JP2018062294A - Vehicle braking control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle braking control device, which is configured to be able to execute left-right wheel independent control by which braking force of left and right rear wheels is controlled independently so that respective slip rates of the left and right rear wheels are equal to a target slip rate, while enhancing robustness to disturbances such as variation in control.SOLUTION: The vehicle braking control device controls a brake device 20 that can control independently braking force of left and right rear wheels 10RL and 10RR. Braking control to be performed by the braking control device includes left and right wheel common control by which braking force of the left and right rear wheels 10RL and 10RR is controlled so that the braking force thereof is equal to each other and left and right wheel independent control by which braking force of the left and right rear wheels 10RL and 10RR is controlled independently so that respective slip rates S of the left and right rear wheels 10RL and 10RR are equal to a target slip rate St. The braking control device is configured to execute the left and right wheel common control prior to starting the left and right wheel independent control when a condition A for starting the left and right wheel independent control is satisfied.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a vehicle braking control device, and more particularly to a braking control device suitable for controlling a vehicle in which left and right wheel independent control for independently controlling the braking force of left and right rear wheels is performed.

  Patent Document 1 discloses a vehicle braking force control device that can independently control the braking forces of the left and right rear wheels. According to this control device, the braking forces of the left and right rear wheels are individually controlled so that the rear wheel slip degree (for example, the slip ratio) becomes the target slip degree. This target slip degree is set to be lower by a predetermined amount than the front wheel slip degree. The target slip degree is corrected so that the target slip degree of the rear wheel on the contact load increasing side is higher than the target slip degree of the rear wheel on the contact load decreasing side.

JP 2012-096610 A JP-A-3-042361

  In general, the center of gravity of the vehicle is often shifted in the left-right direction from the center of the vehicle, and also changes due to changes in the number of passengers. When the center of gravity of the vehicle deviates in this way, a difference occurs in the ground contact load between the left and right wheels. If the left and right wheels have different ground loads, when the same braking force is applied to the left and right wheels, the vehicle tends to deflect toward the ground load reduction side even if the steered wheels are in the straight ahead position. This is because the degree of wheel slip during braking is proportional to the ground contact load, so if the left and right wheels have different ground contact loads due to a shift in the center of gravity of the vehicle from the vehicle center, the same braking force will be applied to the left and right wheels. This is because, when given, the wheel speed of the wheel on the ground load reduction side becomes lower than the wheel speed of the wheel on the opposite side.

  Therefore, it is conceivable to perform the left and right wheel independent control in such a manner that the braking force of the left and right rear wheels is independently controlled so that the respective slip degrees (for example, slip ratio) of the left and right rear wheels are equal to the target slip degree. . According to such left and right wheel independent control, when braking is performed in a situation where the ground contact loads of the left and right wheels are different as described above, the braking force on the ground load increasing side becomes the braking force on the ground load decreasing side. The braking force of the left and right rear wheels can be controlled so as to be larger. As a result, a yaw moment (so-called anti-spin moment) for canceling the yaw moment of the vehicle to be deflected toward the contact load decreasing side can be applied to the left and right rear wheels. Thereby, the braking stability of the vehicle can be enhanced.

  In the initial stage of braking performed in a situation where the ground contact loads of the left and right wheels are different, the slip degree of each wheel tends to fluctuate transiently. If the left and right wheel independent control described above is performed at the beginning of such braking, there is a concern that the left and right wheel independent control may adversely affect the braking stability of the vehicle. More specifically, when the left and right wheel independent control is started early in order to correct an early change in the slip degree of each wheel in the initial stage of braking, the behavior of the vehicle is stably converged due to factors such as control variations. Can be difficult.

  The present invention has been made in view of the above-described problems, and enhances robustness against disturbances such as control variations, while allowing the left and right rear wheels to have the same slip degree as the target slip degree. It is an object of the present invention to provide a braking control device for a vehicle capable of performing left and right wheel independent control for independently controlling wheel braking force.

  The vehicle braking control device according to the present invention is a vehicle braking control device including a braking device capable of independently controlling the braking force of the left and right rear wheels. In the braking force control performed by the braking control device, the left and right rear wheel common control for controlling the braking force so that the braking forces of the left and right rear wheels are equal, and the respective slip degrees of the left and right rear wheels are equal to the target slip degree. Left and right wheel independent control for independently controlling the braking force of the left and right rear wheels. The braking control device is configured to execute the left and right wheel common control prior to the start of the left and right wheel independent control when the start condition of the left and right wheel independent control is satisfied.

  The left and right wheel common control performed upon establishment of the start condition, when there is a request to reduce the braking force of one of the left and right rear wheels, equally reduces the braking force of both the left and right rear wheels according to the request. It is also possible to perform control.

  According to the present invention, when the start condition for the left and right wheel independent control is satisfied, the right and left wheel independent control is not started immediately after the start condition is satisfied, but before the start of the left and right wheel independent control. Common control is executed. Thereby, it is suppressed that the left and right wheel independent control intervenes immediately in the initial stage of braking. For this reason, it becomes possible to perform the left and right wheel independent control while improving the robustness against disturbances such as control variations. As a result, high braking stability of the vehicle can be ensured.

It is the schematic showing an example of the composition of vehicles to which the braking control device of Embodiment 1 of the present invention is applied. It is a conceptual diagram for demonstrating the left-right wheel independent control which concerns on Embodiment 1 of this invention. It is a figure for demonstrating an example of the adjustment of the braking force of the right-and-left rear wheel by the left-right wheel independent control which concerns on Embodiment 1 of this invention. It is a flowchart which shows the routine performed by ECU in order to implement | achieve the braking control which concerns on Embodiment 1 of this invention. It is a flowchart which shows the routine performed by ECU in order to implement | achieve the braking control which concerns on Embodiment 2 of this invention.

Embodiment 1 FIG.
[Configuration of Embodiment 1]
FIG. 1 is a schematic diagram illustrating an example of a configuration of a vehicle 1 to which the braking control device according to the first embodiment of the present invention is applied. As shown in FIG. 1, the vehicle 1 of the present embodiment includes four wheels 10. In the following description, the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel are referred to as 10FL, 10FR, 10RL, and 10RR, respectively. Further, the front wheels may be collectively referred to as 10F, and the rear wheels may be collectively referred to as 10R.

  The vehicle 1 includes a steering device 12 having a steering wheel 12a. The steering device 12 is configured to change the direction of the front wheels 10F that are the steering wheels of the vehicle 1 in accordance with the operation of the steering wheel 12a by the driver.

  The vehicle 1 includes a brake device 20. The brake device 20 includes a brake pedal 22, a master cylinder 24, a brake actuator 26, a brake mechanism 28, and a hydraulic pipe 30. The master cylinder 24 generates a hydraulic pressure corresponding to the depression force of the brake pedal 22 and supplies the generated hydraulic pressure to the brake actuator 26.

  The brake actuator 26 has a hydraulic circuit (not shown) interposed between the master cylinder 24 and the brake mechanism 28. The hydraulic circuit includes a pump for increasing the brake hydraulic pressure without relying on the master cylinder pressure, a reservoir for storing brake fluid, and a plurality of electromagnetic valves.

  A brake mechanism 28 is connected to the brake actuator 26 via a hydraulic pipe 30. The brake mechanism 28 is disposed on each wheel 10. The brake actuator 26 distributes the brake hydraulic pressure to the brake mechanism 28 of each wheel 10. More specifically, the brake actuator 26 can supply brake hydraulic pressure to the brake mechanism 28 of each wheel 10 using the master cylinder 24 or the pump as a pressure source. The brake mechanism 28 has a wheel cylinder 28a that operates according to the supplied brake hydraulic pressure.

  Furthermore, the brake actuator 26 can independently adjust the brake hydraulic pressure applied to each wheel 10 by controlling various electromagnetic valves provided in the hydraulic circuit. More specifically, the brake actuator 26 has a pressure increasing mode for increasing the pressure, a holding mode for holding the pressure, and a pressure reducing mode for decreasing the pressure as the control mode of the brake hydraulic pressure. The brake actuator 26 can vary the control mode of the brake hydraulic pressure for each wheel 10 by controlling ON / OFF of various electromagnetic valves. The braking force applied to each wheel 10 is determined according to the brake hydraulic pressure supplied to each wheel cylinder 28a. Therefore, the brake actuator 26 can independently control the braking force of each wheel 10 by changing the control mode.

  The braking control device of this embodiment includes an electronic control unit (ECU) 40 on the vehicle 1. Various sensors and the brake actuator 26 are electrically connected to the ECU 40. The various sensors herein include a wheel speed sensor 42, a vehicle speed sensor 44, an acceleration sensor 46, a brake pedaling force sensor 48, and a steering sensor 50. The wheel speed sensor 42 is disposed on each wheel 10 and outputs a wheel speed signal corresponding to the rotational speed of the wheel 10. The vehicle speed sensor 44 outputs a vehicle speed signal corresponding to the vehicle speed (vehicle speed). The acceleration sensor 46 outputs an acceleration signal corresponding to the longitudinal acceleration of the vehicle 1. The brake pedal force sensor 48 outputs a brake pedal force signal corresponding to the pedal force of the brake pedal 22. The steering sensor 50 outputs a steering angle signal corresponding to the rotation angle (steering angle) of the steering wheel 12a.

  The ECU 40 includes a processor, a memory, and an input / output interface. The input / output interface takes in sensor signals from various sensors attached to the vehicle 1 and outputs an operation signal to the brake actuator 26. In the memory, various control programs and maps for controlling the brake actuator 26 are stored. The processor reads the control program from the memory and executes it, thereby realizing the function of the braking control device.

[Brake Control of Embodiment 1]
(Left and right wheel independent control)
FIG. 2 is a conceptual diagram for explaining the left and right wheel independent control according to the first embodiment of the present invention. FIG. 3 is a diagram for explaining an example of adjusting the braking force of the left and right rear wheels 10RL and 10RR by the left and right wheel independent control according to the first embodiment of the present invention, in which the left and right rear wheels 10RL and 10RR are adjusted during braking. The relationship between the longitudinal force (that is, braking force) and the slip ratio S is shown.

  In the present embodiment, “right and left wheel independent control” is used for the left and right rear wheels 10RL and 10RR in order to ensure the braking stability of the vehicle 1. In the left and right wheel independent control, the braking forces of the left and right rear wheels 10RL and 10RR are independently controlled so that the respective slip ratios S of the left and right rear wheels 10RL and 10RR are equal to a predetermined target slip ratio St. .

The slip ratio S of the wheel 10 can be calculated according to the following equation (1) based on the wheel speed Vw detected by the wheel speed sensor 42 and the vehicle body speed V detected by the vehicle speed sensor 44, for example. Note that the vehicle body speed V is replaced with the vehicle speed sensor 44 by using a known method based on, for example, the wheel speed Vw detected by the wheel speed sensor 42 and the deceleration of the vehicle 1 detected by the acceleration sensor 46. May be estimated.

In general, the center of gravity of a vehicle is often shifted in the left-right direction from the center of the vehicle as in the example shown in FIG. FIG. 2 shows a situation where braking is performed in a state where the center of gravity of the vehicle 1 is shifted in the left-right direction. Thus, when the center of gravity of the vehicle 1 is deviated, the ground loads of the left and right wheels 10 are different. If the ground loads on the left and right wheels 10 are different, when the same braking force is applied to the left and right wheels 10, the ground load reducing wheel 10 (in the example shown in FIG. 2, the right front wheel 10FR and the right rear wheel 10RR). Is lower than the wheel speeds of the opposite wheels (the left front wheel 10FL and the left rear wheel 10RL). As a result, as shown by the dashed line in FIG. 3, the same braking force F1 is the left and right rear wheels 10RL, when a given 10RR, vertical load than the slip ratio S _RL of the left rear wheel 10RL of vertical load increasing side decreasing side towards the slip ratio _{S RR} of the right rear wheel 10RR increases of. FIG. 3 shows the characteristics of the left and right rear wheels 10RL and 10RR. The relationship between the left front wheel 10FL and the right front wheel 10FR is the same as that in FIG.

  As described above, even when the braking force of the left and right wheels 10 is the same during braking, a difference occurs in the slip ratio S between the left wheels 10FL, 10RL and the right wheels 10FR, 10RR, and the moment ( The clockwise moment shown in FIG. As a result, as in the example shown in FIG. 2, even when the steered wheel (front wheel 10F) is in the straight traveling position, the vehicle 1 tends to deflect toward the ground load reduction side (right side in FIG. 2).

As described above, when braking is performed in a situation where the ground loads of the left and right wheels 10 are different, the following effects can be obtained by applying the left and right wheel independent control of the present embodiment. Here, as an example of the target slip ratio St of the left and right wheels independently controlled left and right rear wheels 10RL, as shown in FIG. 3, each of the slip ratio _S RL of _10RR, for example a value St1 is used in between _{S RR} Description To do.

In the example shown in FIGS. 2 and 3, the left and right rear wheels 10RL, 10RR are set so that the slip ratio S of the left and right rear wheels 10RL, 10RR is equal to the target slip ratio St1 by executing the left and right wheel independent control. The braking force is controlled independently. As a result, the braking force of the left rear wheel 10RL, which is the wheel on the contact load increasing side (that is, the outside of the turn due to the moment based on the gravity offset), is increased from F1 to _FRL in order to increase the slip ratio S. On the other hand, the ground contact load decreases side (i.e., inside of the turn) braking force of the right rear wheel 10RR is a wheel is reduced to F _RR from F1 to reduce the slip ratio S.

  According to the left and right wheel independent control, as described above, the braking force of the left rear wheel 10RL on the contact load increasing side is increased more than the braking force of the right rear wheel 10RR on the contact load decreasing side. A difference is given to the braking force of 10RR. As a result, a moment (a counterclockwise moment shown in FIG. 2) is generated in the vehicle 1 due to the left-right difference in the braking force. This moment acts as a yaw moment (so-called anti-spin moment) for canceling the moment due to the gravity offset. Thereby, the braking stability of the vehicle 1 can be improved. The left and right wheel independent control described above corresponds to one of EBD (Electronic Brake force Distribution) which appropriately controls the braking force distribution to each wheel 10 according to the situation of the vehicle 1.

As can be seen from the characteristics shown in FIG. 3, the braking force of the wheel (10RL) on the ground load increasing side is reduced on the ground load decreasing side even when compared with any slip ratio S other than the target slip ratio St1. It becomes larger than the braking force of the wheel (10RR). Accordingly, the target slip ratio St used for left and right wheels independently control the slip ratio S _RL as _St1, not limited to the values between S _RR, may be used is larger than the slip ratio S _RR, Conversely, a value smaller than the slip ratio _SRL may be used.

(Characteristic control of Embodiment 1)
As in the example described with reference to FIGS. 2 and 3, the slip ratio S of each wheel 10 is likely to fluctuate transiently at the initial stage of braking performed in a situation where the ground loads of the left and right wheels 10 are different. Become. If the left and right wheel independent control described above is performed at the beginning of such braking, there is a concern that the left and right wheel independent control may adversely affect the braking stability of the vehicle 1. More specifically, when the left and right wheel independent control is started early in order to correct an early change in the slip ratio S of each wheel 10 in the early stage of braking, the behavior of the vehicle 1 is stabilized due to factors such as control variations. May be difficult to converge.

  Therefore, in this embodiment, when the predetermined start condition A for the left and right wheel independent control is satisfied, the right and left wheel independent control is not started immediately after the start condition A is satisfied, but instead the right and left wheel independent control is started. Prior to this, the left and right wheel common control is executed. Here, the left and right wheel common control is to control the braking force so that the braking forces of the left and right rear wheels 10RL and 10RR are equal.

(Processing by ECU)
FIG. 4 is a flowchart that shows a routine that is executed by the ECU 40 in order to implement the braking control according to the first embodiment of the present invention. Note that this routine is repeatedly executed at a predetermined cycle after the vehicle 1 is started.

  In the routine shown in FIG. 4, the ECU 40 first calculates the slip ratio S to the wheel 10 using the wheel speed signal of the wheel speed sensor 42 of each wheel 10, the vehicle body speed signal of the vehicle speed sensor 44, and the above equation (1). It is calculated every time (step 100).

  Next, the ECU 40 determines whether or not a predetermined start condition A for left and right wheel independent control is satisfied (step 102). For example, the start condition A is that the deceleration of the vehicle 1 based on the acceleration signal of the acceleration sensor 46 is a predetermined value (for example, 0.4 G) or more.

  If the ECU 40 determines in step 102 that the start condition A is not satisfied, the ECU 40 immediately ends the current processing cycle. In this case, the brake hydraulic pressure corresponding to the depression force of the brake pedal 22 is supplied to the wheel cylinders 28 a of the wheels 10. More specifically, the wheel cylinder 28a of each wheel 10 is provided with the same braking force with respect to the left and right directions of the front wheel 10F and the rear wheel 10R so as to obtain a braking force according to a predetermined front-rear distribution. Thus, the brake hydraulic pressure adjusted by the brake actuator 26 is supplied.

  On the other hand, when it is determined in step 102 that the start condition A is satisfied, the ECU 40 determines whether or not an elapsed time T1 from the time when the start condition A is satisfied exceeds a predetermined time Tth1 (step 104). As described above, the slip ratio S of each wheel 10 tends to fluctuate transiently at the initial stage of braking performed when the ground contact loads of the left and right wheels 10 are different. The predetermined time Tth1 used as an example in the present step 104 corresponds to a time (for example, 150 ms) necessary for averaging the fluctuation of the slip ratio S that is sequentially calculated every cycle (for example, 6 ms) of this routine. .

  If it is determined in step 104 that the elapsed time T1 has not yet exceeded the predetermined time Tth1, the ECU 40 executes the left and right wheel common control as control of the braking force of the left and right rear wheels 10RL and 10RR (step 106). As an example of the left and right wheel common control, in this step 106, the control of holding the braking force of the left and right rear wheels 10RL and 10RR with the same left and right braking force applied to the left and right rear wheels 10RL and 10RR when the start condition A is satisfied. Is executed.

  On the other hand, when it is determined in step 104 that the elapsed time T1 has exceeded the predetermined time Tth1, the ECU 40 executes left and right wheel independent control as control of the braking force of the left and right rear wheels 10RL and 10RR (step 108). More specifically, in the left and right wheel independent control, the slip ratio deviation ΔS with respect to the target slip ratio St of the slip ratio S of each of the left and right rear wheels 10RL and 10RR is calculated. As the target slip ratio St, for example, a value determined in advance can be used. As the slip ratio S of each of the left and right rear wheels 10RL, 10RR, a value obtained by averaging the values sequentially calculated by the processing of step 100 within a certain time (here, 150 ms described above) is used as an example. Is done.

  In addition, according to the left and right wheel independent control, the brake hydraulic pressure supplied to the wheel cylinder 28a is decreased in the rear wheel 10R on the side where the slip ratio S is higher than the target slip ratio St. The braking force is reduced. On the other hand, in the rear wheel 10R where the slip ratio S is lower than the target slip ratio St, in order to increase the slip ratio S, the brake hydraulic pressure supplied to the wheel cylinder 28a is increased, that is, the braking force is increased. When the slip ratio S is equal to (or substantially equal to) the target slip ratio St, the brake hydraulic pressure supplied to the wheel cylinder 28a is maintained, that is, the braking force is maintained. For example, the brake hydraulic pressure adjustment amount (increase / decrease amount) based on the slip rate deviation ΔS is increased as the slip rate deviation ΔS increases.

  According to the left and right wheel independent control, the feedback control as described above is performed. As a result, the braking forces of the left and right rear wheels 10RL and 10RR can be controlled independently so that the respective slip ratios S of the left and right rear wheels 10RL and 10RR are equal to the target slip ratio St.

  As described above, according to the routine shown in FIG. 4, when the start condition A for the left and right wheel independent control is satisfied, the right and left wheel independent control is not started immediately after the start condition A is satisfied. Prior to the start of the wheel independent control, the left and right wheel common control is executed. In other words, immediately after the start condition A is satisfied, a process for delaying the start of the left and right wheel independent control is performed by performing the left and right wheel common control. As a result, the right and left wheel independent control is prevented from intervening immediately at the beginning of braking, and the left and right wheel independent control can be started after the stable slip ratio S is obtained. For this reason, it becomes possible to perform the left and right wheel independent control while improving the robustness against disturbances such as control variations. As a result, high braking stability of the vehicle 1 can be ensured.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG. In the following description, the configuration shown in FIG. 1 is used as an example of the system configuration of the second embodiment.

[Brake Control of Embodiment 2]
The braking control of the present embodiment is different from the braking control of the first embodiment in the content of the left and right wheel common control executed after the start condition A of the left and right wheel independent control is satisfied.

  More specifically, in the left and right wheel common control according to the first embodiment, the left and right rear wheels 10RL and 10RR have the same braking force applied to the left and right rear wheels 10RL and 10RR when the start condition A is satisfied. Is retained. On the other hand, in the left and right wheel common control of this embodiment, when there is a request to reduce one braking force of the left and right rear wheels 10RL and 10RR, the braking forces of both the left and right rear wheels 10RL and 10RR are made equal according to the request. Decrease control is executed. That is, a control (so-called low select control (also referred to as select low control)) is performed in which the brake hydraulic pressure supplied to the wheel cylinders 28a of the left and right rear wheels 10RL and 10RR is made equal to the low pressure side pressure.

(Processing by ECU)
FIG. 5 is a flowchart that shows a routine that is executed by the ECU 40 in order to implement the braking control according to the second embodiment of the present invention. The processing in steps 100 to 104 and 108 in the routine shown in FIG. 5 is as described in the first embodiment.

  In this routine, if the ECU 40 determines in step 104 that the elapsed time T1 has not yet exceeded the predetermined time Tth1, the ECU 40 proceeds to step 200. In step 200, left and right wheel common control (low select control) is executed.

  According to the left and right wheel common control in step 200, when the higher value of the slip ratios S of the left and right rear wheels 10RL and 10RR sequentially calculated in step 100 exceeds a predetermined value, Processing is executed. In other words, the brake hydraulic pressure supplied to the wheel cylinder 28a of the rear wheel 10R on the high slip ratio side is decreased by a predetermined amount, and the brake hydraulic pressure supplied to the wheel cylinder 28a of the other rear wheel 10R is similarly decreased by a predetermined amount. A decrementing process is executed. As a result, the braking forces of the left and right rear wheels 10RL, 10RR are aligned with the value of the rear wheel 10R on the low wheel speed side (high slip ratio side), that is, the lower value.

  Also by the routine shown in FIG. 5 described above, when the start condition A for the left and right wheel independent control is satisfied, the left and right wheel common control is executed prior to the start of the left and right wheel independent control. As a result, the right and left wheel independent control is prevented from intervening immediately at the beginning of braking, and the left and right wheel independent control can be started after the stable slip ratio S is obtained.

  In addition, in the routine shown in FIG. 5, the above-described low select control is executed as the left and right wheel common control executed prior to the left and right wheel independent control. According to the low select control, as described above, the braking forces of the left and right rear wheels 10RL, 10RR are aligned with the value of the rear wheel 10R on the low wheel speed side (high slip ratio side), that is, the lower value. As a result, the braking stability of the vehicle 1 at the initial stage of braking before the start of the left and right wheel independent control is improved as compared with the control of the first embodiment, and the left and right wheel independent control can be performed thereafter.

  In the first and second embodiments described above, when the start condition A is satisfied, the left and right wheel common control is based on whether or not the elapsed time T1 from the time when the start condition A is satisfied exceeds a predetermined time Tth1. Alternatively, left and right wheel independent control is selected. However, the process for determining the initial braking where the slip ratio S of each wheel 10 changes transiently can appropriately delay the start of the left and right wheel independent control with respect to the time when the start condition A is satisfied. For example, the present invention is not limited to the example using the elapsed time T1. That is, for example, an example described below may be used.

The braking start time may be detected based on the brake pedal force signal of the brake pedal force sensor 48, and the left and right wheel common control may be executed until the elapsed time T2 from the braking start time exceeds the predetermined time Tth2. The predetermined time Tth2 is a threshold value for determining the elapsed time T2 that will be required from the start of braking until the load change of each wheel 10 settles.
Further, when it is detected that the steering wheel 12a is operated when the start condition A is satisfied based on the steering angle signal of the steering sensor 50, the elapsed time T3 from the steering start time exceeds the predetermined time Tth3. Until then, the left and right wheel common control may be executed. The predetermined time Tth3 is a threshold value for determining an elapsed time T3 that will be required from the start of steering until the operation of the steering wheel 12a is stabilized.
Further, based on the acceleration signal of the acceleration sensor 46, the time point at which the change in the deceleration of the vehicle 1 has stopped after the start condition A is satisfied is detected, and both the left and right wheels are common until the elapsed time T4 from this point exceeds the predetermined time Tth4. You may make it perform control. The predetermined time Tth4 is a threshold value for determining the elapsed time T4 that will be required until the change in the slip ratio S of each wheel 10 is settled after the start of braking.
Note that the determination examples using the elapsed times T1 to T4 may be used in appropriate combination.

  In the first embodiment described above, as the left and right wheel common control executed immediately after the start condition A is satisfied, the left and right rear wheels 10RL and 10RR are applied with the same left and right braking force when the start condition A is satisfied. In the second embodiment, row select control is executed. However, the left and right wheel common control that is the subject of the present invention is not limited to the above-described one, and may be, for example, the following control. That is, in contrast to the above-described low select control, control for adjusting the brake hydraulic pressure supplied to the wheel cylinders 28a of the left and right rear wheels 10RL, 10RR to the high pressure side (so-called high select control (also referred to as select high control)) May be executed as the left and right wheel common control. In addition, according to the low select control, a characteristic that gives more importance to the braking stability of the vehicle 1 can be obtained, whereas according to the high select control, a characteristic that gives more importance to the braking performance of the vehicle 1 can be obtained.

  Further, in the left and right wheel independent control of the first and second embodiments described above, the slip ratio S is used as an example of the slip degree. However, the left and right wheel independent control according to the present invention may be any control that independently controls the braking force of the left and right rear wheels so that the respective slip degrees of the left and right rear wheels are equal to the target slip degree. Instead, for example, a slip amount (that is, a difference obtained by subtracting the wheel speed Vw from the vehicle body speed V) may be used as the slip degree.

  Moreover, in Embodiment 1 and 2 mentioned above, the brake device 20 which can control the braking force of the four wheels 10 of the vehicle 1 independently was mentioned as an example. However, the braking control according to the present invention can be applied to a vehicle including a braking device that can independently control at least the braking forces of the left and right rear wheels.

1 Vehicle 10 Wheel 10F Front Wheel 10FL Left Front Wheel 10FR Right Front Wheel 10R Rear Wheel 10RL Left Rear Wheel 10RR Right Rear Wheel 12 Steering Device 12a Steering Wheel 20 Brake Device 22 Brake Pedal 24 Master Cylinder 26 Brake Actuator 28 Brake Mechanism 28a Wheel Cylinder 30 Hydraulic Piping 40 Electronic Control Unit (ECU)
42 Wheel speed sensor 44 Vehicle speed sensor 46 Acceleration sensor 48 Brake pedal force sensor 50 Steering sensor

Claims (2)

A vehicle braking control device including a braking device capable of independently controlling the braking force of the left and right rear wheels,
In the braking force control performed by the braking control device, the left and right rear wheel common control for controlling the braking force so that the braking forces of the left and right rear wheels are equal, and the respective slip degrees of the left and right rear wheels are equal to the target slip degree. Left and right wheel independent control to independently control the braking force of the left and right rear wheels,
The brake control device is configured to execute the left and right wheel common control prior to the start of the left and right wheel independent control when the start condition of the left and right wheel independent control is satisfied. Braking control device.   The left and right wheel common control performed upon establishment of the start condition, when there is a request to reduce the braking force of one of the left and right rear wheels, equally reduces the braking force of both the left and right rear wheels according to the request. The vehicle braking control device according to claim 1, wherein the vehicle braking control device is a control for controlling the vehicle.

Images