JP2007132397A - Electric brake driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric brake driving device capable of providing intended braking force even in the case that a brake wire is elongated or a friction material of a brake is worn. <P>SOLUTION: As a stroke quantity P(F<SB>e</SB>) of a wire member X is determined based on a driving current value in an electric motor 2 and a moving quantity of the wire member X, an optimum braking force can be exhibited by changing the stroke quantity of the wire member X according to elongation of the wire member X or wear of the friction material of the brake. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electric brake drive device used for electrically driving a brake device in a vehicle or the like.

An electric parking brake device that drives or releases a parking brake by driving an electric motor by detecting a switch operation or a vehicle stop state is known. Patent Document 1 includes a screw mechanism that includes a screw shaft that is rotationally driven by an electric motor and a nut member that meshes with the screw shaft. By rotating the screw shaft and moving the nut member along the screw shaft, An electric parking brake device is disclosed that transmits a brake operating force to a wheel brake via a wire connected to a nut member.
JP 2000-309255 A

  In general, the braking force of the electric parking brake device is controlled based on the current value of the electric motor and the stroke amount of the wire that operates the parking brake, but the actual braking force is determined by the elongation of the brake wire or the friction material of the brake. There is a problem that it changes depending on the wear state. Therefore, if the brake wire stroke is fixed and the brake wire is excessively stretched or the brake friction material is excessively worn, there is a problem that the effectiveness of the parking brake is reduced. It is necessary to appropriately take measures such as manually adjusting the elongation of the brake wire and replacing the brake friction material.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an electric brake driving device that can obtain a desired braking force even when the brake wire is stretched or the friction material of the brake is worn. To do.

The electric brake driving device of the present invention is an electric brake driving device that transmits power of an electric motor via a wire member to a brake device that generates a braking force by pressing a friction member against a rotating body.
The pull-in amount of the wire member during the subsequent brake operation is determined based on the drive current value of the electric motor and the movement amount of the wire member during the preceding brake operation.

  According to the electric brake driving device of the present invention, the pull-in amount of the wire member during the subsequent brake operation is determined based on the drive current value of the electric motor and the movement amount of the wire member during the preceding brake operation. Therefore, the optimum braking force can be exerted by appropriately changing the amount of the wire member retracted in accordance with the elongation of the brake wire member or the wear of the brake friction material.

  It is preferable to issue an alarm when the determined pull-in amount of the wire member exceeds a threshold value. As a result, it is possible to notify that the extension of the brake wire or the wear of the friction material of the brake has approached the use limit, and prompt the exchange thereof.

  Next, an electric brake drive device for driving a brake device in an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of the actuator according to the present embodiment. 2 is a view of the configuration of FIG. 1 cut along the line II-II and viewed in the direction of the arrow. FIG. 3 is a view of the configuration of FIG. 2 cut along the line III-III and viewed in the direction of the arrow. is there. 4 is a view of the configuration of FIG. 2 taken along the line IV-IV and viewed in the direction of the arrow. In FIG. 1, a motor housing 1A to which an electric motor 2 is attached is connected to a cylindrical clutch housing 1B, and the motor housing 1A and the clutch housing 1B constitute the housing 1.

  A small gear 3 is connected to the rotating shaft 2a of the electric motor 2 driven by the control device ECU, and the small gear 3 is connected to an output shaft 4 rotatably supported by the motor housing 1A. Is engaged. The small gear 3 and the large gear 5 constitute a speed reduction mechanism. The output shaft 4 is connected to the screw shaft 21 of the power transmission mechanism 20 via the reverse input prevention mechanism 10. The speed reduction mechanism (3, 5) is separated from the power transmission mechanism 20 and the reverse input prevention mechanism 10 by the partition wall 6 attached to the housing 1, so that the lubricant, dust, etc. of the speed reduction mechanism can be sealed. It has become.

  In FIG. 2, the reverse input prevention mechanism 10 includes a drive unit 11, a cam unit 12, a lock member 13, a spring 14, and an outer ring 15 fixed to the housing 1. A female spline portion 11 a is formed on the inner periphery of the drive portion 11 and meshes with the male spline portion 4 a of the output shaft 4, so that the drive portion 11 rotates together with the output shaft 4. A female spline portion 12 a is formed on the inner periphery of the cylindrical cam portion 12, and this cam meshes with the male spline portion 21 b of the screw shaft 21, so that the cam portion 12 rotates integrally with the screw shaft 21. ing.

  The drive part 11 has three claw parts 11b extending in the axial direction from the outer periphery at equal intervals, and the claw part 11b is a concave groove provided on the outer periphery of the cam part 12, as shown in FIG. It fits in 12b and can move in the circumferential direction within the range of the concave groove 12b. A ball-shaped lock member 13 is rotatably disposed on the cam surface 12c serving as the bottom surface of the concave groove 12b, and the spring 14 is disposed in a spring hole 12d formed on the side surface of the concave groove 12b. Therefore, it is biased toward the claw portion 11b. The cam surface 12c is a slope that moves away from the axis as it goes in the circumferential direction (clockwise in FIG. 3).

  2 and 4, a thin cylindrical friction member 25 is disposed around a round shaft portion 21 c of the screw shaft 21, and a sleeve (inner ring) 26 is disposed so as to be fitted to the outer periphery of the friction member 25. . On the other hand, an outer ring 27 is fixed to the housing 1, and a cam portion 28 is fixed to the inner peripheral surface of the outer ring 27. The cam portion 28 is formed with a plurality of cam grooves 28a on the inner peripheral surface thereof that become deeper (away from the axis in the radial direction) in the circumferential direction (clockwise in the drawing), and the roller 29 further includes a sleeve 29. 26 is arranged so that the outer peripheral surface of 26 can roll within the range of the cam groove 29. The friction member 25 has a flange portion 25 a, and the flange portion 25 a is in contact with a flange portion 21 f formed on the screw shaft 21. The sleeve 26 is rotatably supported by the bearing 9 with respect to the fixed outer ring 27. The sleeve 26, the cam portion 28, and the rollers 29 constitute a one-way clutch mechanism 30.

  In FIG. 1, the screw shaft 21 can pass through a nut 22 to which a hollow cylindrical moving case 31 is attached. A male screw groove 21a is formed on the outer peripheral surface of the left half portion of the screw shaft 21 in FIG. 1, and a round shaft portion 21c is formed on the right half portion. On the other hand, a female screw groove 22a is formed on the inner peripheral surface of the nut 22 so as to face the male screw groove 21a, and a large number of balls 23 are formed in a spiral space (transfer path) formed by the screw grooves 21a and 22a. It is arranged to roll freely. A straight groove 22 b is formed on the outer periphery of the nut 22, and the tip of a detent 24 attached to the housing 1 is engaged therewith. Therefore, the nut 22 does not rotate and can move only in the axial direction. On the other hand, the screw shaft 21 can only rotate. The screw shaft 21 that is a rotating element, the nut 22 that is an axially moving element, and the ball 23 constitute a ball screw mechanism 40.

  The moving case 31 as a driven member is connected to the brake device 100 (see FIG. 5) via the wire member X, and always receives a biasing force in one direction (leftward in FIG. 1). . The power transmission mechanism 20 includes a one-way clutch mechanism 30, a friction member 25, and a ball screw mechanism 40.

  The rack teeth 22c are carved so as to extend in the axial direction with respect to the linear groove 22b of the nut 22 in a phase of 180 degrees (that is, at the lower end in FIG. 1). A spur gear 51 is rotatably supported with respect to the fixed case 1 so as to mesh with the rack teeth 22c. The amount of rotation of the spur gear 51 can be detected by an encoder 52 which is a detector. That is, since the nut 22 is connected to the moving case 31, the moving amount of the moving case 31 (that is, the driving amount of the wire member X of the brake device 100) corresponds to the moving amount of the nut 22 in the axial direction. The amount of rotation of the gear 51 can be converted to be detected by the encoder 52. An electrical signal corresponding to the amount of movement of the moving case 31 detected by the encoder 52 is transmitted to the control device ECU.

  FIG. 5 is a front view of the brake device 100, but the surrounding brake drum (rotating body) is omitted. In FIG. 5, reference numeral 101 denotes a stationary back plate, on which opposing brake shoes (friction members) 102 and 103 are movably mounted. The brake shoes 102 and 103 are formed in a T-shaped cross section from the rims 104 and 104 and the webs 105 and 105, respectively, and linings 106 and 106 are fixed to the outer periphery of the rims 104 and 104, respectively.

  A wheel cylinder 107 is disposed between the upper opposing ends of one brake shoe 102 and another brake shoe 103, and expands the brake shoes 102 and 103 by a service brake. The wheel plate 107 is attached to the back plate 101 by bolts or the like. While being fixed, the pistons 107a and 107a are in light contact with the upper opposing ends of the webs 105 and 105, respectively.

  Reference numeral 108 denotes an anchor member that supports the lower opposing ends of one brake shoe 102 and another brake shoe 103, and is fixed to the back plate 101 with two rivets 109, 109, for example. In the anchor member 108, 108 b is an extended portion extending from the main body portion 108 a and serves as a housing portion for a parking brake return spring (hereinafter simply referred to as a return spring). That is, a return spring that guides and inserts an urging force by inserting the wire member X is assembled in the accommodating portion 108b.

  The parking brake lever 110 is arranged so as to overlap the web 105 of the brake shoe 103, and its base 110a is rotatably supported by a pin 111 in the vicinity of the upper end of the web 105, and is connected to the free end 110b. The U-groove connecting the wire member X is folded back. That is, the wire member X is connected to the free end 110b, and one end of a return spring through which the wire member X is inserted is in contact. Here, the return spring is positioned by being supported by a support portion (not shown) provided on the back plate 101 at the other end.

112 is a shoe clearance automatic adjusting device, which is suspended between the brake shoes 102 and 103 adjacent to the wheel cylinder 107. The shoe gap automatic adjusting device 112 is configured to automatically adjust so that a gap between a brake drum (not shown) and the brake shoes 102 and 103 is always kept constant.
The brake operation with such a configuration will be described.

  The operation of this embodiment will be described. At the time of service braking, when the wheel cylinder 107 is pressurized by hydraulic pressure from a master cylinder (not shown), the brake shoes 102 and 103 are expanded with the contact point with the anchor member 108 as a fulcrum, and the rotating brake This can be braked by frictional engagement with a drum (not shown).

  On the other hand, when operating the parking brake, when the operator operates an operation button (not shown), electric power is supplied from the battery (not shown) to the electric motor 2 via the control unit ECU, and the rotary shaft 2a rotates. The rotational force of the rotating shaft 2 a is transmitted to the output shaft 4 through the small gear 3 and the large gear 5. At this time, in FIG. 3B, if the output shaft 4 rotates in the direction of the arrow C, the drive unit 11 also rotates in the same direction, and the claw unit 11b rotates clockwise on the side surface of the groove 12b of the cam unit 12. It will be pushed. In such a case, even if the lock member 13 is in the locked position, the lock member 13 is moved by the frictional force so that the radial space between the inner peripheral surface of the outer ring 15 and the cam surface 12c is wider. Reference numeral 13 is not a resistance, but a rotational force is transmitted from the drive unit 11 to the cam unit 12.

  When the cam portion 12 rotates, the screw shaft 21 receives rotational force in the same direction. At this time, the sleeve 26 also tries to rotate in the same direction via the friction member 25. However, in FIG. 4, the rotation of the sleeve 26 in the C direction (clockwise) is free because the roller 29 does not move to the locked position. Therefore, the rotation of the screw shaft 21 is allowed.

  When the screw shaft 21 rotates, the nut 22 is pushed out in the axial direction in a low friction state by the ball 23 rolling in the spiral space (transfer path) formed by the screw grooves 21a and 22a. It is converted into 22 axial displacements. As the nut 22 moves in the axial direction, the moving case 31 moves (in FIG. 1, the moving case 31 moves in a direction approaching the housing 1). Therefore, the power is applied to the brake device 100 via the wire member X. Is transmitted to. As a result, the parking brake lever 110 rotates counterclockwise about the pin 111, and the acting force is transmitted to one brake shoe 102 via the strut member of the shoe gap automatic adjusting device 112, and the brake shoe 102 expands the contact point with the anchor member 108 as a fulcrum and frictionally engages with a brake drum (not shown). Then, the reaction force acts on the pin 111 and the other brake shoe 103 is similarly expanded, and is frictionally engaged with a brake drum (not shown).

  When the encoder 52 detects that the moving case 31 has moved by a specified amount, the encoder 52 transmits a signal to the control device ECU, and the control device ECU stops the power supply to the electric motor 2, so that the rotating shaft 2a stops. .

  On the other hand, when the operator completes or interrupts the operation of the operation button, the electric motor 2 is stopped. Even in this case, the urging force of the brake device 100 is constantly acting on the wire member X, and thus the urging force is applied. The displacement in the axial direction of the moving case 31 and the nut 22 thus converted is converted into the rotational displacement of the screw shaft 21, and thus the cam portion 12 also rotates in the same direction. At this time, in FIG. 3B, if the cam portion 12 b rotates in the direction of arrow B (counterclockwise in the figure) and the drive portion 11 remains stationary, the lock member 13 of the outer ring 15 is supported while being supported by the spring 14. Since the radial space between the inner peripheral surface and the cam surface 12c moves in a narrower direction, the cam portion 12 is locked to the outer ring 15 by a so-called wedge effect. This is called a position holding state. Accordingly, the rotational force is not transmitted from the cam portion 12 to the drive portion 11, and the braking operation of the parking brake can be continued without supplying electric power to the electric motor 2, thereby saving energy.

  Further, when the operator reversely operates the operation button for releasing the parking brake, reverse polarity power is supplied to the electric motor 2 via the control unit ECU, and the rotary shaft 2a rotates in the reverse direction. The rotational force of the rotating shaft 2 a is transmitted to the output shaft 4 through the small gear 3 and the large gear 5. 3A, if the output shaft 4 rotates in the direction of arrow A, the drive unit 11 also rotates in the same direction, and the claw portion 11b rotates the lock member 13 counterclockwise in FIG. Will be pressed. When the lock member 13 is pushed in the radial direction, the lock member 13 moves in a direction in which the radial space between the inner peripheral surface of the outer ring 15 and the cam surface 12c is wider. Further, the claw portion 11b of the drive unit 11 presses the side surface provided with the spring hole 12d of the concave groove 12b via the lock member 13, so that the rotational force is transmitted from the drive unit 11 to the cam unit 12. Become.

  When the cam portion 12 rotates, the screw shaft 21 receives rotational force in the same direction. At this time, the sleeve 26 also tries to rotate in the same direction via the friction member 25, but in FIG. 4, the roller 29 moves to the locked position by the rotation of the sleeve 26 in the A direction (counterclockwise). Therefore, the rotation of the sleeve 26 is prevented with respect to the fixed outer ring 27. However, if the torque of the electric motor 2 is sufficiently large, the screw shaft 21 can be rotated by overcoming the frictional force of the friction member 25, and the moving case 31 moves to the left in FIG. The tension of the wire member X is reduced, and the braking of the wheel in the brake device 100 can be released. By placing the one-way clutch mechanism 30 in the engaged state in this manner, rattling can be effectively prevented. Here, when the encoder 52 detects that the moving case 31 has moved by a specified amount, the encoder 52 transmits a signal to the control device ECU, and the control device ECU stops the power supply to the electric motor 2. Is stationary.

  By the way, the electric brake drive device can be driven with high accuracy based on the amount of movement of the wire member X only in the initial state where the brake shoes 102 and 103 are not worn and the wire member X does not stretch. That is, the brake shoes 102 and 103 are worn and thinned according to use, and the wire member X may be elongated due to deterioration over time.

  FIG. 6 is a diagram illustrating an example of load-stroke characteristics of the drum brake. In FIG. 6, when the extension amount of the wire member X is 0 mm (graph A), in order to apply a load of 1250 N (for example, a braking force necessary on a flat ground) to the brake shoes 102 and 103, a 19 mm pull-in amount (stroke) However, when the elongation amount of the wire member X becomes 3 mm (graph B), a load of 800 N is obtained with a stroke amount of 19 mm, and when the elongation amount of the wire member X becomes 6 mm (graph C). When the stroke amount is 19 mm, the load is 500 N, and the braking force is less than half. In addition, if the brake shoes 102 and 103 are worn, the braking force may be further reduced even if the same stroke amount is applied. That is, simply driving the wire member X with the initial stroke amount may cause the brake shoes 102 and 103 not to contact the drum brake with a necessary load due to deterioration over time, and thus a desired braking force may not be exhibited. Therefore, control of the electric brake driving device that can obtain a desired braking force even when the brake shoes 102 and 103 are worn or the wire member X is elongated will be described.

  FIG. 7 is a diagram showing a control block in the control device ECU. FIG. 8 is a graph showing a change in current generated at the terminal of the electric motor with time. Here, it is expressed as a correction amount ΔS for further retracting the movable case 31 according to the amount of elongation of the wire member X and the wear amount of the brake shoes 102 and 103, and the relationship between the load and the stroke is reviewed according to the correction amount ΔS. ing.

  In this embodiment, the drive current of the electric motor 2 is used to obtain the correction amount ΔS. As shown in FIG. 8, the drive current of the electric motor 2 has a characteristic that it is low in a state close to no load and increases as the load on the brake shoes 102 and 103 increases. Therefore, by determining the relationship between the drive current of the electric motor 2 and the load of the brake shoes 102 and 103 by experiments or conditional expressions performed in advance, the maximum value of the drive current of the electric motor 2 can be measured. Correspondingly, it can be said that the loads of the brake shoes 102 and 103 can be obtained. However, as shown in FIG. 8, due to the characteristics of the electric motor 2, a high current called a surge current (or inrush current) is generated immediately after the current is supplied. Therefore, in the present embodiment, the sampling of current is started from 100 ms after the input of the braking force command, and the sampling is terminated after the position control, thereby eliminating the influence of the surge current.

When a braking force command is input to the control unit ECU according to the operation of the operator, the stroke determination unit C1 determines a necessary stroke amount. When the extension amount of the wire member X is 0 mm and the brake shoes 102 and 103 are in a new state, such as immediately after maintenance, an initial stroke amount P (F ₀ ) with a correction amount ΔS = 0 is output. The initial stroke amount P (F ₀ ) is input to the PWM drive unit C4 via the PID control unit C2 and the current limiter C3, and is converted into a necessary drive current from this and supplied to the electric motor 2. The encoder 52 detects the amount of movement of the moving case 31 moved by the electric motor 2 and applies feedback control to the PID control unit C2. Accordingly, the moving case 31 can be moved with high accuracy without overshoot.

Here, the drive current of the electric motor 2 is sampled by a current sensor (not shown), and the maximum current value detection unit C5 obtains the maximum value based on the sampling data. The substantial output load calculation unit C6 calculates the maximum load of the brake shoes 102 and 103 by substituting the obtained maximum current value into the following equation.
F = (i · Kt · 2π · μ ₀ ) / l · N · μ ₁ (1)
P = (Kt · 2π · μ ₀ · N · μ ₁ ) / l (2)
F = P · i (3)
However,
Kt: Torque constant of the electric motor 2 [Nm / A]
μ ₀ : Ball screw positive operating efficiency [%]
l: Ball screw lead [m]
N: Reduction ratio of reduction mechanism μ ₁ : Gear efficiency of reduction mechanism [%]
F: Real output load of brake shoes 102 and 103 [N]
P: Actuator output coefficient (varies according to the mechanical configuration of the actuator)
i: Maximum motor current [A]
It should be noted that the relationship between the drive current of the electric motor 2 and the load of the brake shoes 102 and 103, which are obtained in advance by experiments or the like, is stored as a table, and based on this, the maximum load of the brake shoes 102 and 103 is obtained. Also good.

Here, the correction amount determination unit C7 compares the stored maximum load of the brake shoes 102 and 103 with the calculated maximum load of the brake shoes 102 and 103, and if it is determined that they are substantially equal, the correction amount ΔS. = 0 is maintained. Therefore, at the time of the next braking operation, the initial stroke amount P (F ₀ ) is again given according to the input command.

On the other hand, as a result of comparison with the stored maximum load of the brake shoes 102 and 103, the correction amount determination unit C7 determines that the calculated maximum load of the brake shoes 102 and 103 is below the allowable limit value. In this case, the correction amount ΔS is determined based on the difference between the stored maximum load and the calculated maximum load. More specifically, for example, taking the graph of FIG. 6 as an example, when the initial stroke amount P (F ₀ ) = 19 mm, it is assumed that the maximum load is 1250 N, and the actual maximum load is 800 N during use. When it falls, it turns out that it is necessary to draw in the wire member X by 3 mm more. That is, the correction amount determination unit C7 determines that the correction amount ΔS = 3 mm.

The correction amount determination unit C7 inputs the determined correction amount ΔS to the stroke determination unit C1, and performs feedback control. As a result, during the next braking operation, the stroke amount P (F _e ) = P (F ₀ ) + ΔS is given according to the input command, so the maximum load of the brake shoes 102 and 103 returns to 1250N. Sufficient braking force can be demonstrated. In the graph shown in FIG. 6, the load-stroke characteristic is obtained for every elongation of 3 mm of the wire member. For example, the load-stroke characteristic is obtained for each 0.5 mm of elongation of the wire member, and is mapped to a database. If it is stored in a non-volatile memory in the control unit ECU and the correction amount ΔS is given every 0.5 mm while referring to the actual maximum load, it is possible to perform more accurate control.

  However, in a state where the correction amount ΔS exceeds a predetermined value, the wire member X reaches the elongation limit or the wear limit of the brake shoes 102, 103, or the wire member X is disconnected or cut due to an unexpected situation. There is a fear. Therefore, when the correction amount ΔS determined based on the calculated maximum load of the brake shoes 102 and 103 exceeds the threshold value, the correction amount determination unit C7 displays alarm indication lighting, a buzzer sound, etc. in the instrument panel. An alarm can be issued. With this warning, the operator can recognize that the maintenance of the brake device is necessary.

  The present invention has been described above with reference to the embodiments. However, the present invention should not be construed as being limited to the above-described embodiments, and can be modified or improved as appropriate. For example, the nut may be rotated by an electric motor and the screw shaft may be moved in the axial direction. Furthermore, various detectors such as an encoder, a potentiometer, and a resolver can be used as the pull-in position amount detector.

It is sectional drawing of the actuator which is this Embodiment. It is the figure which cut | disconnected the structure of FIG. 1 by the II-II line | wire, and looked at the arrow direction. It is the figure which cut | disconnected the structure of FIG. 2 by the III-III line | wire, and looked at the arrow direction. It is the figure which cut | disconnected the structure of FIG. 2 by the IV-IV line and looked at the arrow direction. 2 is a front view of the brake device 100. FIG. It is a figure which shows the example of the load-stroke characteristic of a drum brake. It is a figure which shows the control block in control apparatus ECU. It is a graph which shows the change of the electric current which generate | occur | produces in the terminal of an electric motor with time.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Housing 1 Fixed case 1A Motor housing 1B Clutch housing 2 Rotating shaft 2 Electric motor 2a Rotating shaft 3 Small gear 4 Output shaft 4a Male spline part 5 Large gear 6 Bulkhead 9 Bearing 10 Reverse input prevention mechanism 11 Drive part 11a Female spline part 11b Claw part 12 Cam part 12a Female spline part 12b Cam part 12b Concave groove 12c Cam surface 12d Spring hole 13 Lock member 14 Spring 15 Outer ring 20 Power transmission mechanism 21 Screw shaft 21a Male screw groove 21b Male spline part 21c Round shaft part 21f Flange part 22 Nut 22a Female thread groove 22b Linear groove 22c Rack teeth 23 Ball 24 Non-rotating 25 Friction member 25a Flange portion 26 Sleeve 27 Outer ring 28 Cam portion 28a Cam groove 29 Cam groove 30 One-way clutch mechanism 31 Moving case 40 Bo Screw mechanism 51 Spur gear 52 Encoder 100 Brake device 101 Back plate 102, 103 Brake shoe 104 Rim 105 Web 105, 105 Web 106, 106 Lining 107 Wheel cylinder 107a, 107a Piston 108 Anchor member 108a Body portion 108b Housing portion 109, 109 Rivet 110 Lever 110a Base 110b Free end 111 Pin 112 Shoe clearance automatic adjustment device C1 Stroke determination unit C2 PID control unit C3 Current limiter C4 PWM drive unit C5 Maximum current value detection unit C6 Substantive output load calculation unit C7 Correction amount determination unit ECU Control Device X Wire member

Claims (2)

In the electric brake drive device that transmits the power of the electric motor via the wire member to the brake device that generates the braking force by pressing the friction member against the rotating body,
An electric brake driving device that determines a pull-in amount of the wire member during a subsequent brake operation based on a drive current value of the electric motor and a movement amount of the wire member during a preceding brake operation . 2. The electric brake driving device according to claim 1, wherein an alarm is issued when the determined amount of drawing of the wire member exceeds a threshold value.

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