1
FORM 2
THE PATENTS ACT, 1970
(39 of 1970) & THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13] RAILROAD CAR BRAKE CONTROL DEVICE AND RAILROAD CAR BRAKE CONTROL METHOD; MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3, MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 1008310, JAPAN 5 THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED. 2
DESCRIPTION Technical Field [0001] The present disclosure relates to a rail vehicle brake control device and a rail vehicle brake control method. 5 Background Art [0002] A mechanical brake device mounted on a rail vehicle generates a braking force by pressing a brake shoe against a wheel or by pressing a brake pad against a disk. That is, the braking force is generated by pressing, against a rotatable body that is the wheel or the disc and that rotates when the rail vehicle travels, a friction member that is 10 the brake shoe or the brake pad. [0003] A rail vehicle brake control device disclosed in Patent Literature 1 calculates a required braking force by conventional brake control and outputs a brake control signal to an electro-pneumatic conversion valve. The brake control device generates a target speed pattern from a vehicle speed and a current position of the rail vehicle and performs 15 feedback control to make a speed of the rail vehicle follow a target speed at each time or each position indicated by the target speed pattern. Citation List Patent Literature [0004] Patent Literature 1:Unexamined Japanese Patent Application Publication No. 20 2003-291797 Summary of Invention Technical Problem
[0005] A coefficient of friction of a contact surface between a friction member and a rotatable body changes in accordance with (i) a temperature of the friction member, (ii) 25 a vehicle speed, (iii) a press force that is a force pressing the friction member against the rotatable body, and the like. A braking force is obtained by multiplying the press force 3
by the coefficient of friction. Even if a constant press force is generated by a constant braking operation, the braking force varies with change in the coefficient of friction. During calculation of the required braking force by the conventional brake control disclosed in Patent Literature 1, the variation in the coefficient of friction is not taken into consideration. Therefore, in the conventional brake control, the braking force varies 5 depending on the temperature of the friction member, the vehicle speed, the press force, and the like. [0006] In consideration of such circumstances, an object of the present disclosure is to reduce the variance in the braking force. Solution to Problem 10 [0007] In order to attain the aforementioned objective, a rail vehicle brake control device according to the present disclosure, which is a brake control device for controlling a mechanical brake device that generates a braking force by pressing a friction member against a rotatable body that rotates when a rail vehicle travels, includes a command acquirer, a temperature calculator, a friction coefficient calculator, a necessary braking 15 force calculator, a brake pressure calculator, and an outputter. The command acquirer acquires a brake command indicating a deceleration. The temperature calculator calculates a temperature of the friction member. The friction coefficient calculator calculates, based on the temperature of the friction member, a coefficient of friction of a contact surface between the friction member and the rotatable body. When the command 20 acquirer acquires the brake command, the necessary braking force calculator calculates, based on the deceleration and a load on a railcar or a bogie, a necessary braking force that is a braking force necessary for obtaining the deceleration. The brake pressure calculator calculates a brake pressure based on the necessary braking force and the coefficient of friction. The outputter (i) adjusts a pressure of fluid supplied from a fluid source in 25 accordance with the brake pressure and (ii) outputs the pressure-adjusted fluid. Advantageous Effects of Invention 4
[0008] According to the present disclosure, the brake pressure is calculated in accordance with the coefficient of friction calculated based on the temperature of the friction member, thereby enabling a reduction of the variance in the braking force. Brief Description of Drawings [0009] FIG. 1 is a block diagram illustrating an example of a configuration of a rail 5 vehicle brake control device according to an embodiment of the present disclosure; FIG. 2 is a block diagram illustrating an example of a configuration of a brake controller according to the embodiment; FIG. 3 is a diagram illustrating an example of a table for calculating a coefficient of friction according to the embodiment; 10 FIG. 4 is a flow chart illustrating one example of brake control operation of the rail vehicle brake control device according to the embodiment; and FIG. 5 is a diagram illustrating an example of a hardware configuration of the brake controller according to the embodiment. Description of Embodiments 15 [0010] An embodiment of the present disclosure is described below in detail with reference to drawings. Components that are the same or equivalent are assigned the same reference signs throughout the drawings.
[0011] FIG. 1 is a block diagram illustrating an example of a configuration of a rail vehicle brake control device according to the embodiment of the present disclosure. A 20 rail vehicle brake control device 1 (referred to as "brake control device" hereinafter) acquires a brake command and controls, in accordance with the acquired brake command, a mechanical brake device 4 that is operated by fluid. In an example of the embodiment, the brake control device 1 acquires the brake command from a brake setter 2 provided, for example, in a cab. The brake control device 1 adjusts a pressure of fluid supplied from 25 a fluid source 3 and supplies the pressure-adjusted fluid to a brake cylinder of the mechanical brake device 4, thereby performing brake control of a rail vehicle. The fluid is, 5
for example, air, oil or the like. In the example of the embodiment, air is used as the fluid. The fluid source 3 is, for example, an air reservoir tank filled with air compressed by an air compressor. [0012] The mechanical brake device 4 generates a braking force by pressing a brake shoe against a wheel or by pressing a brake pad against a disk. That is, a friction 5 member of the mechanical brake device 4 such as a brake shoe or a brake pad is pressed against a rotatable body such as a wheel or a disk that rotates when the rail vehicle travels, thereby generating a braking force. A variable load detector 5 detects a load on a railcar or a bogie. A speed sensor 6 detects a speed of the rail vehicle. The speed sensor 6 is attached to, for example, an axle of each of a front bogie and a rear bogie of each railcar 10 of the rail vehicle. That is, four speed sensors 6 are attached to each railcar. The speed sensor 6 detects, based on a rotational frequency of the axle, the speed of the rail vehicle. [0013] All components of the brake control device 1 that are connected to the fluid source 3 by solid lines in FIG. 1are connected to the fluid source 3via air piping, and all components of the brake control device 1 that are connected to the mechanical brake 15 device 4 by solid lines in FIG. 1 are connected to the mechanical brake device 4 via air piping. In FIG. 1, dashed arrows indicate electric signals, and all components of the brake control device 1 that are connected to each other by the dashed arrows are connected to each other via an electric circuit, and all components of the brake control device 1 that are connected to a brake setter 2 by the dashed arrows are connected to the brake setter 2 via 20 an electric circuit.
[0014] The brake control device 1 includes (i) a brake controller 11 to output, based on the brake command, a control signal indicating a brake pressure, (ii) an outputter 12 to adjust, in accordance with the brake pressure, the pressure of the fluid supplied from the fluid source 3 and output the pressure-adjusted fluid, and (iii) a pressure sensor 15 to 25 detect the pressure of the fluid output by the outputter 12. The outputter 12 includes (i) an electro-pneumatic conversion valve 13 to adjust, in accordance with the control signal, 6
the pressure of the fluid supplied from the fluid source 3 and then output the fluid and (ii) a relay valve 14 to adjust, in accordance with the output by the electro-pneumatic conversion valve 13, the pressure of the fluid supplied from the fluid source 3 and then output the fluid to the mechanical brake device 4. [0015] The brake controller 11 (i) calculates a coefficient of friction of a contact 5 surface between a friction member and a rotatable body in accordance with a temperature of the friction member and (ii) calculates the brake pressure based on the calculated coefficient of friction. The brake controller 11 performs feedback control in accordance with a detection value detected by the pressure sensor 15. The calculation of the brake pressure based on the coefficient of friction calculated in accordance with the temperature 10 of the friction member enables a reduction of a variance in the braking force actually generated by the mechanical brake device 4. The control signal that is an electrical signal can be converted into a pneumatic pressure signal by the use of the electro-pneumatic conversion valve 13. The relay valve 14 is used for improving the responsiveness of the mechanical brake device 4. The pressure sensor 15 (i) detects the pressure of the fluid 15 output from the relay valve 14 and (ii) sends a detection value as an electric signal to the brake controller 11. The detection value detected by the pressure sensor 15 can be regarded as a pressure within the brake cylinder included in the mechanical brake device 4.
[0016] FIG. 2 is a block diagram illustrating an example of a configuration of the 20 brake controller according to the embodiment. The brake controller 11 includes (i) a command acquirer 21 to acquire the brake command, (ii) a necessary braking force calculator 22 to calculate a necessary braking force that is a braking force necessary to obtain the deceleration indicated by the brake command, (iii) a speed acquirer 23 to acquire the speed of the rail vehicle, (iv) a temperature calculator 24 to calculate the 25 temperature of the friction member of the mechanical brake device 4, (v) a friction coefficient calculator 25 to calculate the coefficient of friction of the contact surface 7
between the friction member of the mechanical brake device 4 and the rotatable body, and (vi) a brake pressure calculator 26 to calculate the brake pressure. [0017] The command acquirer 21 acquires, from the brake setter 2,the brake command indicating the deceleration. The command acquirer 21 may acquire the brake command from automatic train control (ATC), automatic train operation (ATO), or the 5 like. [0018] The necessary braking force calculator 22 calculates the necessary braking force that is a braking force necessary to obtain the deceleration indicated by the brake command. The necessary braking force calculator 22 sends the calculated necessary braking force to the brake pressure calculator 26. The necessary braking force calculator 10 22 may calculate the necessary braking force for each railcar or may calculate the necessary braking force for each bogie. The necessary braking force calculator 22 calculates the necessary braking force for each railcar or each bogie based on the brake command and the load on the railcar or the bogie. Since the load is equal to a value obtained by multiplying mass by gravitational acceleration, in a case in which the 15 detection value of the load detected by the variable load detector 5 is mass-based, the necessary braking force can be calculated by the product of the deceleration times the detection value of the load. For example, when the deceleration indicated by the brake command is represented by a symbol α and the load of each railcar detected by the variable load detector 5 is represented by symbols W1, W2, ..., and Wk, the necessary 20 braking force of each railcar is represented by symbols α•W1, α•W2,..., and α•Wk. A load on a railcar or a bogie provided with the variable load detector 5 may be used as a load on a railcar or a bogie that does not include the variable load detector 5. [0019] The speed acquirer 23 acquires the speed of the rail vehicle, for example, from the speed sensor 6 attached to the axle. The speed acquirer 23 may acquire the speed 25 of the rail vehicle, for example, from a train information management system, the ATC, or the like. 8
[0020] The temperature calculator 24 calculates the temperature of the friction member of the mechanical brake device 4.In the example illustrated in FIG. 2, the temperature calculator 24 calculates the temperature of the friction member by estimating the temperature of the friction member based on the speed of the rail vehicle acquired by the speed acquirer 23 and the detection value detected by the pressure sensor 15.For 5 example, a filling time that is a time for filling the brake cylinder with the pressure-adjusted fluid can be estimated from an initial speed that is a speed of the rail vehicle at a time when the command acquirer 21 acquires the first brake command after a state in which the command acquirer does not acquire any brake commands. The temperature of the friction member that is increased by operation of the mechanical brake 10 device 4 can be estimated from the detection value of the pressure sensor 15 and the refilling time for the brake cylinder. For example, the temperature calculator 24 stores a temperature estimation table in which the temperature of the friction member is determined in accordance with the vehicle speed and the pressure of the brake cylinder of the mechanical brake device 4. Values listed in the temperature estimation table are 15 determined in accordance with actual measurement values, simulation values, or the like. The temperature calculator 24 estimates the temperature of the friction member based on the initial speed, the detection value by the pressure sensor 15, and the temperature estimation table. The temperature calculator 24 may detect the temperature of the friction member of the mechanical brake device 4 using a temperature sensor. 20
[0021] Also, for example, the temperature calculator 24 may estimate, based on (i) an elapsed time since the end of the latest brake control operation, (ii) heat release characteristics, or the like, the temperature of the friction member at the start of brake control. An equation for estimating the temperature of the friction member at the start of the brake control can be derived in accordance with the actual measurement values, the 25 simulation values, or the like. The temperature calculator 24 may estimate the temperature of the friction member based on (i) the temperature of the friction member at 9
the start of the brake control, (ii) the initial speed, and (iii) the detection value by the pressure sensor 15.The influence of outside air temperature can be considered to be sufficiently small since an amount of change in the outside air temperature is small as compared with the tolerable error in the temperature of the friction member during calculation of the coefficient of friction, and calculation of the coefficient of friction is 5 described later. [0022] The friction coefficient calculator 25 calculates, based on the temperature of the friction member, the coefficient of friction of the contact surface between the friction member and the rotatable body. In the example illustrated in FIG. 2, the friction coefficient calculator 25 calculates the coefficient of friction based on the temperature of 10 the friction member and the speed of the rail vehicle. For example, the friction coefficient calculator 25 calculates the coefficient of friction based on (i) the temperature of the friction member and (ii) the initial speed that is the speed of the rail vehicle at the time when the command acquirer acquires the first brake command after the state in which the command acquirer 21 is not acquiring the brake command. For example, the friction 15 coefficient calculator 25 stores a friction coefficient calculation table in which friction coefficients are determined in accordance with the temperature of the friction member and the speed of the rail vehicle. Values listed in the friction coefficient calculation table are determined in accordance with the actual measurement values, the simulation values, or the like. The friction coefficient calculator 25 estimates the temperature of the friction 20 material based on the temperature of the friction member, the initial speed, and the friction coefficient calculation table.
[0023] The brake pressure calculator 26 calculates the brake pressure based on (i) the necessary braking force calculated by the necessary braking force calculator 22 and (ii) the coefficient of friction calculated by the friction coefficient calculator 25. The 25 brake pressure calculator 26 calculates a target value B of the brake pressure as expressed by the below-described equation (1). In the below-described equation (1), a symbol F 10
denotes the necessary braking force, a symbol k denotes a constant, and a symbol μdenotes the coefficient of friction. The brake pressure calculator 26 (i) performs feedback control based on the target value B of the brake pressure and the detection value by the pressure sensor 15 and (ii) calculates a control amount of the brake pressure. The brake pressure calculator 26 outputs, to the electro-pneumatic conversion valve 13, an 5 electric signal indicating the control amount. B = F / (k • μ) ⋯ (1) [0024] While the command acquirer 21 is continuously acquiring the brake command, that is, during a brake period that is a period during which the brake is applied, the brake pressure calculator 26 calculates, using the coefficient of friction calculated by 10 the friction coefficient calculator 25 based on, independently of a change in the brake command, the temperature of the friction member and the initial speed, the target value B of the brake pressure and the control amount of the brake pressure. The coefficient of friction is calculated for each brake period, and the brake control is performed using the same coefficient of friction during the brake period, thereby accurately responding to a 15 brake operation occurring at the brake setter 2 together with reducing of the variance in the braking force. [0025] The electro-pneumatic conversion valve 13 illustrated in FIG. 1 includes, for example, (i) an AV solenoid valve that is a solenoid valve for supplying air and (ii) an RV solenoid valve that is a solenoid valve for discharging air. The electro-pneumatic 20 conversion valve 13 (i) adjusts, in accordance with the electrical signal indicating the control amount of the brake pressure output by the brake controller 11, the pressure of the fluid supplied from the fluid source 3 and (ii) outputs the pressure-adjusted fluid to the relay valve 14. As described above, the relay valve 14 (i)adjusts, in accordance with the output of the electro-pneumatic conversion valve 13, the pressure of the fluid supplied 25 from the fluid source 3 and (ii) outputs the pressure-adjusted fluid to the mechanical brake device 4. As a result, the mechanical brake device 4 is operated. 11
[0026] As expressed by the above equation (1), when the coefficient of friction μ increases, the target value B of the brake pressure decreases. On the other hand, when the coefficient of friction μ decreases, the target value B of the brake pressure increases. The braking force generated by the mechanical brake device 4 is proportional to a value obtained by multiplying the coefficient of friction μ by the brake pressure within the 5 brake cylinder. As described above, since the target value B of the brake pressure changes in inverse proportion to the coefficient of friction μ, a variance in the braking force generated by the mechanical brake device 4 can be reduced even if the coefficient of friction changes. That is, since the brake pressure is calculated based on the coefficient of friction in accordance with the temperature of the friction member, the variance in the 10 braking force can be reduced even if the temperature of the friction member changes. [0027] FIG. 3 isa diagram illustrating an example of a table for calculating a coefficient of friction according to the embodiment. The friction coefficient calculator 25 may retain the friction coefficient calculation table in which the coefficient of friction is determined in accordance with (i) multiple temperature ranges of the friction member 15 and (ii) multiple speed ranges of the rail vehicle. The friction coefficient calculator 25 calculates the coefficient of friction based on (i) the temperature of the friction member, (ii) the speed of the rail vehicle, and (iii) the table illustrated in FIG. 3. In the example illustrated in FIG. 3, the number of the set temperature ranges is n, and the number of the set speed ranges is m. The numbers n and m are any positive integers equal to or greater 20 than two. Also, the temperature ranges T1. T2, ..., and Tn and the speed ranges V1, V2, ..., and Vm are freely selected.
[0028] For example, in a case in which a temperature calculated by the temperature calculator 24 is included in the temperature range T1 and a speed of the rail vehicle acquired by the speed acquirer 23 is included in the speed range V1, the friction 25 coefficient calculator 25 calculates a coefficient of friction μ11. In a case in which the temperature of the friction member is constant, the faster the speed of the rail vehicle, the 12
smaller the coefficient of friction. That is, when V1 μ12>...>μ1m. When the speed of the rail vehicle is constant, the higher the temperature, the smaller the coefficient of friction. That is, when T1 < T2 <••• μ21>...>μn1. [0029] FIG. 4 is a flow chart illustrating one example of brake control operation of the rail vehicle brake control device according to the embodiment. While the command 5 acquirer 21 is not acquiring the brake command (No in step S11), the process of step S11 is repeated. When the command acquirer 21 acquires the brake command (Yes in step S12), the friction coefficient calculator 25 calculates, based on the temperature of the friction member, the coefficient of friction of the contact surface between the friction member and the rotatable body (step S12). The necessary braking force calculator 22 10 calculates the necessary braking force based on the deceleration indicated by the brake command and the load on the railcar or the bogie (step S13). The brake pressure calculator 26 calculates the brake pressure based on the necessary braking force calculated by the necessary braking force calculator 22 and the coefficient of friction calculated by the friction coefficient calculator 25 (step S14). The outputter (i) adjusts, in 15 accordance with the brake pressure calculated by the brake pressure calculator 26, the pressure of the fluid supplied from the fluid source 3 and (ii) outputs the pressure-adjusted fluid to the mechanical brake device 4, thereby controlling the mechanical brake device 4 (step S15).During continuation of the acquisition of the brake command (Yes in step S16), the process returns to step S13 to repeat the above-described 20 steps. In a case in which the brake command is not acquired (No in step S16), the process of the brake control ends. [0030] As described above, according to the brake control device 1 according to the present embodiment, the brake pressure is calculated based on the coefficient of friction calculated based on the temperature of the friction member, thereby enabling reducing of 25 the variance in the braking force.
[0031] FIG. 5 is a diagram illustrating an example of a hardware configuration of 13
the brake controller according to the embodiment. The brake controller 11 includes, as a hardware configuration that controls each component, a processor 31, a memory 32, and an interface 33. Each of the functions of these devices is realized by the processor 31 executing a program stored in the memory 32. The interface 33 is used for connecting each device and establishing communication and may include two or more types of 5 interfaces as may be required. Although FIG. 5 illustrates an example in which the brake controller 11 includes a single processor 31 and a single memory 32, multiple processors 31 and multiple memories 32 may cooperate with one another to execute respective functions. [0032] In addition, the above-described hardware configuration and flowchart are 10 merely examples, and can be changed or modified. [0033] The central portion that includes the processor 31, the memory 32, and the interface 33 to perform control processing can be realized using a normal computer system without using a dedicated system. For example, the brake controller 11 may be configured to execute the above-described processes by (i) storing, on a computer 15 readable recording medium (a flexible disc, a compact disc-read only memory (CD-ROM), digital versatile disc-read only memory (DVD-ROM) or the like, a computer program for executing the above-described processes, (ii) distributing the medium, and (iii) installing the computer program in a computer. Alternatively, the brake controller 11 may be configured by (i) storing the computer program in a storage device that is 20 included in a server device on a communication network and (ii) downloading the computer program onto a normal computer system. [0034] Also, for example, in a case in which an operating system (OS) and an application program share with each other in realizing the functions of the brake controller 11 or the functions of the brake controller 11 are realized by cooperation 25 between the OS and the application program, storage of the application program alone on the recording medium or the storage device is permissible 14
[0035] Also, the computer program may be distributed via a communication network by superimposing the computer program on a carrier wave. For example, the computer program may be posted on a bulletin board system (BBS) on a communication network, and the computer program may be distributed via the communication network. Additionally, the computer program may be launched and executed under the control of 5 the OS in the same manner as other application programs so that the above-described processes can be executed. [0036] Embodiments of the present disclosure are not limited to the above-described embodiment. The temperature calculator 24 may calculate the temperature of the friction member based on a function instead of the use of the 10 temperature estimation table. [0037] The foregoing describes some example embodiments for explanatory purposes. Although the foregoing discussion has presented specific embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the broader spirit and scope of the invention. Accordingly, the 15 specification and drawings are to be regarded in an illustrative rather than a restrictive sense. This detailed description, therefore, is not to be taken in a limiting sense, and the scope of the invention is defined only by the included claims, along with the full range of equivalents to which such claims are entitled. Reference Signs List 20 [0038] 1 Brake control device 2 Brake setter 3 Fluid source 4 Mechanical brake device 25 5 Variable load detector 6 Speed sensor 15
11 Brake controller 12 Outputter 13 Electro-pneumatic conversion valve 14 Relay valve 15 Pressure sensor 5 21 Command acquirer 22 Necessary braking force calculator 23 Speed acquirer 24 Temperature calculator 25 Friction coefficient calculator 10 26 Brake pressure calculator 31 Processor 32 Memory 33 Interface 16
CLAIMS
1. A rail vehicle brake control device for controlling a mechanical brake device that generates a braking force by pressing a friction member against a rotatable body that rotates when a rail vehicle travels, the rail vehicle brake control device comprising: a command acquirer to acquire a brake command indicating a deceleration; 5 a temperature calculator to calculate a temperature of the friction member; a friction coefficient calculator to calculate, based on the temperature of the friction member, a coefficient of friction of a contact surface between the friction member and the rotatable body; a necessary braking force calculator to calculate, upon the command acquirer 10 acquiring the brake command, a necessary braking force based on the deceleration and a load on a railcar or a bogie, the necessary braking force being a braking force necessary for obtaining the deceleration; a brake pressure calculator to calculate a brake pressure based on the necessary braking force and the coefficient of friction; and 15 an outputter to adjust, in accordance with the brake pressure, a pressure of fluid supplied from a fluid source and output the pressure-adjusted fluid.
2. The rail vehicle brake control device according to claim 1, further comprising a speed acquirer to acquire a speed of the rail vehicle, wherein 20 the temperature calculator estimates, based on the speed of the rail vehicle and a pressure within a brake cylinder included in the mechanical brake device, the temperature of the friction member to calculate the temperature of the friction member.
3. The rail vehicle brake control device according to claim 1 or2, further 25 comprising a speed acquirer to acquire a speed of the rail vehicle, wherein
the friction coefficient calculator calculates, based on the temperature of the 17
friction member and the speed of the rail vehicle, the coefficient of friction of the contact surface between the friction member and the rotatable body.
4. The rail vehicle brake control device according to claim 3,wherein the friction coefficient calculator calculates the coefficient of friction based on (i) 5 the temperature of the friction member and (ii) an initial speed that is a speed of the rail vehicle at a time when the command acquirer acquires a first brake command after a state in which the command acquirer does not acquire any brake commands, and during continuation of acquisition of the brake command, the brake pressure calculator calculates the brake pressure, independently of a change in the brake command, 10 using the coefficient of friction calculated by the friction coefficient calculator based on the temperature of the friction member and the initial speed.
5. The rail vehicle brake control device according to claim 3 or4, wherein the friction coefficient calculator retains a table in which the coefficient of friction 15 is determined in accordance with multiple temperature ranges of the friction member and multiple speed ranges of the rail vehicle, and the friction coefficient calculator calculates the coefficient of friction based on the temperature of the friction member, the speed of the rail vehicle, and the table. 20
6. A rail vehicle brake control method performed by a rail vehicle brake control device for controlling a mechanical brake device that generates a braking force by pressing a friction member against a rotatable body that rotates when a rail vehicle travels, the rail vehicle brake control method comprising: calculating a temperature of the friction member; 25 calculating, based on the temperature of the friction member, a coefficient of friction of a contact surface between the friction member and the rotatable body; 18
calculating, upon acquiring a brake command, a necessary braking force based on a deceleration indicated by the brake command and a load on a railcar or a bogie, the necessary braking force being a braking force necessary for obtaining the deceleration; calculating a brake pressure based on the necessary braking force and the coefficient of friction; and 5 adjusting, in accordance with the calculated brake pressure, a pressure of fluid supplied from a fluid source to output the pressure-adjusted fluid.