Electric brake control device, control method, and electric brake device

Abstract

To provide a device and a method for controlling an electric brake, and an electric brake device which can suppress deterioration in estimation accuracy based on a current value of an electric motor.SOLUTION: A brake mechanism 22 includes an electric motor 26, a torsion spring 33, and a ratchet mechanism 34. The ratchet mechanism 34 is configured so that a tip 33 of the torsion spring 33 gets over projections 34A, in a case in which rotational torque acting on the torsion spring 33 exceeds a predetermined value when the electric motor 26 is normally rotated. Control devices 41, 10 for braking detect that the tip 33B of the torsion spring 33 gets over the projections 34B on the basis of reduction of a current value energized to the electric motor 26 with respect to a rotational amount of the electric motor 26, when the electric motor 26 is normally rotated.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a control device and a control method for an electric brake, and an electric brake device. [Background technology]

[0002] Patent Document 1 discloses an electric brake device for vehicles that includes a rotating shaft supported on a case of an energy storage mechanism so as to be rotatable integrally with the output shaft of an electric motor. This electric brake device for vehicles stores elastic energy by elastically deforming a spiral spring inside the energy storage mechanism when the rotating shaft rotates in the forward direction, and when the rotating shaft rotates in the reverse direction, the elastic energy stored in the spiral spring is released to apply a rotational torque for the reverse rotation to the rotating shaft.

[0003] Patent Document 2 discloses a parking brake control device that detects abnormalities. This parking brake control device stores the changes in motor current value in three areas during normal operation: inrush current, no-load current, and current rise, as standard values, and detects abnormalities by comparing these with the current value of the motor current value when the electric parking brake is in use. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-24389 A [Patent Document 2] JP 2014-19235 A Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, a torque limiter, a so-called ratchet mechanism, is provided to prevent the spiral spring from elastically deforming more than necessary. However, in an electric brake device, when the electric motor current value is used to estimate thrust, the ratchet riding up may cause the current value to change suddenly, which may deteriorate the thrust estimation accuracy. In Patent Document 2, an abnormality is detected by comparing the current value with a reference value. However, no consideration is given to cases that are not abnormal, such as the ratchet riding up.

[0006] An object of the present invention is to provide an electric brake control device, a control method, and an electric brake device that can suppress deterioration of estimation accuracy based on the current value of an electric motor. [Means for solving the problem]

[0007] One embodiment of the present invention is a control device for an electric brake comprising: an electric motor controlled by a control unit; a torsion spring that stores elastic energy during forward movement, in which the electric motor rotates in the forward direction to move a friction pad in a direction pressing it against a disk, and releases the elastic energy during backward movement, in which the electric motor rotates in the reverse direction to move the friction pad in a direction away from the disk; and a ratchet mechanism having a plurality of engagement portions with which one end of the torsion spring engages, and configured such that if a rotational torque acting on the torsion spring when the electric motor rotates in the forward direction exceeds a predetermined value, the one end of the torsion spring overcomes the engagement portions, and the control unit detects that the one end of the torsion spring has overcome the engagement portions based on a reduction in the value of the current passed through the electric motor relative to the amount of rotation of the electric motor when the electric motor rotates in the forward direction.

[0008] Moreover, one embodiment of the present invention is a control method for an electric brake comprising: an electric motor; a torsion spring that stores elastic energy during forward movement, in which the electric motor rotates in a forward direction to move a friction pad in a direction pressing it against a disk, and releases the elastic energy during backward movement, in which the electric motor rotates in a reverse direction to move the friction pad in a direction away from the disk; and a ratchet mechanism having a plurality of engagement portions with which one end of the torsion spring engages, and configured so that one end of the torsion spring overcomes the engagement portions if a rotational torque acting on the torsion spring exceeds a predetermined value when the electric motor rotates in the forward direction, wherein a control portion that controls the electric motor detects that one end of the torsion spring has overcome the engagement portions based on a reduction in the value of current passed through the electric motor relative to the amount of rotation of the electric motor when the electric motor rotates in the forward direction.

[0009] Furthermore, one embodiment of the present invention is an electric brake device comprising: an electric motor; a torsion spring that stores elastic energy during forward movement, in which the electric motor rotates in a forward direction to move a friction pad in a direction pressing it against a disc, and releases the elastic energy during backward movement, in which the electric motor rotates in a reverse direction to move the friction pad in a direction away from the disc; a ratchet mechanism having a plurality of engagement portions with which one end of the torsion spring engages, the ratchet mechanism being configured so that, when a rotational torque acting on the torsion spring exceeds a predetermined value when the electric motor rotates in the forward direction, the one end of the torsion spring overcomes the engagement portions; and a control device that detects that the one end of the torsion spring has overcome the engagement portions based on a reduction in a value of current passed through the electric motor relative to the amount of rotation of the electric motor when the electric motor rotates in the forward direction. Effect of the Invention

[0010] According to the present invention, it is possible to suppress deterioration of the estimation accuracy based on the current value of the electric motor. [Brief description of the drawings]

[0011] [Figure 1]1 is a schematic diagram showing a system configuration of a vehicle equipped with an electric brake device according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view of the electric brake in FIG. [Diagram 3] 3 is an explanatory diagram of a speed reduction mechanism and a fail-open mechanism of the electric brake in FIG. 2. [Figure 4] 13 is a flowchart showing a process of detecting passing by the control device. [Diagram 5] FIG. 4 is a block diagram showing a process of detecting passing by the control device. [Figure 6] 6 is a flowchart showing an example of a pad contact position estimation process performed by the control device. [Figure 7] 10 is a flowchart showing another example of the process of estimating the pad contact position by the control device. [Figure 8] 4 is a flowchart showing an example of a thrust force estimation process performed by the control device. [Figure 9] 10 is a flowchart showing another example of the thrust force estimation process performed by the control device. [Figure 10] FIG. 4 is a characteristic diagram showing an example of a change in current (Q-axis current) over time. [Figure 11] FIG. 4 is a characteristic diagram showing an example of a change in thrust force over time. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The electric brake device according to the embodiment will be described below with reference to the accompanying drawings, taking as an example a case where it is installed in a four-wheeled vehicle. Each step in the flow charts shown in Figures 4, 6, 7, 8, and 9 is represented by the letter "S" (for example, step 1 = "S1"). In Figure 1, the line with two diagonal lines represents an electrical system line.

[0013] 1, a vehicle 1 is equipped with a brake device 2 (vehicle brake device, brake system) that applies braking force to wheels (front wheels 3L, 3R, rear wheels 5L, 5R) to brake the vehicle 1. The brake device 2 includes left and right hydraulic brake devices 4, 4 (front braking mechanisms) provided corresponding to the left front wheel 3L and the right front wheel 3R, respectively, left and right electric brake devices 21, 21 (rear braking mechanisms) provided corresponding to the left rear wheel 5L and the right rear wheel 5R, respectively, a master cylinder 7 that generates hydraulic pressure in response to the operation (pressing) of a brake pedal 6 (operating tool), and a hydraulic pressure sensor 8 and a pedal stroke sensor 9 that measure the amount of operation of the brake pedal 6 by the driver.

[0014] The hydraulic brake device 4 is, for example, a hydraulic disc brake, and applies braking force to the wheels (front wheels 3L, 3R) by supplying hydraulic pressure (brake hydraulic pressure). The electric brake device 21 is, for example, a motorized disc brake, and applies braking force to the wheels (rear wheels 5L, 5R) by driving an electric motor 26. The hydraulic pressure sensor 8 and the pedal stroke sensor 9 are connected to the main ECU 10.

[0015] A hydraulic pressure supply device 11 (hereinafter referred to as ESC 11) is provided between the master cylinder 7 and the hydraulic brake devices 4, 4. The ESC 11 includes, for example, a plurality of control valves, a hydraulic pump for pressurizing brake hydraulic pressure, an electric motor for driving the hydraulic pump, and a hydraulic control reservoir for temporarily storing surplus brake fluid (none of which are shown). The control valves and electric motor of the ESC 11 are connected to a front hydraulic device ECU 12. The front hydraulic device ECU 12 includes a microcomputer having a calculation circuit (CPU) and a memory. The front hydraulic device ECU 12 controls the opening and closing of the control valves of the ESC 11 and the driving of the electric motor based on commands from the main ECU 10.

[0016] The main ECU 10 includes a microcomputer having a calculation circuit (CPU) and a memory. The main ECU 10 receives signals from the hydraulic pressure sensor 8 and the pedal stroke sensor 9 and calculates target braking forces for each wheel (four wheels) according to a predetermined control program. Based on the calculated braking forces, the main ECU 10 transmits braking commands for each of the two front wheels to a front hydraulic device ECU 12 (i.e., an ESCECU) via a CAN 13 (Controller area network) as a vehicle data bus. Based on the calculated braking forces, the main ECU 10 also transmits braking commands (target thrust forces) for each of the two rear wheels to rear electric brake ECUs 41, 41 via the CAN 13.

[0017] The main ECU 10 receives vehicle information transmitted from other ECUs (not shown) mounted on the vehicle via the CAN 13. That is, the main ECU 10 acquires various types of vehicle information via the CAN 13, such as the speeds of the wheels 3L, 3R, 5L, and 5R (wheel speeds), information on the AT range position or MT shift position, ignition on / off information, door opening / closing information, information on whether the driver's seat belt is fastened, information on the opening / closing of the door mirrors, engine RPM information, information on steering wheel operation, information on clutch operation, information on accelerator operation, information on vehicle-to-vehicle communication, information on the surroundings of the vehicle obtained by an in-vehicle camera, and information from an acceleration sensor (longitudinal acceleration, lateral acceleration).

[0018] The electric brake device 21 includes a brake mechanism 22 as an electric brake, and a main ECU 10 and a rear electric brake ECU 41 as control devices. Although not shown, the electric brake device 21 also includes a parking mechanism including a solenoid, etc. As shown in Fig. 1, the electric brake device 21 includes a rotation angle sensor 36 as a position detection means for detecting a motor rotation position and a current sensor 37 as a current detection means for detecting a motor current in order to perform position control and thrust control.

[0019] In the embodiment, there is no thrust sensor for detecting the thrust (piston thrust) of the brake mechanism 22. As will be described later, the thrust is estimated based on the current (current value) supplied to the electric motor 26. In the embodiment, the contact position (pad contact position) between the brake pad 23 and the disc rotor D is also estimated based on the current (current value) supplied to the electric motor 26.

[0020] The brake mechanism 22 is provided on each of the left and right wheels of the vehicle 1, i.e., on the left rear wheel 5L side and the right rear wheel 5R side. The brake mechanism 22 is an electric brake mechanism driven by an electric motor 26. As shown in Fig. 2, the brake mechanism 22 includes, for example, a brake pad 23 as a braking member (pad, friction pad), a caliper 24 as a cylinder (wheel cylinder), a piston 25 as a pressing member, an electric motor 26 also called an electric motor, a reduction mechanism 27, a rotary-linear motion conversion mechanism 28, and a fail-open mechanism 29.

[0021] The electric motor 26 is driven (rotated) by the supply of electric power to propel the piston 25. In this way, the electric motor 26 applies a braking force. The electric motor 26 is controlled by a rear electric brake ECU 41 based on a braking command (target thrust) from the main ECU 10. The reduction mechanism 27 is composed of, for example, a spur gear multi-stage reduction mechanism (not shown) and a planetary gear reduction mechanism 27A. The reduction mechanism 27 reduces the rotation of the electric motor 26 and transmits it to the rotation-to-linear motion conversion mechanism 28.

[0022] The rotary-to-linear motion conversion mechanism 28 converts the rotation of the electric motor 26, transmitted via the reduction gear mechanism 27, into an axial displacement (linear motion displacement) of the piston 25. The rotary-to-linear motion conversion mechanism 28 includes a spindle 28A and a nut 28B. The spindle 28A is rotatably provided in the caliper 24 via a rolling bearing 30. The piston 25 is driven by the electric motor 26 to move the brake pad 23. The brake pad 23 is pressed by the piston 25 against a disc rotor D, which serves as a braked member (disc). The disc rotor D rotates together with the wheels (rear wheels 5L, 5R).

[0023] When braking is applied, the fail-open mechanism 29 applies a rotational force in the brake release direction to the rotating member (spindle 28A) of the rotary-to-linear motion conversion mechanism 28. In the brake mechanism 22, the piston 25 is advanced by the drive of the electric motor 26 to press the brake pad 23 against the disc rotor D. That is, the brake mechanism 22 transmits a thrust force generated by the drive of the electric motor 26 to the piston 25 which moves the brake pad 23. If the electric motor 26 or the rear electric brake ECU 41 fails during braking, the fail-open mechanism 29 releases the braking force applied to the disc rotor D by the piston 25 (brake pad 23).

[0024] 3 shows the speed reducing mechanism 27 and the fail-open mechanism 29. The speed reducing mechanism 27 includes, for example, a first gear 31 that is a gear on the spindle 28A side of the rotary-linear motion conversion mechanism 28, and a second gear 32 that is a gear on the electric motor 26 side. The first gear 31 and the second gear 32 are in mesh with each other. The fail-open mechanism 29 is provided on the second gear 32 so as to face a side surface of the second gear 32. The fail-open mechanism 29 includes, for example, a torsion spring 33 as an elastic member, and a ratchet mechanism 34 as a torque limiter mechanism.

[0025] The torsion spring 33, also called a return spring, is located on the side of the second gear 32 and is provided concentrically with the second gear 32. The torsion spring 33 applies a torque (rotational force) to the second gear 32 in the direction of releasing the brake as the second gear 32 rotates. The torsion spring 33 is, for example, a "spiral spring." A base end 33A, which is an end on the inner diameter side of the torsion spring 33, is supported by a support pin 35 provided on the inner diameter side of the second gear 32. That is, the support pin 35 is provided on the side of the second gear 32 so as to protrude from the side. The base end 33A of the torsion spring 33 is fixed to the support pin 35. When the second gear 32 rotates, the base end 33A of the torsion spring 33 rotates together with the second gear 32.

[0026] When a torque (load) more than necessary is applied to the second gear 32 via the torsion spring 33, the ratchet mechanism 34 releases a part of the torque to adjust the torque to fall within a certain range. The ratchet mechanism 34 is provided on the caliper 24 side. That is, the ratchet mechanism 34 is fixed to the caliper 24 side without rotating. The ratchet mechanism 34 is formed in an annular shape, and the torsion spring 33 is disposed inside. The inner peripheral surface of the ratchet mechanism 34 is provided with a step on which one end of the torsion spring 33 is caught. That is, the inner peripheral surface of the ratchet mechanism 34 is provided with a plurality of projections 34A projecting toward the inner diameter side at equal intervals in the circumferential direction. The projections 34A of the ratchet mechanism 34 are engaged with the tip portion 33B, which is the end portion on the outer diameter side of the torsion spring 33. That is, the projection 34A corresponds to an engagement portion (ratchet) with which one end (tip portion 33B) of the torsion spring 33 engages.

[0027] When the spindle 28A rotates in the braking direction based on the rotation of the electric motor 26, a spring force is accumulated in the torsion spring 33, which is a "power spring," along with the rotation of the first gear 31 and the second gear 32. At this time, if the electric motor 26 becomes uncontrollable due to a malfunction of the electric motor 26 or the like, the spring force of the torsion spring 33 causes the spindle 28A to rotate in the reverse direction, which is the direction for releasing the brake. This reduces the pressing force of the brake pad 23, and the braking force can be released.

[0028] Tip portion 33B, which is one end of torsion spring 33, is caught on protrusion 34A of ratchet mechanism 34. Therefore, when the spring force accumulated in torsion spring 33 exceeds a certain level, tip portion 33B of torsion spring 33 gets over protrusion 34A of ratchet mechanism 34, and a part of the spring force of torsion spring 33 is released. As a result, the spring force of torsion spring 33 is maintained within a certain range.

[0029] This type of jumping over of the tip 33B of the torsion spring 33 occurs every time the brake pad 23 wears to a certain extent. That is, as wear of the brake pad 23 progresses, the brake pad 23 becomes thinner, and the piston 25 is pushed out in accordance with the amount of wear of the brake pad 23. As the piston 25 is pushed out, a spring force is accumulated in the torsion spring 33 accordingly. When the spring force of the torsion spring 33 exceeds a certain amount, jumping over occurs, and part of the spring force is released.

[0030] Next, the rear electric brake ECU 41 will be described. As shown in Fig. 1, the rear electric brake ECU 41 is provided for each of the brake mechanisms 22, 22, i.e., the brake mechanism 22 on the left side (left rear wheel 5L side) and the brake mechanism 22 on the right side (right rear wheel 5R side). The rear electric brake ECU 41 includes a microcomputer having a calculation circuit (CPU) and a memory. The rear electric brake ECU 41 controls the brake mechanism 22 (electric motor 26) based on a command from the main ECU 10.

[0031] That is, the rear electric brake ECU 41, together with the main ECU 10, constitutes a control device that controls the operation of the electric motor 26. In this case, the rear electric brake ECU 41 controls the drive of the electric motor 26 based on a braking command (target thrust). A braking command is input to the rear electric brake ECU 41 from the main ECU 10. The rear electric brake ECU 41 also controls a parking mechanism (not shown) (e.g., a solenoid) based on a command from the main ECU 10.

[0032] A rotation angle sensor 36 and a current sensor 37 are connected to the rear electric brake ECU 41. The rotation angle sensor 36 and the current sensor 37 are provided corresponding to each electric motor 26 of each brake mechanism 22. The rotation angle sensor 36 detects the rotation angle of the rotating shaft of the electric motor 26 (motor rotation angle). In other words, the rotation angle sensor 36 constitutes a position detection means that detects the rotation position of the electric motor 26 (motor rotation position). The current sensor 37 detects the current supplied to the electric motor 26 (motor current). In other words, the current sensor 37 constitutes a current detection means that detects the motor current of the electric motor 26.

[0033] The rear electric brake ECU 41 (and the main ECU 10 connected to the rear electric brake ECU 41 via the CAN 13) can obtain the rotation angle of the electric motor 26 based on a signal from the rotation angle sensor 36. The rear electric brake ECU 41 (and the main ECU 10) can obtain the motor current supplied to the electric motor 26 based on a signal from the current sensor 37.

[0034] As described later, the rear electric brake ECU 41 (and the main ECU 10) estimates the thrust acting on the piston 25 (the pressing force applied from the piston 25 to the brake pad 23) based on a signal from the current sensor 37. That is, the rear electric brake ECU 41 (and the main ECU 10) constitutes a thrust estimation means for estimating the thrust acting on the piston 25 (piston thrust).

[0035] Next, the operation of applying and releasing the brake while traveling by the electric brake device 21 will be described. Note that in the following explanation, the operation when the driver operates the brake pedal 6 will be described as an example. However, in the case of automatic braking, the operation is almost the same except that, for example, an automatic braking command is output from an automatic braking ECU (not shown) or the main ECU 10 to the rear electric brake ECU 41.

[0036] For example, when the driver depresses the brake pedal 6 while the vehicle 1 is traveling, the main ECU 10 outputs a command corresponding to the depressing operation of the brake pedal 6 (for example, a target thrust corresponding to a braking command) to the rear electric brake ECU 41 based on a detection signal input from the pedal stroke sensor 9. The rear electric brake ECU 41 drives (rotates) the electric motor 26 in the forward direction, i.e., in the braking application direction (apply direction), based on the command (target thrust) from the main ECU 10. The rotation of the electric motor 26 is transmitted to the rotary-linear motion conversion mechanism 28 via the reduction mechanism 27, and the piston 25 advances toward the brake pad 23.

[0037] As a result, the brake pads 23, 23 are pressed against the disc rotor D, applying a braking force. At this time, the driving of the electric motor 26 is controlled by detection signals from the pedal stroke sensor 9, the rotation angle sensor 36, the current sensor 37, etc., to establish a braking state. During such braking, a force in a braking release direction is applied by the torsion spring 33 of the fail-open mechanism 29 to the rotating member (spindle 28A) of the rotary-to-linear motion conversion mechanism 28, and ultimately to the rotating shaft of the electric motor 26.

[0038] On the other hand, when the brake pedal 6 is operated to release the brake pedal, the main ECU 10 outputs a command corresponding to this operation (for example, a target thrust corresponding to a brake release command) to the rear electric brake ECU 41. The rear electric brake ECU 41 drives (rotates) the electric motor 26 in the reverse direction, that is, in the brake release direction (release direction) based on the command from the main ECU 10. The rotation of the electric motor 26 is transmitted to the rotary-linear motion conversion mechanism 28 via the reduction mechanism 27, and the piston 25 retreats in a direction away from the brake pad 23. Then, when the brake pedal 6 is completely released, the brake pads 23, 23 are separated from the disc rotor D, and the braking force is released. In such a non-braking state where the brake is released, the torsion spring 33 of the fail-open mechanism 29 returns to its initial state.

[0039] Meanwhile, an electric brake device that does not use a thrust sensor uses the electric motor current (Q-axis current) instead of a thrust sensor to estimate the thrust of the electric brake and the pad contact position of the electric brake. For example, Japanese Patent Application Laid-Open No. 2012-159134 describes a technique for estimating the thrust based on the value of the current flowing through an electric motor. Also, for example, Japanese Patent Application Laid-Open No. 2008-57643 describes a technique for estimating the pad contact position based on the value of the current flowing through an electric motor.

[0040] For example, the thrust of the electric brake is estimated in the following order (A)-(C). (A) The currents for acceleration, friction, and viscous torque are subtracted from the raw data of the current (Q-axis current) passed through the electric motor. (B) Filter processing such as moving average processing using the rotation angle of the electric motor, etc., is performed to remove pulsation, etc. that is specific to electric motors. (C) Under the assumption that the current (Q-axis current) after these processes and the thrust are in a linear relationship, the thrust is calculated back from the current value (Q-axis current value).

[0041] For example, the pad contact position of an electric brake is estimated in the following order (a)-(c). (a) The current for friction and viscous torque is subtracted from the raw data of the current (Q-axis current) passed through the electric motor. (b) Filter processing such as moving average processing using the rotation angle of the electric motor, etc., is performed to remove pulsation, etc., specific to electric motors. (c) The pad contact position is obtained from the relationship between the current value after these processes (Q-axis current value) and the motor rotation amount at that time.

[0042] Here, the electric brake is equipped with a fail-open mechanism consisting of a torsion spring and a ratchet mechanism to mechanically release the thrust in the event of a failure. When the torque accumulated in the torsion spring exceeds a certain level, the ratchet mechanism functions as a torque limiter mechanism that releases part of the torque by having one end of the torsion spring overcome a step (protrusion) of the ratchet mechanism, and adjusts the amount of accumulated torque to be within a certain range. Such a fail-open mechanism is essential for an electric brake. However, when one end of the torsion spring of the fail-open mechanism overcomes the protrusion of the ratchet mechanism and the spring force of the torsion spring is released, the load on the electric motor suddenly decreases. This causes a sudden change in the electric motor current (Q-axis current), which may lead to a decrease in the estimation accuracy of the thrust and the estimation accuracy of the pad contact position.

[0043] FIG. 10 shows deviation of the estimated value of the pad contact position due to a sudden change in the Q-axis current. When the thrust increases due to contact between the brake pad and the disc rotor, the Q-axis current increases. For this reason, in the pad contact position estimation logic, the contact position is estimated by searching for the position where the current starts to increase. In FIG. 10, the solid characteristic line 51A and the dashed characteristic line 51B show the change in the Q-axis current when the pad contact position is accurately estimated. In contrast, when one end of the torsion spring overcomes the step (protrusion) of the ratchet mechanism, the Q-axis current suddenly drops, and as shown by the two-dot chain characteristic line 52, the change in the Q-axis current that deviates from the characteristic line 51 is recognized. That is, the Q-axis current that was correctly recognized as the solid characteristic line 51A and the dashed characteristic line 51B is recognized as the two-dot chain characteristic line 52 due to the overstep. As a result, an error occurs in the estimated value of the pad contact position.

[0044] On the other hand, Fig. 11 shows deviations in thrust estimation due to sudden changes in the Q-axis current. A solid characteristic line 53A and a dashed characteristic line 53B in Fig. 11 show changes in the Q-axis current when thrust estimation is performed accurately. The thrust is estimated using the Q-axis current. Therefore, when the Q-axis current suddenly drops as one end of the torsion spring overcomes a step (protrusion) of the ratchet mechanism, the estimated thrust is offset by the amount of the sudden drop in the Q-axis current from the moment the step is overcome, as shown by a two-dot chain characteristic line 54.

[0045] As shown in FIG. 10 and FIG. 11, normally (when there is no jumping over), the Q-axis current increases with the motor rotation amount. That is, the change in the Q-axis current with respect to the change in the motor rotation amount becomes positive. However, when jumping over occurs, the motor load decreases, so the Q-axis current suddenly drops. That is, the change in the Q-axis current with respect to the change in the motor rotation amount becomes negative. Therefore, in the embodiment, the jumping over of the torsion spring is detected using the change in the Q-axis current with respect to the change in the motor rotation amount as a trigger. That is, in the embodiment, the jumping over of the torsion spring is detected from the change in the Q-axis current with respect to the motor rotation amount, and the influence of the sudden change in the Q-axis current due to the jumping over of the torsion spring is eliminated by estimating the pad contact position and estimating the thrust. These points will be described below.

[0046] The electric brake device 21 includes a brake mechanism 22 as an electric brake, and a rear electric brake ECU 41 and / or a main ECU 10 as a control device. Hereinafter, the rear electric brake ECU 41 and / or the main ECU 10 are also simply referred to as "braking control devices 41, 10." The brake mechanism 22 includes an electric motor 26 and a fail-open mechanism 29. The electric motor 26 is controlled by a control unit (arithmetic circuit) of the braking control devices 41, 10. The fail-open mechanism 29 includes a torsion spring 33 and a ratchet mechanism 34.

[0047] The torsion spring 33 stores elastic energy when the electric motor 26 rotates forward to move the brake pad 23 in a direction to press the brake pad 23 against the disc rotor D. The torsion spring 33 releases elastic energy when the electric motor 26 rotates backward to move the brake pad 23 away from the disc rotor D. The ratchet mechanism 34 has a plurality of protrusions 34A with which the tip 33B, which is one end of the torsion spring 33, engages. The ratchet mechanism 34 is configured such that the tip 33B of the torsion spring 33 overcomes the protrusions 34A when the rotational torque acting on the torsion spring 33 when the electric motor 26 rotates forward exceeds a predetermined value. The predetermined value can be set as a value that can prevent the elastic energy stored in the torsion spring 33 from becoming excessive during braking and can release the braking force (thrust of the piston 25) by the brake pad 23 when the electric motor 26 or the like fails.

[0048] A control unit (arithmetic circuit) of the braking control device 41,10 controls the electric motor 26. At this time, the braking control device 41,10 estimates the thrust (estimates the thrust in the direction pressing the brake pad 23 against the disc rotor D) and the pad contact position (estimates the motor rotation angle at which the brake pad 23 starts pressing the disc rotor D) based on the value of the current passed through the electric motor 26. In addition, when the electric motor 26 rotates forward, the braking control device 41,10 detects that the tip 33B of the torsion spring 33 has climbed over the protrusion 34A based on a decrease in the value of the current passed through the electric motor 26 relative to the amount of rotation of the electric motor 26. The decrease in the current value may be, for example, the positive or negative of the current change (amount of change in current), or the amount of decrease (amount of sudden change) in current. That is, the climb over may be detected based on a decrease in the current change (amount of change in current) (from positive to negative), or based on the amount of decrease (amount of sudden change) in current exceeding a threshold value.

[0049] Fig. 4 shows a control process performed by the braking control device 41, 10 to detect the climbing over of the torsion spring 33. A processing program for executing the processing flow shown in Fig. 4, i.e., a processing program used for the control process of the climbing over detection, is stored in the memory of the braking control device 41, 10. The control process of Fig. 4 is executed, for example, as the process of S15 in Figs. 6 to 9 described later.

[0050] When the control process of FIG. 4 is started, the control unit (arithmetic circuit) of the braking control device 41, 10 calculates the time change of the motor rotation amount and the time change of the Q-axis current in S1. The "time change" corresponds to, for example, the "amount of change per unit time". In S2 following S1, the change (slope, amount of change) of the Q-axis current with respect to the motor rotation amount is calculated based on the two time changes calculated in S1. In S3 following S2, it is determined whether the change of the Q-axis current with respect to the motor rotation amount is 0 or more. If it is determined that "YES" is returned in S3, that is, the change of the Q-axis current with respect to the motor rotation amount is 0 or more, the process proceeds to S4. In S4, it is determined that the tip portion 33B of the torsion spring 33 has not passed over the protrusion 34A, and "0" corresponding to the signal "not passed over" is output. If "0" is output in S4, the process ends (returns).

[0051] On the other hand, if S3 returns "NO", that is, if it is determined that the change in the Q-axis current relative to the amount of motor rotation is less than 0, the process proceeds to S5. In S5, it is determined that the tip 33B of the torsion spring 33 has overcome the protrusion 34A, and a "1" corresponding to a "overstep" signal is output. When "1" is output in S5, the process ends (returns). Thus, in the control process of FIG. 4, if the change in the Q-axis current relative to the amount of motor rotation is positive, it is determined that the torsion spring 33 has not overcome the protrusion 34A of the ratchet mechanism 34, and a "0" is output. On the other hand, if the change in the Q-axis current relative to the amount of motor rotation is negative, it is determined that the torsion spring 33 has overcome the protrusion 34A of the ratchet mechanism 34, and a "1" is output.

[0052] FIG. 5 shows a block diagram of the braking control device 41,10 when the process of the flow chart of FIG. 4 is incorporated into software. As shown in FIG. 5, the braking control device 41,10 includes a current 1 / z unit 42, a current subtraction unit 43, a rotation amount 1 / z unit 44, a rotation amount subtraction unit 45, a change amount calculation unit 46, and an output unit 47. The braking control device 41,10 receives a Q-axis current from the current sensor 37, that is, a Q-axis current value passed through the electric motor 26. The braking control device 41,10 also receives a motor rotation amount from the rotation angle sensor 36, that is, the rotation amount of the electric motor 26. The Q-axis current value input to the braking control device 41,10 is input to the current 1 / z unit 42 and the current subtraction unit 43, and the motor rotation amount input to the braking control device 41,10 is input to the rotation amount 1 / z unit 44 and the rotation amount subtraction unit 45.

[0053] The Q-axis current value is input to the current 1 / z unit 42. The current 1 / z unit 42 outputs the Q-axis current value a predetermined number of samplings ago (i.e., a predetermined time ago) to the current subtraction unit 43. The current subtraction unit 43 receives the current Q-axis current value and the Q-axis current value a predetermined number of samplings ago (a predetermined time ago). The current subtraction unit 43 calculates the difference between the current Q-axis current value and the Q-axis current value a predetermined number of samplings ago (a predetermined time ago), that is, the amount of change in the Q-axis current value over the predetermined number of samplings (Δtime), and outputs this calculation result to the change amount calculation unit 46.

[0054] The motor rotation amount is input to the rotation amount 1 / z unit 44. The rotation amount 1 / z unit 44 outputs the motor rotation amount a predetermined number of samples ago (i.e., a predetermined time ago) to the rotation amount subtraction unit 45. The current motor rotation amount and the motor rotation amount a predetermined number of samples ago (a predetermined time ago) are input to the rotation amount subtraction unit 45. The rotation amount subtraction unit 45 calculates the difference between the current motor rotation amount and the motor rotation amount a predetermined number of samples ago (a predetermined time ago), that is, the change in the motor rotation amount for a predetermined number of samples (Δtime), and outputs this calculation result to the change amount calculation unit 46.

[0055] The change amount calculation unit 46 receives the change amount (difference) of the Q-axis current value and the change amount (difference) of the motor rotation amount between the predetermined number of samplings. The change amount calculation unit 46 calculates the change amount of the Q-axis current with respect to the motor rotation amount by dividing the change amount (difference) of the Q-axis current value by the change amount (difference) of the motor rotation amount. Here, the rotation amount subtraction unit 45 and the current subtraction unit 43 obtain the change amount of the motor rotation amount and the change amount of the Q-axis current as the difference between the current value and the value a predetermined number of samplings ago. In reality, if the time change amount (change amount per unit time) is to be calculated, each value should be divided by a predetermined number of sampling times (Δtime). However, this division is canceled by the next calculation process, that is, the division by the change amount calculation unit 46. Therefore, in the embodiment, the rotation amount subtraction unit 45 and the current subtraction unit 43 obtain the difference between the current value and the value a predetermined number of samplings ago.

[0056] The change amount calculation unit 46 calculates the "change amount of Q-axis current with respect to the amount of motor rotation" that is the criterion for determining whether the torsion spring 33 has been overcome by dividing the change amount of the Q-axis current value (the difference between Δtimes) by the change amount of the motor rotation amount (the difference between Δtimes). The change amount calculation unit 46 outputs the "change amount of Q-axis current with respect to the amount of motor rotation" that is the calculation result of the change amount calculation unit 46 to the output unit 47. The output unit 47 outputs "0" or "1" depending on whether the "change amount of Q-axis current with respect to the amount of motor rotation" that is the calculation result of the change amount calculation unit 46 is positive or negative. That is, when the calculation result of the change amount calculation unit 46 is positive (change amount≧0), the output unit 47 outputs "0 (not overcome)". When the calculation result of the change amount calculation unit 46 is negative (change amount<0), the output unit 47 outputs "1 (overcome)".

[0057] Next, the pad contact position estimation process will be described with reference to Fig. 6. Fig. 6 shows an example of the pad contact position estimation process performed by the braking control device 41, 10. A processing program for executing the processing flow shown in Fig. 6, i.e., a processing program used for the pad contact position estimation process, is stored in the memory of the braking control device 41, 10.

[0058] The control process in Fig. 6 is started, for example, when it is necessary to perform an estimation process of the pad contact position. When the control process in Fig. 6 is started, the control section (arithmetic circuit) of the braking control device 41, 10 operates the electric motor 26 in a predetermined pattern in S11. For example, the braking control device 41, 10 drives the electric motor 26 so that the piston 25 moves at a constant speed in order to estimate the pad contact position.

[0059] In S12 following S11, the Q-axis current value and the motor rotation amount required for estimating the pad contact position are accumulated. For example, the Q-axis current value and the motor rotation amount are stored in a memory. In S13 following S12, the effects of friction and viscosity are removed from the accumulated Q-axis current. Since the piston 25 is moved at a constant speed, friction and viscosity become fluctuation factors of the Q-axis current, and the effects of friction and viscosity are removed. In S14 following S13, the Q-axis current from which the effects of friction and viscosity have been removed is subjected to moving average processing.

[0060] In S15 following S14, a process of detecting whether the torsion spring 33 has gone over the protrusion 34A of the ratchet mechanism 34 is performed. In S16 following S15, it is determined whether the detection result in S15 is "1", that is, whether the tip 33B of the torsion spring 33 has gone over the protrusion 34A of the ratchet mechanism 34. If the result in S16 is "NO", that is, if it is determined that the torsion spring 33 has not gone over the protrusion 34A, the process proceeds to S17. In S17, the pad contact position is estimated from the Q-axis current value obtained in the processes from S12 to S14. Note that a specific calculation process for estimating the pad contact position based on the Q-axis current value is described in, for example, Japanese Patent Application Laid-Open No. 2008-57643. After the pad contact position is estimated in S17, the process ends. In other words, the process waits until the next pad contact position estimation is started.

[0061] On the other hand, if S16 returns "YES", that is, if it is determined that the torsion spring 33 has gone over the protrusion 34A, the process proceeds to S18. In S18, it is determined that the pad contact position is not calculated in this operation, and the motor rotation amount and Q-axis current accumulated up to that point are deleted, and the process ends. In this way, when the control unit (arithmetic circuit) of the braking control device 41, 10 detects that the tip portion 33B of the torsion spring 33 has gone over the protrusion 34A of the ratchet mechanism 34, it deletes the current value data. That is, when the control unit (arithmetic circuit) of the braking control device 41, 10 detects the going over, it deletes the data of the current value (Q-axis current value) supplied to the electric motor 26 corresponding to the rotation amount of the electric motor 26 accumulated from when the electric motor 26 starts rotating forward until it detects that the tip portion 33B of the torsion spring 33 has gone over the protrusion 34A.

[0062] As shown in Fig. 6, when the control section (arithmetic circuit) of the braking control device 41, 10 detects that the tip 33B of the torsion spring 33 has gone over the protrusion 34A, it discards data on the value of the current supplied to the electric motor 26 relative to the amount of rotation of the electric motor 26 that was accumulated before the detection. Then, the control section (arithmetic circuit) of the braking control device 41, 10 estimates the pad contact position based on data on the value of the current supplied to the electric motor 26 relative to the amount of rotation of the electric motor 26 that was accumulated after the detection. This makes it possible to prevent estimation from being made based on the data on the current value when the going over was detected.

[0063] The flow chart of Fig. 6 illustrates an example in which accumulated data of the current value (Q-axis current value) is deleted when jumping over is detected. In contrast to this, as shown in Fig. 7, data of the current value (Q-axis current value) may be complemented when jumping over is detected. That is, Fig. 7 illustrates another example of the pad contact position estimation process performed by the braking control device 41, 10. A processing program for executing the processing flow shown in Fig. 7 is stored in the memory of the braking control device 41, 10.

[0064] The processes from S11 to S17 in FIG. 7 are the same as those in FIG. 6. If the result of S16 in FIG. 7 is "YES", that is, if it is determined that the torsion spring 33 has climbed over the protrusion 34A, the process proceeds to S21. In S21, the missing portion due to the climbing is complemented. That is, in S21, the climbing portion is complemented with a curve. More specifically, in S21, the "broken characteristic line 51B" in FIG. 10 is estimated. In this case, the "broken characteristic line 51B" which is the missing portion is estimated from the "solid characteristic line 51A" in FIG. 10 which is the data before the climbing. In this case, the rising condition of the "broken characteristic line 51B" in FIG. 10 can be determined by referring to, for example, the "two-dot chain characteristic line 52" in FIG. 10. In this way, in the process of S21, the missing curve (broken characteristic line 51B) is estimated from the data before the climbing is detected (solid characteristic line 51A). After the crossing portion is complemented with a curve in S21, the process proceeds to S17, where the pad contact position is estimated using the complemented data.

[0065] In this way, when the control section (arithmetic circuit) of the braking control device 41, 10 detects that the tip portion 33B of the torsion spring 33 has gone over the protrusion 34A, the control section (arithmetic circuit) may complement (correct) data on the value of the current passed through the electric motor 26 relative to the amount of rotation of the electric motor 26. In this case, the control section (arithmetic circuit) of the braking control device 41, 10 complements data on the value of the current passed through the electric motor 26 relative to the amount of rotation of the electric motor 26 based on "data on the value of the current passed through the electric motor 26 relative to the amount of rotation of the electric motor 26 after it is detected that the tip portion 33B of the torsion spring 33 has gone over the protrusion 34A" and "data on the value of the current passed through the electric motor 26 relative to the amount of rotation of the electric motor 26 accumulated from when the electric motor 26 starts to rotate forward until it is detected that the tip portion 33B of the torsion spring 33 has gone over the protrusion 34A". At this time, the data missing due to the crossing (dashed characteristic line 51B in FIG. 10) is supplemented based on the data after the crossing is detected (dash-dotted characteristic line 52 in FIG. 10), for example, using as a reference the data accumulated from when the electric motor 26 starts rotating forward until the crossing is detected (solid characteristic line 51A in FIG. 10).

[0066] 7, when the control section (arithmetic circuit) of the braking control device 41, 10 detects that the tip 33B of the torsion spring 33 has overcome the protrusion 34A, it complements (corrects) data of the current value supplied to the electric motor 26 corresponding to the amount of rotation of the electric motor 26, which is accumulated before the detection. The control section (arithmetic circuit) of the braking control device 41, 10 estimates the pad contact position based on the complemented (corrected) data of the current value supplied to the electric motor 26 corresponding to the amount of rotation of the electric motor 26.

[0067] Next, the thrust force estimation process will be described with reference to Fig. 8. Fig. 8 shows an example of the thrust force estimation process performed by the braking control device 41, 10. A processing program for executing the processing flow shown in Fig. 8, i.e., a processing program used for the thrust force estimation process, is stored in the memory of the braking control device 41, 10.

[0068] The control process in Fig. 8 is started, for example, when it is necessary to perform a thrust estimation process. When the control process in Fig. 8 is started, the control section (arithmetic circuit) of the braking control device 41, 10 operates the electric motor 26 in a predetermined pattern in S11. In this case, the piston 25 cannot be moved at a constant speed.

[0069] In S12 following S11, the Q-axis current value and the motor rotation amount required for estimating the thrust are accumulated. For example, the Q-axis current value and the motor rotation amount are stored in a memory. In S31 following S12, the effects of friction, viscosity, and acceleration are removed from the accumulated Q-axis current. Since the piston 25 cannot be moved at a constant speed, acceleration is also a factor that causes fluctuations in the Q-axis current, and the effects of acceleration are also removed. In S14 following S31, the Q-axis current from which the effects of friction, viscosity, and acceleration have been removed is subjected to moving average processing.

[0070] The process of S15 and the process of S16 following S14 are the same as the process of S15 and S16 in Fig. 6 and Fig. 7. If the result of S16 is "NO", that is, if it is determined that the torsion spring 33 has not passed over the protrusion 34A, the process proceeds to S32. In S32, the thrust is estimated from the Q-axis current value acquired in the processes of S12 to S14. Note that a specific calculation process for estimating the thrust based on the Q-axis current value is described in, for example, JP 2012-159134 A. Once the thrust is estimated in S32, the process ends. In other words, the process waits until the next thrust estimation is started.

[0071] On the other hand, if S16 returns "YES", that is, if it is determined that the torsion spring 33 has gone over the protrusion 34A, the process proceeds to S17. In S17, it is determined that the thrust is not calculated in this operation, and the motor rotation amount and Q-axis current accumulated up to that point are deleted, and the process ends. As shown in FIG. 8, when the control unit (arithmetic circuit) of the braking control device 41, 10 detects that the tip portion 33B of the torsion spring 33 has gone over the protrusion 34A, it discards the data of the current value applied to the electric motor 26 corresponding to the rotation amount of the electric motor 26 accumulated before the detection. Then, the control unit (arithmetic circuit) of the braking control device 41, 10 estimates the thrust based on the data of the current value applied to the electric motor 26 corresponding to the rotation amount of the electric motor 26 accumulated after the detection. This makes it possible to prevent the estimation from being performed using the data of the current value when the going over is detected.

[0072] The flow chart of Fig. 8 illustrates an example in which accumulated data is deleted when overpassing is detected. In contrast, as shown in Fig. 9, data may be complemented when overpassing is detected. That is, Fig. 9 illustrates another example of the thrust estimation process performed by the braking control device 41, 10. A processing program for executing the processing flow shown in Fig. 9 is stored in the memory of the braking control device 41, 10.

[0073] If the result of S16 in FIG. 9 is "YES", that is, if it is determined that the torsion spring 33 has climbed over the projection 34A, the process proceeds to S21. In S21, the missing portion due to the climb is complemented. That is, in S21, the climbed portion is complemented with a curve. More specifically, in S21, the "broken characteristic line 53B" in FIG. 11 is estimated. In this case, the "broken characteristic line 53B" which is the missing portion is estimated from the "solid characteristic line 53A" in FIG. 11 which is the data before the climb. In this case, the rising condition of the "broken characteristic line 53B" in FIG. 11 can be determined by referring to, for example, the "two-dot chain characteristic line 54" in FIG. 11. In this way, in the process of S21, the missing curve (broken characteristic line 53B) is estimated from the data before the climb detection (solid characteristic line 53A). After the climbed portion is complemented with a curve in S21, the process proceeds to S32, and the thrust is estimated using the complemented data.

[0074] 9, when the control section (arithmetic circuit) of the braking control device 41,10 detects that the tip 33B of the torsion spring 33 has overcome the protrusion 34A, it complements (corrects) data of the current value applied to the electric motor 26 corresponding to the amount of rotation of the electric motor 26 that was accumulated before the detection. The control section (arithmetic circuit) of the braking control device 41,10 estimates the thrust force based on the complemented (corrected) data of the current value applied to the electric motor 26 corresponding to the amount of rotation of the electric motor 26.

[0075] As described above, according to the embodiment, the control unit (arithmetic circuit) of the braking control device 41, 10 detects that the tip 33B of the torsion spring 33 has gone over the protrusion 34A based on a decrease (amount of change becomes negative) in the value of the current applied to the electric motor 26 relative to the amount of rotation of the electric motor 26 when the electric motor 26 rotates forward. Therefore, based on the decrease in the current value, it is possible to accurately detect that the tip 33B of the torsion spring 33 has gone over the protrusion 34A. This makes it possible to suppress deterioration of the estimation accuracy based on the current value of the electric motor 26. That is, when the thrust is estimated based on the current value of the electric motor 26, the accuracy of the thrust (estimated value) can be improved and deterioration of the thrust estimation accuracy can be suppressed. Also, when the pad contact position is estimated based on the current value of the electric motor 26, the accuracy of the pad contact position (estimated value) can be improved and deterioration of the position estimation accuracy can be suppressed.

[0076] According to the embodiment, the control unit (arithmetic circuit) of the braking control device 41, 10 deletes the accumulated data when it detects that the tip portion 33B of the torsion spring 33 has gone over the protrusion 34A. Therefore, after it is detected that the tip portion 33B of the torsion spring 33 has gone over the protrusion 34A, it is possible to prevent the estimation of the thrust and the pad contact position from being performed using the data accumulated before the tip portion 33B of the torsion spring 33 went over the protrusion 34A. This makes it possible to prevent the deterioration of the estimation accuracy (thrust estimation accuracy, position estimation accuracy) based on the current value of the electric motor 26.

[0077] According to the embodiment, the control unit (arithmetic circuit) of the braking control device 41, 10 complements the data when it detects that the tip portion 33B of the torsion spring 33 has gone over the projection 34A. Therefore, after it is detected that the tip portion 33B of the torsion spring 33 has gone over the projection 34A, it is possible to estimate the thrust and the pad contact position based on the complemented data. This makes it possible to suppress deterioration of the estimation accuracy based on the current value of the electric motor 26 (thrust estimation accuracy, position estimation accuracy).

[0078] In this manner, in the embodiment, a sudden change in the Q-axis current, i.e., the tip 33B of the torsion spring 33 passing over the protrusion 34A, is detected. This improves the accuracy of estimating the pad contact position and the thrust force based on the Q-axis current. This makes it possible to suppress excess or deficiency of the brake torque, and improves the stability of the brake application. Furthermore, since the accuracy of estimating the pad contact position is improved, drag torque can be suppressed, and fuel efficiency can be improved.

[0079] In the embodiment, the fail-open mechanism 29 is configured by the torsion spring 33 and the ratchet mechanism 34, and the torsion spring 33 is a power spring, and the ratchet mechanism 34 is an internal ratchet wheel (internal gear) having wedge-shaped pawls (teeth). However, the present invention is not limited to this, and various configurations (elastic members) can be used for the torsion spring as long as it is configured to store elastic energy by the forward rotation of the electric motor. Also, various configurations (engagement members) can be used for the ratchet mechanism as long as it is configured to be released when the elastic energy (rotational torque) of the torsion spring exceeds a predetermined value.

[0080] In the embodiment, as shown in Figures 4 and 5, a case has been described in which it is detected that the tip end 33B of the torsion spring 33 has overcome the protrusion 34A based on the amount of change in the current value (Q-axis current value), i.e., whether the amount of change is positive or negative. However, this is not limiting, and it may be detected that one end of the torsion spring has overcome the engagement portion of the ratchet mechanism based on, for example, the amount of decrease in the current value (the amount of sudden change in the current that is determined to have overcome). In other words, it is possible to detect (determine) that one end of the torsion spring has overcome the engagement portion of the ratchet mechanism based on the decrease in the value of the current passed through the electric motor relative to the amount of rotation of the electric motor.

[0081] In the embodiment, the case where the jumping detection result (jumping over) is used to estimate the pad contact position and the thrust force has been described as an example. However, the present invention is not limited to this, and the jumping detection result (jumping over) may be used to estimate (determine) abnormality detection. In this case, the jumping over can be prevented from being determined as an abnormality, and the determination accuracy can be improved. In other words, the jumping detection result (jumping over) can be used for various estimations (determinations) based on the current value, such as estimation of the pad contact position, estimation of the thrust force, and abnormality detection.

[0082] In the embodiment, the "main ECU 10", the "rear electric brake ECU 41 on the left rear wheel 5L side", and the "rear electric brake ECU 41 on the right rear wheel 5R side" are each configured as separate ECUs, and these three ECUs are connected by the CAN 13, which is a vehicle data bus. That is, the three ECUs, the main ECU 10 and the left and right rear electric brake ECUs 41, 41, are configured as a control device (braking control device 41, 10) for the electric brake devices 21, 21. However, this is not limiting, and for example, the main ECU and the rear electric brake ECU may be configured as one ECU. That is, the control devices for controlling the left and right electric motors may be configured as one ECU.

[0083] In the embodiment, the rear electric brake ECU 41 is attached to the brake mechanism 22, and the brake mechanism 22 and the rear electric brake ECU 41 are configured as one unit (assembly). However, the present invention is not limited to this, and for example, the brake mechanism and the rear electric brake ECU may be arranged separately. In this case, the electric brake ECU (rear electric brake ECU) may be provided separately on the left side (left rear wheel side) and the right side (right rear wheel side), or one (common) electric brake ECU (rear electric brake ECU) may be configured on the left side (left rear wheel side) and the right side (right rear wheel side). In summary, the detection of climbing over may be performed by the rear electric brake ECU 41, the main ECU 10, or both the rear electric brake ECU 41 and the main ECU 10. That is, the detection of climbing over may be performed by at least one of the ECUs (control devices).

[0084] In the embodiment, the front wheels 3L, 3R are provided with hydraulic brake devices 4, 4, and the rear wheels 5L, 5R are provided with electric brake devices 21, 21. However, the present invention is not limited to this. For example, the front wheels may be provided with electric brake devices, and the rear wheels may be provided with hydraulic brake devices. Also, for example, both the front and rear wheels may be provided with electric brake devices.

[0085] According to the embodiment described above, the control device (in other words, the control unit that controls the electric motor) detects that one end of the torsion spring has overcome the engagement portion when the electric motor rotates forward, based on a decrease in the value of the current passed through the electric motor relative to the amount of rotation of the electric motor. Therefore, it is possible to accurately detect that one end of the torsion spring has overcome the engagement portion, based on a decrease in the current value. This makes it possible to suppress deterioration of the estimation accuracy based on the current value of the electric motor. For example, when estimating thrust based on the current value of the electric motor, it is possible to improve the accuracy of the thrust (estimated value), and suppress deterioration of the thrust estimation accuracy.

[0086] According to the embodiment, when the control device (control unit) detects that one end of the torsion spring has overcome the engagement portion, the control unit deletes the accumulated data. Therefore, after detecting that one end of the torsion spring has overcome the engagement portion, it is possible to suppress estimation using data accumulated before the end of the torsion spring has overcome the engagement portion. For example, it is possible to suppress estimation of thrust force using data accumulated before the end of the torsion spring has overcome the engagement portion. This makes it possible to suppress deterioration of estimation accuracy based on the current value of the electric motor (for example, thrust force estimation accuracy).

[0087] According to the embodiment, the control device (control unit) complements data when it detects that one end of the torsion spring has overcome the engagement portion. Therefore, after it is detected that one end of the torsion spring has overcome the engagement portion, estimation can be made based on the complemented data. For example, thrust can be estimated based on the complemented data. This makes it possible to suppress deterioration of estimation accuracy based on the current value of the electric motor (for example, thrust estimation accuracy). [Explanation of symbols]

[0088] 10 Main ECU (braking control unit, control unit) 21 Electric brake device 22 Brake mechanism (electric brake) 23 Brake pads (friction pads) 26 Electric Motor 33 Torsion Spring 33B Tip (one end) 34 Ratchet mechanism 34A Protrusion (engaging part) 41 Rear electric brake ECU (braking control device, control device) D Disc rotor (disc)

Claims

1. an electric motor controlled by a control unit; a torsion spring that stores elastic energy during forward movement in which the friction pad is moved in a direction pressing the friction pad against the disk by forward rotation of the electric motor, and releases the elastic energy during backward movement in which the friction pad is moved in a direction away from the disk by reverse rotation of the electric motor; a ratchet mechanism having a plurality of engagement portions with which one end of the torsion spring engages, the ratchet mechanism being configured such that, when a rotational torque acting on the torsion spring exceeds a predetermined value when the electric motor rotates in the forward direction, the one end of the torsion spring overcomes the engagement portions; A control device for an electric brake comprising: The control unit includes: When the electric motor rotates in the forward direction, it is detected that the one end of the torsion spring has overcome the engagement portion based on a decrease in a value of a current supplied to the electric motor with respect to an amount of rotation of the electric motor. Control device.

2. The control device according to claim 1 , The control unit includes: When it is detected that one end of the torsion spring has overcome the engagement portion, delete data of a current value applied to the electric motor with respect to an amount of rotation of the electric motor, the data having been accumulated during the period from when the electric motor starts to rotate in the forward direction until when it is detected that one end of the torsion spring has overcome the engaging portion; Control device.

3. The control device according to claim 1 , The control unit includes: When it is detected that one end of the torsion spring has overcome the engagement portion, data on the value of a current passed through the electric motor relative to the amount of rotation of the electric motor after it is detected that one end of the torsion spring has overcome the engaging portion, and data on the value of a current passed through the electric motor relative to the amount of rotation of the electric motor accumulated from when the electric motor starts to rotate forward until it is detected that one end of the torsion spring has overcome the engaging portion, are used to complement data on the value of a current passed through the electric motor relative to the amount of rotation of the electric motor. Control device.

4. An electric motor; a torsion spring that stores elastic energy during forward movement in which the friction pad is moved in a direction pressing the friction pad against the disk by forward rotation of the electric motor, and releases the elastic energy during backward movement in which the friction pad is moved in a direction away from the disk by reverse rotation of the electric motor; a ratchet mechanism having a plurality of engagement portions with which one end of the torsion spring engages, the ratchet mechanism being configured such that, when a rotational torque acting on the torsion spring exceeds a predetermined value when the electric motor rotates in the forward direction, the one end of the torsion spring overcomes the engagement portions; A method for controlling an electric brake comprising: A control unit for controlling the electric motor When the electric motor rotates in the forward direction, it is detected that the one end of the torsion spring has overcome the engagement portion based on a decrease in a value of a current supplied to the electric motor with respect to an amount of rotation of the electric motor. Control methods.

5. An electric motor; a torsion spring that stores elastic energy during forward movement in which the friction pad is moved in a direction pressing the friction pad against the disk by forward rotation of the electric motor, and releases the elastic energy during backward movement in which the friction pad is moved in a direction away from the disk by reverse rotation of the electric motor; a ratchet mechanism having a plurality of engagement portions with which one end of the torsion spring engages, the ratchet mechanism being configured such that, when a rotational torque acting on the torsion spring exceeds a predetermined value when the electric motor rotates in the forward direction, the one end of the torsion spring overcomes the engagement portions; a control device that detects, when the electric motor rotates in the forward direction, that one end of the torsion spring has overcome the engaging portion based on a decrease in a value of a current supplied to the electric motor relative to an amount of rotation of the electric motor; An electric brake device comprising:

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