JP2019034679A - Electric brake device - Google Patents

Abstract

To provide an electric brake device capable of achieving both NVH, which is a generic term on noise, vibration, and ride quality, and control accuracy.SOLUTION: A control device 2 of an electric brake device 1 includes wheel motion estimation means 22, a control calculation function part 20 for switching a plurality of operation amounts based on a state amount of an electric motor 4, and a switching strength determination function part 21 for determining the steepness of switching required for switching the operation amounts in the control calculation function part 20 based on a brake force command value and the like. The switching strength determination function part 21 includes one or both of a function for determining whether or not smooth switching is to be executed for a switching condition in switching a plurality of the operation amounts, and a function for changing the steepness of a gradient in the smooth switching for a predetermined switching condition.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electric brake device, and relates to NVH, which is a general term for noise, vibration, and riding comfort, and a technique for achieving both control accuracy.

The following techniques have been proposed as an electric linear actuator or an electric brake device.
1. An electric brake actuator using an electric motor, a linear motion mechanism, and a speed reducer (Patent Document 1).
2. An electric actuator using a planetary roller mechanism and an electric motor (Patent Document 2).

JP-A-6-327190 JP 2006-194356 A

  In the electric brake device using the electric actuators of Patent Documents 1 and 2, when the actuator load is increased mainly due to the influence of mechanical friction or the like, and when the actuator load is reduced due to the reaction force, the motor torque and In many cases, the actuator has a hysteresis characteristic different from that of the actuator load. At this time, for example, when used for an application that requires a high-accuracy response such as an electric brake device, it may be difficult to control the actuator with high accuracy due to the influence of the hysteresis characteristics.

  As a countermeasure for improving the control accuracy with respect to this problem, there is a case where a variable structure control system that controls by switching a plurality of controllers according to a predetermined state of the actuator may be used. However, the sharper the controller is switched, the better the control accuracy is. On the other hand, NVH deteriorates due to chattering or the like, and the power consumption is likely to increase. The slower the controller is switched, the more the chattering is reduced. The effect of the variable structure is reduced, and the control accuracy is deteriorated.

  An object of the present invention is to provide an electric brake device that achieves both control accuracy and NVH, which is a generic name for noise, vibration, and riding comfort.

The electric brake device 1 according to the present invention includes a brake rotor 8, a friction material 9 that contacts the brake rotor 8 to generate a braking force, an electric motor 4, and an output of the electric motor 4 that presses the friction material 9. In an electric brake device comprising: a friction material operating means 6 for converting pressure, and a control device 2 for controlling the output of the electric motor 4 based on a brake force command value given from the command means 18;
The control device 2
Wheel motion estimation means 22 for estimating an angle in a rotational motion of the wheel WL synchronized with the brake rotor 8 and a predetermined differential value of this angle;
A control calculation function unit 20 that switches a plurality of different operation amounts based on a state quantity that is a physical quantity including at least one of the rotation angle of the electric motor 4 and a value synchronized with a predetermined differential value of the angle;
Based on one or both of the brake force command value from the command means 18 and the estimated value estimated by the wheel motion estimation means 22, the steepness of switching required for switching the operation amount in the control calculation function unit 20 A switching strength determination function unit 21 for determining
The switching intensity determination function unit 21 is a smoothing control that continuously switches from the current operation amount to the operation amount after switching for a predetermined switching condition in switching of a plurality of operation amounts in the control calculation function unit 20. It has one or both of a function for determining whether to perform switching and a function for changing the steepness of the gradient in the smooth switching with respect to a predetermined switching condition.
The determined switching condition is a switching condition arbitrarily determined by design or the like, and is determined by obtaining an appropriate switching condition by one or both of testing and simulation, for example.

  According to this configuration, the control calculation function unit 20 switches a plurality of operation amounts based on the state quantity. The switching strength determination function unit 21 determines the steepness of switching necessary for switching the operation amount in the control calculation function unit 20 based on one or both of the brake force command value and the estimated value of the wheel motion estimation means 22. . The switching strength determination function unit 21 determines whether or not to perform smooth switching for a predetermined switching condition, or changes the steepness of the gradient in the smooth switching. When the smooth switching is performed, the operation amount is continuously changed from one operation amount to another operation amount as the switching condition value changes. When the smooth switching is not performed, a discontinuous switching operation that changes from one operation amount to another operation amount is performed with respect to a predetermined threshold value in the switching condition.

When a variable structure control system that switches a plurality of controllers is applied, and only smooth switching is applied, one of the above must be compromised by the trade-off relationship between NVH and control accuracy, and either of the above compromises, That is, there may be a problem that the NVH deteriorates or the control accuracy decreases. At this time, the case where NVH becomes a problem may be different from the case where deterioration of responsiveness becomes a problem, depending on the conditions for braking.
Therefore, in this configuration, after applying a variable structure control system that switches a plurality of different operation amounts based on the state quantity such as the motor rotation angle, one or both of the following judgments a and b are executed. To do.
(Decision a): It is determined whether or not smooth switching is performed according to the brake force command value, the brake operation state, and the like.
(Judgment b): The steepness of smooth switching is made variable in accordance with the brake force command value, the brake operation state, etc. (this judgment b is based on the assumption that smooth switching is always performed).
By making at least one of the determinations, it is possible to achieve both NVH (Noise, Vibration, Harshness), which is a general term for noise, vibration, and riding comfort, and control accuracy.
For example, the smaller the brake force command value, etc., the smaller the pressure applied to the mechanical joint by the reaction force that presses the friction material against the brake rotor, so the effect on chattering will be greater and the amount of hysteresis that must be compensated for. It is small and the influence of the braking force on the braking distance is small. In such a case, smooth switching is performed to slow down switching of the variable structure control system. Conversely, if the brake force command value etc. is increased to some extent, the preload to the mechanical coupling part is relatively large, so the effect on chattering on the operating noise is relatively small, but the amount of hysteresis that must be compensated for increases. In addition, since the influence of the braking force on the braking distance increases, it is necessary to improve the brake control accuracy. In such a case, the switching of the variable structure control system is performed steeply, or a discontinuous switching operation is performed such that the predetermined operation amount is changed from one operation amount to another operation amount. Thus, by performing switching according to the situation, both NVH and control accuracy can be achieved.

Acceleration estimating means 28 for estimating the longitudinal acceleration of a vehicle on which the electric brake device 1 is mounted;
Vehicle speed estimation means 27 for estimating the vehicle speed of the vehicle based on either or both of the longitudinal acceleration estimated by the acceleration estimation means 28 and the estimated value estimated by the wheel motion estimation means 22; Prepared,
Based on the estimated value estimated by the wheel motion estimation means 22 and the vehicle body speed estimated by the vehicle body speed estimation means 27, the control device 2 estimates and estimates the degree of slip of the wheel WL with respect to the road surface. An anti-skid control function unit 19b that calculates a brake force command value without using the command means 18 so as to suppress the slip amount of the wheel WL when the slip degree exceeds a threshold;
The switching strength determination function unit 21 makes the gradient in the smooth switching when the control by the anti-skid control function unit 19b is executed steeper than that when the control by the anti-skid control function unit 19b is not executed. Has the function to change.
The threshold is determined by, for example, one or both of testing and simulation.

  According to this configuration, the gradient in the smooth switching when the control by the anti-skid control function unit 19b is executed is sharply changed as compared with the case where the control by the anti-skid control function unit 19b is not executed. That is, during anti-skid control, more precise braking force control is required than during normal braking operation. Therefore, the control accuracy can be improved by actively switching the variable structure control system.

  The switching strength determination function unit 21 may have a function of making the gradient in the smooth switching steep as the degree of change in the brake force command value based on the command means 18 becomes smaller. When the brake pedal is operated gently, the brake control accuracy can be increased by making the gradient in the smooth switching steep. Thereby, it is possible to improve the brake feeling by controlling the change in the braking force to accurately follow the brake operation.

The switching strength determination function unit 21 has a function of slowing the gradient in the smooth switching as the brake force command value becomes smaller under a condition that the brake force command value based on the command means 18 is smaller than a predetermined value. You may have.
The determined value is a value arbitrarily determined by design or the like, and is determined by obtaining an appropriate value by one or both of testing and simulation, for example.
In the case of a light brake operation, a relatively large operating noise of the electric brake device is likely to be generated, and if chattering occurs, the NVH is deteriorated. For this reason, when the braking force command value is smaller than a predetermined value, NVH can be improved by slowing the gradient in the smooth switching.

The switching strength determination function unit 21 has a function of slowing the gradient in the smooth switching as the braking force command value increases under a condition that the braking force command value based on the command means 18 is larger than a predetermined value. You may have.
The determined value is a value arbitrarily determined by design or the like, and is determined by obtaining an appropriate value by one or both of testing and simulation, for example.
When the braking force is increased to some extent, the deceleration becomes relatively high G, and the control accuracy hardly affects the feeling. In such a case, the gradient in the smooth switching can be made slow to improve NVH and reduce power consumption.

Vehicle body speed estimating means 27 for estimating the vehicle body speed of a vehicle on which the electric brake device 1 is mounted,
The switching strength determination function unit 21 may have a function of making the gradient in the smooth switching steep as the vehicle speed estimated by the vehicle speed estimation means 27 increases.
When the vehicle body speed is high, the road noise is large, so the influence of the operating sound of the electric brake device 1 on the NVH is relatively small, and the influence of the braking force on the braking distance is large. For this reason, the safety can be improved by improving the brake control accuracy by making the gradient in the smooth switching steep as the vehicle body speed increases.

The control device 2 has a brake force follow-up control function for controlling the amount of operation of the friction material 9 by the friction material operating means 6 so as to follow a brake force command value. A sliding mode control that calculates a switching function determined from the state quantity, derives a binary manipulated variable according to the sign of the switching function, and has a control target of substantially zero of the switching function;
The switching strength determination function unit 21 is a function for determining the steepness of the smooth switching according to a change in the value of the switching function when switching the binary operation amount based on the value of the switching function. May be.

The control device 2 controls the angular velocity estimating means 25 for estimating the angular velocity of the electric motor 4 and the brake force follow-up for controlling the operation amount of the friction material 9 by the friction material operating means 6 to follow the brake force command value. The brake force follow-up control function is a positive efficiency operation control calculator 33 that determines the operation amount of the electric motor 4 when the contact force between the friction material 9 and the brake rotor 8 increases. And two or more types of control calculators that determine the amount of operation of the electric motor 4 when the contact force is reduced, and two or more types of control calculators. A function of switching according to the angular velocity estimated by the means 25;
The switching strength determination function unit 21 determines a steepness of smooth switching associated with a change in the angular velocity when switching the operation amount of the two or more values based on the angular velocity estimated by the angular velocity estimating unit 25. It may be.

  The electric brake device according to 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 an output of the electric motor into a pressing force of the friction material. And a control device for controlling the output of the electric motor based on a brake force command value given from the command means, wherein the control device rotates a wheel synchronized with the brake rotor. A state quantity which is a physical quantity including at least one of an angle in motion and a wheel motion estimation means for estimating a predetermined differential value of the angle, and an angle of rotation of the electric motor and a value synchronized with the predetermined differential value of the angle Based on the control calculation function unit for switching a plurality of different operation amounts, the brake force command value from the command means and the wheel motion estimation A switching strength determination function unit that determines steepness of switching necessary for switching the operation amount in the control calculation function unit based on one or both of the estimated values estimated in the stage, and the switching strength determination Whether the function unit performs smooth switching, which is control for continuously switching from the current operation amount to the operation amount after switching in accordance with a predetermined switching condition in switching of a plurality of operation amounts in the control calculation function unit. And a function of changing the steepness of the gradient in the smooth switching with respect to a predetermined switching condition. For this reason, it is possible to achieve both NVH, which is a generic name for noise, vibration, and riding comfort, and control accuracy.

It is a figure showing roughly the electric brake equipment concerning the embodiment of this invention. It is a block diagram of a control system of the electric brake device. It is a figure which shows the example which switches the operation amount in the same electric brake device. In the same electric brake device, it is a flowchart showing an example of changing the gradient of smooth switching depending on whether or not the anti-skid control. It is a block diagram which shows the example of the control structure which switches the same operation amount. It is a block diagram of the control system of the electric brake device which concerns on other embodiment of this invention. In the same electric brake device, it is a figure showing an example of adjusting the linear gradient θ _SW according to the degree of change of the braking force or the braking force command value. It is a block diagram of the control system of the electric brake device which concerns on further another embodiment of this invention. In the same electric brake device, it is a figure which shows the example which adjusts linear gradient (theta) _SW according to the estimated vehicle body speed. FIG. 12 is a block diagram illustrating another example of a control configuration for switching an operation amount in an electric brake device according to still another embodiment of the present invention.

An electric brake device according to an embodiment of the present invention will be described with reference to FIGS. This electric brake device is mounted on a vehicle, for example.
As shown in FIG. 1, the electric brake device 1 includes an electric linear actuator DA and a friction brake BR. First, the structure 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 FIGS. 1 and 2, the electric linear actuator DA includes an actuator body AH and a control device 2 described later. The actuator body AH includes an electric motor 4, a speed reduction mechanism 5, a linear motion mechanism 6 that is a friction material operating means, a parking brake mechanism 7, an angle sensor Sa, and a load sensor Sb.

  The electric motor 4 is preferably composed of a permanent magnet type synchronous motor, which is suitable for space saving and high torque. For example, a DC motor using a brush, a reluctance motor not using a permanent magnet, or an induction motor is applied. You can also.

  The friction brake BR includes a brake rotor 8 that rotates in conjunction with the vehicle wheel WL, and a friction material 9 that contacts the brake rotor 8 and generates a braking force. The friction material 9 is disposed in the vicinity of the brake rotor. It is possible to use a mechanism in which the friction material 9 is operated by the actuator main body AH and pressed against the brake rotor 8 to generate a braking force by a 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.

  The reduction mechanism 5 is a mechanism that reduces 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 speed reduction mechanism 5 decelerates the rotation of the primary gear 12 attached to the rotor shaft 4 a of the electric motor 4 by the intermediate gear 13 and transmits it 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 for converting the rotational motion output from the speed reduction mechanism 5 into a linear motion of the linear motion portion 14 by a feed screw mechanism and bringing the friction material 9 into contact with and separated from the brake rotor 8. The linear motion part 14 is supported so as to be free of rotation and movable in the axial direction indicated by the arrow A1. A friction material 9 is provided on 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 speed reduction mechanism 5, the rotational motion is converted into a linear motion, which is converted into a pressing force of the friction material 9 to generate a braking force. . In the state where the electric brake device 1 is mounted on the vehicle, the vehicle width direction outer side of the vehicle is referred to as an outboard side, and the vehicle width direction center side of the vehicle is referred to as an inboard side.

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

  As shown in FIG. 2, the angle sensor Sa estimates the rotation angle of the electric motor 4. As the angle sensor Sa, for example, a resolver or a magnetic encoder is preferably used because of high performance 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 to be described later, angle sensorless estimation that estimates the motor angle from the relationship between the voltage and current of the electric motor 4 can be used.

  The load sensor Sb is a brake force estimation unit that estimates a brake force, and is used when the brake force is controlled. As the load sensor Sb, for example, a magnetic sensor, a strain sensor, a pressure sensor, or the like that detects a displacement or deformation of a predetermined portion where the load of the linear motion mechanism 6 acts can be used. Instead of using the load sensor Sb, the control device 2 may perform the load sensorless estimation from the motor angle and the electric brake device rigidity, the motor current and the efficiency of the electric linear actuator DA, or the like. Various sensors such as a thermistor may be separately provided according to requirements.

  The vehicle is provided with a wheel speed sensor Sc that detects the rotational speed (wheel speed) of each wheel WL. As the wheel speed sensor Sc, for example, a wheel speed sensor that outputs a predetermined number of pulses during one rotation of the wheel WL is preferable because an inexpensive system can be configured. Alternatively, a sensor that detects an angle, such as the angle sensor Sa that detects the rotation angle of the electric motor 4, can also be used.

<About the control device 2>
FIG. 2 is a block diagram of a control system of the electric brake device 1.
For example, a control device 2 and an actuator main body AH corresponding to each wheel WL are provided. Each control device 2 controls a corresponding electric motor 4. Each control device 2 is connected to a power supply device 3 and upper control means (not shown) of each control device 2. The power supply device 3 supplies power to the electric motor 4 and the motor driver 17 of the control device 2. As the upper control means, for example, an electric control unit for controlling the entire vehicle is applied. The host control means has an integrated control function of each control device 2. The upper control means outputs a braking force command value to each control device 2 from the command means 18 such as a brake pedal, for example.

  Each control device 2 includes various control function units that perform control calculations and a motor driver 17. The various control function units include a brake command value generation function unit 19, a control calculation function unit 20, a switching strength determination function unit 21, wheel motion estimation means 22, and a wheel speed estimation function unit 23. The wheel motion estimation means 22 includes a load estimation function unit 24 and a motor motion estimation function unit 25. The load estimation function unit 24 has a function of estimating the axial load (estimated brake force) of the linear motion mechanism 6 from the output of the load sensor Sb and the like. When performing the load sensorless estimation, the load estimation function unit 24 may estimate the axial load of the linear motion mechanism 6 using information such as a motor angle or a motor current.

  The motor motion estimation function unit 25 has a function of estimating the rotational motion state of the electric motor 4 from the output of the angle sensor Sa and the like. For example, when a sensor such as a resolver or a magnetic encoder that detects a predetermined angle region as one cycle is used as the angle sensor Sa, the motor motion estimation function unit 25 determines the rotor of the electric motor 4 from the output of the angle sensor Sa. The phase may be estimated, and the integrated value of the fluctuation amount in the rotor phase may be estimated as the total rotation angle (position). Further, the differential equivalent value of the phase or position may be estimated as the angular velocity. Alternatively, for example, when the angle sensorless estimation described above is performed, the motor motion estimation function unit 25 may estimate the phase or angular velocity of the rotor from the motor voltage and the motor current.

  The wheel speed estimation function unit 23 outputs, for example, within a time period in which one pulse is output or within a predetermined time from the output of the wheel speed sensor Sc that outputs a predetermined number of pulses during one rotation of the wheel WL. A function of counting the number of pulses and estimating the wheel speed based on a predetermined conversion formula may be used. Any of the above methods may be used, and the wheel speed estimation function unit 23 may be, for example, an estimation method that switches the above method using a predetermined estimated angular velocity as a threshold value. In addition, when using a sensor that detects an angle, such as a motor angle sensor, for example, the wheel speed estimation function unit 23 can also estimate the angular speed based on the differentiation of the angle or the like.

  The brake command value generation function unit 19 includes a service brake command calculation unit 19a and an anti-skid command calculation unit 19b. The service brake command calculation unit 19a estimates the brake force required for a normal service brake based on the command means 18 such as a brake pedal, for example, and sets it as a brake force command value. The brake force command value is given to the brake control function unit 26 of the control calculation function unit 20.

  The anti-skid command calculation unit 19b, for example, based on the vehicle speed estimated by the vehicle speed estimation unit 27 and the wheel speed (estimated value) estimated by the wheel speed estimation function unit 23, the degree of slip of the wheels WL with respect to the road surface ( Anti-skid by calculating a braking force command value without using the command means 18 so as to suppress the slip amount of the wheel WL when the estimated slip degree exceeds a threshold value. Execute control. Information regarding whether the service brake command calculation unit 19a is performing calculation or the anti-skid command calculation unit 19b is performing calculation is provided to the switching strength determination function unit 21.

  The vehicle body speed estimation means 27 may estimate the vehicle body speed from, for example, the longitudinal acceleration of the vehicle estimated by the acceleration estimation means 28, the estimated wheel speed of each wheel generally provided, and the like. The vehicle body speed estimation means 27 may be a means that uses or uses GPS as another element not shown. Further, as an element not shown in the figure, for example, a brake control means based on vehicle motion such as a skid prevention control can be separately provided in the control device 2.

  The control arithmetic function unit 20 has a function of switching a plurality of different operation amounts based on a state quantity that is a physical quantity including any one of a motor angle and a value synchronized with a predetermined differential value of the motor angle. The control calculation function unit 20 includes a brake control function unit 26 and an operation amount switching function unit 29. The brake control function unit 26 controls the electric motor 4 so that the estimated brake force follows the brake force command value requested by the command means 18.

  The control calculation by the brake control function unit 26 may use, for example, feedback control that directly uses the brake force command value and the estimated brake force. The control calculation is performed by converting the brake force into another physical quantity such as an angle. Also good. The feedback control may be, for example, an arithmetic structure in which a plurality of minor feedback loops are provided so that a motor current control loop is provided in a brake force control loop, or a motor operation amount is calculated in a single feedback loop. Also good. In addition, feed forward control or the like can be used, or feed forward control or the like can be used in combination as appropriate.

The brake control function unit 26 switches the plurality of operation amounts based on the operation amount calculation units 26 ₁ , 26 ₂ ,... That calculate a plurality of operation amounts with respect to the predetermined state amount. And a switching control unit 30 that calculates a switching condition serving as a condition for this.

  The operation amount switching function unit 29 has a function of switching and outputting one of the plurality of operation amounts as an electric brake operation amount based on the plurality of operation amounts calculated by the brake control function unit 26 and the switching control signal. . At this time, the operation amount switching function unit 29 discontinuously changes the operation amount from “1” to the operation amount “2”, for example, with respect to the predetermined threshold in the switching condition in the switching of the plurality of operation amounts. A function for performing a switching operation and a continuous smoothing that is continuously changed from the operation amount “1” to the operation amount “2” with the transition of the value of the switching condition within a predetermined range of the switching condition. And a function of performing a switching operation.

  In this example, the switching strength determination function unit 21 determines the steepness of switching necessary for switching the operation amount in the operation amount switching function unit 29 based on whether or not the anti-skid control is performed, and the operation amount switching function The switching process in the unit 29 is adjusted. In general, the brake control accuracy at the time of anti-skid control is extremely important, whereas the importance of NVH at the time of anti-skid control is often extremely low.

For this reason, the switching strength determination function unit 21 can perform switching processing with steepness that places the highest importance on control accuracy during anti-skid control.
The determination of the steepness of switching in the switching strength determination function unit 21 is mainly based on the necessity of the brake force control accuracy and the viewpoint of NVH, and the switching processing becomes sharper and NVH is more important as the control accuracy is more important. The switching process can be made slower.

  For example, the motor driver 17 constitutes a half bridge circuit using a switching element such as a field effect transistor (abbreviated as FET), and performs PWM control for determining a motor applied voltage with a predetermined duty ratio. It is inexpensive and has high performance. Or the motor driver 17 can also be set as the structure which provides a transformer circuit etc. and performs PAM control, for example.

  In addition, an unillustrated current sensor or the like can be provided as needed. Each functional block in FIG. 2 is provided for convenience in explaining the function, and may be integrated or divided as necessary, or a predetermined function may be omitted as appropriate.

<Example of operation amount switching operation>
FIG. 3 is a diagram illustrating an example in which the operation amount is switched by the electric brake device. Hereinafter, description will be given with reference to FIG. In FIG. 3A, the control calculation function unit 20 (FIG. 2) converts the binary operation amount (operation amount 1, operation amount 2) through a linear smoothing function Fc in the vicinity of the switching threshold value under a predetermined switching condition. An example of switching is shown. 3 is, for example, a state quantity such as an angular velocity of the electric motor 4, dynamics obtained by converting the state quantity into a predetermined eigenvalue, and the like. The linear gradient θ _SW in FIG. 3A can be used as a parameter representing the steepness of switching. The switching strength determination function unit 21 (FIG. 2) can change the linear gradient θ _SW with respect to a predetermined switching condition.

FIG. 3B shows an example in which the binary operation amount (operation amount 1, operation amount 2) is switched through a curved smooth function Fc, in contrast to the example of FIG. The curved smooth function Fc may be defined by using, for example, a trigonometric function. For example, the width xsw from the start to the end of switching can be used as a parameter representing the steepness of switching. Alternatively, as shown in FIG. 3A, a value corresponding to the gradient θ _SW in the vicinity of the switching threshold may be used as a parameter representing the steepness of switching. Conversely, in the smoothing function Fc of FIG. 3A, a value corresponding to the width xsw from the start to the end of switching may be used as a parameter representing the steepness of switching. The switching strength determination function unit 21 (FIG. 2) can change the width xsw with respect to a predetermined switching condition.

FIG. 4 is a flowchart showing an example of changing the gradient θ _SW of the smoothing function depending on whether or not the anti-skid control is being performed in this electric brake device. After the start of this process, the switching strength determination function unit 21 (FIG. 2) determines whether or not the anti-skid control is being executed based on the brake control mode information from the brake command value generation function unit 19 (step S1). When it is determined that the anti-skid control is being performed (step S1: yes), the switching strength determination function unit 21 (FIG. 2) increases the gradient θ _{SW of the} smoothing function more than when the anti-skid control is not being performed (step S2). ). Thereafter, this process is terminated. If it is determined that the anti-skid control is not being performed (step S1: no), the switching strength determination function unit 21 (FIG. 2) makes the gradient θ _SW smaller than that during the anti-skid control (step S3). Thereafter, this process is terminated.

<Example of control configuration for switching the operation amount>
FIG. 5 is a block diagram illustrating a configuration example of a control system for switching the operation amount. In this configuration example, as a variable switching structure system, a switching function having a predetermined dynamics is calculated from a state quantity composed of a motor angle, etc., a nonlinear input is calculated according to the switching function, and an actual response is converted into a dynamics of the switching function. The example which applies sliding mode control which restrains is shown.

  The state estimator corresponding to the wheel motion estimator 22 can be constituted by, for example, a linear state observer or a VSS observer. The state quantity x obtained by this state estimator is, for example, a state quantity that forms an equation of motion such as a motor angle, an angular velocity (a first derivative value of the motor angle), an angular acceleration (a second derivative value of the motor angle), and the like. be able to. Moreover, in order to achieve the follow-up control of the braking force, a deviation between a predetermined command value and a state quantity, or an integral (integrated) value of the deviation can be included.

  In the switching function calculator 31 in the control calculation function unit 20, the switching function σ is calculated as σ = Sx having a desired response dynamics with respect to the state quantity x given from the state estimator 22. The S is a coefficient for the switching function σ to have a desired dynamic with respect to the state quantity x, and can be obtained, for example, by pole arrangement or an optimal regulator.

The nonlinear input calculator 32 in the control calculation function unit 20 (brake force follow-up control function unit) is a function mainly for the purpose of compensating for disturbance or model error, and has a predetermined operation amount + u according to the sign of the switching function σ. , -U are switched to generate a control input that constrains the state quantity to σ≈0. At this time, the non-linear input computing unit 32 becomes more restrictive to the state quantity σ = 0 as the switching strength determination function unit 21 makes the switching sharper, and on the other hand, chattering occurs. In other words, the steeper switching of the non-linear input is advantageous for control accuracy, and is disadvantageous for NVH and power consumption.
The switching strength determination function unit 21 determines the steepness of switching of the nonlinear control input based on the determined switching condition.

<Effect>
According to the electric brake device 1 described above, the switching strength determination function unit 21 determines the steepness of switching necessary for switching the operation amount in the operation amount switching function unit 29 based on whether or not the anti-skid control is performed. Then, the switching process in the operation amount switching function unit 29 is adjusted. In general, the brake control accuracy at the time of anti-skid control is extremely important, whereas the importance of NVH at the time of anti-skid control is often extremely low. For this reason, the switching strength determination function unit 21 can perform switching processing with steepness that places the highest importance on control accuracy during anti-skid control. Therefore, both NVH and control accuracy can be achieved.

<About other embodiments>
In the following description, the same reference numerals are given to portions corresponding to the matters described in advance in the respective embodiments, and overlapping descriptions are omitted. When only a part of the configuration is described, the other parts of the configuration are the same as those described in advance unless otherwise specified. The same effect is obtained from the same configuration. Not only the combination of the parts specifically described in each embodiment, but also the embodiments can be partially combined as long as the combination does not hinder.

  As shown in FIG. 6, the switching strength determination function unit 21 shows an example of determining the switching strength based on one or both of the brake force command value and the estimated braking force. In general, in the case of a light brake operation, a relatively large operating noise of the electric brake device 1 is likely to be generated, and when chattering occurs, NVH is deteriorated. Conversely, as the braking force increases, the NVH is less likely to deteriorate due to the pressure applied to the mechanical coupling portion of the actuator body AH. For this reason, the switching strength determination function unit 21 slows down the switching as either one or both of the braking force command value and the estimated braking force becomes smaller, and either or both of the braking force command value and the estimated braking force become larger. The switching can be made steeper (see the left half of FIG. 7A).

Further, when the braking force increases, the deceleration becomes relatively high G, and the control accuracy hardly affects the feeling. For this reason, the switching strength determination function unit 21 may perform a process of slowing down the switching as the braking force command value increases under the condition that the braking force command value is larger than the predetermined value (FIG. 7A, right half). Part).
FIG. 7A shows an example of adjusting the steepness of the smoothing function according to the braking force shown in FIG. As the brake force on the horizontal axis in FIG. 7A, a brake force command value may be used, or an actual estimated brake force may be used.

  FIG. 7B shows an example of adjusting the steepness of the smoothing function in accordance with the degree of change in the braking force command value shown in FIG. The gentler the degree of change in brake force command value (differential value, etc.), the more sensitive the vehicle operator is to the degree of change in brake force. Conversely, the steeper degree of change in the brake force command value may make the driver less sensitive to the degree of change in the brake force.

Therefore, as shown in FIG. 6 and FIG. 7B, the switching strength determination function unit 21 makes the gradient θ _{SW of the} smoothing function steeper as the degree of change in the brake force command value decreases, and changes in the brake force command value. The gradient θ _SW may be made slower as the degree increases.
When the brake pedal is operated gently, the brake control accuracy can be increased by making the gradient in the smooth function steep. Thereby, it is possible to improve the brake feeling by controlling the change in the braking force to accurately follow the brake operation.

  As shown in FIGS. 8 and 9, the switching strength determination function unit 21 may make the gradient in the smooth function steeper as the vehicle speed estimated by the vehicle speed estimation means 27 increases. In general, when the vehicle body speed is high, the brake operation sound is unlikely to affect NVH due to road noise or the like. Conversely, when the vehicle body speed is low (particularly when the vehicle is stopped), the influence of the brake operating sound is relatively large. Further, the influence of the braking force on the braking distance is relatively large as the vehicle body speed is high, and is relatively small as the vehicle body speed is low. Therefore, the switching strength determination function unit 21 executes a process of making the switching steeper as the vehicle speed estimated by the vehicle speed estimation means 27 increases and making the switching slower as the vehicle speed decreases. This is preferable because both safety and NVH can be achieved.

Any of the control systems of FIGS. 2, 6, and 8 may be used, or may be used in combination as appropriate.
7 and FIG. 9, an example using the linear gradient θ _SW of FIG. 3A is shown. However, the width xsw of FIG. 3B may be used. A variable that defines the steepness at which the operation amount is switched can be used as appropriate.

  In the control configuration for switching the operation amount shown in FIG. 10, in the actuator body AH, the normal efficiency operation control calculator 33 in the pressure increasing state, the reverse efficiency operation control calculator 34 in the pressure reducing state, and the hysteresis intermediate control calculator in the hysteresis intermediate state. An example of switching to 35 is shown. The increased pressure state is synonymous with a state where the contact force between the friction material 9 (FIG. 1) and the brake rotor 8 (FIG. 1) increases, and the reduced pressure state is synonymous with a state where the contact force decreases. It is.

  In general, in an electric linear actuator that is used in an electric brake device, even when the thrust is the same, the load when the pressure is increased by the rotational motion from the electric motor (positive efficiency) and the load when the pressure is reduced (reverse efficiency) Is different. In other words, it can be considered that the equivalent spring rate is different between the normal efficiency operation and the reverse efficiency operation. In particular, in an operation in the middle of hysteresis, the actuator main body does not operate in response to a change in motor torque (motor current), so that the control is disabled.

  Therefore, as shown in FIG. 10, the control calculation function unit 20 which is a brake force follow-up control function unit uses the normal efficiency operation control calculator 33 using the parameters in the normal efficiency operation and the parameters in the reverse efficiency operation. The reverse efficiency operation control computing unit 34 and the hysteresis intermediate control computing unit 35 applied in the case of being in the hysteresis are provided. For example, a linear controller such as a deviation compensator or a state feedback unit is preferably used as each of the control calculators because the design man-hours and calculation load can be reduced. In particular, the hysteresis intermediate control calculator 35 may be mounted as a controller that controls the motor current to a predetermined torque when the actuator main body AH is set as an uncontrollable control state in which the actuator body AH does not operate.

  The operation amount switching function unit 29 in the control calculation function unit 20 switches the controller based on whether the actuator body AH is in a pressure increase, pressure reduction, or hysteresis intermediate state. In other words, the operation amount switching function unit 29 applies the operation amount of the positive efficiency operation control computing unit 33 when the polarity of the angular velocity given from the state estimator 22 is in the pressure increasing direction (positive) as the switching condition, and the switching is performed. As a condition, when the polarity of the angular velocity is in the pressure reduction direction (negative), the operation amount of the reverse efficiency operation control calculator 34 is applied. The manipulated variable switching function unit 29 applies the hysteresis intermediate control calculator 35 when the polarity of the angular velocity is approximately zero as the switching condition.

  At this time, the switching strength determination function unit 21 can use the motor angular velocity as a switching function and appropriately set the smooth switching gradient in the vicinity of the threshold angular velocity zero. The hysteresis intermediate control calculation unit 35 may be omitted in a transient response state in the middle of following a predetermined brake force, and may be applied only when a follow-up state is achieved with respect to a substantially constant brake force command value.

The switching strength determination function unit 21 is in the vicinity of the switching threshold when changing the steepness of smooth switching for a predetermined switching condition in switching of a plurality of operation amounts in the control calculation function unit 20 shown in FIG. It may be configured to include the case where the gradient θ _{SW of the switch} is 90 degrees. When the gradient θ _SW is 90 degrees, smooth switching is not performed. Alternatively, the switching strength determination function unit 21 changes the steepness of smooth switching with respect to a predetermined switching condition in switching of a plurality of operation amounts in the control calculation function unit 20 shown in FIG. The smoothing function Fc may include a case where the width xsw from the start to the end of the switching is zero. When the width xsw is zero, smooth switching is not performed.

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 using an inclination of a ball ramp, and the like can be used.
The load sensor Sb may be other external sensors such as a sensor for detecting the wheel torque of a wheel on which a brake is mounted or a longitudinal force of a vehicle on which an electric brake device is mounted instead of the above-described sensor or the like.

  As mentioned above, although the form for implementing this invention based on embodiment was demonstrated, embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 ... Electric brake device 2 ... Control apparatus 4 ... Electric motor 6 ... Linear motion mechanism (friction material operation means)
8 ... Brake rotor 9 ... Friction material 18 ... Command means 19b ... Anti-skid command calculation unit (anti-skid control function unit)
DESCRIPTION OF SYMBOLS 20 ... Control arithmetic function part 21 ... Switching intensity | strength judgment function part 22 ... Wheel motion estimation means 25 ... Motor motion estimation function part (angular velocity estimation means)
27 ... Vehicle speed estimation means 28 ... Acceleration estimation means 33 ... Normal efficiency operation control calculator 34 ... Reverse efficiency operation control calculator

Claims (8)

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 command means A control device for controlling the output of the electric motor based on the braking force command value,
The control device includes:
Wheel motion estimation means for estimating an angle in a rotational motion of a wheel synchronized with the brake rotor and a predetermined differential value of this angle;
A control calculation function unit that switches a plurality of different operation amounts based on a state quantity that is a physical quantity including at least one of an angle of rotation of the electric motor and a value synchronized with a predetermined differential value of the angle;
Based on one or both of the brake force command value from the command unit and the estimated value estimated by the wheel motion estimation unit, the steepness of switching necessary for switching the operation amount in the control calculation function unit is determined. A switching strength determination function unit,
The switching strength determination function unit performs smooth switching, which is a control for continuously switching from the current operation amount to the operation amount after switching with respect to a predetermined switching condition in switching of a plurality of operation amounts in the control calculation function unit. An electric brake device having one or both of a function of determining whether or not to perform and a function of changing a steepness of a gradient in the smooth switching with respect to a predetermined switching condition. The electric brake device according to claim 1, wherein an acceleration estimating means for estimating a longitudinal acceleration of a vehicle equipped with the electric brake device;
Vehicle speed estimation means for estimating the vehicle speed of the vehicle based on one or both of the longitudinal acceleration estimated by the acceleration estimation means and the estimated value estimated by the wheel motion estimation means, and
The control device estimates the degree of slippage of the wheels with respect to the road surface based on the estimated value estimated by the wheel motion estimation unit and the vehicle body speed estimated by the vehicle body speed estimation unit, and the estimated degree of slipping is calculated. An anti-skid control function unit that calculates a braking force command value regardless of the command means so as to suppress the slip amount of the wheel when a threshold value is exceeded,
The switching strength determination function unit has a function of changing the gradient in the smooth switching when the control by the anti-skid control function unit is executed sharply compared to the case where the control by the anti-skid control function unit is not executed. Electric brake device having   3. The electric brake device according to claim 1, wherein the switching strength determination function unit makes the gradient in the smooth switching steep as the degree of change in the brake force command value based on the command unit decreases. Electric brake device having   The electric brake device according to any one of claims 1 to 3, wherein the switching strength determination function unit is configured to perform the braking force under a condition that a braking force command value based on the commanding unit is smaller than a predetermined value. An electric brake device having a function of slowing the gradient in the smooth switching as the command value becomes smaller.   5. The electric brake device according to claim 1, wherein the switching strength determination function unit is configured to apply the brake force under a condition that a brake force command value based on the command means is larger than a predetermined value. An electric brake device having a function of slowing the gradient in the smooth switching as the command value increases. The electric brake device according to any one of claims 1 to 5, further comprising vehicle body speed estimating means for estimating a vehicle body speed of a vehicle on which the electric brake device is mounted.
The switching strength determination function unit is an electric brake device having a function of making the gradient in the smooth switching steep as the vehicle speed estimated by the vehicle speed estimation means increases. The electric brake device according to any one of claims 1 to 6, wherein the control device controls the operation amount of the friction material by the friction material operation means so as to follow a brake force command value. This brake force tracking control function calculates a switching function determined from the state quantity, derives a binary manipulated variable according to the sign of the switching function, Sliding mode control with a control target of approximately zero,
The switching strength determination function unit is a function that determines the steepness of the smooth switching according to a change in the value of the switching function when switching the binary operation amount based on the value of the switching function. Brake device. 8. The electric brake device according to claim 1, wherein the control device is configured to estimate an angular velocity of the electric motor and an operation amount of the friction material by the friction material operation device. A brake force tracking control function for controlling the brake motor to follow the brake force command value, and the brake force tracking control function of the electric motor when the contact force between the friction material and the brake rotor increases. Binary value by two or more types of control arithmetic units including a normal efficiency operation control arithmetic unit that determines an operation amount and a reverse efficiency operation control arithmetic unit that determines an operation amount of the electric motor when the contact force decreases. A function of switching the above operation amount in accordance with the angular velocity estimated by the angular velocity estimating means,
The switching strength determination function unit is a function for determining the steepness of smooth switching associated with a change in the angular velocity when switching the operation amount of the two or more values based on the angular velocity estimated by the angular velocity estimating means. Electric brake device.

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