A hydraulic braking system for railway vehicles

Abstract

A hydraulic braking system for railway vehicles, comprising a first hydraulic motor, a control valve group, a second hydraulic motor and an energy conversion device. The first hydraulic motor, the control valve group and the second hydraulic motor form a closed hydraulic transmission system. The two ends of the closed system are respectively connected to the vehicle running wheelset and the energy conversion device. The control valve group is connected in parallel with the first hydraulic motor and the second hydraulic motor. The first hydraulic motor is connected to the vehicle running wheelset, and the second hydraulic motor is connected to the energy conversion device. The control valve group includes a communication valve and a two-way overflow valve group for restricting the pressures of two oil ports, namely port A and port B, on the first hydraulic motor. It further includes a makeup oil pump for supplying oil to the closed system and providing control oil for the communication valve in the control valve group. The hydraulic braking device provided by the present invention can absorb the kinetic energy of the vehicle through energy conversion, so as to apply a controllable, continuous and stable braking force to the vehicle, which is particularly suitable for the working conditions of the vehicle going down long and steep slopes, and improves the safety of the vehicle.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydraulic control, and particularly relates to a hydraulic braking system for railway vehicles. Background Art

[0002] At present, the standard braking method for railway vehicles is wheel brake, which generates braking force by pressing the brake shoe against the wheel flange with the positive pressure generated by the brake cylinder to generate frictional force. During braking, the kinetic energy of the vehicle is converted into heat energy of the brake shoe and the wheel. This kind of braking has a disadvantage that when braking for a long time, the brake shoe and the wheel will generate heat due to long-term friction, causing the temperature of the brake shoe to rise until the brake shoe melts, which will cause the vehicle to lose braking and result in major safety accidents. The railway standard stipulates that the railway line gradient is 0 - 30‰. At present, there are quite a lot of long and steep slopes in the western region of China. When the vehicle runs downhill on a long and steep slope, it can only control the speed through wheel braking. The braking is persistent and frequent, resulting in too fast temperature rise and too high temperature of the brake shoe, overloading of the vehicle's heat load, low braking efficiency, and at the same time bringing a series of problems such as forced parking to cool the brake shoe occupying the skylight time and too fast wear of the brake shoe, seriously affecting safe parking.

[0003] With the rapid development of China's railway industry, especially the rapid expansion of the central and western lines, the line conditions are becoming more and more complex, and the long and steep slope lines are showing an explosive increase. Therefore, it is necessary to develop a braking device suitable for railway vehicles operating on long and steep slopes. Summary of the Invention

[0004] The present invention can generate controllable, continuous and stable braking force during vehicle operation. The braking method of a hydraulic braking system for railway vehicles provided by the present invention can convert the kinetic energy of the vehicle into other forms of energy for dissipation or storage, thereby reducing the workload of the vehicle's air braking and improving the safety of vehicle operation.

[0005] The technical solution of the present invention is as follows:

[0006] A hydraulic braking system for railway vehicles includes a first hydraulic motor, a second hydraulic motor, a control valve group, and an energy conversion device. The first hydraulic motor, the control valve group, and the second hydraulic motor form a closed system. The control valve group is connected in parallel with the first hydraulic motor and the second hydraulic motor. The first hydraulic motor is connected to the vehicle running wheel pair, and the second hydraulic motor is connected to the energy conversion device; the control valve group includes a communication valve and a two-way overflow valve group for restricting the pressure of two oil ports, namely port A and port B, on the first hydraulic motor; it also includes a makeup oil pump for replenishing oil to the closed system and providing control oil for the communication valve in the control valve group.

[0007] The first hydraulic motor is connected to the vehicle running wheel pair through a gearbox on the axle, and the gearbox on the axle has a function of disengaging and engaging gears; the makeup oil pump is connected to the tail of the hydraulic motor, or the makeup oil pump is connected to the vehicle prime mover.

[0008] Port A of the first hydraulic motor is connected to Port A1 of the control valve group, Port B of the first hydraulic motor is connected to Port B1 of the control valve group, Port A2 of the control valve group is connected to Port A3 of the second hydraulic motor, Port B2 of the control valve group is connected to Port B3 of the second hydraulic motor, and the energy conversion device is connected to the second hydraulic motor through a coupling; The two-way overflow valve group of the control valve group includes two high-pressure overflow oil replenishing valves. Port A6 of one high-pressure overflow oil replenishing valve is connected to Port A1 of the control valve group, Port A4 of the other high-pressure overflow oil replenishing valve is connected to Port B1 of the control valve group, Port B6 of one high-pressure overflow oil replenishing valve, Port B4 of the other high-pressure overflow oil replenishing valve and Port P of the communication valve are connected, Port A5 of the communication valve is connected to Port A2 of the control valve group, and Port B5 of the communication valve is connected to Port B2 of the control valve group.

[0009] The inlet of the oil replenishing pump is connected to the oil suction port of the hydraulic oil tank. The outlet of the oil replenishing pump is connected to Port P1 of the oil replenishing overflow valve, Port B4 return oil port, Port B6 return oil port of the high-pressure oil replenishing overflow valve and Port P of the communication valve. Port T1 of the oil replenishing overflow valve and Port T of the communication valve are both connected to the hydraulic oil tank. The hydraulic oil tank is used to store hydraulic oil, provide oil suction, and receive return oil.

[0010] A one-way rectifying valve group is provided between the control valve group and the second hydraulic motor. The function of the one-way rectifying valve group is that no matter whether Port A1 of the control valve group is at high pressure and Port B1 is at low pressure or Port A1 is at low pressure and Port B1 is at high pressure, the one-way rectifying valve group will make Port A8 at high pressure and Port B8 at low pressure. The one-way rectifying valve group includes four one-way valves, two of which are installed back-to-back as a group, and the other two are installed facing each other as a group. The two groups of one-way valves are connected in parallel to form the one-way rectifying valve group.

[0011] Both the first hydraulic motor and the second hydraulic motor are electro-hydraulic proportional motors, and the energy conversion device is a hydraulic retarder. When the first hydraulic motor rotates clockwise or counterclockwise following the axle, the control valve group can control the maximum pressure of the closed system and the communication or disconnection of the main oil circuit. The main oil circuit refers to the oil circuit between Port A and Port A3 and the oil circuit between Port B3 and Port B.

[0012] The first hydraulic motor rotates clockwise or counterclockwise following the vehicle running wheelset; Both the first hydraulic motor and the second hydraulic motor can adjust the motor displacement during operation, and the adjustment method can be electric control or hydraulic control; The first hydraulic motor converts the kinetic energy of the vehicle into hydraulic energy; The energy conversion device converts the hydraulic energy of the closed system into other forms of energy for storage or dissipation.

[0013] The high-pressure overflow oil replenishing valve defines the pressure of the system, and the communication valve controls the communication and cut-off of the two main oil circuits of the hydraulic motor; the action of the communication valve is controlled by the electromagnet DT1 on the valve.

[0014] The oil ports A1, A2, A5, and A6 on the control valve group are in communication, and the oil ports B1, B2, B5, and A4 are in communication.

[0015] A railway vehicle hydraulic braking system includes an electro-hydraulic proportional motor I, an oil replenishing pump, a control valve group, a one-way rectifying valve group, an electro-hydraulic proportional motor II, and a hydrodynamic retarder; the electro-hydraulic proportional motor I is connected to the vehicle running wheelset through an axle gearbox, and the oil replenishing pump is connected to the tail of the electro-hydraulic proportional motor I; the control valve group includes two high-pressure overflow oil replenishing valves, a communication valve, and a shuttle valve; the port A of the electro-hydraulic proportional motor I is connected to the port A1 of the control valve group, the A2 of the control valve group is connected to the port A7 of the one-way rectifying valve group, and the port A8 of the one-way rectifying valve group is connected to the port A3 of the electro-hydraulic proportional motor II; the port B of the electro-hydraulic proportional motor I is connected to the port B1 of the control valve group, the B2 of the control valve group is connected to the port B7 of the one-way rectifying valve group, and the port B8 of the one-way rectifying valve group is connected to the port B3 of the electro-hydraulic proportional motor II; the oil outlet of the oil replenishing pump is connected to the P1 port of the oil replenishing overflow valve, and the P1 port of the oil replenishing overflow valve is simultaneously connected to the B4 and B6 ports of the two high-pressure overflow oil replenishing valves, the S1 port of the shuttle valve, and the S2 port of the shuttle valve is connected to the P2 port of the one-way rectifying valve group, and the S port of the shuttle valve is connected to the P port of the communication valve; the hydrodynamic retarder is connected to the electro-hydraulic proportional motor II through a coupling; the inlet of the oil replenishing pump is connected to the oil suction port of the hydraulic oil tank, and the T1 port of the oil replenishing overflow valve, the T port of the communication valve, the oil drain ports of the electro-hydraulic proportional motor I and the electro-hydraulic proportional motor II are all connected to the hydraulic oil tank. The function of the shuttle valve is to compare the oil replenishing oil and the high-pressure oil in the main oil circuit of the closed system, and take the higher one as the control oil of the communication valve. The main oil circuit refers to the oil circuit between the ports A - A3 and the oil circuit between the ports B3 - B. The oil coming out of the oil replenishing pump is called the oil replenishing oil.

[0016] The working principle of the railway vehicle hydraulic braking device of the present invention is as follows:

[0017] Condition 1: Driving forward on a long and steep downhill slope

[0018] The vehicle moves forward, and the axle gearbox drives the first hydraulic motor 2 to work. Assume that at this time, port A of the first hydraulic motor 2 in the closed system is the oil outlet, and port B is the oil inlet. When hydraulic braking is not required, DT1 of the communication valve 7 loses power, and the communication valve 7 is in the open state. Ports A and B of the first hydraulic motor 2 are in a communicating state, that is, hydraulic oil flows out from port A of the first hydraulic motor 2, and after passing through ports A5 and B5 of the communication valve 7 on the control valve group 3, it directly returns to port B of the first hydraulic motor 2 without driving the second hydraulic motor 4. At this time, the load of the hydraulic system is basically 0. When the vehicle control system sends a signal for hydraulic braking to work, the electromagnet DT1 on the communication valve 7 is energized, and the communication valve 7 closes, cutting off the communication state between ports A and B of the first hydraulic motor 2. At this time, the hydraulic oil flowing out from port A of the hydraulic motor 2 passes through ports A1 and A2 of the control valve group 3 and then reaches port A3 of the second hydraulic motor 4. Then, it flows out from port B3 of the second hydraulic motor 4 to port B2 of the control valve group 3, passes through the internal channel of the control valve group 3 to port B1, and finally reaches port B of the hydraulic motor 2 through a pipeline, thus completing the circulation of the entire oil circuit. At this time, the energy conversion device is the load of the hydraulic system, and the magnitude of the load determines the pressure of the hydraulic system. At this time, the torque generated by the system pressure difference of the first hydraulic motor 2 acts on the vehicle running wheelset 1 through the connecting device, finally forming a braking force for the vehicle, and the magnitude of the braking force is determined by the pressure of the system. At the same time, the energy conversion device 5 converts the energy of the hydraulic system into other forms of energy for dissipation or storage.

[0019] Condition 2: Moving backward on a long and steep slope

[0020] The vehicle moves forward, and the axle gearbox drives the first hydraulic motor 2 to work. Assume that at this time, port B of the first hydraulic motor 2 in the closed system is the oil outlet, and port A is the oil inlet. When hydraulic braking is not required, the solenoid DT1 of the communication valve 7 loses power, the communication valve 7 is in the open state, and ports A and B of the first hydraulic motor 2 are in a communicating state, that is, hydraulic oil flows out from port A of the first hydraulic motor 2, and directly returns to port B of the first hydraulic motor 2 after passing through ports A5 and B5 of the communication valve 7 on the control valve group 3, without driving the second hydraulic motor 4. At this time, the load of the hydraulic system is basically 0. When the vehicle control system sends a signal for hydraulic braking to work, the solenoid DT1 on the communication valve 7 is energized, the communication valve 7 closes, cutting off the communication state between ports A and B of the first hydraulic motor 2. At this time, the hydraulic oil coming out from port B of the first hydraulic motor 2 passes through ports B1 and B2 of the control valve group 3 to port B3 of the second hydraulic motor 4, then comes out from port A3 of the second hydraulic motor 4 to port A2 of the control valve group 3, passes through the internal channel of the control valve group 3 to port A1, and finally reaches port A of the first hydraulic motor 2 through a pipeline, thus completing the cycle of the entire oil circuit. At this time, the energy conversion device is the load of the hydraulic system, and the size of the load determines the pressure of the hydraulic system. At this time, the torque generated by the system pressure difference of the first hydraulic motor 2 acts on the vehicle running wheelset 1 through the connecting device, finally forming a braking force for the vehicle, and the size of the braking force is determined by the pressure of the system. At the same time, the energy conversion device 5 converts the energy of the hydraulic system into other forms of energy for dissipation or storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is one of the structural schematic diagrams of the present invention;

[0022] Figure 2 is another structural schematic diagram of the present invention;

[0023] Figure 3 is still another structural schematic diagram of the present invention;

[0024] Figure 4 is yet another structural schematic diagram of the present invention;

[0025] Wherein, 1. vehicle running wheelset; 2. first hydraulic motor; 3. control valve group; 4. second hydraulic motor; 5. energy conversion device; 6. coupling; 7. communication valve; 8. high-pressure overflow oil replenishing valve group; 9. oil replenishing overflow valve; 10. oil replenishing pump; 11. hydraulic oil tank; 12. axle gearbox; 13. electro-hydraulic proportional first hydraulic motor; 14. check valve; 15. one-way rectifying valve group; 16. electro-hydraulic proportional second hydraulic motor; 17. hydrodynamic retarder; 18. shuttle valve; 19. vehicle prime mover. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] Figure 1In it, hydraulic motor 1-2 and hydraulic motor 2-4 form a closed system. The control valve group 3 is connected in parallel with hydraulic motor 1-2 and hydraulic motor 2-4. Hydraulic motor 1-2 is connected to the vehicle running wheel pair 1, and hydraulic motor 2-4 is connected to the energy conversion device 5. The control valve group 3 includes a communication valve, a two-way overflow valve group for restricting the pressures of the two oil ports A and B on hydraulic motor 1-2. It also includes a makeup oil pump 10 for replenishing oil to the closed system and providing control oil for the communication valve in the control valve group 3, a makeup oil overflow valve 9, and a hydraulic oil tank 11. The pressure of makeup oil pump 10 is limited by makeup oil overflow valve 9. The hydraulic oil tank 11 is used to store hydraulic oil, provide oil suction, and receive return oil.

[0027] The operation mode of the above-mentioned railway vehicle hydraulic braking system is as follows:

[0028] Condition 1: Going downhill on a long and steep slope in the forward direction

[0029] The vehicle moves forward, and the axle gearbox drives hydraulic motor 1-2 to work. Assuming that port A of hydraulic motor 1-2 in the closed system is the oil outlet and port B is the oil inlet at this time. When hydraulic braking is not required to work, the control valve group 3 controls ports A and B of hydraulic motor 2 to be in a communicating state, that is, the oil from port A of hydraulic motor 1-2 directly returns to port B of hydraulic motor 1-2 after passing through the control valve group 3 without driving hydraulic motor 2-4. At this time, the load of the hydraulic system is basically 0, and the system pressure is only the makeup oil pressure of the system. When the vehicle control system issues a signal for hydraulic braking to work, the control valve group 3 acts to cut off the communicating state of ports A and B of hydraulic motor 2-1, that is, the hydraulic oil coming out of port A of hydraulic motor 1-2 returns to port B of hydraulic motor 1-2 after passing through the control valve group 3 and hydraulic motor 2-4. At this time, the energy conversion device 5 is the load of the hydraulic system, and the size of the load determines the pressure of the hydraulic system. At this time, the torque generated by the pressure difference of the closed system on hydraulic motor 1-2 acts on the vehicle running wheel pair 1 through the connecting device to finally form a braking force for the vehicle, and the size of the braking force is determined by the pressure of the system. At the same time, the energy conversion device 5 converts the energy of the hydraulic system into other forms of energy for dissipation or storage. The system refers to the closed system, and the connecting device refers to the axle gearbox.

[0030] Condition 2: Going downhill on a long and steep slope in the reverse direction

[0031] The vehicle moves forward, and the axle gearbox drives the first hydraulic motor 2 to work. Assume that at this time, port B of the first hydraulic motor 2 in the closed system is the oil outlet, and port A is the oil inlet. When hydraulic braking is not required, the control valve group 3 controls ports A and B of the first hydraulic motor 2 to be in a communicating state, that is, the oil from port B of the first hydraulic motor 2 returns directly to port A of the first hydraulic motor 2 after passing through the control valve group 3 without driving the second hydraulic motor 4. At this time, the load of the hydraulic system is basically 0, and the system pressure is only the system make-up oil pressure. When the vehicle control system sends a signal for hydraulic braking to work, the control valve group 3 acts to cut off the communicating state between ports A and B of the first hydraulic motor 2, that is, the hydraulic oil coming out of port B of the first hydraulic motor 2 returns to port A of the first hydraulic motor 2 after passing through the control valve group 3 and the second hydraulic motor 4. At this time, the energy conversion device 5 is the load of the hydraulic system, and the magnitude of the load determines the pressure of the hydraulic system. At this time, the torque generated by the system pressure difference of the first hydraulic motor 2 acts on the vehicle running wheelset 1 through the connecting device and finally forms a braking force for the vehicle. The magnitude of the braking force is determined by the pressure of the system. At the same time, the energy conversion device converts the energy of the hydraulic system into other forms of energy for dissipation or storage. The system refers to the closed system, and the connecting device refers to the axle gearbox.

[0032] Figure 2 In it, the first hydraulic motor 2 is connected to the vehicle running wheelset 1 through the axle gearbox 12, and the axle gearbox 12 has the function of disengaging and engaging gears. The first hydraulic motor 2 can rotate clockwise or counterclockwise following the vehicle running wheelset 1; both the first hydraulic motor 2 and the second hydraulic motor 4 can adjust the motor displacement during operation to meet the system requirements; the energy conversion device 5 can convert the system hydraulic energy into other forms of energy for storage or dissipation; when the first hydraulic motor 2 can rotate clockwise or counterclockwise following the axle, the control valve group 3 can control it; the high-pressure make-up oil overflow valve 8 can limit the system pressure, and the communication valve 7 can control the communication and cut-off of the two main oil circuits of the first hydraulic motor 2; the action of the communication valve 7 is controlled by the electromagnet DT1 on the valve; the oil ports A1, A2, A5, A6 inside the control valve group 3 are internally communicated, and the oil ports B1, B2, B5, A4 are internally communicated.

[0033] The first hydraulic motor 2 is connected to the vehicle running wheelset 1 through the axle gearbox 12. The A port of the first hydraulic motor 2 is connected to the A1 port of the control valve group 3, and the B port of the first hydraulic motor 2 is connected to the B1 port of the control valve group 3. The A2 port of the control valve group 3 is connected to the A3 port of the second hydraulic motor 4, and the B2 port of the control valve group 3 is connected to the B3 port of the second hydraulic motor 4. The energy conversion device 5 is connected to the second hydraulic motor 4 through the coupling 6. The two-way overflow valve group of the control valve group 3 includes two high-pressure overflow oil replenishing valves 8. The A6 port of one high-pressure overflow oil replenishing valve 8 is connected to the A1 port of the control valve group 3, and the A4 port of the other high-pressure overflow oil replenishing valve 8 is connected to the B1 port of the control valve group 3. The B6 port of one high-pressure overflow oil replenishing valve 8, the B4 port of the other high-pressure overflow oil replenishing valve 8 and the P port of the communication valve 7 are connected. The A5 port of the communication valve 7 is connected to the A2 port of the control valve group 3, and the B5 port of the communication valve 7 is connected to the B2 port of the control valve group 3. The oil replenishing pump 10 is connected to the tail of the first hydraulic motor 2. The inlet of the oil replenishing pump 10 is connected to the oil suction port of the hydraulic oil tank 11, and the outlet of the oil replenishing pump 10 is connected to the P1 port of the oil replenishing overflow valve 9, the oil return ports B4 and B6 of the high-pressure oil replenishing overflow valve 8 and the P port of the communication valve 7. The T1 port of the oil replenishing overflow valve 9 and the T port of the communication valve 7 are both connected to the hydraulic oil tank 11. The hydraulic oil tank 11 is used to store hydraulic oil, provide oil suction and receive oil return.

[0034] The oil replenishing pump 10 is connected to the tail of the first hydraulic motor 2 (as Figure 2 ), or the oil replenishing pump 10 is connected to the vehicle prime mover 19 (as Figure 3 ).

[0035] Figure 4In a railway vehicle hydraulic braking system, it includes an electro-hydraulic proportional motor 13, a make-up oil pump 10, a control valve group 3, a one-way rectifier valve group 15, an electro-hydraulic proportional motor 16 and a hydrodynamic retarder 17; the electro-hydraulic proportional motor 13 is connected to the vehicle running wheelset 1 through an axle gearbox 12, and the make-up oil pump 10 is connected to the tail of the electro-hydraulic proportional motor 13; the control valve group 3 includes two high-pressure overflow make-up oil valves 8, a communication valve 7 and a shuttle valve 18; the A port of the electro-hydraulic proportional motor 13 is connected to the A1 port of the control valve group 3, the A2 of the control valve group 3 is connected to the A7 port of the one-way rectifier valve group 15, and the A8 port of the one-way rectifier valve group 15 is connected to the A3 port of the electro-hydraulic proportional motor 16; the B port of the electro-hydraulic proportional motor 13 is connected to the B1 port of the control valve group 3, the B2 port of the control valve group 3 is connected to the B7 port of the one-way rectifier valve group 15, and the B8 port of the one-way rectifier valve group 15 is connected to the B3 port of the electro-hydraulic proportional motor 16; the oil outlet of the make-up oil pump 10 is connected to the P1 port of the make-up oil overflow valve, the P1 port of the make-up oil overflow valve 9 is simultaneously connected to the B4 and B6 ports of the two high-pressure overflow make-up oil valves 8 and the S1 port of the shuttle valve 18, the S2 port of the shuttle valve 18 is connected to the P2 port of the one-way rectifier valve group, and the S port of the shuttle valve 18 is connected to the P port of the communication valve 7; the hydrodynamic retarder 17 is connected to the electro-hydraulic proportional motor 16 through a coupling 6; the inlet of the make-up oil pump 10 is connected to the oil suction port of the hydraulic oil tank 11, and the T1 port of the make-up oil overflow valve, the T port of the communication valve 7, the oil drain port of the electro-hydraulic proportional motor 13, and the oil drain port of the electro-hydraulic proportional motor 16 are all connected to the hydraulic oil tank 11.

[0036] Preferably, the electro-hydraulic proportional motor 13 can rotate clockwise or counterclockwise following the axle.

[0037] Preferably, both the electro-hydraulic proportional motor 13 and the electro-hydraulic proportional motor 16 can adjust the motor displacement during operation to meet the system requirements.

[0038] Preferably, the electro-hydraulic proportional motor 13 can convert the kinetic energy of the vehicle into hydraulic energy.

[0039] Preferably, the hydrodynamic retarder 17 can convert the system hydraulic energy into heat energy for dissipation.

[0040] Preferably, when the electro-hydraulic proportional motor 13 can rotate clockwise or counterclockwise following the axle, the control valve group 3 can control the maximum pressure of the system and the communication or disconnection of the main oil circuit.

[0041] Preferably, the displacement of the electro-hydraulic proportional motor 13 is controlled by the proportional electro-magnet BT1 carried by the motor, and the displacement of the electro-hydraulic proportional motor 16 is controlled by the proportional electro-magnet BT2 carried by itself.

[0042] Preferably, the oil ports A1, A2, A5, and A6 inside the control valve group 3 communicate with each other internally, and the oil ports B1, B2, B5, and A4 communicate with each other internally.

[0043] Preferably, the opening and closing states of the communication valve 7 are controlled by the electro-magnet DT1. When DT1 loses power, the communication valve 7 is in the open state, and when DT1 is powered on, the communication valve 7 is in the closed state.

[0044] Preferably, the opening and closing states of the communication valve 7 respectively control the communication and cut-off of the two main oil circuits.

[0045] Preferably, the high-pressure overflow oil replenishing valve 8 can limit the maximum pressure of the two oil ports of the motor.

[0046] Preferably, the oil replenishing pump 10 is connected to the vehicle running wheel pair 1, and the oil replenishing pump 10 can rotate forward and backward following the vehicle running wheel pair 1. The oil replenishing pump 10 can rotate forward and backward following the vehicle running wheel pair 1 to replenish oil to the closed system and provide control oil to the cut-off valve 7, and the pressure of the oil replenishing pump 10 is limited by the oil replenishing overflow valve 9.

[0047] Preferably, the function of the one-way rectifying valve group 15 is that no matter whether the A1 port of the control valve group 3 is at high pressure and the B1 port is at low pressure or the A1 port is at low pressure and the B1 port is at high pressure, the one-way rectifying valve group 15 will make the A8 port at high pressure and the B8 port at low pressure.

[0048] The operation mode of the above-mentioned railway vehicle hydraulic braking system is as follows:

[0049] Condition 1: Going downhill on a long and steep slope in the forward direction

[0050] The vehicle moves forward, and the axle gearbox 12 drives the first electro-hydraulic motor 13 to work. Assume that at this time, port A of the first electro-hydraulic motor 13 in the closed system is the oil outlet, and port B is the oil inlet. When hydraulic braking is not required, BT1 makes the displacement of the first electro-hydraulic motor 13 in the small displacement state, DT1 of the communication valve 7 loses power, and the communication valve 7 is in the open state, so as to control ports A and B of the first electro-hydraulic motor 13 to be in a communicating state, that is, the oil from port A of the first electro-hydraulic motor 13 directly returns to port B of the first electro-hydraulic motor 13 after passing through ports A5 and B5 of the communication valve 7 on the control valve group 3, without driving the second electro-hydraulic motor 16. At this time, the load of the hydraulic system is basically 0, and the system pressure is only the system make-up oil pressure. When the vehicle control system sends a signal for hydraulic braking work, the proportional solenoid BT1 makes the displacement of the first electro-hydraulic motor 13 in the maximum displacement state. When DT1 of the communication valve 7 is powered on, the communication valve 7 is in the closed state, so as to cut off the communication state between ports A and B of the first electro-hydraulic motor 13, that is, the hydraulic oil coming out of port A of the first electro-hydraulic motor 13 reaches ports A7 and A8 of the one-way rectifier valve group 15 after passing through ports A1 and A2 of the control valve group 3, until port A3 of the second electro-hydraulic motor 16, then returns from port B3 of the second electro-hydraulic motor 16 to ports B8 and B7 of the one-way rectifier valve group 15, passes through ports B2 and B1 of the control valve group 3, and finally reaches port B of the first electro-hydraulic motor 13. At this time, the hydraulic retarder 17 is the load of the hydraulic system, and the size of the load determines the pressure of the hydraulic system. At this time, the torque generated by the pressure difference of the closed system (abbreviation: system) of the first electro-hydraulic motor 13 acts on the vehicle running wheel pair 1 through the axle gearbox 12 and finally forms a braking force of the vehicle. The size of the braking force is determined by the pressure of the system. When adjusting the displacement of the second electro-hydraulic motor 16 through the proportional solenoid BT2, the rotational speed of the second electro-hydraulic motor 16 will change, and thus the rotational speed of the hydraulic retarder 17 will change synchronously. According to the characteristic that the output torque of the hydraulic retarder 17 will change accordingly at different rotational speeds, the load of the second electro-hydraulic motor 16 will change synchronously. The pressure of the system is determined by the displacement and load of the second electro-hydraulic motor 16 at the same time. Therefore, adjusting the displacement of the second electro-hydraulic motor 16 can adjust the pressure of the system, and thus adjust the braking force output by the entire system.

[0051] Condition 2: Going down a long and steep slope in the reverse direction:

[0052] The vehicle moves backward, and the axle gearbox 12 drives the first electro-hydraulic motor 13 to work. Assume that at this time, port B of the first electro-hydraulic motor 13 in the closed system is the oil outlet, and port A is the oil inlet. When hydraulic braking is not required, BT1 makes the displacement of the first electro-hydraulic motor 13 in the small displacement state, DT1 of the communication valve 7 loses power, and the communication valve 7 is in the open state, so as to control ports A and B of the electro-hydraulic motor 13 to be in a communicating state, that is, the oil from port B of the first electro-hydraulic motor 13 directly returns to port A of the electro-hydraulic motor 13 after passing through ports A5 and B5 of the communication valve 7, without driving the electro-hydraulic motor 16. At this time, the load of the hydraulic system is basically 0, and the system pressure is only the system make-up oil pressure. When the vehicle control system sends a signal for hydraulic braking work, the proportional electromagnet BT1 makes the displacement of the first electro-hydraulic motor 13 in the maximum displacement state, DT1 on the communication valve 7 is powered on to make the communication valve 7 in the closed state, so as to cut off the communication state between ports A and B of the first electro-hydraulic motor 13, that is, the hydraulic oil coming out of port B of the first electro-hydraulic motor 13 reaches ports B7 and A8 of the one-way rectifier valve group 15 through ports B1 and B2 of the control valve group 3 until port A3 of the electro-hydraulic motor 16, then returns from port B3 of the electro-hydraulic motor 16 to ports B8 and A7 of the one-way rectifier valve group 15, passes through ports A2 and A1 of the control valve group 3, and finally reaches port A of the first electro-hydraulic motor 13. At this time, the retarder is the load of the hydraulic system, and the size of the load determines the pressure of the hydraulic system. At this time, the torque generated by the system pressure difference of the electro-hydraulic motor 13 acts on the vehicle running wheel pair 1 through the connecting device to finally form a braking force of the vehicle, and the size of the braking force is determined by the pressure of the system. When adjusting the displacement of the second electro-hydraulic motor 16 through the proportional electromagnet BT2, the rotational speed of the second electro-hydraulic motor 16 will change, so the rotational speed of the hydrodynamic retarder 11 will change synchronously. According to the characteristic that the output torque of the hydrodynamic retarder 17 will change accordingly at different rotational speeds, the load of the second electro-hydraulic motor 16 will change synchronously. The pressure of the system is determined by the displacement and load of the second electro-hydraulic motor 16 at the same time. Therefore, adjusting the displacement of the second electro-hydraulic motor 16 can adjust the pressure of the system, so as to adjust the braking force output by the whole system.

Claims

1. A hydraulic braking system for railway vehicles, characterized in that: It includes an electro-hydraulic proportional motor 1, a make-up oil pump, a control valve group, a one-way rectifier valve group, an electro-hydraulic proportional motor 2, and a hydrodynamic retarder; the electro-hydraulic proportional motor 1 is connected to the vehicle running wheels through an axle gearbox, and the make-up oil pump is connected to the tail of the electro-hydraulic proportional motor 1; the control valve group includes two high-pressure overflow make-up oil valves, a communication valve, and a shuttle valve; the A port of the electro-hydraulic proportional motor 1 is connected to the A1 port of the control valve group, the A2 port of the control valve group is connected to both the A7 port of the one-way rectifier valve group and the A1 port of the control valve group, and the A8 port of the one-way rectifier valve group is connected to the A3 port of the electro-hydraulic proportional motor 2; the B port of the electro-hydraulic proportional motor 1 is connected to the B1 port of the control valve group, the B2 port of the control valve group is connected to both the B7 port of the one-way rectifier valve group and the B1 port of the control valve group, and the B8 port of the one-way rectifier valve group is connected to the B3 port of the electro-hydraulic proportional motor 2; the outlet of the make-up oil pump is connected to the P1 port of the make-up oil overflow valve. Both of the two high-pressure overflow make-up oil valves include a one-way valve and a high-pressure overflow valve. The P1 port of the make-up oil overflow valve is simultaneously connected to the inlets of the one-way valves of the two high-pressure overflow make-up oil valves, the outlets of the high-pressure overflow valves of the two high-pressure overflow make-up oil valves, and the S1 inlet of the shuttle valve. The S2 inlet of the shuttle valve is connected to the P2 port of the one-way rectifier valve group, and the S outlet of the shuttle valve is connected to the P port of the communication valve; the hydrodynamic retarder is connected to the electro-hydraulic proportional motor 2 through a coupling; the inlet of the make-up oil pump is connected to the oil suction port of the hydraulic oil tank, and the T1 port of the make-up oil overflow valve, the T port of the communication valve, the oil drain port of the electro-hydraulic proportional motor 1, and the oil drain port of the electro-hydraulic proportional motor 2 are all connected to the hydraulic oil tank; the outlet of the one-way valve of one of the high-pressure overflow make-up oil valves and the inlet of the high-pressure overflow valve of one of the high-pressure overflow make-up oil valves are connected to the A1 port of the control valve group, and the outlet of the one-way valve of the other high-pressure overflow make-up oil valve and the inlet of the high-pressure overflow valve of the other high-pressure overflow make-up oil valve are connected to the B1 port of the control valve group;The one-way rectifying valve group includes four one-way valves. The A7 port of the one-way rectifying valve group is the inlet of the first one-way valve, and the A8 port of the one-way rectifying valve group is the outlet of the first one-way valve. The B7 port of the one-way rectifying valve group is the inlet of the second one-way valve, and the P2 port of the one-way rectifying valve group is the outlet of the second one-way valve. The outlet of the first one-way valve is communicated with the outlet of the second one-way valve. The outlet of the third one-way valve of the one-way rectifying valve group is connected to the A7 port of the one-way rectifying valve group, and the outlet of the fourth one-way valve of the one-way rectifying valve group is connected to the B7 port of the one-way rectifying valve group. The inlets of the third one-way valve and the fourth one-way valve are connected and both are connected to the B8 port of the one-way rectifying valve group. The communication valve includes a cartridge valve and a two-position four-way pilot solenoid valve. The P port of the communication valve is connected to the inlet of the pilot solenoid valve. The oil return port of the pilot solenoid valve is connected to the T port of the communication valve. One working oil port of the pilot solenoid valve is connected to the control port of the cartridge valve, and the other working oil port of the pilot solenoid valve is blocked. One working oil port of the cartridge valve is connected to the A2 port of the control valve group, and the other working oil port of the cartridge valve is connected to the B2 port of the control valve group. When hydraulic braking is not required to work, the displacement of the first electro-hydraulic motor is in the small displacement state, the pilot solenoid valve is de-energized, the two working oil ports of the communication valve are communicated, and the A port and the B port of the first electro-hydraulic motor are communicated.;

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