1
FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
RAIL VEHICLE BRAKE CONTROL DEVICE AND RAIL VEHICLE 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 Kokai 20 Publication No. 2003-291797
Summary of Invention
Technical Problem
[0005] In a case in which the brake shoe is pressed against the wheel to generate a braking force, when a load on the wheel that is represented by a value obtained by 25 multiplying the braking force by a circumferential speed of the wheel is equal to or less than a threshold, a contact surface becomes mirror-finished. The mirror finish of the 3
contact surface causes a reduction in a coefficient of friction. On the other hand, when the load on the wheel is greater than the above-described threshold, the contact surface becomes rough to cause an increase of 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 5 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 depending on the load on the wheel.
[0006] In consideration of such circumstances, an objective of the present disclosure is to reduce the variance in the braking force. 10
Solution to Problem
[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 15 acquirer, a necessary braking force calculator, a generating press force calculator, a friction coefficient calculator, a brake pressure calculator, and an outputter. The command acquirer acquires a brake command indicating a deceleration. When the command 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 20 braking force that is a braking force necessary for obtaining the deceleration. The generating press force calculator calculates a generating press force that is to be generated and is a force pressing the friction member against the rotatable body. The friction coefficient calculator (i) estimates a state of a contact surface between the friction member and the rotatable body based on the generating press force and (ii) calculates a 25 coefficient of friction in accordance with the estimated state of the contact surface. The brake pressure calculator calculates a brake pressure based on the necessary braking force 4
and the coefficient of friction. The outputter (i) adjusts a pressure of fluid supplied from a fluid source in accordance with the brake pressure and (ii) outputs the pressure-adjusted fluid.
Advantageous Effects of Invention
[0008] According to the present disclosure, the coefficient of friction is calculated 5 in accordance with the state of the contact surface estimated based on the generating press force generated by the mechanical brake device, and the brake pressure is calculated in accordance with the calculated coefficient of friction, thereby enabling a reduction of the variance in the braking force.
Brief Description of Drawings 10
[0009] FIG. 1 is a block diagram illustrating an example of a configuration of a rail 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 block diagram illustrating an example of a configuration of a friction 15 coefficient calculator according to the embodiment;
FIG. 4 is a flow chart illustrating one example of braking 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. 20
Description of Embodiments
[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 25 vehicle brake control device according to the embodiment of the present disclosure. A rail vehicle brake control device 1 (referred to as "brake control device" hereinafter) 5
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 froma fluid source 3 and supplies, to a brake cylinder of the mechanical brake device 4, 5 the pressure-adjusted fluid, thereby performing brake control of a rail vehicle. The fluid is, 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 10 brake shoe against a wheel or by pressing a brake pad against a disk. That is, a friction 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 circumferential speed of the wheel. The speed 15 sensor 6 is attached to, for example, an axle of each of a front bogie and a rear bogie of each railcar 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 circumferential speed of the wheel.
[0013] All components of the brake control device 1 that are connected to the fluid 20 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 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 25 each other via an electric circuit, and all components of the brake control device 1 that are connected to the brake setter 2 by the dashed arrows are connected to the brake setter 2 6
via 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 5 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, 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 source3 and then 10 output the fluid to the mechanical brake device 4.
[0015] The brake controller 11 estimates a state of a contact surface between the friction member and the rotatable body based on a generating press force that is being generated by the mechanical brake device 4. The brake controller 11 (i) calculates a coefficient of friction in accordance with the estimated state of the contact surface and (ii) 15 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 state of the contact surface enables a reduction of a variance in the braking force actually generated by the mechanical brake device 4. 20 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 output from the relay valve 14 and (ii) sends a detection value as an electric signal to the brake controller 11. The detection value 25 detected by the pressure sensor 15 can be regarded as a pressure within the brake cylinder included in the mechanical brake device 4. 7
[0016] FIG. 2 is a block diagram illustrating an example of a configuration of the 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 5 acquire the circumferential speed of the wheel, (iv) a generating press force calculator 24 to calculate the generating press force that is a force pressing the friction member against the rotatable body, (v) a friction coefficient calculator 25 to estimate the state of the contact surface and calculate the coefficient of friction in accordance with the estimated state of the contact surface, and (vi) a brake pressure calculator 26 to calculate the brake 10 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 an automatic train control (ATC), an automatic train operation (ATO), or the like. 15
[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 22 may calculate the necessary braking force for each railcar or may calculate the 20 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 load is the detection value of the load detected by the variable load detector 5 is mass-based, the 25 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 8
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 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 yet include the variable load detector 5. 5
[0019] The speed acquirer 23 acquires the circumferential speed of the wheel, for example, from the speed sensor 6 attached to the axle. The speed acquirer 23 may acquire the circumferential speed of the wheel, for example, from a train information management system, the ATC, or the like.
[0020] The generating press force calculator 24 calculates the generating press 10 force that is a force pressing the friction member against the rotatable body. The generating press force calculator 24 calculates the generating press force by multiplying a brake cylinder (BC) pressure detected by the pressure sensor 15 by a pipe diameter of the brake cylinder. Alternatively, the generating press force calculator 24 may calculate the generating press force based on the necessary braking force calculator 22. 15
[0021] The friction coefficient calculator 25 estimates the state of the contact surface based on the generating press force and calculates the coefficient of friction in accordance with the estimated state of the contact surface. The friction coefficient calculator 25 holds a state index that is updated based on the generating press force and that indicates the state of the contact surface, and calculates the coefficient of friction in 20 accordance with the state index. Alternatively, the friction coefficient calculator 25 may calculate the coefficient of friction based on (i) a table that associates the generating press force with the state of the contact surface and (ii) a table that associates the state of the contact surface with the coefficient of friction.
[0022] The brake pressure calculator 26 calculates the brake pressure based on (i) 25 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 brake 9
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 denotes the necessary braking force, a symbol k denotes a constant, and a symbol μ denotes 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 5 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 electric signal indicating the control amount.
B = F / (k • μ) ⋯ (1)
[0023] The electro-pneumatic conversion valve 13 illustrated in FIG. 1 includes, for 10 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 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 15 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 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.
[0024] As expressed by the above equation (1), when the coefficient of friction μ 20 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 brake cylinder. As described above, since the target value B of the brake pressure changes 25 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 10
friction changes. That is, since the brake pressure is calculated based on the coefficient of friction calculated in accordance with the state of the contact surface, the variance in the braking force can be reduced even if the coefficient of friction changes due to the change in the state of the contact surface.
[0025] FIG. 3 is a block diagram illustrating an example of a configuration of the 5 friction coefficient calculator according to the embodiment. The friction coefficient calculator 25 includes a storage 34 in which the state index is stored. The friction coefficient calculator 25 further includes (i)a load calculator 31 to calculate a load amount represented by a value obtained by multiplying the generating press force by the circumferential speed, (ii)an index updater 32 to calculate the state index based on the 10 load amount and then update the state index stored in the storage 34, and (iii) an index converter 33 to calculate the coefficient of friction in accordance with the state index stored in the storage 34. The state index W indicates the state of the contact surface. The state index W is associated with the coefficient of friction μ, and the friction coefficient calculator 25 can calculate the coefficient of friction μ from the state index W. The 15 association between the state index W and the coefficient of friction μ is freely made. In the example of the embodiment, the state index W is associated with the coefficient of friction μsuch that there is a positive correlation between the state index W and the coefficient of friction μ. That is, when the state index W increases, the coefficient of friction μ increases. For an initial value W0 of the state index W, an initial value μ0 of the 20 coefficient of friction μ is determined based on material of the friction member and material of the rotatable body. As described later, the friction coefficient calculator 25 repeatedly calculates the state index W based on the load amount from the state in which the state index W = W0, and calculates a coefficient μ associated with the state index W stored in the storage 34. 25
[0026] The load calculator 31 calculates the load amount Q as represented by the below-described equation (2) when the circumferential speed acquired by the speed 11
acquirer 23 is equal to or greater than a first threshold. In the below-described equation (2), a symbol Fbi denotes the generating press force, a symbol Ri denotes a radius of the wheel, and a symbolωi denotes an angular velocity of the axle. The circumferential velocity of the wheel is represented by Ri • ωi. The load calculator 31 determines whether the rail vehicle is traveling based on whether the circumferential speed is equal to or 5 greater than the first threshold. The first threshold is, for example, 2 km / h.
Q = Fbi • Ri • ωi⋯ (2)
[0027] The generating press force Fbi is expressed by the below-described equation (3). In the below-described equation (3),a symbol Pbc denotes the detection value by the pressure sensor 15, and a symbol S denotes the pipe diameter of the brake cylinder. The 10 generating press force calculator 24 may calculate the generating press force Fbi by using, as the detection value Pbc of the below-described equation (3), the target value B of the brake pressure represented by the above-described equation (1).
Fbi = Pbc • S⋯(3)
[0028] The index updater 32 calculates the state index W based on the load amount 15 Q. For example, when the load amount Q is equal to or greater than a second threshold, the index updater 32 calculates, as an addition value ΔW, a value obtained by multiplying the load amount Q by a first coefficient A as expressed by the below-described equation (4). When the load amount Q is less than the second threshold, the index updater 32 calculates, as the addition value ΔW, a value obtained by multiplying the load amount Q 20 by a second coefficient B different from the first coefficient A in sign, as expressed by the below-described equation (5).For example, A> 0 and B <0. The index updater 32 updates the state index W with a value obtained by adding the addition value ΔW to a value obtained by multiplying the state index W by a third coefficient σ that is a positive number equal to or less than 1, as expressed by the below-described equation (6). For 25 example, the coefficient σ is a positive number less than 1. By setting the coefficient σ to be a positive number less than 1, the state index W decreases depending on the 12
coefficient σ when no brake is applied and Q = 0. As a result, the brake pressure can be calculated while taking into consideration a decrease in the coefficient of friction μ, for example, due to the attachment of fallen leaves, dust or the like to the wheel while the rail vehicle is traveling. The second threshold, the first coefficient A, the second coefficient B, and the third coefficient σ can be determined in accordance with material of the friction 5 member and material of the rotatable body.
ΔW = A • Q⋯ (4)
ΔW = B • Q⋯ (5)
W = σW + ΔW⋯ (6)
[0029] While the command acquirer 21 is acquiring the brake command, the index 10 updater 32 repeats the calculation of the state index W as described above, and at the timing when the command acquirer 21 stops acquiring the brake command, the index updater 32 updates the state index W stored in the storage 34with the state index W calculated as described above. As a result, the control system is suppressed from becoming unstable due to the variation in the coefficient of friction μ during a brake 15 period that is a period during which the brake is applied.
[0030] The index converter 33 calculates the coefficient of friction μ in accordance with the state index W stored in the storage 34. The coefficient of friction μ may be defined as a function that uses the state index W as an argument, or a table may be defined, which associates the coefficient of friction μ with the state index W. The 20 association between the coefficient of friction μ and the state index W can be determined in accordance with a test run of the rail vehicle, simulation or the like. In a case in which the index updater 32 updates the state index W at the end of the brake period, the index converter 33 calculates the coefficient of friction μ in accordance with the state index W updated at the end of the immediately preceding brake period. That is, the brake 25 controller 11 calculates the brake pressure in accordance with the state of the contact surface changed by the brake control in previous brake periods. 13
[0031] FIG. 4 is a flow chart illustrating one example of braking control operation of the rail vehicle brake control device according to the embodiment. While the command 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 S11), the index converter 33 included in the friction coefficient calculator 25 calculates 5 the coefficient of friction μ based on the state index W stored in the storage 34 (step S12). The generating press force calculator 24 calculates the generating press force (step S13). The index updater 32 included in the friction coefficient calculator 25 calculates the state index W based on the load amount Q (step S14). The necessary braking force calculator 22 calculates the necessary braking force based on the deceleration indicated by the brake 10 command and the load on the railcar or the bogie (step S15). 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 S16). The outputter (i) adjusts, in accordance with the brake pressure calculated by the brake pressure calculator 26, the 15 pressure of the fluid supplied from the fluid source 3 and (ii) outputs, to the mechanical brake device 4, the pressure-adjusted fluid, thereby controlling the mechanical brake device 4 (step S17).
[0032] During continuation of the acquisition of the brake command(Yes in step S18), the process returns to step S13 to repeat the above-described steps. When 20 acquisition of the brake command is stopped (No in step S18), the index updater 32 updates the state index W stored in the storage 34 with the state index W calculated by repeating the process of step S14 (Step S19). When the process of step S19 ends, the process of the brake control ends.
[0033] As described above, according to the brake control device 1 according to the 25 present embodiment, the coefficient of friction is calculated in accordance with the state of the contact surface estimated based on the generating press force, and the brake 14
pressure is calculated in accordance with the calculated coefficient of friction, thereby enabling a reduction of the variance in the braking force.
[0034] FIG. 5 is a diagram illustrating an example of a hardware configuration of the brake controller according to the embodiment. The brake controller 11 includes, as a hardware configuration that controls each component, a processor 41, a memory unit 42, 5 and an interface 43. Each of the functions of these devices is realized by the processor 41 executing a program stored in the memory unit 42. The interface 43 is used for connecting each device and establishing communication and may include two or more types of interfaces as may be required. Although FIG. 5 illustrates an example in which the brake controller 11 includes a single processor 41 and a single memory unit 42, 10 multiple processors 41 and multiple memories 42 may cooperate with one another to execute respective functions.
[0035] In addition, the above-described hardware configuration and flowchart are merely examples, and can be changed or modified.
[0036] The central portion that includes the processor 41, the memory unit 42, and 15 the interface 43 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 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 20 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 included in a server device on a communication network and (ii) downloading the computer program onto a normal computer system. 25
[0037] 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 15
controller 11 or the functions of the brake controller 11 are realized by cooperation between the OS and the application program, storage of the application program alone on the recording medium or the storage device is permissible.
[0038] Also, the computer program may be distributed via a communication network by superimposing the computer program on a carrier wave. For example, the 5 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 the OS in the same manner as other application programs so that the above-described processes can be executed. 10
[0039] Embodiments of the present disclosure are not limited to the above-described embodiment. The state index W and the coefficient of friction μ may be associated with each other such that there is a negative correlation there between.
[0040] The foregoing describes some example embodiments for explanatory purposes. Although the foregoing discussion has presented specific embodiments, 15 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 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 20 equivalents to which such claims are entitled.
Reference Signs List
[0041]
1 Brake control device
2 Brake setter 25
3 Fluid source
4 Mechanical brake device 16
5 Variable load detector
6 Speed sensor
11 Brake controller
12 Outputter
13 Electro-pneumatic conversion valve 5
14 Relay valve
15 Pressure sensor
21 Command acquirer
22 Necessary braking force calculator
23 Speed acquirer 10
24 Generating press force calculator
25 Friction coefficient calculator
26 Brake pressure calculator
31 Load calculator
32 Index updater 15
33 Index converter
34 Storage
41 Processor
42 Memory unit
43 Interface 20 17
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 necessary braking force calculator to calculate, upon the command acquirer 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 generating press force calculator to calculate a generating press force that is to be 10 generated and is a force pressing the friction member against the rotatable body;
a friction coefficient calculator to estimate a state of a contact surface between the friction member and the rotatable body based on the generating press force and calculate a coefficient of friction in accordance with the estimated state of the contact surface;
a brake pressure calculator to calculate a brake pressure based on the necessary 15 braking force and the coefficient of friction; and
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, wherein the 20 friction coefficient calculator stores a state index that is updated based on the generating press force, the state index indicating a state of the contact surface, and calculates the coefficient of friction in accordance with the state index.
3. The rail vehicle brake control device according to claim 2, further 25 comprising:
a speed acquirer to acquire a circumferential speed of a wheel of the rail vehicle, 18
wherein
the friction coefficient calculator comprises:
a storage to store the state index;
a load calculator to calculate a load amount represented by a value obtained by multiplying the generating press force by the circumferential speed when the 5 circumferential speed is equal to or greater than a first threshold;
an index updater to calculate the state index based on the load amount and update the state index stored in the storage; and
an index converter to calculate the coefficient of friction in accordance with the state index stored in the storage. 10
4. The rail vehicle brake control device according to claim 3,wherein the index updater calculates
when the load amount is greater than or equal to a second threshold, an addition value by multiplying the load amount by a first coefficient, 15
when the load amount is less than the second threshold, an addition value by multiplying the load amount by a second coefficient having a sign different from a sign of the first coefficient, and
the state index by adding the addition value to a value obtained by multiplying the state index by a third coefficient that is a positive number equal to or less than 1. 20
5. The rail vehicle brake control device according to claim 4, wherein the third coefficient is less than 1.
6. The rail vehicle brake control device according to any one of claims 3 to 5, 25 wherein
while the command acquirer is acquiring the brake command, the index updater 19
repeats calculation of the state index based on the load amount, and
the index updater updates the state index at a timing when the command acquirer stops acquiring the brake command.
7. The rail vehicle brake control device according to any one of claims 1 to 6, 5 further comprising:
a pressure sensor to detect a brake cylinder (BC) pressure indicating a pressure within a brake cylinder included in the mechanical brake device, wherein
the generating press force calculator calculates the generating press force by multiplying the BC pressure detected by the pressure sensor by a pipe diameter of the 10 brake cylinder.
8. The rail vehicle brake control device according to any one of claims 1 to 6,whereinthe generating press force calculator calculates the generating press force based on the necessary braking force calculated by the necessary braking force calculator. 15
9. A rail vehicle brake control method performed bya 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: 20
calculating, upon acquiring a brake command indicating a deceleration, 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;
calculating a generating press force that is a force pressing the friction member against the rotatable body; 25
estimating a state of a contact surface between the friction member and the rotatable body based on the generating press force and calculating a coefficient of friction 20
in accordance with the estimated state of the contact surface;
calculating a brake pressure based on the necessary braking force and the coefficient of friction; and
adjusting, in accordance with the brake pressure, a pressure of fluid supplied from a fluid source and outputting the pressure-adjusted fluid. 5