Electric brake device

Abstract

The brake mechanism presses the brake pad toward the brake disc by the driving of the electric motor. An ECU for an electric brake estimates a contact position of a brake pad and a brake disc on the basis of a brake characteristic (e.g., a relationship between a motor current and a motor position of an electric motor). An ECU for an electric brake estimates a contact position and / or rigidity using, as a reference (zero), a motor current at a position returning to a prescribed value from a motor position when the motor current reaches a prescribed current due to contact between a brake pad and a brake disc.

Description

Technical Field

[0001] This invention relates to an electric braking device for applying braking force to vehicles such as automobiles. Background Technology

[0002] Patent document 1 describes an electric disc brake that infers the contact position of the brake pad (the contact position between the brake pad and the brake disc) based on the current value of the electric motor (motor current).

[0003] Existing technical documents

[0004] Patent Document 1: Japanese Patent Application Publication No. 2010-83282 Summary of the Invention

[0005] The technical problem that the invention aims to solve

[0006] The technology described in Patent Document 1 improves the accuracy of inferring the contact position of the bushing by subtracting (removing) the noise (pulsation) of one revolution of the electric motor in the gap region from the measured relationship between the motor position and the motor current (braking characteristics). However, in this case, it is impossible to remove the noise (pulsation) of more than one revolution of the electric motor.

[0007] One of the objectives of this invention is to provide an electric braking device that can improve the accuracy of contact position estimation and rigidity estimation.

[0008] Technical solutions for solving technical problems

[0009] An electric braking device according to one embodiment of the present invention includes: an actuator that presses a braking member toward a braked member by driving an electric motor; and a contact position inference unit that infers the contact position between the braking member and the braked member based on the braking characteristics of the electric braking device. When the contact position inference unit causes a physical quantity corresponding to the magnitude of the braking force of the actuator to reach a predetermined physical quantity through the contact between the braking member and the braked member, the actuator position returns to a predetermined value from the current actuator position, and the contact position is inferred based on the physical quantity at the actuator position that has returned to the predetermined value.

[0010] Furthermore, an electric braking device according to one embodiment of the present invention includes: an actuator that presses a braking member toward a braked member by driving an electric motor; and a rigidity estimation unit that estimates the rigidity of the braking member, the braked member, and the actuator based on the braking characteristics of the electric braking device. When the contact between the braking member and the braked member causes a physical quantity corresponding to the magnitude of the braking force of the actuator to reach a predetermined physical quantity, the rigidity estimation unit causes the actuator position to return to a predetermined value from the current actuator position, and estimates the rigidity based on the physical quantity at the actuator position that has returned to the predetermined value.

[0011] According to one embodiment of the present invention, the accuracy of contact position estimation and rigidity estimation can be improved. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of a vehicle equipped with an electric braking device according to an embodiment.

[0013] Figure 2 It means Figure 1 A three-dimensional diagram of the electric braking device.

[0014] Figure 3 It means Figure 1 A cross-sectional view of the electric braking device in the diagram.

[0015] Figure 4 This is a flowchart illustrating the process of offsetting the reference value of the braking characteristics.

[0016] Figure 5 It includes the addition of processing to update the specified value of the returned quantity. Figure 4 The same flowchart (variant example).

[0017] Figure 6 This is a characteristic curve diagram representing one example of braking characteristics (20 in total, including 4 types of low-frequency pulsations and 5 types of rigidity).

[0018] Figure 7 It is Figure 6 The characteristic line diagram represented by part A in the diagram is only magnified (about 10 times) in the vertical direction.

[0019] Figure 8 This is a characteristic curve diagram representing the braking characteristics of the comparative examples (20 in total, including 4 types of low-frequency pulsations and 5 types of rigidity).

[0020] Figure 9 This indicates the braking characteristics of the implementation method (making...) Figure 8 The characteristic curve of the braking characteristics of the comparative example (braking characteristics of the deviated braking characteristics).

[0021] Figure 10It is an explanatory diagram (characteristic line diagram) illustrating how braking characteristics change (forward movement) as the brake pads wear.

[0022] Figure 11 It means through Figure 4 Explanation diagram (characteristic line diagram) of braking characteristics (C1, C2) obtained from processing S3 to S6.

[0023] Figure 12 This indicates that it is performed on memory. Figure 4 Explanation diagram (characteristic line diagram) of the braking characteristics (C1, C2) obtained during the processing of S4 to S6. Detailed Implementation

[0024] The following description uses the example of mounting the electric braking device of the embodiment on a four-wheeled vehicle, with reference to the accompanying drawings. Furthermore, Figure 4 and Figure 5 Each step in the flowchart shown is marked with a symbol such as "S" (e.g., step 1 = "S1"). Additionally, in Figure 1 In the diagram, lines with two diagonal lines represent electrical system lines. Additionally, the subscript "L" corresponds to "left," and the subscript "R" corresponds to "right."

[0025] Figure 1 Indicates the vehicle system. In Figure 1 In the vehicle 1, a braking system 4 is installed to apply braking force to the wheels 2 and 3 (front wheels 2L and 2R, rear wheels 3L and 3R) to brake the vehicle 1. The braking system 4 includes: left and right front wheel electric braking devices 5L and 5R (front braking devices) corresponding to the left front wheel 2L (left front wheel 2L) and the right front wheel 2R (right front wheel 2R); left and right rear wheel electric braking devices 6L and 6R (rear braking devices) corresponding to the left rear wheel 3L (left rear wheel 3L) and the right rear wheel 3R (right rear wheel 3R); a brake pedal 7 (operating component) as a braking operation component; a pedal reaction force device 8 (hereinafter referred to as pedal simulator 8) that generates a recoil reaction force according to the operation (depression) of the brake pedal 7; and a pedal travel sensor 9 as an operation detection sensor that measures the amount of operation of the driver (driver) on the brake pedal 7.

[0026] The left and right front wheel-side electric brake devices 5L and 5R and the left and right rear wheel-side electric brake devices 6L and 6R (hereinafter also referred to as electric brake devices 5 and 6) are configured, for example, as electric disc brakes. The electric brake devices 5 and 6 apply braking force to the wheels 2 and 3 (front wheels 2L and 2R, rear wheels 3L and 3R) by being driven by an electric motor 26. Additionally, for example, the left and right rear wheel-side electric brake devices 6L and 6R are equipped with a parking mechanism (not shown).

[0027] The pedal travel sensor 9 is installed, for example, in the pedal simulator 8. Alternatively, the pedal travel sensor 9 can also be installed in the brake pedal 7. Alternatively, a force sensor that measures the pedal force corresponding to the amount of operation of the brake pedal 7 can be used instead of the pedal travel sensor 9. The pedal travel sensor 9 is connected to the first brake control ECU 10 and the second brake control ECU 11, which are ECUs used for brake control.

[0028] A first brake control ECU 10 (also referred to as the first ECU 10) and a second brake control ECU 11 (also referred to as the second ECU 11) are installed in vehicle 1. The first ECU 10 and the second ECU 11 are configured as a microcomputer including a processing unit (CPU), a storage unit (memory), a control board, etc. The first ECU 10 and the second ECU 11 receive input signals from the pedal travel sensor 9 and perform calculations on the braking force (target braking force) for each wheel (four wheels) through a pre-determined control program.

[0029] For example, the first ECU 10 calculates the target braking force that should be applied to the left front wheel 2L and the right rear wheel 3R. Based on the calculated target braking force, the first ECU 10 outputs (sends) the braking commands (control commands) for the left front wheel 2L and the right rear wheel 3R respectively to the electric brake ECUs 31 and 31 via CAN12 (Controller Area Network), which serves as the vehicle data bus.

[0030] The second ECU 11, for example, calculates the target braking force that should be applied by the right front wheel 2R and the left rear wheel 3L. Based on the calculated target braking force, the second ECU 11 outputs (sends) the braking commands (control commands) for the right front wheel 2R and the left rear wheel 3L respectively via CAN 12 to the electric brake ECUs 31 and 31.

[0031] To perform such braking-related control, the first ECU 10 and the second ECU 11 have control units 10A and 11A that perform calculations based on input information (e.g., signals from the pedal travel sensor 9) and output the calculation results (e.g., control commands corresponding to the target thrust). The first ECU 10 and the second ECU 11 receive vehicle information transmitted via CAN 12 from other ECUs mounted on the vehicle 1 (e.g., prime mover ECU, transmission ECU, steering ECU, autonomous driving ECU, etc., not shown).

[0032] For example, the first ECU10 and the second ECU11 can obtain various vehicle information via CAN12, such as the position of AT gear or MT gear, ignition on / off information, engine speed information, powertrain torque information, transmission gear ratio information, steering wheel operation information, clutch operation information, accelerator operation information, vehicle-to-vehicle communication information, information about the vehicle's surroundings provided by the onboard camera, and information from the acceleration sensor (front and rear acceleration and lateral acceleration).

[0033] A parking brake switch 13 is located near the driver's seat. The parking brake switch 13 is connected to the first ECU 10 (and via CAN 12 to the second ECU 11). The parking brake switch 13 transmits a signal (action request signal) corresponding to the driver's operation instruction for the parking brake's actuation request (a force application request for holding, a release request for releasing) to the first ECU 10 and the second ECU 11. Based on the operation of the parking brake switch 13 (action request signal), the first ECU 10 and the second ECU 11 send parking brake commands for each of the two rear wheels (rear wheels 3L and 3R) to the electric brake ECUs 31 and 32. The parking brake switch 13 is equivalent to a switch that actuates the parking mechanism.

[0034] Figure 2 and Figure 3 Electric braking devices 5 and 6 are indicated. Electric braking devices 5 and 6 include a braking mechanism 21 constituting an actuator, an electric motor 26, and an ECU 31 for electric braking. Electric braking devices 5 and 6 apply braking force to the vehicle 1 by performing position control and thrust control of the braking mechanism 21. Therefore, the braking mechanism 21 includes: a rotation angle sensor 32, which serves as a position detection unit for detecting the rotational position of the motor. Figure 3 ); thrust sensor 33, which is a thrust detection unit for detecting the thrust (piston thrust) generated in piston 24. Figure 3 ); current sensor 34 is a current detection unit that detects the current (motor current) of electric motor 26.

[0035] The braking mechanism 21 includes, for example, a bracket 22, a caliper 23 as a cylinder (wheel cylinder), a piston 24 as a pressing member, and a brake pad 25 as a braking member (friction pad). An electric motor 26 is provided in the braking mechanism 21 to drive it, that is, to generate braking force. Additionally, the braking mechanism 21 includes a reduction mechanism 27, a rotary-to-linear conversion mechanism 28, and a return spring 29 that serves as a fault-clearing mechanism. The reduction mechanism 27 and the ECU board 31B of the electric brake ECU 31 are covered by a housing 30. The housing 30, the reduction mechanism 27, the electric motor 26, the rotation angle sensor 32, and the ECU board 31B constitute the drive components for driving the braking mechanism 21.

[0036] The bracket 22 is fixed to the side of the vehicle body 1. The caliper 23 is supported (floating support) on the bracket 22 in a manner that allows axial movement of the brake disc D. The electric motor 26 rotates by a power supply, pushing the piston 24. Thus, the electric motor 26 applies braking force. The electric motor 26 is controlled by the electric brake ECU 31 based on braking commands (control commands) from the first ECU 10 or the second ECU 11. The reduction mechanism 27, for example, is a gear reduction mechanism that reduces the rotation of the electric motor 26 and transmits it to the rotary-to-direct-drive conversion mechanism 28.

[0037] The rotary-to-linear conversion mechanism 28 converts the rotation of the electric motor 26, transmitted via the reduction mechanism 27, into axial displacement (linear displacement) of the piston 24. The piston 24 is propelled by the electric motor 26, causing the brake pads 25 to move. The brake pads 25 are pressed against the brake disc D by the piston 24. A pair of brake pads 25 are located on opposite sides of the brake disc D along its axial direction and are supported by brackets 22. The brake disc D, as the braked component (rotor), rotates together with the wheels 2L, 2R, 3L, and 3R.

[0038] When braking is applied, the return spring 29 applies a rotational force in the direction of brake release to the rotating component of the rotary-to-direction switching mechanism 28. The braking mechanism 21 pushes the piston 24 to press the brake pad 25 against the brake disc D via the drive of the electric motor 26. That is, based on a braking request (braking command), the braking mechanism 21 transmits the thrust generated by the drive of the electric motor 26 to the piston 24 that moves the brake pad 25. Thus, the braking mechanism 21 presses the brake pad 25 against the brake disc D.

[0039] like Figure 1 As shown, the ECU 31 for the electric brake is provided correspondingly to each braking mechanism 21. The ECU 31 for the electric brake is configured, for example, to include a microcomputer having a processing unit (CPU), a storage device (memory), a control board, etc., and a drive circuit (e.g., an inverter) for supplying power to the electric motor 26. Figure 3 As shown, the ECU 31 for electric brakes includes an ECU board 31B on which computing circuitry and the like are mounted. The ECU 31 for electric brakes controls the electric motor 26 that actuates the braking mechanism 21 based on commands from the first ECU 10 or the second ECU 11.

[0040] The electric brake ECU 31 includes a control unit 31A (in other words, an ECU board 31B). This control unit 31A performs calculations based on input information (e.g., signals corresponding to control commands) and outputs the calculation results (e.g., electric motor drive commands corresponding to the control commands). The electric brake ECU 31, together with the first ECU 10 and the second ECU 11, constitutes a control device (brake control device) for controlling the electric motor 26. In this case, the electric brake ECU 31 controls the drive of the electric motor 26 based on the braking command (control command) input to the electric brake ECU 31. Additionally, the rear wheel-side electric brake ECU 31 controls the drive (applying force, releasing force) of the parking mechanism based on the parking action command input to it. Signals corresponding to the braking command and signals corresponding to the parking action command are input from the first ECU 10 or the second ECU 11 to the electric brake ECU 31.

[0041] The rotation angle sensor 32 detects the rotation angle (motor rotation angle) of the rotation shaft 26A of the electric motor 26. The rotation angle sensor 32 is respectively provided with the electric motor 26 of each braking mechanism 21, forming a position detection unit that detects the rotational position (motor rotation position) of the electric motor 26 and, consequently, the position (piston position) of the piston 24. The rotation angle sensor 32 is, for example, composed of a magnet component, i.e., a magnet 32A, mounted on the rotation shaft 26A of the electric motor 26, and a magnet signal receiving unit, i.e., a magnetic detection IC chip 32B, provided on the electric brake ECU 31 (ECU board 31B). The electric brake ECU 31 (ECU board 31B) can calculate and detect the rotation angle of the rotation shaft 26A of the electric motor 26 by detecting the change in magnetic flux of the rotating magnet 32A using the magnetic detection IC chip 32B.

[0042] The thrust sensor 33 detects the reaction force relative to the thrust (pressing force) from the piston 24 to the brake pad 25. The thrust sensors 33 are respectively installed in each braking mechanism 21, forming a thrust detection unit for detecting the thrust (piston thrust) generated by the piston 24. The thrust sensor 33 is installed in the rotary-to-direction conversion mechanism 28. The current sensor 34 detects the current (motor current) supplied to the electric motor 26. The current sensor 34 is respectively installed corresponding to the electric motor 26 of each braking mechanism 21, forming a current detection unit for detecting the current (motor current, motor torque current) supplied to the electric motor 26. The rotation angle sensor 32, the thrust sensor 33, and the current sensor 34 are connected to the electric brake via the ECU 31.

[0043] The electric brake ECU 31 (and the first ECU 10 and the second ECU 11 connected to it via CAN 12) can acquire the rotation angle of the electric motor 26 based on a signal from the rotation angle sensor 32. The electric brake ECU 31 (and the first ECU 10 and the second ECU 11) can acquire the thrust generated by the piston 24 based on a signal from the thrust sensor 33. The electric brake ECU 31 (and the first ECU 10 and the second ECU 11) can acquire the motor current supplied to the electric motor 26 based on a signal from the current sensor 34.

[0044] Next, the braking application and release operations based on the electric braking devices 5 and 6 will be explained. Furthermore, the following explanation will use the operation of the brake pedal 7 by the driver as an example. However, for the case of the automatic brake, for example, the operation is largely the same, except that the automatic brake command is output from the automatic driving ECU, the automatic braking ECU, the first ECU 10, or the second ECU 11 to the electric brake ECU 31.

[0045] For example, when the driver depresses the brake pedal 7 while the vehicle 1 is in motion, the first ECU 10 and the second ECU 11 output commands (control commands corresponding to the target thrust command value) to the electric brake ECU 31 based on the detection signal input from the pedal travel sensor 9. Based on the commands from the first ECU 10 and the second ECU 11, the electric brake ECU 31 drives (rotates) the electric motor 26 in the positive direction, i.e., the direction of braking. The rotation of the electric motor 26 is transmitted to the rotary-to-direction conversion mechanism 28 via the reduction mechanism 27, and the piston 24 advances towards the brake pad 25.

[0046] Therefore, the brake pad 25 is pressed against the brake disc D, and braking force is applied. At this time, based on the detection signals from the pedal travel sensor 9, the rotation angle sensor 32, the thrust sensor 33, etc., the drive of the electric motor 26 is controlled, thereby establishing the braking state. In such braking, a force in the brake release direction is applied to the rotating component 28A of the rotary direct-acting conversion mechanism 28 and the rotating shaft 26A of the electric motor 26 by the return spring 29 provided in the brake mechanism 21.

[0047] On the other hand, if the brake pedal 7 is operated towards the release side, the first ECU 10 and the second ECU 11 output a command corresponding to the operation (a control command corresponding to the target thrust command value) to the electric brake ECU 31. Based on the command from the first ECU 10 and the second ECU 11, the electric brake ECU 31 drives (rotates) the electric motor 26 in the opposite direction, i.e., the direction of brake release. The rotation of the electric motor 26 is transmitted to the rotary direct-acting conversion mechanism 28 via the reduction mechanism 27, and the piston 24 retracts away from the brake pad 25. Furthermore, when the brake pedal 7 is completely released, the brake pad 25 separates from the brake disc D, releasing the braking force. In this non-braking state where the brake is released, the return spring 29 provided in the brake mechanism 21 returns to its initial state.

[0048] Next, the thrust control and position control based on electric braking devices 5 and 6 will be explained.

[0049] The first ECU 10 and the second ECU 11 calculate the braking force to be generated by the electric braking devices 5 and 6, i.e., the target thrust generated by the piston 24, based on detection data from various sensors (e.g., pedal travel sensor 9) and automatic braking commands. The first ECU 10 and the second ECU 11 output braking commands (control commands) corresponding to the target thrust to the electric brake ECU 31. The electric brake ECU 31 performs thrust control on the electric motor 26 in a manner that the piston 24 generates the target thrust, using the piston thrust detected by the thrust sensor 33 as feedback, and position control using the motor rotation position detected by the rotation angle sensor 32 as feedback.

[0050] That is, the braking mechanism 21 adjusts the thrust of the piston 24 based on the braking command (target thrust) from the first ECU 10 and the second ECU 11 and the feedback signal from the thrust sensor 33 that measures the thrust of the piston 24. To determine the thrust, torque control is performed on the electric motor 26 via the rotary direct-drive conversion mechanism 28 and the reduction mechanism 27, that is, current control is performed based on the feedback signal from the current sensor 34 that measures the amount of current supplied to the electric motor 26. There is a correlation between the braking force, the piston thrust (thrust), the torque of the electric motor 26 (motor torque), the current value, and the piston position (based on the tachometer measurement of the electric motor 26 by the rotation angle sensor 32).

[0051] The braking force of the electric braking devices 5 and 6 is generated by pressing the brake pads 25 against the brake disc D. At this time, the driver's braking request is detected by the pedal travel sensor 9. The driver's braking request detected by the pedal travel sensor 9 is input as a braking command from the first ECU 10 and the second ECU 11 to the electric brake ECU 31 (ECU board 31B). The electric brake ECU 31 (ECU board 31B) controls the electric motor 26 based on the braking command corresponding to the driver's request and the signal from the thrust sensor 33 (the signal corresponding to the thrust).

[0052] The torque generated by the electric motor 26 is amplified by the reduction mechanism 27 and converted into thrust, i.e., axial thrust of the piston 24, through the rotary direct-drive conversion mechanism 28. The brake pad 25 is pressed against the brake disc D by the piston 24. Furthermore, the electric motor 26 is controlled by detecting the rotation angle of the rotating shaft 26A, which becomes the rotation angle of the electric motor 26, using the rotation angle sensor 32. That is, the electric motor 26 is controlled by detecting changes in the magnetic flux of the magnet 32A, which rotates together with the rotating shaft 26A, using the magnetic detection IC chip 32B, which serves as a magnet signal receiver. At this time, by controlling the position of the piston 24 using the rotation angle of the electric motor 26 detected by the rotation angle sensor 32, the gap between the brake pad 25 and the brake disc D can be adjusted.

[0053] However, to control electric braking devices with high precision, it is necessary to accurately infer the contact position between the braking component and the braked component. Furthermore, the rigidity of the braking component, the braked component, and the actuator (braking mechanism, electric motor) also needs to be accurately inferred based on the thrust sensor specifications or for control without a thrust sensor (thrust sensor-free control). That is, contact position is required for high-precision control of the liner gap, and rigidity is required for high-precision control of the braking force (thrust) (more specifically, for high-precision thrust control without a thrust sensor). Therefore, to control electric braking devices with high precision, it is necessary to accurately infer the contact position and / or rigidity. However, when noise (pulsation) enters the sensor values ​​of the controlled object, the accuracy of the contact position inference and the accuracy of the rigidity inference decrease.

[0054] Therefore, in this implementation, a reference position is established by returning from the position where the specified motor current is reached to a position with a certain gap. Then, based on the braking characteristics (the relationship between piston position or motor position and piston thrust or motor current) that cause the motor current at this reference position to deflect to zero (0), the contact position and rigidity are inferred. Therefore, the influence of low-frequency pulsation can be reduced, and the accuracy of contact position inference and rigidity inference can be improved. As a result, deviations in contact position and rigidity can be reduced, and the gap (clearance) between the braking component and the braked component can be prevented from becoming too small or too large. Consequently, the drag torque between the braking component and the braked component can be reduced, and the responsiveness when applying braking force can be improved. These points will be explained in detail below.

[0055] Figure 6 This indicates the braking characteristics of the electric braking devices 5 and 6. Specifically, it indicates the braking characteristics expressed by the rotational position of the electric motor 26, i.e., the "motor position," and the current value of the electric motor 26, i.e., the "motor current." Figure 6 In this example, 20 characteristics are represented, including 4 types of low-frequency pulsations and 5 types of rigidity. The position where the motor current rises sharply corresponds to the contact position (contact position) between the braking component (brake pad 25) and the braked component (brake disc D). In the gap region prior to the contact position, 4 types of low-frequency pulsations are exhibited, and after the contact position, 5 types of rigidity are superimposed. The "motor position" is detected, for example, by the rotation angle sensor 32, and the "motor current" is detected by the current sensor 34.

[0056] Furthermore, the "motor position" is related to the axial position of piston 24, i.e., the "piston position." Therefore, as a braking characteristic, the "piston position" can be used instead of the "motor position." In this case, the "piston position" can be detected or calculated based on the "motor position." When detecting the "piston position," for example, a displacement sensor that detects the displacement of piston 24 can be provided in the braking mechanism 21. Additionally, the "motor current" is related to the torque of electric motor 26, i.e., the "motor torque," or the thrust of piston 24, i.e., the "piston thrust." Therefore, as a braking characteristic, either "motor torque" or "piston thrust" can be used instead of the "motor current." In this case, either "motor torque" or "piston thrust" can be detected or calculated based on the "motor current." When detecting the "motor torque," for example, a torque sensor that detects the torque of electric motor 26 (rotation shaft 26A) can be provided. When detecting the "piston thrust," it can be detected by a thrust sensor 33.

[0057] In short, such as Figure 6 As shown, the motor current (motor torque, piston thrust) increases sharply upon contact between the brake pad 25 (braking component) and the brake disc D (braked component). Furthermore, the braking characteristics at this time, i.e., the relationship between the "motor position (piston position)" and the "motor current (motor torque, piston thrust)," correspond to the rigidity of the brake pad 25, the brake disc D, and the braking mechanism 21. For example, when the change (increase) in the displacement (advance) of the motor current (motor torque, piston thrust) relative to the motor position (piston position) is large, the rigidity is high; when the change (increase) in the displacement (advance) of the motor current (motor torque, piston thrust) relative to the motor position (piston position) is small, the rigidity is low.

[0058] Figure 7 Will Figure 6 Part A in the diagram is only magnified (e.g., magnified approximately 10 times) in the vertical direction (up-down direction). The contact position where the motor current (motor torque, piston thrust) begins to rise sharply gradually advances due to wear of the brake pads 25 and brake disc D, etc. For example, as... Figure 10 As shown, the contact positions P1, P2, and P3 gradually move to the right in the order of P1→P2→P3 as the brake pad 25 and brake disc D wear. Furthermore, after the contact positions, as shown by multiple characteristic lines, the rigidity of the brake pad 25, brake disc D, and braking mechanism 21 is affected not only by the wear and uneven wear of the brake pad 25 and brake disc D, but also by deviations caused by the temperature and efficiency of the actuators (braking mechanism 21, electric motor 26). Moreover, if low-frequency pulsations caused by the meshing of the gears in the reduction mechanism 27 are applied, then... Figure 6 and Figure 7Similar to the characteristics of "+low-frequency unilateral vibration upper limit side" and "+low-frequency unilateral vibration lower limit side", even with the same rigidity, the motor current (thrust) will deviate by 4 times the amplitude of the pulsation. Therefore, if the contact position and / or rigidity are inferred based on this characteristic, the inference results will also be biased.

[0059] Therefore, in the implementation method, by performing Figure 4 The processing shown will change the braking characteristics from Figure 8 Towards Figure 9 Offset (correction) thereby reducing the impact of low-frequency pulsations. Figure 8 and Figure 9 also with Figure 6 and Figure 7 Similarly, for the same contact location, 20 characteristics were represented, including 4 types of low-frequency pulsation and 5 types of rigidity. Furthermore, as a comparative example, Figure 8 Indicates to proceed Figure 4 The braking characteristics before processing. In contrast, as an implementation method, Figure 9 Indicates by conducting Figure 4 The treatment is used to improve the braking characteristics after deviation. Figure 4 The treatment shown is to make the braking characteristics from Figure 8 Towards Figure 9 Offset (correction) processing. For example... Figure 8 As shown, if point A is defined as the point where the motor current (motor torque, piston thrust) reaches the specified current T (specified torque T, specified thrust T), and point B is defined as the point where the motor returns from point A to the specified amount S, then... Figure 4 In the process shown, the braking characteristics are offset (corrected) by using the motor current (motor torque, piston thrust) at point B as a reference (e.g., zero). Therefore, it is possible to... Figure 8 The braking characteristics are obtained Figure 9 The braking characteristics after offset (correction) (corrected braking characteristics).

[0060] Next, besides Figure 8 and Figure 9 In addition, refer to Figure 11 right Figure 4 The processing shown will be explained. Figure 4 The processing is performed, for example, by the electric brake ECU 31 (control unit 31A). In this case, the electric brake ECU 31 can, for example, start based on a command (offset command) from the first ECU 10 or the second ECU 11. Figure 4 The specific timing for starting the process will be described later.

[0061] In S1, a predetermined value S (piston return S, motor return S) is determined (calculated) in advance. This predetermined value S is stored, for example, in the memory of the ECU 31 for the electric brake. The predetermined value S is the return amount of the electric motor 26 (piston 24) used in the process of S4 described later. The predetermined value S can be stored in the memory in advance (before the use of the electric brake devices 5 and 6) during the manufacturing of vehicle 1, etc., without having to perform the process of S1 every time. The magnitude of the predetermined value S will be described later. In the next S2, the contact position inference and rigidity inference mode are started. That is, the process of shifting the braking characteristics begins. Specifically, in S3, the electric motor 26 is driven in the forward rotation direction, that is, the direction in which the brake pad 25 abuts against the brake disc D (the direction in which braking force is applied). As a result, the piston 24 advances, the brake pad 25 abuts against the brake disc D, and as the brake pad 25 presses (clamps) the brake disc D, the motor current begins to increase. Figure 11 The text represents two characteristics, C1 and C2, namely characteristic C1, which is "+low-frequency unilateral vibration upper limit side", and characteristic C2, which is "+low-frequency unilateral vibration lower limit side".

[0062] In S3, the electric motor 26 is driven in the forward direction until the physical quantities (motor current, piston thrust, motor torque) corresponding to the magnitude of the braking force reach the specified physical quantities T (specified current T, specified thrust T, specified torque T). Figure 8 and Figure 11 Point A corresponds to the point where the specified current T is reached, becoming a specified physical quantity. The magnitude of the specified physical quantities T (specified current T, specified thrust T, specified torque T) will be described later. In the following S4, the specified value S is returned in the X-axis direction from the position where the motor current (piston thrust, motor torque) reaches the specified current T (specified thrust T, specified torque T). That is, the electric motor 26 is stopped at the position corresponding to point A, and then driven from that position in the reverse direction, i.e., the direction in which the brake pad 25 leaves the brake disc D (the direction in which the braking force is released), it returns to the position corresponding to point B. Figure 8 As shown, when the position of point A in the X-axis direction where the motor current (piston thrust, motor torque) reaches the specified current T (specified thrust T, specified torque T) is set as xa, and the position of point B in the X-axis direction is set as xb, xa-S=xb.

[0063] In the next step, S5, the motor current (piston thrust, motor torque) at point B is shifted towards a reference value (e.g., zero). That is, as... Figure 8 and Figure 11As indicated by the middle arrow, the motor current (piston thrust, motor torque) at point B is shifted towards zero. In other words, if the Y-axis value (motor current, piston thrust, motor torque) at point B is set to yb, then yb is set to 0. In the next step, S6, the electric motor 26 is driven again in the forward direction, utilizing the characteristics at this time (i.e., Figure 9 Braking characteristics Figure 11 The contact position and rigidity are inferred from the offset characteristics C1 and C2. That is, in S6, "-yb" is subtracted from the motor current (piston thrust, motor torque) measured (detected) when the electric motor 26 is driven in the forward direction again. Furthermore, the relationship between the motor current (piston thrust, motor torque) and the motor position (piston position) obtained therefrom is set as the corrected (offset) characteristics C1 and C2, and the contact position and rigidity are inferred from these corrected (offset) characteristics C1 and C2. Figure 9 With envoy Figure 8 The braking characteristics in the middle are all offset and then corrected (the corrected braking characteristics).

[0064] Here, the specified value S is set to the maximum displacement amount before reaching a specified physical quantity T, which includes wear of the brake pad 25, uneven wear, tilt of the brake disc D, temperature, efficiency of the braking mechanism 21, pulsation, etc. That is, the specified value S can be calculated based on the maximum displacement amount (motor displacement, piston displacement) before the physical quantity (motor current, piston thrust, motor torque) corresponding to the magnitude of the braking force reaches the specified physical quantity T (specified current T, specified thrust T, specified torque T). The specified physical quantity T includes pulsation, etc., and is set to a value larger than the maximum amplitude of the pulsation of the detected value of the physical quantity caused by the actuator (braking mechanism 21, electric motor 26), or, if the pulsation is a unilateral vibration, a value larger than twice the maximum amplitude. That is, the specified physical quantity T (specified current T, specified thrust T, specified torque T) can be set to a value larger than the maximum amplitude of the pulsation of the detected value of the physical quantity (motor current, piston thrust, motor torque) caused by the actuator (braking mechanism 21, electric motor 26). Furthermore, the specified physical quantity T can also vary according to the temperature of the actuator (brake mechanism 21, electric motor 26), brake pad 25, brake disc D, etc. Therefore, when returning to the specified value S, the gap between the brake pad 25 and the brake disc D can be made to be 0 or more, and the deviation of the physical quantities (motor current, piston thrust, motor torque) corresponding to the magnitude of the braking force at the contact position can be minimized as much as possible.

[0065] also, Figure 4 The processing after S4 can also be performed in the memory of the ECU31 for the electric brake. In this case, such as Figure 12As shown, the electric motor 26 continues to drive directly even when the specified current T, which becomes a specified physical quantity, is reached. Then, the characteristic stored in the memory at this time—the relationship between the motor current (piston thrust, motor torque) and the motor position (piston position)—is shifted in the memory. For example, if the characteristic C1 (thick solid line) is obtained by driving the electric motor 26, the motor current (piston thrust, motor torque) returning from point A to point B (the specified quantity S) is shifted towards 0. Thus, the shifted (corrected) thin solid line characteristic C1 can be obtained in the memory. Similarly, if the characteristic C2 (thick dashed line) is obtained by driving the electric motor 26, the motor current (piston thrust, motor torque) returning from point A to point B (the specified quantity S) is shifted towards 0. Thus, the shifted (corrected) thin dashed line characteristic C2 can be obtained in the memory.

[0066] As described above, in the embodiment, the electric braking devices 5 and 6 include an actuator and a contact position inference unit. The actuator, driven by the electric motor 26, presses the brake pad 25, which becomes a braking component, toward the brake disc D, which becomes a braked component. The actuator corresponds, for example, to the braking mechanism 21 and the electric motor 26. The contact position inference unit infers the contact position between the brake pad 25 and the brake disc D based on the braking characteristics. The contact position inference unit corresponds, for example, to the ECU 31 (control unit 31A) for the electric brake. The contact position inference unit (control unit 31A) returns a predetermined value S from the actuator position (e.g., motor position, piston position) when a predetermined physical quantity T (e.g., predetermined current T, predetermined thrust T, predetermined torque T) is reached through the contact between the brake pad 25 and the brake disc D, corresponding to the magnitude of the braking force of the actuator (braking mechanism 21, electric motor 26). Then, the contact position inference unit (control unit 31A) infers the contact position based on the physical quantity (motor current, piston thrust, motor torque) at the position where the specified value S has been returned (e.g., zero).

[0067] Furthermore, in the embodiment, the electric braking devices 5 and 6 are equipped with a rigidity estimation unit. The rigidity estimation unit estimates the rigidity of the brake pad 25, the brake disc D, and the actuator (brake mechanism 21, electric motor 26) based on the braking characteristics. The rigidity estimation unit corresponds, for example, to the ECU 31 (control unit 31A) for the electric brake. The rigidity estimation unit (control unit 31A) returns a predetermined value S from the actuator position (e.g., motor position, piston position) when the physical quantity (e.g., motor current, piston thrust, motor torque) corresponding to the magnitude of the braking force of the actuator (brake mechanism 21, electric motor 26) reaches a predetermined physical quantity T (e.g., predetermined current T, predetermined thrust T, predetermined torque T) through the contact between the brake pad 25 and the brake disc D. Then, the rigidity estimation unit (control unit 31A) estimates the rigidity based on the physical quantity (motor current, piston thrust, motor torque) at the position where the predetermined value S is returned (e.g., zero).

[0068] The specified physical quantity T (e.g., specified current T, specified thrust T, specified torque T) is set to a value greater than the maximum amplitude of the pulsation of the detected value of the physical quantity (e.g., motor current, piston thrust, motor torque) caused by the actuator (brake mechanism 21, electric motor 26). For example, as Figure 6 and Figure 7 As shown, the specified physical quantities T (specified current T, specified thrust T, specified torque T) are set to a value larger than the maximum amplitude of the "+low-frequency unilateral vibration upper limit side". On the other hand, the specified value S is calculated, for example, based on the maximum displacement (motor displacement, piston displacement) until the physical quantities (motor current, piston thrust, motor torque) corresponding to the magnitude of the braking force reach the specified physical quantity T (specified current T, specified thrust T, specified torque T). For example, as Figure 8 , Figure 11 and Figure 12 As shown, the specified value S can be set to the displacement (motor displacement, piston displacement) of the gap region that can be returned from the position of the physical quantity (motor current, piston thrust, motor torque) to the specified physical quantity T (specified current T, specified thrust T, specified torque T) even when the "+low frequency unilateral vibration lower limit side" is reached.

[0069] Thus, according to the implementation method, such as Figure 8 , Figure 11 as well as Figure 12As shown, the ECU 31 (control unit 31A) for the electric brake uses the motor current at the position where the motor current returns to a specified value S from the position where the motor current reaches a specified current T as a reference (zero) to infer the contact position and / or rigidity. Furthermore, the ECU 31 (control unit 31A) for the electric brake can also use the piston thrust at the position where the piston thrust returns to a specified value S from the position where the piston thrust reaches a specified thrust T as a reference (zero) to infer the contact position and / or rigidity. Additionally, the ECU 31 (control unit 31A) for the electric brake can also use the motor torque at the position where the motor torque returns to a specified value S from the position where the motor torque reaches a specified torque T as a reference (zero) to infer the contact position and / or rigidity.

[0070] In either case, braking characteristics based on the motor current, piston thrust, or motor torque (zero) at the position where the specified value S has been returned can suppress the accompanying braking. Figure 9 The braking characteristics deviated from the low-frequency pulsation braking characteristics shown, and the contact position and / or rigidity are inferred. Therefore, the influence of low-frequency pulsation can be reduced, and the accuracy of the inference of contact position and / or rigidity can be improved. As a result, the deviation of contact position and / or rigidity can be reduced. Moreover, the deviation of contact position can be reduced, thus preventing the gap (clearance) between the brake pad 25 and the brake disc D from becoming too small or too large. As a result, the drag torque between the brake pad 25 and the brake disc D can be reduced, and the responsiveness when applying braking force can be improved. In addition, since the rigidity deviation can be reduced, the braking force can be controlled with high precision, and fine vehicle control can be performed.

[0071] According to the embodiment, the current T is set to a value greater than the maximum amplitude of the pulsation of the detected value of the motor current caused by the braking mechanism 21 (e.g., the maximum amplitude of the "+low-frequency unilateral vibration upper limit side"). Furthermore, the thrust T is set to a value greater than the maximum amplitude of the pulsation of the detected value of the piston thrust caused by the braking mechanism 21 (e.g., the maximum amplitude of the "+low-frequency unilateral vibration upper limit side"). Additionally, the torque T is set to a value greater than the maximum amplitude of the pulsation of the detected value of the motor torque caused by the braking mechanism 21 (e.g., the maximum amplitude of the "+low-frequency unilateral vibration upper limit side"). Therefore, the pulsation of the detected values ​​of the physical quantities (motor current, piston thrust, motor torque) caused by the braking mechanism 21 can be eliminated.

[0072] According to the implementation method, the specified value S is calculated based on the maximum displacement (motor displacement, piston displacement) before the physical quantities (motor current, piston thrust, motor torque) corresponding to the magnitude of the braking force reach a specified physical quantity T (specified current T, specified thrust T, specified torque T). Therefore, the position where the specified value S has returned can be set as the position with a gap (gap region) before the brake pad 25 contacts the brake disc D.

[0073] Here, the thrust sensor 33 can also be omitted. That is, the electric braking devices 5 and 6 can also be configured without the thrust sensor 33. In the case of a structure without the thrust sensor 33, the contact position and rigidity can be inferred based on the braking characteristics of the motor position and motor current, and thus the thrust can be inferred. Moreover, as Figure 9 As shown, the deviation between the motor position and the braking characteristics of the motor current can be suppressed, thus improving the contact position and rigidity, and consequently improving the thrust estimation accuracy. On the other hand, in the case of a structure equipped with thrust sensor 33, depending on factors such as sensor specifications and mounting location, pulsations caused by the rolling of the balls in the thrust bearing and pulsations caused by the meshing of the reducer may sometimes become sensor values. In this case, such as... Figure 9 As shown, it can also suppress the deviation between the braking characteristics of the motor position (or piston position) and the piston thrust.

[0074] In addition, Figure 4 The timing of this processing (the processing that causes a reference shift in braking characteristics) is ideal, for example, when vehicle 1 is stopped and not braking. For instance, it is possible to perform this processing when vehicle 1 is started (when the starter switch is turned on, when the engine is started). Figure 4 The processing (processing that shifts the reference of the braking characteristics). In contrast, this is performed on memory. Figure 4 In the case of S4 and above, the braking can be performed regardless of whether the vehicle 1 is stationary, and can be performed during normal braking. Furthermore, in situations where the vehicle 1 is reliably stopped and braking force is not required, such as during brake pad replacement mode when replacing brake pads 25, the braking can be performed simultaneously via the four-wheel electric brake devices 5 and 6. Figure 4 The process involves shifting the reference value of the braking characteristics. However, it is not preferable to perform this process simultaneously on all four wheels outside of such conditions. Therefore, it is preferable to perform this process when a stop can be ensured, except in situations such as pad replacement mode. For example, the wheels without a parking mechanism (e.g., left front wheel 2L, right front wheel 2R) are braked when parking brake is applied, while the wheels with a parking mechanism (e.g., left rear wheel 3L, right rear wheel 3R) are braked when a stop can be ensured even without braking force from one of the wheels with a parking mechanism.

[0075] In the implementation method, such as Figure 4 As shown, the specified value S always uses a preset value. In contrast, as... Figure 5 As shown, the specified value S can also be updated. Additionally, Figure 5 The processing of S1 to S6 and Figure 4 The processing of S1 to S6 is the same. Then... Figure 5 In S11 of S1, the contact position is learned in advance. That is, in Figure 5In the processing, it is assumed that the contact position has been learned (e.g., contact position inference or detection has been performed at least once at the factory). Then, when the contact position / rigidity inference mode is started in S2, the electric motor 26 is driven in the forward direction (the direction of piston 24) in S3. In S12 following S3, it is determined whether a specified physical quantity T has been reached during the period of advancing a specified value S from the contact position.

[0076] If S12 is "Yes," meaning the specified physical quantity T is reached during the period of advancing the specified value S from the contact position, proceed to S4. Conversely, if S12 is "No," meaning the specified physical quantity T is not reached during the period of advancing the specified value S from the contact position, proceed to S13. In this case, in S13, the displacement amount (motor displacement, piston displacement) that will become the stroke when the specified physical quantity T is reached is updated to a new specified value S. Thus, in Figure 5 In the processing, if it is determined in S12 that the specified physical quantity T has not been reached during the period of advancing the specified physical quantity T from the contact position, in S13, the displacement up to reaching the specified physical quantity T is updated to the new specified value S. In performing such... Figure 5 In the case of such processing, the initial specified value S can be made more than... Figure 4 The specified value S used is small. Therefore, the impact of low-frequency pulsations can be further reduced.

[0077] According to this Figure 5 In the modified example shown, if even after moving the specified value S from the stored contact position, the physical quantities (motor current, piston thrust, motor torque) do not reach the specified physical quantities T (specified current T, specified thrust T, specified torque T), the specified value S is set as the displacement until the physical quantities reach the specified physical quantities. This new specified value is stored as the updated specified value S in the memory of the ECU 31 for the electric brake. Therefore, the initial value of the specified value S, i.e., the specified value S of S1, can be set to a smaller value. Based on this, the specified value S can be updated to an appropriate value. As a result, the influence of low-frequency pulsation can be further reduced.

[0078] In this embodiment, the example described is that the left front wheel electric brake 5L and the right rear wheel electric brake 6R are controlled by the control unit 10A of the first ECU 10, and the right front wheel electric brake 5R and the left rear wheel electric brake 6L are controlled by the control unit 11A of the second ECU 11. However, this is not a limitation. For example, the right front wheel electric brake 5R and the left rear wheel electric brake 6L can also be controlled by the control unit 10A of the first ECU 10, and the left front wheel electric brake 5L and the right rear wheel electric brake 6R can be controlled by the control unit 11A of the second ECU 11.

[0079] In this embodiment, an example is given of a so-called floating caliper type disc brake where the braking mechanism 21 has a piston 24 disposed on the inner side of the caliper 23. However, it is not limited to this, and the braking mechanism may also be a so-called opposed piston type disc brake where the pistons are disposed on the inner and outer sides of the caliper, respectively.

[0080] In this embodiment, the case where the braking mechanism 21 is a disc brake is described as an example. However, it is not limited to this. For example, the braking mechanism may also be a drum brake in which the brake shoes (friction pads) are pressed against a drum rotor (rotor) that rotates together with the wheel.

[0081] In this embodiment, an example is given where all four wheels are equipped with electric brakes that operate via electric motor 26. However, this is not a limitation; for example, the front wheels may be equipped with hydraulic brakes and the rear wheels with electric brakes, or the front wheels may be equipped with electric brakes and the rear wheels with hydraulic brakes.

[0082] In this embodiment, the control unit (ECU) for vehicle braking is described as having a structure comprising a first ECU 10, a second ECU 11, and an electric brake ECU 31. However, it is not limited to this; for example, the first ECU 10 and the second ECU 11 may be constituted by a single ECU, or the first ECU 10, the second ECU 11, and the electric brake ECU 31 may be constituted by a single ECU. Furthermore, the contact position estimation unit and / or the rigidity estimation unit may be provided in the first ECU 10, the second ECU 11, the electric brake ECU 31, or other ECUs. That is, the contact position estimation unit and / or the rigidity estimation unit can be provided in any ECU (control unit, control device) mounted in the vehicle.

[0083] According to the embodiment described above, the contact position estimation unit returns a predetermined value to the actuator position when a physical quantity corresponding to the magnitude of the actuator's braking force reaches a predetermined physical quantity through contact between the braking member and the braked member. The contact position is estimated based on the physical quantity at this position where the predetermined value has been returned. Therefore, the contact position can be estimated based on the braking characteristics based on the physical quantity at the position where the predetermined value has been returned—that is, braking characteristics that suppress deviations in braking characteristics accompanied by low-frequency pulsations. This reduces the influence of low-frequency pulsations and improves the accuracy of contact position estimation. As a result, contact position deviations are reduced, and the gap (clearance) between the braking member and the braked member is prevented from becoming too small or too large. Therefore, the drag torque between the braking member and the braked member is reduced, and the responsiveness when applying braking force is improved.

[0084] According to the embodiment, the rigidity estimation unit returns a predetermined value from the actuator position when the physical quantity corresponding to the magnitude of the actuator's braking force reaches a predetermined physical quantity due to contact between the braking component and the braked component, and infers the rigidity based on the physical quantity at the position after returning to the predetermined value. Therefore, rigidity can be inferred based on the braking characteristics based on the physical quantity at the position after returning to the predetermined value, that is, braking characteristics that suppress deviations in braking characteristics accompanied by low-frequency pulsations. As a result, the influence of low-frequency pulsations can be reduced, and the accuracy of rigidity estimation can be improved. Consequently, rigidity deviation can be reduced, braking force can be controlled with high precision, and thus fine vehicle control can be performed.

[0085] According to the implementation method, the physical quantity is set to a value larger than the maximum amplitude of the pulsation of the detected value of the physical quantity caused by the actuator. Therefore, the pulsation of the detected value of the physical quantity caused by the actuator can be removed.

[0086] According to the implementation method, the specified value is calculated based on the maximum displacement before the physical quantity reaches the specified physical quantity. Therefore, the position where the specified value has returned can be set as the position with a gap (gap region) before the braking component contacts the braked component.

[0087] According to the implementation method, regarding the predetermined value, if the physical quantity does not reach the predetermined physical quantity even after moving the predetermined value from the stored contact position, the displacement amount until the physical quantity reaches the predetermined physical quantity is set as a new predetermined value. Therefore, the initial value of the predetermined value can be set to a smaller value. Based on this, the predetermined value can be updated to an appropriate value. As a result, the influence of low-frequency pulsations can be further reduced.

[0088] Furthermore, the present invention is not limited to the embodiments described above, and includes various modifications. For example, the embodiments described above are detailed embodiments for the purpose of easily understanding and illustrating the present invention, and are not limited to having all the structures described. In addition, a part of the structure of a certain embodiment can be replaced with the structure of another embodiment, and it is also possible to add the structure of another embodiment to the structure of a certain embodiment. Furthermore, regarding a part of the structure of each embodiment, other structures can be added, deleted, or replaced.

[0089] This application claims priority based on Japanese Patent Application No. 2023-110586, filed on July 5, 2023. The entire disclosure of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2023-110586, filed on July 5, 2023, is incorporated herein by reference in its entirety.

[0090] Explanation of reference numerals in the attached figures

[0091] 5: Electric braking device

[0092] 5L: Electric brake on the left front wheel side

[0093] 5R: Electric brake on the right front wheel side

[0094] 6: Electric braking device

[0095] 6L: Electric brake device on the left rear wheel side

[0096] 6R: Electric brake on the right rear wheel side

[0097] 21: Braking mechanism (actuator)

[0098] 25: Brake pads (brake components)

[0099] 26: Electric motor (actuator)

[0100] 31: ECU for electric brakes (contact position estimation unit, rigidity estimation unit)

[0101] D: Brake disc (the component being braked)

Claims

1. An electric braking device, characterized in that, have: An actuator, driven by an electric motor, presses the braking component toward the braked component; The contact position inference unit infers the contact position between the braking component and the braked component based on the braking characteristics of the electric braking device. When the contact position inference unit causes a physical quantity corresponding to the magnitude of the braking force of the actuator to reach a predetermined physical quantity through contact between the braking component and the braked component, it causes the actuator position to return to a predetermined value from this current actuator position. The contact position is inferred based on the physical quantity at the actuator position that has returned the specified value.

2. An electric braking device, characterized in that, have: An actuator, driven by an electric motor, presses the braking component toward the braked component; The rigidity estimation unit infers the rigidity of the braking component, the braked component, and the actuator based on the braking characteristics of the electric braking device. When the rigidity inference unit causes a physical quantity corresponding to the magnitude of the braking force of the actuator to reach a predetermined physical quantity through contact between the braking component and the braked component, it causes the actuator position to return to a predetermined value from this current actuator position. The stiffness is inferred based on the physical quantity at the actuator position that has returned the specified value.

3. The electric braking device according to claim 1 or 2, characterized in that, The specified physical quantity is a value greater than the maximum amplitude of the pulsation of the detected value of the physical quantity caused by the actuator.

4. The electric braking device according to claim 1 or 2, characterized in that, The specified value is calculated based on the maximum displacement up to the point where the physical quantity reaches the specified physical quantity.

5. The electric braking device according to claim 1 or 2, characterized in that, If the physical quantity does not reach the specified physical quantity even when the specified value is moved from the stored contact position, the displacement amount until the physical quantity reaches the specified physical quantity is set as a new specified value in place of the specified value.

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