WO2019039397A1

WO2019039397A1 - Electric brake device

Info

Publication number: WO2019039397A1
Application number: PCT/JP2018/030505
Authority: WO
Inventors: 唯増田
Original assignee: Ntn株式会社
Priority date: 2017-08-21
Filing date: 2018-08-17
Publication date: 2019-02-28
Also published as: JP6906398B2; JP2019034679A

Abstract

Provided is an electric brake device which achieves both NVH, a collective term referring to noise, vibration, and harshness, and control accuracy. A control device (2) of the electric brake device 1 is provided with: a wheel motion estimation means (22); a control calculation function unit (20) which switches an operation amount between a plurality of mutually different operation amounts, in accordance with a state amount of an electric motor (4), and an switching intensity determination function unit (21) which, on the basis of a brake force command value and the like, determines the sharpness of switching required for switching the operation amount in the control calculation function unit (20). The switching intensity determination function unit (21) includes the function for determining whether, during switching of the operation amount, to perform smooth switching with respect to a determined switching parameter, and/or the function for modifying the gradient indicating the sharpness of smooth switching with respect to the determined switching parameter.

Description

Electric brake device

Related application

This application claims the priority of Japanese Patent Application No. 2017-158448 filed on Aug. 21, 2017, which is incorporated by reference in its entirety.

The present invention relates to an electric brake device, and relates to a technology for achieving both control accuracy and NVH (Noise, Vibration, Harshness), which is a generic term for noise, vibration and ride comfort.

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

Japanese Patent Application Laid-Open No. 6-327190 JP, 2006-194356, A

In the electric brake device using the electric actuator of

Patent Documents

1 and 2, the motor torque and the motor torque are respectively increased when increasing the actuator load and reducing the actuator load due to the influence of mechanical friction and the like. In many cases, the characteristics with the actuator load have different hysteresis characteristics. At this time, for example, when used for an application requiring a high accuracy response such as an electric brake device, high accuracy actuator control may be difficult due to the influence of the hysteresis characteristic.

As a measure for improving the control accuracy with respect to this problem, a variable structure control system which switches and controls a plurality of controllers in accordance with a predetermined state of the actuator may be used. However, although the control accuracy is improved as the switching of the controller is performed more rapidly, the deterioration of the NVH or the increase of the power consumption is more likely to occur due to chattering or the like, and the chattering is reduced as the switching of the controller is performed more slowly. The trade-off is a problem in that 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 term for noise, vibration and ride comfort.

Hereinafter, in order to facilitate understanding, for convenience, reference will be made to the reference numerals of the embodiments.

The electric brake device 1 according to the present invention comprises a brake rotor 8, a friction member 9 which generates a braking force in contact with the brake rotor 8, an electric motor 4, and an output of the electric motor 4 In an electric brake apparatus comprising: friction material operating means 6 for converting into pressure; and a control device 2 for controlling the output of the electric motor 4 based on the braking force command value given from the command means 18
The control device 2 is
Wheel motion estimating means 22 for estimating an angle in rotational motion of the wheel WL synchronized with the brake rotor 8 and a predetermined order differential value of the angle;
A control operation function unit that switches the operation amount among a plurality of operation amounts different from each other according to a state amount that is a physical amount including at least one of an angle of rotation of the electric motor 4 and a value corresponding to a predetermined differential value of this angle. 20 and
Steepness of switching necessary for switching of the operation amount in the control calculation function unit 20 based on one or both of the braking force command value from the command means 18 and the estimated value estimated by the wheel motion estimation means 22 And a switching strength determination function unit 21 for determining
The switching strength determination function unit 21 performs smooth switching, which is control for continuously switching from a current operation amount to a post-switching operation amount with respect to a predetermined switching parameter when switching the operation amount in the control calculation function unit 20. And a function of changing the slope indicating the steepness of the smooth switching with respect to a predetermined switching parameter.

According to this configuration, the control calculation function unit 20 switches the operation amount among the plurality of operation amounts in accordance with the state amount. 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 either 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 the smooth switching on the determined switching parameter, or changes the gradient indicating the steepness of the smooth switching. When the smooth switching is performed, the operation amount is continuously changed from one operation amount to another operation amount along with the transition of the value of the switching parameter. When the smooth switching is not performed, a discontinuous switching operation is performed such that one operation amount is replaced with another operation amount with respect to a predetermined threshold value in the switching parameter.

If a variable structure control system for switching a plurality of controllers is applied and only a smooth switching is applied, either of the above must be compromised due to the trade-off relationship between NVH and control accuracy That is, the deterioration of the NVH or the reduction of the control accuracy may be a problem. At this time, depending on the conditions under which braking is performed, the case where NVH becomes a problem may differ from the case where a decrease in responsiveness becomes a problem.

So, in this composition, after applying the variable structure control system which changes a plurality of mutually different operation quantity based on the above-mentioned state quantities, such as a motor rotation angle, either one or both of the following judgments a and b are performed Do.
(Determination a): It is determined whether or not smooth switching is to be performed according to the braking force command value, the braking operation state, and the like.
(Decision b): The slope of the smooth switching is variable according to the braking force command value, the brake operation state, etc. (In this judgment b, smooth switching is always performed).

By performing at least one of the determinations, it is possible to balance control accuracy with NVH, which is a generic term for noise, vibration, and ride comfort. For example, the smaller the braking force command value or the like, the smaller the pressure applied to the mechanical joint by the reaction force that presses the friction material against the brake rotor, so the chattering has a greater effect on the operation noise, and the hysteresis amount must be compensated 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 the switching of the variable structure control system. Conversely, if the braking force command value or the like is increased to a certain extent, the preload on the mechanical joint is relatively large, while the influence of chattering on the operation noise is relatively small, but the hysteresis amount to be compensated is increased. In addition, since the influence of the braking force on the braking distance becomes large, it is necessary to improve the brake control accuracy. In such a case, switching of the variable structure control system is made steep, or discontinuous switching operation is performed such that one operation amount is replaced with another operation amount with respect to a predetermined threshold value in the switching parameter. By performing switching according to the situation as described above, it is possible to achieve both NVH and control accuracy.

Acceleration estimation means 28 for estimating longitudinal acceleration of a vehicle equipped with the electric brake device 1;
A vehicle speed estimation means 27 for estimating the vehicle body speed of the vehicle based on one 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; Equipped
The control device 2 further estimates the degree of slippage of the wheel WL with respect to the road surface based on the estimated value estimated by the wheel motion estimation means 22 and the vehicle speed estimated by the vehicle speed estimation means 27. The anti-skid control function unit 19b calculates a braking force command value regardless of the command unit 18 so as to suppress the slip amount of the wheel WL when the calculated slippage degree exceeds a threshold value,
The switching strength judgment function unit 21 makes the gradient in the smooth switching when the control by the antiskid control function unit 19b is executed sharper than that when the control by the antiskid control function unit 19b is not executed. It may have a function to The threshold is determined by, for example, one or both of a test and a simulation.

According to this configuration, the gradient in the smooth switching when the control by the anti-skid control function unit 19 b is performed is made steep as compared with the case where the control by the anti-skid control function unit 19 b is not performed. That is, at the time of anti-skid control, more precise control of the braking force is required as compared to that at the time of normal braking operation, so switching of the variable structure control system can be positively performed to improve control accuracy.

The switching strength determination function unit 21 may have a function to make the gradient in the smoothing switching steeper as the change degree of the braking force command value based on the command unit 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. As a result, control can be performed so that the change in the braking force accurately follows the brake operation, and the brake feeling can be improved.

The switching strength judgment function unit 21 has a function to make the gradient in the smooth switching slower as the braking force command value becomes smaller under the condition that the braking force command value based on the command means 18 is smaller than the defined value. You may have. The predetermined value is a value arbitrarily determined by design or the like, and is determined by obtaining an appropriate value by, for example, one or both of a test and a simulation.

In the case of light brake operation, relatively large operation noise of the electric brake device is easily generated, and chattering leads to deterioration of the NVH. For this reason, when the braking force command value is smaller than the predetermined value, the NVH can be improved by making the gradient in the smooth switching slower.

The switching strength judgment function unit 21 has a function to make the gradient in the smooth switching slower as the braking force command value becomes larger under the condition that the braking force command value based on the command means 18 is larger than the predetermined value. You may have. The predetermined value is a value arbitrarily determined by design or the like, and is determined by obtaining an appropriate value by, for example, one or both of a test and a simulation.

When the braking force is increased to a certain extent, deceleration is performed at a relatively high G, and the control accuracy hardly affects the feeling. In such a case, the slope in the smooth switching can be made slow to improve the NVH and reduce the power consumption.

Furthermore, a vehicle speed estimation means 27 for estimating the vehicle speed of the vehicle equipped with the electric brake device 1 is provided.
The switching strength determination function unit 21 may have a function to make the gradient in the smooth switching steeper as the vehicle speed estimated by the vehicle speed estimation means 27 becomes larger.

When the vehicle speed is large, the road noise is large, so the influence of the operation noise 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 enhanced by improving the brake control accuracy by making the gradient in the smooth switching steeper as the vehicle speed becomes larger.

The control device 2 has a braking force follow-up control function of controlling the operation amount of the friction material 9 by the friction material operating means 6 so as to follow a braking force command value, and the braking force follow-up control function Sliding mode control that calculates a switching function determined from state quantities, derives a binary manipulated variable according to the positive or negative of the switching function, and sets approximately zero of the switching function as a control target,
The switching strength determination function unit 21 is a function of determining the gradient of the smooth switching accompanying the change of the value of the switching function when switching the operation amount of the binary based on the value of the switching function. May be

The control device 2 controls an angular velocity estimating means 25 for estimating the angular velocity of the electric motor 4 and a braking force following control so that the operation amount of the friction material 9 by the friction material operating means 6 follows a braking force command value. A positive efficiency operation control calculator 33 having a control function, which determines the amount of operation of the electric motor 4 when the contact force between the friction material 9 and the brake rotor 8 increases. And the angular velocity estimation of the binary or more operation amount by two or more types of control operation units including the reverse efficiency operation control operation unit 34 that determines the operation amount of the electric motor 4 when the contact force decreases Has a switching function according to the angular velocity estimated by the means 25;
The switching strength determination function unit 21 is a function of determining the gradient of the smooth switching according to the change of the angular velocity when switching the operation amount of the binary or more according to the angular velocity estimated by the angular velocity estimating means 25. May be

Any combination of the at least two configurations disclosed in the claims and / or the description and / or the drawings is included in the present invention. In particular, any combination of two or more of the claims is included in the present invention.

The invention will be more clearly understood from the following description of the preferred embodiments with reference to the accompanying drawings. However, the embodiments and the drawings are for the purpose of illustration and description only and are not to be taken as limiting the scope of the present invention. The scope of the invention is defined by the appended claims. In the accompanying drawings, the same reference numerals in multiple drawings indicate the same or corresponding parts.
It is a figure showing roughly the electric brake equipment concerning a 1st embodiment of this invention. It is a block diagram of the control system of the electric brake device of FIG. It is a figure which shows an example which switches the operation amount by the electrically-driven brake device of FIG. It is a figure which shows another example which switches the amount of operations by the electrically-driven brake device of FIG. FIG. 7 is a flow chart showing an example of changing the gradient of the smooth switching depending on whether or not anti-skid control is performed in the electric brake device of FIG. 1. It is a block diagram which shows the example of the control structure which switches the operation amount in the electrically-driven brake device of FIG. It is a block diagram of a control system of an electric brake device concerning a 2nd embodiment of this invention. FIG. 7 is a diagram showing an example of adjusting the linear gradient θ _SW in the electric brake device of FIG. 6 according to the degree of change of the braking force or the braking force command value. FIG. 7 is a diagram showing another example of adjusting the linear gradient θ _SW in the electric brake device of FIG. 6 according to the degree of change of the braking force or the braking force command value. It is a block diagram of a control system of an electric brake device concerning a 3rd embodiment of this invention. FIG. 9 is a diagram showing an example in which the linear gradient θ _SW is adjusted according to the estimated vehicle speed in the electric brake device of FIG. 8. The electrically-driven brake device which concerns on the 4th Embodiment of this invention WHEREIN: It is a block diagram which shows the other example of the control structure which switches operation amount.

An electric brake system according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 5. The electric brake device is mounted on, for example, a vehicle. As shown in FIG. 1, the electric brake device 1 includes an electric linear actuator DA and a friction brake BR. First, the structures of the electric linear actuator DA and the friction brake BR will be described.

<Structure of electric linear actuator DA and friction brake BR>
As shown in 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 has an electric motor 4, a reduction mechanism 5, a direct acting mechanism 6 as friction material operating means, a parking brake mechanism 7, an angle sensor Sa, and a load sensor Sb.

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

The friction brake BR includes a brake rotor 8 that rotates in conjunction with a wheel WL of the vehicle, and a friction member 9 that contacts the brake rotor 8 to generate a braking force. The friction material 9 is disposed near the brake rotor. The mechanism that generates the braking force by the frictional force may press the friction material 9 against the brake rotor 8 by operating the actuator body AH. The brake rotor 8 and the friction member 9 may be, for example, a disk brake device using a brake disk and a caliper, or may be 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 reduction mechanism 5 reduces 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 rotating shaft 10 It is possible. The

gears

11, 12 and 13 are rotatable in both directions.

The linear motion mechanism 6 is a mechanism that converts the rotational motion output from the speed reduction mechanism 5 into linear motion of the linear motion portion 14 by the feed screw mechanism and causes the friction material 9 to abut or separate from the brake rotor 8. . The linear movement portion 14 is detentated and supported movably in the axial direction A1. A friction material 9 is provided at the outboard side end of the linear movement portion 14. By transmitting the rotation of the electric motor 4 to the linear motion mechanism 6 through the reduction mechanism 5, the rotational motion is converted into a linear motion, which is converted into the pressing force of the friction material 9 to generate a braking force. . When the electric brake device 1 is mounted on a vehicle, the outer side in the vehicle width direction of the vehicle is referred to as the outboard side, and the central side in the vehicle width direction of the vehicle is referred to as the inboard side.

As the parking brake actuator 16 of the parking brake mechanism 7, for example, a linear solenoid is applied. The locking member 15 is advanced by the parking brake actuator 16 and fitted into a locking hole (not shown) formed in the intermediate gear 13 for locking, thereby inhibiting the rotation of the intermediate gear 13, Set the parking lock. By disengaging the lock member 15 from the locking hole, the rotation of the intermediate gear 13 is allowed to be in the unlocked state.

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

The load sensor Sb is a braking force estimation means for estimating the braking force, and is used when controlling the braking force. As the load sensor Sb, for example, a magnetic sensor, a strain sensor, a pressure sensor or the like that detects a displacement or a deformation of a predetermined portion to which 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 load sensorless estimation from the motor angle and the electric brake device stiffness, or the motor current and the efficiency of the electric linear actuator DA. Also, various sensors such as a thermistor may be separately provided according to the requirements.

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

<About control device 2>
FIG. 2 is a block diagram of a control system of the electric brake device 1.
For example, the control device 2 and the actuator body AH corresponding to each wheel WL are provided. Each control device 2 controls the corresponding electric motor 4. The power supply device 3 and the upper control means (not shown) of each control device 2 are connected to each control device 2. The power supply device 3 supplies power to the respective electric motors 4 and the motor drivers 17 of the respective control devices 2. As the upper control means, for example, an electric control unit that controls the whole vehicle is applied. The upper 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 have a brake command value generation function unit 19, a control calculation function unit 20, a switching strength determination function unit 21, a wheel motion estimation means 22, and a wheel speed estimation function unit 23. The wheel motion estimation means 22 has 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 braking force) of the linear motion mechanism 6 from the output of the load sensor Sb and the like. When the load sensorless estimation is performed, 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 or the like. For example, when using a sensor that detects a predetermined angle area as one cycle, such as a resolver or a magnetic encoder, as the angle sensor Sa, the motor motion estimation function unit 25 determines the output of the angle sensor Sa from the rotor of the electric motor 4 The phase may be estimated, and the integrated value of the variation in the rotor phase may be estimated as the total rotation angle (position). Further, a differential equivalent value of the phase or position may be estimated as an angular velocity. Alternatively, for example, in the case of performing the above-described angle sensorless estimation, the motor motion estimation function unit 25 may estimate the phase or angular velocity or the like of the rotor from the motor voltage and the motor current.

The wheel speed estimation function unit 23 is output, for example, within a time period in which one pulse is output, or within a predetermined time, from an output of the wheel speed sensor Sc which outputs a predetermined number of pulses during one rotation of the wheel WL. The number of pulses may be counted, and the wheel speed may be estimated based on a predetermined conversion formula. The wheel speed estimation function unit 23 may be, for example, an estimation method in which the method is switched using a predetermined estimated angular velocity as a threshold. 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 velocity by 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 antiskid command calculation unit 19b. The service brake command computation unit 19a estimates the braking force required for the normal service brake based on the command means 18 such as a brake pedal, for example, and uses it as a braking 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, calculates the degree of slip of the wheel WL relative to the road surface based on the vehicle speed estimated by the vehicle speed estimation means 27 and the wheel speed (estimated value) estimated Anti-skid by calculating the braking force command value without using the command means 18 so as to estimate the slip ratio etc. and to suppress the amount of slippage of the wheel WL when the estimated slippage degree exceeds the threshold value Execute control. Information on whether the service brake command calculation unit 19a performs the calculation or the antiskid command calculation unit 19b performs the calculation is given to the switching strength determination function unit 21.

The vehicle speed estimation means 27 may estimate the vehicle speed from, for example, the longitudinal acceleration of the vehicle estimated by the acceleration estimation means 28, and the estimated wheel speeds of each of the generally provided wheels. The vehicle speed estimation means 27 may use GPS or the like as an element not shown in the drawings or may be used in combination. Furthermore, as an element not shown, for example, brake control means based on vehicle motion such as anti-slip control may be separately provided in the control device 2.

The control calculation function unit 20 has a function of switching a plurality of mutually different operation amounts based on a state amount which is a physical amount including any of a motor angle and a value corresponding to 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 braking force follows the braking force command value requested from 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, converts the brake force into another physical quantity such as an angle, and performs the control calculation. It is also good. The feedback control may be, for example, a calculation structure in which a plurality of minor feedback loops are provided so as to provide a motor current control loop in a braking force control loop, and a structure for calculating motor operation amount in a single feedback loop. It is also good. Alternatively, feed forward control may be used, or feed forward control may be used in combination.

The brake control function unit 26 calculates operation amounts for the plurality of operation amounts according to the predetermined state amount, and operation

amount calculation portions

26 ₁ , 26 ₂ ,... And a switching control unit 30 for calculating a value of a switching parameter which is a parameter for switching in

The operation amount switching function unit 29 has a function of switching and outputting any one of the plurality of operation amounts as an electric brake operation amount based on the plurality of operation amounts and the switching control signal calculated by the brake control function unit 26. . At this time, the operation amount switching function unit 29 is discontinuous such that, for example, the operation amount “1” is replaced with the operation amount “2” with the predetermined threshold in the switching parameter as a boundary in switching the plurality of operation amounts. The function to perform switching operation and the continuous change of the operation amount “1” to the operation amount “2” continuously with the transition of the value of the switching parameter in the predetermined range of the switching parameter And a function to perform smooth switching operation.

In this example, the switching strength judgment function unit 21 judges the steepness of switching necessary for switching the operation amount in the operation amount switching function unit 29 based on the presence or absence of execution of the antiskid control, and the operation amount switching function The switching process in the unit 29 is adjusted. In general, in anti-skid control, while the brake control accuracy is extremely important, the importance of the NVH is often extremely poor.

For this reason, the switching strength determination function unit 21 can perform switching processing having a steepness with emphasis placed on control accuracy at the time of anti-skid control. The judgment of the abruptness of the switching in the switching strength judgment function unit 21 is mainly based on the necessity of the braking force control accuracy and the viewpoint of the NVH, and the switching processing is made steeper as the control accuracy is emphasized and the NVH is emphasized. The switching process can be made slower.

For example, the motor driver 17 constitutes a half bridge circuit using switching elements such as field effect transistors (abbreviated as FET), and performs PWM control to determine a motor applied voltage with a predetermined duty ratio. It is preferable because it is inexpensive and has high performance. Alternatively, the motor driver 17 can be configured to perform PAM control, for example, by providing a transformer circuit or the like.

In addition, a current sensor or the like (not shown) can be appropriately provided as needed. Further, each functional block in FIG. 2 is provided for convenience in describing the function, and may be integrated and divided as necessary, or a predetermined function may be omitted as appropriate.

<Example of switching operation of operation amount>
FIGS. 3A and 3B are diagrams showing an example of switching the operation amount by this electric brake device. Hereinafter, it demonstrates, also referring FIG. In FIG. 3A, the control arithmetic function unit 20 (FIG. 2) switches the binary operation amount (operation amount 1, operation amount 2) via the linear smoothing function Fc in the vicinity of the switching threshold in the predetermined switching parameter. An example is shown. The switching parameters for the horizontal axes in FIGS. 3A and 3B are, for example, state quantities such as the angular velocity of the electric motor 4, dynamics obtained by converting the state quantities into a predetermined characteristic value, 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 parameter.

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

FIG. 4 is a flow chart showing an example of changing the gradient θ _SW of the smoothing function depending on whether or not anti-skid control is in progress in this electric brake system. After the start of this process, the switching strength determination function unit 21 (FIG. 2) determines whether anti-skid control is being performed based on the information of the brake control mode from the brake command value generation function unit 19 (step S1). In the judgment that anti-skid control is being performed (step S1: yes), the switching strength judgment function unit 21 (FIG. 2) makes the gradient θ _{SW of the} smoothing function larger than when anti-skid control is not being performed (step S2). ). Thereafter, the process ends. If it is determined that 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 during anti-skid control (step S3). Thereafter, the process ends.

<Example of control configuration for switching the operation amount>
FIG. 5 is a block diagram showing an example of the configuration of a control system that switches 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 including motor angle etc., a nonlinear input is calculated according to the switching function, and an actual response is converted to the dynamics of the switching function. The example which applies sliding mode control which constrains is shown.

The state estimator corresponding to the wheel motion estimation means 22 can be configured by, for example, a linear state observer or a VSS observer. The state quantity x determined by the state estimator is, for example, a state quantity forming an equation of motion such as motor angle, angular velocity (one-time derivative value of motor angle), angular acceleration (two-time derivative value of motor angle) be able to. In addition, in order to achieve follow-up control of the braking force, a deviation between a predetermined command value and a state quantity, or an integration (integration) value of the deviation can be included.

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

The non-linear input computing unit 32 in the control operation function unit 20 (brake force follow-up control function unit) is a function mainly intended to compensate for disturbance or model error, and a predetermined operation amount + u according to the sign of the switching function σ. , -U, and generates a control input that constrains the state quantity to σ00. At this time, as the switching strength determination function unit 21 makes the switching steeper in the non-linear input computing unit 32, the constraining force to the state quantity σ = 0 becomes stronger, and chattering occurs. In other words, the steeper the switching of the non-linear input, the more advantageous for control accuracy, and the more disadvantageous for NVH and power consumption. The switching strength determination function unit 21 determines the steepness of switching of the non-linear control input based on the determined switching parameter.

<Function effect>
According to the electric brake device 1 described above, the switching strength determination function unit 21 determines the abruptness of switching necessary for switching the operation amount in the operation amount switching function unit 29 based on the presence or absence of execution of the antiskid control. 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, while the importance of the NVH at the time of anti-skid control is often extremely poor. For this reason, the switching strength determination function unit 21 can perform switching processing having a steepness with emphasis placed on control accuracy at the time of anti-skid control. Therefore, both NVH and control accuracy can be achieved.

<Other Embodiments>
In the following description, the portions corresponding to the items described in advance in each embodiment are denoted by the same reference numerals, and the redundant description will be omitted. When only a part of the configuration is described, the other parts of the configuration are the same as those described in the preceding embodiment unless otherwise stated. The same function and effect are exhibited from the same configuration. Not only the combination of the portions specifically described in the embodiments but also the embodiments may be partially combined if any problem does not occur in the combination.

As shown in FIG. 6, the switching strength determination function unit 21 shows a second embodiment in which the switching strength is determined based on one or both of the braking force command value and the estimated braking force. Generally, in the case of light brake operation, relatively large operation noise of the electric brake device 1 is easily generated, and chattering leads to deterioration of the NVH. On the other hand, as the braking force increases, NVH is less likely to deteriorate due to the pressure applied to the mechanical connection in the actuator body AH. For this reason, the switching strength determination function unit 21 makes switching slower as one or both of the braking force command value and the estimated braking force become smaller, and one or both of the braking force command value and the estimated braking force become larger. The switching can be made steeper (left part of FIG. 7A).

Further, when the braking force is increased, the vehicle is decelerated at a relatively high G, and the control accuracy hardly affects the feeling. Therefore, the switching strength determination function unit 21 may perform processing to make switching slower as the braking force command value becomes larger under the condition that the braking force command value is larger than the predetermined value (right part in FIG. 7A).

FIG. 7A shows an example shown in FIG. 6 in which the steepness of the smoothing function is adjusted according to the braking force. The braking force on the horizontal axis in FIG. 7A may use a braking force command value or may use an actual estimated braking force.

FIG. 7B shows an example in which the steepness of the smoothing function is adjusted in accordance with the degree of change of the braking force command value shown in FIG. It is considered that the driver of the vehicle is more sensitive to the degree of change in the braking force as the degree of change (differentiated value or the like) of the braking force command value is slower. Conversely, the steeper the degree of change in the braking force command value, the less likely the driver is to the degree of change in the braking force.

Therefore, as shown in FIGS. 6 and 7B, the switching strength judgment function unit 21 makes the gradient θ _{SW of the} smoothing function steeper as the degree of change in the braking force command value decreases, and the degree of change in the braking force command value increases. The gradient θ _SW may be made as slow as possible.

When the brake pedal is operated gently, the brake control accuracy can be increased by making the gradient in the smoothing function steep. As a result, control can be performed so that the change in the braking force accurately follows the brake operation, and the brake feeling can be improved.

As in the third embodiment shown in FIGS. 8 and 9, the switching strength determination function unit 21 may make the gradient in the smoothing function steeper as the vehicle speed estimated by the vehicle speed estimation means 27 increases. . In general, when the vehicle speed is high, the brake operation noise hardly affects the NVH due to road noise or the like. Conversely, when the vehicle speed is low (in particular, the vehicle is stopped), the influence of the brake operation noise becomes relatively large. The influence of the braking force on the braking distance is relatively large as the vehicle speed is high, and relatively small as the vehicle speed is low. Therefore, the switching strength determination function unit 21 executes processing to make switching steeper as the vehicle speed estimated by the vehicle speed estimation means 27 becomes larger and to make switching slower as the vehicle speed becomes smaller. This is preferable because safety and NVH can be compatible.

Any of the control systems shown in FIGS. 2, 6 and 8 may be used, or may be used in combination as appropriate. 7A, 7B and 9, although the example using linear gradient (theta) _SW of FIG. 3A is shown, you may use width xsw of FIG. 3B. In addition, a variable that defines the steepness at which the operation amount switches with respect to the transition of the predetermined switching function can be used as appropriate.

In the control configuration for switching the amount of operation shown in FIG. 10, the positive efficiency operation control calculator 33 in the pressure increase state, the reverse efficiency operation control calculator 34 in the pressure decrease state, and the hysteresis intermediate control calculator in the hysteresis middle state in the actuator body AH. The 4th embodiment which switches 35 is shown. The pressure-increasing state is synonymous with the state in which the contact force between the friction material 9 (FIG. 1) and the brake rotor 8 (FIG. 1) increases, and the pressure-reducing state is synonymous with the state in which the contact force decreases. It is.

Generally, in an electric linear actuator such as that used for an electric brake device, even when the thrust is the same, the load (positive efficiency) at the time of pressure increase by rotational motion from the electric motor and the load (reverse efficiency) at the pressure decrease Is different. In other words, in the forward efficiency operation and the reverse efficiency operation, it can be considered that the systems have different equivalent spring rates. Further, in the operation in the middle of the hysteresis, in particular, the actuator main body does not operate with respect to the change of the motor torque (motor current), and therefore, the control becomes an uncontrollable state.

Therefore, as shown in FIG. 10, the control calculation function unit 20 which is a brake force follow-up control function unit uses the forward efficiency operation control computing unit 33 using the parameters in the forward 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 hysteresis are provided. It is preferable to use, for example, a linear controller such as a deviation compensator or a state feedback device as each of the control computing devices, because the number of design steps and the computational load can be reduced. Further, in particular, the hysteresis intermediate control computing unit 35 may be implemented as a controller that controls the motor current to be a predetermined torque when the actuator main body AH is set as the inoperable control state in which it 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 the pressure increase, pressure decrease or hysteresis intermediate state. In other words, the manipulated variable switching function unit 29 applies the manipulated variable of the positive efficiency operation control calculator 33 when the polarity of the angular velocity given from the state estimator 22 is in the pressure increasing direction (positive) as the switching parameter, When the polarity of the angular velocity is in the pressure reduction direction (negative) as the switching parameter, the operation amount of the reverse efficiency operation control computing unit 34 is applied. The operation amount switching function unit 29 applies the hysteresis intermediate control computing unit 35 as the switching parameter when the polarity of the angular velocity is substantially zero.

At this time, the switching strength determination function unit 21 can use the motor angular velocity as the switching function, and can appropriately set the gradient of the smooth switching in the vicinity of the threshold angular velocity zero. Hysteresis intermediate control operation unit 35 may be omitted in a transient response state in the middle of following a predetermined braking force, and may be applied only in the case of following a braking force command value which is substantially constant.

When switching the plurality of operation amounts in the control operation function unit 20 shown in FIG. 3A, the switching strength determination function unit 21 changes the steepness of the smooth switching with respect to a predetermined switching parameter. A configuration in which θ _SW is 90 degrees may be included. When the gradient θ _SW is 90 degrees, smooth switching is not performed. Further, the switching strength determination function unit 21 is a smoothing function in the case of changing the steepness of smooth switching with respect to a predetermined switching parameter in switching of a plurality of operation amounts in the control calculation function unit 20 shown in FIG. 3B. A configuration in which the width xsw from the switching start to the end in Fc is zero may be included. When the width xsw is zero, smooth switching is not performed.

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

The load sensor Sb may be, for example, a wheel torque of a wheel on which a brake is mounted, a sensor for detecting a longitudinal force of a vehicle on which the electric brake device is mounted, or the like instead of the above-described sensor or the like.

As described above, although the preferred embodiments have been described with reference to the drawings, various additions, modifications or deletions can be made without departing from the spirit of the present invention. Therefore, such is also included in the scope of the present invention.

1 ... electric brake device 2 ... control device 4 ... electric motor 6 ... linear motion mechanism (friction material operation means)
DESCRIPTION OF SYMBOLS 8 ... Brake rotor 9 ... Friction material 18 ... Command means 20 ... Control calculation function part 21 ... Switching strength judgment function part 22 ... Wheel movement estimation means

Claims

Brake rotor,
A friction material that generates a braking force in contact with the brake rotor,
Electric motor,
Friction material operation means for converting the output of the electric motor into pressing force of the friction material;
A control device for controlling an output of the electric motor based on a braking force command value given from a command means;
The controller is
A wheel motion estimating means for estimating an angle in rotational motion of a wheel synchronized with the brake rotor and a predetermined order differential value of the angle;
A control calculation function unit that switches an operation amount among a plurality of operation amounts different from each other according to a state amount that is a physical amount including at least one of an angle of rotation of the electric motor and a value corresponding to a predetermined differential value of this angle; ,
Based on one or both of the braking force command value from the command means and the estimated value estimated by the wheel motion estimation means, 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 smoothing switching, which is control for continuously switching from the current operation amount to the operation amount after switching, with respect to a predetermined switching parameter in switching of the operation amount in the control calculation function unit. An electric brake device having one or both of a function of determining whether or not it is, and a function of changing a slope indicating the steepness of the smooth switching with respect to a predetermined switching parameter.
The electric brake device according to claim 1, wherein the acceleration estimation means estimates a longitudinal acceleration of a vehicle on which the electric brake device is mounted;
Vehicle speed estimation means for estimating the vehicle body speed of the vehicle based on either or both of the longitudinal acceleration estimated by the acceleration estimation means and the estimated value estimated by the wheel motion estimation means;
The control device further estimates the degree of slippage of the wheel relative to the road surface based on the estimated value estimated by the wheel motion estimation means and the vehicle speed estimated by the vehicle speed estimation means, and the slippage estimated It has an anti-skid control function unit that calculates a braking force command value regardless of the command means so as to suppress the slippage of the wheel when the degree exceeds a threshold.
The switching strength judgment function unit makes the gradient in the smooth switching when the control by the anti-skid control function unit is sharpened compared to the case where the control by the anti-skid control function unit is not performed. Electric brake device.
The electric brake device according to claim 1 or 2, wherein the switching strength judgment function unit makes the gradient in the smooth switching steeper as the degree of change of the braking force command value based on the command means becomes smaller. And an electric brake device.
The electric brake device according to any one of claims 1 to 3, wherein the switching strength judging function unit is configured to set the braking force under a condition that a braking force command value based on the command means is smaller than a predetermined value. The electric brake device which has a function which makes the gradient in the said smooth switching slow, so that a command value becomes small.
The electric brake device according to any one of claims 1 to 4, wherein the switching strength determination function unit is configured to set the braking force under a condition that a braking force command value based on the command unit is larger than a predetermined value. The electric brake device which has a function which makes the gradient in the said smooth switching slow, so that a command value becomes large.
The electric brake system according to any one of claims 1 to 5, further comprising a vehicle speed estimation means for estimating a vehicle speed of a vehicle equipped with the electric brake system,
The electric braking device has a function of making the gradient in the smooth switching steeper as the vehicle speed estimated by the vehicle speed estimation means becomes larger.
The electric brake system 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 to follow a braking force command value. It has a force tracking control function, and this brake force tracking control function calculates a switching function determined from the state quantity, derives a binary operation amount according to the positive or negative of the switching function, and Sliding mode control whose control target is approximately zero,
The switching strength determination function unit is an electric brake device having a function of determining a slope of the smooth switching accompanying a change in the value of the switching function when switching the operation amount of the binary according to the value of the switching function. .
The electric brake system according to any one of claims 1 to 7, wherein the control device is an angular velocity estimation means for estimating an angular velocity of the electric motor, and an operation amount of the friction material by the friction material operation means. And a brake force follow-up control function of controlling the brake force follow-up value, and the brake force follow-up control function is for the electric motor when the contact force between the friction material and the brake rotor increases. Two values by two or more types of control operation devices, including a forward efficiency operation control operation device that determines an operation amount, and a reverse efficiency operation control operation device that determines the operation amount of the electric motor when the contact force decreases. It has a function of switching the above-mentioned operation amount in accordance with the angular velocity estimated by the angular velocity estimating means,
The switching strength determination function unit is an electric brake having a function of determining a slope of smooth switching accompanying a change in the angular velocity when switching the operation amount of two or more values according to the angular velocity estimated by the angular velocity estimating means. apparatus.