WO2016199709A1

WO2016199709A1 - Electric braking device

Info

Publication number: WO2016199709A1
Application number: PCT/JP2016/066720
Authority: WO
Inventors: 唯増田; 山崎　達也
Original assignee: Ntn株式会社
Priority date: 2015-06-11
Filing date: 2016-06-06
Publication date: 2016-12-15
Also published as: JP2017001559A; JP6466261B2

Abstract

An electric braking device is provided such that the cost can be reduced while achieving improved control accuracy in a regular range of use. This electric braking device is provided with: a brake rotor; a friction member; a friction member actuation means; an electric motor (4); a braking force estimation means (17) for determining an estimated braking force, that is, an estimated value of a braking force generated when the friction member is pressed against the brake rotor; and a control device (2) for controlling the electric motor (4) such that the estimated braking force approaches a target braking force. The control device (2) has an estimation range change means (26) for changing, on the basis of the target braking force and/or the estimated braking force, or both, limit values of the estimated braking force estimation range used by the braking force estimation means (17).

Description

Electric brake device

Related applications

This application claims the priority of Japanese Patent Application No. 2015-118585 filed on June 11, 2015, and is incorporated herein by reference in its entirety.

The present invention relates to an electric brake device, and more particularly to a technique capable of reducing costs while improving control accuracy in a normal range.

The electric brake device includes, for example, a motor that is a drive source, a speed reducer, a friction member operating means including a linear motion mechanism, and a brake rotor that rotates together with wheels. In this electric brake device, the frictional force between the friction member and the brake rotor is controlled so as to generate an appropriate braking force based on the pedal operation amount (stepping force, stroke, etc.) of the driver and the state of the vehicle. At that time, a brake force sensor that estimates the brake force is used to control the brake force with high accuracy. As the brake force sensor, the present applicant has proposed a technique of applying a load sensor using a magnetic sensor (Patent Documents 1 to 6, etc.).

JP 2013-29413 A JP 2013-32970 A JP 2013-83550 A JP 2013-257000 A JP 2014-16307 A JP 2014-134450 A

Generally, vehicle brakes are usually used at a deceleration of about 0.2 G or less, for example. At that time, the driver controls the brake finely by operating a pedal or the like in accordance with the behavior of the vehicle. For this reason, in the brake force sensor for controlling the brake force with high accuracy, sufficient detection accuracy is required in order not to make the driver feel uncomfortable. On the other hand, during sudden braking where a large vehicle deceleration is required, it is rare for the driver to control the pedal finely according to the feeling, and even if the detection accuracy of the brake force sensor is relatively rough. There seems to be no problem.

Also, as a means for estimating the brake force, a brake load sensor for detecting the axial load of the linear motion mechanism as in the prior art can be constructed at a relatively low cost, which is useful. In that case, the electric brake device controls the pressing force between the friction member and the brake rotor. In that case, the friction coefficient between a friction member and a brake rotor changes with the temperature. For example, it is known that the friction coefficient between the friction member and the brake rotor may be about ３ (fading phenomenon) when intense braking is repeated from high speed traveling.

Therefore, the brake load sensor is required to have a dynamic range for detecting a pressing force assuming a fade phenomenon. However, as a result, it may be difficult to obtain sufficient resolution in the normal range where the fade phenomenon does not occur. As described above, if the brake force sensor is set to a dynamic range that assumes a relatively infrequent situation, it is necessary to configure a high-accuracy load sensor in order to obtain sufficient resolution in the normal range, which may result in high costs. There is.

An object of the present invention is to provide an electric brake device capable of reducing costs while improving control accuracy in a normal range.

Hereinafter, in order to facilitate understanding, the present invention will be described with reference to the reference numerals of the embodiments for convenience.

The electric brake device according to the present invention includes a brake rotor 8, a friction member 9 that makes contact with the brake rotor 8, friction member operation means 6 that makes the friction member 9 contact the brake rotor 8, and this friction member operation means 6. An electric motor 4 for driving the brake, a brake force estimating means 17 for obtaining an estimated brake force which is an estimated value of a brake force generated by pressing the friction member 9 against the brake rotor 8, and controlling the electric motor 4. An electric brake device including a control device 2 that controls the estimated brake force to follow the target brake force,
The controller 2 changes the limit value of the estimated range of the estimated brake force by the brake force estimating means 17 based on one or both of the target brake force and the estimated brake force. Have

According to this configuration, the control device 2 controls the electric motor 4 to drive the friction member operating means 6 when the driver of the vehicle equipped with the electric brake device performs a brake operation. Thereby, the friction member operating means 6 generates a braking force by pressing the friction member 9 against the brake rotor 8. When controlling the electric motor 4, the control device 2 controls the estimated brake force obtained by the brake force estimating means 17 so as to follow the target brake force.

The estimated range changing means 26 of the control device 2 changes the limit value of the estimated range of the estimated brake force by the brake force estimating means 17 based on one or both of the target brake force and the estimated brake force. When the normal range and the non-normal range in the estimated braking force can be assumed to some extent as in the electric brake device, for example, the estimation range is set to the normal range, and the limit value of the estimation range is changed as necessary. This makes it easy to achieve the necessary resolution for each estimated range of the estimated braking force. Therefore, it is possible to reduce the cost without configuring a highly accurate load sensor as in the prior art, to improve the control accuracy in the normal range, and to provide sufficient detection accuracy to prevent the driver from feeling uncomfortable. can get. In addition, it is possible to detect a wide range of braking force necessary for sudden braking.

The estimated range changing means 26 includes the following condition group:
When one or both of the target braking force and the estimated braking force exceed a threshold value in the estimated range,
When the absolute value of the deviation between one or both of the braking forces and the threshold value in the estimated range is within a predetermined value and the amount of change in either one or both of the braking forces is greater than or equal to a predetermined value, and either When the excess time when one or both braking forces exceed the threshold exceeds a predetermined time,
The limit value of the estimation range may be changed to be larger than the limit value before the change based on at least one of the conditions. The threshold value is determined by results of tests, simulations, and the like (hereinafter the same).

According to this configuration, as a precondition for expanding the limit value of the estimated range, at least one of the target brake force and the estimated brake force, for example, the target brake force, exceeds the threshold value in the estimated range. At this time, it is preferable to provide hysteresis with a threshold value that is larger than a threshold value for reducing the limit value of the estimation range described later after the limit value is expanded, because frequent changes in the estimation range can be prevented. Further, when the estimated range changing means 26 expands the limit value of the estimated range based on the excess amount, the calculation process can be simplified and the calculation processing load of the control calculation can be reduced.

When the estimated range changing means 26 expands the limit value of the estimated range based on the amount of change of the target brake force, for example, a differential value, or when the target brake force increases sharply, the estimated range changes according to the tendency of the target brake force. The limit value of can be expanded. For example, when the target braking force increases and approaches the threshold value steeply, it is predicted that the threshold value will be exceeded immediately thereafter, and the limit value of the estimated range can be changed quickly. When the estimated range changing means 26 expands the limit value of the estimated range based on the excess time, the limit value of the estimated range is changed when the target braking force exceeds the threshold value for a short time. It can be excluded from the conditions. The predetermined short time is determined by a result of a test or simulation.

The estimated range changing means 26 includes the following condition group:
When one or both of the target braking force and the estimated braking force falls below a threshold value in the estimated range,
When the absolute value of the deviation between one or both of the braking forces and the threshold value in the estimated range is within a predetermined value and the amount of change in either one or both of the braking forces is less than or equal to a predetermined value; When the time during which one or both braking forces are below the threshold exceeds a predetermined time,
The limit value of the estimation range may be changed to be smaller than the limit value before the change based on a condition including at least one of them. The estimated range is determined by results of tests, simulations, and the like (hereinafter the same).

According to this configuration, as a precondition for reducing the limit value of the estimated range, it is assumed that at least one of the target brake force and the estimated brake force, for example, the target brake force is below a threshold value in the estimated range. Yes. At this time, if the threshold value for reduction is set smaller than the threshold value for expanding the limit value again after reduction of the estimated limit value and a hysteresis is provided, frequent changes in the estimation range can be prevented. Is preferred. Further, when the estimated range changing means 26 reduces the limit value of the estimated range based on the absolute value of the difference, it can be a simple determination, and the calculation processing load of the control calculation can be reduced.

When the estimated range changing means 26 reduces the limit value of the estimated range based on the amount of change of the target brake force, for example, a differential value, for example, it is predicted that the target range will soon fall below the threshold according to the decreasing tendency of the target brake force. The limit value of the estimation range can be reduced. When the limit value of the estimated range is reduced based on the time when the target brake force falls below the threshold value, the condition for changing the limit value of the estimated range when the target brake force falls below the threshold value for a short time Can be excluded.

Note that the estimated braking force may be used instead of the target braking force, or both may be used. The differential value may be a differential value of a difference from a threshold value.

A rotation angle estimating means 24 for estimating the rotation angle of the electric motor 4 is provided, and the brake force estimating means 17 is determined after the estimated range changing means 26 has changed the limit value of the estimated range of the estimated brake force. The estimated braking force may be obtained based on a predetermined relationship between the rotational angle estimated by the rotational angle estimating means 24 and the braking force within a predetermined time. The predetermined time and the predetermined relationship are determined by the results of tests and simulations, respectively.

When it is necessary to change the limit value of the estimated range of the estimated brake force, after changing the limit value of the estimated range, the control device 2 uses the brake force sensor or the like for a predetermined time. The electric brake device is controlled without using the estimation result. In other words, if the relationship between the rotation angle estimated by the rotation angle estimation means 24 and the braking force is measured to some extent, rough control is possible although the control accuracy is lower than that using a braking force sensor or the like. If the predetermined time is a short time, it is considered that there is no practical problem.

The brake force estimating means 17 may include a load sensor that estimates a pressing force when the friction member 9 presses the brake rotor 8.

Rotor angular velocity estimating means 28 for estimating the rotational angular velocity of the brake rotor 8 is provided,
The control device 2 is provided with temperature estimation means 29 for estimating the temperature of the brake rotor 8 from the rotational angular speed estimated by the rotor angular speed estimation means 28,
The estimated range changing unit 26 expands the limit value of the estimated range from the limit value before the change when the temperature estimated by the temperature estimating unit 29 is equal to or higher than a predetermined temperature, and the temperature estimating unit 29 When the estimated temperature becomes lower than a predetermined temperature, the limit value of the estimated range may be changed to be smaller than the limit value before the change.
The predetermined temperature is determined based on results of tests, simulations, and the like.

When the friction member 9 is pressed against the brake rotor 8, the friction coefficient between the friction member 9 and the brake rotor 8 changes depending on the temperature. Then, the limit value of the estimated range is changed based on the heat generated due to pressing the friction member 9 against the brake rotor 8. According to this configuration, the temperature estimating means 29 estimates the temperature of the brake rotor 8 from the rotational angular speed estimated by the rotor angular speed estimating means 28. The estimated range changing means 26 expands the limit value of the estimated range from the limit value before the change when the estimated temperature is equal to or higher than a predetermined temperature. The estimated range changing means 26 reduces the limit value of the estimated range from the limit value before the change when the estimated temperature becomes lower than the predetermined temperature. Therefore, it is possible to finely change the limit value of the estimation range corresponding to the variation of the friction coefficient between the friction member 9 and the brake rotor 8.

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

The present invention will be understood more clearly from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustration and description only and should not be used to define 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 a plurality of drawings indicate the same or corresponding parts.

It is a figure showing the schematic structure of 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 schematically an example of the brake force estimation means of the same electric brake device. It is a figure which shows the relationship between the estimation range of the brake force estimation means of the same electric brake device, and resolution. 5 is a flowchart illustrating an example in which a threshold value for a target brake force is provided when changing the estimated range of the estimated brake force in the electric brake device. It is a flowchart which shows the example which provides a target brake, a threshold value, and a counter when changing the estimation range of the estimated brake force. 7 is a flowchart showing an example of changing an estimated range of an estimated brake force based on a heat generation amount of each wheel estimated from a brake force and a vehicle speed in a vehicle equipped with an electric brake device according to another embodiment of the present invention. . 6 is a flowchart illustrating an example in which the electric motor is controlled without using the brake force estimation result within a predetermined time after changing the limit value of the estimated range of the estimated brake force. It is a figure which shows the change of the estimation range according to the change of the brake force. It is a block diagram which shows the example of the brake force estimation means of the electric brake device which concerns on further another embodiment of this invention.

An electric brake device according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the electric brake device DB includes an electric actuator 1, a control device 2, and a brake force estimating means 17 (FIG. 2). First, the electric actuator 1 will be described.

The electric actuator 1 includes an electric motor 4, a speed reducing mechanism 5 that decelerates the rotation of the electric motor 4, a linear motion mechanism 6 that is a friction member operating means, a parking brake mechanism 7 that is a parking brake, a brake rotor 8, And a friction member 9. The electric motor 4, the speed reduction mechanism 5, and the linear motion mechanism 6 are incorporated in, for example, a housing not shown. The brake rotor 8 may be a disk type or a drum type. The friction member 9 includes a brake pad or a brake shoe. The linear motion mechanism 6 includes a feed screw mechanism such as a ball screw mechanism or a planetary roller screw mechanism.

The electric motor 4 is composed of a three-phase synchronous motor or the like. The speed reduction mechanism 5 is a mechanism that reduces and transmits the rotation of the electric motor 4 to a tertiary gear 11 fixed to the rotary shaft 10, and includes a primary gear 12, an intermediate (secondary) 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 that converts 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 causes the friction member 9 to contact or separate from the brake rotor 8. . The linear motion portion 14 is supported so as to be prevented from rotating and movable in the axial direction A1. A friction member 9 is provided at the outboard side end of the linear motion portion 14. By transmitting the rotation of the electric motor 4 via the speed reduction mechanism 5 to the linear motion mechanism 6, the rotational motion is converted into a linear motion, which is converted into the pressing force of the friction member 9 to generate a braking force. . The outboard side means that the electric brake device DB is mounted on each wheel (not shown) of the vehicle, the vehicle width direction outer side of the vehicle is called the outboard side, and the vehicle width direction center side of the vehicle is the inboard The side.

The parking brake mechanism 7 includes a lock member 15 and an actuator 16. A plurality of locking holes (not shown) are formed at regular intervals in the circumferential direction on the end face of the intermediate gear 13 on the outboard side. The lock member 15 is configured to be able to be locked in any one of these locking holes. For example, a solenoid is applied as the actuator 16. A lock member (solenoid pin) 15 is advanced by an actuator 16 and engaged by being fitted into the engagement hole formed in the intermediate gear 13, and the parking gear is locked by prohibiting rotation of the intermediate gear 13. Put it in a state. By retracting the lock member 15 to the actuator 16 and removing it from the locking hole, the rotation of the intermediate gear 13 is allowed and the unlocked state is achieved.

The control device 2 will be described. As shown in FIG. 2, the control device 2 is a device that controls the electric actuator 1 (FIG. 1) that is a control target, and controls the electric motor 4 to control the brake force to follow the target brake force. It has a function. The control device 2 is connected to a host ECU 3 that is a host control means of the control device 2. For example, an electric control unit that controls the entire vehicle is applied as the host ECU 3. The host ECU 3 is provided with a brake force command means 3a. The brake force command means 3a is an LUT (Look Up Table) implemented by software or hardware in accordance with the output of the sensor 18a that changes according to the amount of operation of the brake pedal 18 that is a brake operation means, or software. Generates and outputs a target braking force command value, that is, a target braking force, using a predetermined conversion function stored in the Library of the library or equivalent hardware (hereinafter referred to as an “implementation model”). To do.

The control device 2 includes an inverter device 19. The inverter device 19 includes a power circuit unit 20 provided for each electric motor 4, a motor control unit 21 that controls one or more power circuit units 20, Current detection means 22. The motor control unit 21 includes a computer having a processor, a ROM (Read Only Memory) having a program executed by the processor, and other electronic circuits such as a RAM (Random Access Memory) and a coprocessor (Co-Processor). Is done.

The motor control unit 21 outputs a (motor) current command represented by a voltage value according to the target brake force given from the brake force command unit 3a and the estimated brake force estimated by the brake force estimation unit 17 (described later). The current command is converted and given to the power circuit unit 20. The motor control unit 21 has a function of outputting information such as detection values and control values regarding the electric motor 4 to the host ECU 3.

The power circuit unit 20 includes an inverter 20a that converts the DC power of the power source 23 into three-phase AC power used to drive the electric motor 4, and a PWM control unit 20b that controls the inverter 20a. The electric motor 4 is provided with rotation angle estimation means 24 for estimating the rotation angle of a rotor (not shown). The inverter 20a includes a plurality of semiconductor switching elements (not shown), and the PWM control unit 20b performs pulse width modulation on the input current command, and gives an on / off command to the gate terminal of each semiconductor switching element, for example. .

The motor control unit 21 includes a motor drive control unit 25 as a basic control unit. The motor drive control unit 25 converts the current command based on the voltage value in accordance with the target brake force and the estimated brake force, and gives a motor operation command value including the current command to the PWM control unit 20b. The motor drive control unit 25 obtains a motor current that flows from the inverter 20a to the electric motor 4 from the current detection unit 22 and performs current feedback control with respect to the target brake force. Further, the motor drive control unit 25 obtains the rotation angle of the rotor (not shown) of the electric motor 4, that is, the motor rotation angle from the rotation angle estimating means 24 so that the motor can be efficiently driven according to the motor rotation angle. The current command is given to the PWM controller 20b.

The motor control unit 21 is provided with an estimated range changing unit 26, a recording unit 27, and the like. The estimated range changing means 26 changes the limit value of the estimated range of the estimated brake force by the brake force estimating means 17 based on one or both of the target brake force and the estimated brake force. The brake force estimating means 17 obtains an estimated brake force that is an estimated value of the brake force generated by pressing the friction member 9 (FIG. 1) against the brake rotor 8 (FIG. 1).

The brake force estimating means 17 converts a load sensor 17a that detects a pressing force when the friction member 9 (FIG. 1) presses the brake rotor 8 (FIG. 1), and converts an analog output of the load sensor 17a into a digital signal. An A / D converter 17b and a relationship setting unit 17c described later are included. In the present embodiment, the A / D converter 17b corresponds to a variable type in which the estimation range of the braking force is variable by an external input to a change input terminal (not shown), that is, the maximum value of the output digital signal. This is a variable type in which the maximum value of the analog input signal is variable.

The load sensor 17a includes, for example, a magnetic sensor 17aa (FIG. 3) and a magnetic target 17ab. The magnetic target 17ab has, for example, two permanent magnets 17ba and 17ba. As shown in FIGS. 1 and 3, when the friction member 9 presses the brake rotor 8, a reaction force to the inboard side acts on the linear motion mechanism 6. The load sensor 17a including the magnetic sensor 17aa and the magnetic target 17ab magnetically detects the reaction force of the braking force as an axial displacement amount.

As a magnetic sensor 17aa for detecting a change in magnetic field, a Hall IC with a variable dynamic range and an inexpensive price is commercially available, and is highly available. As the magnetic sensor 17aa, for example, a magnetoresistive element or a magnetic impedance element may be applied in addition to the Hall IC.

As shown in FIG. 2, the relationship setting means 17c of the brake force estimating means 17 is a digital signal obtained by A / D converting the sensor output consisting of an analog signal by the A / D converter 17b and the reaction force of the brake force. By obtaining the relationship in advance by tests, simulations, etc., and storing the relationship in LUT, the braking force can be estimated based on the sensor output of the load sensor 17a. As the load sensor 17a, an optical sensor other than the magnetic sensor, an eddy current sensor, or a capacitance sensor can be applied.

The estimated range changing unit 26 changes the limit value of the estimated range of the estimated brake force obtained by the brake force estimating unit 17 described above. Here, FIG. 4 is a diagram showing the relationship between the estimation range and the resolution of the braking force estimation means 17 of this electric brake device. In a predetermined estimation range (1) by the brake force estimation means 17 (FIG. 2) and an estimation range (2) wider than the estimation range (1), the resolution in each range is generally the resolution α of the A / D converter 17b. Depends on _A.

In servo motor control such as the electric brake device according to the present embodiment, a microcomputer, a field programmable gate array (abbreviated as FPGA: field-programmable gate array), a digital signal processor (abbreviated as DSP: digital signal processor), etc. It is conceivable to use it. For example, as an inexpensive A / D converter for the arithmetic unit, generally 10-bit (1024 divisions) to 12-bit (4096 divisions) are widely used.

In this embodiment, as shown in FIGS. 2 and 4, the resolution α _A of the A / D converter 17b of the brake force estimating means 17 is constant regardless of the range of the estimation range, and this A / D converter If 17b of the resolution alpha _a can maximally use, the estimated braking force F2 of the estimated range (2), when the estimated braking force F1 of the estimated range (1) (where F2> F1), the estimated range (2), (1 ) Is expressed as follows.
Resolution in estimation range (2) = F2 / α _A
Resolution in estimation range (1) = F1 / α _A
As described above, the resolution α _{A of} the A / D converter 17b is constant, the resolution α _A is fully used, and F2> F1 regardless of the range of the estimation range. The resolution F1 / α _{A in} the estimation range (1) having a narrow measurement range is higher than the resolution F2 / α _{A in} ().

Therefore, as shown in FIG. 2, the estimated range changing unit 26 determines the estimated braking force in the A / D converter 17 b of the braking force estimating unit 17 based on one or both of the target braking force and the estimated braking force. Change the limit value of the estimated range. When the normal range and the non-normal range in the estimated braking force can be assumed to some extent as in the electric brake device, for example, the estimation range is set to the normal range, and the estimation range changing unit 26 sets the limit value of the estimation range as necessary. change.

Specifically, the estimated range changing means 26 has the following condition group and target brake force (here, the target brake force is an example of one or both of the target brake force and the estimated brake force): When the threshold in the estimated range is exceeded, the absolute value of the difference between the target braking force and the threshold is less than or equal to a predetermined value, and the amount of change in the target braking force, for example, the differential value is greater than or equal to a predetermined value, and When the time exceeds the predetermined time, the limit value of the estimation range of the A / D converter 17b is changed to be larger than the limit value before the change based on a condition including at least one of them. The threshold value is determined by the result of the test or simulation, and is stored in the recording means 27 so as to be rewritable.

Suppose that the target braking force exceeds the threshold in the estimated range as a precondition for expanding the limit value of the estimated range. At this time, it is possible to prevent frequent changes in the estimation range by setting a threshold value that is larger than a threshold value for reducing the estimation range, which will be described later, and providing hysteresis. Further, when the estimated range changing means 26 expands the limit value of the estimated range based on the excess amount, the calculation process can be simplified and the calculation processing load of the control calculation can be reduced.

When the estimated range changing means 26 expands the limit value of the estimated range based on the amount of change of the target brake force, for example, a differential value, the estimated range is increased according to the increasing tendency of the target brake force, for example, the target brake force increases sharply. The limit value of can be expanded. For example, when the target braking force approaches the threshold value steeply, it is predicted that the threshold value will be exceeded immediately after that (even if the absolute value of the deviation between the threshold value and the target braking force is within a predetermined value). In addition, the limit value of the estimated range can be quickly changed. When the estimated range changing means 26 expands the limit value of the estimated range based on the excess time, the limit value of the estimated range is changed when the target braking force exceeds the threshold value for a short time. It can be excluded from the conditions.

Further, the estimated range changing means 26 is configured so that the following condition group, the target brake force (the target brake force of one or both of the target brake force and the estimated brake force is taken as an example here) is the estimated range. When the absolute value of the difference between the target brake force and the threshold is less than or equal to a predetermined value and the rate of change of the target brake force is less than or equal to a predetermined value, and when the target brake force is less than the threshold May be changed so that the limit value of the estimation range is reduced from the limit value before the change based on a condition including at least one of them. In the present specification, the estimated range, the predetermined time, the predetermined temperature, and the like are determined by results of tests, simulations, and the like, and are stored in the recording unit 27.

前提 As a precondition for reducing the limit value of the estimated range, it is assumed that the target braking force is below the threshold value in the estimated range. At this time, if the threshold value is set smaller than the threshold value for increasing the estimated range again after the estimated range is reduced and a hysteresis is provided, frequent changes in the estimated range can be prevented. In addition, when the estimated range changing unit 26 reduces the limit value of the estimated range based on the determination that the estimated range is below the threshold, the calculation processing load of the control calculation can be reduced.

When the estimated range changing means 26 reduces the limit value of the estimated range based on the amount of change of the target brake force, for example, a differential value, for example, it is predicted that the target range will soon fall below the threshold according to the decreasing tendency of the target brake force. The limit value of the estimation range can be reduced. When the limit value of the estimated range is reduced based on the time when the target brake force falls below the threshold, the limit value of the estimated range is changed when the time when the target brake force falls below the threshold is a short time It can be excluded from the conditions.

FIG. 5 is a flowchart illustrating an example in which threshold values for the target brake force are provided when the estimated range of the estimated brake force is changed in the electric brake device. Hereinafter, description will be given with reference to FIG. After the start of this process, the estimated range changing means 26 sets a target brake force threshold F _the (F _the : target brake force threshold (range expansion)) when expanding the estimated range (step a1), and the estimated range. Is set to a target brake force threshold F _thd (F _thd : target brake force threshold (range reduction)) (step a2).

The target brake force threshold F _the is determined by multiplying the measurement range R _n (R ₁ <R ₂ <...) Of the estimated brake force by an arbitrary constant α, and the target brake force threshold F _thd is arbitrary in the measurement range R _n . It is determined by multiplying by a constant β. However, 0 ≦ β ≦ α ≦ 1. These target brake force thresholds are respectively stored in the recording means 27 and read out as necessary.

Next, the estimated range changing means 26 determines whether or not the target brake force F _r given from the host ECU 3 is equal to or greater than the target brake force threshold F _the (step a3). In the determination of the target braking force F _r is the target braking force threshold F _the above (Step a3: yes), the estimated range changing means 26, "1" limit value n of the current estimation range (measuring range) larger (Step a4). This limit value n indicates, for example, the number of limit value patterns in an estimated range prepared by numbering in ascending order. Thereafter, this process is terminated.

In the determination of the target braking force _{F r} is less than the target brake force threshold _{F the} (step a3: no), the process proceeds to step a5. In this step a5, the estimation range changing unit 26, when the target braking force _{F r} from the upper ECU3 is determined to be equal to or less than the target brake force threshold _{F thd} (step a5: yes), the estimated range changing means 26, The limit value n of the current estimated range (measurement range) is reduced by “1” (step a6). Thereafter, this process is terminated. Target braking force _{F r} is the determination of the target braking force threshold _{F thd} larger (Step a5: no), the process ends.

According to the implementation example of FIG. 5, the threshold value determination is performed as a precondition for enlarging and reducing the limit value of the estimation range (steps a3 and a5), and so-called predetermined hysteresis is provided. It is possible to prevent a change in the estimated range.

FIG. 6 is a flowchart illustrating an example in which a target brake, a threshold value, and a counter are provided when the estimated range of the estimated brake force is changed. After the start of this process, the estimated range changing means 26 sets a target brake force threshold value F _th (F _th : target brake force threshold) (step b1). The target brake force threshold F _th is determined by multiplying the measurement range R _n (R ₁ <R ₂ <...) Of the estimated brake force by an arbitrary constant γ. However, 0 ≦ γ ≦ 1.

Then estimation range changing unit 26 determines whether or not the target braking force _{F r} from the upper ECU3 is target braking force threshold _{F th} or more (step b2). In the determination of the target braking force F _r is the target braking force threshold F _th or more (Step b2: yes), the estimation range changing unit 26 performs updating to add "1" to the counter C _e for range extension ( step b3), and resets the counter _{C d} for the range reduced to "0" (step b4). Counter C _e is for target braking force F _r is measuring the time from when the target braking force threshold F _th or more.

Next, the estimated range changing means 26 determines whether or not the counter C _e updated in step b3 is equal to or greater than the range expansion counter threshold C _the (C _the : counter threshold (range expansion)) (step b5). ). Counter _{C e} is the determination of the at counter threshold _{C the} above (Step b5: yes), the estimated range changing means 26 "1" larger limit value n of the current estimation range (step b6). Thereafter, this process is terminated. Counter _{C e} is the determination that it is less than the counter threshold _{C the} (Step b5: no), the process ends.

In step b2, it is determined in the target braking force _{F r} is less than the target brake force threshold _{F th} (Step b2: no), the counter _{C e} for range extension is reset to "0" (step b7), range Update is performed by adding “1” to the counter C _d for reduction (step b8). Note counter C _d is for target braking force F _r is measuring the time from when below the target braking force threshold F _th. Next, the estimated range changing means 26 determines whether or not the counter C _d updated in step b8 is equal to or greater than the range reduction counter threshold C _thd (C _thd : counter threshold (range reduction)) (step b9). ).

When it is determined that the counter C _d is equal to or greater than the counter threshold C _thd (step b9: yes), the estimation range changing unit 26 reduces the limit value n of the current estimation range by “1” (step b10). Thereafter, this process is terminated. If it is determined that the counter C _d is less than the counter threshold C _thd (step b9: no), this process is terminated.

According to the implementation example of FIG. 6, in particular, the case where the estimated range is exceeded for a short time by providing the counters C _e and C _d can be excluded from the conditions for changing the estimated range. Specifically, the estimation range changing means 26 is configured by a hardware function or a software function on a processor (not shown) capable of performing the same operation as described above and outputting the result using the above-described implementation model. Has been.

According to the electric brake device DB described above, the A / D converter 17b of the brake force estimating means 17 is a variable type that makes the estimated range of the estimated brake force variable by an external input. In the case where the normal range and the non-normal region in the estimated braking force can be assumed to some extent as in the case of DB, for example, the estimation range is set to the normal range, and the estimation range is expanded as necessary by the estimation range changing means 26. This makes it easy to achieve the necessary resolution for each estimated range of the estimated braking force. Therefore, it is possible to improve the control accuracy in the normal range without configuring a highly accurate load sensor as in the prior art.

Other embodiments will be described. In the following description, the same reference numerals are assigned to the portions corresponding to the matters described in the preceding forms in each embodiment, 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. 2, rotor angular speed estimation means 28 for estimating the rotational angular speed of a brake rotor (not shown) may be provided, and temperature estimation means 29 may be provided in the control device 2. The temperature estimation means 29 estimates the temperature of the brake rotor 8 (FIG. 1) or the friction member 9 (FIG. 1) from the rotational angular speed estimated by the rotor angular speed estimation means 28. In the configuration in which the rotor angular velocity estimation means 28 and the temperature estimation means 29 are provided, the estimation range changing means 26 sets the limit value of the estimation range when the temperature estimated by the temperature estimation means 29 is equal to or higher than a predetermined temperature. It expands from the limit value before the change.

The estimated range changing unit 26 changes the limit value of the estimated range to be smaller than the limit value before the change when the temperature estimated by the temperature estimating unit 29 becomes lower than a predetermined temperature. The determined temperature is determined by a result of a test, simulation, or the like, and is stored in the recording unit 27 so as to be rewritable. When the friction member 9 (FIG. 1) is pressed against the brake rotor 8 (FIG. 1), the friction coefficient between the friction member 9 (FIG. 1) and the brake rotor 8 (FIG. 1) varies depending on the temperature. Then, the limit value of the estimated range is changed based on the heat generated by pressing the friction member 9 (FIG. 1) against the brake rotor 8 (FIG. 1).

FIG. 7 is a flowchart showing an example in which the estimated range of the estimated braking force is changed based on the calorific value of each wheel estimated from the braking force and the vehicle speed in a vehicle equipped with this electric brake device. After the start of this processing, the temperature estimation means 29 (FIG. 2) calculates the vehicle speed v (k) at the discretization time t = k based on the rotational angular speed estimated by the rotor angular speed estimation means 28 (FIG. 2). From this vehicle speed, a heat flow rate (change amount) Δ⌒J generated by the brake is estimated (step c1). In this specification, the symbol “⌒” at the beginning of the code indicates an estimated value, but the symbol “⌒” may be omitted. Further, in FIG. 7, “⌒” is added on other symbols.

Next, the temperature estimation means 29 estimates a roughly generated heat flow rate Δ⌒J _xx of each wheel (step c2). The generated heat flow rate Δ⌒J _xx is obtained by multiplying the value obtained by dividing the brake force F _bxx of each wheel by the total brake force F _ball by the heat flow rate Δ⌒J estimated in step c1. Thereafter, the temperature estimation means 29 estimates the temperature ⌒T (k) of the friction member 9 (FIG. 1) from the generated heat flow rate Δ⌒J _{xx for} each wheel (step c3).

Then, the estimated range changing means 26, on the basis of the estimated temperature ⌒T (k), is changed to increase or decrease the estimation range R _n (step c4). In this case, the estimated range R _n is, FIG. 5 described above using a threshold, a counter for estimated temperature can be changed by the processing shown in FIG 6. Thereafter, this process is terminated. Note that the temperature センサ T (k) may be estimated by providing a temperature sensor such as a thermistor separately in the electric brake device.

As described above, the rough heat generation amount of each wheel is estimated from the braking force and the vehicle speed, and the estimation range is changed based on the heat generation amount. At this time, the change of the estimation range based on the heat generation is for the purpose of dealing with the fluctuation of the friction coefficient of the friction member 9 (FIG. 1), and the estimated braking force is estimated to be affected by the friction coefficient such as a brake load. An example is shown. According to this configuration, it is possible to finely change the limit value of the estimation range corresponding to the variation of the friction coefficient of the friction member 9 (FIG. 1) and the brake rotor 8 (FIG. 1).

As shown in FIG. 2, the brake force estimation means 17 is estimated by the rotation angle estimation means 24 within a predetermined time after the limit value of the estimated brake force estimation range is changed by the estimation range change means 26. The estimated braking force may be obtained based on a predetermined relationship between the rotation angle and the braking force. The predetermined time is determined by the result of the test or simulation, and is stored in the recording means 27 so as to be rewritable.

FIG. 8 is a flowchart showing an example in which the electric motor 4 (FIG. 1) is controlled without using the brake force estimation result within a predetermined time after changing the limit value of the estimated range of the estimated brake force. . In this example, for example, when a time for changing the estimated range of the braking force is required, such as a rewrite time of a register of a sensor element (not shown), the predetermined time after the estimated range is changed is the braking force. An example is shown in which the electric brake device is controlled without using the estimation result. For example, if the relationship between the rotation angle of the electric motor 4 (FIG. 1) and the braking force is measured to some extent in advance, rough control is possible although the control accuracy is reduced, and the predetermined time is a short time. If there is, there is no problem in practical use.

As shown in FIG. 8, after the start of this process, after the estimated range of the estimated braking force is changed by the estimated range changing means 26 (FIG. 2) (step d1), the braking force estimating means 17 (FIG. 2) It is determined whether or not the estimation range R (k) in the sample k (at the discretization time t = k) is the same as the estimation range R (k−1) in the previous sample (k−1) (step d2). In determining that it is identical (Step d2: yes), the braking force estimating means 17 (FIG. 2) performs the update subtracting "1" from the counter _{C id} (Step d3). Thereafter, the process proceeds to step d5.

When it is determined that the estimated range in the sample k is not the same as the estimated range in the previous sample (k−1) (step d2: no), the brake force estimating means 17 (FIG. 2) determines the value of the counter _Cid . _Is a predetermined time C _upd after the estimated range is changed (step d4). Thereafter, the process proceeds to step d5. In step d5, the brake force estimating means 17 determines whether or not the value of the counter _Cid is “0” or more.

When it is determined that the value of the counter C _id is equal to or greater than “0” (step d5: yes), the brake force estimation means 17 (FIG. 2) sets the target motor angle θ _r to the target value r, and the motor angle θ Is set to the control amount y (step d6). Thereafter, the process proceeds to step d9. When it is determined that the value of the counter C _id is less than “0” (step d5: no), the brake force estimating means 17 (FIG. 2) resets the counter C _id to “0” (step d7). Then, we set the target braking force F _r to the target value r, setting the estimated braking force Fb on the controlled variable y (step d8). In step d9, a control calculation is executed, and then this process is terminated.

FIG. 9 is a diagram showing a change in the estimated range according to a change in the braking force when the operation of any of FIGS. 5 to 8 is implemented. By changing the limit value of the estimated range of the estimated brake force by the estimated range changing unit 26 (FIG. 2), it is easy to configure the brake force estimating unit 17 having sufficient resolution in the normal range of the electric brake device. Thus, control accuracy can be improved and costs can be reduced. In addition, by sequentially updating the so-called detection range of the brake force estimating means 17, it is possible to avoid a situation where it becomes difficult to control the electric brake device that would cause the range to be over. When the target braking force is used as the braking force, it is preferable because the estimated range can be changed quickly, but the estimated braking force can also be used. Alternatively, both of the above may be used.

As shown in FIG. 10, as still another embodiment, the brake force estimating means 17 is a digital signal obtained by A / D converting the rotation angle formed by the analog signal estimated by the rotation angle estimating means 24 with an A / D converter 17b. The relationship between the signal and the braking force is obtained in advance by testing or simulation and stored in the relationship setting means 17c, and the estimated braking force is calculated based on the relationship between the rotation angle from the rotation angle estimating means 24 and the target braking force. You may ask. Although not shown, the relationship between the motor current from the current detection means 22 (FIG. 2) and the target brake force is stored in the relationship setting means 17c in the same manner as described above, and based on these motor current and target brake force. The estimated braking force may be obtained.

As mentioned above, although the suitable form for implementing this invention based on embodiment was demonstrated referring drawings, embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is shown not by the above description but by the claims. Those skilled in the art will readily appreciate various changes and modifications within the obvious scope upon reviewing this specification. Therefore, such changes and modifications should be construed as being within the scope of the invention defined by the claims or within the scope equivalent thereto.

2 ... Control device 4 ... Electric motor 6 ... Linear motion mechanism (friction member operation means)
DESCRIPTION OF SYMBOLS 8 ... Brake rotor 9 ... Friction member 17 ... Brake force estimation means 24 ... Rotation angle estimation means 26 ... Estimation range change means 28 ... Rotor angular velocity estimation means 29 ... Temperature estimation means DB ... Electric brake device

Claims

A brake rotor, a friction member to be brought into contact with the brake rotor, a friction member operation means for bringing the friction member into contact with the brake rotor, an electric motor for driving the friction member operation means, and the friction member to the brake rotor Electric brake device comprising: brake force estimating means for obtaining an estimated brake force that is an estimated value of a brake force generated by pressing; and a control device that controls the electric motor to control the estimated brake force following the target brake force. Because
The control device includes an electric range change unit that changes a limit value of an estimated range of the estimated brake force by the brake force estimation unit based on one or both of the target brake force and the estimated brake force. Brake device.
The electric brake device according to claim 1, wherein the estimation range changing means includes the following condition group:
When one or both of the target braking force and the estimated braking force exceed a threshold value in the estimated range,
When the absolute value of the deviation between the threshold value in the estimated range and the one or both of the braking forces is within a predetermined value and the amount of change in either or both of the braking forces is greater than or equal to a predetermined value, and either When the excess time when one or both braking forces exceed the threshold exceeds a predetermined time,
The electric brake device that changes the limit value of the estimated range to be larger than the limit value before the change based on at least one of the conditions.
The electric brake device according to claim 1 or 2, wherein the estimated range changing means includes the following condition group:
When one or both of the target braking force and the estimated braking force falls below a threshold value in the estimated range,
When the absolute value of the deviation between the threshold value in the estimated range and the one or both of the braking forces is within a predetermined value and the amount of change in the braking force of either one or both is less than or equal to the predetermined value; When the time during which one or both braking forces are below the threshold exceeds a predetermined time,
An electric brake device that changes the limit value of the estimated range to be smaller than the limit value before the change based on a condition including at least one of them.
4. The electric brake device according to claim 1, further comprising: a rotation angle estimation unit that estimates a rotation angle of the electric motor, wherein the brake force estimation unit is configured to perform the estimation range change unit by the estimation range change unit. After changing the limit value of the estimated range of the estimated brake force, the estimated brake force is determined based on the determined relationship between the rotation angle and the brake force estimated by the rotation angle estimating means within a determined time. Electric brake device that demands power.
5. The electric brake device according to claim 1, wherein the brake force estimating unit includes a load sensor that estimates a pressing force when the friction member presses the brake rotor. 6. apparatus.
The electric brake device according to any one of claims 1 to 5, further comprising a rotor angular velocity estimating means for estimating a rotational angular velocity of the brake rotor,
The controller is provided with temperature estimating means for estimating the temperature of the brake rotor from the rotational angular speed estimated by the rotor angular speed estimating means,
The estimated range changing means expands the limit value of the estimated range from the limit value before the change when the temperature estimated by the temperature estimating means is equal to or higher than a predetermined temperature, and is estimated by the temperature estimating means An electric brake device that changes a limit value of the estimated range to be smaller than a limit value before the change when the temperature becomes lower than a predetermined temperature.