JP6952528B2 - Electric brake device - Google Patents

Description

The present invention relates to an electric braking device used in a vehicle such as an automobile or various devices.

Conventionally, an actuator for an electric brake including an electric motor, a linear motion mechanism, and a speed reducer has been proposed (Patent Document 1). Further, an electric actuator including a planetary roller mechanism and an electric motor has been proposed (Patent Document 2).

Japanese Unexamined Patent Publication No. 06-327190 Japanese Unexamined Patent Publication No. 206-194356

For example, in an electric braking device using an electric linear actuator as in Documents 1 and 2, a half-bridge circuit that converts DC power of a battery into AC power is used as a motor driver. The half-bridge circuit includes an H-arm switch that connects to the positive side of the battery and an L-arm switch that connects to the negative side of the battery.
Further, in order to drive the motor driver at low cost, as a switching potential source of the H arm switch, when the L arm switch is turned on, electric charge is accumulated from a predetermined potential source and the H arm switch is turned on. In some cases, a charge circuit using a bootstrap capacitor that functions as a potential source applied to the gate may be provided.

However, when the braking force is released when the braking operation is released and the electric braking device is put into the standby state, if the bootstrap capacitor that drives the half-bridge circuit is discharged, the switch element on the H arm side can be turned on. Therefore, the motor cannot be driven promptly the next time a brake operation is input, and the brake response may be delayed.
In particular, when it is possible that the brakes are not applied for a long time, such as when driving on a highway, the above problem is likely to occur.
As a countermeasure against the above-mentioned problems, increasing the capacity of the bootstrap capacitor or providing an insulating structure for preventing discharge may cause problems such as an increase in cost and mounting space.

Further, in the electric brake device as described above, a digital arithmetic unit (microcomputer, etc.) is generally used to implement complicated arithmetic operation at low cost, but when trying to control the electric motor to a predetermined angle, it is necessary to obtain resolution and sampling. Due to this, minute fluctuations may occur. In particular, in the no-load state when the brake is released as described above, the deterioration of NHV (Noise Harshness Vibration) due to the vibration may become a problem due to the influence of the backlash of the mechanical coupling portion and the like.
As a countermeasure against the above-mentioned problems, for example, when an arithmetic unit having extremely minute resolution and sampling, or an analog element that does not require sampling or the like is used, cost may become a problem. Alternatively, if the mechanical coupling portion has a structure without backlash, the manufacturing cost may become a problem.

Alternatively, when the motor control is completely stopped as a countermeasure against the NHV, there is a problem that the bootstrap capacitor is likely to be discharged. In addition, when the electric motor is rotated by an external force such as vibration due to unevenness of the road surface, the position changes from the original brake standby state, so that the gap between the friction material and the brake rotor in the brake standby state is reduced. Unintended drag torque may be generated or expanded to cause a response delay during the next braking operation.

An object of the present invention is to provide an electric braking device capable of reliably charging a switch power source, promptly operating the next braking operation, and improving noise and vibration when there is no load.

The electric brake device of the present invention includes a brake rotor 31, a friction material 32 that comes into contact with the brake rotor 31 to generate a braking force, and a friction material operating means (2) that operates the friction material 32 by driving an electric motor 6. ), A control device 5 that controls the output of the electric motor 6 so as to follow a given brake command value, and a DC power supply device 3 that applies power to the electric motor 6.
The control device 5
A switch means 21 for controlling the connection state between the coil end of the electric motor 6 and the power supply device 3 and
A switch power supply 22 having a power storage function and functioning as a power source for switching at least a part of the switch means 21.
A charging means 24 for storing electric power in the switch power supply 22 in a predetermined switching pattern of the switch means 21 and a charging means 24.
When the magnitude of at least one of the braking force command value and its differential value becomes smaller than a predetermined value, the brake release request determination function unit 14 for determining that the operation for requesting the brake release has been performed, and the brake release request determination function unit 14.
When it is determined that the operation requesting the brake release has been performed, the friction material operating means (2) is driven to a predetermined brake release state, and the angle of the electric motor 6 at this time and its differential value The release completion determination function unit 15 that determines that the transition to the brake release state has been completed from at least one of them, and
When it is determined that the transition to the release state is completed, at least the electric motor 6 in a stationary state is not spontaneously driven, and the switch means 21 is turned into the switch power supply 22 by storing electricity in the switch power supply 22. It has a brake standby function unit 16 that maintains a predetermined switching pattern that can be stored.
It is characterized by that.

According to this configuration, when it is determined that the transition to the release state is completed, the brake standby function unit 16 does not voluntarily drive the electric motor 6 in at least a stationary state, and the switch means 21. Is maintained in a predetermined switching pattern that can be stored in the switch power supply 22 by the charging means 24. Therefore, the switch power supply 22 is surely charged, and the switch power supply 22 can be quickly operated at the next braking operation. Further, since the voltage condition is not driven spontaneously, noise and vibration at no load, so-called NHV, can be improved.
The above "predetermined value" is provided for each of the braking force command value and its differential value. Further, the above-mentioned "predetermined value", each of the following "predetermined values" and "predetermined" values referred to in this specification are values appropriately determined by a test or design.

In the electric brake device of this configuration
The switch means 21 is a switch circuit provided with a pair of an L-arm switch circuit 21L and an H-arm switch circuit 21H for each coil end of the electric motor 6.
The L-arm switch circuit 21L includes a first input / output terminal 25La connected to the coil end of the electric motor 6, a second input / output terminal 25Lb connected to the minus side of the power supply device 3, and the first input / output terminal 25Lb. A transistor element 25 having a switching terminal 25Lc to which both input / output terminals 25La and 25Lb are connected by inputting a positive potential to the second input / output terminal 25Lb causes the negative side of the power supply device 3 and the power supply device 3 to be connected. It is a switch circuit unit that controls the connection state with the coil end of the electric motor 6.
The H-arm switch circuit 21H includes a first input / output terminal 25Ha connected to the positive side of the power supply device 3, a second input / output terminal 25Hb connected to the coil end of the electric motor 6, and the first input / output terminal 25Hb. The positive side of the power supply device 3 and the electric power device 3 are provided by a transistor element 25H having a switching terminal 25Hc for connecting both input / output terminals 25Ha and 25Hb by inputting a positive potential to the second input / output terminal 25Hb. It is a switch circuit unit that controls the connection state with the coil end of the motor 6.
The switch power supply 22 is a capacitor to which the second input / output terminal 25Hb of the transistor element 25H in the H arm switch circuit 21H is connected as an electrical reference potential.
The charging means 24 is a charging circuit that accumulates electric charge in the switch power supply 22 composed of the capacitor when the L arm switch circuit 21L is in a connected state.
The brake standby function unit 16 keeps all the L arm switches 21L in a constantly connected state and all the H arm switches 21H in a constantly disconnected state.
You may do so.

In the case of this configuration, since all the switch circuits 21H and 21L of the switch means 21 are kept in a constant state of being on or off, switching loss can be reduced and power consumption can be expected to be reduced.
Specifically, in the state where the brake is released, the state of the switch means 21 including the half bridge circuit in the motor driver 13 of the electric braking device is turned on by the L arm switch circuit 21L and turned off by the H arm switch circuit 21H. It is maintained in a constant state, and the switch power supply 22 composed of a bootstrap capacitor used as a switching voltage of the H-arm switch circuit 21H is maintained in a charged state.
The brake release request determination function unit 14 determines the request to release the brake from the brake command of the command means (brake pedal, etc.) 4 and the amount of change thereof, and the electric brake device waits at a predetermined time based on the motor angle and the motor angular speed at that time. The brake release completion determination function unit 15 determines whether or not the vehicle has moved to the position, and in that state, the brake standby function unit 16 maintains the state of the switch means 21 composed of the half bridge circuit to bring the brake standby state. ..

By keeping the L-arm switch circuit 21L on and the H-arm switch circuit 21H off as described above, the switch power supply 22 composed of the bootstrap capacitor is constantly charged, and when a request for braking is requested, the switch power supply 22 is constantly charged. It is possible to respond promptly.
By always turning on all L-arm switch circuits 21L and always turning off H-arm switch circuits 21H, switching is not performed, so switching loss due to floating capacitance of transistor elements 25H and 25L such as FETs occurs. However, the standby power can be reduced.
Since the motor terminal voltages u, v, and w are all the same voltage, the electric motor 6 is not driven spontaneously, and minute chattering due to sensor resolution and sampling does not occur. It can be quieted.
When the electric motor 6 is rotated from the outside due to vibration or the like, it is possible to prevent the electric motor 6 from suddenly separating from the standby position due to the generation torque generated by the electric motor 6, and the follow-up control is executed again. It becomes easy to return to the standby position.

In the electric brake device of the present invention, the release completion determination function unit 14 determines the deviation of the motor angle with respect to the motor angle target value at which a predetermined gap may be generated between the friction material 32 and the brake rotor 31. It may be determined that the brake release is completed when the absolute value is not more than a predetermined value and the absolute value of the motor angular velocity is not more than a predetermined value.

Further, in the electric brake device of the present invention, the release completion determination function unit 14 determines the motor angle with respect to the motor angle target value at which a predetermined gap may be generated between the friction material 32 and the brake rotor 31. A counter 14a for measuring the duration of a state in which the absolute value of the deviation is equal to or less than a predetermined value may be provided, and when the value of the counter 14a exceeds the predetermined value, it may be determined that the brake release is completed.

In the electric brake device of the present invention, when the fluctuation of the motor angle becomes larger than a predetermined amount during execution, the brake standby function unit 16 releases the brake standby function and puts the friction into a predetermined brake release state. The material 32 may be driven.
With this configuration, when the gap amount during standby fluctuates due to the influence of vibration or the like, it is possible to prevent unintended drag torque generation and response delay by appropriately correcting and maintaining the gap amount.

In the electric brake device of the present invention, there is an angle estimation means (9) for estimating the angle of the electric motor 6, and the control device 5 has a cogging torque estimation function unit 11a for estimating the cogging torque from the estimated angle. It may have a standby position adjusting function unit 11b whose angle command value is the motor angle at which the estimated cogging torque becomes substantially zero when shifting from the braking state to the braking releasing state.
When the function of the brake standby function unit 16 is executed in the phase in which a relatively large cogging torque is generated, the motor is rotated by the cogging torque. However, when the cogging torque estimation function unit 11a and the standby position adjustment function unit 11b are provided, the problem that the motor is rotated by the cogging torque can be prevented by making the motor stand by at a motor angle where the cogging torque is zero or sufficiently small in advance. can do.

The electric brake device of the present invention includes a brake rotor, 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 by driving an electric motor, and a given brake command. In an electric brake device including a control device that controls the output of the electric motor so as to follow a value and a DC power supply device that applies power to the electric motor, the control device is a coil end of the electric motor. The switch means for controlling the connection state with the power supply device, the switch power supply having a power storage function and functioning as a power source for switching at least a part of the switch means, and the switch in a predetermined switching pattern of the switch means. When the charging means for accumulating power in the power source and at least one of the braking force command value and its differential value become smaller than a predetermined value, it is determined that the operation for requesting the brake release has been performed. Brake release request judgment function unit and
When it is determined that the operation requesting the brake release has been performed, the friction material operating means is driven to a predetermined brake release state, and the angle of the electric motor at this time and at least one of its differential values are used. The release completion determination function unit that determines that the transition to the brake release state has been completed, and when it is determined that the transition to the release state has been completed, at least the electric motor in the stationary state is not spontaneously driven. In addition, since the switch means has a brake standby function unit that maintains the switch means in a predetermined switching pattern that can be stored in the switch power supply by the charging means, the switch power supply is surely charged and operates promptly at the next braking operation. It can also be made to improve noise and vibration when there is no load.

It is a block diagram which shows the conceptual structure of the electric brake device which concerns on 1st Embodiment of this invention. It is an enlarged view of the upper part of FIG. It is an enlarged view of the lower part of FIG. It is a flow chart which shows the control operation example of the electric brake device. It is sectional drawing which shows the specific example of the friction brake mechanism and the linear actuator of the electric brake device. It is a block diagram which shows the conceptual structure of the electric brake device which concerns on other embodiment of this invention.

A first embodiment of the present invention will be described with reference to FIGS. 1 to 5. 2 and 3 show enlarged upper and lower parts of FIG. 1, respectively. In FIG. 1, the electric brake device includes a friction brake mechanism 1, a linear actuator 2 which is a friction material operating means, a power supply device 3, and a linear actuator so as to follow a command value given by a command means 4. A control device 5 for controlling the output of the electric motor 6 of 2 is provided.

<< Friction Brake Mechanism 1 >>
The friction brake mechanism 1 is composed of, for example, a brake rotor 31 and a friction material 32 that is brought into contact with the brake rotor 31 to generate a braking force, as shown in FIG. The friction brake mechanism 1 may be a disc brake device using, for example, a brake disc and a caliper, or a drum brake device using a drum and a lining, as the brake rotor 31 and the friction material 32.
In this embodiment, the linear actuator 2 is used as the friction material operating means for operating the friction material 32, but the friction material operating means is other than the linear operation such as operating the friction material 32 in an arc locus. The friction material 32 may be brought into contact with the brake rotor 31 in operation.

<< Linear actuator 2 >>
The linear actuator 2 includes an electric motor 6 and a linear motion mechanism 7 that converts the rotational output of the electric motor 6 into a linear reciprocating operation. In the example of FIG. 5, the linear actuator 2 includes a reduction gear 33 including a gear train of spur gears for decelerating the output of the electric motor 6, and the rotational output of the reduction gear 33 is linearly reciprocated by the linear motion mechanism 7. Convert to. In addition to this, the speed reducer 33 may be a worm gear, a planetary gear, or the like, and may not necessarily be provided.

As shown in FIG. 1, in addition to the above, the linear actuator 2 includes a load sensor 8 for detecting the axial load of the linear motion mechanism 7 and an angle sensor for detecting the motor angle (rotation angle of the rotor) of the electric motor 6. Has 9 and. Further, various sensors (not shown) such as a thermistor may be separately provided as needed.
The electric motor 6 is preferably a permanent magnet synchronous motor, which is considered to be suitable because it saves space and has a high torque. For example, a DC motor using a brush, a reluctance motor not using a permanent magnet, an induction motor, or the like. Can also be applied.
The linear motion mechanism 7 may use various screw mechanisms such as planetary roller screws and ball screws, and various mechanisms such as ball lamps that convert rotational motion into linear motion by means of a circumferentially inclined portion formed on the rotation axis. can.

As the angle sensor 9, for example, a resolver, a magnetic encoder, or the like is used, and according to these, it is considered to be suitable because of high accuracy and high reliability, but various sensors such as an optical encoder can also be applied. Alternatively, instead of using the angle sensor 9 as the angle estimation means, it is possible to use an angle sensorless estimation (not shown) such that the motor angle is estimated from the relationship between the voltage and the current in the control device 5, for example.

As the load sensor 8, for example, a magnetic sensor, a strain sensor, a pressure sensor, or the like that detects displacement or deformation can be used. Alternatively, the load sensorless estimation may be used in the control device 5 from the motor angle, the rigidity of the electric braking device, the motor current, the linear actuator efficiency, and the like without providing the load sensor 8 as the load estimation. Alternatively, various sensors outside the electric brake device, such as a sensor that detects the wheel torque of the wheel on which the electric brake device is mounted and the front-rear force of the vehicle equipped with the electric brake device, may be used.

<< Power supply unit 3 and command means 4 >>
The power supply device 3 has a function of storing electricity such as a battery and supplying DC power, and may be a device that serves as a power source for the entire vehicle or a device that serves as a dedicated power source for the electric brake device.
The command means 4 is a means for operating the brake on / off request operation of the brake pedal or the like, and outputs a command from, for example, a pedal stroke sensor provided on the brake pedal. The command of the command means 4 may be given to the control device 5 of the electric brake device via a higher-level ECU such as a VCU (not shown). The command means 4 may be a part of the automatic driving function unit in a vehicle having a function of performing automatic driving.

<< Configuration of control device 5 >>
The control device 5 has a main brake control 11, a switching pattern determination function unit 12, and a motor driver 13 as a basic configuration, and in addition, a brake release request determination function unit 14, a brake release completion determination function unit 15, It also has a brake standby function unit 16.
Each of the functional units 11, 12, 14, 15, and 16 having the control device 5 is composed of, for example, a microcomputer, an arithmetic unit such as an FPGA or an ASIC, and peripheral circuits, which is considered to be inexpensive, high-performance, and suitable.

<Main brake control function unit 11>
The main brake control function unit 11 performs a control calculation for controlling the electric motor 6 so that the estimated braking force estimated from the load sensor 8 or the like follows the braking force command value requested by the command means 4. .. For the control calculation, for example, feedback control that directly uses the braking force command value and the estimated value may be used, or the braking force may be converted into another physical quantity such as an angle to perform the control calculation. Further, the feedback control calculation may have a calculation structure in which a plurality of minor feedback loops are provided so as to provide a motor current control loop in the braking force control loop, and the motor operation amount is calculated by a single feedback loop. It may be a structure. In addition, feedforward control or the like can be used, or can be used in combination as appropriate.

Further, the main brake control function unit 11 has a function of following and controlling the braking force in order to reduce the drag torque when the brake is released, and when the braking force is released, the friction material of the friction brake mechanism 1 is used. It is preferable to provide a function of controlling the linear motion actuator 2 at a position where a predetermined clearance is provided between 32 (see FIG. 3) and the brake rotor 31. The above function may be a function of estimating the position of the linear actuator 2 from, for example, the motor angle and the equivalent lead of the linear actuator 2, which is considered to be preferable because of low cost. A position sensor (not shown) for detecting the position may be separately provided.

<Switching pattern determination function unit 12>
The switching pattern determination function unit 12 has a function of determining a connection / disconnection pattern between the coil end of the electric motor 6 and the power supply device 3 in the motor driver 13 based on the motor operation amount calculated mainly by the main brake control function unit 11. Has. For example, when the power supply device 3 having a DC voltage of Vdc (plus side: + Vdc, minus side: GND) is used and the voltage of a predetermined motor terminal is Vn, the ratio is approximately Vn / Vdc within a predetermined time. It may have a function of connecting the time to be on the plus side (+ Vdc) and connecting the time when the ratio is approximately (1-Vn / Vdc) to the minus side (GND) to generate a pulse signal.

<Motor driver 13>
The motor driver 13 includes a switch means 21 that controls the connection state between the coil end of the electric motor 6 and the power supply device 3, and a switch that has a power storage function and functions as a power source for switching at least a part of the switch means 21. Power is supplied to the power supply 22, the switch control circuit 23 that gives a switch control signal to the transistor elements 25H and 25L that are the switch elements constituting the switch means 21, and the switch power supply 21 in a predetermined switching pattern of the switch means 21. It has a charging means 24 for accumulating. The switch control circuit 23 gives a switch control signal to the transistor elements 25H and 25L according to the switching pattern output from the switch pattern determination function unit 12.

<Switch means 21>
Specifically, the switch means 21 is a switch circuit provided with a pair of an L-arm switch circuit 21L and an H-arm switch circuit 21H at the coil ends u, v, and w of the electric motor 6, respectively. In the form, it is a half-bridge circuit.
The L-arm switch circuit 21L is a switch circuit unit that controls the connection state between the negative side of the power supply device 3 and the coil ends u, v, w of the electric motor 6 by a transistor element 25L such as a FET. The transistor element 25L includes a first input / output terminal 25La connected to the coil ends u, v, w of the electric motor 6, a second input / output terminal 25Lb connected to the negative side of the power supply device 3, and the above. It has a switching terminal 25Lc that connects both input / output terminals 25La and 25Lb by inputting a positive potential to the second input / output terminal 25Lb.
The H-arm switch circuit 21H is a switch circuit unit that controls a connection state between the positive side of the power supply device 3 and the coil ends u, v, w of the electric motor 6 by a transistor element 25H such as an FET. The transistor element 25H includes a first input / output terminal 25Ha connected to the positive side of the power supply device 3, a second input / output terminal 25Hb connected to the coil ends u, v, w of the electric motor 6, and the above. It has a switching terminal 25Hc that connects both input / output terminals 25Ha and 25Hb by inputting a positive potential to the second input / output terminal 25Hb.

<Switch power supply 22 and charging means 24>
The switch power supply 22 is a capacitor in which the second input / output terminal 25Hb of the transistor element 25H in the H arm switch circuit 21H is connected as an electrical reference potential, that is, a so-called bootstrap capacitor.
The charging means 24 is a charging circuit that accumulates electric charges in the switch power supply 22 composed of the capacitor when the L arm switch circuit 21L is in a connected state, and is used as a potential source (not shown) having a predetermined potential V2. It is composed of a circuit connected to the switch power supply 22 via a diode 24a. The potential V2 may be at least a sufficient potential for connecting the terminals 25La and 25Lb and 25Ha and 25Hb of the transistor element to the switching terminals 25Lc and 25Hc of the transistor elements 25L and 25H, and is common to, for example, the potential V1. The potential may be equal to V1 applied from the power supply device 3, or, for example, when the power supply device 3 is a general vehicle low-voltage power supply 12V, the voltage is stepped down to + 5V, + 3.3V, etc. for a circuit such as a microcomputer. The potential may be lower than V1.

<Brake release request determination function unit 14>
The brake release request determination function unit 14 is a means for determining that "an operation requesting brake release has been performed" when at least one of the brake force command value and its differential value becomes smaller than a predetermined value. Is.
The brake release request determination function unit 14 brakes based on, for example, when the braking force command value falls below a predetermined value, when the amount of decrease in the braking force command value falls below a predetermined value, or when these are used in combination. It may have a function of determining whether or not the cancellation of is requested. Alternatively, for example, like a VCU in a vehicle, a higher-level ECU that generates a braking force command value is provided, a brake release request signal is separately transmitted from the higher-level ECU, and a request to release the brake upon receiving the brake release request. It can also be configured to make a judgment.

<Release completion judgment function unit 15>
When the release completion determination function unit 15 determines that the brake release is requested, the linear actuator 2 which is the friction material operating means is driven to a predetermined brake release state, and the electric motor 6 at this time From at least one of the angle and its differential value, it is judged that the transition to the brake release state is completed.
The release completion determination function unit 15 has a predetermined position such as a position where a predetermined clearance can be provided between the friction material 32 of the friction brake mechanism 1 and the brake rotor 31, for example, when the brake release is required. It has a function to determine whether the brake release state has been achieved.
The judgment is that, for example, when the motor angle is controlled to a position where a predetermined gap (clearance amount) can be obtained, the magnitude of the deviation between the angle command value and the estimated motor angle is less than the predetermined value, or the magnitude of the motor angular velocity. It may be determined that the brake release is completed when is less than the predetermined value or based on the predetermined condition in which these are used together.
The motor angular velocity may be estimated by, for example, a state estimation observer (not shown), or the transition of the motor angle within a predetermined time may be used as a physical quantity substantially equivalent to the angular velocity.

To show a specific example, the release completion determination function unit 14 has an absolute deviation of the motor angle with respect to a motor angle target value at which a predetermined gap can be generated between the friction material 32 and the brake rotor 31. It may be determined that the brake release is completed when the value is not more than a predetermined value and the absolute value of the motor angular velocity is not more than a predetermined value.

In addition to this, in the release completion determination function unit 14, the absolute value of the deviation of the motor angle is a predetermined value with respect to the motor angle target value at which a predetermined gap may be generated between the friction material 32 and the brake rotor 31. A counter 14a (see FIG. 2) for measuring the duration of the following states may be provided, and when the value of the counter 14a exceeds a predetermined value, it may be determined that the brake release is completed.

<Brake standby function unit 16>
When it is determined that the transition to the released state is completed, the brake standby function unit 16 does not voluntarily drive the electric motor 6 in at least the stationary state, and the switch means 21 is charged by the charging means 24. It is maintained in a predetermined switching pattern that can be stored in the switch power supply 22.
Specifically, the brake standby function unit 16 determines that the brake release request function unit 14 has requested the brake release, and the brake release completion determination function unit 15 determines that the brake release has been completed. The switching pattern determination function unit 12 may have a function of generating a predetermined switching pattern.

The brake standby function unit 16 releases the brake standby function and drives the friction material 32 to a predetermined brake release state when the fluctuation of the motor angle becomes larger than a predetermined amount during execution. May be good.
With this configuration, when the gap amount during standby fluctuates due to the influence of vibration or the like, it is possible to prevent unintended drag torque generation and response delay by appropriately correcting and maintaining the gap amount.

<< Outline of the operation of the above configuration >>
When the brake is released, the state of the switch means 21 composed of the half bridge circuit in the motor driver 13 of the electric brake device is maintained in a constant state in which the L arm switch circuit 21L is on and the H arm switch circuit 21H is off. Then, the switch power supply 22 composed of the bootstrap capacitor used as the switching voltage of the H-arm switch 21H is maintained in a charged state.
The brake release request determination function unit 14 determines the request to release the brake from the brake command of the command means (brake pedal, etc.) 4 and the amount of change thereof, and the electric brake device is set to a predetermined standby position based on the motor angle and angular speed at that time. The brake release completion determination function unit 15 determines whether or not the system has shifted to, and in that state, the brake standby function unit 16 executes the state maintenance of the switch means 21 composed of the half bridge circuit to bring the brake standby state.

<< Details of the operation of the above configuration and the configuration of each part >>
The motor driver 13 constitutes a switch means 21 including a half-bridge circuit using transistor elements 25H and 25L such as FETs as switch elements as described above, and for example, PWM control for determining a motor applied voltage according to a predetermined duty ratio. It is configured to perform. This makes it inexpensive and has high performance, which is considered to be suitable. Alternatively, a transformer circuit or the like may be provided to perform PAM control. The switching pattern for performing the PWM control and the PAM control is performed by the switching pattern determination function unit 12.
Further, among the half-bridge circuits constituting the switch means 21, the L-arm switch circuit 21L is turned on as a switching potential source for the transistor element 25H of the H-arm switch circuit 21H that connects to the positive side of the power supply device 3. Charging means, which is a charging circuit using a switch power supply 22 composed of a bootstrap capacitor that functions as a potential source applied to the gate when the H-arm switch circuit 21H is turned on by accumulating electric charges from a predetermined potential source when the electric charge is turned on. Since 24 is provided, the motor driver 13 can be driven at low cost, which is preferable.

At this time, if the motor driver 13 is not switched or the on time of the L arm switch 21L continues to be short, the charge state of the switch power supply 22 composed of the bootstrap capacitor becomes insufficient, and the H arm switch circuit 21H is turned on. There may be problems that cannot be done. Therefore, the switching pattern determination function unit 12 switches the L-arm switch circuit 21L with a sufficiently long on-time so that the charge state of the switch power supply 22 composed of the bootstrap capacitor is sufficient for controlling the H-arm switch circuit 21H. It is preferable to set it in the pattern. In particular, when the L-arm switch circuit 21 is always on and the H-arm switch circuit 21H is always off, the switch power supply 22 composed of the bootstrap capacitor can be surely maintained in a good charge state, and is accompanied by switching. Since no loss occurs, it is considered to be particularly suitable. Further, at this time, since the electric motor 6 is not driven spontaneously, the operating noise accompanying the motor sway is not generated, and the NHV can be improved. In particular, for example, when the linear actuator 2 has a mechanical coupling portion such as a speed reducer 33 (see FIG. 3) made of parallel gears or the like, a slight swing occurs due to the influence of backlash or the like in a no-load state when the brake is released. On the other hand, since a relatively loud operating noise is generated, the NHV may be greatly improved.

Further, when the electric motor 6 is in the constant switching pattern state, for example, when an external force is applied to the electric motor 6 due to vibration of a vehicle equipped with an electric brake, the electric motor 6 generates power to generate a load torque, so that switching is stopped, for example. Compared to such a case, the electric motor 6 is less likely to be rotated by an external force. Therefore, for example, it is possible to prevent the motor from deviating from the predetermined standby angle due to the external force of the motor or the like, and even if the motor departs, it is possible to return to the original standby position relatively easily.

<< Example of operation flow of brake standby function unit 16 etc. >>
FIG. 4 shows an example when the brake standby function unit 16 and the like execute in the example of FIG.
Step S. In 1, for example, when the braking force command value is less than the predetermined value, when the amount of decrease and change of the braking force command value is less than the predetermined value, or when the brake is released based on the predetermined condition in which these are used together, the brake is requested to be released. The brake release request determination function unit 14 determines whether or not the brake is released.
If the brake is not required to be released, step S. Proceed to step 5, the execution of the brake control is continued, and step S. Make the judgment of 1.
Step S. In 2, for example, when the magnitude of the deviation between the angle command value and the estimated motor angle is less than the predetermined value, the magnitude of the motor angular velocity is less than the predetermined value, or the brake is released based on the predetermined condition in which these are used together. The brake release determination function unit 15 determines whether or not the above is completed.

Step S. If it is determined in step 2 that the brake release is complete, step S. Proceed to 3. Step S. In No. 3, when the brake release is requested and the brake release is completed, all the H arm switch circuits 21H are turned off and all the L arm switch circuits 21L are turned on for the switching pattern of the motor driver 13. Set to. The switching pattern may be at least a switching pattern in which the switch power supply 22 including the bootstrap capacitor of the motor driver 13 of FIG. 1 can be sufficiently charged, but as shown in this figure, the swarm switch circuits 21H and 21L are turned on-. Since the off operation is not performed, the loss due to switching can be reduced, which is considered to be suitable.
At this time, step S. When the electric motor 6 is rotated by an external force such as vibration of a vehicle equipped with an electric brake device while the process of 3 is being executed, the step S. In step 2, it is determined that the brake release has not been completed, and step S. Proceeding to No. 4, the electric motor is quickly controlled to follow the target angle again.

According to the electric brake device of this embodiment, by keeping the L-arm switch circuit 21L on and the H-arm switch circuit 21H off in this way, the switch power supply 22 composed of the bootstrap capacitor is constantly charged. When a request to apply the brake is made, it can be promptly responded.
By always turning on all L-arm switch circuits 21L and always turning off H-arm switch circuits 21H, switching is not performed, so switching loss due to floating capacitance of transistor elements 25H and 25L such as FETs does not occur. , Standby power can be reduced.
Since all the motor terminal voltages are the same, the electric motor 6 is not driven spontaneously, and minute chattering or the like due to sensor resolution or sampling does not occur, so that the operating noise can be made quieter.
When the electric motor 6 is rotated from the outside due to vibration or the like, it is possible to prevent the electric motor 6 from suddenly separating from the standby position due to the generation torque generated by the electric motor 6, and the follow-up control is executed again. It becomes easy to return to the standby position.

<< Other Embodiments >>
FIG. 6 shows another embodiment of the present invention. This embodiment is the same as the first embodiment shown in FIGS. 1 to 5, except for the matters described in particular.
This embodiment shows an example in which the brake standby position is adjusted according to the cogging torque of the electric motor 6 in addition to the configuration of the first embodiment.
In this embodiment, the control device 5 has a cogging torque estimation function unit 11a that estimates a cogging torque value from an angle estimated by an angle estimation means including the angle sensor 9, and a braking state to a brake release state. A standby position adjusting function unit 11 is provided in which the motor angle at which the estimated cogging torque becomes substantially zero at the time of transition is set as the angle command value.

When the electric brake device is put into the standby state by the function of the brake standby function unit 16, the electric motor 6 rotates when an external force is applied. That is, when the brake standby state is entered with a rotational force in a predetermined direction due to the cogging torque, the electric motor 6 may be rotated by a predetermined amount due to the cogging torque. At that time, for example, according to the flow of FIG. 4, there is a possibility that the case where the brake standby function is executed (step S3) and the case where it is not (step S4) are repeated, which may result in unnecessary rocking.

Therefore, the cogging torque of the electric motor 6 is estimated, and the motor angle at which the cogging torque becomes zero is set in advance by the standby position adjusting function unit 11b at the standby position, thereby controlling the brake standby function unit 16. Is executed, the electric motor 6 is not rotated, and a predetermined brake standby state can be maintained. The cogging torque estimation may be performed by using an estimation LUT (look-up table) (not shown) or the like in advance based on the design or actual measurement, or is estimated in real time from the motor operation when the torque is set to zero. The method may be used.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and it is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 ... Friction brake mechanism 2 ... Linear actuator (friction material operating means)
3 ... Power supply device 4 ... Command means 5 ... Control device 6 ... Electric motor 8 ... Load sensor 9 ... Angle sensor (angle estimation means)
11a ... Cogging torque estimation function unit 11b ... Standby position adjustment function unit 12 ... Switching pattern determination function unit 13 ... Motor driver 14 ... Brake release request determination function unit 14a ... Counter 15 ... Release completion determination function unit 16 ... Brake standby function unit 21 ... Switch 21L ... L Arm switch circuit 21H ... H Arm switch circuit 22 ... Switch power supply 24 ... Charge 25H, 25L ... Transistor element 25Ha ... First input / output terminal 25Hb ... Second input / output terminal 25Hc ... Switching terminal 25La ... No. One input / output terminal 25Lb ... Second input / output terminal 25Lc ... Switching terminal 31 ... Brake rotor 32 ... Friction material

Claims (5)

The brake rotor, 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 by driving an electric motor, and the electric motor so as to follow a given brake command value. In an electric brake device including a control device for controlling the output of a motor and a DC power supply device for applying power to the electric motor.
The control device
A switch means for controlling the connection state between the coil end of the electric motor and the power supply device, and
A switch power supply that has a power storage function and functions as a power supply for switching at least a part of the switch means.
A charging means for accumulating electric power in the switch power supply in a predetermined switching pattern of the switch means,
A brake release request determination function unit that determines that an operation for requesting brake release has been performed when at least one of the brake force command value and its differential value becomes smaller than a predetermined value.
When it is determined that the operation requesting the brake release has been performed, the friction material operating means is driven to a predetermined brake release state, and the angle of the electric motor at this time and at least one of its differential values are used. The release completion judgment function unit that determines that the transition to the brake release state has been completed,
When it is determined that the transition to the release state is completed, at least the electric motor in a stationary state is not spontaneously driven, and the switch means can be stored in the switch power supply by the charging means. brake standby function unit to maintain the pattern, the capital possess,
The switch means is a switch circuit provided with a pair of L-arm switch and H-arm switch for each coil end of the electric motor.
The L-arm switch is connected to a first input / output terminal connected to the coil end of the electric motor, a second input / output terminal connected to the minus side of the power supply device, and the second input / output terminal. A switch circuit that controls the connection state between the negative side of the power supply device and the coil end of the electric motor by a transistor element having a switching terminal that connects both input / output terminals by inputting a positive potential. It is a department
The H-arm switch is connected to a first input / output terminal connected to the positive side of the power supply device, a second input / output terminal connected to the coil end of the electric motor, and the second input / output terminal. A switch circuit that controls the connection state between the positive side of the power supply device and the coil end of the electric motor by a transistor element having a switching terminal that connects both input / output terminals by inputting a positive potential. It is a department
The switch power supply is a capacitor connected to the second input / output terminal of the H arm switch as an electrical reference potential.
The charging means is a charging circuit that stores electric charges in a switch power supply composed of the capacitor when the L-arm switch is in a connected state.
In the brake standby function unit, all the L arm switches are always connected and all the H arm switches are always disconnected.
Electric braking device. In the electric brake device according to claim 1, the release completion determination function unit determines the deviation of the motor angle with respect to the motor angle target value at which a predetermined gap may be generated between the friction material and the brake rotor. An electric braking device that determines that the brake release is completed when the absolute value is equal to or less than a predetermined value and the absolute value of the motor angular speed is equal to or less than a predetermined value. In the electric brake device according to claim 1, the release completion determination function unit determines the deviation of the motor angle with respect to the motor angle target value at which a predetermined gap may be generated between the friction material and the brake rotor. An electric braking device including a counter that measures the duration of a state in which the absolute value is equal to or less than a predetermined value, and determines that the brake release is completed when the value of this counter exceeds the predetermined value. In the electric brake device according to any one of claims 1 to 3 , the brake standby function unit releases the brake standby function when the fluctuation of the motor angle becomes larger than a predetermined amount during execution. An electric brake device that drives the friction material to a predetermined brake release state. In the electric brake device according to any one of claims 1 to 3 , the control device has an angle estimating means for estimating an angle of the electric motor and a cogging torque for estimating a cogging torque from the estimated angle. An electric braking device having an estimation function unit and a standby position adjustment function unit whose angle command value is a motor angle at which the estimated cogging torque becomes substantially zero when shifting from a braking state to a braking release state.

Images