braking force corresponding to the operation amount of the brake pedal 22 is applied to the front wheels 12 and the rear wheels 13. Therefore, when the braking device 15 is activated, the rolling of the front wheels 12 and the rear wheels 13 on the road surface 20 is restricted.

  As shown in FIG. 1, the steering device 16 includes a steering wheel 27, a steering shaft 28, a gear mechanism 29, a tie rod 30, a knuckle arm 31, and a steering knuckle 32.

  The steering wheel 27 is operated by the driver when the vehicle 11 is steered. The steering shaft 28 transmits the rotational force accompanying the steering (turning) of the steering wheel 27 to the gear mechanism 29. The turning power transmitted to the gear mechanism 29 is converted into power in the vehicle width direction. That is, the tie rods 30 connected to both sides of the gear mechanism 29 in the vehicle width direction reciprocate along the vehicle width direction based on the power transmitted from the gear mechanism 29. The knuckle arm 31 connected to the tie rod 30 is formed integrally with the steering knuckle 32.

  Specifically, as shown in FIG. 2, the steering knuckle 32 is provided so as to rotate about an axis A that intersects the road surface 20. Further, the radially outer surface of the front wheel 12 is a ground contact surface 12 a that contacts the road surface 20. The center in the vehicle width direction of the portion in contact with the road surface 20 in the ground contact surface 12a is defined as the ground contact center 34. Further, the intersection of the vertical extension line of the axis A in the vertical direction and the road surface 20 is defined as a ground contact point 35. The front wheel 12 is provided such that the ground contact point 35 is located on the inner side in the vehicle width direction than the ground contact center 34.

  Therefore, as shown in FIG. 3, the front wheel 12 that rotates integrally with the steering knuckle 32 revolves around the axis A as the steering knuckle 32 rotates. That is, when the steering wheel 27 is steered and the tie rod 30 moves in the vehicle width direction, the front wheels 12 rotate on the road surface 20 so that the ground contact center 34 draws an arc whose rotation radius is the distance from the axis A. To do.

  Therefore, in the case of this embodiment, the front wheel 12 functions as an example of a steered wheel to which a steered angle is given when the steering wheel 27 is steered (turned) for steering. On the other hand, the rear wheel 13 functions as an example of a non-steered wheel that maintains a state in which a turning angle is not given regardless of steering of the steering wheel 27.

Next, the braking control device 17 will be described.
As shown in FIG. 1, the braking control device 17 includes a control unit 37, an operation button 38, a brake sensor 39, a wheel speed sensor 40, a steering sensor 41, and a tilt sensor 42. And the control part 37 controls the braking state of the braking device 15 based on the input information of the operation button 38, and each detection result which the brake sensor 39, the wheel speed sensor 40, the steering sensor 41, and the inclination sensor 42 detected. . Further, when the operation button 38 is operated by the driver, the control mode of the braking device 15 is changed.

  The brake sensor 39 detects the operating state of the braking device 15 and outputs the detection result to the control unit 37 as a brake signal. Specifically, the brake sensor 39 outputs an ON signal when the brake pedal 22 is depressed by the driver and the braking device 15 is operating. On the other hand, the brake sensor 39 outputs an off signal when the brake pedal 22 is released by the driver and the braking device 15 is not operating. Therefore, the brake sensor 39 functions as an example of a braking detection unit that detects the operating state of the braking device 15.

  The wheel speed sensor 40 detects the stop state of the vehicle 11 and outputs the detection result to the control unit 37. Specifically, at least one wheel speed sensor 40 (the same number as the wheels in the present embodiment) is provided and detects the wheel speed of at least one of the front wheels 12 and the rear wheels 13. In the present embodiment, all wheel speeds of the front wheel 12 and the rear wheel 13 are detected. That is, when the vehicle 11 is stopped, the front wheel 12 and the rear wheel 13 are also stopped, so that a detection signal indicating that the wheel speed is zero is output. Therefore, the wheel speed sensor 40 functions as an example of a stop detection unit that detects the stop state of the vehicle 11.

  The steering sensor 41 detects the steering angle of the steering wheel 27 and outputs it to the control unit 37. The steering sensor 41 outputs a positive / negative value corresponding to the direction of turning when the steering wheel 27 is turned to turn the vehicle 11 to the right or left. Specifically, a detection signal indicating that the steering angle is zero is output during straight traveling. When turning, the output value increases as the steering angle increases. Therefore, the steering sensor 41 functions as an example of a steering detection unit that detects the steered state of the steering device 16.

  The tilt sensor 42 detects the tilt of the vehicle 11 and outputs a value corresponding to the tilt angle to the control unit 37. That is, for example, when the vehicle 11 is located on a slope such as a downhill road or an uphill road, the vehicle 11 is inclined according to the inclination of the road surface 20. Therefore, a positive / negative value corresponding to the direction in which the tilt sensor 42 tilts is output as the tilt angle. Therefore, the tilt sensor 42 functions as an example of a tilt detection unit that detects the tilt of the vehicle 11.

  Next, based on the flowchart shown in FIG. 4, the processing content of the steering process routine which the control part 37 performs is demonstrated. The steering process routine is started by the control unit 37 when an ignition switch (not shown) of the vehicle 11 is turned on. And after execution of this steering process routine is complete | finished, whenever operation of the brake pedal 22 by a driver | operator is cancelled | released and the vehicle 11 begins to drive | work, the process of this routine by the control part 37 will be performed again. .

  First, as shown in FIG. 4, in step S <b> 101, the control unit 37 acquires the wheel speeds of the front wheels 12 and the rear wheels 13 from the wheel speed sensor 40. In step S102, the control unit 37 determines whether or not the traveling speed of the vehicle 11 (hereinafter referred to as “vehicle speed”) is zero based on the acquired wheel speed. That is, the control unit 37 determines that the vehicle speed is not zero when at least one wheel speed is not zero (step S102: NO), and returns to step S101. On the other hand, when all the wheel speeds are zero, the control part 37 judges that the vehicle 11 stops and a vehicle speed is zero (step S102: YES), and transfers the process to step S103.

  In step S103, the control unit 37 acquires the steering angle of the steering wheel 27 from the steering sensor 41 and temporarily stores it. In step S <b> 104, the control unit 37 acquires an inclination angle from the inclination sensor 42. In step S105, the control unit 37 determines whether or not the acquired inclination angle is less than the inclination threshold value stored in the storage unit (not shown). That is, when the vehicle 11 stops on a steep slope and the inclination angle is equal to or greater than the inclination threshold (step S105: NO), the control unit 37 determines that the vehicle 11 is stopped on the slope and turns the vehicle. The processing routine ends. On the other hand, when the inclination angle is less than the inclination threshold (step S105: YES), the process proceeds to step S106.

  In step S <b> 106, the control unit 37 acquires a brake signal from the brake sensor 39. In step S107, the control unit 37 determines whether or not a brake operation by the driver is being performed. That is, if the control unit 37 acquires an ON signal from the brake sensor 39 and determines that the brake operation is being performed (step S107: YES), the control unit 37 proceeds to step S108.

  In step S <b> 108, the control unit 37 acquires the steering angle of the steering wheel 27 from the steering sensor 41. Furthermore, in step S109, the control unit 37 determines whether or not a steering operation has been performed by the driver. Specifically, the control unit 37 compares the steering angle acquired in step S103 and temporarily stored with the steering angle acquired in step S108. If the difference between the steering angles is larger than the steering angle threshold value stored in the storage unit (not shown), it is determined that there is a turning operation (step S109: YES), and the process proceeds to step S110. To do.

  In step S <b> 110, the control unit 37 controls the braking state of the braking device 15 so as to reduce the braking force applied to the front wheels 12 and maintain the braking force for the rear wheels 13. And the control part 37 complete | finishes a steering process routine.

  On the other hand, when an off signal is acquired from the brake sensor 39 in step S106, in step S107, the control unit 37 determines that the brake operation is not performed (step S107: NO), and the process proceeds to step S111. Transition. If the difference between the steering angles is smaller than the steering angle threshold value in step S109, the control unit 37 determines that there is no steering operation (step S109: NO), and the process proceeds to step S111.

  In step S111, the control unit 37 acquires the wheel speed as in step S101. Further, in step S112, the control unit 37 determines whether or not the vehicle speed is zero based on the wheel speed acquired in step S111, as in the case of step S102. When the vehicle speed is zero (step S112: YES), the control unit 37 determines that the vehicle 11 is stopped, and the process proceeds to step S106. On the other hand, when the vehicle speed is not zero (step S112: NO), the control unit 37 determines that the vehicle 11 is traveling, shifts the process to step S101, and performs the processes after step S101 again. Run.

  Next, with regard to the action of the braking control device 17 in the present embodiment, paying attention to the action in the case of performing a so-called stationary operation, in which a steering angle is given to the front wheels 12 for turning while the vehicle 11 is stopped. explain.

  When the driver depresses the brake pedal 22, the braking device 15 applies a braking force corresponding to the operation amount of the brake pedal 22 to the front wheels 12 and the rear wheels 13. Therefore, when the brake pedal 22 is depressed in the traveling vehicle 11, the vehicle 11 stops at a reduced speed. Further, when the brake pedal 22 is depressed in the stopped vehicle 11, the rolling of the front wheels 12 and the rear wheels 13 on the road surface 20 is restricted.

  When the driver turns the steering wheel 27 for steering in a state where the vehicle 11 is stopped, the ground contact center 34 of the ground contact surface 12a on the front wheel 12 revolves around the axis A. At this time, the front wheel 12 is allowed to roll on the road surface 20 because the braking force applied from the braking device 15 is reduced. Therefore, the front wheel 12 is restrained from being dragged with respect to the road surface 20 by the ground contact center 34, and revolves around the axis A so as to roll on the road surface 20.

According to the above embodiment, the following effects can be obtained.
(1) During the stationary operation, rolling of the front wheel 12 with reduced braking force relative to the road surface 20 is allowed. Therefore, the front wheel 12 is restrained from being dragged with respect to the road surface 20 by the ground contact center 34 on the ground contact surface 12a when turning, and can revolve around the axis A intersecting the road surface 20 while rolling. it can. Therefore, it is possible to steer with a lighter force than when steering in a state where the rolling of the front wheels 12 is restricted. Further, since the braking force for the rear wheels 13 other than the front wheels 12 allowed to roll is maintained, the vehicle 11 is maintained in the stopped state. Therefore, the force required for turning can be reduced while maintaining the stop state of the vehicle 11.

  (2) In contrast to the front wheel 12 that revolves around the axis A during turning, the rear wheel 13 maintains a braked state during turning. Therefore, by maintaining the braking force with respect to the rear wheel 13, the stop state of the vehicle 11 can be maintained while suppressing an increase in force necessary for turning.

  (3) When the steering wheel 27 is steered for turning, the braking force applied to the front wheels 12 can be reduced. Accordingly, the braking force applied to the front wheel 12 when the front wheel 12 actually revolves can be reduced.

  (4) For example, when the vehicle 11 stops on a slope or the like with braking force applied to the front wheels 12 and the rear wheels 13, and the tilt angle of the vehicle 11 at that time is larger than the tilt threshold, The braking force applied to the front wheel 12 is maintained. Therefore, when the braking force is not applied to the front wheels 12 and the rear wheels 13, the vehicle 11 is applied to the front wheels 12 and the rear wheels 13 when the vehicle 11 is stopped in a place where it is difficult to maintain the stopped state (such as a slope). By maintaining the power even at the time of turning, priority can be given to maintaining the stop state rather than turning.

  (5) Since the front wheel 12 is provided so that the ground contact point 35 between the extension line of the axis A and the road surface 20 is located inward of the ground contact center 34 of the ground contact surface 12a of the front wheel 12 in the vehicle width direction, the ground contact point 35 is The scrub radius that is the revolution radius of the front wheels 12 at the time of turning can be set larger than in the case where the ground contact surface 12a is positioned outside the ground contact center 34. As a result, by setting the scrub radius large, it becomes easier to roll on the road surface 20 when the front wheel 12 revolves around the axis A, and the force required for turning can be further reduced.

In addition, you may change the said embodiment as follows.
In the above embodiment, a reduction mode for reducing the braking force of the front wheels 12 and a maintenance mode for maintaining the braking force of the front wheels 12 may be switched according to the operation of the operation button 38 by a driver or the like. That is, for example, when the stationary operation is performed in the state where the reduction mode is selected, the braking force of the front wheels 12 may be reduced.

  In the above embodiment, the braking force may be applied again to the front wheels 12 with the reduced braking force in response to the operation of the operation button 38 by a driver or the like. That is, for example, when the driver operates the operation button 38 after the installation operation is finished, a braking force may be applied to the front wheels 12. Further, the control unit 37 may determine the end of the stationary operation and apply a braking force to the front wheels 12.

  In the above embodiment, the front wheel 12 may be provided such that the ground contact point 35 is located outside the ground contact center 34 in the vehicle width direction. That is, since the front wheel 12 rotates about the axis A, if the grounding point 35 and the grounding center 34 are not aligned and separated from each other, the distance between the grounding point 35 and the grounding center 34 is increased. A revolving motion can be made about the axis A so as to draw an arc having a turning radius. Further, the axis A may be inclined with respect to the road surface 20.

  In the above embodiment, the inclination angle acquired from the inclination sensor 42 may not be used for controlling the braking state. Further, the tilt sensor 42 may not be provided. That is, the braking state of the braking device 15 may be controlled regardless of where the vehicle 11 is located.

  -In the said embodiment, according to the inclination angle acquired from the inclination sensor 42, you may change the number of the wheels which reduce braking force. For example, when stopping on a flat road surface, the braking force of two front wheels 12 may be reduced, and when stopping on a gentle slope, the braking force of one front wheel 12 may be reduced. .

  In the above embodiment, the steering angle acquired from the steering sensor 41 may not be used for controlling the braking state. Further, the steering sensor 41 may not be provided. That is, when the vehicle 11 stops, the braking force of the front wheels 12 may be reduced regardless of the operation of the steering wheel 27.

  In the above embodiment, the steering sensor 41 may be a torque sensor that detects steering torque and outputs it to the control unit 37. And the control part 37 may judge that there exists steering operation, when the magnitude | size of the acquired steering torque is larger than a torque threshold value.

  In the above embodiment, the braking force applied to the rear wheel 13 may be reduced when the braking force applied to the front wheel 12 is reduced. That is, for example, among the pair of rear wheels 13, the braking force of one rear wheel 13 may be reduced and the braking force of the other rear wheel 13 may be maintained.

  In the above embodiment, the vehicle 11 may be a tricycle having three wheels or a vehicle having five or more wheels. And it is sufficient if at least one of the wheels is a steered wheel that revolves around the axis A. That is, all the wheels may be steered wheels. When a plurality of steered wheels are provided, reducing the braking force of at least one steered wheel reduces the force required for steering compared to maintaining the braking force of all steered wheels. can do.

  -In the said embodiment, the braking device 15 can be arbitrarily employ | adopted if it can adjust the braking force with respect to a wheel, such as a hydraulic brake, an air brake, a steam brake, and a hydraulic brake. The brake sensor 39 may detect the operating state of the braking device 15 by detecting the brake pressure applied to the front wheels 12 and the rear wheels 13.

  In the above embodiment, the wheel speed sensor 40 may detect the stop state of the vehicle 11 from the rotation state of the axle such as the drive shaft 19.

  DESCRIPTION OF SYMBOLS 11 ... Vehicle, 12 ... Front wheel (wheel, steered wheel), 12a ... Ground surface, 13 ... Rear wheel (wheel, non-steered wheel), 15 ... Braking device, 16 ... Steering device, 17 ... Braking control device, 20 ... Road surface 34 ... grounding center (center), 35 ... grounding point, 37 ... control unit, 39 ... brake sensor (braking detection unit), 40 ... wheel speed sensor (stop detection unit), 41 ... steering sensor (steering detection unit), 42: Tilt sensor (tilt detector), A: Axis.

Claims (5)

The braking in a vehicle equipped with a braking device that restricts rolling of the wheels on the road surface by applying a braking force to a plurality of wheels including a steered wheel that revolves around an axis that intersects the road surface when turning. A braking detector for detecting the operating state of the device;
A stop detection unit for detecting a stop state of the vehicle;
Based on the detection result of the braking detection unit and the detection result of the stop detection unit, when it is determined that the vehicle is stopped in a state where the braking device is activated, the vehicle is given to at least one steered wheel. A braking control device comprising: a control unit that controls a braking state of the braking device so as to reduce a braking force and maintain a braking force for at least one of the wheels other than the steered wheels. The braking control device according to claim 1, wherein the control unit maintains a braking force for a non-steered wheel among the wheels when reducing a braking force applied to the steered wheel. A steering detector for detecting a steering state of a steering device that is steered when the steered wheels are steered;
The control unit reduces a braking force applied to the steered wheels when it is determined that the steering device is steered for turning in a state where the vehicle is stopped while the braking device is operating. The braking control device according to claim 1 or 2. The steering wheel further includes a tilt detection unit that detects the tilt of the vehicle, and the control unit determines that the vehicle tilt is greater than a tilt threshold based on a detection result of the tilt detection unit. The braking control device according to any one of claims 1 to 3, wherein a braking force applied to the vehicle is maintained. The said steered wheel is provided so that the grounding point which is an intersection of the downward extension line of the said axis | shaft and a road surface may be located inside a vehicle width direction rather than the center of the grounding surface of the said steered wheel. The braking control device according to claim 4.