JP7089871B2 - Electric brake device - Google Patents

Description

The present invention relates to an electric brake device capable of improving vehicle feeling and reducing operating noise.

The following techniques have been proposed as electric motor devices and electric actuators using electric motors.
A technique of decelerating the rotational driving force of an electric motor by a speed reducer, converting it into linear motion via a linear motion mechanism, and pressing and contacting a friction pad with a disc rotor to add braking force (Patent Document 1).

Japanese Patent Application Laid-Open No. 2003-247576

For example, in an electric brake device as in Patent Document 1, when the operator of a vehicle equipped with this electric brake device requests the brake release such as releasing the brake pedal, the electric brake device has a friction material and a brake rotor. The electric motor is rotated in the direction of separation to release the brake. At this time, if the angular velocity of the electric motor is not sufficient, for example, the time lag from when the driver releases the brake pedal until the braking force is released and the vehicle starts running becomes large, resulting in deterioration of the vehicle feeling such as a brake drag feeling. It may be connected.

On the other hand, when the brake is released and the piston moves to a predetermined standby position or the like, the braking force is released and there is no load, so that the operating noise of the mechanical coupling portion is likely to occur. In particular, when the motor angular velocity is large, it is necessary to suddenly decelerate the motor angular velocity in order to position the motor at a motor angle that is a predetermined piston standby position, which may cause a loud operating noise and worsen NVH.

In other words, if the brake drag feeling is reduced and the vehicle feeling is improved, the NVH deteriorates due to the increase in the motor angular velocity, and if the motor angular velocity is limited to improve the NVH, the brake drag feeling is achieved. It becomes a trade-off problem that the vehicle feeling deteriorates.

An object of the present invention is to provide an electric brake device capable of improving the vehicle feeling and reducing the operating noise.

In the electric brake device of the present invention, the brake rotor 8, the friction material 9 that is in contact with the brake rotor 8 to generate a braking force, the electric motor 4, and the output of the electric motor 4 are pressed against the friction material 9. In an electric brake device including a friction material operating means 6 for converting to, and a control device 2 for controlling the electric motor 4 so that the braking force follows a given braking force command value.
The control device 2 is
When the brake force command value is zero or the brake release request for releasing the brake force is recognized, the motor angle command value is set so that a defined clearance is provided between the friction material 9 and the brake rotor 8. It has a brake release motor control unit that controls the angle of the electric motor 4 so as to follow it.
When the braking force is set to zero from the state in which the braking force is exerted, the brake release motor control unit overshoots the angle of the electric motor 4 with respect to the motor angle command value and then follows the motor angle command value. Has the function of
The defined clearance is a clearance arbitrarily determined by design or the like, and is determined by seeking an appropriate clearance by, for example, one or both of a test and a simulation.

According to this configuration, the motor control unit at the time of releasing the brake overshoots the angle of the electric motor 4 with respect to the motor angle command value when the braking force is set to zero from the state where the braking force is exerted. After that, when the brake is released, the motor control unit executes control to follow the motor angle according to the motor angle command value. In this way, by making the waveform that overshoots intentionally for the operation when releasing the brake, the braking force is quickly reduced to zero to reduce the brake drag feeling, and at the time of positioning to the brake standby position, it is sudden. By suppressing acceleration / deceleration, it is possible to reduce operating noise (improve NVH).

The brake release motor control unit uses the motor angle command value in which the specified clearance is provided as the first release command value, and the brake release motor control unit uses the first release command value. A second release command value having a predetermined overshoot characteristic may be calculated, and the electric motor 4 may be controlled to follow the second release command value.
The overshoot characteristic defined above is an overshoot characteristic arbitrarily determined by design or the like, and is determined by obtaining an appropriate overshoot characteristic by, for example, one or both of a test and a simulation.
In this case, since it is only necessary to calculate the second release command value having the overshoot characteristic defined for the first release command value, it is controlled as compared with the one that requires complicated processing such as controller initialization. The system can be simplified.

The control device 2 has an angular velocity estimation function unit 24 that estimates the current angular velocity of the electric motor 4.
The brake release motor control unit sets an angular acceleration limit value determined from the second release command value, and accelerates / decelerates the angular velocity estimated by the angular velocity estimation function unit 24 with the angular acceleration limit value. Has a function to calculate the angular velocity at the time of
The brake release motor control unit calculates the motor angle at the previous time when exercising at the calculated angular velocity, sets the calculated motor angle as the limit value of the motor angle command value, and sets this limit value as the first limit value. The value used for the waterfall as one release command value may be used as the second release command value.
The predetermined angular acceleration limit value is an angular acceleration limit value arbitrarily determined by design or the like, and is determined by obtaining an appropriate angular acceleration limit value by, for example, one or both of a test and a simulation.

The second release command value may be a value via a second-order or higher low-pass filter 26 having overshoot and attenuation characteristics defined for the first release command value.
The overshoot and attenuation characteristics defined above are overshoot and attenuation characteristics arbitrarily determined by design and the like, and are determined by, for example, one or both of test and simulation to obtain appropriate overshoot and attenuation characteristics. Be done.

The control device 2 has a braking force control calculation function that feedback-controls the electric motor 4 so as to exert a predetermined braking force via a calculation parameter including a feedback gain set based on the first control system characteristic. With a part
The brake release motor control unit is set at a predetermined angle from the state in which the braking force is exerted to zero by the calculation parameter including the feedback gain set based on the second control system characteristic. It has a function to feedback control the electric motor 4.
The second control system characteristic of the brake release motor control unit may be set so that the overshoot amount is larger and the establishment time is longer than the first control system characteristic.
The specified braking force and the specified angle are the braking force and the angle arbitrarily determined by the design and the like, and the appropriate braking force and the angle are obtained by, for example, one or both of the test and the simulation. Is determined.
The established time is the time until the control amount completes the follow-up to the predetermined command value and becomes a steady state. For example, the electric brake device sets the brake force command value to zero or releases the brake force. It can be the time from when the request is recognized until the overshoot converges.
In this case, since the control system characteristics can be directly adjusted, the actuator operation can be surely adjusted so as to have a low operating noise. However, processing such as appropriate initialization is required when the controller is switched.

When the braking force is reduced to zero from the state in which the braking force is exerted, the motor control unit at the time of releasing the brake rotates the electric motor 4 in a direction in which the friction material 9 and the brake rotor 8 are separated from each other, and the braking force is increased. The electric motor 4 is decelerated at a predetermined angular acceleration from the state where becomes zero, and the angle of the electric motor 4 is set with respect to the motor angle command value from the state where the angular speed of the electric motor 4 becomes zero. It may have a function of following control.
The defined angular acceleration is an angular acceleration arbitrarily determined by design or the like, and is determined by obtaining an appropriate angular acceleration by, for example, one or both of a test and a simulation.
In this case, the process is simple and easy to understand, and has the advantage that, for example, the overshoot characteristics can be easily adjusted. However, the calculation time may increase because conditional branching and judgment are required to properly transition the processing state.

When the braking force is reduced to zero from the state in which the braking force is exerted, the motor control unit at the time of releasing the brake causes the angle of the electric motor 4 to follow the motor angle command value determined from the state in which the braking force becomes zero. It has a function of limiting the output of the electric motor 4 between the two, and the output of the electric motor 4 limited by this function is the maximum of the electric motor 4 other than executing the limitation of the output of the electric motor 4. It may be smaller than the output.
The determined motor angle command value is a motor angle command value arbitrarily determined by design or the like, and is determined by obtaining an appropriate motor angle command value by, for example, one or both of a test and a simulation.
In this case, the actuator operation can be adjusted more directly so as to have a low operating noise. However, it is necessary to fully consider the effect on the control system due to the further limitation of the motor output.

The vehicle body speed estimation means 43 for estimating the vehicle body speed of the vehicle equipped with the electric brake device is provided, and the motor control unit at the time of releasing the brake changes the overshoot amount according to the vehicle body speed, or the vehicle body speed is changed. When it is equal to or higher than the threshold value, the control of overshooting the motor angle may be canceled.
The threshold value is a threshold value arbitrarily determined by design or the like, and is determined by obtaining an appropriate threshold value by, for example, one or both of a test and a simulation.

If NVH is improved by overshooting, the responsiveness when braking again during overshoot may decrease.
When the vehicle body speed is high (fast), it is not necessary to consider NVH due to the influence of road noise and the like, and it is necessary to emphasize the reaction speed when the brake is stepped on again immediately after the brake is released. Therefore, for example, by changing the overshoot amount according to the vehicle body speed so that the overshoot amount decreases as the vehicle body speed increases, or by canceling the control of overshooting the motor angle when the vehicle body speed is equal to or higher than the threshold value. The risk of response delay can be reduced while improving NVH. Alternatively, in order to make the process simpler, it is possible to execute the control of overshooting when the vehicle body speed is substantially zero and not execute the process when the vehicle is running.

The electric brake device of the present invention includes a brake rotor, a friction material that generates a braking force in contact with the brake rotor, an electric motor, and a friction material operation that converts the output of the electric motor into a pressing force of the friction material. In an electric brake device including means and a control device for controlling the electric motor so that the brake force follows a given braking force command value, the control device has the braking force command value of zero or When the brake release request for releasing the braking force is recognized, the angle of the electric motor is adjusted so as to follow the motor angle command value that makes a state in which a defined clearance is provided between the friction material and the brake rotor. It has a brake release motor control unit to control, and this brake release motor control unit sets the angle of the electric motor to the motor angle command value when the brake force is set to zero from the state where the brake force is exerted. It has a function of following the motor angle command value after overshooting. Therefore, it is possible to improve the vehicle feeling and reduce the operating noise.

It is a figure which shows schematic the electric brake device which concerns on embodiment of this invention. It is a block diagram of the control system of the electric brake device. It is a block diagram which shows the structural example of a part of the control device of the electric brake device. It is a figure which shows the operation example at the time of the brake release of the electric brake device. It is a block diagram which shows the structural example of a part of the control device of the electric brake device which concerns on other embodiment of this invention. It is a block diagram of the control system of the electric brake device which concerns on still another Embodiment of this invention. It is a block diagram which shows the structural example of a part of the control device of the electric brake device. It is a figure which shows the example which obtains the overshoot characteristic by the characteristic of a control system in the control device. It is a block diagram of the control system of the electric brake device which concerns on still another Embodiment of this invention. It is a block diagram which shows the structural example of a part of the control device of the electric brake device. It is a figure which shows the torque limitation example of the control device. It is a figure which shows the other torque limitation example of the control device. It is a block diagram of the control system of the electric brake device which concerns on still another Embodiment of this invention. It is a flowchart which shows the control flow of the electric brake device which concerns on still another Embodiment of this invention. It is a figure which shows the operation example of the electric brake device of the conventional example. It is a figure which shows the operation example of the electric brake device of another conventional example.

The electric brake device according to the embodiment of the present invention will be described with reference to FIGS. 1 to 4. This electric braking device is mounted on a vehicle, for example.
As shown in FIG. 1, the electric brake device 1 includes an electric linear actuator DA, a power supply device 3, and a friction brake BR. First, the structures of the electric linear actuator DA and the friction brake BR will be described.

<Structure of electric linear actuator DA and friction brake BR>
As shown in FIG. 1, the electric linear actuator DA includes an actuator main body AH and a control device 2 described later. As shown in FIGS. 1 and 2, the actuator main body AH includes an electric motor 4, a deceleration mechanism 5, a linear motion mechanism 6 which is a friction material operating means, a parking brake mechanism 7, an angle sensor Sa, and a load sensor. It has Sb.

As shown in FIG. 1, when the electric motor 4 is configured by a permanent magnet type synchronous motor, it is suitable because it saves space, has high efficiency and high torque, but for example, a DC motor using a brush or a permanent magnet is not used. A reluctance motor, an induction motor, or the like can also be applied.

The speed reduction mechanism 5 is a mechanism for reducing the rotation of the electric motor 4, and includes a primary gear 12, an intermediate gear 13, and a tertiary gear 11. In this example, the reduction mechanism 5 decelerates 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 the rotation to the tertiary gear 11 fixed to the end of the rotation shaft 10. It is possible.

The linear motion mechanism 6 is a mechanism that converts the rotary motion output by the deceleration mechanism 5 into a linear motion of the linear motion portion 14 by the feed screw mechanism, and causes the friction material 9 to abut and separate from the brake rotor 8. The linear motion portion 14 is detented and is movably supported in the axial direction indicated by the arrow A1. A friction material 9 is provided at the outboard side end of the linear motion portion 14. By transmitting the rotation of the electric motor 4 to the linear motion mechanism 6 via the reduction mechanism 5, the rotational motion is converted into a linear motion, which is converted into the pressing force of the friction material 9 to generate a braking force. .. With the electric brake device 1 mounted on the vehicle, the outside of the vehicle in the vehicle width direction is referred to as the outboard side. The center side of the vehicle in the width direction is called the inboard side.

As the actuator 16 of the parking brake mechanism 7, for example, a linear solenoid is applied. A parking lock state is achieved by advancing the lock member 15 by the actuator 16 and fitting it into a locking hole (not shown) formed in the intermediate gear 13 to lock the intermediate gear 13 and prohibiting the rotation of the intermediate gear 13. To. By disengaging the lock member 15 from the locking hole, the intermediate gear 13 is allowed to rotate and is brought into an unlocked state.

As shown in FIG. 2, the angle sensor Sa detects the angle of rotation of the electric motor 4. As the angle sensor Sa, for example, it is suitable to use a resolver or a magnetic encoder because of high accuracy and high reliability, but various sensors such as an optical encoder can also be applied. Instead of using the angle sensor Sa, for example, in the control device 2 described later, angle sensorless estimation such as estimating the motor angle from the relationship between the voltage and the current of the electric motor 4 can be used.

The load sensor Sb detects the displacement or deformation of a predetermined portion on which the load of the linear motion mechanism 6 acts. As such a load sensor Sb, for example, a magnetic sensor, a strain sensor, a pressure sensor, or the like can be used. Instead of using the load sensor Sb, the control device 2 may perform load sensorless estimation from the motor angle, the rigidity of the electric brake device, the motor current, the efficiency of the electric actuator DA, and the like. Alternatively, it may be another external sensor such as a sensor that detects the wheel torque of the wheel on which the friction brake BR is mounted or the front-rear force of the vehicle on which the electric brake device 1 is mounted. Further, various sensors such as a thermistor may be separately provided according to the requirements.

As shown in FIG. 1, the friction brake BR has a brake rotor 8 that rotates in conjunction with the wheels of the vehicle, and a friction material 9 that comes into contact with the brake rotor 8 to generate braking force. The friction material 9 is arranged in the vicinity of the brake rotor. A mechanism can be used in which the friction material 9 is operated by the actuator main body AH to press the brake rotor 8 and generate a braking force by the frictional force. The brake rotor 8 and the friction material 9 may be, for example, a disc brake device using a brake disc and a caliper, or a drum brake device using a drum and a lining.

<Configuration of control device 2>
As shown in FIG. 2, each control device 2 controls the corresponding electric motor 4. A power supply device 3 and a higher-level ECU 17 which is a higher-level control means of each control device 2 are connected to each control device 2. The power supply device 3 supplies electric power to the electric motor 4 and the control device 2. As the power supply device 3, for example, a low voltage (for example, 12V) battery of a vehicle equipped with the electric brake device 1 may be applied.

As the upper ECU 17, for example, an electric control unit (Vehicle Control Unit, VCU) that controls the entire vehicle is applied. The upper ECU 17 has an integrated control function for each control device 2. The upper ECU 17 includes a command means 17a, and the command means 17a sets a target braking force command value for each control device 2 according to the output of a sensor that changes according to the operation amount of the brake operating means (not shown). Output. The command means 17a may be the brake operating means itself, or the command means 17a may, for example, determine braking in an autonomous driving vehicle and output a command value to each control device 2 without depending on the operation of the brake operating means. Is also possible.

Each control device 2 includes various control calculators that perform control calculations, a current sensor Sc, and a motor driver 18. The various control arithmetic units are composed of, for example, a processor such as a microcomputer, an arithmetic unit such as FPGA or ASIC, and peripheral circuits. The various control calculators include a braking force estimator 19, a rotational motion estimator 20, a current estimator 21, an actuator controller 22, and a command value generator 23.

The braking force estimator 19 has a function of estimating the actuator load (brake load) used for the control calculation from the output of the load sensor Sb. Alternatively, as described above, the braking force estimator 19 can be a sensorless estimator that obtains the actuator load without using sensors such as the load sensor Sb.

The rotary motion estimator 20 has a function of estimating parameters (calculation parameters) such as an angle, an angular velocity, and an electric angular phase used for control calculation from a sensor that detects the motion of the electric motor 4 such as an angle sensor Sa. The rotational motion estimator 20 has an angular velocity estimation function unit 24 as a function unit for estimating the angular velocity. The parameter may be, for example, a calculus process such as differentiating an angle to obtain an angular velocity, a state estimation observer using an actuator equation of motion for calculation, or a combination thereof. .. Alternatively, as described above, the rotational motion estimator 20 may be a sensorless estimator that estimates the electric angular velocity or the electric angular phase from the voltage and current of the electric motor 4, for example. It can also include disturbance observer functions such as actuator reaction force detection.

As the current sensor Sc, for example, a sensor including an amplifier that detects the voltage across the shunt resistance, a non-contact sensor that detects the magnetic flux around the energization path, or the like can be used.
The current estimator 21 has a function of estimating the current used for the control calculation from the output of the current sensor Sc. Alternatively, for example, the configuration may be such that the terminal voltage or the like of the element or the like constituting the motor driver 18 is detected, or the motor phase current may be estimated from the current on the primary side. Alternatively, the motor current can be feedforward controlled based on characteristics such as resistance or inductance of the electric motor 4 without providing any current sensor.

The actuator controller 22 calculates the operation amount so that the brake load or the like follows a predetermined command value. In the control calculation of the actuator controller 22, for example, the actuator load command value and the estimated value may be directly used for the feedback control calculation, or the braking force may be converted into another physical quantity such as a motor angle to perform the control calculation. good.

Further, for example, an arithmetic structure in which one or a plurality of minor feedback loops are provided, such as providing a motor current control loop in the feedback loop of the load feedback control, is preferable because fine control can be performed, but a single feedback is provided. The structure may be such that the motor operation amount is calculated in a loop. In addition, feedforward control may be performed based on the actuator characteristics estimated in advance, adaptive learning control or predictive control may be performed, or these may be used in combination as appropriate. In addition, for example, a function for limiting a predetermined operation amount for limiting the motor output or power consumption may be provided.

The command value generator 23 includes a brake force control command calculation unit 25 as a brake force control calculation function unit and a brake release command calculation unit 26 as a brake release motor control unit. The braking force control command calculation unit 25 generates an actuator operation command value when the braking force is exerted. The brake release command calculation unit 26 generates a command value for releasing the brake force. The command value generator 23 generates a command value used for actuator control from, for example, a command means 17a such as a brake pedal.

The command value is, for example, a braking force such as a brake load, a motor angle that can be a predetermined braking force derived from the rigidity of the electric brake device, a motor torque that can be a predetermined braking force derived from the efficiency of the electric brake device, or the like. The current, etc. may be used as a command value when controlling the braking force. Further, the motor angle or the like at which a predetermined clearance can be generated between the friction material 9 derived from the actuator equivalent lead or the like and the brake rotor 8 may be set as a command value when releasing the braking force.

The braking force control command calculation unit 25 is a command for exerting a predetermined braking force when the input of the command means 17a exceeds a predetermined threshold value, for example, when the brake pedal is depressed in excess of the play amount. You may output the value.
When the brake release command calculation unit 26 recognizes that the brake force command value is zero or the brake release request for releasing the brake force, the motor is in a state where a predetermined clearance is provided between the friction material 9 and the brake rotor 8. The motor angle is controlled so as to follow the angle command value. That is, the brake release command calculation unit 26 provides a sufficient clearance between the friction material 9 and the brake rotor 8 when the input of the command means 17a falls below a predetermined threshold value, for example, when the brake pedal is returned. The command value for controlling the motor angle may be output so as to be in the state of being able to be used.

At this time, in order to prevent chattering in the vicinity of the threshold value, hysteresis or the like may be appropriately provided between the threshold value when the braking force is exerted and the threshold value when the braking force is released. Alternatively, for example, a predetermined brake operation / release signal may be output from a higher-level ECU 17 such as a vehicle integrated control device (VCU), and the brake operation / release may be determined using the predetermined signal.

The brake release command calculation unit 26 includes an overshoot waveform generation unit 27. The overshoot waveform generation unit 27 can intentionally generate a command value that generates a relatively large overshoot as compared with normal control when controlling the motor angle for providing the predetermined clearance. .. When the brake force is set to zero from the state where the brake force is exerted, the brake release command calculation unit 26 overshoots the motor angle with respect to the motor angle command value by the overshoot waveform generation unit 27, and then sets the motor angle command value. It has a function to follow.

By providing a process to generate a command value that causes the overshoot when releasing the braking force, the braking force can be quickly reduced to zero, the brake drag feeling is reduced, and positioning is performed at the motor angle. It is preferable because the angular acceleration can be reduced and noise, vibration, and harshness (abbreviated as NVH) can be improved.

The overshoot amount OS (see FIG. 4) at this time is larger as the electric brake device 1 exerts a larger braking force, and the smaller the clearance amount between the friction material 9 and the brake rotor 8, the larger the ratio. There is a tendency to need to overshoot. Empirically, if the maximum clearance amount generated during overshoot is adjusted to be about 1.5 to 3 times the target clearance amount, a sufficient NVH improvement effect can be expected, but the actual characteristics are It shall be appropriately determined according to the motor angular velocity and the like when the electric brake device 1 is operated.

Further, for example, a function for adjusting the clearance between the friction material 9 and the brake rotor 8 after the brake release is completed may be separately provided according to the traveling state of the vehicle such as turning or traveling speed. At this time, in general, there is no problem even if the response speed is slower than that in the case of controlling the braking force, so that it is difficult for the operating noise to be generated, or it is necessary to adjust the clearance when the vehicle is running. In many cases, background noise such as road noise is large because the vehicle is in the middle of doing so. Therefore, the brake release command calculation unit 26 may be adjusted so as not to generate the overshoot as in the case of the above-mentioned brake release, or to have a relatively small overshoot amount.

The motor driver 18 controls the electric power supplied to the coil of the electric motor 4. The motor driver 18 constitutes, for example, a half-bridge circuit using a switch element such as a field effect transistor (abbreviated as FET), and PWM control in which the voltage applied to the motor is determined by the ON-OFF duty ratio of the switch element. If it is configured to perform the above, it will be inexpensive and have high performance. Alternatively, a transformer circuit or the like may be provided to perform PAM control.

In the half-bridge circuit, as a switching potential source for the H arm switch element that connects to the positive side of the power supply device 3, when the L arm switch element is turned on, charges are accumulated from a predetermined potential source. It is preferable to provide a charge circuit using a bootstrap capacitor that functions as a potential source applied to the gate when the H-arm switch element is turned on, because the motor driver 18 can be driven at low cost.

This figure only shows the concept of functional configuration, and elements not shown in the figure shall be provided as appropriate according to the requirements. Further, each functional block is provided for convenience, and can be appropriately integrated or divided according to the convenience of implementation. Further, the connection form of each function is shown as an example, and can be changed within a range that does not interfere with the above-mentioned functions.

<Example of controller configuration>
FIG. 3 shows a configuration example of the command value generator 23 in the example of FIG.
The command value generator 23 shown in FIG. 3 uses an actuator control command value as a motor angle, derives a limit value of a motor angle command from a predetermined motor angular acceleration, and generates an overshoot waveform using the limit value. show. The command value generator 23 includes a brake force control command calculation unit 25, a brake release command calculation unit 26, a brake release request determination unit 28, and a switching means 29.

<Brake force control command calculation unit 25>
The brake force control command calculation unit 25 has a brake force / motor angle conversion unit 25a, and the brake force / motor angle conversion unit 25a obtains a predetermined braking force from the brake force command value based on the rigidity of the electric brake device and the like. The obtained motor angle is derived and used as the command value of the braking force control command calculation unit 25. In addition to the example in this figure, for example, a brake load command value or the like may be used instead of the motor angle, and a motor current that can be a predetermined braking force is derived as a command value based on the efficiency of the electric brake device or the like. May be good.

<Brake release command calculation unit 26>
The brake release command calculation unit 26 includes a clearance motor angle conversion unit 30, an angle command limiter 27A which is an overshoot waveform generator, an angular velocity change amount calculation unit 31, angle calculation units 32 and 32, and a command value storage unit 33.
The clearance / motor angle conversion unit 30 derives a motor angle (motor angle command value) that can be a predetermined clearance based on the actuator equivalent lead or the like from the clearance command value, and uses this motor angle command value as the first release command value. And. The clearance command value may be a predetermined value, or may be a variable value which is appropriately changed based on the traveling state of the vehicle or the like.

The angular velocity change amount calculation unit 31 derives the change amount of the motor angular velocity from a predetermined angular acceleration limit value. When the control device 2 (FIG. 2) is operating at a predetermined calculation sampling rate t_smp, the angular velocity change amount calculation unit 31 may, for example, from the predetermined angular acceleration limit value α_lim, the angle with respect to each of the predetermined direction and the inversion direction. The amount of change Δω of the motor angular velocity at the acceleration limit value can be derived as Δω = α_lim · t_smp. The unit system of the equation shall be appropriately adjusted so that the equation holds with a predetermined conversion coefficient or the like.

From the estimated motor angular velocity estimated by the rotary motion estimator 20 (FIG. 2), that is, the current motor angular velocity, the angular velocity changed by ± Δω is derived, respectively, and the angular velocity is converted from the calculated sampling rate to the angle by the angle calculation units 32 and 32. Convert each. These converted values are added to the command values stored in the command value storage unit 33 up to the previous calculation cycle to obtain predetermined upper limit values and lower limit values. That is, the angle upper limit value θp = (ω + Δω) · t_smp + θz and the angle lower limit value θn = (ω−Δω) · t_smp + θz are obtained (θz: command value up to the previous calculation cycle).

The angle command limiter 27A limits the first release command value by the angle upper and lower limit values, sets the limited command value as the second release command value, and uses the second release command value as the brake release command calculation. It is the command value of the unit 26.

The brake release request determination unit 28 switches between the command value of the brake force control command calculation unit 25 and the command value of the brake release command calculation unit 26 in order to select an appropriate one as the final command value. The means 29 is switched. In the example of FIG. 3, the command value of the brake release command calculation unit 26 is selected. When switching from the previous calculation cycle occurs, the command value derivation flow on the side not selected shall be initialized as appropriate. The order of operations is not limited to this figure, and it is assumed that the final derived value is equivalent to this figure. For example, in the brake release command calculation unit 26, the amount of change in angle is derived from the amount of change in angular velocity, and is added or subtracted to the stored angle command value up to the previous calculation cycle. May be good.

<Example of electric brake operation>
FIG. 4 shows an operation example when the brake is released when the electric brake device according to this embodiment is applied. As shown in the figure, when the brake is released, the motor angle is overshooted with respect to the motor angle command value, and then the motor angle command value is followed to reduce the operating noise (improve NVH).

On the other hand, FIG. 15 shows an example of operating at a response speed equivalent to that when controlling the braking force as a conventional technique. In this example, when the braking force is zero and there is no load, a large angular acceleration for positioning is generated, so that a large operating noise is generated and NVH is deteriorated.
FIG. 16 shows an example of reducing the response speed when the brake is released as a conventional technique. In this example, the operation sound is the same as that of the electric brake operation example (FIG. 4) according to the present embodiment, but the time until the braking force becomes zero increases, and the vehicle feels as if the brake is released. The ring goes down.

<About action and effect>
According to the electric brake device 1 described above, the operation when the brake is released has a waveform that intentionally overshoots, so that the braking force is quickly reduced to zero to reduce the brake drag feeling and the brake standby position. By suppressing sudden acceleration / deceleration at the time of positioning to, it is possible to reduce the operating noise (improve NVH).

<About other embodiments>
In the following description, the same reference numerals will be given to the parts corresponding to the matters described in advance in each embodiment, and duplicate description will be omitted. When only a part of the configuration is described, the other parts of the configuration are the same as those described above unless otherwise specified. It has the same action and effect from the same configuration. Not only the combinations of the parts specifically described in each embodiment, but also the combinations of the embodiments can be partially combined as long as the combination does not cause any trouble.

The second release command value may be a value via a second-order or higher low-pass filter having overshoot and attenuation characteristics defined for the first release command value.
In FIG. 5, instead of the example of FIG. 3, as the brake release command calculation unit 26, a low-pass filter 34 having an overshoot characteristic is applied to the first release command value, and the filtered output is used as the second release command value. An example is shown. The overshoot type low-pass filter 34 of this example can be set, for example, by appropriately selecting an attenuation factor (attenuation characteristic) and a time constant in a low-pass filter having a secondary or higher eigenvalue.

6 and 7 show an example in which the overshoot controller 35 is provided in the actuator controller 22A.
The actuator controller 22A of this example includes a brake force control calculation unit 36 as a braking force control calculation function unit when performing braking force control, in addition to the functions of the actuator controller 22 (FIG. 2) of the above-described embodiment. A brake release control calculation unit 37 is provided as a brake release motor control unit when the brake is released.

<Brake force control calculation unit 36>
The braking force control calculation unit 36 performs a control calculation using a predetermined command value (actuator control command value) and feedback value. That is, the braking force control calculation unit 36 feedback-controls the electric motor so as to exert a predetermined braking force via a calculation parameter including a feedback gain set based on the first control system characteristic.

Although an example of using the motor angle command as the actuator control command value is shown, for example, a braking force command value or the like may be used instead of the motor angle command, and a predetermined braking force may be used based on the efficiency of the electric brake device or the like. The possible motor current may be derived and used as a command value. The feedback parameters shall be changed as appropriate according to the physical quantity of the command value. For example, when a braking force command value is used, the feedback parameter to be fed back is an estimated braking force. This braking force estimate is obtained from the braking force estimator.

<Brake release control calculation unit 37>
The brake release control calculation unit 37 performs a control calculation on the brake force control calculation unit 36 so as to generate a relatively large overshoot and to have a slow convergence characteristic. The control calculation may be based on a calculation parameter characteristic such as a control gain based on the adjustment of the characteristic of the control system that generates the desired overshoot shown in FIG. 8, or a dedicated control flow (described later). It may be according to FIG. 14).

As shown in FIGS. 6 and 7, the brake release control calculation unit 37 applies the braking force from the state in which the braking force is exerted via the calculation parameter including the feedback gain set based on the second control system characteristic. It has a function of feedback-controlling the electric motor 4 at a predetermined angle of zero. The second control system characteristic of the brake release control calculation unit 37 is set so that the overshoot amount is larger and the establishment time is longer than the first control system characteristic.

The overshoot controller 35 of the brake release control calculation unit 37 intentionally controls to generate a relatively large overshoot as compared with the normal control when controlling the motor angle for providing a predetermined clearance. Can be done.
FIG. 8 shows an example in which overshoot characteristics are obtained by the characteristics of the control system. Compared with the control characteristics of the brake force control calculation unit shown by the dotted line in FIG. 8, the characteristics of the control system of the brake release control calculation unit shown by the solid line in FIG. 8 are designed as a control system having a high peak gain and a low cutoff frequency. can do.

According to the configurations of FIGS. 6 to 8, since the control system characteristics can be directly adjusted, the actuator operation can be surely adjusted so as to have a low operating noise. However, processing such as appropriate initialization is required when the controller is switched.

FIG. 9 shows that the actuator controller is divided into a brake force controller 38, an operation amount limiter 39, and a motor current controller 40, and the operation amount limiter 39 is used for braking force control when normal braking force control is performed. An example of providing a motor torque limiting unit 41 and a motor torque limiting unit 42 when the brake is released when the brake is released is shown.

The motor torque limiting unit 41 during braking force control can be set, for example, based on restrictions such as motor output or power consumption. Alternatively, if the electric motor 4 has restrictions such as centrifugal force allowed from the durability of the rotor, a torque limit that does not exceed a predetermined angular velocity may be provided in the motor torque limiting unit 41 during braking force control. ..

When the motor torque limiting unit 42 releases the brake, when the braking force is reduced to zero from the state in which the braking force is exerted, the motor torque limiting unit 42 follows the angle of the electric motor 4 from the state in which the braking force becomes zero to the determined motor angle command value. Has a function of limiting the output of the electric motor 4 in between, and the output of the electric motor 4 limited by this function is larger than the maximum output of the electric motor 4 other than executing the limitation of the output of the electric motor 4. It is a small value.

The motor torque limiting unit 42 at the time of braking release has a function of limiting the motor torque to be relatively smaller than the limiting torque by the motor torque limiting unit 41 at the time of braking force control. By limiting the motor torque to a small value when the brake is released in this way, the angular acceleration decreases and overshoot occurs, but NVH is improved. The limit value by the motor torque limiting unit 42 when the brake is released shall be appropriately determined based on predetermined control design requirements.

FIG. 10 shows a configuration example of the operation amount limiter 39 in the configuration example of FIG. This will be described with reference to FIG.
<Motor torque limiting unit 41 during braking force control>
The motor torque limiting unit 41 during braking force control has a function of limiting the motor torque with respect to the motor torque which is the braking force operation amount for exerting a predetermined braking force calculated by the braking force controller 38 (FIG. 9). It is composed of a torque limiter 41a or the like having the above. Generally, in a region where the angular velocity is relatively low, the limiting torque is limited based on the maximum amount of current that can be energized, and the limiting torque can be made substantially constant except for the influence of iron loss or mechanical loss. In a region where the angular velocity is relatively high, the limit amount depends on the motor angular velocity and is limited based on a predetermined motor output or power consumption during motor drive, and it is necessary to limit the torque value to a smaller value as the angular velocity increases. be.

It is common to limit both of the above, but the motor torque limiting unit 41 during braking force control may be limited to only one of the above depending on the motor characteristics. Further, for example, when there are constraint conditions such as the centrifugal force of the rotor of the electric motor 4 or the detection limit angular velocity of the angle sensor Sa, the motor torque limiting unit 41 during braking force control further increases the angular velocity after exceeding a predetermined angular velocity. The torque may be limited to approximately zero so that it does not increase. Although FIG. 10 shows an example of limiting the torque, the limiting operation amount may be, for example, a motor current or a motor voltage.

<Motor torque limiting unit 42 when the brake is released>
The brake release motor torque limiter 42 is composed of a torque limiter 42a or the like having a function of limiting the motor torque when the brake is released to a value smaller than the torque limit of the brake force control motor torque limiter 41. To torque. By limiting the motor torque when the brake is released in this way, it takes time for the electric motor 4 which rotates at high speed when the brake is released to decelerate, so that a relatively large overshoot occurs. Further, according to the motor torque limiting unit 42 when the brake is released, the torque value is limited to a relatively small value, so that the torque value gradually converges to the target value after the overshoot.

11 and 12 show examples of torque limitation in FIG. 10, respectively. In FIGS. 11 and 12, the dotted line shows an example of torque limitation by the motor torque limiting unit at the time of braking force control, and the solid line shows an example of torque limiting by the motor torque limiting unit at the time of braking release. As shown in FIGS. 11 and 12, the limit torque at the time of releasing the brake is limited to a value smaller than the limit torque at the time of braking force control.

As shown in FIG. 13, the vehicle body speed estimation means 43 for estimating the vehicle body speed of the vehicle equipped with the electric brake device 1 is provided, and the brake release command calculation unit 26 changes the overshoot amount according to the vehicle body speed. Or, the control of overshooting the motor angle may be canceled when the vehicle body speed is equal to or higher than the threshold value.
FIG. 13 shows an overshoot amount adjusted according to a vehicle body speed (estimated vehicle body speed) estimated by a predetermined vehicle body speed estimation means 43 using, for example, a wheel speed sensor, an acceleration sensor, GPS, or the like in the configuration example of FIG. An example is shown in which the overshoot amount adjusting unit 44 is provided in the brake release command calculation unit 26.

Generally, the background noise due to road noise or the like is larger when the vehicle is traveling at high speed, and conversely, the background noise is smaller when the vehicle is running at low speed. In addition, the braking performance has a greater effect on the braking distance when the vehicle is traveling at high speed, and conversely, the braking distance is less affected when the vehicle is running at low speed. That is, it is necessary to improve the braking performance without worrying about NVH as the vehicle speed is higher, and it is necessary to emphasize NVH as the vehicle speed is lower.

If the overshoot when the brake is released is large, a response delay may occur if the brake is operated again while the brake is released. Therefore, the overshoot amount adjustment unit overshoots according to the traveling speed of the vehicle. Adjusting the amount may be preferable as it meets the above requirements.
In particular, it is very important to improve NVH when the vehicle is stopped, and it is not necessary to consider the risk of response delay at the time of re-braking. Therefore, the brake release command calculation unit 26 may detect the stopped state of the vehicle by the vehicle body speed estimation means 43 and execute the overshoot control only when the vehicle is stopped.

According to the configuration example of FIG. 13, the response delay while improving NVH by changing the overshoot amount according to the vehicle body speed or canceling the control of overshooting the motor angle when the vehicle body speed is equal to or higher than the threshold value. Risk can be reduced.
In addition, for the configuration example of FIG. 6 or 9, similarly to the above, the overshoot amount is changed according to the vehicle body speed, or the control of overshooting the motor angle when the vehicle body speed is equal to or higher than the threshold value is canceled. It is also possible to provide a process for processing.

For example, when the process is applied to the configuration example of FIG. 6, each parameter of the overshoot control unit 35 is adjusted so that the overshoot amount changes according to the vehicle body speed estimated by the vehicle body speed estimation means. May be good.
Further, for example, when the processing is applied to the configuration example of FIG. 9, the limiting torque of the motor torque limiting unit 42 at the time of brake release is changed so that the overshoot amount changes according to the vehicle body speed estimated by the vehicle body speed estimating means. It may be configured to adjust.

FIG. 14 shows an example of configuring the dedicated control flow. Steps S2 to S3 in FIG. 14 correspond to a brake force control calculation unit, and steps S4 to S11 correspond to a brake release control calculation unit. After the start of this process, the control device determines whether the braking operation is a braking request or a release request (step S1). Upon determining that the braking operation is the braking request, the braking force control calculation unit acquires the target braking force (step S2) and executes the braking force control (step S3). After that, this process ends.

In step S1, it is determined that the brake operation is the release request, and the brake release control calculation unit, which is the brake release motor control unit, determines whether or not the brake release operation is completed from the motor angle or the like (step). S4). This process ends when it is determined that the brake release operation has been completed. Upon determining that the brake has not been released, the brake release control calculation unit executes a brake depressurization operation of rotating the electric motor in a direction in which the friction material and the brake rotor are separated from each other (step S5).

From the state where the braking force becomes zero (step S6: yes), the brake release control calculation unit decelerates the electric motor at a predetermined angular acceleration (step S7), and the angular speed of the electric motor becomes zero (step). From S8: yes), the angle of the electric motor is controlled to follow the motor angle command value (target value) (steps S9 and S10). If it is determined in step S6 that the braking force is not yet zero (step S6: no), the process returns to step S5. If it is determined in step 8 that the angular velocity has not yet reached zero (step S8: no), the process returns to step S7. When the motor angle converges to the target value (step S10: yes), the brake release is completed (step S11), and then this process is terminated.

As another control flow, for example, a control flow or the like when a brake request is made by depressing the brake pedal again while the brake is released may be provided separately. Regarding the above, for example, it may be a process of forcibly shifting to the braking force control calculation, or it may be a process of shifting to the braking force control after the brake release is completed at a predetermined stage or to the end.

As the conversion mechanism portion of the linear motion mechanism 6, various screw mechanisms such as a planetary roller and a ball screw, a mechanism utilizing an inclination such as a ball lamp, and the like can be used.

Although the embodiments for carrying out the present invention have been described above based on the embodiments, the embodiments disclosed this time are exemplary in all respects and are not limiting. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

2 ... Control device 4 ... Electric motor 6 ... Linear mechanism (friction material operating means)
8 ... Brake rotor 9 ... Friction material 24 ... Angular velocity estimation function unit 25 ... Brake force control command calculation unit (brake force control calculation function unit)
26 ... Brake release command calculation unit (motor control unit when brake is released)
34 ... Low-pass filter 43 ... Vehicle body speed estimation means

Claims (7)

A brake rotor, a friction material that generates a braking force in contact with the brake rotor, an electric motor, a friction material operating means that converts the output of the electric motor into a pressing force of the friction material, and a given braking force. In an electric brake device including a control device that controls the electric motor so that the braking force follows a command value.
The control device is
When the brake force command value is zero or the brake release request for releasing the brake force is recognized, the motor angle command value is followed so that a defined clearance is provided between the friction material and the brake rotor. It has a motor control unit at the time of brake release that controls the angle of the electric motor as described above.
When the braking force is set to zero from the state in which the braking force is exerted, the motor control unit at the time of releasing the brake overshoots the angle of the electric motor with respect to the motor angle command value and then follows the motor angle command value. The motor control unit at the time of brake release has the function, and the motor angle command value in which the predetermined clearance is provided is set as the first release command value, and the motor control unit at the time of brake release is the first. An electric brake device that calculates a second release command value having an overshoot characteristic defined for the release command value of, and controls the electric motor to follow the second release command value . In the electric brake device according to claim 1 , the control device has an angular velocity estimation function unit that estimates the current angular velocity of the electric motor.
The brake release motor control unit sets an angular acceleration limit value determined from the second release command value, and accelerates / decelerates the angular velocity estimated by the angular velocity estimation function unit with the angular acceleration limit value. It has a function to calculate the angular velocity at time, and has a function to calculate the angular velocity.
The brake release motor control unit calculates the motor angle at the previous time when exercising at the calculated angular speed, sets the calculated motor angle as the limit value of the motor angle command value, and sets this limit value as the first limit value. An electric brake device in which the value used for the waterfall as one release command value is set as the second release command value. In the electric brake device according to claim 1 , the value of the second release command value is a value via a second or higher-order low-pass filter having overshoot and damping characteristics defined for the first release command value. The electric brake device. A brake rotor, a friction material that generates a braking force in contact with the brake rotor, an electric motor, a friction material operating means that converts the output of the electric motor into a pressing force of the friction material, and a given braking force. In an electric brake device including a control device that controls the electric motor so that the braking force follows a command value.
The control device is
When the brake force command value is zero or the brake release request for releasing the brake force is recognized, the motor angle command value is followed so that a defined clearance is provided between the friction material and the brake rotor. It has a motor control unit at the time of brake release that controls the angle of the electric motor as described above.
When the braking force is set to zero from the state in which the braking force is exerted, the brake release motor control unit overshoots the angle of the electric motor with respect to the motor angle command value and then follows the motor angle command value. The control device has a function, and the control device feedback-controls the electric motor so as to exert a predetermined braking force via a calculation parameter including a feedback gain set based on the first control system characteristic. Equipped with a control calculation function unit
The brake release motor control unit is set at a predetermined angle from the state in which the braking force is exerted to zero by the calculation parameter including the feedback gain set based on the second control system characteristic. It has a function to feedback control the electric motor.
An electric brake device set so that the overshoot amount is larger and the established time is longer than the first control system characteristic with respect to the second control system characteristic of the brake release motor control unit. A brake rotor, a friction material that generates a braking force in contact with the brake rotor, an electric motor, a friction material operating means that converts the output of the electric motor into a pressing force of the friction material, and a given braking force. In an electric brake device including a control device that controls the electric motor so that the braking force follows a command value.
The control device is
When the brake force command value is zero or the brake release request for releasing the brake force is recognized, the motor angle command value is followed so that a defined clearance is provided between the friction material and the brake rotor. It has a motor control unit at the time of brake release that controls the angle of the electric motor as described above.
When the braking force is set to zero from the state in which the braking force is exerted, the motor control unit at the time of releasing the brake overshoots the angle of the electric motor with respect to the motor angle command value and then follows the motor angle command value. The motor control unit at the time of releasing the brake has a function, and when the braking force is reduced to zero from the state where the braking force is exerted, the electric motor is rotated in a direction in which the friction material and the brake rotor are separated from each other. The electric motor is decelerated at a predetermined angular acceleration from the state where the braking force becomes zero, and the angle of the electric motor follows the motor angle command value from the state where the angular speed of the electric motor becomes zero. An electric braking device that has the function of controlling. A brake rotor, a friction material that generates a braking force in contact with the brake rotor, an electric motor, a friction material operating means that converts the output of the electric motor into a pressing force of the friction material, and a given braking force. In an electric brake device including a control device that controls the electric motor so that the braking force follows a command value.
The control device is
When the brake force command value is zero or the brake release request for releasing the brake force is recognized, the motor angle command value is followed so that a defined clearance is provided between the friction material and the brake rotor. It has a motor control unit at the time of brake release that controls the angle of the electric motor as described above.
When the braking force is set to zero from the state in which the braking force is exerted, the motor control unit at the time of releasing the brake overshoots the angle of the electric motor with respect to the motor angle command value and then follows the motor angle command value. The motor control unit at the time of releasing the brake has a function, and when the braking force is set to zero from the state where the braking force is exerted, the angle of the electric motor is set to the motor angle command value determined from the state where the braking force becomes zero. Has a function of limiting the output of the electric motor until it is made to follow, and the output of the electric motor limited by this function is the maximum of the electric motor other than executing the limitation of the output of the electric motor. An electric braking device whose value is smaller than the output. The electric brake device according to any one of claims 1 to 6 includes a vehicle body speed estimation means for estimating the vehicle body speed of a vehicle equipped with the electric brake device, and the brake release motor control unit is the vehicle body. An electric brake device that changes the amount of overshoot according to the speed, or releases the control of overshooting the motor angle when the vehicle body speed is equal to or higher than the threshold value.

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