Locomotive brake control system and control method with fire-free return function

Abstract

This application relates to a locomotive braking control system with a fireless return function, comprising: a main air supply; a train pipe; an emergency booster valve; the inlet of which is connected to the main air supply, and the outlet of which is connected to the inlet of a first mechanical valve and the first inlet of a first two-way valve respectively; a mechanical three-way valve configured to use the pressure of the train pipe to charge air to a working air cylinder; when the pressure of the train pipe drops, the pressure of the working air cylinder can be connected to the actuating air cylinder to control the actuating air cylinder to generate a second pre-control pressure P2; a first two-way valve configured to take the larger of its first and second inlets and output the larger pressure to the second inlet of the second mechanical valve; a first double-control plug valve; a second double-control plug valve; a switching valve configured to switch between its first and second inlets to output P6 to the first inlet of the second two-way valve; a second two-way valve configured to take the larger of its first and second inlets and output the larger pressure to the control port of a relay valve; and a relay valve configured to amplify the flow rate at the inlet of the relay valve and output braking pressure PB to the brake cylinder for braking.

Description

Technical Field

[0001] This application belongs to the field of locomotive braking control, and in particular relates to a locomotive braking control system and control method with a fireless return function. Background Technology

[0002] The locomotive braking control system is one of the most important core systems of a locomotive. One of its key functions is to control the brake cylinder pressure during fireless return trips. The conventional approach for fireless return trips is to use a mechanical distribution valve, independent of the conventional braking system, to respond to the train pipe pressure and output a pre-controlled pressure for the brake cylinders. This pre-controlled pressure is then output through a relay valve to match the pre-controlled pressure.

[0003] In existing locomotive braking control systems, during off-line return trips, a high-flow-rate pressure supply to the relay valve requires the crew to operate a stopcock to introduce train pipe pressure into the relay valve. Additionally, because pressure remains in the averaging pipe after power is cut off, the crew must disembark to open the averaging pipe angle stopcock to release this pressure, thus alleviating brake pressure. These procedures significantly increase the operational difficulty for the crew and necessitate numerous additional accessories to the braking system, increasing its complexity and failure rate. The braking system is a core system for rail transit safety; improving system reliability and reducing operational difficulty are crucial design considerations. Summary of the Invention

[0004] In view of some shortcomings in the related technologies, this application provides a locomotive braking control system and control method with fireless return function.

[0005] The locomotive braking control system (hereinafter referred to as the control system) with fireless return function provided in the first aspect of this application includes:

[0006] The main air supply, after passing through the first check valve, is connected to the brake cylinder and the emergency booster valve respectively. The main air supply is configured to: be able to charge the brake cylinder in one direction, be able to output the first pre-control pressure P1 through the emergency booster valve, and allow the pressure of the brake cylinder to reach the emergency booster valve without flowing back to the main air supply.

[0007] Train pipe; its control port is connected to the emergency booster valve, which can provide control pressure; its air inlet is connected to the mechanical three-way valve, which can charge the mechanical three-way valve; and its first port is connected to the third mechanical valve of the second double-control valve, which can charge the brake cylinder.

[0008] The emergency booster valve has an inlet connected to the main air supply and an outlet connected to the inlet of the first mechanical valve of the first double-controlled plug valve and the first inlet of the first bidirectional valve, respectively, and can output a first pre-controlled pressure P1; the emergency booster valve also has a control port connected to the train pipe, which can control the opening or closing of the emergency booster valve.

[0009] The mechanical three-way valve has an air inlet connected to the train pipe and is connected to the working air cylinder and the actuating air cylinder respectively. The mechanical three-way valve is configured to: use the pressure of the train pipe to charge air to the working air cylinder; when the pressure of the train pipe drops, the pressure of the working air cylinder can be connected to the actuating air cylinder to control the actuating air cylinder to generate a second pre-control pressure P2; the second pre-control pressure P2 can reach the second inlet of the first two-way valve and the first inlet of the second mechanical valve of the first double-control plug valve respectively.

[0010] The first two-way valve is configured to take the larger of its first and second inlets and output the third pre-control pressure P3 to the second inlet of the second mechanical valve of the first two-way control valve.

[0011] The first dual-control valve has a first mechanical valve and a second mechanical valve that can be linked together. The first mechanical valve has an inlet and an outlet, and the second mechanical valve has an outlet and a first inlet and a second inlet that can be switched. The first dual-control valve is configured such that: in the non-flame-free return state, the inlet and outlet of the first mechanical valve are connected to output a first pre-control pressure P1, and the first inlet of the second mechanical valve is connected to its outlet to output a second pre-control pressure P2 as a fourth pre-control pressure P4; in the flame-free return state, the first mechanical valve is shut off, and the second inlet of the second mechanical valve is connected to its outlet to output a third pre-control pressure P3 as the fourth pre-control pressure P4.

[0012] The second dual-control valve has at least a third mechanical valve; the first port of the third mechanical valve is connected to the train pipe, and the second port is connected to the brake cylinder; the second dual-control valve is configured such that: in the non-flame-free return state, the first and second ports of the third mechanical valve are cut off; in the flame-free return state, the first and second ports of the third mechanical valve are connected, enabling air to be supplied to the brake cylinder through the train pipe;

[0013] The second check valve is located between the train pipe and the brake cylinder and is configured to allow one-way airflow from the train pipe to the brake cylinder and not allow reverse airflow.

[0014] A switching valve; the first inlet of the switching valve is connected to the outlet of the second mechanical valve of the first double-controlled plug valve, and can input a fourth pre-control pressure P4; the second inlet of the switching valve is connected to a fifth pre-control pressure P5; the outlet of the switching valve is connected to the first inlet of the second bidirectional valve; the switching valve is configured to be able to switch between its first inlet and second inlet to output one of the fourth pre-control pressure P4 and the fifth pre-control pressure P5 as a sixth pre-control pressure P6 to the first inlet of the second bidirectional valve;

[0015] The second two-way valve; the first inlet of the second two-way valve is connected to the outlet of the switching valve, and the second inlet of the second two-way valve is connected to the outlet of the first mechanical valve; the outlet of the second two-way valve is connected to the control port of the relay valve; the second two-way valve is configured to: select the larger pressure between its first inlet and second inlet as the eighth pre-control pressure P8 to be output to the control port of the relay valve; and,

[0016] The relay valve; the inlet of the relay valve is connected to the main air supply and the brake cylinder, and its outlet is connected to the brake cylinder; the relay valve is configured to amplify the flow rate at the inlet of the relay valve according to the eighth pre-control pressure P8 at the control port of the relay valve, so as to output the brake pressure PB to the brake cylinder.

[0017] In one embodiment, the control system further includes an average pipe capable of outputting average pipe pressure PA and a third two-way valve; the second dual-control plug valve also has a fourth mechanical valve capable of being linked with the third mechanical valve; the port of the fourth mechanical valve is capable of switching between shut-off and open to the atmosphere;

[0018] The outlet of the first mechanical valve is connected to the first inlet of the third two-way valve (instead of connecting to the second inlet of the second two-way valve mentioned above), and is able to output the first pre-control pressure P1; the averaging pipe is connected to the second inlet of the third two-way valve and the port of the fourth mechanical valve respectively;

[0019] The outlet of the third bidirectional valve is connected to the second inlet of the second bidirectional valve; the third bidirectional valve is configured to select the larger pressure between its first inlet and second inlet as the seventh pre-control pressure P7 and output it to the second inlet of the second bidirectional valve.

[0020] The second dual-control valve is configured such that, in the non-flame-free return state, the first and second ports of the third mechanical valve are shut off, and the port of the fourth mechanical valve is shut off; in the flame-free return state, the first and second ports of the third mechanical valve are connected, enabling unidirectional air supply to the brake cylinder through the train pipe, and the fourth mechanical valve is connected to the atmosphere, enabling the discharge of the average pipe pressure PA.

[0021] In one embodiment, a second pressure reducing valve is provided between the outlet of the first bidirectional valve and the second inlet of the second mechanical valve to adjust the pressure entering the second inlet of the second mechanical valve.

[0022] In one embodiment, a third check valve connected in parallel with the second pressure reducing valve is provided between the outlet of the first two-way valve and the second inlet of the second mechanical valve. This check valve allows pressure to flow from the second inlet of the second mechanical valve to the outlet of the first two-way valve, but does not allow reverse flow.

[0023] In one embodiment, the switching valve has a control port; the inlet of the electrically controlled valve is connected to the main air supply, and the outlet of the electrically controlled valve is connected to the control port of the switching valve; the electrically controlled valve is configured to: when energized, connect the main air supply and the control port of the switching valve, so that the second inlet of the switching valve is connected, and output a fifth pre-control pressure P5 as a sixth pre-control pressure P6; when de-energized, disconnect the main air supply and the control port of the switching valve, switch the switching valve to the first inlet connection, and output a fourth pre-control pressure P4 as a sixth pre-control pressure P6.

[0024] In one embodiment, a first pressure reducing valve is provided between the first check valve and the emergency pressure boosting valve to adjust the pressure entering the emergency pressure boosting valve.

[0025] In one embodiment, the second check valve is located between the second port of the third mechanical valve and the brake cylinder.

[0026] In one embodiment, the fifth pre-controlled pressure P5 comes from the main air supply and is obtained by the charging and discharging solenoid valve through charging and discharging.

[0027] The locomotive braking control method with fireless return function (hereinafter referred to as the control method) provided in the second aspect of this application adopts the control system described in any of the preceding embodiments, and the control method includes at least one of the following modes:

[0028] Normal working mode:

[0029] In normal operating mode, both the first and second dual-control valves are in a non-flame-free return state; at this time, the inlet and outlet of the first mechanical valve are connected, the first inlet and outlet of the second mechanical valve are connected, and the third mechanical valve is shut off.

[0030] The main air supply reaches the brake cylinder through the first check valve to charge it; when the locomotive needs to brake, the brake cylinder supplies air to the relay valve; the main air supply also reaches the inlet of the emergency booster valve through the first check valve.

[0031] At this time, the second inlet and outlet of the switching valve are connected, and the fifth pre-control pressure P5 can be output as the sixth pre-control pressure P6 to the first inlet of the second bidirectional valve.

[0032] When the locomotive is released, the train pipe is purged to a constant pressure and the emergency booster valve is closed; at this time, the fifth pre-control pressure P5 is reduced, the pressure at the control port of the relay valve is released, and the brake cylinder pressure PB is not output.

[0033] When the locomotive is under normal braking, the fifth pre-control pressure P5 is increased and passes through the switching valve to become the sixth pre-control pressure P6, which reaches the first inlet of the second two-way valve. The second two-way valve takes the larger value and outputs the eighth pre-control pressure P8, which reaches the control port of the relay valve. The relay valve outputs the required brake cylinder pressure PB through flow amplification to brake. At this time, the train pipe pressure drops from the constant pressure to the normal braking pressure, the emergency booster valve remains closed, and the first pre-control pressure P1 is not output to the second inlet of the second two-way valve.

[0034] When the locomotive brakes suddenly, the pressure in the train pipe is rapidly released, the emergency booster valve opens, and the main air sequentially passes through the first check valve, the emergency booster valve, and the first mechanical valve to output the first pre-control pressure P1 to the second inlet of the second two-way valve; the fifth pre-control pressure P5 is still output through the switching valve as the sixth pre-control pressure P6 to the first inlet of the second two-way valve; the second two-way valve takes the larger of the first pre-control pressure P1 and the sixth pre-control pressure P6 and outputs the eighth pre-control pressure P8 to the control port of the relay valve, which then outputs the required brake cylinder pressure PB for braking.

[0035] Fifth Pre-Controlled Pressure Failure Mode

[0036] In the fifth pre-control pressure P5 failure mode, both the first and second dual-control valves are in a non-flame-free return state; at this time, the inlet and outlet of the first mechanical valve are connected, the first inlet and outlet of the second mechanical valve are connected, and the third mechanical valve is shut off.

[0037] The main air supply reaches the brake cylinder through the first check valve to charge it; when the locomotive needs to brake, the brake cylinder supplies air to the relay valve; the main air supply also reaches the inlet of the emergency booster valve through the first check valve.

[0038] At this time, since the fifth pre-control pressure P5 fails, the switching valve switches to the first inlet and outlet connection, and can output the fourth pre-control pressure P4 as the sixth pre-control pressure P6 to the first inlet of the second two-way valve.

[0039] When the locomotive is released, the train pipe is filled with air to a constant pressure, and the working air cylinder is filled to a constant pressure through the mechanical three-way valve; the mechanical three-way valve does not output pressure to the working air cylinder; the pressure at the control port of the relay valve is discharged and the brake cylinder pressure PB is not output.

[0040] When the locomotive is under normal braking, the pressure in the train pipe drops from the constant pressure to the normal braking pressure. The mechanical three-way valve activates, outputting the pressure from the working air cylinder to the actuating air cylinder, generating a second pre-control pressure P2. This second pre-control pressure P2 reaches the first inlet of the second mechanical valve and is output as the fourth pre-control pressure P4 to the first inlet of the switching valve. The sixth pre-control pressure P6 is then output from the switching valve to the first inlet of the second bidirectional valve. The second bidirectional valve takes the larger value and outputs the eighth pre-control pressure P8 to the control port of the relay valve. The relay valve outputs the required brake cylinder pressure PB for braking. At this time, the train pipe pressure drops from the constant pressure to the normal braking pressure, and the emergency booster valve remains closed, not outputting the first pre-control pressure P1 to the second inlet of the second bidirectional valve.

[0041] When the locomotive brakes suddenly, the pressure in the train pipe is rapidly released, the emergency booster valve opens, and the main air flows sequentially through the first check valve, the emergency booster valve, and the first mechanical valve to output the first pre-control pressure P1 to the second inlet of the second two-way valve. The second pre-control pressure P2 from the mechanical three-way valve is still input through the first inlet of the second mechanical valve and outputs the fourth pre-control pressure P4. Through the switching valve, the sixth pre-control pressure P6 is formed and reaches the first inlet of the second two-way valve. The second two-way valve takes the larger of the first pre-control pressure P1 and the sixth pre-control pressure P6 and outputs the eighth pre-control pressure P8 to the control port of the relay valve. The relay valve outputs the required brake cylinder pressure PB through flow amplification to brake.

[0042] Fireless return mode

[0043] In the flameless return mode, both the first and second dual-control plugs switch from the non-flameless return state to the flameless return state; at this time, the first mechanical valve is shut off, the second inlet and outlet of the second mechanical valve are connected; the first port and the second port of the third mechanical valve are connected, and the port of the fourth mechanical valve is connected to the atmosphere.

[0044] At this time, the pressure of the main air is lost, and an external air source is used to fill the train pipe with air to a constant pressure so as to supply air to the control system; the pressure of the train pipe passes through the third mechanical valve and the second check valve to fill the brake cylinder with constant pressure; when the locomotive needs to brake, the brake cylinder supplies air to the relay valve and the emergency booster valve respectively, and the first check valve and the second check valve prevent the brake cylinder from supplying air to the main air and the train pipe in reverse.

[0045] At this time, the first inlet and outlet of the switching valve are connected, and the fourth pre-control pressure P4 can be output as the sixth pre-control pressure P6 to the first inlet of the second two-way valve.

[0046] When the locomotive is released, the train pipe is filled with air to a constant pressure through an external air source, and then the working air cylinder is filled to a constant pressure through a mechanical three-way valve; the mechanical three-way valve does not output pressure to the working air cylinder; the pressure at the control port of the relay valve is discharged and the brake cylinder pressure PB is not output.

[0047] When the locomotive is under normal braking, the pressure in the train pipe drops from the constant pressure to the service braking pressure. The mechanical three-way valve activates, outputting the pressure from the working air cylinder to the actuating air cylinder, generating a second pre-control pressure P2, which is output to the second inlet of the first two-way valve. After being maximized by the first two-way valve, a third pre-control pressure P3 is output to the second inlet of the second mechanical valve, which serves as the fourth pre-control pressure P4, output to the first inlet of the switching valve. A sixth pre-control pressure P6 is also output from the switching valve to the first inlet of the second two-way valve. After being maximized by the second two-way valve, an eighth pre-control pressure P8 is output to the control port of the relay valve. The relay valve then outputs the required brake cylinder pressure PB for braking. At this time, the pressure in the train pipe is the service braking pressure, the emergency booster valve remains closed, and the first pre-control pressure P1 is not output to the first inlet of the first two-way valve. The first mechanical valve is shut off, and there is no input to the second inlet of the second two-way valve.

[0048] When the locomotive brakes suddenly, the pressure in the train pipe is rapidly released, and the emergency booster valve opens. Due to the reverse cutoff of the first and second check valves, the pressure in the brake cylinder is output as the first pre-control pressure P1 via the emergency booster valve, reaching the first inlet of the first two-way valve. The second pre-control pressure P2 from the mechanical three-way valve also reaches the first inlet of the first two-way valve. The first two-way valve takes the larger of the first and second pre-control pressures P1 and outputs the third pre-control pressure P3, which reaches the second inlet of the second mechanical valve. This third pre-control pressure P4 is then output to the first inlet of the switching valve, and the sixth pre-control pressure P6 is output from the switching valve to the first inlet of the second two-way valve. The second two-way valve takes the larger of the pre-control pressures P8, which is then output to the control port of the relay valve. The relay valve amplifies the flow and outputs the required brake cylinder pressure PB for braking. At this time, due to the cutoff of the first mechanical valve, the second inlet of the second two-way valve still has no input.

[0049] In one embodiment, more specifically, the control method includes at least one of the following modes:

[0050] Normal working mode

[0051] In normal operating mode, both the first and second dual-control valves are in a non-flame-free return state; at this time, the inlet and outlet of the first mechanical valve are connected, the first inlet and outlet of the second mechanical valve are connected, the third mechanical valve is shut off, and the port of the fourth mechanical valve is shut off.

[0052] The main air supply reaches the brake cylinder through the first check valve to charge it; when the locomotive needs to brake, the brake cylinder supplies air to the relay valve; the main air supply also reaches the inlet of the emergency booster valve through the first check valve.

[0053] At this time, the second inlet and outlet of the switching valve are connected, and the fifth pre-control pressure P5 can be output as the sixth pre-control pressure P6 to the first inlet of the second bidirectional valve.

[0054] When the locomotive is released, the train pipe is purged to a constant pressure and the emergency booster valve is closed; at this time, the fifth pre-control pressure P5 is reduced, the pressure at the control port of the relay valve is released, and the brake cylinder pressure PB is not output.

[0055] When the locomotive is under normal braking, the fifth pre-control pressure P5 is increased and passes through the switching valve to become the sixth pre-control pressure P6, reaching the first inlet of the second two-way valve; the average pipe pressure PA reaches the second inlet of the third two-way valve, and the larger of the two pressures is taken to output the seventh pre-control pressure P7 to the second inlet of the second two-way valve; the second two-way valve takes the larger of the sixth pre-control pressure P6 and the seventh pre-control pressure P7, and outputs the eighth pre-control pressure P8 to the control port of the relay valve; the relay valve outputs the required brake cylinder pressure PB through flow amplification to brake; at this time, the train pipe pressure drops from the constant pressure to the normal braking pressure, the emergency booster valve remains closed, and the first pre-control pressure P1 is not output to the first inlet of the third two-way valve;

[0056] When the locomotive brakes suddenly, the pressure in the train pipe is rapidly released, the emergency booster valve opens, and the main air sequentially passes through the first check valve, the emergency booster valve, and the first mechanical valve to output the first pre-control pressure P1 to the first inlet of the third two-way valve; the average pipe pressure PA reaches the second inlet of the third two-way valve; the third two-way valve takes the larger of the first pre-control pressure P1 and the average pipe pressure PA, and outputs the seventh pre-control pressure P7 to the second inlet of the second two-way valve; the fifth pre-control pressure P5 still passes through the switching valve to output the sixth pre-control pressure P6 to the first inlet of the second two-way valve; the second two-way valve takes the larger of the sixth pre-control pressure P6 and the seventh pre-control pressure P7, and outputs the eighth pre-control pressure P8 to the control port of the relay valve, which then outputs the required brake cylinder pressure PB for braking.

[0057] Fifth Pre-Controlled Pressure Failure Mode

[0058] In the fifth pre-controlled pressure P5 failure mode, both the first and second dual-control valves are in a non-flame-free return state; at this time, the inlet and outlet of the first mechanical valve are connected, the first inlet and outlet of the second mechanical valve are connected, the third mechanical valve is cut off, and the port of the fourth mechanical valve is cut off.

[0059] The main air supply reaches the brake cylinder through the first check valve to charge it; when the locomotive needs to brake, the brake cylinder supplies air to the relay valve; the main air supply also reaches the inlet of the emergency booster valve through the first check valve.

[0060] At this time, since the fifth pre-control pressure P5 fails, the switching valve switches to the first inlet and outlet connection, and can output the fourth pre-control pressure P4 as the sixth pre-control pressure P6 to the first inlet of the second two-way valve.

[0061] When the locomotive is released, the train pipe is filled with air to a constant pressure, and the working air cylinder is filled to a constant pressure through the mechanical three-way valve; the mechanical three-way valve does not output pressure to the working air cylinder; the pressure at the control port of the relay valve is discharged and the brake cylinder pressure PB is not output.

[0062] When the locomotive is under normal braking, the pressure in the train pipe drops from the constant pressure to the normal braking pressure. The mechanical three-way valve activates, outputting the pressure from the working air cylinder to the actuating air cylinder, generating a second pre-control pressure P2. This second pre-control pressure P2 reaches the first inlet of the second mechanical valve and is output as the fourth pre-control pressure P4 to the first inlet of the switching valve. From the switching valve, the sixth pre-control pressure P6 is output to the first inlet of the second bidirectional valve. The average pipe pressure PA reaches the second inlet of the third bidirectional valve, and the larger of the two pressures is taken to output the seventh pre-control pressure P7 to the second inlet of the second bidirectional valve. The second bidirectional valve takes the larger of the sixth and seventh pre-control pressures P6 and outputs the eighth pre-control pressure P8 to the control port of the relay valve. The relay valve then outputs the required brake cylinder pressure PB for braking. At this time, the train pipe pressure drops from the constant pressure to the normal braking pressure, and the emergency booster valve remains closed, not outputting the first pre-control pressure P1 to the first inlet of the third bidirectional valve.

[0063] When the locomotive brakes suddenly, the pressure in the train pipe is rapidly released, the emergency booster valve opens, and the main air sequentially passes through the first check valve, the emergency booster valve, and the first mechanical valve to output the first pre-control pressure P1 to the first inlet of the third two-way valve; the average pipe pressure PA reaches the second inlet of the third two-way valve; the third two-way valve takes the larger of the first pre-control pressure P1 and the average pipe pressure PA, and outputs the seventh pre-control pressure P7 to the second inlet of the second two-way valve; the second pre-control pressure P2 from the mechanical three-way valve is still input through the first inlet of the second mechanical valve and outputs the fourth pre-control pressure P4, which is formed by the switching valve to form the sixth pre-control pressure P6, reaching the first inlet of the second two-way valve; the second two-way valve takes the larger of the sixth pre-control pressure P6 and the seventh pre-control pressure P7, and outputs the eighth pre-control pressure P8 to the control port of the relay valve. The relay valve outputs the required brake cylinder pressure PB through flow amplification to brake.

[0064] Fireless return mode

[0065] In the flameless return mode, both the first and second dual-control plugs switch from the non-flameless return state to the flameless return state; at this time, the first mechanical valve is shut off, the second inlet and outlet of the second mechanical valve are connected; the first port and the second port of the third mechanical valve are connected, and the port of the fourth mechanical valve is connected to the atmosphere.

[0066] At this time, the pressure of the main air is lost, and an external air source is used to fill the train pipe with air to a constant pressure so as to supply air to the control system; the pressure of the train pipe passes through the third mechanical valve and the second check valve to fill the brake cylinder with constant pressure; when the locomotive needs to brake, the brake cylinder supplies air to the relay valve and the emergency booster valve respectively, and the first check valve and the second check valve prevent the brake cylinder from supplying air to the main air and the train pipe in reverse.

[0067] At this time, the first inlet and outlet of the switching valve are connected, and the fourth pre-control pressure P4 can be output as the sixth pre-control pressure P6 to the first inlet of the second two-way valve.

[0068] When the locomotive is released, the train pipe is filled with air to a constant pressure through an external air source; the working air cylinder is filled to a constant pressure through a mechanical three-way valve; the mechanical three-way valve does not output pressure to the working air cylinder; the pressure at the control port of the relay valve is discharged and the brake cylinder pressure PB is not output.

[0069] When the locomotive is under normal braking, the pressure in the train pipe drops from the constant pressure to the normal braking pressure. The mechanical three-way valve activates, outputting the pressure from the working air cylinder to the acting air cylinder, generating a second pre-control pressure P2, which is output to the second inlet of the first two-way valve. After being maximized by the first two-way valve, the third pre-control pressure P3 is output to the second inlet of the second mechanical valve, serving as the fourth pre-control pressure P4, which is output to the first inlet of the switching valve. The sixth pre-control pressure P6 is output from the switching valve to the first inlet of the second two-way valve. After being maximized by the second two-way valve, the eighth pre-control pressure P8 is output to the control port of the relay valve. The relay valve then outputs the required brake cylinder pressure PB for braking. At this time, since the first mechanical valve is shut off and the average pipe pressure PA is emptied by the fourth mechanical valve, the third two-way valve has no output. In addition, the pressure in the train pipe is the normal braking pressure, and the emergency booster valve remains closed, not outputting the first pre-control pressure P1 to the first inlet of the first two-way valve.

[0070] When the locomotive brakes suddenly, the pressure in the train pipe is rapidly released, and the emergency booster valve opens. Due to the reverse cutoff of the first and second check valves, the pressure in the brake cylinder is output as the first pre-control pressure P1 via the emergency booster valve, reaching the first inlet of the first two-way valve. The second pre-control pressure P2 from the mechanical three-way valve also reaches the first inlet of the first two-way valve. The first two-way valve takes the larger of the first and second pre-control pressures P1 and outputs the third pre-control pressure P3, which reaches the second inlet of the second mechanical valve. This third pre-control pressure P4 is then output to the first inlet of the switching valve, and the sixth pre-control pressure P6 is output from the switching valve to the first inlet of the second two-way valve. The second two-way valve takes the larger of the pre-control pressures P8, which is then output to the control port of the relay valve. The relay valve amplifies the flow and outputs the required brake cylinder pressure PB for braking. At this time, the third two-way valve still has no output.

[0071] The control system and method provided in at least one embodiment of this application employ a switching valve to simultaneously achieve the functions of power failure safety guidance and brake cylinder pressure control in the no-fire return mode. Through the safety guidance functions of the mechanical three-way valve and the emergency booster valve, the probability of brake failure is greatly reduced, significantly improving the system's safety.

[0072] The control system and method provided in at least one embodiment of this application allow the crew to switch the locomotive to a fireless return mode without having to get off the train to operate the average pipe gate, or to perform operations such as closing the main air gate or opening the train pipe gate. The crew only needs to rotate the first and second gates to complete the fireless return mode setting, which greatly reduces the difficulty of operation for the crew, reduces the number of inspection points, and reduces the probability of errors. Attached Figure Description

[0073] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0074] Figure 1 This is a schematic diagram of the overall control system;

[0075] Figure 2 A flowchart illustrating the normal operating mode of the control system;

[0076] Figure 3 This is a flowchart illustrating the fifth pre-control pressure failure mode of the control system.

[0077] Figure 4 A flowchart illustrating the fireless return mode of the control system;

[0078] In the diagram: 1 Main air supply, 2 First double-control valve, 21 First mechanical valve, 22 Second mechanical valve, 3 Second double-control valve, 31 Third mechanical valve, 32 Fourth mechanical valve, 41 First check valve, 42 Second check valve, 43 Third check valve, 5 Brake cylinder, 61 First pressure reducing valve, 62 Second pressure reducing valve, 7 Emergency booster valve, 81 First two-way valve, 82 Second two-way valve, 83 Third two-way valve, 9 Train pipe, 10 Mechanical three-way valve, 11 Working cylinder, 12 Actuating cylinder, 13 Switching valve, 14 Electrically controlled valve, 15 Average pipe, 16 Relay valve, 17 Brake cylinder. Detailed Implementation

[0079] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0080] In the description of this application, it should be understood that the terms "center", "lateral", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0081] The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include one or more of that feature.

[0082] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0083] The relay valve in this application has a flow amplification function, providing an air source through its inlet to ensure that the pressure of the gas output from its outlet matches the pressure provided by its control port. The two-way valve in this application has a pressure comparison and selection function, automatically comparing the pressures at the two inlets and selecting the one with the higher pressure for output. The check valve in this application is a one-way valve, allowing only flow from one side to the other and preventing reverse flow. The relay valve, two-way valve, and check valve are all mechanical valves, effectively handling power outages.

[0084] like Figure 1-4 As shown, the first embodiment of this application provides a locomotive braking control system (hereinafter referred to as the control system) with a fireless return function, including: a main air supply 1, a first dual-control valve 2, and a second dual-control valve 3; wherein,

[0085] After passing through the first check valve 41, the main air supply 1 is connected to the brake cylinder 5 and the first pressure reducing valve 61. On one hand, the main air supply 1 is connected to the brake cylinder 5, providing unidirectional air supply and braking pressure. On the other hand, the main air supply 1 passes through the first pressure reducing valve 61 and the emergency booster valve 7, outputting a first pre-control pressure P1. This first pre-control pressure P1 can reach the first inlet of the first two-way valve 81 and the inlet of the first mechanical valve 21 of the first dual-control plug valve 2. Furthermore, in the no-fireback mode, the pressure in the brake cylinder 5 reaches the first pressure reducing valve 61 and will not flow back to the main air supply 1.

[0086] The control port of the emergency booster valve 7 is controlled by pressure from the train pipe 9 to open or close; thereby opening or cutting off the pipeline between the first pressure reducing valve 61 and the first two-way valve 81 and the first mechanical valve 21 to control the output of the first pre-control pressure P1. When the pressure in the train pipe 9 is higher than the operating pressure of the emergency booster valve 7, the emergency booster valve 7 is controlled to be closed; when the pressure in the train pipe 9 drops to the operating pressure, the emergency booster valve 7 is controlled to be open, so that the first pre-control pressure P1 is output.

[0087] In some conventional locomotive braking control systems, the operating pressure of the emergency booster valve 7 is approximately 135 kPa; the constant pressure of the train pipe 9 is 500-600 kPa. During braking, the pressure in the train pipe 9 can be reduced from the constant pressure to the service braking pressure via a balancing air cylinder (not shown in the figure). At this time, the emergency booster valve 7 is in the off state (i.e., both the constant pressure and the service braking pressure of the train pipe 9 are greater than the operating pressure of the emergency booster valve 7). Furthermore, the pressure in the train pipe 9 can be further released, for example, through the balancing air cylinder (approximately 30 seconds) or through a quick pressure relief valve (approximately 3 seconds). For example, during emergency braking, the pressure in the train pipe can be released within 3 seconds using the pressure relief valve to achieve emergency braking; at this time, the emergency booster valve 7 is in the open state. The control of the train pipe pressure and the emergency booster valve are existing technologies and can be understood by referring to existing literature.

[0088] Mechanical three-way valve 10 is a mechanical valve capable of outputting a second pre-controlled pressure P2; a regulating three-way valve is optional. The regulating three-way valve operates by changing the position of the valve core to alter the direction and size of the fluid channel. The valve core's position can be changed manually or automatically. If an increase in flow is required, the valve core moves towards the inlet, making it easier for fluid to flow through the channel. Conversely, if a decrease in flow is required, the valve core moves towards the outlet, covering part of the pipe and reducing the flow. Mechanical three-way valve 10 is also a conventional valve, as described in CN116811819A for further understanding.

[0089] The air inlet of the mechanical three-way valve 10 is connected to the train pipe 9. The mechanical three-way valve 10 is also connected to the working air cylinder 11 and the actuating air cylinder 12. The mechanical three-way valve 10 is configured to use the pressure of the train pipe 9 to charge air into the working air cylinder 11. When the pressure of the train pipe 9 drops, the pressure of the working air cylinder 9 can be connected to the actuating air cylinder 12, controlling the actuating air cylinder 12 to generate a corresponding second pre-control pressure P2. The second pre-control pressure P2 can reach the second inlet of the first two-way valve 81 and the first inlet of the second mechanical valve 22 of the first double-control plug 2.

[0090] The first two-way valve 81 is configured to take the larger of its first inlet and second inlet to select the larger of the first pre-control pressure P1 and the second pre-control pressure P2 and output it as the third pre-control pressure P3 to the second inlet of the second mechanical valve 22 of the first double-control valve 2.

[0091] The first dual-control valve 2 has a first mechanical valve 21 and a second mechanical valve 22 that can be linked; that is, the two mechanical valves of the same dual-control valve can be switched simultaneously. The inlet of the first mechanical valve 21 is connected to the outlet of the emergency booster valve 7, and its outlet is connected to the first inlet of the third two-way valve 83. As mentioned above, the first inlet of the second mechanical valve 22 is connected to the outlet of the mechanical three-way valve 10 and the actuating air cylinder 12, and the second inlet of the second mechanical valve 22 is connected to the outlet of the first two-way valve 81, and can be switched between its first inlet and second inlet; the outlet of the second mechanical valve 22 is connected to the first inlet of the switching valve 13 to output a fourth pre-control pressure P4 (one of the second pre-control pressure P2 and the third pre-control pressure P3) to the first inlet of the switching valve 13.

[0092] Through manual operation, the first dual-control plug valve 2 can switch between a non-flameless return state and a flameless return state (the two mechanical valves switch in tandem). Specifically, in the non-flameless return state, such as... Figure 1-3 As shown, the first mechanical valve 21 is open, connecting the outlet of the emergency booster valve 7 and the first inlet of the third two-way valve 83, to output the first pre-control pressure P1 to the first inlet of the third two-way valve 83; the second mechanical valve 22 connects the first inlet of the mechanical three-way valve 10 and the switching valve 13, to output the second pre-control pressure P2 as the fourth pre-control pressure P4 to the first inlet of the switching valve 13. In the no-flame return state, as... Figure 4 As shown, the first mechanical valve 21 is shut off (specifically, its inlet is shut off and its outlet is switched to be connected to the atmosphere); the second mechanical valve 22 is switched to be connected to the outlet of the first two-way valve 81 and the first inlet of the switching valve 13, so as to output the third pre-control pressure P3 as the fourth pre-control pressure P4 to the first inlet of the switching valve 13.

[0093] In one embodiment, a second pressure-reducing valve 62 and a third check valve 43 are connected in parallel between the outlet of the first two-way valve 81 and the second inlet of the second mechanical valve 22. The second pressure-reducing valve 62 reduces the third pre-control pressure P3 from the first two-way valve 81, resulting in a reduced third pre-control pressure P3' that is input to the second inlet of the second mechanical valve 22. Especially for locomotives without heating, the brake cylinder pressure is generally specified not to exceed a set value, such as 250 kPa; therefore, the second pressure-reducing valve 62 effectively controls the pressure. The third check valve 43 is configured to allow air pressure flow from the second inlet of the second mechanical valve 22 to the outlet of the first two-way valve 81, but not vice versa. This configuration prevents excessive pressure from flowing from the front to the rear via the second pressure-reducing valve 62, while allowing excessive pressure at the rear to flow back to the front for pressure reduction; that is, the pressure can be reduced in reverse via the third check valve, increasing the system's flexibility.

[0094] The second inlet of switching valve 13 is connected to a fifth pre-controlled pressure P5; wherein, the fifth pre-controlled pressure P5 comes from the main air supply 1 and is obtained by charging and venting through the charging and venting solenoid valve (not shown in the figure). For example, the first main air supply, the first solenoid valve and the second solenoid valve in CN111634304A can be used to obtain the fifth pre-controlled pressure P5 by charging and venting. Alternatively, the fifth pre-controlled pressure P5 can be obtained by charging and venting through the main air supply, the first charging solenoid valve and the first venting solenoid valve in CN116811819A.

[0095] The switching valve 13 can switch between its first inlet and second inlet to input a fourth pre-control pressure P4 or a fifth pre-control pressure P5; the outlet of the switching valve 13 is connected to the first inlet of the second two-way valve 82 to output a sixth pre-control pressure P6 (i.e., P6 = P4 or P6 = P5) to the first inlet of the second two-way valve 82.

[0096] The switching valve 13 is a mechanical switching valve with a control port, configured to: connect to the second inlet when there is an air source at its control port, inputting a fifth pre-control pressure P5 as the sixth pre-control pressure P6; and switch to connect to the first inlet when there is no air source at its control port, inputting a fourth pre-control pressure P4 as the sixth pre-control pressure P6. More specifically, the control system also includes an electrically controlled valve 14 for controlling the switching valve 13 to switch between the first and second inlets. The inlet of the electrically controlled valve 14 is connected to the main air supply 1, and its outlet is connected to the control port of the switching valve 13. The electrically controlled valve 14 is configured to: when energized, connect the main air supply 1 and the control port of the switching valve 13, connecting the second inlet of the switching valve 13 and inputting the fifth pre-control pressure P5; and when de-energized, disconnect the main air supply 1 and the control port of the switching valve 13, connecting the first inlet of the switching valve 13 and inputting the fourth pre-control pressure P4. When power is lost, the switching valve 13 will automatically switch to connect to its first inlet and input the fourth pre-control pressure P4 as the sixth pre-control pressure P6 to the first inlet of the second two-way valve 82.

[0097] The control system also has an average pipe 15 capable of outputting average pipe pressure PA; wherein the average pipe 15 is connected to the second inlet of the third two-way valve 83 and the port of the fourth mechanical valve 32 of the second double-control plug valve 3 to output average pipe pressure PA.

[0098] The second dual-control valve 3 has a third mechanical valve 31 and a fourth mechanical valve 32 that can be linked. The first port of the third mechanical valve 31 is connected to the train pipe 9, and its second port is connected to the brake cylinder 5 through the second check valve 42, providing one-way access to the brake cylinder 5. The port of the fourth mechanical valve 32 can switch between shut-off and atmospheric connection.

[0099] The second dual-control valve 3 can be switched between a non-flameless return state and a flameless return state via manual operation (the two mechanical valves switch in tandem). Specifically, in the non-flameless return state, such as... Figure 1-3 As shown, the third mechanical valve 31 is shut off (specifically, its first port is shut off, and its second port is switched to the atmosphere); the fourth mechanical valve 32 is shut off, and the average pipe pressure PA can reach the second inlet of the third two-way valve 83, serving as a redundant design for pre-controlled pressure to enhance system reliability. In the no-flame return state, as... Figure 4 As shown, the third mechanical valve 31 is opened to connect the train pipe 9 and the brake cylinder 5, allowing the brake cylinder 5 to be charged with air in one direction; the fourth mechanical valve 32 is connected to the atmosphere to release the pressure in the averaging pipe 15; by operating the second double-control plug 3, the work of the crew member getting off the train to open the plug of the averaging pipe in conventional technology can be avoided, thus improving work efficiency.

[0100] Furthermore, the third two-way valve 83 is configured to take the larger of its first and second inlets to select the larger of the first pre-control pressure P1 and the average pipe pressure PA to output as the seventh pre-control pressure P7 to the second inlet of the second two-way valve 82.

[0101] The second two-way valve 82 is configured to take the larger of its first and second inlets to select the larger of the sixth pre-control pressure P6 and the seventh pre-control pressure P7 to output the eighth pre-control pressure P8 to the control port of the relay valve 16.

[0102] The inlet of the relay valve 16 is connected to the main air 1 and the brake air cylinder 5, and its outlet is connected to the brake cylinder 17. It is configured to output the amplified eighth pre-control pressure P8 as the brake cylinder pressure PB to the brake cylinder 17 for braking.

[0103] As is well known to those skilled in the art, the connections between the various valves, air cylinders, components, and elements in this application can be made via pipelines to supply control air pressure; or via circuits, buses, etc., to supply electricity or electrical signals for the control of electric valves, such as electrically controlled valves and solenoid valves for filling and emptying. Furthermore, many of the pre-controlled pressures in this application, based on the context, may actually be the same pressure, but are represented by different designations due to their different locations or pipelines. On the same pipeline, different air pressures may also be used due to valve switching, etc.

[0104] The second embodiment of this application provides a locomotive braking control method (hereinafter referred to as the control method) with a fireless return function, which can employ the control system described in any of the preceding embodiments. The control method includes at least one of the following modes:

[0105] (1) Normal working mode (e.g.) Figure 2 (As shown)

[0106] In normal operating mode (non-flameless return mode), both the first dual-control plug 2 and the second dual-control plug 3 are in a non-flameless return state, such as... Figure 2 As shown. At this time, the first mechanical valve 21 of the first dual-control plug valve 2 is connected, and the second mechanical valve 22 is connected to the first inlet; the third mechanical valve 31 of the second dual-control plug valve 3 is cut off, and the fourth mechanical valve 32 is cut off.

[0107] The main air 1 reaches the brake air cylinder 5 through the first check valve 41, causing the pressure of the brake air cylinder 5 to rise to the pressure of the main air; when the locomotive needs to brake, the brake air cylinder 5 supplies air to the relay valve 16.

[0108] The air comes from the main air supply 1, and the fifth pre-control pressure P5 is obtained by the charging and discharging solenoid valve through charging and discharging, and reaches the second inlet of the switching valve 13. At this time, the electric control valve 14 is energized, so that the second inlet of the switching valve 13 is connected, and the fifth pre-control pressure P5 is output as the sixth pre-control pressure P6 to the first inlet of the second two-way valve 82.

[0109] When the locomotive is released, the train pipe 9 is filled with air to a constant pressure (emergency booster valve 7 is closed); at this time, the control fifth pre-control pressure P5 is reduced, the pressure at the control port of the relay valve 16 is discharged, and the brake cylinder pressure PB is not output.

[0110] When the locomotive is under normal braking, the fifth pre-control pressure P5 is increased, and after passing through the switching valve 13, it becomes the sixth pre-control pressure P6 (P6 = P5) and reaches the first inlet of the second two-way valve 82; the average pipe pressure PA reaches the second inlet of the third two-way valve 83, and after taking the larger value, the seventh pre-control pressure P7 (P7 = PA) is output to the second inlet of the second two-way valve 82; the second two-way valve 82 takes the larger value between P6 and P7 and outputs the eighth pre-control pressure P8 to the control port of the relay valve 16; the relay valve 16 outputs the required brake cylinder pressure PB through flow amplification for braking. At this time, the train pipe pressure drops from the constant pressure to the normal braking pressure, but the emergency booster valve 7 can still be kept closed, and the first pre-control pressure P1 is not output.

[0111] When the locomotive brakes suddenly, the pressure in train pipe 9 is rapidly released, the emergency booster valve 7 opens, and the main air 1 sequentially passes through the first check valve 141, the first pressure reducing valve 61, the emergency booster valve 7, and the first mechanical valve 21 of the first double-control plug valve 2 to output the first pre-control pressure P1 to the first inlet of the third two-way valve 83; the average pipe pressure PA reaches the second inlet of the third two-way valve 83; the third two-way valve 83 takes the larger of P1 and PA and outputs the seventh pre-control pressure P7 to the second inlet of the second two-way valve 82. The fifth pre-control pressure P5 still passes through the switching valve 13 to output the sixth pre-control pressure P6 (P6 = P5) to the first inlet of the second two-way valve 82; the second two-way valve 82 takes the larger of P6 and P7 and outputs the eighth pre-control pressure P8 to the control port of the relay valve 16, through which the required brake cylinder pressure PB is output for braking.

[0112] As mentioned earlier, the constant pressure of the train pipe is generally 500-600 kPa. It can be reduced to the normal braking pressure by the equalizing air cylinder, and can also be further emptied. From the constant pressure to the normal braking pressure, both are greater than the operating pressure of the emergency brake valve 7, causing the emergency booster valve to be in the off state. However, when the pressure in the train pipe 9 is emptied, the emergency booster valve 7 opens.

[0113] During normal braking of the locomotive, the mean pipe pressure PA and the fifth pre-control pressure P5 are redundant. During emergency braking of the locomotive, the mean pipe pressure PA and the first pre-control pressure P1 are redundant, and PA is also redundant with the fifth pre-control pressure P5; thus, the reliability of the system is guaranteed in multiple ways.

[0114] (2) Fifth pre-controlled pressure failure mode (such as...) Figure 3 (As shown)

[0115] In the fifth pre-control pressure P5 failure mode (non-flameless return mode), both the first dual-control valve 2 and the second dual-control valve 3 are also in a non-flameless return state, such as... Figure 3 As shown.

[0116] The main air 1 reaches the brake air cylinder 5 through the first check valve 41, causing the pressure of the brake air cylinder 5 to rise to the pressure of the main air; when the locomotive needs to brake, the brake air cylinder 5 supplies air to the relay valve 16.

[0117] At this time, due to the failure of the fifth pre-control pressure P5 (e.g., a fault in the charging / discharging solenoid valve), the electric control valve 14 loses power and switches to the first inlet of the connecting switching valve 13.

[0118] When the locomotive is released, the train pipe 9 is filled with air to a constant pressure; the working air cylinder 11 is filled to a constant pressure via the mechanical three-way valve 10; the mechanical three-way valve 10 does not output pressure to the working air cylinder 12. The pressure at the control port of the relay valve 16 is discharged, and the brake cylinder pressure PB is not output.

[0119] When the locomotive is under normal braking, the pressure in the train pipe drops from the constant pressure to the service braking pressure. The mechanical three-way valve 10 actuates, outputting the pressure from the working air cylinder 11 to the acting air cylinder 12, generating the service braking pressure as the second pre-control pressure P2. This second pre-control pressure P2 reaches the first inlet of the second mechanical valve 22 of the first double-control valve 2, and is output as the fourth pre-control pressure P4 to the first inlet of the switching valve 13. From the switching valve 13, the sixth pre-control pressure P6 (P6 = P4 = P2) is output to the first inlet of the second two-way valve 82. The average pipe pressure PA reaches the second inlet of the third two-way valve 83, and the larger of these pressures is output as the seventh pre-control pressure P7 (P7 = PA) to the second inlet of the second two-way valve 82. The second two-way valve 82 takes the larger of P6 and P7, outputting the eighth pre-control pressure P8 to the control port of the relay valve 16. The relay valve 16 then outputs the required brake cylinder pressure PB for braking. At this time, the train pipe pressure is the service braking pressure, which allows the emergency booster valve to remain closed, preventing the output of the first pre-control pressure P1.

[0120] When the locomotive brakes suddenly, the pressure in train pipe 9 is rapidly released, the emergency booster valve 7 opens, and the main air 1 sequentially passes through the first check valve 141, the first pressure reducing valve 61, the emergency booster valve 7, and the first mechanical valve 21 of the first double-control plug valve 2, outputting the first pre-control pressure P1 to the first inlet of the third two-way valve 83; the average pipe pressure PA reaches the second inlet of the third two-way valve 83; the third two-way valve 83 takes the larger of P1 and PA, outputting the seventh pre-control pressure P7 to the second inlet of the second two-way valve 82. The second pre-control pressure P2 from the mechanical three-way valve 10 is still input and output through the first inlet of the second mechanical valve 22 of the first double-control plug valve 2, and the fourth pre-control pressure P4 is output. Through the switching valve 13, the sixth pre-control pressure P6 (P6 = P4 = P2) is formed, reaching the first inlet of the second two-way valve 82. The second two-way valve 82 takes the larger of P6 and P7, outputting the eighth pre-control pressure P8 to the control port of the relay valve 16. The relay valve 16 outputs the required brake cylinder pressure PB through flow amplification for braking.

[0121] In this embodiment, when the electronic distribution valve pre-pressure (i.e., the fifth pre-control pressure P5) of the control system fails, it automatically switches to the mechanical three-way valve 10 for redundant control. The switching valve 13 is energized during normal operation and de-energized during redundant operation, so that even when the control system fails to receive power, the mechanical three-way valve 10 can still be used to control the brake cylinder pressure.

[0122] During normal braking of the locomotive, the mean pipe pressure PA and the second pre-control pressure P2 from the mechanical three-way valve 10 are redundant. During emergency braking of the locomotive, the mean pipe pressure PA and the first pre-control pressure P1 are redundant, and are also redundant with the second pre-control pressure P2 from the mechanical three-way valve 10; thus ensuring the reliability of the system in multiple ways.

[0123] (3) Fireless return mode (e.g.) Figure 4 (As shown)

[0124] In the flameless return mode, the entire control system loses power, and both the first dual-control gate 2 and the second dual-control gate 3 switch from the non-flameless return state to the flameless return state (this can be done manually); Figure 4 As shown. At this time, the first mechanical valve 21 of the first dual-control plug valve 2 is cut off, and the second mechanical valve 22 is connected to the second inlet; the third mechanical valve 31 of the second dual-control plug valve 3 is connected, and the port of the fourth mechanical valve 32 is emptied.

[0125] In the no-fire return mode, the pressure of the main air supply 1 is lost, and an external air source is used to pressurize the train pipe 9 to a constant pressure in order to supply air to the control system. The pressure of the train pipe passes sequentially through the third mechanical valve 31 and the second check valve 42 of the second double-control plug valve 3 to pressurize the brake cylinder 5 to a constant pressure. When the locomotive needs to brake, the brake cylinder 5 supplies air to the relay valve 16 and the first pressure reducing valve 61 (or the emergency pressure boosting valve 7). The first check valve 41 and the second check valve 42 respectively prevent the brake cylinder 5 from supplying air to the main air supply 1 and the train pipe 9 in reverse.

[0126] In the no-fire return mode, the electric control valve 14 is de-energized, and the first inlet of the switching valve 13 is connected.

[0127] When the locomotive is released, the train pipe 9 is purged to a constant pressure via an external air source; the working air cylinder 11 is then purged to a constant pressure via the mechanical three-way valve 10; the mechanical three-way valve 10 does not output pressure to the working air cylinder 12. The pressure at the control port of the relay valve 16 is released, and the brake cylinder pressure PB is not output.

[0128] When the locomotive is under normal braking, the pressure in the train pipe drops from the constant pressure to the service braking pressure. The mechanical three-way valve 10 is activated, outputting the pressure from the working air cylinder 11 to the acting air cylinder 12, generating the service braking pressure as the second pre-control pressure P2, which is output to the second inlet of the first two-way valve 81. After being increased by the first two-way valve 81 and reduced by the second pressure reducing valve 62 (P3'), it reaches the second inlet of the second mechanical valve 22 of the first double-control plug valve 2, which is output as the fourth pre-control pressure P4 to the first inlet of the switching valve 13. The sixth pre-control pressure P6 (P6 = P4 = P3') is output from the switching valve 13 to the first inlet of the second two-way valve 82. After being increased by the second two-way valve 82, the eighth pre-control pressure P8 is output to the control port of the relay valve 16. The required brake cylinder pressure PB is output through the relay valve 16 for braking. At this time, since the first mechanical valve 21 is shut off and the average pipe pressure PA is emptied by the fourth mechanical valve 32, the third two-way valve 83 has no output; it can be seen that the pre-control pressure at this time comes entirely from the mechanical three-way valve 10 and the actuating air cylinder 12. In addition, the pressure in the train pipe 9 is the normal braking pressure, which can still keep the emergency booster valve 7 closed and prevent the first pre-control pressure P1 from being output.

[0129] When the locomotive brakes suddenly, the pressure in the train pipe 9 is rapidly released, and the emergency booster valve 7 opens. Due to the reverse cutoff of the first check valve 41 and the second check valve 42, the pressure in the brake cylinder 5 is sequentially output through the first pressure reducing valve 61 and the emergency booster valve 7 to the first inlet of the first two-way valve 81, where the first pre-control pressure P1 is output. The second pre-control pressure P2 from the mechanical three-way valve 10 also reaches the first inlet of the first two-way valve 81. The first two-way valve 81 takes the larger of P1 and P2 and outputs the third pre-control pressure P3. After being reduced by the second pressure reducing valve 62 (P3'), it reaches the second inlet of the second mechanical valve 22 of the first double-control plug valve 2, and is output as the fourth pre-control pressure P4 to the first inlet of the switching valve 13. The sixth pre-control pressure P6 (P6 = P4 = P3') is output from the switching valve 13 to the first inlet of the second two-way valve 82. The eighth pre-control pressure P8 is output through the second two-way valve 82 to the control port of the relay valve 16. The required brake cylinder pressure PB is output through the flow amplification function of the relay valve 16 for braking. At this time, the third two-way valve 83 still has no output.

[0130] In the fireless return mode, the fourth mechanical valve 32 is connected to the atmosphere to release the pressure in the averaging pipe 15; thereby automatically releasing the pressure in the averaging pipe without the need for manual operation.

[0131] During normal braking of the locomotive, braking pressure is provided solely by the second pre-control pressure P2 from the mechanical three-way valve 10. During emergency braking of the locomotive, the first pre-control pressure P1 and the second pre-control pressure P2 from the mechanical three-way valve 10 are redundant to ensure the reliability of the system.

[0132] The control method provided in this application allows for brake cylinder pressure control during fireless return when the locomotive needs to perform a fireless return operation. This is achieved by the crew operating a stop valve, which, based on the mechanical three-way valve of a conventional locomotive brake control system. The fireless return mode can be directly set by switching the stop valve position, and it also realizes complex functions such as pressure limiting by the mechanical three-way valve, emergency pressure boosting and limiting, air supply from the train pipe to the brake cylinder, and emptying the averaging pipe.

[0133] In some embodiments of this application, the pressure loss of the brake cylinder during the no-fire return braking mode is prevented by using a first check valve and a second check valve. Pressure control during emergency braking in the no-fire return mode is achieved by using a first two-way valve.

[0134] In some practical operations, the emergency booster valve is triggered at a pressure exceeding 135 kPa. When the train pipe experiences emergency ventilation, the emergency booster valve returns to its initial position, mechanically boosting the brake cylinder for emergency braking. The mechanical three-way valve continues to respond to the maximum service braking pressure during emergency braking, with both functions serving as redundancy to improve the reliability of emergency braking.

[0135] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0136] The above embodiments are only used to illustrate the technical solutions of this application and not to limit them; although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of this application or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of this application, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in this application.

Claims

1. A locomotive braking control system with fireless return function, characterized in that, include: The main air supply, after passing through the first check valve, is connected to the brake cylinder and the emergency booster valve respectively. The main air supply is configured to: be able to charge the brake cylinder in one direction, be able to output the first pre-control pressure P1 through the emergency booster valve, and allow the pressure of the brake cylinder to reach the emergency booster valve without flowing back to the main air supply. Train pipe; its control port, which is connected to the emergency booster valve, can provide control pressure; its air inlet, which is connected to the mechanical three-way valve, can charge the mechanical three-way valve; and its first port, which is connected to the third mechanical valve of the second double-control valve, can charge the brake cylinder. The emergency booster valve has an inlet connected to the main air supply and an outlet connected to the inlet of the first mechanical valve of the first double-control plug valve and the first inlet of the first bidirectional valve, respectively, and is capable of outputting a first pre-control pressure P1; the emergency booster valve also has a control port connected to the train pipe, which is capable of controlling the opening or closing of the emergency booster valve. The mechanical three-way valve has an air inlet connected to the train pipe and is connected to the working air cylinder and the actuating air cylinder respectively. The mechanical three-way valve is configured to: use the pressure of the train pipe to charge air to the working air cylinder; when the pressure of the train pipe drops, the pressure of the working air cylinder can be connected to the actuating air cylinder to control the actuating air cylinder to generate a second pre-control pressure P2; the second pre-control pressure P2 can reach the second inlet of the first two-way valve and the first inlet of the second mechanical valve of the first double-control plug valve respectively. The first two-way valve; It is configured to take the larger of its first and second inlets and output the third pre-control pressure P3 to the second inlet of the second mechanical valve of the first double-control plug valve; The first dual-control valve has a first mechanical valve and a second mechanical valve that can be linked together. The first mechanical valve has an inlet and an outlet, and the second mechanical valve has an outlet and a first inlet and a second inlet that can be switched. The first dual-control valve is configured such that: in the non-flame-free return state, the inlet and outlet of the first mechanical valve are connected to output a first pre-control pressure P1, and the first inlet of the second mechanical valve is connected to its outlet to output a second pre-control pressure P2 as a fourth pre-control pressure P4; in the flame-free return state, the first mechanical valve is shut off, and the second inlet of the second mechanical valve is connected to its outlet to output a third pre-control pressure P3 as the fourth pre-control pressure P4. The second dual-control valve has at least a third mechanical valve; the first port of the third mechanical valve is connected to the train pipe, and the second port is connected to the brake cylinder; the second dual-control valve is configured such that: in the non-flame-free return state, the first and second ports of the third mechanical valve are cut off; in the flame-free return state, the first and second ports of the third mechanical valve are connected, enabling air to be supplied to the brake cylinder through the train pipe; The second check valve is located between the train pipe and the brake cylinder and is configured to allow unidirectional airflow from the train pipe to the brake cylinder and not allow reverse airflow. A switching valve; the first inlet of the switching valve is connected to the outlet of the second mechanical valve of the first double-controlled plug valve, and can input a fourth pre-control pressure P4; the second inlet of the switching valve is connected to a fifth pre-control pressure P5; the outlet of the switching valve is connected to the first inlet of the second bidirectional valve; the switching valve is configured to be able to switch between its first inlet and second inlet to output one of the fourth pre-control pressure P4 and the fifth pre-control pressure P5 as a sixth pre-control pressure P6 to the first inlet of the second bidirectional valve; The second two-way valve; the first inlet of the second two-way valve is connected to the outlet of the switching valve, and the second inlet of the second two-way valve is connected to the outlet of the first mechanical valve of the first double-control plug valve; the outlet of the second two-way valve is connected to the control port of the relay valve; the second two-way valve is configured to: take the larger of its first inlet and second inlet, and select the larger pressure as the eighth pre-control pressure P8 to be output to the control port of the relay valve; as well as, The relay valve; the inlet of the relay valve is connected to the main air supply and the brake cylinder, and its outlet is connected to the brake cylinder; the relay valve is configured to: amplify the flow rate at the inlet of the relay valve according to the eighth pre-control pressure P8 at the control port of the relay valve, and output the brake pressure PB to the brake cylinder for braking.

2. The control system according to claim 1, characterized in that, It also includes an average pipe and a third two-way valve capable of outputting the average pipe pressure PA; The second dual-control plug valve also has a fourth mechanical valve that can be linked with the third mechanical valve; the port of the fourth mechanical valve can switch between shutting off and opening to the atmosphere. The outlet of the first mechanical valve is connected to the first inlet of the third two-way valve, and can output the first pre-control pressure P1; the averaging pipe is connected to the second inlet of the third two-way valve and the port of the fourth mechanical valve respectively; The outlet of the third bidirectional valve is connected to the second inlet of the second bidirectional valve; the third bidirectional valve is configured to select the larger pressure between its first inlet and second inlet as the seventh pre-control pressure P7 and output it to the second inlet of the second bidirectional valve. The second dual-control valve is configured such that, in the non-flame-free return state, the first and second ports of the third mechanical valve are shut off, and the port of the fourth mechanical valve is shut off; in the flame-free return state, the first and second ports of the third mechanical valve are connected, enabling unidirectional air supply to the brake cylinder through the train pipe, and the fourth mechanical valve is connected to the atmosphere, enabling the discharge of the average pipe pressure PA.

3. The control system according to claim 1 or 2, characterized in that, A second pressure reducing valve is provided between the outlet of the first two-way valve and the second inlet of the second mechanical valve to adjust the pressure entering the second inlet of the second mechanical valve.

4. The control system according to claim 3, characterized in that, A third check valve, connected in parallel with the second pressure reducing valve, is provided between the outlet of the first two-way valve and the second inlet of the second mechanical valve. This check valve allows pressure to flow from the second inlet of the second mechanical valve to the outlet of the first two-way valve, but does not allow reverse flow.

5. The control system according to claim 1, 2 or 4, characterized in that, The switching valve has a control port; the inlet of the electrically controlled valve is connected to the main air supply, and the outlet of the electrically controlled valve is connected to the control port of the switching valve; the electrically controlled valve is configured to: when energized, connect the main air supply and the control port of the switching valve, so that the second inlet of the switching valve is connected, and output the fifth pre-control pressure P5 as the sixth pre-control pressure P6; when de-energized, disconnect the main air supply and the control port of the switching valve, switch the switching valve to the first inlet connection, and output the fourth pre-control pressure P4 as the sixth pre-control pressure P6.

6. The control system according to claim 1, 2 or 4, characterized in that, A first pressure reducing valve is provided between the first check valve and the emergency pressure boosting valve to adjust the pressure entering the emergency pressure boosting valve.

7. The control system according to claim 1, 2 or 4, characterized in that, The second check valve is located between the second port of the third mechanical valve and the brake cylinder.

8. The control system according to claim 1, 2 or 4, characterized in that, The fifth pre-controlled pressure P5 comes from the main air supply and is obtained by the charging and discharging solenoid valve through charging and discharging.

9. A locomotive braking control method with fireless return function, characterized in that, The control system according to any one of claims 1-8, wherein the control method comprises at least one of the following modes: Normal working mode: In normal operating mode, both the first and second dual-control valves are in a non-flame-free return state; at this time, the inlet and outlet of the first mechanical valve are connected, the first inlet and outlet of the second mechanical valve are connected, and the third mechanical valve is shut off. The main air supply reaches the brake cylinder through the first check valve to charge it; when the locomotive needs to brake, the brake cylinder supplies air to the relay valve; the main air supply also reaches the inlet of the emergency booster valve through the first check valve. At this time, the second inlet and outlet of the switching valve are connected, and the fifth pre-control pressure P5 can be output as the sixth pre-control pressure P6 to the first inlet of the second bidirectional valve. When the locomotive is released, the train pipe is purged to a constant pressure and the emergency booster valve is closed; at this time, the fifth pre-control pressure P5 is reduced, the pressure at the control port of the relay valve is released, and the brake cylinder pressure PB is not output. When the locomotive is under normal braking, the fifth pre-control pressure P5 is increased and passes through the switching valve to become the sixth pre-control pressure P6, which reaches the first inlet of the second two-way valve. The second two-way valve takes the larger value and outputs the eighth pre-control pressure P8, which reaches the control port of the relay valve. The relay valve outputs the required brake cylinder pressure PB through flow amplification to brake. At this time, the train pipe pressure drops from the constant pressure to the normal braking pressure, the emergency booster valve remains closed, and the first pre-control pressure P1 is not output to the second inlet of the second two-way valve. When the locomotive brakes suddenly, the pressure in the train pipe is rapidly released, the emergency booster valve opens, and the main air sequentially passes through the first check valve, the emergency booster valve, and the first mechanical valve to output the first pre-control pressure P1 to the second inlet of the second two-way valve; the fifth pre-control pressure P5 is still output through the switching valve as the sixth pre-control pressure P6 to the first inlet of the second two-way valve; the second two-way valve takes the larger of the first pre-control pressure P1 and the sixth pre-control pressure P6 and outputs the eighth pre-control pressure P8 to the control port of the relay valve, which then outputs the required brake cylinder pressure PB for braking. Fifth Pre-Controlled Pressure Failure Mode In the fifth pre-control pressure P5 failure mode, both the first and second dual-control valves are in a non-flame-free return state; at this time, the inlet and outlet of the first mechanical valve are connected, the first inlet and outlet of the second mechanical valve are connected, and the third mechanical valve is shut off. The main air supply reaches the brake cylinder through the first check valve to charge it; when the locomotive needs to brake, the brake cylinder supplies air to the relay valve; the main air supply also reaches the inlet of the emergency booster valve through the first check valve. At this time, since the fifth pre-control pressure P5 fails, the switching valve switches to the first inlet and outlet connection, and can output the fourth pre-control pressure P4 as the sixth pre-control pressure P6 to the first inlet of the second two-way valve. When the locomotive is released, the train pipe is filled with air to a constant pressure, and the working air cylinder is filled to a constant pressure through the mechanical three-way valve; the mechanical three-way valve does not output pressure to the working air cylinder; the pressure at the control port of the relay valve is discharged and the brake cylinder pressure PB is not output. When the locomotive is under normal braking, the pressure in the train pipe drops from the constant pressure to the normal braking pressure. The mechanical three-way valve activates, outputting the pressure from the working air cylinder to the actuating air cylinder, generating a second pre-control pressure P2. This second pre-control pressure P2 reaches the first inlet of the second mechanical valve and is output as the fourth pre-control pressure P4 to the first inlet of the switching valve. The sixth pre-control pressure P6 is then output from the switching valve to the first inlet of the second bidirectional valve. The second bidirectional valve takes the larger value and outputs the eighth pre-control pressure P8 to the control port of the relay valve. The relay valve outputs the required brake cylinder pressure PB for braking. At this time, the train pipe pressure drops from the constant pressure to the normal braking pressure, and the emergency booster valve remains closed, not outputting the first pre-control pressure P1 to the second inlet of the second bidirectional valve. When the locomotive brakes suddenly, the pressure in the train pipe is rapidly released, the emergency booster valve opens, and the main air sequentially passes through the first check valve, the emergency booster valve, and the first mechanical valve to output the first pre-control pressure P1 to the second inlet of the second two-way valve. The second pre-control pressure P2 from the mechanical three-way valve is still input through the first inlet of the second mechanical valve and outputs the fourth pre-control pressure P4. Through the switching valve, the sixth pre-control pressure P6 is formed and reaches the first inlet of the second two-way valve. The second two-way valve takes the larger of the first pre-control pressure P1 and the sixth pre-control pressure P6 and outputs the eighth pre-control pressure P8 to the control port of the relay valve. The relay valve outputs the required brake cylinder pressure PB through flow amplification to brake. Fireless return mode In the flameless return mode, both the first and second dual-control plugs switch from the non-flameless return state to the flameless return state; at this time, the first mechanical valve is shut off, the second inlet and outlet of the second mechanical valve are connected; the first port and the second port of the third mechanical valve are connected, and the port of the fourth mechanical valve is connected to the atmosphere. At this time, the pressure of the main air is lost, and an external air source is used to fill the train pipe with air to a constant pressure so as to supply air to the control system; the pressure of the train pipe passes through the third mechanical valve and the second check valve to fill the brake cylinder with constant pressure; when the locomotive needs to brake, the brake cylinder supplies air to the relay valve and the emergency booster valve respectively, and the first check valve and the second check valve prevent the brake cylinder from supplying air to the main air and the train pipe in reverse. At this time, the first inlet and outlet of the switching valve are connected, and the fourth pre-control pressure P4 can be output as the sixth pre-control pressure P6 to the first inlet of the second two-way valve. When the locomotive is released, the train pipe is filled with air to a constant pressure through an external air source, and then the working air cylinder is filled to a constant pressure through a mechanical three-way valve; the mechanical three-way valve does not output pressure to the working air cylinder; the pressure at the control port of the relay valve is discharged and the brake cylinder pressure PB is not output. When the locomotive is under normal braking, the pressure in the train pipe drops from the constant pressure to the service braking pressure. The mechanical three-way valve activates, outputting the pressure from the working air cylinder to the actuating air cylinder, generating a second pre-control pressure P2, which is output to the second inlet of the first two-way valve. After being maximized by the first two-way valve, a third pre-control pressure P3 is output to the second inlet of the second mechanical valve, which serves as the fourth pre-control pressure P4, output to the first inlet of the switching valve. A sixth pre-control pressure P6 is also output from the switching valve to the first inlet of the second two-way valve. After being maximized by the second two-way valve, an eighth pre-control pressure P8 is output to the control port of the relay valve. The relay valve then outputs the required brake cylinder pressure PB for braking. At this time, the pressure in the train pipe is the service braking pressure, the emergency booster valve remains closed, and the first pre-control pressure P1 is not output to the first inlet of the first two-way valve. The first mechanical valve is shut off, and there is no input to the second inlet of the second two-way valve. When the locomotive brakes suddenly, the pressure in the train pipe is rapidly released, and the emergency booster valve opens. Due to the reverse cutoff of the first and second check valves, the pressure in the brake cylinder is output as the first pre-control pressure P1 via the emergency booster valve, reaching the first inlet of the first two-way valve. The second pre-control pressure P2 from the mechanical three-way valve also reaches the first inlet of the first two-way valve. The first two-way valve takes the larger of the first and second pre-control pressures P1 and outputs the third pre-control pressure P3, which reaches the second inlet of the second mechanical valve. This third pre-control pressure P4 is then output to the first inlet of the switching valve, and the sixth pre-control pressure P6 is output from the switching valve to the first inlet of the second two-way valve. The second two-way valve takes the larger of the pre-control pressures P8, which is then output to the control port of the relay valve. The relay valve amplifies the flow and outputs the required brake cylinder pressure PB for braking. At this time, due to the cutoff of the first mechanical valve, the second inlet of the second two-way valve still has no input.

10. A locomotive braking control method with fireless return function, characterized in that, The control system according to any one of claims 2-8, wherein the control method comprises at least one of the following modes: Normal working mode In normal operating mode, both the first and second dual-control valves are in a non-flame-free return state; at this time, the inlet and outlet of the first mechanical valve are connected, the first inlet and outlet of the second mechanical valve are connected, the third mechanical valve is shut off, and the port of the fourth mechanical valve is shut off. The main air supply reaches the brake cylinder through the first check valve to charge it; when the locomotive needs to brake, the brake cylinder supplies air to the relay valve; the main air supply also reaches the inlet of the emergency booster valve through the first check valve. At this time, the second inlet and outlet of the switching valve are connected, and the fifth pre-control pressure P5 can be output as the sixth pre-control pressure P6 to the first inlet of the second bidirectional valve. When the locomotive is released, the train pipe is purged to a constant pressure and the emergency booster valve is closed; at this time, the fifth pre-control pressure P5 is reduced, the pressure at the control port of the relay valve is released, and the brake cylinder pressure PB is not output. When the locomotive is under normal braking, the fifth pre-control pressure P5 is increased and passes through the switching valve to become the sixth pre-control pressure P6, reaching the first inlet of the second two-way valve; the average pipe pressure PA reaches the second inlet of the third two-way valve, and the larger of the two pressures is taken to output the seventh pre-control pressure P7 to the second inlet of the second two-way valve; the second two-way valve takes the larger of the sixth pre-control pressure P6 and the seventh pre-control pressure P7, and outputs the eighth pre-control pressure P8 to the control port of the relay valve; the relay valve outputs the required brake cylinder pressure PB through flow amplification to brake; at this time, the train pipe pressure drops from the constant pressure to the normal braking pressure, the emergency booster valve remains closed, and the first pre-control pressure P1 is not output to the first inlet of the third two-way valve; When the locomotive brakes suddenly, the pressure in the train pipe is rapidly released, the emergency booster valve opens, and the main air sequentially passes through the first check valve, the emergency booster valve, and the first mechanical valve to output the first pre-control pressure P1 to the first inlet of the third two-way valve; the average pipe pressure PA reaches the second inlet of the third two-way valve; the third two-way valve takes the larger of the first pre-control pressure P1 and the average pipe pressure PA, and outputs the seventh pre-control pressure P7 to the second inlet of the second two-way valve; the fifth pre-control pressure P5 still passes through the switching valve to output the sixth pre-control pressure P6 to the first inlet of the second two-way valve; the second two-way valve takes the larger of the sixth pre-control pressure P6 and the seventh pre-control pressure P7, and outputs the eighth pre-control pressure P8 to the control port of the relay valve, through which the required brake cylinder pressure PB is output for braking; Fifth Pre-Controlled Pressure Failure Mode In the fifth pre-control pressure P5 failure mode, both the first and second dual-control valves are in a non-flame-free return state; at this time, the inlet and outlet of the first mechanical valve are connected, the first inlet and outlet of the second mechanical valve are connected, the third mechanical valve is cut off, and the port of the fourth mechanical valve is cut off. The main air supply reaches the brake cylinder through the first check valve to charge it; when the locomotive needs to brake, the brake cylinder supplies air to the relay valve; the main air supply also reaches the inlet of the emergency booster valve through the first check valve. At this time, since the fifth pre-control pressure P5 fails, the switching valve switches to the first inlet and outlet connection, and can output the fourth pre-control pressure P4 as the sixth pre-control pressure P6 to the first inlet of the second two-way valve. When the locomotive is released, the train pipe is filled with air to a constant pressure, and the working air cylinder is filled to a constant pressure through the mechanical three-way valve; the mechanical three-way valve does not output pressure to the working air cylinder; the pressure at the control port of the relay valve is discharged and the brake cylinder pressure PB is not output. When the locomotive is under normal braking, the pressure in the train pipe drops from the constant pressure to the normal braking pressure. The mechanical three-way valve activates, outputting the pressure from the working air cylinder to the actuating air cylinder, generating a second pre-control pressure P2. This second pre-control pressure P2 reaches the first inlet of the second mechanical valve and is output as the fourth pre-control pressure P4 to the first inlet of the switching valve. From the switching valve, the sixth pre-control pressure P6 is output to the first inlet of the second bidirectional valve. The average pipe pressure PA reaches the second inlet of the third bidirectional valve, and the larger of the two pressures is taken to output the seventh pre-control pressure P7 to the second inlet of the second bidirectional valve. The second bidirectional valve takes the larger of the sixth and seventh pre-control pressures P6 and outputs the eighth pre-control pressure P8 to the control port of the relay valve. The relay valve then outputs the required brake cylinder pressure PB for braking. At this time, the train pipe pressure drops from the constant pressure to the normal braking pressure, the emergency booster valve remains closed, and the first pre-control pressure P1 is not output to the first inlet of the third bidirectional valve. When the locomotive brakes suddenly, the pressure in the train pipe is rapidly released, the emergency booster valve opens, and the main air sequentially passes through the first check valve, the emergency booster valve, and the first mechanical valve to output the first pre-control pressure P1 to the first inlet of the third two-way valve; the average pipe pressure PA reaches the second inlet of the third two-way valve; the third two-way valve takes the larger of the first pre-control pressure P1 and the average pipe pressure PA, and outputs the seventh pre-control pressure P7 to the second inlet of the second two-way valve; the second pre-control pressure P2 from the mechanical three-way valve is still input through the first inlet of the second mechanical valve and outputs the fourth pre-control pressure P4, which is formed by the switching valve to form the sixth pre-control pressure P6, reaching the first inlet of the second two-way valve; the second two-way valve takes the larger of the sixth pre-control pressure P6 and the seventh pre-control pressure P7, and outputs the eighth pre-control pressure P8 to the control port of the relay valve; the relay valve outputs the required brake cylinder pressure PB through flow amplification to brake; Fireless return mode In the flameless return mode, both the first and second dual-control plugs switch from the non-flameless return state to the flameless return state; at this time, the first mechanical valve is shut off, the second inlet and outlet of the second mechanical valve are connected; the first port and the second port of the third mechanical valve are connected, and the port of the fourth mechanical valve is connected to the atmosphere. At this time, the pressure of the main air is lost, and an external air source is used to fill the train pipe with air to a constant pressure so as to supply air to the control system; the pressure of the train pipe passes through the third mechanical valve and the second check valve to fill the brake cylinder with constant pressure; when the locomotive needs to brake, the brake cylinder supplies air to the relay valve and the emergency booster valve respectively, and the first check valve and the second check valve prevent the brake cylinder from supplying air to the main air and the train pipe in reverse. At this time, the first inlet and outlet of the switching valve are connected, and the fourth pre-control pressure P4 can be output as the sixth pre-control pressure P6 to the first inlet of the second two-way valve. When the locomotive is released, the train pipe is filled with air to a constant pressure through an external air source; the working air cylinder is filled to a constant pressure through a mechanical three-way valve; the mechanical three-way valve does not output pressure to the working air cylinder; the pressure at the control port of the relay valve is discharged and the brake cylinder pressure PB is not output. When the locomotive is under normal braking, the pressure in the train pipe drops from the constant pressure to the normal braking pressure. The mechanical three-way valve activates, outputting the pressure from the working air cylinder to the acting air cylinder, generating a second pre-control pressure P2, which is output to the second inlet of the first two-way valve. After being maximized by the first two-way valve, the third pre-control pressure P3 is output to the second inlet of the second mechanical valve, serving as the fourth pre-control pressure P4, which is output to the first inlet of the switching valve. The sixth pre-control pressure P6 is output from the switching valve to the first inlet of the second two-way valve. After being maximized by the second two-way valve, the eighth pre-control pressure P8 is output to the control port of the relay valve. The relay valve then outputs the required brake cylinder pressure PB for braking. At this time, since the first mechanical valve is shut off and the average pipe pressure PA is emptied by the fourth mechanical valve, the third two-way valve has no output. In addition, the pressure in the train pipe is the normal braking pressure, and the emergency booster valve remains closed, not outputting the first pre-control pressure P1 to the first inlet of the first two-way valve. When the locomotive brakes suddenly, the pressure in the train pipe is rapidly released, and the emergency booster valve opens. Due to the reverse cutoff of the first and second check valves, the pressure in the brake cylinder is output as the first pre-control pressure P1 via the emergency booster valve, reaching the first inlet of the first two-way valve. The second pre-control pressure P2 from the mechanical three-way valve also reaches the first inlet of the first two-way valve. The first two-way valve takes the larger of the first and second pre-control pressures P1 and outputs the third pre-control pressure P3, which reaches the second inlet of the second mechanical valve. This third pre-control pressure P4 is then output to the first inlet of the switching valve, and the sixth pre-control pressure P6 is output from the switching valve to the first inlet of the second two-way valve. The second two-way valve takes the larger of the pre-control pressures P8, which is then output to the control port of the relay valve. The relay valve amplifies the flow and outputs the required brake cylinder pressure PB for braking. At this time, the third two-way valve still has no output.

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