Pneumatic control unit for a rail vehicle brake system

Abstract

The application provides a pneumatic control unit of a rail vehicle braking system, comprising a pressure control module, a gas path selection module and a pressure output control module, wherein: the pressure control module is used for adjusting the pressure value of the input total air pressure and outputting a control pressure to the gas path selection module according to a control instruction; the gas path selection module is used for realizing that multiple control pressure inputs correspond to one output pressure to the pressure output control module or multiple control pressure inputs are parallel output to the pressure output control module according to the control instruction; and the pressure output control module is used for realizing the connection and cutting off of the input pressure of each pneumatic actuator. The pneumatic control unit has programmability, and the existence of the pressure control module and the gas path selection module makes the pneumatic control unit adapt to the braking systems of different types of rail transit or motor train vehicle after rewriting the gas path timing logic and pressure control logic in the control software, and has good versatility.

Description

Technical Field

[0001] This invention relates to the field of rail vehicle control technology, and in particular to a pneumatic control unit for a rail vehicle braking system. Background Technology

[0002] Rail vehicle braking systems can be categorized into electric braking and friction braking based on their application method. Electric braking decelerates the train by using a motor driven by the wheel axle to generate electricity in reverse. Friction braking decelerates the train through friction between the brake disc or tread and the friction pair. Due to its superior reliability and braking efficiency, friction braking has become an indispensable part of existing rail vehicle braking systems. Based on the driving method, friction braking can be further divided into electric drive and pneumatic drive. Electric drive uses electrical energy as its source, controlling the motor to achieve braking, such as electric brake calipers. Pneumatic drive uses compressed air generated by an air compressor, achieving corresponding braking functions through different pneumatic components, such as filling the brake cylinder with compressed air to push the brake caliper to clamp the brake disc. Pneumatic drive has become the most widely used driving method in rail vehicle braking systems due to the easy availability of gas, low storage requirements, and stable operation. Besides friction braking, functions such as pantographs, sand spreading, and door control also utilize pneumatic drives. Therefore, the integration of multiple functions requires modular design of the pneumatic control system to form a pneumatic control unit, thereby increasing the efficiency of function implementation.

[0003] like Figure 1 The diagram shows the output relationship of the pneumatic control unit in an existing rail vehicle braking system. The input to the pneumatic control unit consists of three parts: compressed air, power supply, and pneumatic control commands. Compressed air is generated by an air compressor. The function of the pneumatic control unit is to adjust the input compressed air, which has a single pressure value, to output compressed air with different values ​​and flow rates at each output terminal as needed. An external power supply powers the actuators such as solenoid valves in the pneumatic control unit. The electronic braking control unit outputs pneumatic control commands to control the output pressure to achieve the functional objectives. The function of the pneumatic control unit can be reflected by pressure values ​​and pressure action. Pressure values ​​are collected by pressure sensors within the pneumatic control unit and fed back to the electronic braking control unit for closed-loop control of pressure values ​​and fault diagnosis of pneumatic components. Pressure action manifests as driving the pneumatic actuators; for example, compressed air can drive the pantograph to rise, providing power to the train.

[0004] like Figure 2The diagram shows the internal structure of the pneumatic control unit in an existing rail vehicle braking system. The pneumatic control unit generally consists of an air supply and air spring module, a braking control module, a parking control module, a pantograph raising control module, a sand spreading control module, and a pressure switch module. These modules all take the total air pressure as input directly or indirectly. After adjusting the pressure / flow rate, the modules output to various pneumatic actuators, such as brake cylinders, parking cylinders, pantographs, sand boxes, and air springs.

[0005] The air supply and air spring module is mainly used to provide adjusted pressure to the braking control module and parking control module, as well as to provide suitable pressure to the train's air springs. The module includes one-way valves and isolation plugs to control the direction and on / off of the air path, pressure sensors and pressure measuring points to collect pressure, pressure reducing valves and relief valves to control pressure values, and filters to control air quality. The compressed air adjusted by the air supply and air spring module is divided into three paths: one directly provides pressure to the air springs, and the other two paths enter the braking control module and parking control module respectively.

[0006] The braking control module controls the brake cylinder pressure during service braking and emergency braking, enabling the train to decelerate according to different braking forces. When the train is in service braking mode, the braking system, based on the pressure sensor values ​​in the module, controls the EP solenoid valve to adjust the pre-control pressure, which is then used to generate the target brake cylinder pressure via a pressure reducing valve and a relay valve. During emergency braking, the empty / load valve adjusts the corresponding emergency pre-control pressure based on the vehicle weight collected by the sensor. This pressure is then passed through the emergency solenoid valve, and the corresponding emergency braking force is generated by switching between the solenoid valve and the relay valve. The release solenoid valve is used to release the train's braking force in case of a malfunction.

[0007] The parking brake module controls the pressure of the train's parking cylinder to prevent runaway when the train is stationary. When the parking cylinder has pressure, the parking brake is released; when there is no pressure, the parking brake is applied. The parking brake module further adjusts the pressure provided by the air supply and air spring modules through a pressure reducing valve, and then controls the passage and discharge of compressed air through a parking solenoid valve to achieve the charging and discharging of the parking cylinder. The two-way check valve in the module ensures parking brake release when there is brake cylinder pressure; that is, when the brake control module outputs brake cylinder pressure, it automatically charges the parking cylinder to release the parking brake. The release solenoid valve is used to manually release the parking brake in case of a train malfunction.

[0008] In addition to the main modules mentioned above, the pantograph raising control module supplies compressed air to the pantograph raising actuator. A check valve controls the gas flow to prevent backflow when the main duct pressure is low, ensuring sufficient pressure for the pantograph to rise. After entering the sand spreading control module, the compressed air first passes through a pressure reducing valve for pressure adjustment, and then through a drying solenoid valve to blow air into the sand box for sand spreading and drying. When the train needs sand spreading, it is controlled by the sand spreading solenoid valve. The main air pressure also supplies air directly to the waste discharge and toilets through an overflow valve.

[0009] As can be seen from the above, the pneumatic control units of existing rail vehicles are mostly modularly designed based on functions. Different combinations of components are used inside the modules to regulate the total input air pressure and flow rate, and output to various pneumatic actuators. The components inside the pneumatic control unit are mainly divided into four categories: (1) Measurement: pressure sensors, pressure measuring points, pressure switches. (2) Air circuit opening and closing, direction control: various solenoid valves, check valves, bidirectional check valves, isolation plugs. (3) Pressure regulation: EP solenoid valves, relay valves, pressure reducing valves, overflow valves. (4) Gas quality control: filters. However, facing the future development trend of miniaturization, lightweighting and intelligence of the pneumatic control units of rail vehicles, the modular and inherited design concept has become a bottleneck, which has at least the following defects:

[0010] 1. The large size and weight of components such as empty and heavy valves and relay valves are not conducive to lightweight and miniaturized design.

[0011] 2. If a critical component in a module fails, the entire module will fail, which is detrimental to safety.

[0012] 3. When facing different vehicle requirements, the components in the module require a large number of parameter modifications and layout redesigns, which reduces reuse efficiency.

[0013] 4. Component diagnosis in the control unit relies on sensors, but due to design constraints, the number of sensors is insufficient to achieve accurate fault location at the component level. Summary of the Invention

[0014] In view of this, the present invention provides a pneumatic control unit for a rail vehicle braking system to solve at least one of the aforementioned problems.

[0015] To achieve the above objectives, the present invention adopts the following solution:

[0016] This invention provides a pneumatic control unit for a rail vehicle braking system. The pneumatic control unit includes a pressure control module, an air path selection module, and a pressure output control module. The input terminal of the pressure control module is connected to the total air pressure. The air path selection module is connected to both the pressure control module and the pressure output control module. The output terminal of the pressure output control module is connected to each pneumatic actuator. Specifically: the pressure control module adjusts the input total air pressure according to control commands and outputs a control pressure to the air path selection module; the air path selection module, according to control commands, allows multiple control pressure inputs to correspond to a single output pressure, or allows multiple control pressure inputs to be output in parallel to the pressure output control module; the pressure output control module enables the connection and disconnection of input pressures to each pneumatic actuator.

[0017] Preferably, in this embodiment of the invention, the pressure control module includes two flow controllers and one precision controller. The flow controllers and the precision controller have the same structure, both consisting of four solenoid valves. The air passage diameter when the solenoid valves in the flow controllers are open is larger than that in the precision controllers.

[0018] Preferably, in this embodiment of the invention, the four solenoid valves in the flow controller and the precision controller are: a first function reversal solenoid valve, an air charging solenoid valve, a second function reversal solenoid valve, and an exhaust solenoid valve. The first function reversal solenoid valve has three connection ports, one of which is connected to the total air pressure, one of which is connected to the air charging solenoid valve, and the other of which is connected to the atmosphere. The second function reversal solenoid valve also has three connection ports, one of which is connected to the total air pressure, one of which is connected to the exhaust solenoid valve, and the other of which is connected to the atmosphere. The other ends of the air charging solenoid valve and the exhaust solenoid valve are both connected to the air path selection module.

[0019] Preferably, in the embodiments of the present invention, the first function reversing solenoid valve enables the air charging solenoid valve to have an exhaust function, and the second function reversing solenoid valve enables the exhaust solenoid valve to have an air charging function.

[0020] Preferably, in this embodiment of the invention, the gas path selection module includes multiple gas path selection controllers. Each gas path selection controller includes an input terminal, a first output terminal, a second output terminal, and a solenoid valve. One end of the solenoid valve serves as the input terminal, one end as the first output terminal, and the other end as the second output terminal. The solenoid valve can select the first output terminal or the second output terminal to output according to a control command. The solenoid valves of the multiple gas path selectors can be cascaded so that the first output terminal or the second output terminal of one solenoid valve is connected to the input terminal of another solenoid valve.

[0021] Preferably, in this embodiment of the invention, the output terminals of the two flow controllers and one precision controller are each connected to the input terminal of a different gas path selection controller, and the gas path selectors directly connected to the output terminals of the two flow controllers and one precision controller are all the first-stage gas path selectors in a cascaded gas path selector.

[0022] Preferably, in this embodiment of the invention, the gas path selection module further includes multiple pressure sensors, the number of which is the same as the number of gas path selection controllers, and the pressure sensors are respectively arranged at the input end of the gas path selection controllers.

[0023] Preferably, in this embodiment of the invention, the pressure output control module includes multiple output enable controllers, wherein the output enable controller is a solenoid valve used to connect and disconnect the input pressure of the corresponding pneumatic actuator according to the control command.

[0024] Preferably, in this embodiment of the invention, the pressure output control module further includes a plurality of pressure sensors, the number of which is the same as the number of output enable controllers, and the pressure sensors are respectively disposed at the output end of the output enable controller.

[0025] Preferably, in this embodiment of the invention, the pressure sensor in the air path selection module and the pressure sensor in the pressure output control module send the pressure value to the external electronic brake control unit, which then performs fault diagnosis of the pneumatic control unit based on the pressure value.

[0026] As can be seen from the above technical solution, the pneumatic control unit of the rail vehicle braking system provided by the present invention has programmability in pneumatic control. The input end of the pneumatic control unit is the total air pressure, and the output end can be connected to different pneumatic actuators according to actual functional requirements. The existence of the pressure control module and the air path selection module makes it possible to adapt to the braking systems of different types of rail transit or EMU vehicles after rewriting the air path timing logic and pressure control logic in the control software, thus having good versatility. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0028] Figure 1 This is a diagram showing the output relationships of the pneumatic control unit in an existing rail vehicle braking system;

[0029] Figure 2 This is a schematic diagram of the internal modules of the pneumatic control unit in an existing rail vehicle braking system;

[0030] Figure 3 This is a schematic diagram of the structure of a pneumatic control unit for a rail vehicle braking system provided in an embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the internal structure of the flow controller and the precision controller provided in the embodiments of this application;

[0032] Figure 5 This is a schematic diagram of a cascaded solenoid valve between pneumatic path selection controllers provided in an embodiment of this application;

[0033] Figure 6 This is an overall schematic diagram of the air path selection module of the pneumatic control unit provided in an embodiment of the present invention;

[0034] Figure 7 This is a schematic diagram of the structure of an output enable controller provided in this embodiment;

[0035] Figure 8 This is a schematic diagram showing the connection relationship between the pneumatic control unit and peripheral equipment provided in an embodiment of the present invention;

[0036] Figure 9 This is a schematic flowchart of the pneumatic control method for performing a general braking function provided in an embodiment of the present invention;

[0037] Figure 10 This is a schematic flowchart of a pneumatic control method for performing emergency braking function according to another embodiment of the present invention. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0039] like Figure 3 The diagram shows a pneumatic control unit for a rail vehicle braking system according to an embodiment of the present invention. The pneumatic control unit includes a pressure control module 100, an air path selection module 200, and a pressure output control module 300, wherein the air path selection module 200 is connected to the pressure control module 100 and the pressure output control module 300 respectively.

[0040] The input terminal of the pressure control module 100 is the total air pressure, which is generated by the air compressor in the rail vehicle. The pressure control module 100 can adjust the input total air pressure according to the control command and then output the control pressure to the air path selection module 200. The control command here comes from the electronic brake control unit that is externally connected to the pneumatic control unit.

[0041] Preferably, the pressure control module 100 in this embodiment includes two flow controllers and one precision controller. The flow controllers and precision controllers have identical structures; both can be composed of four solenoid valves. The difference is that the air passage diameter when the solenoid valves in the flow controllers are open is larger than that in the precision controllers. The flow controller prioritizes flow rate over precision, aiming to quickly raise the target pressure in the opening direction to a specified value, with less emphasis on pressure control precision. Conversely, the precision controller prioritizes control precision and can accurately control the target pressure in the opening direction. Of course, those skilled in the art can also set different numbers of flow controllers or precision controllers based on the disclosure in this application to achieve corresponding pressure control objectives.

[0042] like Figure 4 The diagram shown is a schematic representation of the internal structure of the flow controller and precision controller provided in an embodiment of this application. Figure 4 As can be seen, the four solenoid valves in the flow controller and precision controller are the function reversal solenoid valve 1, the air charging solenoid valve, the air exhaust solenoid valve, and the function reversal solenoid valve 2. The function reversal solenoid valve 1 has three connection ports, one of which is connected to the total air pressure, one of which is connected to the air charging solenoid valve, and the other of which is connected to the atmosphere. The function reversal solenoid valve 2 also has three connection ports, one of which is connected to the total air pressure, one of which is connected to the air exhaust solenoid valve, and the other of which is connected to the atmosphere. The air charging solenoid valve and the air exhaust solenoid valve each have two ports, and their other ends are connected to the air path selection module 200.

[0043] The following is about Figure 4 The working principles of the flow controller and precision controller shown are explained below:

[0044] All four solenoid valves mentioned above include both position 1 and position 2. They can determine whether gas flows through position 1 or position 2 based on control commands from an external electronic brake control unit. Figure 4 Taking the air-filling solenoid valve as an example, when there is no control command, the input and output of the air-filling solenoid valve are connected through 1 bit, and the input and output are cut off. When there is a control command indicating that it is connected, the input and output of the air-filling solenoid valve are connected through 2 bits, and the input and output are connected.

[0045] In this embodiment, Figure 4When there is no control command, all four solenoid valves are connected to the input and output at position 1. At this time, the total air pressure is connected to the input of the air charging solenoid valve through the function reversal solenoid valve 1. The input and output of the air charging solenoid valve are cut off, the input and output of the exhaust solenoid valve are cut off, and the output of the exhaust solenoid valve is connected to the atmosphere through position 1 of the function reversal solenoid valve 2.

[0046] During non-emergency braking of the railcar, both the function reversing solenoid valve 1 and function reversing solenoid valve 2 are connected to the input and output at position 1. If an increase in pressure is needed at the output, the charging solenoid valve is activated for a certain period, connecting to the input and output at position 2 to charge compressed air into the output. When the output pressure reaches the target value, the charging solenoid valve is connected to the input and output at position 1 to stop charging. The exhaust solenoid valve operates similarly; when a decrease in output pressure is needed, it is connected to the input and output at position 2 to exhaust compressed air to the atmosphere. During emergency braking of the railcar, when an increase in output pressure is needed, function reversing solenoid valve 2 is first connected to the input and output at position 2. Then, both the charging and exhaust solenoid valves are simultaneously connected to the input and output at position 2. This effectively converts the exhaust solenoid valve into a charging solenoid valve, with both valves simultaneously increasing pressure at the output, reducing the response time for pressure rise. When emergency braking and ventilation are required, the control function reversal solenoid valve 1 is connected to the input / output at position 2, while the function reversal solenoid valve 2 remains connected to the input / output at position 1. This effectively converts the charging solenoid valve into a venting solenoid valve, allowing both valves to simultaneously discharge compressed air from the output, reducing the pressure drop response time. Depending on the specific braking function's requirements for response time and control precision, the three controllers (two flow controllers and one precision controller) can either simultaneously switch functions and operate concurrently, prioritizing response time for rapid pressure adjustment of a single path, or first use the flow controllers to quickly adjust the pressure to near the target value, and then use the precision controller for fine-tuning within a small range to achieve precise pressure control.

[0047] In this embodiment, the gas path selection module 200 is used to implement multiple control pressure inputs corresponding to one output pressure to the pressure output control module 300 according to control commands, or to implement multiple control pressure inputs to be output in parallel to the pressure output control module. If the pressure control module 100 includes two flow controllers and one precision controller, then the gas path selection module 200 can be used to connect the output control pressures of the three controllers in the pressure control module 100 to multiple target pressure output terminals in the pressure output control module 300. For example, if there are ten target pressure output terminals, then the gas path selection module 200 should be able to connect any one of the three inputs to any one of the ten outputs, and can support three parallel outputs.

[0048] Preferably, the gas path selection module 200 includes multiple gas path selection controllers. Each gas path selection controller includes an input terminal, an output terminal 1, an output terminal 2, and a solenoid valve. The solenoid valve has three ports: one as an input terminal, one as a first output terminal, and one as a second output terminal. The solenoid valve can select either the first or second output terminal to output according to a control command. Furthermore, the solenoid valves of the multiple gas path selectors can be cascaded, allowing the first or second output terminal of one solenoid valve to be connected to the input terminal of another solenoid valve. For example... Figure 5 The diagram shown is a schematic diagram of a cascaded solenoid valve between pneumatic path selection controllers according to an embodiment of this application. Figure 5 The solenoid valve in the system can select output terminal 1 or connect the output terminal to the input terminal based on the presence or absence of a control command. When output terminal 2 is connected to the input terminal, it introduces gas from the left gas path into the right gas path, serving as the input to the solenoid valve in the right gas path. Therefore, cascading two solenoid valves can connect the pressure of one input terminal to the three target pressure output terminals in the pressure output control module 300. Thus, multiple gas path selection controllers can be connected as needed to achieve multiple inputs to one output or multiple inputs outputting in parallel.

[0049] Preferably, in this embodiment, the output terminals of the two flow controllers and the precision controller are each connected to the input terminal of a different gas path selection controller. The gas path selectors directly connected to the output terminals of the two flow controllers and the precision controller are all the first-stage gas path selectors in the cascaded gas path selector. Therefore, by cascading the gas path selectors, three parallel outputs can be achieved, and any one of the three inputs can be connected to any one of the outputs.

[0050] like Figure 6 The diagram shown is an overall schematic diagram of the air path selection module of the pneumatic control unit provided in this embodiment of the invention. In this embodiment, 10 common functional execution terminals that require pneumatic control (brake cylinder, parking cylinder, sand spreading, bow lifting, tread cleaning, toilet, air conditioning, horn, door, sand box drying) are selected to illustrate the working principle of the air path selection module 200. Figure 6The middle arrow indicates the permitted gas flow direction within the module, while the black dots represent the air path switching solenoid valves and pressure sensors. The functional execution terminals connected to the output terminals are arranged from left to right according to the frequency, importance, and control precision required. For example, the brake cylinder stores compressed air to push the calipers and generate friction braking force; its pressure value directly affects the train's braking force and braking distance, requiring precise control, therefore it is located on the far left of the output terminal. Parking cylinder pressure, sand-spreading pressure, etc., also require pressure value control to achieve their functions, but their usage frequency is less than that of the brake cylinder, so they are arranged on the left. Other functions, due to their lower pressure requirements and lower control frequency, are arranged on the right. The input terminal of the precision controller is also located on the left side of the module input terminal. When precise control response is required, the precision controller has a direct air path to achieve its control function, avoiding interruption of other flow control processes. The two air path switching solenoid valves at the lower left of the diagram are used for rapid response during emergency braking. Upon input of an emergency braking command, two solenoid valves connect air path branches 2 and 3 to air path branch 1, enabling three controllers to rapidly charge or exhaust air from the brake cylinder, reducing response time. The 24 solenoid valves at the top of the diagram allow three controllers (two flow controllers and one precision controller) to simultaneously control the pressure of any three of the ten output channels. Thanks to the pressure sensor matrix, when a sensor indicates a fault in a corresponding air path or solenoid valve, the fault location can be determined and the air path switched. For example, if air path branch 1 malfunctions, the solenoid valve can be switched to allow compressed air to pass through air path branches 2 or 3, ultimately reaching the brake cylinder output.

[0051] In this embodiment, the pressure output control module 300 is used to connect and disconnect the input pressure of each pneumatic actuator, or to cooperate with the air path selection module 200 to achieve related functions. Preferably, the pressure output control module 300 may include multiple output enable controllers, such as... Figure 7 The diagram shows a schematic of an output enable controller provided in this embodiment. This output enable controller is a solenoid valve used to connect and disconnect the input pressure of the corresponding pneumatic actuator according to control commands. To achieve motion control of the corresponding pneumatic actuator, each output to the pneumatic actuator in this embodiment corresponds to an output enable controller. When there is no output command by default, the input and output terminals of the output enable controller are disconnected to prevent residual pressure from other control actions in the gas path selection module 200 from affecting the current output. When there is a control output command for this path, the input and output terminals of the output enable controller are connected, allowing gas to enter the corresponding pneumatic actuator.

[0052] Preferably, the gas path selection module 200 may further include multiple pressure sensors, the number of which is the same as the number of gas path selection controllers in the gas path selection module 200. Each pressure sensor is correspondingly located at the input terminal of the gas path selection controller. For specific configuration details, please refer to the above description. Figure 5 , Figure 5 The symbol P in the middle refers to the pressure sensor of the gas path selection module 200.

[0053] Preferably, the pressure output control module 300 may also include multiple pressure sensors, the number of which is the same as the number of output enable controllers in the pressure output control module 300. Each pressure sensor is correspondingly disposed at the output terminal of the output enable controller. For specific configuration details, please refer to [reference needed]. Figure 7 , Figure 7 P in the middle refers to the pressure sensor of the output control module 300.

[0054] Both the pressure sensor in the air path selection module 200 and the pressure sensor in the pressure output control module 300 can send pressure values ​​to an external electronic brake control unit, which then uses these pressure values ​​to diagnose faults in the pneumatic control unit. By configuring these pressure sensors, at least two pressure sensors can perform redundant pressure acquisition when pressure control is applied to a specific pneumatic actuator. The pressure sensor in the air path selection module 200 can also diagnose the status of the internal air path, determining whether the air path switching was successful or, based on the consistency of multiple sensor values, whether a leak exists in a specific part of the air path.

[0055] The pneumatic control unit provided by this invention relies on multiple peripheral devices for its functionality, such as... Figure 8The diagram illustrates the connection between the pneumatic control unit and peripheral equipment provided in this embodiment of the invention. The electronic brake control unit provides pneumatic control commands to the pneumatic control unit and corrects these commands based on the pressure values ​​at each measuring point fed back by the pneumatic control unit. It also performs fault diagnosis of the pneumatic control unit. The pneumatic control commands are divided into four parts: pressure value control command, controller function reversal command, air path adjustment control command, and output permission control command. The pressure value control command controls the opening and closing actions and duration of the solenoid valves in the two flow controllers and one precision controller to achieve a controlled pressure to a specified target value. The controller function reversal command enables the solenoid valves in the two flow controllers and one precision controller to switch between charging and discharging functions, reducing response time during emergency braking application and release. The air path adjustment control command controls the gas flow path in the control unit, allowing the same controller to control different outputs and multiple controllers to simultaneously control one output. The output permission command controls whether a specified output is allowed to output. When the required pressure value for a certain output reaches the target, the output permission for that port is disabled, releasing the air path occupancy in the pneumatic control unit and allowing other pneumatic control functions to execute. The compressed air required by the pneumatic control unit is generated by the air compressor in the train and directly input to the three controllers in the unit. To ensure control reliability, the different components of the pneumatic control unit are powered independently; the three controllers, air path switching control and pressure output control, each use separate power supply modules. Multiple output terminals of the pneumatic control unit are connected to corresponding pneumatic actuators, such as brake cylinders, parking cylinders, and sand-spreading devices.

[0056] When the aforementioned pneumatic control unit performs a general braking function pneumatic task, its implementation process may include, for example: Figure 9 The steps shown are as follows:

[0057] Step S901: Receive the control command for the pneumatic task to be performed.

[0058] Step S902: Check whether the pressure control module is idle and available according to the control command. If it is idle and available, proceed to step S903; otherwise, proceed to step S904.

[0059] Step S903: Calculate whether there is an available airflow path in the air path selection module. If there is, proceed to step S905; otherwise, proceed to step S904.

[0060] Step S904: Query the priority of the pneumatic task to be executed. If the priority is higher than the previously executed task, pause the previously executed task and proceed to step S905. Otherwise, wait for the previously executed task to complete before proceeding to step S905.

[0061] Step S905: Check whether the pressure output control module allows output, and perform pressure control on the pneumatic actuator corresponding to the pneumatic task to be performed based on the query result.

[0062] In this embodiment, the pneumatic task refers to a pneumatic task that performs general braking functions, i.e., a pneumatic task excluding emergency braking. The sand-spreading function is used as an example to illustrate the above implementation process. The sand-spreading function requires initial pressure control using a flow controller, followed by precise pressure control using a precision controller. When a sand-spreading command is issued or the sand-spreading pressure needs adjustment, it is necessary to first check whether the required flow controller and precision controller are occupied by other tasks. If occupied, the priority of the sand-spreading control task needs to be checked and compared with the priority of already executed tasks. If the priority is higher, the already executed task can be paused. If a high-priority task, such as emergency braking, is being executed, the sand-spreading should be performed only after the task is completed. Once the controller is available, it is also necessary to check whether the air path is available. Then, based on the query result and the task priority, the task is executed or waited for. Finally, it is necessary to check whether the corresponding output terminal allows output, and output pressure control is performed based on the query result.

[0063] When the aforementioned pneumatic control unit performs the pneumatic task of emergency braking, its implementation process may include, for example: Figure 10 The steps shown are as follows:

[0064] Step S1001: Receive the control command for the emergency braking task to be performed;

[0065] Step S1002: Check whether the pressure control module is idle and available according to the control command. If it is idle and available, proceed to step S1003; otherwise, proceed to step S1004.

[0066] Step S1003: Calculate whether there is an available airflow path in the air path selection module. If there is, proceed to step S1005; otherwise, proceed to step S1004.

[0067] Step S1004: Pause all ongoing pneumatic tasks and proceed to step S1005;

[0068] Step S1005: The forced control pressure output control module allows the output channel corresponding to the emergency braking task to be connected, and uses the pressure control module to adjust the pressure value to achieve rapid air charging of the brake cylinder.

[0069] Emergency braking is the most important and highest priority function of the train's air braking system. When an emergency braking command is issued, the availability of the controllers is checked first. If all three controllers are unavailable, the corresponding control task is suspended. Similarly, if the airflow path is blocked, the corresponding task is also suspended. After forcibly enabling output through the corresponding output channel, the exhaust valve of the brake controller is reversed to rapidly charge air according to the deceleration value. Due to the aforementioned structure of the pneumatic control unit, the output of the solenoid valve can be reversed during emergency braking to ensure the flow rate meets the requirements for emergency braking time response. Furthermore, it can continuously control the emergency braking output pressure. Assuming the train decelerates at the adhesion limit during emergency braking, the required pressure needs to continuously vary from 200-400 kPa. However, existing technologies rely on mechanical switching of pressure changing valves, which can only switch abruptly between a few pressure values ​​(e.g., 200-300-400), resulting in poor adhesion utilization. This embodiment uses a controller to continuously control the pressure during emergency braking, ensuring the braking force conforms to the adhesion curve, thus reducing the braking distance during emergency braking.

[0070] As can be seen from the above, the pneumatic control unit of the rail vehicle braking system provided by the present invention has the following beneficial effects:

[0071] First, the input of the pneumatic control unit is the total air pressure, and the output can be connected to different pneumatic actuators according to actual functional requirements. The existence of the pressure control module and the air path selection module allows the air path timing logic and pressure control logic in the control software to be rewritten to adapt to the braking systems of different types of rail transit or EMU vehicles. It can be seen that the programmability of the present invention in pneumatic control makes the present invention have good versatility.

[0072] Secondly, it has the advantages of miniaturization and lightweight design. Compared with the pneumatic control unit of the traditional braking system, it eliminates heavy and bulky components such as relay valves, empty / load valves, and check valves, and replaces them with small and lightweight solenoid valves. On this basis, the air circuit layout is optimized, which can effectively reduce the size and weight of the pneumatic control unit.

[0073] Third, it boasts excellent maintainability and high control reliability. The gas path selection module employs a pressure sensor array, and each output terminal also has a pressure sensor, allowing for rapid location of the fault in case of a control unit malfunction. Since the controller uses only solenoid valves, the types of spare parts and the complexity of replacement are greatly reduced. The presence of multiple pressure sensors in a single path enhances the reliability of pressure acquisition during pressure control, thereby increasing the overall reliability of pressure control.

[0074] Fourth, compared with the existing emergency braking adhesion control based on the mechanical ratio of relay valve, the three pressure / flow control cores of the pneumatic control unit described in this invention are all independently powered, and can change the function of a single solenoid valve during emergency braking, change the pressure output direction of the exhaust solenoid valve, and use the controller to continuously control the pressure of the brake cylinder, so that the train decelerates at the adhesion limit, resulting in faster braking response time and shorter braking distance. When the emergency braking is released, the pressure output direction of the charging solenoid valve is changed again, resulting in less release time.

[0075] Fifth, it can achieve redundant control of all pneumatic control functions. When the current control function's air path selection fails or the controller fails, another pair of controllers can be selected to switch to another air path, ensuring the stability of the braking control function.

[0076] Sixth, it can increase the energy efficiency ratio of the air braking system. Taking sand spreading control as an example, the existing sand spreading pressure of EMU trains is divided into two parts: high-speed high pressure and low-speed low pressure. When the train speed drops to a certain point, it is achieved through mechanical switching. However, with the application of a programmable pneumatic control unit, the sand spreading pressure can be continuously adjusted according to the train speed, reducing pressure waste when approaching low-speed sections, while increasing the utilization efficiency of sand spreading.

[0077] Preferred embodiments of the invention have been described above with reference to the accompanying drawings. Many features and advantages of these embodiments are apparent from this detailed description, and therefore the claims are intended to cover all such features and advantages of these embodiments that fall within their true spirit and scope. Furthermore, since many modifications and alterations will readily occur to those skilled in the art, the embodiments of the invention are not intended to be limited to the precise structures and operations illustrated and described, but rather to encompass all suitable modifications and equivalents falling within their scope.

Claims

1. A pneumatic control unit for a rail vehicle braking system, characterized in that, The pneumatic control unit includes a pressure control module, an air path selection module, and a pressure output control module. The pressure control module's input is connected to the total air pressure. The air path selection module is connected to both the pressure control module and the pressure output control module. The output of the pressure output control module is connected to each pneumatic actuator. Specifically: the pressure control module adjusts the input total air pressure according to control commands and then outputs a control pressure to the air path selection module; the air path selection module, according to control commands, allows multiple control pressure inputs to correspond to a single output pressure, or allows multiple control pressure inputs to be output to the pressure output control module in parallel; the pressure output control module enables the connection and disconnection of input pressures for each pneumatic actuator. The pressure control module includes two flow controllers and one precision controller. The flow controller and the precision controller have the same structure, both consisting of four solenoid valves. The air passage diameter when the solenoid valve in the flow controller is open is larger than that when the solenoid valve in the precision controller is open. The gas path selection module includes multiple gas path selection controllers. Each gas path selection controller includes an input terminal, a first output terminal, a second output terminal, and a solenoid valve. One end of the solenoid valve serves as the input terminal, one end as the first output terminal, and the other end as the second output terminal. The solenoid valve can select the first output terminal or the second output terminal to output according to the control command. The solenoid valves of the multiple gas path selection controllers can be cascaded, so that the first output terminal or the second output terminal of one solenoid valve is connected to the input terminal of another solenoid valve.

2. The pneumatic control unit of the rail vehicle braking system as described in claim 1, characterized in that, The flow controller and the precision controller contain four solenoid valves: a first function reversing solenoid valve, an air charging solenoid valve, a second function reversing solenoid valve, and an exhaust solenoid valve. The first function reversing solenoid valve has three connection ports, one of which is connected to the total air pressure, one of which is connected to the air charging solenoid valve, and the other of which is connected to the atmosphere. The second function reversing solenoid valve also has three connection ports, one of which is connected to the total air pressure, one of which is connected to the exhaust solenoid valve, and the other of which is connected to the atmosphere. The other ends of the air charging solenoid valve and the exhaust solenoid valve are both connected to the air path selection module.

3. The pneumatic control unit of the rail vehicle braking system as described in claim 2, characterized in that, The first function reversing solenoid valve enables the air-charging solenoid valve to have an exhaust function, and the second function reversing solenoid valve enables the exhaust solenoid valve to have an air-charging function.

4. The pneumatic control unit of the rail vehicle braking system as described in claim 1, characterized in that, The outputs of the two flow controllers and the precision controller are each connected to the input of a different gas path selection controller. The gas path selectors directly connected to the outputs of the two flow controllers and the precision controller are all the first-stage gas path selectors in a cascaded gas path selector.

5. The pneumatic control unit of the rail vehicle braking system as described in claim 1, characterized in that, The gas path selection module also includes multiple pressure sensors, the number of which is the same as the number of gas path selection controllers, and the pressure sensors are respectively set at the input terminals of the gas path selection controllers.

6. The pneumatic control unit of the rail vehicle braking system as described in claim 1, characterized in that, The pressure output control module includes multiple output enable controllers, each of which is a solenoid valve used to connect and disconnect the input pressure of the corresponding pneumatic actuator according to control commands.

7. The pneumatic control unit of the rail vehicle braking system as described in claim 6, characterized in that, The pressure output control module also includes multiple pressure sensors, the number of which is the same as the number of output enable controllers, and the pressure sensors are respectively set at the output terminals of the output enable controllers.

8. The pneumatic control unit of the rail vehicle braking system as described in claim 5 or 7, characterized in that, The pressure sensor in the air path selection module and the pressure sensor in the pressure output control module send the pressure value to the external electronic brake control unit, which then performs fault diagnosis on the pneumatic control unit based on the pressure value.

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