Brake control device, brake control system, and brake control method

Abstract

A brake control device (1) comprises a discrimination unit (13) that discriminates whether a friction material and a rotating body are separated from each other, and a driving driver (14) that supplies a motor (31) of a mechanical brake device (30) with electric power corresponding to a target torque and a target rotation speed based on the target torque. When the friction material and the rotating body are separated from each other, the driving driver (14) sets, as the target torque, a value smaller than the torque of the motor (31) for pressing the friction material against the rotating body. When the friction material and the rotating body are not separated from each other, the driving driver (14) sets the torque of the motor (31) for obtaining a target mechanical braking force as the target torque.

Description

Brake control device, brake control system, and brake control method

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

[0002] Railway vehicles are equipped with mechanical brake devices that generate braking force by pressing friction material against a rotating body that rotates while the vehicle is running. Mechanical brake devices include electric brake devices that press friction material against the rotating body by sliding the output shaft of a rotary-to-linear motion conversion mechanism using the rotation of a motor.

[0003] An example of this type of mechanical brake device is disclosed in Patent Document 1. The brake device disclosed in Patent Document 1 includes an actuator that uses the rotation of a motor to advance a piston and press the brake pads against a disc rotor, and a controller that controls the actuator. When a braking force request is generated, the controller advances the piston at a first speed, and then decelerates the speed to a second speed lower than the first speed to advance the piston, thereby eliminating the clearance between the brake pads and the disc rotor.

[0004] Japanese Patent Application Laid-Open No. 2019-38302

[0005] In the mechanical brake device disclosed in Patent Document 1, increasing the motor output to improve responsiveness increases the amount of power consumed to drive the motor. On the other hand, reducing the amount of power consumed by the mechanical brake device in order to reduce the amount of power consumed by the railway vehicle reduces the responsiveness of the mechanical brake device.

[0006] The present disclosure has been made in consideration of the above-mentioned circumstances, and aims to provide a brake control device, a brake control system, and a brake control method that improve the responsiveness of a mechanical brake device and suppress an increase in power consumption.

[0007] In order to achieve the above object, the brake control device according to the present disclosure is a brake control device that controls a mechanical brake device that generates a mechanical brake force by pressing a friction material against a rotating body that rotates when a railway vehicle is traveling using the rotational force of a motor with adjustable torque and rotation speed, and includes a target brake force determination unit, a target mechanical brake force determination unit, a discrimination unit, and a drive driver. The target brake force determination unit calculates the target brake force from the deceleration indicated by a brake command that instructs the railway vehicle to decelerate. The target mechanical brake force determination unit calculates the target mechanical brake force, which is a target value for the brake force applied by the mechanical brake device, from the target brake force. The discrimination unit determines whether the friction material and the rotating body are separated. If the discrimination unit determines that the friction material and the rotating body are separated, the drive driver sets the target torque to a value smaller than the motor torque for pressing the friction material against the rotating body, and if the discrimination unit determines that the friction material and the rotating body are not separated, sets the motor torque for obtaining the target mechanical braking force as the target torque, and converts the power supplied from the power supply device into power to be supplied to the motor according to the target torque and the target rotation speed determined from the target torque based on the relationship characteristics between the motor torque and rotation speed, and supplies the converted power to the motor.

[0008] The brake control device according to the present disclosure controls the motor of the mechanical brake device based on a target torque corresponding to whether the friction material is separated from the rotating body and a target rotation speed corresponding to the target torque, thereby improving the responsiveness of the mechanical brake device and suppressing increases in power consumption.

[0009] FIG. 1 is a block diagram of a brake control system according to a first embodiment. FIG. 1 is a diagram showing a configuration of a mechanical brake device according to a first embodiment. FIG. 1 is a diagram showing a configuration of a mechanical brake device according to a first embodiment. FIG. 2 is a diagram showing a relationship between torque and rotation speed used by a brake control device according to a first embodiment to control a motor. FIG. 3 is a block diagram of a brake control system according to a second embodiment. FIG. 4 is a diagram showing an example of the operation of brake control processing performed by the brake control device according to the first embodiment. FIG. 5 is a diagram showing another example of the operation of brake control processing performed by the brake control device according to the second embodiment. FIG. 6 is a diagram showing a configuration of a mechanical brake device according to a first embodiment. FIG. 7 is a diagram showing a configuration of a mechanical brake device according to a first embodiment. FIG. 8 is a diagram showing a configuration of a mechanical brake device according to a first embodiment.

[0010] A brake control device, a brake control system, and a brake control method according to embodiments of the present disclosure will be described in detail below with reference to the drawings. In the drawings, the same or equivalent parts are designated by the same reference numerals.

[0011] (Embodiment 1) A brake control device according to embodiment 1 will be described using as an example a brake control device that is mounted on a railway vehicle and controls a mechanical brake device provided for each wheel. In embodiment 1, the railway vehicle is decelerated by the mechanical brake force generated by the mechanical brake device. A brake control system 100 shown in FIG. 1 includes a mechanical brake device 30 that generates a mechanical brake force using the rotational force of a motor 31, and a brake control device 1 that controls the mechanical brake device 30. Note that FIG. 1 shows only the components of the mechanical brake device 30 that are related to electrical control. To avoid complicating the diagram, FIG. 1 shows one mechanical brake device 30, but the brake control device 1 controls multiple mechanical brake devices 30.

[0012] The brake control device 1 includes a target brake force determination unit 11 that determines a target brake force, which is a target value of the brake force, from a brake command obtained from an operation unit 41 provided, for example, in the driver's cab, and a target mechanical brake force determination unit 12 that determines 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.

[0013] The brake control device 1 includes a discrimination unit 13 that determines whether or not the friction material provided in the mechanical brake device 30 is separated from the rotating body that rotates when the railway vehicle is running, and a drive driver 14 that converts the power supplied from the power supply device 42 into power to be supplied to the motor 31 depending on the target mechanical brake force and the discrimination result of the discrimination unit 13, and outputs the converted power to the motor 31.

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

[0015] The mechanical brake device 30 includes a motor 31 driven by power supplied from the brake control device 1 to rotate a drive shaft 31a, a reducer 32 that reduces the rotation speed of the motor 31 and increases the torque for output, and a rotary-to-linear motion conversion mechanism 33 that is connected to the drive shaft 31a via the reducer 32 and slides an output shaft 33a in response to the rotation of the drive shaft 31a. The mechanical brake device 30 also includes a rotation sensor 34 attached near the motor 31 to detect the rotation speed (unit: rpm) of the motor 31, and a load cell 35 attached to one end 33b of the output shaft 33a to measure the pressing force with which the rotary-to-linear motion conversion mechanism 33 presses the friction material 50 against the rotating body 60. To avoid complicating the illustration, only one drive driver 14 is shown in FIG. 1 , but the brake control device 1 includes multiple drive drivers 14 that correspond one-to-one to multiple mechanical brake devices.

[0016] The motor 31 is, for example, a three-phase induction motor driven by three-phase AC power supplied from the brake control device 1. As the output shaft 33a of the rotary-to-linear motion conversion mechanism 33 slides in response to the rotation of the motor 31, the friction material 50 attached to one end 33b of the output shaft 33a moves toward or away from the rotating body 60.

[0017] When the mechanical brake device 30 is not operating, the friction material 50 is separated from the rotating body 60, as shown in Fig. 2. When the mechanical brake device 30 starts operating, specifically when the motor 31 is driven by power supplied from the brake control device 1 and rotates in the forward direction, the rotary-to-linear motion conversion mechanism 33 moves the output shaft 33a toward the rotating body 60 in response to the rotation of the motor 31. As a result, the friction material 50 attached to the end 33b of the output shaft 33a is pressed toward the rotating body 60. As a result, as shown in Fig. 3, the friction material 50 moves to a position where it abuts against the rotating body 60, and is pressed against the rotating body 60 by the rotary-to-linear motion conversion mechanism 33.

[0018] In order to improve the responsiveness of the mechanical brake device 30, it is preferable to quickly move the friction material 50 from the position shown in Fig. 2 to a position where it abuts against the rotating body 60. It is also preferable to suppress an increase in the amount of power consumed by the mechanical brake device 30 while the mechanical brake device 30 is in operation. Details of the brake control device 1 for improving the responsiveness of the mechanical brake device 30 and suppressing an increase in the amount of power consumption will be described below.

[0019] 1 has a master controller that outputs a brake command indicating a deceleration to the target braking force determination unit 11. The master controller outputs a brake command indicating a deceleration corresponding to a notch according to the brake operation by the driver to the target braking force determination unit 11.

[0020] The target braking force determination unit 11 determines a target braking force, which is a target value of the braking force, for each vehicle or bogie from the deceleration indicated by a brake command that instructs the railway vehicle to decelerate. For example, the target braking force determination unit 11 obtains the weight of the vehicle from a load compensation device (not shown) and determines the target braking force for each vehicle by multiplying the vehicle weight 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.

[0021] The target mechanical brake force determination unit 12 determines, from the target brake force, a target mechanical brake force that is a target value for the mechanical brake force generated by each mechanical brake device 30. For example, the target mechanical brake force determination unit 12 determines the target mechanical brake force of the mechanical brake device 30 provided for each wheel from the target brake force for each vehicle. The target mechanical brake force determination unit 12 acquires the pressing force of the mechanical brake device 30 from the load cell 35 of the mechanical brake device 30, and determines an actual mechanical brake force that corresponds to the mechanical brake force that is actually generated. The target mechanical brake force determination unit 12 performs feedback control based on the actual mechanical brake force, adjusts the value of the target mechanical brake force, and sends the adjusted target mechanical brake force to the drive driver 14.

[0022] The discrimination unit 13 determines whether the friction material 50 and the rotating body 60 are separated. In the first embodiment, the discrimination unit 13 determines whether the friction material 50 and the rotating body 60 are separated from each other based on the pressing force of the mechanical brake device 30 obtained from the load cell 35. As an example, when the pressing force of the mechanical brake device 30 can be considered to be 0, it can be considered that the friction material 50 and the rotating body 60 are separated from each other. When the pressing force of the mechanical brake device 30 is greater than 0, it can be considered that the friction material 50 and the rotating body 60 are not separated from each other, in other words, they are in contact with each other. The discrimination unit 13 sends the discrimination result to the drive driver 14.

[0023] The driving driver 14 includes a motor target value determination unit 15 that determines a target torque from the target mechanical braking force and the discrimination result of the discrimination unit 13 and determines a target rotation speed from the target torque; a signal generation unit 16 that generates a PWM (Pulse Width Modulation) signal that instructs a switching operation from the target torque and target rotation speed and outputs the PWM signal; and a power conversion circuit 17 that has a plurality of switching elements that perform switching operation in response to the PWM signal and converts power supplied from a power supply device 42 into power to be supplied to the motor 31 provided in the mechanical braking device 30.

[0024] The motor target value determination unit 15 acquires the target mechanical brake force from the target mechanical brake force determination unit 12, and acquires the rotation speed of the motor 31 from the rotation sensor 34 of the mechanical brake device 30. From the target mechanical brake force, the motor target value determination unit 15 determines a target pushing force, which is a target value of the pushing force of the mechanical brake device 30. From the target pushing force and parameters of the mechanical brake device 30, the motor target value determination unit 15 determines a target torque, which is a target value of the torque of the motor 31.

[0025] The parameters of the mechanical brake device 30 are used to convert the pressing force, which is the force with which the friction material 50 is pressed against the rotating body 60, into the torque of the motor 31. The parameters of the mechanical brake device 30 are determined, for example, by the ratio between the rotational momentum, which is the input to the rotary-to-linear motion conversion mechanism 33, and the linear momentum, which is the output, and the reduction ratio of the reducer 32. It is assumed that the motor target value determination unit 15 stores information about the parameters of the mechanical brake device 30 in advance.

[0026] When the discrimination unit 13 determines that the friction material 50 and the rotating body 60 are separated, the motor target value determination unit 15 sets the target torque to a value smaller than the torque of the motor 31 for pressing the friction material 50 against the rotating body 60. This torque is a torque according to the characteristics of the mechanical brake device 30. For example, when the discrimination unit 13 determines that the friction material 50 and the rotating body 60 are separated, the motor target value determination unit 15 sets the target torque to the minimum torque of the motor 31 for moving the friction material 50 closer to the rotating body 60.

[0027] When the discrimination unit 13 determines that the friction material 50 and the rotating body 60 are not separated, the motor target value determination unit 15 sets the torque of the motor 31 for obtaining the target mechanical braking force as the target torque.

[0028] The motor target value determination unit 15 calculates the target rotation speed from the target torque calculated as described above. Specifically, the motor target value determination unit 15 determines the target rotation speed from the target torque based on the relationship characteristics between the torque and rotation speed of the motor 31. The torque and rotation speed of the motor 31 have a negative correlation. An example of the relationship characteristics between the torque and rotation speed of the motor 31 is shown in FIG. 4 by a line with a negative slope. The position of the line showing the relationship characteristics between the torque and rotation speed of the motor 31 varies depending on the voltage applied to the motor 31. FIG. 4 shows the relationship characteristics corresponding to each of the voltages V1, V2, and V3 applied to the motor 31. Note that V1, V2, and V3 satisfy the equation V1<V2<V3. The motor target value determination unit 15 acquires one of the U-phase voltage command value, V-phase voltage command value, and W-phase voltage command value, and determines the relationship characteristics between the torque and rotation speed of the motor 31 from the acquired voltage command value.

[0029] The motor target value determination unit 15 uses the torque and rotation speed located in the range surrounded by the straight line, the X axis, and the Y axis indicating the relationship characteristic as the target torque and target rotation speed of the motor 31. For example, when the applied voltage of the motor 31 is V2, the motor target value determination unit 15 uses the torque and rotation speed located in the shaded range in FIG. 4 as the target torque and target rotation speed of the motor 31. Specifically, when the applied voltage of the motor 31 is V2, the motor target value determination unit 15 sets the target rotation speed to rotation speed N1, which is the maximum rotation speed possible for target torque τ1, which is the torque for obtaining the target mechanical braking force. When the determination unit 13 determines that the friction material and the rotating body are not separated, the motor target value determination unit 15 outputs the target torque τ1 and target rotation speed N1 calculated as described above to the signal generation unit 16.

[0030] For example, when the discrimination unit 13 determines that the friction material 50 and the rotating body 60 are separated, the motor target value determination unit 15 sets the target torque to a value smaller than the torque of the motor 31 for pressing the friction material 50 against the rotating body 60. For example, the motor target value determination unit 15 sets the minimum torque τ of the motor 31 for moving the friction material 50 closer to the rotating body 60. ＭＩＮ In the example of FIG. 4, the torque τ ＭＩＮ is smaller than the torque τ1 that can press the friction material 50 against the rotating body 60.

[0031] When the applied voltage of the motor 31 is V2, the motor target value determination unit 15 calculates the target torque τ ＭＩＮ The maximum possible rotation speed is N ＭＡＸ When the discriminator 13 determines that the friction material and the rotating body are separated, the motor target value determiner 15 determines the target torque τ ＭＩＮ and target rotation speed N ＭＡＸ is output to the signal generating unit 16.

[0032] Preferably, the motor target value determination unit 15 changes the target torque while maintaining the rate of change of the target torque per unit time within a first target range corresponding to the target value of the rate of change of the deceleration of the railway vehicle. The target value of the rate of change of the deceleration of the railway vehicle is a value that can suppress a deterioration in the ride comfort of the railway vehicle. In other words, the first target range is a range of the rate of change of the torque of the motor 31 that can suppress a deterioration in the ride comfort of the railway vehicle.

[0033] Similarly, it is preferable that the motor target value determiner 15 changes the target rotation speed while maintaining the rate of change of the target rotation speed per unit time within a second target range corresponding to the target value of the rate of change of the deceleration of the railway vehicle. In other words, the second target range is a range of the rate of change of the rotation speed of the motor 31 that can suppress deterioration of the riding comfort of the railway vehicle.

[0034] The signal generating unit 16 generates and outputs a plurality of PWM signals for controlling a plurality of switching elements of the power conversion circuit 17 from the target torque obtained from the motor target value determining unit 15, the actual torque which is the torque of the actual motor 31, the target rotation speed obtained from the motor target value determining unit 15, and the actual rotation speed which is the rotation speed of the actual motor 31.

[0035] Specifically, the signal generator 16 obtains the target torque of the motor 31 from the motor target value determiner 15 and obtains a measured value of the output current of the power conversion circuit 17 from the current sensor 18. Specifically, the signal generator 16 obtains the measured values ​​of the U-phase current and the V-phase current from the current sensor 18 and determines the value of the W-phase current from the measured values ​​of the U-phase current and the V-phase current. The signal generator 16 determines the actual torque of the motor 31 from the U-phase current, the V-phase current, and the W-phase current. The signal generator 16 performs feedback control based on the target torque and the actual torque to determine a U-phase voltage command value, a V-phase voltage command value, and a W-phase voltage command value. The signal generator 16 generates a PWM signal by comparing the U-phase voltage command value, the V-phase voltage command value, and the W-phase voltage command value with the value of a triangular wave signal having a frequency corresponding to the target rotation speed. It is preferable that the signal generator 16 perform feedback control based on the target rotation speed and the actual rotation speed. The signal generating unit 16 outputs a PWM signal to each switching element included in the power conversion circuit 17 .

[0036] The power conversion circuit 17 has a plurality of switching elements controlled by a PWM signal supplied from the signal generation unit 16. Through the switching operations of the plurality of switching elements, the power conversion circuit 17 converts the DC power supplied from the power supply device 42 into three-phase AC power, and supplies the three-phase AC power to the motor 31 of the mechanical brake device 30.

[0037] The power supply device 42 converts power supplied from a current collector (not shown) into power to be supplied to the power conversion circuit 17, and outputs the converted power to the power conversion circuit 17. The power supply device 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 the DC power into AC power, and a rectifier circuit that rectifies the AC power into DC power.

[0038] The hardware configuration of the brake control device 1 having the above-described configuration is shown in Figure 5. The brake control device 1 includes a processor 81, a memory 82, and an interface 83. The processor 81, the memory 82, and the interface 83 are connected to one another via a bus 80. The functions of each unit 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 processor 81 reads and executes the programs stored in the memory 82, thereby realizing the functions of each unit described above. In other words, the memory 82 stores programs for executing the processing of each unit of the brake control device 1.

[0039] The memory 82 includes, for example, non-volatile or volatile semiconductor memory 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 disk, flexible disk, optical disk, compact disk, mini disk, DVD (Digital Versatile Disc), etc.

[0040] The brake control device 1 is connected to the operating unit 41, the power supply device 42, and the mechanical brake device 30 via an interface 83. The interface 83 has an interface module that complies with one or more standards depending on the connected device.

[0041] The brake control process performed by the brake control device 1 having the above configuration will be described with reference to Fig. 6. When the railway vehicle starts operation, the brake control device 1 starts the process shown in Fig. 6. Specifically, when a lift switch is operated to bring a pantograph, which is an example of a current collector, into contact with an overhead wire, which is an example of a power supply line, the brake control device 1 starts the process shown in Fig. 6.

[0042] The target braking force determination unit 11 repeats the process of step S11 while it has not acquired a braking command from the operation unit 41 (step S11; No).

[0043] When the target braking force determination unit 11 receives a braking command from the operation unit 41 (step S11; Yes), the target braking force determination unit 11 calculates a target braking force from the deceleration indicated by the braking command (step S12). The target braking force determination unit 11 sends the calculated target braking force to the target mechanical braking force determination unit 12.

[0044] The target mechanical brake force determination unit 12 determines the target mechanical brake force of each mechanical brake device 30 from the target brake force determined in step S12 (step S13).

[0045] The determination unit 13 determines whether or not the friction material 50 and the rotating body 60 are separated from each other based on the measurement value of the load cell 35 (step S14).

[0046] When it is determined that the friction material 50 and the rotating body 60 are separated (step S14; Yes), the motor target value determination unit 15 included in the driver 14 sets the target torque to a value smaller than the torque of the motor 31 for pressing the friction material 50 against the rotating body 60 (step S15). In detail, the motor target value determination unit 15 sets the target torque to the minimum torque of the motor 31 for moving the friction material 50 closer to the rotating body 60, in other words, the minimum torque of the motor 31 that can move the friction material 50 toward the rotating body 60.

[0047] When it is determined that the friction material 50 and the rotating body 60 are not separated, in other words, that the friction material 50 and the rotating body 60 are in contact (step S14; No), the motor target value determination unit 15 of the drive driver 14 calculates the torque of the motor 31 to obtain the target mechanical braking force from the target pressing force corresponding to the target mechanical braking force calculated in step S13, and sets the torque of the motor 31 to obtain the target mechanical braking force as the target torque (step S16).

[0048] The motor target value determination unit 15 determines the target rotation speed from the target torque determined in step S15 or S16 based on the relationship between the torque and rotation speed of the motor 31 (step S17).

[0049] The signal generating unit 16 of the driving driver 14 generates a PWM signal according to the target torque calculated in step S15 or S16 and the target rotation speed calculated in step S17, and sends the PWM signal to each switching element of the power conversion circuit 17, thereby causing the power conversion circuit 17 to supply power to the motor 31 and controlling the mechanical brake device 30 (step S18). Specifically, the power conversion circuit 17 converts the power supplied from the power supply device 42 into power to be supplied to the motor 31 in accordance with the PWM signal, and supplies the converted power to the motor 31.

[0050] When the motor 31 receives the supply of electric power and rotates in the forward direction, the friction material 50 attached to the end 33b of the output shaft 33a of the rotary-to-linear motion conversion mechanism 33 is pressed toward the rotating body 60. As a result, the friction material 50 is pressed against the rotating body 60, generating a braking force.

[0051] When the process of step S18 is completed, the brake control device 1 repeats the above-described process from step S11. The brake control device 1 repeats the brake control process shown in Fig. 6 at predetermined intervals while the railway vehicle is in operation.

[0052] 7 is a timing chart showing an example of the operation of the brake control process by the brake control device 1. The timing when a brake command is input is defined as time T1. After time T1, the timing when the friction material 50 comes into contact with the rotating body 60 and a mechanical braking force begins to act is defined as time T2.

[0053] As shown in graph A, no brake command is input until time T1. Therefore, as shown in graph B, the target mechanical brake force is not determined in the target mechanical brake force determination unit 12 until time T1. Similarly, as shown in graphs C and D, the target torque and target rotation speed are not determined in the motor target value determination unit 15 until time T1. As a result, as shown in graph E, the friction material 50 is not pressed against the rotating body 60, and therefore no mechanical brake force is generated in the mechanical brake device 30.

[0054] As shown in graph A, when a brake command indicating brake notch BN1 is supplied to the brake control device 1 at time T1, the target brake force determination unit 11 calculates a target brake force from the brake notch BN1. As shown in graph C, the target mechanical brake force determination unit 12 calculates a target mechanical brake force for each mechanical brake device 30 from the target brake force corresponding to the brake notch BN1. The value of the target mechanical brake force at this time is set to BP1.

[0055] The motor target value determination unit 15 of the driver 14 determines the target torque and target rotation speed of the motor 31. Between time T1 and time T2, the friction material 50 and the rotating body 60 are separated from each other. Therefore, as shown in graph C, the motor target value determination unit 15 determines the minimum torque τ of the motor 31 that can bring the friction material 50 closer to the rotating body 60. ＭＩＮ is the target torque.

[0056] As shown in graph D, the motor target value determination unit 15 determines the maximum rotation speed N according to the target torque. ＭＡＸ is the target rotation speed.

[0057] The signal generating unit 16 sends a PWM signal corresponding to the target torque and the target rotation speed to each switching element of the power conversion circuit 17, and the power converted by the power conversion circuit 17 is supplied to the motor 31. ＭＩＮ By setting the target rotation speed to 0.5 V, the target rotation speed becomes sufficiently high, and the friction material 50 quickly comes into contact with the rotating body 60. As a result, the friction material 50 comes into contact with the rotating body 60 at time T2.

[0058] After time T2, the friction material 50 and the rotating body 60 are in contact with each other. Therefore, the motor target value determination unit 15 sets the target torque to τ1, which is the torque required to obtain the target mechanical braking force BP1. Furthermore, as shown in graph D, the motor target value determination unit 15 sets the target rotational speed to N1, which corresponds to the target torque τ1.

[0059] As shown in graph C, the motor target value determiner 15 changes the target torque while maintaining the rate of change of the target torque per unit time within a first target range corresponding to the target value of the rate of change of the deceleration of the railway vehicle. As a result, the value of the target torque output by the motor target value determiner 15 to the signal generator 16 at time T3 reaches τ1.

[0060] Similarly, as shown in graph D, the motor target value determination unit 15 changes the target rotation speed while maintaining the rate of change per unit time of the target rotation speed within a second target range corresponding to the target value of the rate of change of the deceleration of the railway vehicle. As a result, the value of the target rotation speed output by the motor target value determination unit 15 to the signal generation unit 16 reaches N1 at time T3. When the friction material 50 and the rotating body 60 come into contact with each other, the rotation speed is reduced, thereby reducing the power consumption of the motor 31. As a result, the amount of power consumed by the mechanical brake device 30 is reduced.

[0061] After time T2, as shown in graph E, the friction material 50 is pressed against the rotating body 60, causing a braking force to be generated by the mechanical brake device 30, and the railway vehicle decelerates as shown in graph F. Thereafter, at time T4, the railway vehicle stops.

[0062] As described above, the brake control device 1 according to the first embodiment sets the target torque to a value smaller than the torque of the motor 31 for generating a mechanical braking force by pressing the friction material 50 against the rotating body 60 when the friction material 50 and the rotating body 60 are separated. By reducing the target torque when the friction material 50 and the rotating body 60 are separated, the target rotation speed can be increased, making it possible to quickly bring the friction material 50 closer to the rotating body 60. Thereafter, when the friction material 50 and the rotating body 60 come into contact with each other, the torque of the motor 31 for obtaining the target mechanical braking force is set as the target torque, thereby decreasing the target rotation speed and making it possible to reduce the amount of power consumed by the motor 31. In other words, the brake control device 1 makes it possible to reduce the amount of power consumed while maintaining the responsiveness of the mechanical brake device 30.

[0063] (Embodiment 2) The method of determining whether or not the friction material 50 and the rotating body 60 are separated is not limited to the above example, and is arbitrary. A brake control device that determines whether or not the friction material 50 and the rotating body 60 are separated using a method different from that of Embodiment 1 will be described in Embodiment 2, focusing on the differences from Embodiment 1. The brake control device according to Embodiment 2 will be described using as an example a brake control device that is mounted on a railway vehicle that decelerates using at least one of a mechanical brake force and an electric brake force, and controls a mechanical brake device 30 provided for each wheel.

[0064] The brake control system 101 shown in Fig. 8 includes a mechanical brake device 30 and a brake control device 2 that controls the mechanical brake device 30. Note that Fig. 8 shows only the components related to electrical control among the components of the mechanical brake device 30.

[0065] The target brake force determination unit 11 determines, from the determined target brake force, a target electric brake force that is a target value for the electric brake force generated by consuming the electric power generated when the traction motor that generates the propulsion force for the railway vehicle operates as a generator. The target brake force determination unit 11 sends the determined target electric brake force to the main circuit control device 43.

[0066] The main circuit control device 43 converts power supplied from the current collector into power to be supplied to the traction motors and supplies the converted power to the traction motors, or controls a main power conversion device that converts power supplied from the traction motors operating as generators into power to be supplied to other railway vehicles and outputs the converted power to the current collectors. During braking, the main circuit control device 43 controls the main power conversion device in accordance with the target electric brake force obtained from the target brake force determination unit 11. Electric brake force is generated when power supplied from the traction motors operating as generators is supplied to and consumed by other railway vehicles. The main circuit control device 43 sends regenerative feedback indicating the actual electric brake force, which is the electric brake force that is actually generated, to the target mechanical brake force determination unit 12.

[0067] The target mechanical brake force determination unit 12 calculates the target mechanical brake force, which is a target value of the mechanical brake force generated by the mechanical brake device 30 provided for each wheel, from the difference between the target brake force and the actual electric brake force indicated by the regenerative feedback. As in the first embodiment, the target mechanical brake force determination unit 12 performs feedback control based on the actual mechanical brake force to adjust the value of the target mechanical brake force and sends the adjusted target mechanical brake force to the drive driver 14.

[0068] The determination unit 13 determines whether the friction material 50 and the rotating body 60 are separated from each other based on the cumulative value of the number of rotations of the motor 31 since the mechanical brake device 30 started operating and the distance between the friction material 50 and the rotating body 60 when the mechanical brake device 30 is stopped. Specifically, the determination unit 13 accumulates the number of rotations each time the number of rotations of the motor 31 is obtained from the rotation sensor 34 after the mechanical brake device 30 started operating. The cumulative value of the number of rotations indicates the total number of rotations of the motor 31 from the start of operation of the mechanical brake device 30 to the calculation timing of the cumulative value. The determination unit 13 considers the time when the motor 31 starts rotating from a stopped state as the time when the mechanical brake device 30 started operating. In other words, the determination unit 13 considers the mechanical brake device 30 to have started operating when the number of rotations obtained from the rotation sensor 34 exceeds 0.

[0069] The determination unit 13 determines whether the friction material 50 and the rotating body 60 are separated from each other based on the integrated value of the rotational speed calculated as described above and a reference rotational speed determined according to the distance between the friction material 50 and the rotating body 60 when the mechanical brake device 30 is stopped. The reference rotational speed is determined from the distance between the friction material 50 and the rotating body 60 when the mechanical brake device 30 is stopped, based on parameters of the mechanical brake device 30, specifically, the ratio between the rotational momentum that is the input to the linear momentum that is the output of the rotary-to-linear motion conversion mechanism 33 and the reduction ratio of the reducer 32. If the integrated value of the rotational speed is less than the reference rotational speed, the friction material 50 and the rotating body 60 can be considered to be separated from each other. If the integrated value of the rotational speed is equal to or greater than the reference rotational speed, the friction material 50 and the rotating body 60 can be considered to be in contact with each other. The determination unit 13 is assumed to store information about the reference rotational speed in advance.

[0070] The hardware configuration of the brake control device 2 is similar to the hardware configuration of the brake control device 1 according to the first embodiment.

[0071] The brake control processing performed by the brake control device 2 will be described with reference to Figure 9. The brake control device 2 starts the processing shown in Figure 9 when the railway vehicle starts operation. The processing of steps S11-S18 in Figure 9 is the same as the processing of steps S11-S18 performed by the brake control device 1 according to embodiment 1 shown in Figure 6. After determining the target brake force in step S12, the target brake force determination unit 11 determines the electric brake force from the target brake force (step S21). In step S13, the target mechanical brake force determination unit 12 determines the target mechanical brake force from the difference between the target brake force and the actual electric brake force indicated by the regenerative feedback.

[0072] In step S14, the determination unit 13 determines whether the friction material 50 and the rotating body 60 are separated from each other based on whether the integrated value of the rotation speed is equal to or greater than the reference rotation speed.

[0073] When the actual electric brake force is equal to or greater than the target brake force, the target mechanical brake force calculated in step S13 is 0, so in step S16, the motor target value determination unit 15 sets the target torque to 0. When the actual electric brake force is less than the target brake force, the target mechanical brake force calculated in step S13 is a value greater than 0, so in step S16, the motor target value determination unit 15 sets the torque of the motor 31 for obtaining the target mechanical brake force as the target torque.

[0074] If the target torque is set to 0 in step S16, the motor target value determination unit 15 sets the target rotation speed to 0 in step S17.

[0075] 10 is a timing chart showing an example of the operation of the brake control process by the brake control device 2. The timing when a brake command is input is defined as time T11. After time T11, the timing when the friction material 50 comes into contact with the rotating body 60 is defined as time T12.

[0076] As shown in graph A, no brake command is input until time T11. Therefore, as shown in graph B, the target mechanical brake force is not determined in the target mechanical brake force determination unit 12 until time T11. Similarly, as shown in graphs C and D, the target torque and target rotation speed are not determined in the motor target value determination unit 15 until time T11. As a result, as shown in graph G, the friction material 50 is not pressed against the rotating body 60, and therefore no mechanical brake force is generated in the mechanical brake device 30.

[0077] As shown in graph A, when a brake command indicating brake notch BN1 is supplied to the brake control device 1 at time T11, the target brake force determination unit 11 obtains the target brake force from the brake notch BN1.

[0078] The target brake force determination unit 11 determines the target electric brake force from the target brake force, as shown in graph B. It is assumed that the target electric brake force EBP1 coincides with the target brake force. The main circuit control device 43 controls the main power conversion device in accordance with the target electric brake force, thereby generating an electric brake force EBP1', as shown in graph C. It is assumed that the electric brake force EBP1' coincides with the target electric brake force EBP1.

[0079] The target mechanical brake force determination unit 12 calculates the target mechanical brake force for each mechanical brake device 30 from the difference between the target brake force corresponding to the brake notch BN1 and the actual electric brake force indicated by the regenerative feedback, as shown in graph D. As shown in graph D, from time T11 onwards, the target mechanical brake force is 0 while an electric brake force EBP1' that can be considered to match the target electric brake force EBP1 is being generated.

[0080] The motor target value determination unit 15 of the driver 14 determines the target torque and target rotation speed of the motor 31. Between time T11 and time T12, the friction material 50 and the rotating body 60 are separated from each other. Therefore, the motor target value determination unit 15 determines the minimum torque τ of the motor 31 that can move the friction material 50 closer to the rotating body 60, as shown in graph E. ＭＩＮ is the target torque.

[0081] As shown in graph F, the motor target value determination unit 15 determines the minimum torque τ ＭＩＮ Maximum rotation speed N according to ＭＡＸ is the target rotation speed.

[0082] The signal generating unit 16 sends a PWM signal corresponding to the target torque and the target rotation speed to each switching element of the power conversion circuit 17, and the power converted by the power conversion circuit 17 is supplied to the motor 31. ＭＩＮ By setting the target rotation speed to 0.5 V, the target rotation speed becomes sufficiently high, and the friction material 50 quickly comes into contact with the rotating body 60. As a result, the friction material 50 comes into contact with the rotating body 60 at time T12.

[0083] At time T12, the target mechanical braking force is 0. After time T12, the discrimination unit 13 determines that the friction material 50 and the rotating body 60 are not separated. As a result, at time T12, the motor target value determination unit 15 sets the target torque and the target rotation speed to 0, as shown in graphs E and F.

[0084] At time T12, the friction material 50 is in contact with the rotating body 60, but the target torque and the target rotation speed are set to 0. Therefore, as shown in graph G, the friction material 50 is not pressed against the rotating body 60, and therefore no mechanical braking force is generated in the mechanical brake device 30.

[0085] After time T12, the timing at which electric brake force cannot be obtained due to, for example, regeneration expiration, is designated as time T13. At time T13, the actual brake force indicated by the regeneration feedback becomes zero, and as shown in graph D, the target mechanical brake force determined by the target mechanical brake force determination unit 12 increases.

[0086] Since the discrimination unit 13 determines that the friction material 50 and the rotating body 60 are not separated, the motor target value determination unit 15 sets the target torque to torque τ1 for obtaining the target mechanical braking force, as shown in graph E.

[0087] As shown in graph F, the motor target value determination unit 15 sets the maximum rotation speed N1 corresponding to the target torque τ1 as the target rotation speed.

[0088] As shown in graph E, the motor target value determiner 15 changes the target torque while maintaining the rate of change of the target torque per unit time within a first target range corresponding to the target value of the rate of change of the deceleration of the railway vehicle. As a result, the value of the target torque output by the motor target value determiner 15 to the signal generator 16 at time T14 reaches τ1.

[0089] Similarly, as shown in graph F, the motor target value determination unit 15 changes the target rotation speed while maintaining the rate of change per unit time of the target rotation speed within a second target range corresponding to the target value of the rate of change of the deceleration of the railway vehicle. As a result, the value of the target rotation speed output by the motor target value determination unit 15 to the signal generation unit 16 reaches N1 at time T14. When the friction material 50 and the rotating body 60 come into contact with each other, the rotation speed is reduced, thereby reducing the power consumption of the motor 31. As a result, the amount of power consumed by the mechanical brake device 30 is reduced.

[0090] After time T13, as shown in graph G, the friction material 50 is pressed against the rotating body 60, causing a braking force to be generated by the mechanical brake device 30, and the railway vehicle decelerates as shown in graph H. Thereafter, at time T15, the railway vehicle stops.

[0091] 11 is a timing chart showing another example of the operation of the brake control process by the brake control device 2. As in FIG. 10 , the timing when a brake command is input is defined as time T11. After time T11, the timing when the friction material 50 comes into contact with the rotating body 60 is defined as time T12.

[0092] As shown in graph A, no brake command is input until time T11. Therefore, as shown in graph B, the target mechanical brake force is not determined in the target mechanical brake force determination unit 12 until time T11. Similarly, as shown in graphs C and D, the target torque and target rotation speed are not determined in the motor target value determination unit 15 until time T11. As a result, as shown in graph G, the friction material 50 is not pressed against the rotating body 60, and therefore no mechanical brake force is generated in the mechanical brake device 30.

[0093] As shown in graph A, when a brake command indicating brake notch BN1 is supplied to the brake control device 2 at time T11, the target brake force determination unit 11 obtains the target brake force from the brake notch BN1.

[0094] The target brake force determination unit 11 calculates the target electric brake force from the target brake force, as shown in graph B. The target electric brake force EBP1 is assumed to coincide with the target brake force. The main circuit control device 43 controls the main power conversion device in accordance with the target electric brake force, but when there are no powered railway cars nearby, regeneration is disabled and no actual electric brake force is generated, as shown in graph C.

[0095] The target mechanical brake force determination unit 12 determines the target mechanical brake force for each mechanical brake device 30 from the difference between the target brake force corresponding to the brake notch BN1 and the actual electric brake force indicated by the regenerative feedback, as shown in graph D. When an electric brake force corresponding to the target electric brake force is not generated at time T11, the target mechanical brake force determination unit 12 determines the target mechanical brake force for each mechanical brake device 30 from the target brake force, as shown in graph D. The value of the target mechanical brake force at this time is set to BP1.

[0096] The motor target value determination unit 15 of the driver 14 determines the target torque and target rotation speed of the motor 31. Between time T11 and time T12, the friction material 50 and the rotating body 60 are separated from each other. Therefore, the motor target value determination unit 15 determines the minimum torque τ of the motor 31 that can move the friction material 50 closer to the rotating body 60, as shown in graph E. ＭＩＮ is the target torque.

[0097] As shown in graph F, the motor target value determination unit 15 determines the minimum torque τ ＭＩＮ Maximum rotation speed N according to ＭＡＸ is the target rotation speed.

[0098] The signal generating unit 16 sends a PWM signal corresponding to the target torque and the target rotation speed to each switching element of the power conversion circuit 17, and the power converted by the power conversion circuit 17 is supplied to the motor 31.ＭＩＮ By setting the target rotation speed to 0.5 V, the target rotation speed becomes sufficiently high, and the friction material 50 quickly comes into contact with the rotating body 60. As a result, the friction material 50 comes into contact with the rotating body 60 at time T12.

[0099] At time T12, the target mechanical braking force is BP1. After time T12, the discrimination unit 13 determines that the friction material 50 and the rotating body 60 are not separated. As a result, at time T12, the motor target value determination unit 15 determines the target torque for obtaining the target mechanical braking force BP1 and the target rotation speed corresponding to the target torque, as shown in graphs E and F.

[0100] By supplying the motor 31 with electric power according to the target torque and target rotation speed calculated as described above, the motor 31 is driven to rotate, and as shown in graph G, the pressing force, which is the force with which the friction material 50 is pressed against the rotating body 60 by the rotational force of the motor 31, increases. As a result, as shown in graph H, the railway vehicle decelerates.

[0101] After time T12, the timing at which the electric braking force is generated is set to time T21. As shown in graph C, the generation of the actual electric braking force causes the target mechanical braking force determination unit 12 to reduce the target mechanical braking force as shown in graph D. As the target mechanical braking force decreases, the motor target value determination unit 15 reduces the target torque and target rotation speed as shown in graphs E and F. Thereafter, the target torque and target rotation speed reach zero. As a result, as shown in graph G, the pressing force, which is the force pressing the friction material 50 against the rotating body 60, decreases. Note that because the electric braking force is being generated, the railway vehicle continues to decelerate as shown in graph H.

[0102] After time T21, the timing at which the electric brake force begins to decrease due to, for example, regeneration expiration is set to time T22. When regeneration expiration occurs at time T22, the actual electric brake force decreases, as shown in graph C. As a result, the target mechanical brake force determination unit 12 increases the target mechanical brake force, as shown in graph D. At time T23, the target mechanical brake force reaches BP1. As the target mechanical brake force increases, the motor target value determination unit 15 increases the target torque from 0 and sets a target rotational speed greater than 0 in accordance with the target torque. Thereafter, at time T24, the target torque reaches τ1, and the target rotational speed reaches rotational speed N1 corresponding to torque τ1.

[0103] After time T22, as shown in graph G, the friction material 50 is pressed against the rotating body 60, and the braking force by the mechanical brake device 30 increases. As shown in graph H, even though the electric brake force decreases, the railway vehicle continues to decelerate due to the increase in the mechanical brake force by the mechanical brake device 30. Thereafter, at time T25, the railway vehicle stops.

[0104] As described above, the brake control device 2 according to the second embodiment sets the target torque to a value smaller than the torque of the motor 31 for generating a mechanical braking force by pressing the friction material 50 against the rotating body 60 when the friction material 50 and the rotating body 60 are separated. By reducing the target torque when the friction material 50 and the rotating body 60 are separated, the target rotation speed can be increased, making it possible to quickly bring the friction material 50 closer to the rotating body 60. Thereafter, when the friction material 50 and the rotating body 60 come into contact with each other, the torque of the motor 31 for obtaining the target mechanical braking force is set as the target torque, thereby decreasing the target rotation speed and making it possible to reduce the amount of power consumed by the motor 31. In other words, the brake control device 1 makes it possible to reduce the amount of power consumed while maintaining the responsiveness of the mechanical brake device 30.

[0105] When the electric braking force is being generated, the motor 31 is controlled based on the increased target rotation speed to bring the friction material 50 closer to the rotating body 60, thereby enabling the mechanical braking device 30 to operate quickly when the electric braking force begins to decrease due to, for example, regeneration failure. In other words, the responsiveness of the mechanical braking device 30 is improved.

[0106] (Embodiment 3) The configuration of the mechanical brake device is not limited to the above-described example, and may be any configuration that generates a mechanical brake force by pressing the friction material 50 against the rotating body 60 with the rotational force of a motor. Furthermore, the method of determining whether the friction material 50 and the rotating body 60 are separated is not limited to the above-described example, and may be any configuration. A brake control device that determines whether the friction material 50 and the rotating body 60 are separated using a method different from those of Embodiments 1 and 2, and controls a mechanical brake device having a different configuration from Embodiments 1 and 2, will be described in Embodiment 3, focusing on the differences from Embodiments 1 and 2.

[0107] The brake control system 102 shown in Fig. 12 includes a mechanical brake device 40 that generates a mechanical brake force based on the rotational force of a motor 31, and a brake control device 3 that controls the mechanical brake device 40. Note that Fig. 12 shows only the components related to electrical control among the components of the mechanical brake device 40.

[0108] As shown in Fig. 13, the mechanical brake device 40 includes, in addition to the configuration of the mechanical brake device 30, a holding mechanism 36 that holds and limits the sliding of the output shaft 33a. The holding mechanism 36 has, for example, a solenoid. The holding mechanism 36 attracts the output shaft 33a, which is made of a magnetic material, by magnetic force generated when the solenoid is energized, thereby limiting the sliding of the output shaft 33a and holding the output shaft 33a with the sliding limited. When the solenoid is not energized, the holding mechanism 36 allows the output shaft 33a to slide.

[0109] 12 , in addition to the configuration of the brake control device 1, the brake control device 3 includes a holding mechanism control unit 19 that switches on and off a relay 45 that electrically connects the solenoid of the holding mechanism 36 to the solenoid power supply 44. The holding mechanism control unit 19 switches on and off the relay 45 in response to an instruction from the motor target value determination unit 15.

[0110] The determination unit 13 determines whether the friction material 50 is separated from the rotating body 60 based on the current flowing from the driver 14 to the motor 31. Specifically, the determination unit 13 determines whether the rate of increase in the amplitude of the measurement value of the current sensor 18 is within a target range. When the friction material 50 comes into contact with the rotating body 60, the rotation of the motor 31 is restricted, and the actual rotation speed of the motor 31 decreases. As a result, the difference between the target rotation speed and the actual rotation speed increases, and the current flowing from the driver 14 to the motor 31 rapidly increases due to feedback control by the driver 14.

[0111] Therefore, the determination unit 13 determines whether the friction material 50 is separated from the rotating body 60 by comparing the rate of increase in the amplitude of the current flowing from the driver 14 to the motor 31 with a target range. If the rate of increase in the amplitude of the measurement value of the current sensor 18 is within the target range, it can be assumed that the friction material 50 is separated from the rotating body 60. If the rate of increase in the amplitude of the measurement value of the current sensor 18 exceeds the target range, it can be assumed that the friction material 50 is not separated from the rotating body 60. The target range may be any range wider than the range in which the amplitude of the current can vary when the friction material 50 is separated from the rotating body 60.

[0112] The motor target value determination unit 15 sends an ON command to the relay 45 when the target torque is constant and the determination unit 13 determines that the friction material 50 and the rotating body 60 are not separated, and this state continues for a reference time or more determined in accordance with the characteristics of the motor 31. If the brake command changes while the ON command is being sent to the relay 45, the motor target value determination unit 15 sends an OFF command to the relay 45. A constant target torque means that the rate of change of the target torque per unit time is sufficiently small. The length of the reference time may be determined in accordance with the length of time during which high torque and low speed driving are allowed, in accordance with the characteristics of the motor 31.

[0113] When the relay 45 is in the OFF state, the solenoid of the holding mechanism 36 is electrically disconnected from the solenoid power supply 44. Therefore, no magnetic force is generated in the solenoid, and as a result, the output shaft 33a is able to slide.

[0114] When the relay 45 is turned on, the solenoid of the holding mechanism 36 is electrically connected to the solenoid power supply 44. When the solenoid is energized, a magnetic force is generated, suppressing sliding of the output shaft 33a. The holding mechanism 36 having the solenoid holds the output shaft 33a, with sliding suppressed. When the relay 45 is turned on while the friction material 50 is pressed against the rotating body 60, the holding mechanism 36 having the solenoid suppresses sliding of the output shaft 33a and holds it. As a result, the state in which the friction material 50 is pressed against the rotating body 60 is maintained. In other words, it is possible to continue generating a mechanical braking force even if the motor 31 is not driven.

[0115] The hardware configuration of the brake control device 3 is similar to the hardware configuration of the brake control device 1 according to the first embodiment.

[0116] The brake control process performed by the brake control device 3 having the above configuration will be described with reference to Fig. 14. When the railway vehicle starts operation, the brake control device 3 starts the process shown in Fig. 14. The process of steps S11 to S18 in Fig. 14 is the same as the process of steps S11 to S18 performed by the brake control device 1 according to the first embodiment shown in Fig. 6.

[0117] If the discriminator 13 determines that the friction material 50 and the rotating body 60 are not separated (step S14; No), the target torque is constant, and the state in which the discriminator 13 determines that the friction material 50 and the rotating body 60 are not separated continues for a reference time or longer determined according to the characteristics of the motor 31 (step S31; Yes), the brake control device 3 controls the holding mechanism 36 to limit and hold the output shaft 33a (step S32). Specifically, in step S32, the motor target value determiner 15 sends an instruction to the holding mechanism control unit 19 to turn on the relay 45, and the holding mechanism control unit 19 turns on the relay 45. As a result, the solenoid of the holding mechanism 36 is electrically connected to the solenoid power supply 44, generating a magnetic force in the solenoid and attracting the output shaft 33a, which is made of a magnetic material, to the solenoid. As a result, the sliding of the output shaft 33a is suppressed, and the output shaft 33a is held by the holding mechanism 36.

[0118] When the target torque is constant and the state in which the discrimination unit 13 determines that the friction material 50 and the rotating body 60 are not separated does not continue for more than a reference time determined in accordance with the characteristics of the motor 31 (step S31; No), the processing of step S16 is performed as in embodiment 1.

[0119] An example of the target torque and the target rotation speed in the brake control by the brake control device 3 is shown in Figure 15. The operation of each part of the brake control device 3 at times T1, T2, T3, and T4 is the same as the operation of each part of the brake control device 1 shown in Figure 7. As shown in graph E, the relay 45 is off at the start.

[0120] As shown in graph C, the target torque is constant after time T3. As shown in graph F, the friction material 50 and the rotating body 60 are in contact with each other after time T2.

[0121] The timing at which a reference time has elapsed since time T3 is defined as time T31. If, at time T31, motor target value determination unit 15 determines that the target torque can be considered constant and that the state in which friction material 50 and rotating body 60 are not separated has continued for at least the reference time, it sends an instruction to hold mechanism control unit 19 to turn on relay 45. After sending an instruction to hold mechanism control unit 19 to turn on relay 45, motor target value determination unit 15 sets the target torque and target rotation speed to zero, as shown in graphs C and D.

[0122] In accordance with an instruction from the motor target value determination unit 15, the holding mechanism control unit 19 turns on the relay 45 at time T31, as shown in graph E. As a result, the solenoid of the holding mechanism 36 is electrically connected to the solenoid power supply 44, and a magnetic force of the solenoid is generated. The magnetic force of the solenoid attracts the output shaft 33a, suppressing sliding of the output shaft 33a. With the friction material 50 pressed against the rotating body 60, the holding mechanism 36 holds the output shaft 33a, whose sliding is suppressed, thereby maintaining the pressing force, as shown in graph F. As a result, as shown in graph G, the railway vehicle continues to decelerate and stops at time T4.

[0123] As described above, when the target torque is constant and the state in which the friction material 50 and the rotating body 60 are not separated continues for a reference time or longer, the brake control device 3 according to the third embodiment controls the holding mechanism 36 to suppress sliding of the output shaft 33a and hold the output shaft 33a. With the friction material 50 pressed against the rotating body 60, the holding mechanism 36 holds the output shaft 33a in which sliding is suppressed, thereby maintaining the pressing force. By preventing the motor 31 from operating at a high torque and low speed for a long period of time, the generation of an overcurrent in the motor 31 is suppressed.

[0124] The present disclosure is not limited to the above-described embodiments. The above-described embodiments can be combined as desired. As an example, the brake control device 2 may further include a holding mechanism control unit 19 included in the brake control device 3, and control the mechanical brake device 40. As another example, the brake control device 1 may determine whether the friction material 50 and the rotating body 60 are separated from each other based on the current flowing from the drive driver 14 to the motor 31, like the determination unit 13 included in the brake control device 3. As another example, the target mechanical brake force determination unit 12 included in the brake control devices 1 and 3 may calculate the target mechanical brake force from the difference between the target brake force and the actual electric brake force, similar to the brake control device 2.

[0125] The determination method of the determination unit 13 may be any method capable of determining whether the friction material 50 and the rotating body 60 are separated from each other. As an example, the determination unit 13 may determine whether the friction material 50 and the rotating body 60 are separated from each other based on the integrated value of the rotational speed of the motor 31 and a reference rotational speed corresponding to a distance shorter than the distance between the friction material 50 and the rotating body 60 when the mechanical brake device 30 is stopped. The reference rotational speed in this case is a distance sufficiently close to the distance between the friction material 50 and the rotating body 60 when the mechanical brake device 30 is stopped, for example, a reference rotational speed corresponding to a distance when the distance between the friction material 50 and the rotating body 60 when the mechanical brake device 30 is stopped is 5 mm or less. This makes it possible to move the friction material 50 to a position sufficiently close to the rotating body 60 without contacting the rotating body 60 while a brake command is input and the electric brake force is operating. This makes it possible to quickly operate the mechanical brake device 30 when the electric brake force decreases.

[0126] The method for setting the target rotation speed by the motor target value determination unit 15 is not limited to the above example. As an example, the motor target value determination unit 15 may gradually decrease the target rotation speed from the maximum rotation speed corresponding to the minimum torque when the distance between the friction material 50 and the rotating body 60 becomes sufficiently small. Specifically, the motor target value determination unit 15 may gradually decrease the target rotation speed after a certain period of time has elapsed during which the motor 31 is controlled using the maximum rotation speed corresponding to the minimum torque as the target rotation speed. This certain period of time is determined by the rotation speed of the motor 31, the distance between the friction material 50 and the rotating body 60 when the mechanical brake device 30 is stopped, the ratio between the rotational momentum that is the input to the linear momentum that is the output of the rotary-to-linear motion conversion mechanism 33, the reduction ratio of the reducer 32, etc.

[0127] Alternatively, the motor target value determination unit 15 may gradually decrease the target rotation speed when the integrated value of the rotation speed of the motor 31 during the period in which the motor 31 is controlled with the maximum rotation speed corresponding to the minimum torque as the target rotation speed reaches or exceeds a threshold value. This threshold value is determined by the distance between the friction material 50 and the rotating body 60 when the mechanical brake device 30 is stopped, the ratio between the rotational momentum that is the input to the linear momentum that is the output of the rotary-to-linear motion conversion mechanism 33, the reduction ratio of the reducer 32, etc.

[0128] The timing for controlling the holding mechanism 36 is not limited to the above example. Another example of brake control performed by the brake control device 3 is shown in FIG. 16 . In the example of FIG. 16 , the holding mechanism control unit 19 turns on the relay 45 when a certain time has elapsed since the railway vehicle stopped. Steps S11-S18 in FIG. 16 are similar to the processing of steps S11-S18 performed by the brake control device 1 shown in FIG. 6 . The motor target value determination unit 15 acquires the railway vehicle speed from a speed sensor, a train information management device, or the like mounted on the railway vehicle. The motor target value determination unit 15 determines whether the target mechanical braking force is greater than 0 and the railway vehicle is stopped, i.e., whether the state in which the speed is 0 has elapsed for a certain time (step S33). The length of the certain time may be long enough to determine that the railway vehicle is stopped and not due to a sensor error. If the motor target value determiner 15 determines that the target mechanical brake force is greater than 0 and the railway vehicle has been stopped for a certain period of time (step S33; Yes), the brake control device 3 controls the holding mechanism 36 to limit and hold the output shaft 33a (step S32). More specifically, in step S32, the motor target value determiner 15 sends an instruction to the holding mechanism control unit 19 to turn on the relay.

[0129] 17, which is a timing chart corresponding to FIG. 16, time T41 is the time when a certain time has elapsed since the railway vehicle came to a stop at time T4. At time T41, when motor target value determination unit 15 determines that the railway vehicle has been stopped for a certain time, it sends an instruction to hold mechanism control unit 19 to turn on the relay. At time T41, motor target value determination unit 15 sets the target torque and target rotation speed to 0, as shown in graphs C and D.

[0130] The holding mechanism control unit 19 turns on the relay 45 in response to the instruction to turn on the relay, as shown in graph E. As a result, the solenoid of the holding mechanism 36 is electrically connected to the solenoid power supply 44, and a magnetic force of the solenoid is generated. The magnetic force of the solenoid attracts the output shaft 33a, suppressing sliding of the output shaft 33a. With the friction material 50 pressed against the rotating body 60, the holding mechanism 36 holds the output shaft 33a, whose sliding is suppressed, thereby maintaining the pressing force, as shown in graph F. As a result, the railway vehicle is maintained in a stopped state at time T4, as shown in graph G.

[0131] As another example, the holding mechanism control unit 19 may turn on the relay 45 when the target torque is constant and the discrimination unit 13 has determined that the friction material 50 and the rotating body 60 are not separated for a period of time determined according to the characteristics of the motor 31 or when a certain period of time has passed since the railway vehicle came to a stop.

[0132] The configuration of the mechanical brake devices 30, 40 is not limited to the above-described examples. As an example, the mechanical brake device 30 may include a power-assist mechanism 37 that presses the friction material 50 against the rotating body 60 in response to the pressing force of the rotary-to-linear motion conversion mechanism 33, as shown in Fig. 18 . In this case, the load cell 35 may be attached to the power-assist mechanism 37 and measure the force with which the power-assist mechanism 37 presses the friction material 50 against the rotating body 60.

[0133] The booster mechanism 37 is not limited to a lever mechanism, and may be, for example, a toggle mechanism, a link mechanism, etc. The mechanical brake device 40 may be provided with the booster mechanism 37, similar to the mechanical brake device 30.

[0134] The motor 31 is not limited to a three-phase induction motor, but may be any motor as long as the torque and rotation speed are adjustable.

[0135] The configuration of the holding mechanism 36 is not limited to the above example, and may be any mechanism that can be controlled by the brake control device 1-3 and that can allow or suppress sliding of the output shaft 33 a. As an example, the holding mechanism 36 may allow sliding of the output shaft 33 a when the solenoid is energized and suppress sliding of the output shaft 33 a when the solenoid is not energized.

[0136] The brake command output by the operation unit 41 is not limited to a service brake command, but may also include an emergency brake command, a safety brake command, a parking brake command, and the like.

[0137] The target braking force determination unit 11 may acquire a braking command not only from the operation unit 41 but also from a train information management system, an ATS (Automatic Train Stop) device, or the like.

[0138] The core part of the control processing system, which includes the processor 81, the memory 82, and the interface 83, can be realized using a normal computer system rather than a dedicated system. For example, the brake control device 1-3 that executes the above-described processes may be realized by storing and distributing a computer program for executing the above-described operations on a computer-readable recording medium (such as a flexible disk, a CD-ROM (Compact Disc-Read Only Memory), or a DVD-ROM (Digital Versatile Disc-Read Only Memory)), and installing the computer program on a computer. Alternatively, the brake control device 1-3 may be realized by storing the computer program in a storage device of a server device on a communication network and downloading it to a normal computer system.

[0139] When the functions of the brake control device 1-3 are realized by sharing the functions between an OS (Operating System) and an application program, or by collaboration between the OS and an application program, only the application program portion may be stored on a recording medium, storage device, etc.

[0140] It is also possible to superimpose a computer program on a carrier wave and distribute it via a communication network. For example, the computer program may be posted on a bulletin board system (BBS) on the communication network and distributed via the communication network. The computer program may then be started and executed under the control of an OS in the same way as other application programs, thereby executing the above-described processing.

[0141] The hardware configuration of the brake control device 1-3 is not limited to the above example. As an example, as shown in FIG. 19 , the brake control device 1 may be realized by a processing circuit 84. The processing circuit 84 is connected to the operation unit 41, the power supply device 42, and the mechanical brake device 30 via an interface circuit 85. When the processing circuit 84 is dedicated hardware, the processing circuit 84 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 unit of the brake control device 1 may be realized by a separate processing circuit 84, or each unit of the brake control device 1 may be realized by a common processing circuit 84.

[0142] Some of the functions of the brake control devices 1-3 may be realized by dedicated hardware, and other functions may be realized by software or firmware. For example, in the brake control device 1, the drive driver 14 may be realized by a processing circuit 84 shown in Fig. 19, and the target braking force determination unit 11, the target mechanical braking force determination unit 12, and the discrimination unit 13 may be realized by a processor 81 shown in Fig. 5 reading and executing programs stored in a memory 82.

[0143] The present disclosure allows various embodiments and modifications without departing from the broad spirit and scope of the present disclosure. Furthermore, the above-described embodiments are intended to illustrate the present disclosure and do not limit the scope of the present disclosure. That is, the scope of the present disclosure is defined by the claims, not the embodiments. Various modifications made within the scope of the claims and the meaning of equivalent disclosures are considered to be within the scope of the present disclosure.

[0144] 1, 2, 3 Brake control device, 11 Target braking force determination unit, 12 Target mechanical braking force determination unit, 13 Discrimination unit, 14 Drive driver, 15 Motor target value determination unit, 16 Signal generation unit, 17 Power conversion circuit, 18 Current sensor, 19 Holding mechanism control unit, 20 Relay, 30, 40 Mechanical brake device, 31 Motor, 31a Drive shaft, 32 Reducer, 33 Rotation-to-linear motion conversion mechanism, 33a Output shaft, 33b End, 34 Rotation sensor, 35 Load cell, 36 Holding mechanism, 37 Power boosting mechanism, 41 Operation unit, 42 Power supply unit, 43 Main circuit control device, 44 Solenoid power supply, 45 Relay, 50 Friction material, 60 Rotating body, 80 Bus, 81 Processor, 82 Memory, 83 Interface, 84 Processing circuit, 85 Interface circuit, 100, 101, 102 Brake control system.

Claims

1. A brake control device that controls a mechanical brake device that generates a mechanical brake force by pressing a friction material against a rotating body that rotates when a railway vehicle is traveling with the rotational force of a motor with adjustable torque and rotational speed, comprising: a target brake force determination unit that determines a target brake force from a deceleration indicated by a brake command that instructs the railway vehicle to decelerate; a target mechanical brake force determination unit that determines a target mechanical brake force that is a target value of the brake force by the mechanical brake device from the target brake force; a discrimination unit that determines whether the friction material and the rotating body are separated; and a drive driver that converts power supplied from a power supply device into power to be supplied to the motor in accordance with the target torque and a target rotational speed that is determined from the target torque based on a relationship characteristic between the torque and rotational speed of the motor, and supplies the converted power to the motor. A brake control device comprising:

2. The brake control device as described in claim 1, wherein, when the discrimination unit determines that the friction material and the rotating body are separated, the drive driver sets the target torque to the minimum torque of the motor required to bring the friction material closer to the rotating body.

3. The brake control device according to claim 1 or 2, wherein the drive driver sets the target rotation speed to a maximum rotation speed corresponding to the target torque based on the relationship characteristic.

4. A brake control device as described in claim 1, wherein, after the brake command is input to the target braking force determination unit, while the discrimination unit determines that the friction material and the rotating body are separated, the drive driver sets the target torque to a minimum torque of the motor for bringing the friction material closer to the rotating body, sets the target rotation speed to a maximum rotation speed corresponding to the target torque based on the relationship characteristics, converts the power supplied from the power supply unit into power to be supplied to the motor according to the target torque and the target rotation speed, and supplies the converted power to the motor.

5. A brake control device as claimed in any one of claims 1 to 4, wherein the drive driver changes the target torque while maintaining the rate of change of the target torque per unit time within a first target range corresponding to a target value of the rate of change of the deceleration of the railway vehicle.

6. A brake control device as claimed in any one of claims 1 to 5, wherein the drive driver changes the target rotation speed while maintaining the rate of change of the target rotation speed per unit time within a second target range corresponding to a target value of the rate of change of the deceleration of the railway vehicle.

7. A brake control device as described in any one of claims 1 to 6, wherein the discrimination unit discriminates whether or not the friction material is separated from the rotating body based on an integrated value of the motor's rotation speed since the mechanical brake device starts operating and a reference rotation speed determined according to the distance between the friction material and the rotating body when the mechanical brake device is stopped.

8. A brake control device as described in claim 7, wherein the discrimination unit discriminates whether or not the friction material is separated from the rotating body based on the integrated value and the reference rotation speed corresponding to a distance shorter than the distance between the friction material and the rotating body when the mechanical brake device is stopped.

9. A brake control device as described in any one of claims 1 to 6, wherein the discrimination unit is provided in the mechanical brake device and discriminates whether or not the friction material and the rotating body are separated based on a measurement value obtained from a load cell that measures a pressing force, which is the force with which the friction material presses against the rotating body.

10. A brake control device according to any one of claims 1 to 6, wherein the determination unit determines whether or not the friction material and the rotating body are separated from each other based on a current flowing from the drive driver to the motor.

11. A brake control device as described in any one of claims 1 to 10, further comprising an output shaft that slides in response to the rotation of the motor to press the friction material against the rotating body or separate the friction material from the rotating body, and a holding mechanism that limits and holds the output shaft, the holding mechanism control unit controlling the holding mechanism, wherein when the discrimination unit determines that the friction material and the rotating body have not separated, the holding mechanism control unit controls the holding mechanism to limit the sliding of the output shaft.

12. A brake control device as described in claim 11, wherein, when the discrimination unit determines that the friction material and the rotating body are not separated, the holding mechanism control unit limits the sliding of the output shaft, which is made of a magnetic material, by a magnetic force generated when current is applied, and supplies power to the holding mechanism, which allows the output shaft to slide when current is not applied, thereby causing the holding mechanism to limit and hold the sliding of the output shaft.

13. A brake control device as described in claim 11, wherein, when the discrimination unit determines that the friction material and the rotating body are not separated, the holding mechanism control unit allows the output shaft, which is made of a magnetic material, to slide by a magnetic force generated when current is applied, and stops the supply of power to the holding mechanism, which limits the sliding of the output shaft when current is not applied, thereby causing the holding mechanism to limit and hold the sliding of the output shaft.

14. A brake control device as described in any one of claims 11 to 13, wherein the holding mechanism control unit causes the holding mechanism to limit and hold the sliding of the output shaft when the target torque can be regarded as constant and the discrimination unit has determined that the friction material and the rotating body are not separated for a reference time or longer determined in accordance with the characteristics of the motor.

15. A brake control device as described in any one of claims 11 to 14, wherein the holding mechanism control unit controls the holding mechanism to limit and hold the output shaft against sliding when the target mechanical brake force is greater than 0 and the railway vehicle is stopped.

16. A brake control device as described in any one of claims 1 to 15, wherein the target mechanical brake force determination unit obtains regenerative feedback indicating an actual electric brake force generated by consuming electric power generated by a main motor operating as a generator, and calculates the target mechanical brake force from the difference between the actual electric brake force indicated by the regenerative feedback and the target brake force.

17. A brake control system comprising: a brake control device according to any one of claims 1 to 16; and a plurality of mechanical brake devices provided for each wheel of a railway vehicle, the mechanical brake devices being controlled by the brake control device to generate a braking force by pressing a friction material against a rotating body that rotates when the railway vehicle is traveling.

18. A brake control method for controlling a mechanical brake device that generates a mechanical brake force by pressing a friction material against a rotating body that rotates when a railway vehicle is traveling with the rotational force of a motor with adjustable torque and rotational speed, comprising the steps of: calculating a target brake force from a deceleration indicated by a brake command that instructs the railway vehicle to decelerate; calculating a target mechanical brake force that is a target value of the brake force by the mechanical brake device from the target brake force; determining whether or not the friction material is separated from the rotating body; if it is determined that the friction material is separated from the rotating body, setting a value smaller than the torque of the motor for pressing the friction material against the rotating body as the target torque; if it is determined that the friction material is not separated from the rotating body, setting the torque of the motor for obtaining the target mechanical brake force as the target torque of the motor; and controlling a power conversion circuit that converts power supplied from a power supply device into power to be supplied to the motor and supplies the converted power to the motor in accordance with the target torque and a target rotational speed that is determined from the target torque based on the relationship characteristics of the torque and rotational speed of the motor.

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