Brake control device

Abstract

To provide a technique which prevents an occupant from feeling discomfort and can achieve desired control early if a brake device is in a low-temperature state in a brake control device which controls a vehicle attitude by controlling brake force applied on each wheel.SOLUTION: In a brake control device 26, a control part 34 independently controls brake force applied on each wheel of a vehicle by a brake device from when an interposition condition is satisfied when the vehicle is turned until when an interposition termination condition is satisfied, and then controls a yaw moment and a roll moment. A change part 36 executes at least one of changing of the interposition condition so as to make them easy to be satisfied and changing of the interposition termination condition so as to make them hard to be satisfied in a case in which the brake device is in a low-temperature state, in comparison with a case in which the brake device is in a non-low-temperature state.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a braking control device. [Background technology]

[0002] Patent Document 1 discloses a vehicle braking control device that can prevent a decrease in braking performance when the friction brake is cold. This technology applies a strong force to the friction brake when the driver requests deceleration of the vehicle and the estimated temperature of the friction brake is determined to be below a set value or when the friction brake has not been used for a predetermined period of time. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-199814 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a known technology for controlling the yaw moment and roll moment during vehicle cornering by independently controlling the braking force applied to each wheel of a vehicle. With this technology, the sum of the braking forces applied to each wheel is converted into a very small value for longitudinal acceleration, so that the occupants are virtually unaware that braking force is being applied while the vehicle is cornering. With this technology, when the braking system is cold, the friction coefficient of the brake pads decreases, reducing braking force. The viscosity of the brake fluid also increases, making it difficult to ensure the desired hydraulic response, potentially resulting in an inability to achieve the desired control performance. Therefore, it is desirable to quickly warm the brake pads and other components when the braking system is cold.

[0005] However, the inventors recognized that when the braking force is increased in low-temperature conditions to accelerate temperature rise as in the technology of Patent Document 1, if the braking force and hydraulic responsiveness increase in response to the temperature rise of the brake pads, etc., the occupant may be more likely to notice that braking force is being applied while the vehicle is turning, which may cause discomfort to the occupant. It is difficult to increase the braking force to an extent that makes it difficult for the occupant to notice that braking force is being applied while maintaining robustness.

[0006] The object of the present invention is to provide a technology for a braking control device that controls the braking force applied to each wheel to control the vehicle posture, which can achieve desired control early and without causing discomfort to occupants when the braking device is in a low temperature state. [Means for solving the problem]

[0007] In order to solve the above problem, a braking control device of one embodiment of the present invention includes a control unit that controls the yaw moment and roll moment by independently controlling the braking force applied to each wheel of the vehicle by the braking device from the time an intervention condition is satisfied until an intervention termination condition is satisfied when the vehicle is turning, and a modification unit that performs at least one of changing the intervention condition to be more easily satisfied and changing the intervention termination condition to be more difficult to satisfy when the braking device is in a low-temperature state compared to when the braking device is not in a low-temperature state. [Effects of the Invention]

[0008] According to the present invention, in a braking control device that controls the braking force applied to each wheel to control the vehicle posture, when the braking device is in a low temperature state, the desired control can be achieved early without causing discomfort to the occupants. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing a schematic configuration of a vehicle according to an embodiment; [Figure 2] FIG. 2 is a diagram showing a functional configuration of the braking control device of FIG. [Figure 3]FIG. 10 is a diagram showing the relationship between the first angular velocity threshold and the vehicle body speed before and after the change. [Figure 4] FIG. 4 is a diagram showing the relationship between the friction coefficient of a brake pad and the temperature of brake fluid. [Figure 5] 3 is a flowchart showing a process for changing an intervention condition of the braking control device of FIG. 2. [Figure 6] 10 is a flowchart showing another process for changing the intervention condition of the braking control device of FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the description, the same elements are denoted by the same reference numerals, and duplicate descriptions will be omitted as appropriate.

[0011] 1 shows a schematic configuration of a vehicle 1 according to an embodiment. The vehicle 1 includes a left front wheel 2fL, a right front wheel 2fR, a left rear wheel 2rL, a right rear wheel 2rR, and a vehicle control system 10. Hereinafter, unless there is a particular need to distinguish between them, the left front wheel 2fL, the right front wheel 2fR, the left rear wheel 2rL, and the right rear wheel 2rR will be collectively referred to as wheels 2.

[0012] The vehicle 1 may be a vehicle that generates vehicle driving force only by an internal combustion engine, or may be an electrically powered vehicle. The electrically powered vehicle may be a hybrid electric vehicle (HEV) that generates vehicle driving force using an internal combustion engine and a motor, or may be an electric vehicle (BEV: Battery Electric Vehicle) or a fuel cell electric vehicle (FCEV: Fuel Cell Electric Vehicle) that generates vehicle driving force only by a motor.

[0013] The vehicle control system 10 can independently control the braking force of each of the four wheels of the vehicle 1 based on a driver input. The driver input includes the driver's accelerator operation, brake operation, and steering.

[0014] The vehicle control system 10 includes a steering device 12, a steering angle sensor 14, an accelerator pedal sensor 16, a brake pedal sensor 18, a vehicle speed sensor 20, a brake fluid temperature sensor 22, a braking device 24, and a braking control device 26.

[0015] The steering device 12 steers the left front wheel 2fL and the right front wheel 2fR, which are steerable wheels, in response to the operation of the steering wheel of the vehicle 1 by the driver.

[0016] The steering angle sensor 14 detects the amount of operation of the steering wheel of the vehicle 1 by the driver, and supplies the detected amount of operation to the braking control device 26. The amount of operation of the steering wheel is the steering angle.

[0017] Accelerator pedal sensor 16 is provided on the accelerator pedal of vehicle 1, detects the amount of accelerator pedal operation by the driver, and supplies the detected amount of operation to braking control device 26. The amount of accelerator pedal operation is, for example, the amount of accelerator pedal depression by the driver.

[0018] The brake pedal sensor 18 is provided on the brake pedal of the vehicle 1, detects the amount of brake pedal operation by the driver, and supplies the detected amount of operation to the braking control device 26. The amount of brake pedal operation is, for example, the amount of depression of the brake pedal by the driver.

[0019] The vehicle speed sensor 20 detects the vehicle speed of the vehicle 1 and supplies the detected vehicle speed to the braking control device 26 .

[0020] The braking device 24 has a left front disc brake unit 3fL, a right front disc brake unit 3fR, a left rear disc brake unit 3rL, a right rear disc brake unit 3rR, and a brake actuator 28. The braking device 24 may have a known configuration.

[0021] Hereinafter, unless there is a particular need to distinguish between them, the left front disc brake unit 3fL, the right front disc brake unit 3fR, the left rear disc brake unit 3rL, and the right rear disc brake unit 3rR will be collectively referred to as the disc brake unit 3.

[0022] The brake actuator 28 applies a braking force to each wheel 2 of the vehicle 1 according to the amount of depression of the brake pedal. The brake actuator 28 is controlled by a control signal supplied from the brake control device 26, and can apply a braking force independently to each wheel 2 of the vehicle 1. The brake actuator 28 is connected to each disc brake unit 3 by individual brake piping, and can independently adjust the hydraulic pressure of the brake fluid supplied to each disc brake unit 3. The brake piping may be a so-called two-system system, front and rear, or a two-system system, X-piping.

[0023] Each disc brake unit 3 has a caliper, a brake disc, and brake pads (not shown). A wheel cylinder (not shown) built into the caliper is connected to a brake actuator 28 via a brake pipe, and the hydraulic pressure of the brake fluid supplied from the brake actuator 28 presses the brake pads against the brake disc that rotates together with the wheel 2, thereby applying a braking force to the wheel 2.

[0024] The brake fluid temperature sensor 22 is disposed in the brake actuator 28 to detect the temperature of the brake fluid and to supply the detected temperature to the brake control device 26 .

[0025] The braking control device 26 individually controls the braking force applied to each wheel 2 by the braking device 24 based on the detected operation amount, for example, while the vehicle 1 is turning, thereby controlling the yaw moment and roll moment of the vehicle 1 and controlling the attitude of the vehicle 1. The braking control device 26 can be configured with an ECU (Electronic Control Unit).

[0026] The vehicle control system 10 may include at least one of a drive actuator that controls the vehicle driving force of the vehicle 1, an actuator such as an active suspension that controls the vertical force of the vehicle 1, and a steering actuator that controls the lateral force of the vehicle 1. In this case, the braking control device 26 may also control these actuators based on the detected operation amount, and may function as a vehicle control device that controls the attitude of the vehicle 1.

[0027] Fig. 2 shows the functional configuration of the braking control device 26 of Fig. 1. The braking control device 26 has a derivation unit 30, an intervention determination unit 32, a control unit 34, a change unit 36, a timer unit 38, and an integrating unit 40.

[0028] The configuration of the braking control device 26 can be realized in hardware terms by the CPU, memory, and other LSI of any computer, and in software terms by programs loaded into memory, but here we depict functional blocks realized by the cooperation of these. Therefore, it will be understood by those skilled in the art that these functional blocks can be realized in various forms using only hardware, only software, or a combination of both.

[0029] The derivation unit 30 periodically derives the longitudinal force at the position of each wheel 2 based on the driver's operation input, and periodically supplies the derived longitudinal force to the control unit 34. The longitudinal force of each wheel 2 is a target longitudinal force, and corresponds to the braking force to be generated in each disc brake unit 3.

[0030] For example, the derivation unit 30 periodically derives the six center-of-gravity components based on the detected accelerator pedal operation amount, the detected brake pedal operation amount, the detected steering angle, and a predetermined vehicle motion model. The six center-of-gravity components include longitudinal forces, lateral forces, vertical forces, roll moments, pitch moments, and yaw moments acting on the center of gravity of the sprung structure of the vehicle 1. The derivation unit 30 periodically derives the longitudinal forces at the position of each wheel 2 based on the derived six center-of-gravity components.

[0031] Since various known techniques can be used to derive the longitudinal force of each wheel 2 based on the driver's operation input, further detailed explanation will be omitted. For example, the longitudinal force may be derived using the technique described in JP 2022-21715 A.

[0032] The intervention determination unit 32 periodically determines whether the intervention condition is satisfied and supplies the determination result to the control unit 34. The intervention condition includes that the steering angular velocity is equal to or greater than a first angular velocity threshold. For example, the higher the vehicle body speed, the smaller the first angular velocity threshold.

[0033] When the intervention condition is satisfied, the intervention determination unit 32 periodically determines whether the intervention end condition is satisfied, and supplies the determination result to the control unit 34. The intervention end condition includes that the steering angular velocity is less than a second angular velocity threshold value, or that the elapsed time since the intervention condition was satisfied reaches a predetermined end time.

[0034] The second angular velocity threshold is smaller than the first angular velocity threshold. In other words, the threshold for the steering angular velocity has hysteresis. For example, the second angular velocity threshold may be smaller than the first angular velocity threshold by a constant value. The constant value can be determined appropriately through experiments or simulations.

[0035] The intervention determination unit 32 has a control timer (not shown), which starts counting the elapsed time when the intervention condition is satisfied. The intervention determination unit 32 determines that the intervention end condition is satisfied when the steering angular velocity becomes less than the second angular velocity threshold before the elapsed time reaches a predetermined end time. The intervention determination unit 32 also determines that the intervention end condition is satisfied when the elapsed time reaches the end time before the steering angular velocity becomes less than the second angular velocity threshold. The end time can be determined as appropriate through experiments or simulations.

[0036] The intervention condition may include that the steering angular velocity is equal to or greater than a first angular velocity threshold, the vehicle body speed is equal to or greater than a first vehicle speed threshold, and the steering angle is equal to or greater than a first steering angle threshold. In this case, the intervention termination condition may include that the steering angular velocity is less than a second angular velocity threshold, the vehicle body speed is less than a second vehicle speed threshold, the steering angle is less than a second steering angle threshold, or the elapsed time since the intervention condition was satisfied reaches the termination time. The second vehicle speed threshold may be smaller than the first vehicle speed threshold. The second steering angle threshold may be smaller than the first steering angle threshold. In other words, the threshold related to the vehicle body speed and the threshold related to the steering angle each have hysteresis. Various other known conditions may be used as the intervention condition and the intervention termination condition.

[0037] The control unit 34 independently controls the braking force applied to each wheel 2 by the braking device 24 based on the longitudinal force of each wheel 2 periodically supplied from the derivation unit 30 from the time the intervention condition is satisfied when the vehicle 1 turns until the intervention termination condition is satisfied, thereby controlling the yaw moment and roll moment.

[0038] The control unit 34 realizes vehicle control according to the driver's input by transmitting a control command to the brake actuator 28 based on the longitudinal force of each wheel 2 derived by the derivation unit 30. The control unit 34 converts the derived longitudinal force of each wheel 2 into a control command for the brake actuator 28, for example.

[0039] In this way, for example, when the driver steers and the vehicle 1 turns, the braking control device 26 automatically controls the braking force applied to each wheel 2, so that the yaw moment approaches the target yaw moment derived by the derivation unit 30, and the roll moment approaches the target roll moment derived by the derivation unit 30, thereby controlling the attitude of the vehicle 1 during the turn.

[0040] The change unit 36 periodically determines whether the braking device 24 is in a low temperature state based on the elapsed time since the vehicle 1 became drivable, the temperature of the brake fluid in the braking device 24, and the integrated value of heat energy generated in the brake pads of the braking device 24 since the vehicle 1 became drivable. Specific conditions for the determination will be described later.

[0041] When it is determined that the braking device 24 is in a low temperature state, the change unit 36 performs at least one of changing the intervention condition to make it easier to satisfy and changing the intervention termination condition to make it harder to satisfy compared to when it is determined that the braking device 24 is in a non-low temperature state.

[0042] Changing the intervention condition to make it more likely to be met includes changing the first angular velocity threshold to a smaller value.

[0043] FIG. 3 shows the relationship between the first angular velocity threshold and the vehicle speed before and after the change. The first angular velocity threshold before the change is shown by a dashed line, and the first angular velocity threshold after the change is shown by a solid line. As shown in FIG. 3, the lower the vehicle speed, the larger the first angular velocity threshold, and the higher the vehicle speed, the smaller the first angular velocity threshold. The first angular velocity threshold before the change is used when the braking device 24 is not in a low-temperature state. The first angular velocity threshold after the change is used when the braking device 24 is in a low-temperature state, and is smaller than the first angular velocity threshold before the change.

[0044] The relationship between the first angular velocity threshold value and the vehicle body speed before and after the change is stored in advance in a storage unit (not shown). The relationship between the first angular velocity threshold value and the vehicle body speed before and after the change can be determined appropriately through experiments or simulations. For example, the changed first angular velocity threshold value may be a value obtained by subtracting a predetermined value from the changed first angular velocity threshold value.

[0045] Furthermore, changing the intervention end condition to make it more difficult to satisfy includes at least one of changing the second angular velocity threshold to be smaller and changing the end time of the control timer to be longer.

[0046] The changed second angular velocity threshold is smaller than the changed first angular velocity threshold. In other words, the threshold for the steering angular velocity has hysteresis even after the change. For example, the changed second angular velocity threshold may be smaller than the changed first angular velocity threshold by a constant value. If the pre-change second angular velocity threshold is smaller than the changed first angular velocity threshold, the second angular velocity threshold does not need to be changed.

[0047] It can also be said that when it is determined that the braking device 24 is in a low temperature state, the modification unit 36 modifies at least one of the intervention condition and the intervention termination condition so that the execution time of the braking force control during a certain period of time while the vehicle is turning is longer than when it is determined that the braking device 24 is in a non-low temperature state.

[0048] When the braking device 24 changes from a low temperature state to a non-low temperature state, the change unit 36 returns the changed condition out of the intervention condition and the intervention termination condition to the original condition.

[0049] In this way, when the braking device 24 is in a low temperature state, the intervention condition is changed to be more likely to be satisfied than when the braking device 24 is not in a low temperature state, which makes it more likely that the control unit 34 will start controlling the braking force, and increases the frequency of intervention in braking force control. This allows the temperature of the brake pads and brake fluid to rise more quickly, which in turn speeds up the increase in the friction coefficient of the brake pads and the improvement in the hydraulic response of the brake fluid. Therefore, desired vehicle control can be performed earlier.

[0050] Furthermore, when the braking device 24 is in a low temperature state, the intervention termination condition is changed to be less likely to be satisfied compared to when the braking device 24 is not in a low temperature state, which increases the time for which the control unit 34 controls the braking force. This also makes it possible to speed up the temperature rise of the brake pads and brake fluid, enabling the desired vehicle control to be performed earlier.

[0051] When the braking device 24 is in a low temperature state, the intervention condition is changed to be more likely to be met and the intervention termination condition is changed to be less likely to be met, thereby making it possible to speed up the temperature rise of the brake pads and brake fluid.

[0052] Even in a low temperature state, the target longitudinal force derived by the derivation unit 30, i.e., the target braking force, is not changed, so it is difficult for the occupants to realize that braking force is being applied by the brake control device 26 while the vehicle 1 is turning, and it is possible to reduce the discomfort felt by the occupants. This is because even if the braking force increases in response to an increase in the temperature of the brake pads, the target braking force is the same as the value assumed in a non-low temperature state.

[0053] Next, a description will be given of the determination of whether the braking device 24 is in a low temperature state. The timer unit counts the elapsed time Ts since the vehicle 1 became in a drivable state, and supplies the elapsed time Ts to the change unit .

[0054] In the case of a vehicle 1 that generates vehicle driving force solely through an internal combustion engine, the vehicle 1 becoming ready to run corresponds to the internal combustion engine starting. In the case of an electrically powered vehicle, the vehicle 1 becoming ready to run corresponds to the ignition switch being turned from off to on, and the driving system (not shown) changing from a stopped state to a running state. The ignition switch is also called a start switch. The running state is also called a Ready-ON state.

[0055] The accumulating unit 40 periodically derives an integrated value σJb of heat generation energy in the four brake pads of the braking device 24 after the vehicle 1 has entered a drivable state, and supplies the derived integrated value σJb to the changing unit 36. The heat generation energy includes energy generated by braking force controlled by the control unit 34 while the vehicle is turning, and energy generated by braking force corresponding to the amount of depression of the brake pedal. For example, the accumulating unit 40 periodically executes the following series of processes.

[0056] First, the integrating unit 40 derives the heat energy Qin_i per unit time in the brake pad of each wheel 2 according to the following equation (1).

[0057] Qin_i=(μi·Aci·ri / Rdi)·Pci·Vwi [J / sec / ring] Formula (1)

[0058] i is an integer between 1 and 4. For example, i=1 indicates a value related to the left front wheel 2fL, i=2 indicates a value related to the right front wheel 2fR, i=3 indicates a value related to the left rear wheel 2rL, and i=4 indicates a value related to the right rear wheel 2rR.

[0059] μi represents the friction coefficient of the brake pad of each wheel 2. Aci represents the cylinder area of each wheel 2. ri represents the effective braking radius of each wheel 2. Pci represents the cylinder pressure of each wheel 2. Rdi represents the dynamic tire load radius of each wheel 2. Vwi represents the wheel speed of each wheel 2.

[0060] Next, the integrating unit 40 derives the sum of the heat energy Qin_i per unit time in the brake pads of the four wheels 2, which is expressed by the following equation (2).

[0061] Σ Qin_i i=1~4 [J / sec] Equation (2)

[0062] Next, the integrating unit 40 derives the current sum of the products of the sum of equation (2) and the sampling time Δt as the integrated value σJb of heat energy in the brake pad, as shown in the following equation (3).

[0063] σJb=Σ(Σ Qin_i)Δt [J] Equation (3)

[0064] The friction coefficient μi of the brake pad of each wheel 2 may be a constant value or may be a value that changes depending on the temperature of the brake fluid.

[0065] Fig. 4 shows the relationship between the friction coefficient of the brake pad and the temperature of the brake fluid. The relationship shown in Fig. 4 may be stored in advance in a storage unit (not shown), and the integration unit 40 may acquire the friction coefficient μi of the brake pad determined based on this relationship and the detected temperature of the brake fluid. This allows the integrated value σJb of heat generation energy to be derived more accurately.

[0066] The cylinder pressure Pci of each wheel 2 may be detected by a sensor (not shown) or may be estimated by a known method. The wheel speed Vwi of each wheel 2 may be detected by a sensor (not shown) or may be estimated by a known method.

[0067] When the ignition switch is turned from on to off, the timer unit 38 initializes the elapsed time to zero, and the integrating unit 40 initializes the integrated value σJb of heat generation energy to zero.

[0068] The change unit 36 acquires the detected brake fluid temperature Thf. If the elapsed time Ts is equal to or less than the time threshold value Th1 and the brake fluid temperature Thf is equal to or less than the temperature threshold value Th2, or if the elapsed time Ts is equal to or less than the time threshold value Th1 and the integrated value σJb of the heat generation energy is equal to or less than the integrated value threshold value Th3, the change unit 36 determines that the braking device 24 is in a low-temperature state. The fact that the braking device 24 is in a low-temperature state can also be said to mean that the vehicle 1 including the braking device 24 is in a warm-up state.

[0069] The change unit 36 determines that the braking device 24 is in a non-low temperature state when the elapsed time Ts is greater than the time threshold value Th1. The change unit 36 also determines that the braking device 24 is in a non-low temperature state when the brake fluid temperature Thf is greater than the temperature threshold value Th2 and the integrated value σJb of the heat generation energy is greater than the integrated value threshold value Th3.

[0070] The time threshold value Th1, the temperature threshold value Th2, and the integrated value threshold value Th3 can be determined appropriately through experiments or simulations.

[0071] In this way, by making a determination based on the elapsed time Ts, the temperature Thf of the brake fluid, and the integrated value σJb of the heat generation energy, it is possible to appropriately determine whether the braking device 24 is in a low temperature state.

[0072] The change unit 36 may further determine whether the braking device 24 is in a low temperature state based on the outside air temperature and the off time, which is the time from when the ignition switch is turned off until when it is turned on.

[0073] For example, the change unit 36 may determine that the braking device 24 is in a low temperature state if the outside air temperature is equal to or lower than the outside air temperature threshold, the off time is equal to or higher than the off time threshold, the elapsed time Ts is equal to or lower than the time threshold Th1, and the brake fluid temperature Thf is equal to or lower than the temperature threshold Th2. The change unit 36 may determine that the braking device 24 is in a low temperature state if the outside air temperature is equal to or lower than the outside air temperature threshold, the off time is equal to or higher than the off time threshold, the elapsed time Ts is equal to or lower than the time threshold Th1, and the integrated value σJb of heat generation energy is equal to or lower than the integrated value threshold Th3. The outside air temperature threshold and the off time threshold can be determined as appropriate through experiments or simulations. This can facilitate improving the accuracy of determining that the braking device 24 is in a low temperature state.

[0074] Fig. 5 is a flowchart showing the process of changing the intervention condition of the braking control device 26 of Fig. 2. The process of Fig. 5 is repeatedly executed.

[0075] If the vehicle 1 is not in a drivable state (N in S10), the braking control device 26 ends the process. If the vehicle 1 is in a drivable state (Y in S10), the change unit 36 acquires the elapsed time Ts since the vehicle 1 became drivable (S12), and acquires the temperature Thf of the brake fluid (S14). The integration unit 40 derives an integrated value σJb of the heat energy of the brake pads (S16).

[0076] If the elapsed time Ts is equal to or less than the time threshold value Th1 (Y in S18), if the brake fluid temperature Thf is equal to or less than the temperature threshold value Th2, or if the integrated value σJb of the heat generation energy is equal to or less than the integrated value threshold value Th3 (Y in S20), the change unit 36 changes the intervention condition (S22), and the braking control device 26 ends the processing.

[0077] If the elapsed time Ts is greater than the time threshold value Th1 (N in S18), and the intervention condition has already been changed (Y in S24), the change unit 36 restores the intervention condition (S26), and the braking control device 26 ends the process.

[0078] If the brake fluid temperature Thf is higher than the temperature threshold value Th2 and the integrated value σJb of the heat energy is greater than the integrated value threshold value Th3 (N in S20), the process proceeds to S24. If the intervention condition has not been changed in S24 (N in S24), the brake control device 26 ends the process.

[0079] Note that, when the brake device 24 changes from a low-temperature state to a non-low-temperature state while the intervention condition is satisfied, the change unit 36 may restore the changed condition out of the intervention condition and the intervention end condition once the intervention end condition is satisfied. In other words, when the brake device 24 changes from a low-temperature state to a non-low-temperature state while the intervention condition is satisfied, the change unit 36 does not need to restore the changed condition out of the intervention condition and the intervention end condition until the intervention end condition is satisfied. In this case, the condition can be restored after the intervention of the braking control is terminated. This makes it less likely that the occupant will feel uncomfortable.

[0080] Fig. 6 is a flowchart showing another process for changing the intervention condition of the brake control device 26 of Fig. 2. The process of Fig. 6 is executed repeatedly. The processes from S10 to S24 are the same as the processes from S10 to S24 of Fig. 5.

[0081] If the intervention condition has been changed in S24 (Y in S24), the change unit 36 determines whether braking control is currently being intervened (S28). If intervention is currently being performed (Y in S28), the change unit 36 returns to the processing of S28. If intervention is not currently being performed (N in S28), the change unit 36 restores the intervention condition (S26), and the braking control device 26 ends the processing.

[0082] The present invention has been described above based on the embodiments. However, the embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of each component and each treatment process, and that such modifications are also within the scope of the present invention. [Explanation of symbols]

[0083] 1...vehicle, 2...wheel, 3...disc brake unit, 10...vehicle control system, 22...brake fluid temperature sensor, 24...braking device, 26...braking control device, 28...brake actuator, 30...derivation section, 32...intervention determination section, 34...control section, 36...change section, 38...timer section, 40...accumulation section.

Claims

1. a control unit that controls the yaw moment and the roll moment by independently controlling the braking force applied to each wheel of the vehicle by the braking device from when an intervention condition is satisfied until an intervention termination condition is satisfied when the vehicle is turning; a change unit that, when the braking device is in a low temperature state, executes at least one of changing the intervention condition to be more likely to be satisfied and changing the intervention termination condition to be less likely to be satisfied compared to when the braking device is not in a low temperature state; A braking control device comprising:

2. the change unit returns the changed conditions of the intervention condition and the intervention termination condition to their original conditions when the temperature of the braking device changes from a low temperature state to a non-low temperature state.

2. The braking control device according to claim 1.

3. when the braking device changes from a low temperature state to a non-low temperature state, and the intervention termination condition is satisfied, the change unit restores the intervention condition and the changed one of the intervention termination condition to their original state.

2. The braking control device according to claim 1.

4. the intervention condition includes a steering angular velocity being equal to or greater than a first angular velocity threshold value, changing the intervention condition to be more likely to be satisfied includes changing the first angular velocity threshold to be smaller, the intervention termination condition includes that the steering angular velocity is less than a second angular velocity threshold value that is less than the first angular velocity threshold value, or that the elapsed time since the intervention condition was satisfied reaches an end time; changing the intervention termination condition to make it less likely to be satisfied includes at least one of changing the second angular velocity threshold to a smaller value and changing the termination time to a longer value.

3. The braking control device according to claim 1 or 2.

5. the change unit determines whether the braking device is in a low temperature state based on the elapsed time since the vehicle became drivable, the temperature of the brake fluid of the braking device, and an integrated value of heat generation energy in the brake pads of the braking device since the vehicle became drivable.

3. The braking control device according to claim 1 or 2.

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