JP7126907B2 - brake device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a brake system, and more particularly to control of an electric brake system or hydraulic brake system for a vehicle.

The following proposals have been made as a control method for the braking device.
1. A hydraulic brake that adjusts clearance (Patent Document 1).
2. An electric brake that varies the motor angular velocity in a state where there is a pad clearance according to the vehicle speed (Patent Document 2).
3. Electric brake with adjustable clearance (Patent Document 3).

JP 2010-215188 A JP-A-2002-67906 JP-A-6-327190

In the brake devices described in Patent Documents 1 to 3, when a brake force command is generally given by a driver's brake pedal operation, the brake device is often required to generate the brake force as quickly as possible. .
In order to generate braking force quickly, it is preferable to position the friction material as close as possible to the disc rotor. However, if the friction material is brought close to the disc rotor, the braking force will be small even though the friction material is not pressurized due to the influence of unevenness of the surface shape of the friction material or tilting of the caliper in the disc brake. So-called drag torque may be a problem.

SUMMARY OF THE INVENTION An object of the present invention is to provide a brake device that can improve the responsiveness of brake operation and prevent the drag torque from continuing to occur.

The brake device of the present invention comprises a brake rotor 8 that rotates integrally with the wheel, a friction material 9 that comes into contact with the brake rotor 8 to generate a braking force, a friction material operating means 17 that operates the friction material 9, A braking force command means 19a for generating a braking force target value, and a control device for controlling the friction material operating means 17 so that the braking force follows the braking force target value and using the vehicle acceleration force target value for control. 2, a braking device for a vehicle,
The control device 2 is
Either when the brake force target value is less than a threshold value or when a predetermined brake release request is recognized is determined as a brake release request state, and in this brake release request state, the friction material 9 and the brake rotor a first clearance control unit 30 for controlling the friction material manipulating means 17 according to a first clearance condition in which a clearance determined between 8 and 8 is generated;
Satisfying a condition that the vehicle acceleration force target value transitions from a state exceeding a threshold value to a state below a threshold value, or a change amount of the vehicle acceleration force target value changing in a direction that reduces the acceleration force of the vehicle. When the condition of changing by more than the amount is satisfied, or when both conditions are satisfied, it is determined that the acceleration stop operation has been performed, and when the brake release request state continues, the first clearance condition a second clearance control unit 31 that controls the friction material operating means 17 according to a second clearance condition that can reduce the clearance more than
After the state of the second clearance condition has elapsed while the brake release request state continues, the control device 2 operates according to a condition that allows the clearance to be expanded beyond the second clearance condition. The friction material operating means 17 is controlled.
The threshold, the defined clearance, and the defined amount of change are thresholds, clearances, and amounts of change that are arbitrarily determined by design or the like. , clearance, and amount of change.

According to this configuration, the first clearance control section 30 sets the clearance between the friction material 9 and the brake rotor 8 to a predetermined value when it determines that the brake release is required. The defined clearance is set, for example, so that the drag torque does not become a problem, but the large clearance may slow down the brake response.
When the acceleration stop operation is performed and the brake release request state continues, the clearance is reduced by the second clearance control section 31 . As a result, the braking response is quickened when the brake is operated, but as a trade-off, there is a concern that the fuel consumption or the electricity consumption will deteriorate due to the increase in the drag torque. Therefore, the drag torque can be prevented from being continuously generated by reducing the clearance at the initial stage of releasing the accelerator when the brake is likely to be operated and increasing the clearance as time elapses. Therefore, it is possible to improve the responsiveness of the brake operation and prevent the drag torque from being continuously generated.

Further, when the accelerator is released, deceleration simulating engine braking is often generated even in electrically driven vehicles such as EVs, HEVs, and FCVs. Therefore, even if a drag torque is generated due to the reduction of the clearance, it is a minute deceleration force generated in a situation where the driver of the vehicle feels the change in deceleration, so that the driver's sense of discomfort can be suppressed. can be done.

When expanding the clearance from the second clearance condition, the control device 2 controls the friction material so that the clearance condition changes continuously over time until reaching the first clearance condition. The operating means 17 may be controlled.
The term "continuous" also includes fine discrete step changes.
According to this configuration, by gradually changing the clearance condition with the lapse of time, it is possible to further suppress the discomfort of the operator.

The control device 2 controls that the clearance expansion time from the second clearance condition to the first clearance condition is longer than the clearance reduction time from the first clearance condition to the second clearance condition. Clearance conditions may be transitioned over a longer period of time.

According to this configuration, the process of reducing the clearance is performed within a relatively short period of time after the accelerator is turned off. Also, if the process of reducing the clearance is performed in a relatively short period of time, the effect of shortening the response time when the brake is operated is improved, so it is preferable to perform the clearance reduction in a relatively short period of time.
Since the process of increasing the clearance is performed in a state in which the operator does not perform any operation, the operator may feel uncomfortable if the clearance is increased in a short period of time. Also, if the process of expanding the clearance takes a relatively long time, the time for the drag torque to increase will be long, but since the ratio to the total running time of the vehicle is extremely small, it is necessary to take a relatively long time to expand the clearance. It is preferable to do so.

The control device 2 has a storage unit 33 that stores the reduction rate of the vehicle acceleration force target value immediately before it is determined that the acceleration stop operation has been performed,
The control device 2 determines the clearance reduction time from the first clearance condition to the second clearance condition based on the reduction rate of the vehicle acceleration force target value when the acceleration stop operation is performed. When the rate of decrease of the target vehicle acceleration force value is greater than a predetermined rate of decrease, the control device 2 shortens the clearance reduction time, and reduces the rate of decrease of the target vehicle acceleration force value. The clearance reduction time may be extended when the clearance reduction rate is smaller than the reduction rate.
The reduction rate of the vehicle acceleration force target value is the rate of change per unit time at which the vehicle acceleration force target value decreases over time.
The predetermined rate of decrease is a rate of decrease that is arbitrarily determined by design or the like, and is determined, for example, by obtaining an appropriate rate of decrease through either one or both of tests and simulations.

According to this configuration, when the accelerator is suddenly released, there is a high possibility that a sudden braking operation will be performed next. hard to feel as Therefore, when the accelerator is suddenly released, the clearance is reduced relatively quickly, that is, by shortening the clearance reduction time, the response speed to the next brake operation can be further improved.
Conversely, when the accelerator is gently released, it is considered unlikely that a sudden braking operation will be performed next, and furthermore, the change in deceleration is small, and the change in drag torque tends to feel uncomfortable. Therefore, when the accelerator is gently released, the discomfort of the operator can be reduced by reducing the clearance relatively slowly, that is, by extending the clearance reduction time.

The control device 2 has a storage unit 33 that stores the reduction rate of the vehicle acceleration force target value immediately before it is determined that the acceleration stop operation has been performed,
The control device 2 determines the clearance reduction amount by changing from the first clearance condition to the second clearance condition based on the reduction rate of the vehicle acceleration force target value when the acceleration stop operation is performed. The second clearance condition is set to a variable value so that the second clearance condition is a variable value, and the control device 2 reduces the clearance reduction amount when the reduction rate of the vehicle acceleration force target value is greater than a predetermined reduction rate may be increased, and a second clearance condition may be set to reduce the clearance reduction amount when the reduction rate of the vehicle acceleration force target value is smaller than a predetermined reduction rate.
The predetermined rate of decrease is a rate of decrease that is arbitrarily determined by design or the like, and is determined, for example, by obtaining an appropriate rate of decrease through either one or both of tests and simulations.

According to this configuration, when the accelerator is suddenly released, it is highly likely that a sudden braking operation will be performed next, and furthermore, the change in deceleration is large, and the generation of drag torque is less likely to feel uncomfortable. Therefore, when the accelerator is suddenly released, the response speed to the next brake operation can be further improved by setting the clearance reduction amount to be relatively large.
Conversely, when the accelerator is gently released, it is considered unlikely that a sudden braking operation will be performed next, and furthermore, the change in deceleration is small and the generation of drag torque is likely to feel uncomfortable. Therefore, when the accelerator is gently released, the driver's sense of discomfort can be further reduced by setting the clearance reduction amount to a relatively small amount.

The vehicle has a vehicle speed estimating means 40 for estimating a vehicle speed, and the control device 2 controls the clearance reduction time from the first clearance condition to the second clearance condition, and the second clearance condition. to the first clearance condition, and one or both of the clearance transition times are set to variable values based on the estimated vehicle speed, and the control device 2 sets the estimated vehicle speed to The clearance transition time may be shortened when the estimated vehicle speed is high, and the clearance transition time may be extended when the estimated vehicle speed is low.
When the vehicle speed is high, the vehicle speed is equal to or higher than a predetermined vehicle speed, and when the vehicle speed is low, the vehicle speed is equal to or lower than a threshold value. The determined vehicle speed and the threshold are determined by finding an appropriate vehicle speed and threshold through either or both of tests and simulations.

According to this configuration, when the vehicle speed is high, the effect of shortening the braking distance due to the improvement of the brake response speed is relatively high, and the actuator operation noise when changing the clearance is less noticeable. Therefore, by shortening the clearance reduction time at high speed, it is possible to further improve the response speed to the next brake operation.
When the vehicle speed is high, the loss due to the increase in drag torque is relatively large. Therefore, by shortening the clearance expansion time at high speeds, it is possible to shorten the drag torque increase time and improve fuel consumption or electricity consumption.

The vehicle has a vehicle speed estimating means 40 for estimating a vehicle speed, and the control device 2 calculates the estimated vehicle speed with respect to the amount of clearance reduction caused by changing from the first clearance condition to the second clearance condition. Either one or both of the first and second clearance conditions are set to variable values so as to have variable values based on, and the control device 2 reduces the clearance when the estimated vehicle speed is high may be increased, and the clearance reduction amount may be decreased when the estimated vehicle speed is low.

According to this configuration, when the vehicle speed is high, the effect of shortening the braking distance due to the improvement of the brake response speed is relatively high, and the actuator operation noise when changing the clearance is less noticeable. Therefore, the braking distance can be shortened by increasing the amount of clearance reduction at high speeds.

The friction material operating means 17 has an electric motor 4 and a mechanism for mechanically connecting the electric motor 4 and the friction material 9. The control device 2 is a device for controlling the electric motor 4. The function of controlling the friction material manipulating means 17 in the control device 2 may be a function of controlling the rotation angle or angle equivalent amount of the electric motor 4 .
When the mechanically connected mechanism is a linear motion mechanism 6 that converts the rotary motion of the electric motor 4 into a linear motion, the angle equivalent is a linear motion position converted into an equivalent lead, or a linear motion position sensor. It is a linear motion position or the like detected by this position sensor provided in the mechanism 6 .

The brake device of the present invention comprises a brake rotor that rotates integrally with a wheel, a friction material that comes into contact with the brake rotor to generate a braking force, a friction material operating means for operating the friction material, and a brake force target value. and a controller for controlling the friction material operating means so that the braking force follows the braking force target value and using the vehicle acceleration force target value for control. In the brake device, the control device determines a brake release request state when the brake force target value is less than a threshold value or when a predetermined brake release request is recognized, and outputs the brake release request. a first clearance control unit for controlling the friction material operating means according to a first clearance condition in which a predetermined clearance is generated between the friction material and the brake rotor in the state; and the vehicle acceleration force. Satisfy the condition that the target value transitions from above the threshold to below the threshold, or the amount of change in the vehicle acceleration force target value changes by a predetermined amount or more in the direction of decreasing the acceleration force of the vehicle. or when both conditions are satisfied, it is determined that an acceleration stop operation has been performed, and when the brake release request state continues, the clearance is set higher than the first clearance condition. and a second clearance control unit that controls the friction material operating means according to a second clearance condition that can reduce the second clearance condition while the brake release request state continues. After a predetermined period of time has passed in the state of (1), the friction material manipulating means is controlled according to a condition that allows the clearance to be larger than the second clearance condition. Therefore, it is possible to improve the responsiveness of the brake operation and prevent the drag torque from being continuously generated.

It is a figure which shows roughly the example which applied the electric brake device as the brake device which concerns on embodiment of this invention. It is a block diagram of a control system of the brake device. 3 is a block diagram showing a configuration example of a braking force controller in FIG. 2; FIG. It is a block diagram which shows another structural example of the same brake force controller. It is a flowchart which shows an example of the operation|movement flow of the clearance control part of the same brake device. 6 is a diagram showing an example of state transition in executing the operation flow of FIG. 5; FIG. FIG. 5 is a diagram showing an example of the relationship between vehicle speed and clearance transition time; FIG. 5 is a diagram showing another example of the relationship between vehicle speed and clearance transition time; It is a figure which shows an example of the relationship between a vehicle speed and a clearance. FIG. 5 is a diagram showing another example of the relationship between vehicle speed and clearance; FIG. 9 is a diagram showing still another example of the relationship between vehicle speed and clearance; FIG. 5 is a diagram showing an example of the relationship between the rate of decrease in vehicle acceleration force target value and clearance transition time; FIG. 5 is a diagram showing an example of the relationship between the rate of decrease of the vehicle acceleration force target value and the clearance; It is a figure which shows the operation example of the same brake device. It is a figure which shows the other operation example of the same brake device. It is a figure which shows the other example of operation|movement of the same brake device. It is a figure which shows the operation example of the brake device of a conventional structure. FIG. 5 is a block diagram of a control system using a hydraulic brake device as a brake device according to another embodiment of the present invention;

[First embodiment]
Embodiments of the present invention will be described with reference to FIGS. 1 to 16. FIG.
FIG. 1 is a diagram schematically showing an example in which an electric braking device is applied as a braking device according to an embodiment. The electric brake device 1 is mounted on a vehicle. The electric brake device 1 includes an electric actuator DA and a friction brake BR.

<Electric actuator DA and friction brake BR>
As shown in FIGS. 1 and 2, the electric actuator DA includes a linear actuator main body AH, a power supply device 3, and a control device 2, which will be described later. The direct-acting actuator main body AH has a friction material operating means 17 for operating a friction material 9, which will be described later, a parking brake mechanism 7, an angle sensor Sa, and a load sensor Sb. The friction material operating means 17 has an electric motor 4 , a linear motion mechanism 6 and a speed reducer 5 .

As shown in FIG. 1, the electric motor 4 is, for example, a permanent magnet synchronous motor. If a permanent magnet synchronous motor is applied as the electric motor 4, it is preferable because it is space-saving and has high efficiency and high torque. As the electric motor 4, for example, a DC motor using brushes, a reluctance motor not using permanent magnets, an induction motor, or the like can be applied.

A friction brake BR is provided for each wheel of the vehicle. The friction brake BR has a brake rotor 8 that rotates integrally with the wheel, and a friction member 9 that contacts the brake rotor 8 to generate a braking force. The friction material 9 is operated by an electric actuator DA. A mechanism can be used in which the friction material 9 is pressed against the brake rotor 8 by operating the linear motion actuator main body AH to generate a braking force by the frictional force. As the friction brake BR in this example, a disc brake device using a brake rotor 8, which is a brake disc, and a caliper (not shown) is applied, but a drum brake device using a drum and lining may be used.

The speed reducer 5 is a mechanism that reduces the speed of rotation of the electric motor 4, and includes a primary gear 12, an intermediate gear 13, and a tertiary gear 11, which are transmission parts. In this example, the speed reducer 5 reduces the rotation of the primary gear 12 attached to the rotor shaft 4a of the electric motor 4 by the intermediate gear 13 and transmits it to the tertiary gear 11 fixed to the end of the rotating shaft 10. Possible parallel gears are used. The transmission part has a play in which a contact state and a separation state are generated by switching between forward and reverse operations.

The linear motion mechanism 6 is a mechanism that converts the rotational motion output by the speed reducer 5 into linear motion of the linear motion portion 14 by means of a feed screw mechanism, and causes the friction material 9 to contact and separate from the brake rotor 8 . In other words, the linear motion mechanism 6 is a mechanism that mechanically connects the electric motor 4 and the friction material 9 . The direct-acting portion 14 is detented and supported so as to be movable in the axial direction indicated by arrow A1. A friction material 9 is provided at the outboard side end of the direct acting portion 14 . By transmitting the rotation of the electric motor 4 to the linear motion mechanism 6 via the speed reducer 5, the rotary motion is converted into linear motion, which is converted into the pressing force of the friction material 9, thereby generating braking force. . When the electric brake device 1 is mounted on the vehicle, the outer side of the vehicle in the vehicle width direction is called the outboard side, and the center side of the vehicle in the vehicle width direction is called the inboard side.

A linear solenoid, for example, is applied as the actuator 16 of the parking brake mechanism 7 . The locking member 15 is advanced by the actuator 16 and engaged by being fitted into a locking hole (not shown) formed in the intermediate gear 13, and by prohibiting the rotation of the intermediate gear 13, the parking lock state is established. to By removing the locking member 15 from the locking hole, the rotation of the intermediate gear 13 is permitted, and the unlocked state is established.

As shown in FIG. 2, the angle sensor Sa detects the rotation angle of the electric motor 4 (motor angle). For the angle sensor Sa, for example, a resolver, a magnetic encoder, or the like is preferably used because of its high accuracy and high reliability, but various sensors such as an optical encoder can also be used. Instead of using the angle sensor Sa, angle sensorless estimation may be used in which the motor angle is estimated from the relationship between the voltage and the current of the electric motor 4 in the control device 2, which will be described later.

The load sensor Sb detects the axial load of the linear motion mechanism 6 . As the load sensor Sb, for example, a magnetic sensor, a strain sensor, a pressure sensor, or the like that detects displacement or deformation of a predetermined member on which the load of the linear motion mechanism 6 acts can be used. Without using the load sensor Sb, the control device 2 may perform load sensorless estimation from, for example, the motor angle and the stiffness of the electric brake device, or the motor current and the efficiency of the linear actuator main body AH. In addition, various sensors such as a thermistor may be provided separately according to requirements.

The wheels can be provided with wheel speed sensors Sc for detecting wheel speed. As the wheel speed sensor Sc, for example, a magnetic pole sensor that detects the magnetic pole of a magnetic encoder that rotates integrally with the wheel, or a coil that detects inductance fluctuations of a rotor provided with unevenness can be used. Alternatively, instead of the wheel speed sensor Sc, another type of rotation sensor such as an angle sensor for detecting the rotational position of the wheel may be used. The wheel speed sensor Sc and the like may be used, for example, for antiskid control by the antiskid controller 18 for preventing locking of the wheels, in addition to the embodiment of the present invention.

<Configuration of control device 2>
FIG. 2 is a block diagram of the control system of the electric brake device 1. As shown in FIG. For example, a controller 2 and a direct-acting actuator main body AH are provided for each wheel. Each control device 2 controls a corresponding electric motor 4 . Each control device 2 is connected to a DC power supply device 3 and a host ECU 19 which is a host control means of each control device 2 . The power supply device 3 supplies electric power to the electric motor 4 and the control device 2 . For the power supply device 3, for example, a low-voltage (for example, 12V) battery of a vehicle in which the electric brake device 1 is mounted can be applied.

As the host ECU 19, for example, a vehicle control unit (VCU) that controls the entire vehicle is applied. The host ECU 19 has an integrated control function for each control device 2 . The host ECU 19 includes braking force command means 19a and acceleration force command means 19b. The brake command means 19a gives each controller 2 a command value (brake force target value), which is a sensor output that changes according to the amount of operation of a brake operation means (not shown). The acceleration force command means 19b provides each control device 2 with a sensor output (accelerator signal, etc.) that changes according to the amount of operation of an accelerator pedal or the like, as a vehicle acceleration force target value.

The brake force command means 19a may be the brake operation means itself, or may automatically issue a command without depending on the operation of the brake operation means, based on information such as the state of the vehicle and various sensors such as an automatic driving vehicle. It is also possible to obtain and output the value. The acceleration force command means 19b may be provided in an accelerator operation means such as an accelerator pedal, or, for example, as in an automatic driving vehicle, based on information such as the vehicle state and various sensors, the operation of the accelerator operation means may be controlled. It is also possible to automatically obtain and output a command value without relying on it.

Each control device 2 includes various control calculators that perform control calculations, a motor driver 20, and sensors. The various control calculators are configured by, for example, processors such as microcomputers, calculators such as FPGAs and ASICs, and peripheral circuits. The various control calculators include a motion state estimator 21, a current estimator 22, a brake force estimator 23, a wheel speed estimator 24, a brake force controller 25, a current controller 26 and an antiskid controller 18.

The motion state estimator 21 estimates the rotational motion state of the electric motor 4 from the output of the angle sensor Sa. The motion state estimator 21 may have a function of estimating the state quantity of the motor rotational motion such as the electric motor angle (estimated motor angle) and angular velocity used for control calculation from the output of the angle sensor Sa, for example. . The motion state estimator 21 may have, for example, a function of estimating a further predetermined calculus value such as the angular acceleration of the electric motor 4, or a disturbance observer function of estimating a disturbance. determined as appropriate.

The electric motor angle may be, for example, an electrical angle phase used for current control, or a total rotation angle corrected for overlap and underlap of the angle sensor Sa used for angle control. The angular velocity of the electric motor 4 may be a mechanical angular velocity or an electrical angular velocity, or may be a physical quantity based on a linear coordinate system such as a position or velocity estimated based on the equivalent lead of the linear motion mechanism 6. Well, units, coordinate systems, etc. should be handled appropriately based on control requirements. The physical quantities may be estimated using, for example, a configuration such as a state estimation observer, or may be a direct calculation such as back calculation based on calculus or inertia equations.

The current estimator 22 has a function of estimating the current used for control calculation from the output of the current sensor Sd. The current sensor Sd can be, for example, a sensor consisting of an amplifier that detects the voltage across the shunt resistor, or a non-contact sensor that detects the magnetic flux around the conduction path of the phase current of the electric motor 4, or the like. The current estimator 22 may, for example, be configured to detect terminal voltages of elements that constitute the motor driver 20 . As another configuration, the current estimator 22 may be configured to estimate the primary current by a single current sensor provided on the low side or the high side, and obtain the motor phase current based on the motor characteristics or the like. Alternatively, feedforward control can be performed based on the motor characteristics such as the inductance or resistance of the electric motor 4 without providing any current sensor.

The current controller 26 has a function of tracking the motor current to a predetermined target value. In the current controller 26, the motor current to be controlled is, for example, axis current control on the d-axis and the q-axis that are converted to orthogonal axes synchronized with the rotor magnetic poles. However, for example, a method of directly controlling an actual current value such as a three-phase alternating current may be used. For example, if the electric motor 4 is a DC motor with brushes, the current controller 26 can directly control the direct current. In FIG. 2, an example of feedback control of the estimated current is shown, but as described above, feedforward control based on the motor characteristics may be used, or feedback and feedforward such as non-interfering control may be used in combination as appropriate. It is good also as control to carry out.

The braking force estimator 23 has a function of estimating braking force (estimated braking force) from the output of the load sensor Sb. Alternatively, as described above, the load estimator 23 may have an angle sensorless estimation function or a load sensorless estimation function without using the load sensor Sb. As another configuration, the braking force estimator 23 may have, for example, a configuration in which a braking torque sensor is provided on each wheel and the braking force is estimated from the output of this braking torque sensor.

The braking force controller 25 includes a braking force control section 27 , a clearance control section 28 and a brake release determination section 29 .
The braking force control unit 27 performs control calculations for generating a predetermined braking force. The brake force control unit 27 performs feedback control calculation so that the estimated brake force follows the brake force target value by the brake force command means 19a. The physical quantity used in the calculation in the braking force control unit 27 is appropriately selected depending on the convenience of design, such as the actuator position calculated from the motor angle and the equivalent lead of the linear motion mechanism, or the motor torque obtained from the motor current. shall be In addition, the braking force control unit 27 can use feedforward control or the like, or can use feedforward control in addition to feedback control as appropriate.

The clearance control unit 28 performs control calculations for releasing the brake. A clearance control unit 28 receives a motor angle target value from the motion state estimator 21 for providing a predetermined clearance between the friction material 9 of the friction brake BR and the brake rotor 8 when the brake is released. It has a function of performing control calculations so that the estimated motor angle follows. For example, if the above function is a function of estimating the axial position of the linear motion part 14 (FIG. 1) of the linear motion actuator main body AH from the motor angle and the equivalent lead of the linear motion mechanism 6, it is preferable because the cost is reduced. However, it is also possible to separately provide a position sensor (not shown) for detecting the axial position of the linear motion part 14 (FIG. 1) in the linear motion actuator main body AH and control the estimated position using the position sensor.

The clearance control section 28 includes a first clearance control section 30 , a second clearance control section 31 and a clearance reduction determination section 32 . The first clearance control section 30 provides a defined clearance between the friction material 9 and the brake rotor 8 . The second clearance control section 31 reduces the clearance more than the first clearance control section 30 does. The clearance reduction determination unit 32 acquires the vehicle acceleration force target value of the acceleration force command means 19b for accelerating the vehicle by the vehicle driving force of the electric motor 4 or the like. When the acquired vehicle acceleration force target value reaches a target value equivalent to stopping the acceleration of the vehicle (=releasing the accelerator pedal), the clearance reduction determination unit 32 shifts the first clearance control unit 30 to the second clearance control. A switching signal for switching is output to the unit 31 .

Here, the first and second clearance control sections 30 and 31 are shown to have at least two or more clearance control sections having the above relationship. That is, for example, according to the running conditions of the vehicle or the state of wear of the friction brake BR, a plurality of the first and second clearance control units 30 and 31 are provided, and these are switched selectively or continuously. good too.

The brake release determination unit 29 determines whether to release the brake. Specifically, the brake release determination unit 29 has a function of determining to release the brake (brake release request state) when the brake force target value is less than a predetermined threshold value. Alternatively, the brake release determination unit 29 may also have a function of determining that the brake release request state exists when the amount of change in the brake force target value has changed by a greater than a predetermined amount in the direction of decreasing the brake force.

The braking force controller 25 outputs to the current controller 26 a motor current target value for finally driving the desired motor. The current controller 26, for example, has a function of converting the motor current target value into a current value that generates a desired torque based on predetermined motor characteristics. For the above conversion, for example, if an LUT or the like of the current value corresponding to the motor angular velocity and torque is provided in the storage unit 33, the calculation load is preferably small. It can also be obtained by a predetermined arithmetic expression, such as a calculation expression, or a calculation expression for obtaining a current condition for a desired torque from a motor phase resistance or phase inductance using a convergence arithmetic expression such as the Newton-Raphson method.

The current command value obtained by the current controller 26 may be, for example, a quadrature axis current (d-axis current, q-axis current) with respect to a predetermined electrical angle phase, or an alternating current having a predetermined phase and frequency. good too. Alternatively, it may be a current command value considering the slip angle of an induction motor, or a DC current command for a DC motor with a brush.

The current controller 26 may not be provided, and the braking force controller 25 may include the function of the current controller 26 described above. 2 generates a command value for the current controller 26, and the current controller 26 generates a motor drive voltage signal (such as PWM). Instead, the braking force controller 25 performs calculations in such a manner that the motor current control system corresponding to the current controller 26 in FIG. It may be configured to output.

The motor driver 20 converts the DC power of the power supply device 3 into AC power used to drive the electric motor 4 based on the current command value given from the current controller 26 . If the motor driver 20 constitutes a half-bridge circuit including switch elements such as FETs and performs PWM control that determines the voltage applied to the motor according to a predetermined duty ratio, it is inexpensive and has high performance. Alternatively, a transformer circuit or the like (not shown) may be provided to perform PAM control.

<Configuration Example of Braking Force Controller 25>
FIG. 3 is a block diagram showing a configuration example of the braking force controller 25 of FIG.
The first clearance control section 30 has a first clearance target setting section 34 , a switching section 35 and a motor angle control section 36 . The second clearance control section 31 has a second clearance target setting section 37 , the switching section 35 and the motor angle control section 36 .
The clearance reduction determination unit 32 determines whether or not to reduce the clearance based on a vehicle acceleration target value such as an accelerator signal, for example, and switches the values set by the first and second clearance target setting units 34 and 37 . The switching unit 35 to which the switching signal is supplied from the clearance reduction determining unit 32 and the switching signal may be, for example, binary switching or continuous switching.

At this time, continuous switching includes discrete values obtained by subdividing the intermediate value. With respect to the second clearance target p2 output from the second clearance target setting unit 37, the clearance target p is set as p=α·p1+(1−α)·p2 where a coupling function such as 0≦α≦1 It may be derived based on, it may be smoothed through a predetermined low-pass filter (Low-pass filter, abbreviation: LPF) etc. after performing the above-mentioned binary switching, or it may be subdivided , pn may be set in advance to perform fine switching. Further, when the coupling function and the coupling coefficient α are used, α may be a coefficient that varies linearly with time, for example, a coefficient that varies nonlinearly such as a sine-like or an inverse function (fractional function). good too.

The motor angle control unit 36 derives a motor operation amount for controlling the motor angle so as to achieve the clearance target p given from the switching unit 35 .
The braking force control unit 27 derives a motor operation amount for generating a desired braking force.
A brake release determination unit 29 determines whether or not to release the brake from the brake force target value. The motor operation amount is set to generate a desired braking force. The switching unit 38 for switching the motor operation amount and its switching signal may be, for example, binary switching or continuous switching. The braking force controller 25 outputs a motor current target value which is the finally determined motor operation amount. It is also possible to separately provide a function of changing the motor torque to a predetermined motor current by using the motor operation amount as the motor torque target value.

<Another configuration example of the braking force controller 25>
FIG. 4 is a block diagram showing another configuration example of the braking force controller 25. As shown in FIG. As a change from FIG. 3, a braking force angle converting section 39 is provided in the braking force control section 27 to obtain a motor angle target value for generating a desired braking force. The brake release determination unit 29 determines the motor angle target value by switching between the motor angle target value for achieving the clearance target p and the motor angle target value for generating the braking force. The motor angle control unit 36 performs a follow-up control calculation on this motor angle target value to derive a motor current target value, which is a motor operation amount. Compared to the configuration example of FIG. 3, the configuration example of FIG. 4 requires data or functions for converting the braking force into the motor angle, but is advantageous in that the control calculation unit can be integrated into one.

<Operation flow of clearance control unit>
FIG. 5 is a flow chart showing an example of the operation flow of the clearance control section. Note that FIG. 5 does not show a specific example of a program or the like at the time of implementation, but only shows the concept of the overall operation flow. shall be included as appropriate. The description will be made with appropriate reference to FIG. 2 or FIG. 3 or the like.

After starting this process, the brake release determination unit 29 determines whether or not to release the brake (step S1). The brake release determination unit 29 releases the brake based on, for example, a state in which the target braking force value is below a predetermined threshold value, or the target braking force value has decreased by a degree of change greater than or equal to a predetermined degree, or both. You can decide whether or not The brake force target value may be, for example, a brake force obtained from a brake operating means such as a brake pedal based on a predetermined conversion condition, or an output signal of the brake operating means such as the stroke of the brake pedal itself. may Alternatively, it may be a brake force target value transmitted from a host ECU 19 such as a vehicle integrated control unit (VCU).

When it is determined not to release the brake (step S1: no), the braking force control unit 27 derives the motor operation amount for generating the desired braking force (step S2), and ends this process. Upon determining to release the brake (step S1: yes), the clearance control unit 28 determines whether the vehicle acceleration force target value has decreased and transitioned to zero (step S3). The clearance control unit 28 makes a determination based on, for example, an accelerator off operation in a general automobile. The accelerator off operation includes both an accelerator off operation performed by the operator and an accelerator off operation automatically performed by the host ECU 19 in automatic driving or vehicle motion control.

The clearance control unit 28, for example, is based on a state in which the target vehicle acceleration force value is below a predetermined threshold value, or the target vehicle acceleration force value has decreased by a predetermined degree of change (amount of change) or more, or both. The above judgment may be made by Further, the vehicle acceleration force target value may be, for example, an acceleration force obtained from an accelerator operating means such as an accelerator pedal based on a predetermined conversion condition, or an output signal of an accelerator operating means such as a stroke of an accelerator pedal. It may be that. Alternatively, it may be a vehicle acceleration force target value transmitted from a host ECU 19 such as a vehicle integrated control unit (VCU).

When it is detected that the vehicle acceleration force target value has changed or is changing to zero (step S3: yes), the clearance control unit 28 sets the clearance to the second clearance target (second clearance condition) p2. (step S4), otherwise (step S3: no), the clearance is set to the first clearance target (first clearance condition) p1 (step S7). After step S7, the process proceeds to step S8. A first clearance target p1 indicates a constant clearance, and a second clearance target p2 indicates a reduced clearance with a relationship of p2<p1.

After setting the clearance to p2 in step S4, if a predetermined time has passed (step S5: yes), the clearance control unit 28 shifts the clearance to p1 (step S6). The predetermined time is appropriately determined based on the behavior of the vehicle and the driver's feeling. The trade-off is the worsening of fuel consumption/electricity consumption due to As an example, by setting the predetermined time to about 100 msec to several seconds, it is possible to improve the responsiveness of the brake to a brake operation with a relatively high degree of urgency and prevent deterioration of fuel/electricity consumption. The control device 2 controls the electric motor 4 so as to achieve the finally determined clearance amount (step S8). After that, this process is terminated.

FIG. 6 is a diagram showing an example of state transition in executing the operation flow of FIG. ST. 21 is the first clearance target p1 in FIG. 5, and ST. 23 corresponds to the second clearance target p2, and ST. 22 and ST. 24 correspond to the intermediate states transitioning to p1 and p2, respectively. Also ST. 23 to ST. 24 corresponds to "elapsed predetermined time" in step S5 in FIG.

ST. 22 and ST. When the predetermined times t1 and t2 of 24 are lengthened, the clearance changes gradually, and when they are shortened, the clearance changes sharply. In particular, if the required time is zero (states ST.22 and ST.24 are not passed through), the clearance changes as quickly as possible according to the operating speed and control band of the actuator. The predetermined times t1 and t2 may be adjusted, for example, by making the change of the control target value such as the motor angle steeper or slower. or both may be used in combination.

For example, ST. At 22, shortening the predetermined time t1 can be advantageous in terms of shortening the braking distance and brake feeling by shortening the response time to the next braking operation. Also ST. In 24, shortening the predetermined time t2 can be advantageous in terms of improving fuel/electricity consumption. As a contradiction, shortening of the predetermined times t1 and t2 may be disadvantageous in terms of discomfort to the operator.

For the trade-off between the predetermined times t1 and t2, for example, the predetermined time t1 may be relatively short and the predetermined time t2 may be relatively long. In other words, the controller 2 (FIG. 2) determines that the predetermined time (clearance expansion time) t2 from the second clearance condition to the first clearance condition is changed from the first clearance condition to the second clearance condition. The clearance condition may be changed so as to be longer than the predetermined time (clearance reduction time) t1.

At this time, the clearance shortening operation is performed in accordance with a change in vehicle behavior accompanying accelerator-off, such as engine braking (engine braking simulation in an electric vehicle). Discomfort can be suppressed relatively mildly. Moreover, ST. Since the clearance expansion of 24 is considered to be often executed without any operation to the vehicle, by setting the predetermined time t2 sufficiently long, it is possible to reduce the driver's sense of discomfort. For example, t1 may be adjusted from 10 msec to several hundred msec, and t2 may be adjusted from 1 sec to several tens of sec.

The controller 2 (FIG. 2) controls each state ST. 21, ST. 22, ST. 23, ST. 24 and the parameters of the transition conditions, variable parameters may be used according to the vehicle speed of the vehicle equipped with the electric brake device. At that time, a process of switching between two values with respect to a predetermined vehicle speed threshold may be performed, or a process of continuously (stepwise) changing depending on the vehicle speed may be performed, or these may be used in combination. The vehicle speed can be estimated by vehicle speed estimation means 40 (FIG. 2). When the parameter is changed continuously depending on the vehicle speed, the parameter may be changed linearly with respect to the vehicle speed, or may be changed non-linearly such as sinusoidally or inversely. Moreover, an upper limit value and a lower limit value may be set, and these may be used together.

<Transition of clearance, etc.>
FIG. 7 shows an example in which t1 is shortened and t2 is kept constant as the vehicle speed increases. Moreover, FIG. 8 shows an example in which both t1 and t2 are shortened when the vehicle speed becomes high.
The higher the vehicle speed, the greater the effect on the braking distance due to the brake response speed. Therefore, shortening t1 has the advantage of improving brake response, and the higher the vehicle speed, the greater the loss due to drag torque. Therefore, the effect of suppressing deterioration of fuel consumption/electricity consumption by changing t2 in a short time is increased. At this time, the shorter the clearance transition times t1 and t2, the worse the NVH (Noise, Vibration, and Harshness) due to the actuator operation noise. Since the background noise is increased due to the influence, the deterioration of the NVH is less likely to occur by setting the clearance transition time according to the vehicle speed.

In FIG. 9, the control device 2 (FIG. 2) increases the clearance reduction from the first clearance condition (ST.21) as the vehicle speed increases under the second clearance condition (ST.23) ( In other words, an example is shown in which the clearance p2 is made variable so that the clearance becomes smaller. The higher the vehicle speed, the greater the effect of the brake response speed on the braking distance. At this time, the larger the clearance reduction amount by changing from the first clearance condition (ST.21) to the second clearance condition, the larger the actuator needs to be operated, which may deteriorate NVH. However, the higher the vehicle speed, the greater the background noise due to the effects of road noise and wind noise.

FIG. 10 shows an example of the process of increasing the clearance under the first clearance condition (ST.21) when the vehicle speed becomes high. The first clearance condition is, in other words, a steady clearance state, and enlarging the clearance at high speeds can reduce drag torque and effectively improve fuel/electricity consumption. At this time, a delay in brake response may become a problem, but the above problem can be solved by the process of reducing the clearance under the second clearance condition.

That is, FIG. 10 shows a configuration in which the clearance is expanded during high-speed running to reduce the drag torque, while the amount of clearance reduction when the accelerator is released increases, thereby suppressing the decrease in responsiveness to brake operation after the accelerator is released. ing.
FIG. 11 shows an example in which the configurations of FIGS. 9 and 10 are combined and both p1 and p2 have variable values according to the vehicle speed.

Each state ST. 21, ST. 22, ST. 23, ST. 24, and the parameter of the transition condition, as shown in FIG. A variable parameter may be used according to the rate of decrease of the target value (=minus/differential value in the accelerator off direction).

At that time, the control device 2 may perform binary switching for the threshold value of the reduction rate of the vehicle acceleration force target value, and the parameter is changed continuously (stepwise) depending on the reduction rate of the vehicle acceleration force target value. target), or these may be used in combination. When the parameter is changed continuously depending on the rate of decrease, it may be changed linearly with respect to the rate of decrease, or may be changed non-linearly such as sinusoidally or inversely. Moreover, an upper limit value and a lower limit value may be set, and these may be used together.

FIG. 12 shows ST. 22 shows an example in which t1 is shortened when the degree of decrease (decrease rate) of the stored vehicle acceleration force target value is steep.
The shorter the clearance transition time, the more likely the driver will feel discomfort due to the sudden increase in drag torque. Since the behavior of the vehicle changes relatively greatly due to the occurrence of the accelerator off operation, the discomfort described above is less likely to occur. Furthermore, after abrupt accelerator-off operation, there is a relatively high possibility that a sudden brake operation will be performed. 22 in a short period of time has the advantage of improving brake response.

FIG. 13 shows that, under the second clearance condition (ST.23), when the degree of decrease in the stored vehicle acceleration force target value is steep, the clearance reduction amount from the first clearance condition (ST.21) is An example in which the clearance p2 is made variable so as to increase is shown.
If the clearance is reduced, the drag torque may increase, which may increase the driver's sense of discomfort. Since the behavior of the vehicle changes relatively largely due to the occurrence of the accelerator off operation, the uncomfortable feeling is less likely to occur. Furthermore, after a sharp accelerator-off operation, there is a relatively high possibility that a sudden brake operation will be performed, and the merit of improving the brake response by further reducing the clearance is increased.

<Example of operation of the electric brake device>
FIG. 14 shows the operation when the accelerator is turned off with the brake released. Even if the drag torque increases by reducing the clearance from p1 to p2, the effect on fuel/electricity consumption can be minimized because the clearance reduction state is limited.
FIG. 15 shows an example in which a relatively slow accelerator off operation is performed with respect to FIG. In the operation example of FIG. 15, the clearance reduction amount is smaller and the clearance transition time is longer than in FIG.

16 and 17 show an example in which the vehicle acceleration force target value becomes zero with the brake released, and then the brake is operated. FIG. 16 shows a case where the configuration of the electric brake device of this embodiment is applied, and FIG. 17 shows a case where the conventional configuration is applied. In the operation example of FIG. 16, the clearance is reduced from p1 to p2 in advance, so that the brake can respond more quickly than the conventional configuration of FIG.

<Effect>
When the first clearance control unit 30 determines that the brake release is required, the first clearance control unit 30 sets the clearance between the friction material 9 and the brake rotor 8 to a predetermined value. The defined clearance is set, for example, so that the drag torque does not become a problem, but the large clearance may slow down the brake response.
When the acceleration stop operation is performed and the brake release request state continues, the clearance is reduced by the second clearance control section 31 . As a result, the braking response is quickened when the brake is operated, but as a trade-off, there is a concern that the fuel consumption or the electricity consumption will deteriorate due to the increase in the drag torque. Therefore, the drag torque can be prevented from being continuously generated by reducing the clearance at the initial stage of releasing the accelerator when the brake is likely to be operated and increasing the clearance as time elapses. Therefore, it is possible to improve the responsiveness of the brake operation and prevent the drag torque from being continuously generated.

Further, when the accelerator is released, deceleration simulating engine braking is often generated even in electrically driven vehicles such as EVs, HEVs, and FCVs. Therefore, even if a drag torque is generated due to the reduction of the clearance, it is a minute deceleration force generated in a situation where the driver of the vehicle feels the change in deceleration, so that the driver's sense of discomfort can be suppressed. can be done.

<About other embodiments>
In the following description, the same reference numerals are given to the parts corresponding to the items previously described in each embodiment, and duplicate descriptions are omitted. When only a portion of the configuration is described, the other portions of the configuration are the same as those previously described unless otherwise specified. The same configuration has the same effect. It is possible not only to combine the parts specifically described in each embodiment, but also to partially combine the embodiments if there is no particular problem with the combination.

<Configuration example of hydraulic brake device>
FIG. 18 shows a configuration example of a hydraulic brake using hydraulic cylinders and hydraulic control valves instead of the electric brake device of FIG.
The brake force command means 19a and the master cylinder 41 may be, for example, a directly connected brake pedal and master cylinder, or may be an electric master cylinder controlled by an electric motor or the like and an electric control wire or the like. good.

The braking force estimator 23 may be configured, for example, by providing a hydraulic pressure sensor Se such as a hydraulic pressure sensor in the master cylinder 41 as shown in FIG. A configuration may be adopted in which a hydraulic pressure sensor is provided in the brake cylinder 42 to more directly estimate the braking force. In addition, without providing a hydraulic pressure sensor, for example, it is possible to perform hydraulic pressure sensorless estimation such as estimating the brake pressure that can be generated in advance from the stroke of the brake pedal. 2, the brake force controller 25 is configured as a controller that controls the hydraulic pressure of the brake cylinder 42 by means of an electromagnetic valve 43 provided in the hydraulic actuator AU. Alternatively, when an electric master cylinder is used as described above, the braking force controller 25 can also function as a controller for controlling the hydraulic pressure of the electric master cylinder.

2 to 4, FIG. 18, etc. merely show the concept of the functional configuration, and elements not shown are provided as appropriate according to requirements. Also, each functional block is provided for convenience, and can be integrated or divided as appropriate in terms of hardware or software for the convenience of implementation.
Each block diagram is for describing the flow of functional signals, and does not define the order of operations and timing for implementation. The order of calculation can be set arbitrarily as long as the function does not break down, and the timing is set as appropriate, such as by introducing multi-rate processing that is executed at multiple sampling rates so that calculation can be performed at high speed or low speed depending on the function. It shall be possible.
This embodiment is not intended to select any one example, and may have a configuration in which a part or the whole is merged if necessary, as long as there is no contradiction in terms of implementation.

The speed reducer 5 may be, for example, a speed reducer such as a worm gear or a planetary gear.
As the linear motion mechanism 6, various screw mechanisms such as a planetary roller screw and a ball screw, and various mechanisms for converting rotary motion into linear motion such as a ball ramp can be used.

As mentioned above, although the form for implementing this invention was demonstrated based on embodiment, embodiment disclosed this time is an illustration and is not restrictive at all points. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the meaning and range of equivalents of the scope of the claims.

DESCRIPTION OF SYMBOLS 2... Control apparatus 4... Electric motor 8... Brake rotor 9... Friction material 17... Friction material operation means 19a... Brake force command means 30... First clearance control part 31... Second clearance control Part 33... Storage part 40... Vehicle speed estimating means

Claims (7)

A brake rotor that rotates integrally with a wheel, a friction material that comes into contact with the brake rotor to generate a braking force, a friction material operating means that operates the friction material, and a braking force command means that generates a braking force target value. and a control device that controls the friction material operating means so that the braking force follows the braking force target value, and uses the vehicle acceleration force target value for control,
The control device is
A brake release request state is determined when the brake force target value is less than a threshold value or when a predetermined brake release request is recognized. a first clearance control section for controlling the friction material operating means according to a first clearance condition in which a clearance determined between
Satisfying a condition that the vehicle acceleration force target value transitions from a state exceeding a threshold value to a state below a threshold value, or a change amount of the vehicle acceleration force target value changing in a direction that reduces the acceleration force of the vehicle. When the condition of changing by more than the amount is satisfied, or when both conditions are satisfied, it is determined that the acceleration stop operation has been performed, and when the brake release request state continues, the first clearance condition a second clearance control unit that controls the friction material operating means according to a second clearance condition that can reduce the clearance more than
After a predetermined time has elapsed while the brake release request state continues and the state of the second clearance condition has passed, the control device controls the control device according to a condition that allows the clearance to be expanded beyond the second clearance condition. controlling the friction material operating means;
The clearance expansion time from the second clearance condition to the first clearance condition is longer than the clearance reduction time from the first clearance condition to the second clearance condition. A brake device that changes clearance . 2. The brake device according to claim 1, wherein when the control device increases the clearance from the second clearance condition, the control device continuously increases the clearance over time until reaching the first clearance condition. A braking device for controlling the friction material manipulating means such that the 3. The brake device according to claim 1 , wherein said control device stores a reduction rate of said vehicle acceleration force target value at the time when it is determined that said acceleration stop operation has been performed. has a part
The control device varies the clearance reduction time from the first clearance condition to the second clearance condition based on the reduction rate of the vehicle acceleration force target value when the acceleration stop operation is performed. and the control device shortens the clearance reduction time when the reduction rate of the target vehicle acceleration force value is greater than the predetermined reduction rate, and reduces the reduction rate of the target vehicle acceleration force value to the predetermined reduction rate. braking device for extending said clearance reduction time when less than a ratio. A brake rotor that rotates integrally with a wheel, a friction material that comes into contact with the brake rotor to generate a braking force, a friction material operating means that operates the friction material, and a braking force command means that generates a braking force target value. and a control device that controls the friction material operating means so that the braking force follows the braking force target value, and uses the vehicle acceleration force target value for control,
The control device is
A brake release request state is determined when the brake force target value is less than a threshold value or when a predetermined brake release request is recognized. a first clearance control section for controlling the friction material operating means according to a first clearance condition in which a clearance determined between
Satisfying a condition that the vehicle acceleration force target value transitions from a state exceeding a threshold value to a state below a threshold value, or a change amount of the vehicle acceleration force target value changing in a direction that reduces the acceleration force of the vehicle. When the condition of changing by more than the amount is satisfied, or when both conditions are satisfied, it is determined that the acceleration stop operation has been performed, and when the brake release request state continues, the first clearance condition a second clearance control unit that controls the friction material operating means according to a second clearance condition that can reduce the clearance more than
After a predetermined time has elapsed while the brake release request state continues and the state of the second clearance condition has passed, the control device controls the control device according to a condition that allows the clearance to be expanded beyond the second clearance condition. controlling the friction material operating means;
The control device has a storage unit that stores a reduction rate of the vehicle acceleration force target value at the point in time when it is determined that the acceleration stop operation has been performed,
The control device determines the amount of clearance reduction due to the transition from the first clearance condition to the second clearance condition based on the reduction rate of the vehicle acceleration force target value when the acceleration stop operation is performed. The second clearance condition is set to a variable value, and the control device increases the clearance reduction amount when the rate of decrease of the target vehicle acceleration force value is greater than a predetermined rate of decrease. and a second clearance condition for reducing the amount of clearance reduction when the reduction rate of the vehicle acceleration force target value is smaller than a predetermined reduction rate. A brake rotor that rotates integrally with a wheel, a friction material that comes into contact with the brake rotor to generate a braking force, a friction material operating means that operates the friction material, and a braking force command means that generates a braking force target value. and a control device that controls the friction material operating means so that the braking force follows the braking force target value, and uses the vehicle acceleration force target value for control,
The control device is
A brake release request state is determined when the brake force target value is less than a threshold value or when a predetermined brake release request is recognized. a first clearance control section for controlling the friction material operating means according to a first clearance condition in which a clearance determined between
Satisfying a condition that the vehicle acceleration force target value transitions from a state exceeding a threshold value to a state below a threshold value, or a change amount of the vehicle acceleration force target value changing in a direction that reduces the acceleration force of the vehicle. When the condition of changing by more than the amount is satisfied, or when both conditions are satisfied, it is determined that the acceleration stop operation has been performed, and when the brake release request state continues, the first clearance condition a second clearance control unit that controls the friction material operating means according to a second clearance condition that can reduce the clearance more than
After a predetermined time has elapsed while the brake release request state continues and the state of the second clearance condition has passed, the control device controls the control device according to a condition that allows the clearance to be expanded beyond the second clearance condition. controlling the friction material operating means;
The vehicle has vehicle speed estimating means for estimating a vehicle speed, and the control device controls a clearance reduction time from the first clearance condition to the second clearance condition, and from the second clearance condition to the Either one or both of the clearance expansion time until reaching the first clearance condition is set to a variable value based on the estimated vehicle speed, and the control device sets the estimated vehicle speed to a variable value. A brake device that shortens the clearance transition time when the vehicle speed is high and extends the clearance transition time when the estimated vehicle speed is low. 6. The brake system according to claim 1 , wherein the vehicle has vehicle speed estimating means for estimating a vehicle speed, and the control device calculates the second clearance condition from the first clearance condition. Either one or both of the first and second clearance conditions are set to variable values so that the amount of clearance reduction resulting from reaching the clearance conditions is a variable value based on the estimated vehicle speed, The control device increases the clearance reduction amount when the estimated vehicle speed is high, and decreases the clearance reduction amount when the estimated vehicle speed is low. 7. The brake device according to any one of claims 1 to 6 , wherein the friction material operating means has an electric motor and a mechanism for mechanically connecting the electric motor and the friction material, The control device is a device for controlling the electric motor, and the function of controlling the friction material operating means in the control device is a function of controlling a rotation angle or angle equivalent amount of the electric motor.

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