Estimation device, brake control device, and estimation method

Description

Technical Field

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[0001] The present disclosure relates to an estimation device, a brake control device, and an estimation method.

Background Art

[0002] Railway vehicles are equipped with a mechanical brake device that generates mechanical braking force by pressing a friction material against a rotating body that rotates when the railway vehicle is running. The friction material wears out every time it is pressed against the rotating body. When the friction material wears out, the gap between the friction material and the rotating body when the mechanical brake device is stopped increases. Therefore, after the mechanical brake device starts operating, the time until the friction material contacts the rotating body and mechanical braking force is generated becomes longer. In other words, the responsiveness of the mechanical brake device decreases. In order to maintain the responsiveness of the mechanical brake device by maintaining the friction material at an appropriate timing, a device for estimating the wear amount of the friction material is used. This type of wear amount estimation device is disclosed in Patent Document 1.

[0003] The wear amount calculation device disclosed in Patent Document 1 obtains the rotational angle position of the component member from the signal acquired from a rotation sensor attached to a component member of a gap adjustment mechanism that adjusts the gap between the friction material and the rotating body, and calculates the wear amount of the friction material from the rotational angle position.

Prior Art Documents

Patent Documents

[0007] To achieve the above objective, the estimation device according to this disclosure estimates the amount of wear of the friction material of a mechanical brake system, which comprises a pressing mechanism that generates a mechanical braking force by pressing a friction material against a rotating body that rotates when a vehicle is in motion using the rotational force of a motor, and a gap adjustment mechanism that maintains the distance between the friction material and the rotating body within a target range when the pressing mechanism has stopped pressing by performing a mechanical operation to bring the friction material closer to the rotating body. The estimation device comprises a discrimination unit and an estimation unit. The discrimination unit determines whether or not the gap adjustment mechanism has performed a mechanical operation based on the starting rotation amount, which is the amount of rotation of the motor from when the motor starts rotating until the friction material comes into contact with the rotating body. The estimation unit estimates the amount of wear of the friction material from the number of times the gap adjustment mechanism has performed a mechanical operation. [Effects of the Invention]

[0008] The estimation device according to this disclosure determines whether or not there is a mechanical action by the gap adjustment mechanism of the mechanical brake device that brings the friction material closer to the rotating body, based on the rotational speed at startup of the motor that generates power to press the friction material against the rotating body, and estimates the amount of wear of the friction material from the number of times the mechanical action of bringing the friction material closer to the rotating body has been performed. As a result, an estimation device that can estimate the amount of wear of the friction material with a simple configuration is obtained. [Brief explanation of the drawing]

[0009] [Figure 1] Block diagram of the brake control system according to Embodiment 1 [Figure 2] Diagram showing the configuration of the mechanical brake device according to Embodiment 1. [Figure 3] A diagram showing an example of the operation of a mechanical brake device according to Embodiment 1. [Figure 4]This figure shows an example of wear of the friction material in a mechanical brake device according to Embodiment 1. [Figure 5] A diagram showing an example of the operation of a mechanical brake device according to Embodiment 1. [Figure 6] This figure shows an example of the operation of the gap adjustment mechanism provided in the mechanical brake device according to Embodiment 1. [Figure 7] A diagram showing the hardware configuration of the brake control device according to Embodiment 1. [Figure 8] A flowchart showing an example of the operation of the wear amount estimation process performed by the estimation device according to Embodiment 1. [Figure 9] This figure shows an example of the rotational speed of the motor at startup of the mechanical brake device according to Embodiment 1. [Figure 10] Block diagram of the brake control system according to Embodiment 2 [Figure 11] A flowchart showing an example of the operation of the wear amount estimation process performed by the estimation device according to Embodiment 2. [Figure 12] A diagram showing a modified configuration of the mechanical brake device according to the embodiment. [Figure 13] This figure shows an example of the operation of a modified mechanical brake device according to the embodiment. [Figure 14] A diagram showing a modified example of the hardware configuration of the brake control device according to the embodiment. [Modes for carrying out the invention]

[0010] Hereinafter, the estimation device, brake control device, and estimation method according to the embodiments of this disclosure will be described in detail with reference to the drawings. In the drawings, the same or equivalent parts are denoted by the same reference numerals.

[0011] (Embodiment 1) An estimating device for estimating the wear amount of a friction material included in a mechanical brake device that is mounted on a railway vehicle and generates a mechanical brake force by the rotational force of a motor, and a brake control device including the estimating device will be described in Embodiment 1. In Embodiment 1, the railway vehicle decelerates by the mechanical brake force generated by the mechanical brake device. The brake control system 100 shown in FIG. 1 includes a mechanical brake device 30 that generates a mechanical brake force by the rotational force of a motor 31, and a brake control device 1 that controls the mechanical brake device 30. In FIG. 1, only the components related to electrical control among the components of the mechanical brake device 30 are shown.

[0012] The brake control device 1 includes, for example, a target brake force determination unit 11 that obtains a target brake force, which is a target value of the brake force, from a brake command acquired from an operation unit 41 provided on the driver's cab, a target mechanical brake force determination unit 12 that obtains a target mechanical brake force, which is a target value of the mechanical brake force by the mechanical brake device 30, from the target brake force, a brake control unit 13 that controls the mechanical brake device 30 according to the target mechanical brake force, and an estimating device 18 that estimates the wear amount of the friction material included in the mechanical brake device 30.

[0013] To avoid complication of the drawing, in FIG. 1, one mechanical brake device 30 is shown as the control target of the brake control device 1, but the brake control device 1 controls a plurality of mechanical brake devices 30. The mechanical brake device 30 is provided, for example, for each wheel of the railway vehicle. In FIG. 1, the brake control device 1 includes one brake control unit 13, but the brake control device 1 may include a brake control unit 13 for each brake control unit, specifically, for each wheel, axle, or bogie.

[0014] As shown in FIGS. 2 and 3, the mechanical brake device 30 controlled by the brake control device 1 having the above configuration generates a brake force by pressing a friction material 50 against a rotating body 60 that rotates when the railway vehicle is running. The mechanical brake device 30 is provided for each rotating body 60. The friction material 50 is a brake wheel, a brake pad, or the like. The rotating body 60 is a wheel, a disk rotor, or the like.

[0015] The mechanical brake device 30 includes a motor 31 driven by electric power supplied from the brake control device 1 to rotate a drive shaft 31a, a speed reducer 32 that decelerates the rotation of the motor 31 and increases torque for output, and a pressing mechanism 33 that is connected to the drive shaft 31a via the speed reducer 32 and generates a mechanical braking force by pressing a friction material 50 against a rotating body 60 with the rotational force of the drive shaft 31a, a gap adjusting mechanism 36 that adjusts the distance between the friction material 50 and the rotating body 60 by bringing the friction material 50 closer to the rotating body 60 through a mechanical operation, and the friction material 50 attached to the pressing mechanism 33.

[0016] The pressing mechanism 33 is a rotary-linear motion conversion mechanism having an output shaft 34 to which the friction material 50 is attached and a holding member 35 that holds the output shaft 34. The output shaft 34 linearly moves in a direction approaching the rotating body 60 or away from the rotating body 60 in accordance with the rotation of the motor 31.

[0017] The mechanical brake device 30 includes a load cell 37 attached to one end of the output shaft 34 to measure the pressing force, which is the force by which the pressing mechanism 33 presses the friction material 50 against the rotating body 60, and an encoder 38 attached near the motor 31 to output a pulse signal corresponding to the rotation of the motor 31.

[0018] The motor 31 is, for example, a three-phase induction motor driven by three-phase alternating current power supplied from the brake control device 1. As the output shaft 34 of the pressing mechanism 33 linearly moves in accordance with the rotation of the motor 31, the friction material 50 attached to one end of the output shaft 34 moves in a direction approaching the rotating body 60 or away from the rotating body 60.

[0019] When the mechanical brake device 30 is stopped, in other words, when the pressing mechanism 33 has stopped pressing, the friction material 50 is separated from the rotating body 60, as shown in Figure 2. Let W1 be the distance between the friction material 50 and the rotating body 60 at this time. The distance between the friction material 50 and the rotating body 60 can be expressed, for example, as the shortest distance between the end face of the friction material 50 facing the rotating body 60 and the end face of the rotating body 60 facing the friction material 50. The initial position of the friction material 50 is defined as the position of the end of the friction material 50 attached to the output shaft 34 when the pressing mechanism 33 has stopped pressing.

[0020] When the mechanical brake device 30 starts operating, specifically when the motor 31 is driven and rotates in the forward direction by power supplied from the brake control device 1, the pressing mechanism 33 moves the output shaft 34 toward the rotating body 60 in accordance with the rotation of the motor 31. As a result, the friction material 50 attached to the end of the output shaft 34 is pushed toward the rotating body 60. Consequently, as shown in Figure 3, the friction material 50 moves to a position where it contacts the rotating body 60 and is pressed against the rotating body 60 by the pressing mechanism 33.

[0021] As described above, when the friction material 50 is repeatedly pressed against the rotating body 60, the friction material 50 wears down and becomes thinner. As a result, as shown in Figure 4, the distance between the friction material 50 and the rotating body 60 when the pressing mechanism 33 has stopped pressing becomes wider than in Figure 2. In Figure 4, let W2 be the distance between the friction material 50 and the rotating body 60 when the pressing mechanism 33 has stopped pressing. In this case, the relationship W2 > W1 holds true.

[0022] The gap adjustment mechanism 36 maintains the distance between the friction material 50 and the rotating body 60 within a target range when the pressing mechanism 33 has stopped pressing, by performing a mechanical operation to bring the friction material 50 closer to the rotating body 60. The target range is the range of values ​​that the distance between the friction material 50 and the rotating body 60 can take in order to obtain the responsiveness required by the mechanical brake device 30. The gap adjustment mechanism 36 is an existing mechanism, for example, the gap adjustment mechanism disclosed in Patent Document 1. Specifically, the gap adjustment mechanism 36 has a ratchet that rotates in conjunction with the movement of the output shaft 34 when the friction material 50 moves away from the rotating body 60, and stops rotating when the output shaft 34 moves when the friction material 50 approaches the rotating body 60.

[0023] When the friction material 50 is worn, the distance the output shaft 34 travels from the state in which the friction material 50 is in contact with the rotating body 60 as shown in Figure 5 back to the state in Figure 4 when the brake is released is greater than the distance the output shaft 34 travels when returning from the state in Figure 3 back to the state in Figure 2. In other words, the distance the worn friction material 50 travels from the position in Figure 5 where it is in contact with the rotating body 60 back to its initial position is greater than the distance the unworn friction material 50 travels from the position in Figure 3 where it is in contact with the rotating body 60 back to its initial position.

[0024] When the rotation angle of the ratchet corresponding to the movement of the output shaft 34 as the friction material 50 separates from the rotating body 60 and returns to its initial position exceeds a threshold value corresponding to the number of teeth on the ratchet, the teeth of the ratchet that engage with the retaining member 35 shift. The threshold value is, for example, the angle obtained by dividing 360 degrees by the number of teeth on the ratchet. As the teeth of the ratchet that engage with the retaining member 35 shift, the positions of the output shaft 34 and the friction material 50 approach the rotating body 60 when the pressing mechanism 33 has stopped pressing. In other words, the initial position of the friction material 50 approaches the rotating body 60.

[0025] As described above, the gap adjustment mechanism 36 performs a mechanical action that brings the friction material 50 attached to the output shaft 34 closer to the rotating body 60 when the ratchet teeth are misaligned, so that the gap between the friction material 50 and the rotating body 60 becomes narrower than the state in Figure 4, as shown in Figure 6. In Figure 6, let W3 be the gap between the friction material 50 and the rotating body 60 in the stopped state when the pressing mechanism 33 has stopped pressing. At this time, the gap W3 is about the same size as the gap W1. As a result, the gap between the friction material 50 and the rotating body 60 in the stopped state when the pressing mechanism 33 has stopped pressing is maintained within the target range, thereby suppressing a decrease in the responsiveness of the mechanical brake device 30.

[0026] The load cell 37 measures the pressing force, which is the force with which the pressing mechanism 33 presses the friction material 50 against the rotating body 60, and sends the measurement result to the target machine brake force determination unit 12 of the brake control device 1.

[0027] An encoder 38 is provided for each motor 31 and outputs a pulse signal corresponding to the rotation of the motor 31 to the speed control unit 14 of the brake control unit 13 and the discrimination unit 19 of the estimation device 18, which are included in the brake control device 1.

[0028] The brake control device 1 that controls the mechanical brake device 30 having the above configuration will be described below. The operating unit 41 shown in Figure 1 has a master controller that outputs a brake command indicating deceleration to the target brake force determination unit 11. The master controller outputs a brake command indicating deceleration corresponding to the notch in response to the operator's brake operation to the target brake force determination unit 11.

[0029] The target braking force determination unit 11 determines the target braking force for each vehicle or bogie from the deceleration indicated by the brake command that instructs the deceleration of the railway vehicle. For example, the target braking force determination unit 11 obtains the weight of the vehicle from a load-sensing device (not shown) and determines the target braking force for each vehicle by multiplying the weight of the vehicle by the deceleration indicated by the brake command. The target braking force determination unit 11 sends the determined target braking force to the target mechanical braking force determination unit 12.

[0030] The target mechanical braking force determination unit 12 determines the target mechanical braking force, which is the target value of the mechanical braking force provided by each mechanical braking device 30, from the target braking force. For example, the target mechanical braking force determination unit 12 determines the target mechanical braking force of the mechanical braking device 30 provided for each wheel from the target braking force for each vehicle. The target mechanical braking force determination unit 12 obtains the pressing force of the mechanical braking device 30 from the load cell 37 of the mechanical braking device 30 and determines the actual mechanical braking force, which corresponds to the mechanical braking force that actually occurs. The target mechanical braking force determination unit 12 adjusts the value of the target mechanical braking force by performing feedback control based on the actual mechanical braking force and sends the adjusted target mechanical braking force to the brake control unit 13.

[0031] The brake control unit 13 includes a speed control unit 14 that determines the target torque of the motor 31 from the target mechanical braking force, a torque control unit 15 that generates a PWM (Pulse Width Modulation) signal to obtain the target torque from the target torque and the actual torque of the motor 31, and outputs the PWM signal, and a power conversion circuit 16 that converts the power supplied from the power supply unit 42 into power to be supplied to the motor 31 of the mechanical brake device 30.

[0032] The speed control unit 14 obtains the target mechanical braking force from the target mechanical braking force determination unit 12. The speed control unit 14 determines the number of pulses per unit time from the pulse signal output by the encoder 38 of the mechanical braking device 30. The speed control unit 14 determines the rotational speed (in rpm) of the motor 31 per unit time from the resolution of the encoder 38 and the number of pulses per unit time. The speed control unit 14 determines the target pressing force, which is the force with which the mechanical braking device 30 presses the friction material 50 against the rotating body 60, from the target mechanical braking force.

[0033] The speed control unit 14 determines the target torque, which is the target value of the motor 31's torque, from the target pressing force and the parameters of the mechanical brake device 30. The parameters of the mechanical brake device 30 are used to convert the pressing force into the torque of the motor 31. The speed control unit 14 is assumed to have prior information about the parameters of the mechanical brake device 30. In order to gradually increase the rotation speed of the motor 31, the speed control unit 14 adjusts the target torque determined as described above and outputs the adjusted target torque to the torque control unit 15.

[0034] The torque control unit 15 obtains the target torque of the motor 31 from the speed control unit 14 and obtains the measured output current of the power conversion circuit 16 from the current sensor 17. Specifically, the torque control unit 15 obtains the measured U-phase current and V-phase current from the current sensor 17 and determines the value of the W-phase current from the measured U-phase and V-phase currents. The torque control unit 15 determines the actual torque of the motor 31 from the U-phase current, V-phase current, and W-phase current. The torque control unit 15 performs feedback control based on the target torque and the actual torque to generate a PWM signal to obtain the target torque. The torque control unit 15 outputs the PWM signal to each of the multiple switching elements of the power conversion circuit 16.

[0035] The power conversion circuit 16 has multiple switching elements controlled by a PWM signal supplied from the torque control unit 15. Through the switching operation of the multiple switching elements, the power conversion circuit 16 converts the DC power supplied from the power supply unit 42 into three-phase AC power, and supplies the three-phase AC power to the motor 31 of the mechanical brake device 30.

[0036] The power supply unit 42 converts the power supplied from a current collector (not shown) into power for supply to the power conversion circuit 16, and outputs the converted power to the power conversion circuit 16. The power supply unit 42 receives DC power from a current collector that obtains power from a substation via a power supply line, and includes an inverter that converts DC power to AC power, and a rectifier circuit that rectifies AC power back to DC power.

[0037] The estimation device 18 includes a determination unit 19 that determines whether or not a mechanical operation to bring the friction material 50 closer to the rotating body 60 has been performed by the gap adjustment mechanism 36, based on the amount of rotation of the motor 31 from the time the motor 31 starts rotating until the friction material 50 comes into contact with the rotating body 60, and an estimation unit 20 that estimates the amount of wear of the friction material 50 from the number of times the mechanical operation of the gap adjustment mechanism 36 has been performed. The amount of rotation at startup indicates, for example, the number of times the motor 31 has rotated from the time the motor 31 starts rotating until the friction material 50 comes into contact with the rotating body 60.

[0038] The estimation device 18 in the brake control device 1 having the above configuration determines the number of mechanical movements by the gap adjustment mechanism 36 to bring the friction material 50 closer to the rotating body 60 from the amount of rotation of the motor 31 at startup, and estimates the amount of wear of the friction material 50 in the mechanical brake device 30 from the number of mechanical movements by the gap adjustment mechanism 36 to bring the friction material 50 closer to the rotating body 60. As a result, it is not necessary to provide a rotation sensor in the mechanical brake device 30, and it is possible to estimate the amount of wear of the friction material 50 with a simple configuration.

[0039] Figure 7 shows the hardware configuration of the brake control device 1 having the above configuration. The brake control device 1 comprises a processor 81, a memory 82, and an interface 83. The processor 81, memory 82, and interface 83 are connected to each other by a bus 80. The functions of each part of the brake control device 1 are realized by software, firmware, or a combination of software and firmware. The software and firmware are written as programs and stored in the memory 82. The functions of each part described above are realized by the processor 81 reading and executing the programs stored in the memory 82. In other words, the memory 82 stores programs for executing the processing of each part of the brake control device 1.

[0040] Memory 82 includes, for example, non-volatile or volatile semiconductor memories such as RAM (Random Access Memory), ROM (Read-Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable and Programmable Read-Only Memory), magnetic disks, flexible disks, optical disks, compact disks, minidiscs, DVDs (Digital Versatile Discs), etc.

[0041] The brake control device 1 is connected to the operating unit 41, the power supply unit 42, and the mechanical brake device 30 via interface 83. Interface 83 has one or more interface modules conforming to standards, depending on the connection destination.

[0042] The process by which the brake control device 1 having the above configuration estimates the amount of wear of the friction material 50 will be explained with reference to Figure 8. The estimation device 18 provided in the brake control device 1 starts the process shown in Figure 8 when the railway vehicle starts operating and the brakes are released. Specifically, when the lifting switch that brings the pantograph, which is an example of a current collection device, into contact with the overhead wire, which is an example of a power supply line, is operated and the brakes are released, the estimation device 18 starts the process shown in Figure 8.

[0043] The discrimination unit 19 determines from the pulse signal output by the encoder 38 whether or not the motor 31 has started rotating (step S11). More specifically, the discrimination unit 19 determines whether or not the amplitude of the pulse signal is greater than or equal to a start threshold that indicates the motor 31 has started operating. The start threshold is determined, for example, according to the values ​​that the amplitude of the pulse signal can take immediately after the motor 31 starts rotating.

[0044] If the amplitude of the pulse signal is less than the starting threshold and the motor 31 is deemed to have stopped rotating (step S11; No), the process in step S11 is repeated.

[0045] When the amplitude of the pulse signal exceeds the starting threshold, and it is determined that the motor 31 has started rotating (step S 11; Yes), the discrimination unit 19 integrates the number of pulses in the pulse signal (step S12).

[0046] The discrimination unit 19 determines whether or not the friction material 50 has come into contact with the rotating body 60 (step S13). When the friction material 50 comes into contact with the rotating body 60, the rotational speed of the motor 31 per unit time decreases sharply, so the discrimination unit 19 determines whether or not the friction material 50 has come into contact with the rotating body 60 based on the rotational speed of the motor 31 per unit time obtained from the speed control unit 14.

[0047] The discrimination unit 19 detects the timing when the friction material 50 comes into contact with the rotating body 60 from the pulse signal. More specifically, the discrimination unit 19 repeatedly obtains the rotational speed per unit time of the motor 31 from the speed control unit 14 and stores the rotational speed per unit time of the motor 31 in a storage device (not shown). The discrimination unit 19 determines the amount of decrease in the rotational speed per unit time of the motor 31 from the rotational speed per unit time of the motor 31 obtained from the speed control unit 14 and the rotational speed per unit time of the motor 31 that was previously obtained from the speed control unit 14 and stored.

[0048] If the decrease in the rotational speed of the motor 31 per unit time is within the target variation range, the discrimination unit 19 determines that the friction material 50 is separated from the rotating body 60 (step S13; No), and the above process is repeated from step S12. The target variation range is set to a range that includes the values ​​that the variation in the rotational speed of the motor 31 can take when the friction material 50 can be considered separated from the rotating body 60.

[0049] If the decrease in the rotational speed of motor 31 per unit time is not within the target fluctuation range, in other words, if the rotational speed of motor 31 per unit time decreases rapidly, the discrimination unit 19 determines that the friction material 50 has come into contact with the rotating body 60 (step S13; Yes), and from the resolution of the encoder 38 and the integrated value of the number of pulses, it determines the starting rotation amount, which is the number of times motor 31 rotates from the time motor 31 starts rotating to the time friction material 50 comes into contact with the rotating body 60 (step S14).

[0050] The discrimination unit 19 determines whether or not the gap adjustment mechanism 36 is performing mechanical operation based on the amount of rotation at startup determined in step S14 (step S15). As shown in Figure 9, the amount of rotation at startup increases as the amount of wear on the friction material 50 increases due to the operation of the mechanical brake device 30, and decreases when the gap adjustment mechanism 36 adjusts the gap between the friction material 50 and the rotating body 60 by performing a mechanical operation that brings the friction material 50 closer to the rotating body 60.

[0051] The horizontal axis of Figure 9 shows the estimation timing at which the estimation device 18 estimates the amount of wear of the friction material 50, specifically, the timing at which the estimation device 18 starts the wear amount estimation process shown in Figure 8. The vertical axis of Figure 9 shows the starting rotation amount obtained in step S14 of the wear amount estimation process.

[0052] For example, as shown in Figure 2, the estimated timing T1 corresponds to the state where the amount of wear of the friction material 50 is sufficiently small and the distance between the friction material 50 and the rotating body 60 is W1. The starting rotation amount at this time is R1. Specifically, R1 is the number of rotations the motor 31 makes from the state in Figure 2 where the brake is released to the state in Figure 3 where the friction material 50 contacts the rotating body 60. After the estimated timing T1, the timing at which the estimation device 18 starts the wear amount estimation process is defined as the estimated timing T1'. The starting rotation amount at the estimated timing T1' is defined as R1'. As the wear of the friction material 50 increases the distance between the friction material 50 and the rotating body 60, the starting rotation amount R1' becomes larger than the starting rotation amount R1.

[0053] As shown in Figure 4, the estimated timing T2 corresponds to the state where the friction material 50 is worn down and the distance between the friction material 50 and the rotating body 60 is W2. The starting rotation amount at this time is R2. Specifically, R2 is the number of rotations the motor 31 makes from the state in Figure 4 where the brake is released to the state in Figure 5 where the friction material 50 contacts the rotating body 60.

[0054] When the brake is released in the state shown in Figure 5, the power conversion circuit 16 of the brake control unit 13 of the brake control device 1 stops supplying power to the motor 31. When the power supply to the motor 31 is stopped, the rotation of the motor 31 stops, and the pressing mechanism 33 stops pressing the friction material 50 against the rotating body 60. After the motor 31 stops rotating, when the motor 31 rotates in the reverse direction, the output shaft 34 moves away from the rotating body 60, resulting in the state shown in Figure 4. When the rotation angle of the ratchet corresponding to the movement of the output shaft 34 when returning from the state shown in Figure 5 to the state shown in Figure 4 exceeds a threshold, the teeth of the ratchet that engage with the holding member 35 shift, and the position of the output shaft 34 in the state when the pressing mechanism 33 has stopped pressing approaches the rotating body 60. As a result, as shown in Figure 6, the position of the friction material 50 in the state when the pressing mechanism 33 has stopped pressing approaches the rotating body 60.

[0055] As shown in Figure 6, the gap adjustment mechanism 36 performs a mechanical operation to bring the friction material 50 closer to the rotating body 60, and the estimated timing T3 corresponds to the state in which the gap between the friction material 50 and the rotating body 60 has narrowed to W3. The starting rotation amount at this time is R3. Specifically, R3 is the number of times the motor 31 rotates from the state in Figure 6 to the state in Figure 5. As shown in Figure 9, the starting rotation amount R3 is smaller than the starting rotation amount R2. As described above, the starting rotation amount immediately after the gap adjustment mechanism 36 performs the mechanical operation to bring the friction material 50 closer to the rotating body 60 is smaller than the starting rotation amount immediately before the gap adjustment mechanism 36 performs the mechanical operation to bring the friction material 50 closer to the rotating body 60.

[0056] Using an existing gap adjustment mechanism 36 that maintains the distance between the friction material 50 and the rotating body 60 within a target range, the estimation device 18 estimates the amount of wear on the friction material 50. Specifically, as shown in Figure 8, the discrimination unit 19 determines whether or not the gap adjustment mechanism 36 performed a mechanical operation to bring the friction material 50 closer to the rotating body 60, based on the change in the amount of rotation at startup obtained in step S14, from the change in the amount of rotation at startup over time. In detail, the discrimination unit 19 stores the amount of rotation at startup obtained in step S14 in a storage device (not shown). The discrimination unit 19 determines whether or not the gap adjustment mechanism 36 performed a mechanical operation by comparing the amount of rotation at startup obtained in step S14 with the amount of rotation at startup obtained at the estimation timing immediately preceding the amount of rotation at startup, in other words, with the amount of rotation at startup obtained in step S14 when the wear amount estimation process shown in Figure 8 was performed most recently.

[0057] If the absolute value of the decrease in the starting rotation amount, relative to the immediately preceding starting rotation amount, is less than or equal to the decrease threshold, it can be assumed that the gap adjustment mechanism 36 has not performed the mechanical action of bringing the friction material 50 closer to the rotating body 60. If the absolute value of the decrease in the starting rotation amount, relative to the immediately preceding starting rotation amount, is greater than the decrease threshold, it can be assumed that the gap adjustment mechanism 36 has performed the mechanical action of bringing the friction material 50 closer to the rotating body 60. The discrimination unit 19 sends the determination result of whether or not the absolute value of the decrease in the starting rotation amount is greater than or equal to the decrease threshold to the estimation unit 20. The decrease threshold is determined according to the number of rotations of the motor 31 corresponding to the amount by which the output shaft 34 moved toward the rotating body 60 when the gap adjustment mechanism 36 performs the mechanical action of bringing the friction material 50 closer to the rotating body 60.

[0058] If the discrimination unit 19 determines that the absolute value of the decrease in rotational amount at startup is greater than the decrease threshold, and therefore the gap adjustment mechanism 36 has performed a mechanical operation to bring the friction material 50 closer to the rotating body 60 (step S15; Yes), the estimation unit 20 estimates the amount of wear of the friction material 50 from the number of times the gap adjustment mechanism 36 has performed the mechanical operation to bring the friction material 50 closer to the rotating body 60 and the distance the output shaft 34 moves in one such mechanical operation of the gap adjustment mechanism 36, in other words, the distance the friction material 50 moves (step S16). The estimation unit 20 is assumed to have prior information about the distance the output shaft 34 moves when the gap adjustment mechanism 36 performs one mechanical operation to bring the friction material 50 closer to the rotating body 60.

[0059] The estimation unit 20 accumulates the number of times the gap adjustment mechanism 36 has performed a mechanical action to bring the friction material 50 closer to the rotating body 60, according to the discrimination result obtained from the discrimination unit 19. The estimation unit 20 estimates the amount of wear (in millimeters) of the friction material 50 by multiplying the accumulated number of mechanical actions performed by the gap adjustment mechanism 36 to bring the friction material 50 closer to the rotating body 60 by the distance the friction material 50 moves in one such mechanical action of the gap adjustment mechanism 36. The amount of wear of the friction material 50 is the total amount of wear that has occurred since the friction material 50 was attached to the mechanical brake device 30 and the mechanical brake device 30 began operation. The estimation unit 20 sends the amount of wear of the friction material 50 to an external device (not shown).

[0060] If the discrimination unit 19 determines that the absolute value of the decrease in rotation amount at startup is less than or equal to the decrease threshold, and therefore the gap adjustment mechanism 36 is not performing the mechanical action of bringing the friction material 50 closer to the rotating body 60 (step S15; No), the estimation unit 20 does not perform the process in step S16.

[0061] When the process in step S16 is completed, or when the discrimination unit 19 determines that the gap adjustment mechanism 36 is not performing the mechanical action of bringing the friction material 50 closer to the rotating body 60 because the absolute value of the decrease in the amount of rotation at startup is less than or equal to the decrease threshold (step S15; No), the estimation device 18 terminates the estimation process. The estimation device 18 repeats the estimation process shown in Figure 8 at a predetermined estimation timing, for example, every day when the railway vehicle starts operation. In other words, the discrimination unit 19 of the estimation device 18 determines whether or not the gap adjustment mechanism 36 is performing the mechanical action from the amount of rotation at startup when the mechanical brake device 30 is first operated after the railway vehicle starts operation.

[0062] As described above, the estimation device 18 provided in the brake control device 1 according to Embodiment 1 determines whether or not the gap adjustment mechanism 36 has performed a mechanical action to bring the friction material 50 closer to the rotating body 60, based on the starting rotation amount, which is the number of rotations of the motor 31 from the time the motor 31 starts rotating until the friction material 50 comes into contact with the rotating body 60. The estimation device 18 estimates the amount of wear of the friction material 50 from the number of times the gap adjustment mechanism 36 has performed a mechanical action to bring the friction material 50 closer to the rotating body 60. For this reason, there is no need to provide a rotation sensor in the mechanical brake device 30, and it is possible to estimate the amount of wear of the friction material 50 of the mechanical brake device 30 with a simple configuration.

[0063] (Embodiment 2) The configuration of the estimation device 18 is not limited to the example described above. The estimation device 18 provided in the brake control device 2 shown in Figure 10 includes, in addition to the configuration of the estimation device 18 provided in the brake control device 1 according to Embodiment 1, an output unit 21 that outputs a warning when the amount of wear of the friction material 50 exceeds a wear threshold. The estimation device 18 provided in the brake control device 2 according to Embodiment 2 will be described below, focusing on the differences from Embodiment 1.

[0064] The discrimination unit 19 of the estimation device 18 detects the timing when the motor 31 started rotating from the pulse signal output by the encoder 38, similar to the first embodiment. Unlike the first embodiment, the discrimination unit 19 detects the timing when the friction material 50 came into contact with the rotating body 60 from the current flowing through the motor 31.

[0065] When the amount of wear of the friction material 50 estimated by the estimation unit 20 exceeds the wear threshold, the output unit 21 outputs a warning to a display device, for example, installed in the driver's cab, indicating that the amount of wear of the friction material 50 exceeds the wear threshold.

[0066] Similar to Embodiment 1, the estimation device 18 starts the process shown in Figure 11 when the railway vehicle starts operating. The steps S11 to S12 of the estimation process shown in Figure 11 are the same as the steps S11 to S12 performed by the estimation device 18 provided in the brake control device 1 according to Embodiment 1 shown in Figure 8. When step S12 is completed, the discrimination unit 19 obtains the measured value of the U-phase current from the current sensor 17 and determines whether the friction material 50 has come into contact with the rotating body 60 based on whether the amplitude of the U-phase current is greater than or equal to the current threshold (step S17).

[0067] When the friction material 50 comes into contact with the rotating body 60, the rotation of the motor 31 is hindered by the contact between the friction material 50 and the rotating body 60, so the current supplied to the motor 31 to drive the motor 31 increases. Therefore, the discrimination unit 19 obtains a measured value of the U-phase current from the current sensor 17 and determines whether the amplitude of the U-phase current is greater than or equal to the current threshold. The current threshold should be set to a value greater than the value that the amplitude of the U-phase current can take when the friction material 50 and the rotating body 60 are separated. If the amplitude of the U-phase current is less than the current threshold, the discrimination unit 19 determines that the friction material 50 is separated from the rotating body 60 (step S17; No), and the above process is repeated from step S12. If the amplitude of the U-phase current is greater than or equal to the current threshold, the discrimination unit 19 determines that the friction material 50 has come into contact with the rotating body 60 (step S17; Yes), and the process in step S14 is performed. The estimation process steps S14 to S16 shown in Figure 11 are the same as the estimation process steps S14 to S16 performed by the estimation device 18 provided in the brake control device 1 according to Embodiment 1 shown in Figure 8.

[0068] The output unit 21 obtains the amount of wear of the friction material 50 estimated in step S16 from the estimation unit 20. The output unit 21 determines whether the amount of wear of the friction material 50 is greater than or equal to the wear threshold (step S18). If the amount of wear of the friction material 50 is greater than or equal to the wear threshold (step S18; Yes), the output unit 21 outputs the determination result indicating that the amount of wear of the friction material 50 is greater than or equal to the wear threshold to the display device provided in the driver's cab (step S19). The wear threshold can be determined according to the thickness of the friction material 50 at the start of use. For example, the wear threshold can be set to half the thickness of the friction material 50 at the start of use. If the amount of wear of the friction material 50 is less than the wear threshold (step S18; No), the output unit 21 does not perform the process in step S19.

[0069] When the processing in step S19 is completed or the output unit 21 determines that the amount of wear of the friction material 50 is less than the wear threshold (step S18; No), the estimation device 18 terminates the estimation process. The estimation device 18 performs the estimation process shown in Figure 11, for example, every day when the railway vehicle starts operation. In other words, the discrimination unit 19 of the estimation device 18 determines whether or not there is mechanical operation of the gap adjustment mechanism 36 from the amount of rotation at startup when the mechanical brake device 30 is operated for the first time after the railway vehicle starts operation.

[0070] As described above, the estimation device 18 provided in the brake control device 2 according to Embodiment 2 determines whether or not the gap adjustment mechanism 36 is mechanically operating based on the amount of rotation at startup, estimates the amount of wear of the friction material 50 from the number of mechanical operations of the gap adjustment mechanism 36, and outputs a determination result indicating that the amount of wear of the friction material 50 is above the wear threshold if the amount of wear of the friction material 50 is above the wear threshold. This makes it possible to prompt maintenance work on the friction material 50.

[0071] This disclosure is not limited to the embodiments described above. The timing at which the estimation device 18 performs the estimation process is not limited to the examples described above and is arbitrary. For example, the estimation device 18 may perform the estimation process when the railway vehicle returns to the depot and the mechanical brake system 30 operates. As another example, the estimation device 18 may perform the estimation process when the mechanical brake system 30 operates immediately after a predetermined timing, such as every week or every month.

[0072] The method by which the discrimination unit 19 detects the timing when the motor 31 starts rotating and the timing when the friction material 50 comes into contact with the rotating body 60 is not limited to the examples described above. For example, the discrimination unit 19 may acquire a brake command input from the driver's cab to the target brake force determination unit 11 and detect the timing at which the brake command is acquired as the timing when the motor 31 starts rotating. As another example, the discrimination unit 19 may detect the timing at which the target machine brake force output by the target machine brake force determination unit 12 becomes greater than 0 as the timing when the motor 31 starts rotating.

[0073] As another example, the discrimination unit 19 may detect the timing when the amplitude of the current flowing through the motor 31 becomes greater than 0 as the timing when the motor 31 starts to rotate. When the discrimination unit 19 detects the timing when the motor 31 starts to rotate and the timing when the friction material 50 comes into contact with the rotating body 60 based on the current flowing through the motor 31, the mechanical brake device 30 does not need to be equipped with an encoder 38. In this case, the speed control unit 14 only needs to estimate the position and speed of the rotor of the motor 31 from the current flowing through the motor 31 and the voltage applied to the motor 31.

[0074] The discrimination unit 19 may determine whether or not mechanical operation of the gap adjustment mechanism 36 has occurred based on the ratio of the starting rotation amount to the starting rotation amount immediately preceding it.

[0075] When the friction material 50 is a brake shoe and the rotating body 60 is a wheel, the discrimination unit 19 may, for example, obtain information from the driver's cab indicating whether or not the wheel has been truing, and may determine that no mechanical operation of the gap adjustment mechanism 36 occurs during the first operation of the mechanical brake device 30 after the wheel has been truing. When the wheel, which is the rotating body 60, is truing, the wheel diameter decreases, and the gap between the friction material 50 and the rotating body 60 widens. Therefore, if the mechanical brake device 30 is operated immediately after the wheel has been truing, the distance the output shaft 34 travels increases when the friction material 50 and the rotating body 60 are in contact and the pressing mechanism 33 stops its pressing operation, causing the gap adjustment mechanism 36 to perform a mechanical operation. Since this mechanical operation of the gap adjustment mechanism 36 is due to wheel truing and not wear of the friction material 50, the discrimination unit 19 determines that no mechanical operation of the gap adjustment mechanism 36 occurs during the first operation of the mechanical brake device 30 after the wheel has been truing. This improves the accuracy of the estimation of the amount of wear of the friction material 50 by the estimation device 18.

[0076] In embodiments 1 and 2, the amount of rotation at startup is expressed as the number of rotations of the motor 31 from the time the motor 31 starts rotating until the friction material 50 contacts the rotating body 60. However, it may also be expressed as the rotation angle, rotation distance, etc., of the motor 31 during the period from the time the motor 31 starts rotating until the friction material 50 contacts the rotating body 60.

[0077] In embodiments 1 and 2, the amount of wear estimated by the estimation unit 20 is expressed as the thickness of the worn friction material 50 (in millimeters), but it may also be expressed as the ratio of the thickness of the worn friction material 50 to the thickness of the friction material 50 at the start of use.

[0078] The output unit 21 may output the discrimination result to the display device regardless of the discrimination result. More specifically, when the amount of wear of the friction material 50 is less than the wear threshold, the output unit 21 may output a discrimination result to the display device indicating that the amount of wear of the friction material 50 is less than the wear threshold.

[0079] The configuration of the mechanical brake device 30 is not limited to the example described above. For example, the clearance adjustment mechanism 36 is not limited to the configuration described above, and can be any configuration that can maintain the distance between the friction material 50 and the rotating body 60 within the target range.

[0080] As another example, as shown in Figure 12, the mechanical brake device 30 may include a power assist mechanism 39 in addition to the pressing mechanism 33. In this case, the pressing mechanism 33 is a rotation-to-linear motion conversion mechanism that slides with the rotational force of the motor 31 and presses the point of force application 39a of the power assist mechanism 39.

[0081] The force amplification mechanism 39 is a lever mechanism that amplifies the force applied to the point of effort 39a from the pressing mechanism 33 and outputs it from the point of application 39d. In detail, the force amplification mechanism 39 has an arm 39c that is rotatable around a fulcrum 39b. A holding member 40 is attached to the point of application 39d, which is located at the end of the arm 39c opposite to the point of effort 39a relative to the fulcrum 39b. The holding member 40 holds the output shaft 34.

[0082] As shown in Figure 13, when force is applied from the pressing mechanism 33 to the point of force application 39a, the arm 39c rotates around the fulcrum 39b, and the output shaft 34, held by the holding member 40 attached to the point of application 39d of the arm 39c, moves toward the rotating body 60. As a result, the friction material 50 is pressed against the rotating body 60. When the friction material 50 wears down due to the operation of the mechanical brake device 30, the gap adjustment mechanism 36 performs a mechanical operation, similar to embodiments 1 and 2, to maintain the distance between the friction material 50 and the rotating body 60 within the target range.

[0083] The power assist mechanism 39 is not limited to a lever mechanism; for example, it may be a toggle mechanism, a link mechanism, or the like.

[0084] The estimation device 18 may be a device independent of the brake control device 1. In this case, the estimation device 18 can be implemented with the hardware configuration shown in Figure 7, specifically, a processor 81, memory 82, and interface 83 independent of the brake control device 1.

[0085] The estimation device 18 may be implemented as a function of the brake control devices 1 and 2, as shown in Embodiments 1 and 2. In this case, the estimation device 18 may be implemented by a processor 81, memory 82, and interface 83 common to the target brake force determination unit 11, the target mechanical brake force determination unit 12, and the brake control unit 13.

[0086] The estimation device 18 is not limited to mechanical brake systems 30 mounted on railway vehicles, but may also estimate the friction material 50 of a mechanical brake system 30 mounted on a streetcar. The estimation device 18 may also estimate the friction material 50 of a mechanical brake system 30 mounted on a railway vehicle that decelerates by at least one of mechanical braking force and electric braking force.

[0087] The brake command output by the control unit 41 is not limited to a service brake command, but may also include emergency brake commands, safety brake commands, parking brake commands, etc.

[0088] The target braking force determination unit 11 is not limited to the operation unit 41, but may also acquire braking commands from a train information management system, an ATS (Automatic Train Stop) device, etc.

[0089] The central part of the control processing unit, which includes a processor 81, memory 82, and interface 83, can be implemented using a standard computer system rather than a dedicated system. For example, a computer program for performing the above-described operations may be stored on a computer-readable recording medium (flexible disk, CD-ROM (Compact Disc-Read Only Memory), DVD-ROM (Digital Versatile Disc-Read Only Memory), etc.) and distributed, and the brake control devices 1 and 2 that perform the above-described operations may be implemented by installing the computer program on a computer. Alternatively, the computer program may be stored on a storage device of a server device on a communication network, and the brake control devices 1 and 2 may be implemented by downloading it from a standard computer system.

[0090] If the functions of the brake control devices 1 and 2 are realized through a division of labor between the OS (Operating System) and application programs, or through collaboration between the OS and application programs, then only the application program portion may be stored on a recording medium, storage device, etc.

[0091] It is also possible to superimpose a computer program onto a carrier wave and distribute it via a communication network. For example, the computer program could be posted on a bulletin board system (BBS) on a communication network and distributed via the network. Then, the above-described process could be executed by starting this computer program and running it under the control of the OS, just like any other application program.

[0092] The hardware configuration of the brake control devices 1 and 2 is not limited to the example described above. As an example, as shown in Figure 14, the brake control devices 1 and 2 may be implemented by a processing circuit 84. The processing circuit 84 is connected to the operating unit 41, the power supply unit 42, and the mechanical brake device 30 via an interface circuit 85. If the processing circuit 84 is dedicated hardware, it may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof. Each part of the brake control devices 1 and 2 may be implemented by an individual processing circuit 84, or each part of the brake control devices 1 and 2 may be implemented by a common processing circuit 84.

[0093] Some functions of the brake control devices 1 and 2 may be implemented by dedicated hardware, while other functions may be implemented by software or firmware. For example, in the brake control devices 1 and 2, the brake control unit 13 may be implemented by the processing circuit 84 shown in Figure 14, and the target brake force determination unit 11 and the target mechanical brake force determination unit 12 may be implemented by the processor 81 shown in Figure 7 reading and executing a program stored in memory 82.

[0094] This disclosure allows for various embodiments and modifications without departing from the broad spirit and scope of this disclosure. Furthermore, the embodiments described above are for illustrative purposes only and do not limit the scope of this disclosure. In other words, the scope of this disclosure is indicated by the claims, not by the embodiments. Various modifications made within the scope of the claims and the equivalent significance of the disclosure are considered to be within the scope of this disclosure. [Explanation of Symbols]

[0095] 1,2 Brake control device, 11 Target brake force determination unit, 12 Target mechanical brake force determination unit, 13 Brake control unit, 14 Speed ​​control unit, 15 Torque control unit, 16 Power conversion circuit, 17 Current sensor, 18 Estimation device, 19 Discrimination unit, 20 Estimation unit, 21 Output unit, 30 Mechanical brake device, 31 Motor, 31a Drive shaft, 32 Reducer, 33 Pressing mechanism, 34 Output shaft, 35,40 Holding member, 36 Gap adjustment mechanism, 37 Load cell, 38 Encoder, 39 Power assist mechanism, 39a Point of force application, 39b Pivot point, 39c Arm, 39d Point of application, 41 Operating unit, 42 Power supply unit, 50 Friction material, 60 Rotating body, 80 Bus, 81 Processor, 82 Memory, 83 Interface, 84 Processing circuit, 85 Interface circuit, 100 Brake control system, W1, W2, W3 interval.

Claims

1. An estimation device for estimating the amount of wear of a friction material in a mechanical brake system, comprising: a pressing mechanism that generates a mechanical braking force by pressing a friction material against a rotating body that rotates when a vehicle is in motion using the rotational force of a motor; and a gap adjustment mechanism that maintains the distance between the friction material and the rotating body within a target range when the pressing mechanism has stopped pressing, by performing a mechanical operation to bring the friction material closer to the rotating body; A determination unit that determines whether or not the mechanical operation of the gap adjustment mechanism is performed based on the starting rotation amount, which is the amount of rotation of the motor from the time the motor starts rotating until the friction material comes into contact with the rotating body, An estimation unit that estimates the amount of wear of the friction material from the number of times the mechanical operation of the gap adjustment mechanism that brings the friction material closer to the rotating body is performed, An estimation device equipped with the following features.

2. The determination unit determines the starting rotation amount from the integrated value of the number of pulses of the pulse signals output by the encoder provided for each motor from the timing when the motor starts rotating until the timing when the friction material comes into contact with the rotating body, and determines whether or not the mechanical operation of the gap adjustment mechanism is performed based on the determined starting rotation amount. The estimation device according to claim 1.

3. The discrimination unit detects from the pulse signal at least one of the timing when the motor started to rotate and the timing when the friction material came into contact with the rotating body. The estimation device according to claim 2.

4. The discrimination unit detects from the current flowing through the motor at least one of the timing when the motor started to rotate and the timing when the friction material came into contact with the rotating body. The estimation device according to any one of claims 1 to 3.

5. The discrimination unit detects the timing at which the motor started rotating from a brake command instructing the vehicle to decelerate or a target mechanical braking force which is a target value of the mechanical braking force applied by the mechanical braking device corresponding to the deceleration indicated by the brake command. The estimation device according to any one of claims 1 to 3.

6. The discrimination unit repeatedly determines the amount of rotation at startup and determines whether or not the mechanical operation of the gap adjustment mechanism is performed based on the change in the amount of rotation at startup over time. The estimation device according to any one of claims 1 to 3.

7. The discrimination unit repeatedly determines the amount of rotation at startup at predetermined estimated timings, and determines whether or not the mechanical operation of the gap adjustment mechanism is performed by comparing the amount of rotation at startup with the amount of rotation at startup determined at the estimated timing immediately preceding the estimated timing in which the amount of rotation at startup was determined. The estimation device according to claim 6.

8. The estimation unit estimates the amount of wear of the friction material from the number of times the mechanical operation of the gap adjustment mechanism has been performed and the distance the friction material moves due to one of the mechanical operations of the gap adjustment mechanism. The estimation device according to any one of claims 1 to 3.

9. An output unit determines whether the amount of wear of the friction material estimated by the estimation unit is equal to or greater than a wear threshold determined according to the thickness of the friction material at the start of use, and outputs the determination result. The estimation device according to any one of claims 1 to 3, further comprising:

10. Based on information indicating whether or not the rotating wheel has been machined, the discrimination unit determines that the mechanical operation of the gap adjustment mechanism has not occurred during the first operation of the mechanical brake device after the wheel has been machined. The estimation device according to any one of claims 1 to 3.

11. The discrimination unit determines, based on the amount of rotation at startup, whether or not the mechanical operation of the gap adjustment mechanism is performed when the mechanical brake device is first operated after the railway vehicle starts running. The estimation device according to any one of claims 1 to 3.

12. A brake control device for controlling a mechanical brake device comprising: a pressing mechanism that generates a mechanical braking force by pressing a friction material against a rotating body that rotates when a vehicle is in motion using the rotational force of a motor; and a gap adjustment mechanism that maintains the distance between the friction material and the rotating body within a target range when the pressing mechanism is stopped by performing a mechanical operation to bring the friction material closer to the rotating body, A target brake force determination unit that determines a target brake force from a brake command that instructs the vehicle to decelerate, A target mechanical braking force determination unit that determines the target mechanical braking force, which is the target value of the braking force by the mechanical braking device, from the aforementioned target braking force, A brake control unit that, from the aforementioned target mechanical braking force, determines the target torque of the motor that generates the power for the mechanical braking device to press the friction material against the rotating body, converts the power supplied from the power supply device into power to be supplied to the motor according to the target torque, and supplies the converted power to the motor, An estimation device according to any one of claims 1 to 3, A brake control device equipped with the following features.

13. A method for estimating the amount of wear of a friction material in a mechanical brake device, comprising: a pressing mechanism that generates a mechanical braking force by pressing a friction material against a rotating body that rotates when a vehicle is in motion using the rotational force of a motor; and a gap adjustment mechanism that maintains the distance between the friction material and the rotating body within a target range when the pressing mechanism has stopped pressing, by performing a mechanical operation to bring the friction material closer to the rotating body; The presence or absence of the mechanical operation of the gap adjustment mechanism is determined from the starting rotation amount, which is the amount of rotation of the motor from when the motor starts rotating until the friction material comes into contact with the rotating body. The amount of wear on the friction material is estimated from the number of times the mechanical operation of the gap adjustment mechanism, which brings the friction material closer to the rotating body, is performed. Estimation method.

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