A method and device for troubleshooting natural release failure of a railway wagon brake

Abstract

The application discloses a kind of railway freight car brake natural relief troubleshooting method and device, wherein the method comprises: by single vehicle tester or locomotive brake to the train pipe, auxiliary air cylinder and slow air cylinder of railway freight car brake is filled to first pressure, after stabilizing, train pipe pressure is reduced to second pressure after pressure maintaining is carried out;After train pipe pressure stabilizes, the pressure value of train pipe, auxiliary air cylinder, slow air cylinder and brake cylinder is read for the first time by pressure sensor;After waiting for a period of time, when railway freight car brake occurs natural relief failure, i.e. brake cylinder pressure suddenly drops, the pressure value of train pipe, auxiliary air cylinder, slow air cylinder and brake cylinder is read for the second time by pressure sensor;Based on the pressure value change of train pipe, auxiliary air cylinder, slow air cylinder and brake cylinder read before and after, the cause of railway freight car brake natural relief failure is judged by differential pressure troubleshooting method or curve slope troubleshooting method.The application realizes the rapid troubleshooting of natural relief failure.

Description

Technical Field

[0001] The present invention relates to the technical field of freight train braking, and particularly to a method and device for troubleshooting the natural release failure of a railway freight car brake. Background Art

[0002] The railway freight car brake is a core component to ensure the safe operation of freight trains. Under the control of the locomotive brake, it can, according to the change of the train pipe pressure, make the brake produce release, braking, and pressure holding effects, so as to control the vehicle in different operating states.

[0003] At present, the 120-type air control valve is the main type of product for the railway freight car brake in China. Its braking function and technical parameters not only meet the needs of the freight car running at 120 km / h, but also meet the requirements of braking and synchronous operation for long formation heavy-haul trains with a capacity of 10,000 tons and above. It has a milestone significance in the development history of railway freight car braking technology in China and provides guarantee for freight transportation safety.

[0004] As Figure 1 shown, the 120-type air control valve is externally connected to four pipe systems, namely the train pipe, the auxiliary air cylinder pipe (auxiliary air cylinder), the accelerating and buffering air cylinder pipe (accelerating and buffering air cylinder), and the brake cylinder pipe (brake cylinder). Its function has a direct relationship with these four pipe systems. The main working principle of the 120-type control valve is: when the train pipe is depressurized, the pressure of the auxiliary air cylinder is used to fill the brake cylinder through the 120-type control valve, that is, the braking effect occurs; when the train pipe stops depressurizing and remains unchanged, the passage between the auxiliary air cylinder and the brake cylinder is disconnected, and the pressures of the auxiliary air cylinder and the brake cylinder remain unchanged, which is the pressure holding effect; when the train pipe is 6 - 16 kPa higher than the auxiliary air cylinder, the 120-type control valve enters the release position, the train pipe communicates with the auxiliary air cylinder, fills the auxiliary air cylinder, and the brake cylinder vents to the atmosphere and drops to 0, which is the release effect; at the same time of the release effect, when the exhaust pressure of the brake cylinder vents to the atmosphere, it will open the sandwich valve passage between the accelerating and buffering air cylinder and the train pipe, make the accelerating and buffering air cylinder communicate with the train pipe, and accelerate the pressure rise of the train pipe to improve the release rate, which is the accelerating and buffering effect.

[0005] With the continuous improvement of the train running speed and safety requirements, each vehicle production unit and maintenance unit have raised the maintenance standards of vehicle brakes during single vehicle tests. Limited by test conditions, the vehicle brake is basically in a static state during single vehicle tests, while during operation, it is affected by multiple factors such as vibration, impact, and temperature. Therefore, faults of freight car brakes still inevitably exist, which to a certain extent affect the train running safety and reduce the freight transportation efficiency.

[0006] Natural relaxation is a common fault of the freight car brake. That is, after braking and maintaining pressure, the pressure of the train pipe remains unchanged and is in a holding state. The control valve itself should be in a pressure-holding state, and the pressure of the brake cylinder remains unchanged. However, due to certain reasons, the brake undergoes natural relaxation, resulting in the pressure of the brake cylinder dropping to 0. The main function of pressure-reducing braking is for vehicle speed regulation or operations before parking. Once natural relaxation occurs, it may lead to out-of-control vehicle running speed, inability to stop, and even dangerous consequences such as vehicle rolling.

[0007] The single-vehicle performance test of the railway freight car brake is carried out by a freight car single-vehicle tester according to the standard of TB / T 1492 "Single-Vehicle Test of Railway Vehicle Brakes". The single-vehicle test of the freight car braking system is judged by using the pressure values of the train pipe and the brake cylinder collected by the pressure sensor, as Figure 2 shown. After the natural relaxation fault occurs, the following main defects exist: (1) It can only judge whether natural relaxation occurs, but directly cannot judge the root cause of natural relaxation. By detecting the pressure value of the brake cylinder, it can be judged that the vehicle brake has undergone natural relaxation. However, due to limited data, the cause of this fault cannot be determined.

[0008] (2) Disassembly may lead to distortion of the fault judgment result. Usually, the 120 control valve is disassembled for a single-valve test to verify whether it is qualified. The bumps during disassembly and transportation will affect the internal structure state of the 120 valve. (3) The troubleshooting of natural relaxation fault factors is incomplete. The natural relaxation fault is directly related to the 120 control valve, pipe system, and air cylinder. Only relying on the two sensors of the train pipe and the brake cylinder cannot accurately locate the cause of the fault. Summary of the Invention

[0009] To solve the above problems, the present invention proposes a method and device for troubleshooting natural relaxation faults of railway freight car brakes. Without disassembling the 120-type control valve while keeping the configuration of the railway freight car brake unchanged, pressure sensors corresponding to the train pipe, auxiliary air cylinder, acceleration and buffer air cylinder, and brake cylinder are quickly installed in each pipeline. The data acquisition and processing equipment is used to read each pressure value, and based on this, the root cause of the natural relaxation of the railway freight car brake is judged, so as to quickly troubleshoot the natural relaxation fault.

[0010] The technical solution adopted by the present invention is as follows: A method for troubleshooting natural relaxation faults of railway freight car brakes includes: Data acquisition: Charge the train pipe, auxiliary air cylinder, and buffer air cylinder of the railway freight car brake to the first pressure through a single-car tester or locomotive brake. After stabilization, reduce the train pipe pressure to the second pressure and then hold the pressure. After the train pipe pressure stabilizes, read the pressure values of the train pipe, auxiliary air cylinder, buffer air cylinder, and brake cylinder for the first time through a pressure sensor. After waiting for a period of time, when the railway freight car brake has a natural release failure, that is, when the brake cylinder pressure suddenly drops, read the pressure values of the train pipe, auxiliary air cylinder, buffer air cylinder, and brake cylinder for the second time through the pressure sensor; Fault analysis: Based on the changes in the pressure values of the train pipe, auxiliary air cylinder, buffer air cylinder, and brake cylinder read before and after, judge the cause of the natural release failure of the railway freight car brake through the differential pressure troubleshooting method or the curve slope troubleshooting method.

[0011] Further, the causes of the natural release failure of the railway freight car brake judged by the differential pressure troubleshooting method include: If the auxiliary air cylinder pressure drops, the buffer air cylinder remains unchanged, and the train pipe remains unchanged, it indicates a leak in the auxiliary air cylinder pipe system; If the brake cylinder pressure drops, and the train pipe, auxiliary air cylinder, and buffer air cylinder remain unchanged, it indicates a leak in the brake cylinder pipe system; If the buffer air cylinder pressure drops, the train pipe pressure rises, and the auxiliary air cylinder remains unchanged, it indicates a leak in the sandwich valve between the buffer air cylinder and the train pipe in the control valve; If the train pipe pressure rises, and the auxiliary air cylinder and buffer air cylinder remain unchanged, it indicates that there is no fault in the railway freight car brake.

[0012] Further, the causes of the natural release failure of the railway freight car brake judged by the curve slope troubleshooting method include: Record the pressure values of the train pipe, auxiliary air cylinder, buffer air cylinder, and brake cylinder read for the first time as L1, F1, J1, and Z1 respectively, and record the time T1; Record the pressure values of the train pipe, auxiliary air cylinder, buffer air cylinder, and brake cylinder read for the second time as L2, F2, J2, and Z2 respectively, and record the time T2; Calculate the pressure change slopes of the train pipe, auxiliary air cylinder, buffer air cylinder, and brake cylinder: X , L [(L2 - L1) / (T2 - T1)], X F [(F2 - F1) / (T2 - T1)], X J [(J2 - J1) / (T2 - T1)], X Z [(Z2 - Z1) / (T2 - T1)]; Judge the cause of the natural release failure according to the pressure change slope: If X F is negative, and X J、 X L remains unchanged, it indicates a leak in the auxiliary air cylinder pipe system; If X J、 X F、 X L remains unchanged and X Z is negative, it indicates a leakage in the brake cylinder pipe system; If X J is negative, X L is positive, and X F remains unchanged, it indicates a leakage in the sandwich valve between the buffer cylinder and the train pipe in the control valve; If X L is positive, X J、 X F、 remains unchanged, it indicates that there is no fault in the railway freight car brake;

[0013] Further, after the train pipe, auxiliary reservoir, and buffer cylinder are charged to the first pressure and stabilized, a small reduction brake is performed and held at the second pressure, that is, the difference between the first pressure and the second pressure is not greater than 100 kPa, so that there are pressures in the train pipe, auxiliary reservoir, buffer cylinder, and brake cylinder.

[0014] Further, the pressure sensor is installed through a quick-connect plug. One end of the quick-connect plug is provided with a first-size thread, which is consistent with the pressure sensor interface; the other end is provided with a second-size thread, which is consistent with the tapered thread of the brake pipe system or the air cylinder, and the outer diameter of the second-size thread is smaller than the major diameter of the standard thread; the joint surface of the quick-connect plug is provided with a groove for placing an O-ring.

[0015] A device for troubleshooting the natural release failure of a railway freight car brake includes: A data acquisition module. After the train pipe, auxiliary reservoir, and buffer cylinder of the railway freight car brake are charged to the first pressure by a single-car tester or a locomotive brake, and after the train pipe pressure is reduced to the second pressure and held stable, the data acquisition module reads the pressure values of the train pipe, auxiliary reservoir, buffer cylinder, and brake cylinder for the first time through the pressure sensor; after waiting for a period of time, when the railway freight car brake has a natural release failure, that is, when the brake cylinder pressure suddenly drops, the data acquisition module reads the pressure values of the train pipe, auxiliary reservoir, buffer cylinder, and brake cylinder for the second time through the pressure sensor; A data processing module, configured to judge the cause of the natural release failure of the railway freight car brake based on the change of the pressure values of the train pipe, auxiliary reservoir, buffer cylinder, and brake cylinder read twice before and after, by using the differential pressure troubleshooting method or the curve slope troubleshooting method.

[0016] Further, the data processing module judges the cause of the natural release failure of the railway freight car brake by using the differential pressure troubleshooting method, including: If the auxiliary reservoir pressure drops, the buffer cylinder remains unchanged, and the train pipe remains unchanged, it indicates a leakage in the auxiliary reservoir pipe system; If the pressure in the brake cylinder drops while the train pipe, auxiliary reservoir, and buffer cylinder remain unchanged, it indicates a leakage in the brake cylinder pipe system. If the pressure in the buffer cylinder drops, the pressure in the train pipe rises, and the auxiliary reservoir remains unchanged, it indicates a leakage in the sandwich valve between the buffer cylinder and the train pipe in the control valve. If the pressure in the train pipe rises and the auxiliary reservoir and buffer cylinder remain unchanged, it indicates that there is no fault in the railway freight car brake.

[0017] Furthermore, the data processing module determines the cause of the natural release failure of the railway freight car brake through the curve slope detection method, including: Record the pressure values of the train pipe, auxiliary reservoir, buffer cylinder, and brake cylinder read for the first time as L1, F1, J1, and Z1 respectively, and record the time T1. Record the pressure values of the train pipe, auxiliary reservoir, buffer cylinder, and brake cylinder read for the second time as L2, F2, J2, and Z2 respectively, and record the time T2. Calculate the pressure change slopes of the train pipe, auxiliary reservoir, buffer cylinder, and brake cylinder: X L [(L2 - L1) / (T2 - T1)], X F [(F2 - F1) / (T2 - T1)], X J [(J2 - J1) / (T2 - T1)], X Z [(Z2 - Z1) / (T2 - T1)]; Determine the cause of the natural release failure based on the pressure change slopes: If X F is negative and X J、 remains unchanged, it indicates a leakage in the auxiliary reservoir pipe system. L 不变,则说明副风缸管系漏泄; 若X J、 X F、 X L 不变,X Z 为负值,则说明制动缸管系漏泄; 若X J 为负值,X L 为正值,X F 不变,则说明控制阀中加缓风缸与列车管之间的夹心阀漏泄; 若X L 为正值,X J、 X F、 不变,则说明不是铁路货车制动机故障。

[0018] Furthermore, when the train pipe, auxiliary reservoir, and buffer cylinder are charged to the first pressure and stabilized, a small reduction brake is applied and held at the second pressure, that is, the difference between the first pressure and the second pressure is not greater than 100 kPa, so that there are pressures in the train pipe, auxiliary reservoir, buffer cylinder, and brake cylinder.

[0019] Furthermore, it also includes a quick-connect plug, and the pressure sensor is installed through the quick-connect plug; one end of the quick-connect plug is provided with a first-size thread, which is consistent with the pressure sensor interface; the other end is provided with a second-size thread, which is consistent with the brake pipe system or the cone thread of the air cylinder, and the outer diameter of the second-size thread is smaller than the major diameter of the standard thread; a groove for placing an O-ring is provided on the joint surface of the quick-connect plug.

[0020] The beneficial effects of the present invention are as follows: (1) Without changing the configuration of the railway freight car brake, without disassembling the 120-type control valve, the pressure sensors corresponding to the train pipe, auxiliary air cylinder, acceleration and retardation air cylinder, and brake cylinder can be quickly installed in each pipeline. The data acquisition and processing equipment is used to read each pressure value, and based on this, the root cause of the natural release of the railway freight car brake is judged, so as to quickly check and troubleshoot the natural release fault.

[0021] (2) The present invention can quickly check and troubleshoot the natural release fault without borrowing other equipment, improving the fault troubleshooting efficiency; adopting a dual-power supply mode, it can meet the requirements of indoor and outdoor applications; a dedicated quick-connect plug is set, which ensures the quick installation and sealing reliability of the sensor, and also avoids the influence of foreign objects on the cleanliness of the pipe system. Description of the Drawings

[0022] Figure 1 Configuration diagram of the 120-type control valve.

[0023] Figure 2 Configuration diagram of the pressure sensor of the existing single car tester.

[0024] Figure 3 Normal brake small reduction braking curve diagram, where the curves L, F, J, and Z respectively represent the pressure values of the train pipe, auxiliary air cylinder, acceleration and retardation air cylinder, and brake cylinder.

[0025] Figure 4 Schematic diagram of the principle of the natural release fault troubleshooting device.

[0026] Figure 5 Schematic diagram of the structure of the quick-connect plug.

[0027] Figure 6 Assembly schematic diagram of the quick-connect plug. Specific Embodiments

[0028] For a clearer understanding of the technical features, objectives, and effects of the present invention, the specific embodiments of the present invention will now be described. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. That is, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0029] Embodiment 1 The natural release failure of the railway freight car brake is directly related to the pressures of the train pipe, auxiliary air cylinder, acceleration and release air cylinder, and brake cylinder. To determine the direct cause of the failure, it is necessary to simultaneously detect the pressures at four positions. The existing single-car tester only has the data of the pressure sensors of the train pipe and the brake cylinder, and can only judge that a natural release failure has occurred, but cannot determine the cause of the failure.

[0030] According to the operating principle of the 120-type control valve, it can be known that: (1) During charging and release, the train pipe, auxiliary air cylinder, and acceleration and release air cylinder are connected. Due to the large volume, even if there is a small leakage in each pipeline, the pressure gauge or sensor may not be able to detect it, and the brake cylinder pressure is zero, so the failure cannot be judged.

[0031] (2) During full braking or emergency braking, the auxiliary air cylinder is connected to the brake cylinder pipeline, and the volume increases, and natural release basically does not occur.

[0032] (3) During small reduction braking (not greater than 100 kPa) and holding pressure, there are pressures in the volumes of the train pipe, auxiliary air cylinder, acceleration and release air cylinder, and brake cylinder, and the pipelines of the acceleration and release air cylinder and the brake cylinder are completely independent. Although the train pipe and the auxiliary air cylinder are connected through a 0.2-mm backflow hole, due to the limitation of the hole diameter, the backflow volume is limited, and the leakage detection of the two can be carried out. Therefore, small reduction braking and holding pressure is the best time to detect the leakage of each pipe system, judge natural release, and release sensitivity.

[0033] Based on the above analysis, this embodiment provides a method for troubleshooting the natural release failure of a railway freight car brake, including: Data acquisition: Charge the train pipe, auxiliary air cylinder, and acceleration and release air cylinder of the railway freight car brake to the first pressure through a single-car tester or a locomotive brake. After stabilization, reduce the train pipe pressure to the second pressure and then hold the pressure; after the train pipe pressure is stable, read the pressure values of the train pipe, auxiliary air cylinder, acceleration and release air cylinder, and brake cylinder for the first time through a pressure sensor; wait for a period of time, and when the railway freight car brake has a natural release failure, that is, when the brake cylinder pressure suddenly drops, read the pressure values of the train pipe, auxiliary air cylinder, acceleration and release air cylinder, and brake cylinder for the second time through a pressure sensor; Fault Analysis: Based on the pressure changes of the train pipe, auxiliary air cylinder, retarder air cylinder and brake cylinder read in two consecutive readings, the cause of the natural release fault of the railway freight car brake is determined by the differential pressure troubleshooting method or the curve slope troubleshooting method.

[0034] Specifically, first, using a single-vehicle testing machine or locomotive brake machine, the train pipe, auxiliary air cylinder, and retarder air cylinder of the freight car brake are charged with air to a constant pressure (e.g., 500 kPa or 600 kPa). After stabilization, the train pipe is slightly depressurized (e.g., 50 kPa, or 40 kPa based on the brake sensitivity test) and then held at that pressure. Once the train pipe pressure stabilizes, the pressure values ​​of the train pipe, auxiliary air cylinder, retarder air cylinder, and brake cylinder are read for the first time. After waiting for a period of time, and after the vehicle brake experiences a natural release fault (brake cylinder pressure drops to 0), the pressure values ​​of the train pipe, auxiliary air cylinder, retarder air cylinder, and brake cylinder are read for the second time. During this process, the four pressure values ​​are saved in real time and plotted as curves, such as... Figure 3 As shown.

[0035] Preferably, the troubleshooting methods can be differential pressure troubleshooting and curve slope troubleshooting.

[0036] (1) Pressure difference investigation method By utilizing the pressure difference changes in the train pipe, auxiliary air cylinder, and retarder air cylinder, the cause of the natural relief fault can be determined, as shown in the table below.

[0037] Table 1 - Differential Pressure Troubleshooting Method for Identifying Natural Relief Faults

[0038] (2) Curve slope investigation method After the braking pressure stabilizes, the slope of the curves for the train pipe, auxiliary air cylinder, retarder air cylinder, and brake cylinder should be 0. When a natural release failure occurs, the brake cylinder pressure drops, and the slopes of the train pipe, auxiliary air cylinder, and retarder air cylinder will inevitably change.

[0039] At a certain moment T1 after the pressure stabilizes, read the pressure values ​​L1, F1, J1, and Z1 of the train pipe, auxiliary air cylinder, retarder cylinder, and brake cylinder. At the moment T2 when the brake cylinder suddenly drops, read the pressure values ​​L2, F2, J2, and Z2 of the train pipe, auxiliary air cylinder, retarder cylinder, and brake cylinder again, and calculate the pressure change slope X. L [(L2-L1) / (T2-T1)], X F [(F2-F1) / (T2-T1)], X J [(J2-J1) / (T2-T1)]、X Z [(Z2-Z1) / (T2-T1)], the cause of the natural mitigation fault can be determined by the following table.

[0040] Table 2 - Curve Slope Method for Identifying Natural Mitigation Faults

[0041] Example 2 This embodiment is based on embodiment 1: This embodiment provides a fault diagnosis device for the natural release of railway freight car brakes, such as... Figure 4 As shown, it mainly consists of quick-connect plugs, conduits, sensors, data acquisition and processing modules, a display screen, a battery, and an external power supply. It employs a dual power supply mode—both a battery and an external power source—to power the electrical components, enabling it to operate outdoors in conditions without power, thus meeting the requirements for troubleshooting railway freight cars outdoors.

[0042] The freight car brake system has taper thread plugs for drainage in the auxiliary air cylinder and the retarder air cylinder, and spare taper thread plugs are also provided in the train pipe and brake cylinder, but none of them have dedicated sensor interfaces. The connection between the taper threads is usually sealed with PTFE tape or sealant, but PTFE tape or sealant can easily enter the brake system piping, contaminating the cleanliness of the piping, potentially affecting the performance of the control valve, and ultimately affecting the vehicle's operational safety.

[0043] To improve troubleshooting efficiency, this embodiment features a dedicated quick-connect plug, enabling rapid sensor installation while ensuring reliable sealing. Preferably, as follows... Figure 5 and Figure 6 As shown, one end of the quick-connect plug is provided with a first-size thread, which is consistent with the pressure sensor interface; the other end is provided with a second-size thread, which is consistent with the brake piping system or the cylinder tapered thread, and the outer diameter of the second-size thread is smaller than the major diameter of the standard thread, so as to achieve the purpose of quick installation.

[0044] More preferably, the large end of the quick-connect plug is designed with an M20*1.5 thread to match the pressure sensor interface; the small end is designed with an R21 / 2 thread to match the brake piping or cylinder tapered thread, and the outer diameter of this external thread is smaller than the major diameter of the standard thread to achieve quick installation.

[0045] More preferably, the quick-connect plug has a groove on the mating surface for placing an O-ring for sealing, ensuring a good seal after installation.

[0046] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A method for troubleshooting the natural release fault of a railway freight car brake, characterized in that, include: Data Acquisition: Using a single-car tester or locomotive brake, the train pipe, auxiliary air cylinder, and retarder air cylinder of the railway freight car brake are pressurized to the first pressure. After stabilization, the train pipe pressure is reduced to the second pressure and then maintained. After the train pipe pressure stabilizes, the pressure values ​​of the train pipe, auxiliary air cylinder, retarder air cylinder, and brake cylinder are read for the first time using pressure sensors. After waiting for a period of time, when the railway freight car brake experiences a natural release failure, i.e., the brake cylinder pressure suddenly drops, the pressure values ​​of the train pipe, auxiliary air cylinder, retarder air cylinder, and brake cylinder are read for the second time using pressure sensors. Fault Analysis: Based on the pressure changes of the train pipe, auxiliary air cylinder, retarder air cylinder and brake cylinder read before and after, the cause of the natural release fault of the railway freight car brake is determined by the differential pressure troubleshooting method or the curve slope troubleshooting method. The differential pressure method can be used to determine the causes of spontaneous brake release failures in railway freight cars, including: If the pressure in the auxiliary air cylinder drops while the pressure in the deceleration air cylinder and the pressure in the train pipe remain unchanged, it indicates that the auxiliary air cylinder piping system is leaking. If the brake cylinder pressure drops while the train pipe, auxiliary air cylinder, and retarder air cylinder remain unchanged, it indicates a leak in the brake cylinder piping system. If the pressure of the retarder cylinder decreases, the pressure of the train pipe increases, and the pressure of the auxiliary cylinder remains unchanged, it indicates that the sandwich valve between the retarder cylinder and the train pipe in the control valve is leaking. If the train pipe pressure rises while the auxiliary air cylinder and the retarder air cylinder remain unchanged, it indicates that the problem is not with the railway freight car brake. The following are some of the reasons for the spontaneous release of railway freight car brakes, which can be determined using the curve slope troubleshooting method: Record the pressure values ​​of the train pipe, auxiliary air cylinder, retarder air cylinder and brake cylinder read for the first time as L1, F1, J1 and Z1 respectively, and record the time T1; Record the pressure values ​​of the train pipe, auxiliary air cylinder, retarder air cylinder and brake cylinder read for the second time as L2, F2, J2 and Z2 respectively, and record the time T2; Calculate the slope of pressure change in the train pipe, auxiliary air cylinder, retarder air cylinder, and brake cylinder: X L [(L2-L1) / (T2-T1)], X F [(F2-F1) / (T2-T1)], X J [(J2-J1) / (T2-T1)]、X Z [(Z2-Z1) / (T2-T1)]; Determine the cause of the natural relief failure based on the slope of the pressure change: If X F If X is negative, J、 X L If it remains unchanged, it indicates a leak in the auxiliary air cylinder piping system; If X J、 X F、 X L Unchanged, X Z A negative value indicates a leak in the brake cylinder piping system; If X J If X is negative, L X is a positive value. F If it remains unchanged, it indicates that the sandwich valve between the slow-release cylinder and the train pipe in the control valve is leaking; If X L X is a positive value. J、 X F、 If the result remains unchanged, it indicates that the problem is not with the railway freight car brake.

2. The method for troubleshooting the natural release fault of a railway freight car brake according to claim 1, characterized in that, After the train pipe, auxiliary air cylinder, and retarder air cylinder are filled with air to the first pressure and stabilized, a small pressure reduction braking is performed and the pressure is maintained to the second pressure, that is, the difference between the first pressure and the second pressure is not greater than 100 kPa, so that the train pipe, auxiliary air cylinder, retarder air cylinder and brake cylinder all have pressure.

3. The method for troubleshooting the natural release fault of a railway freight car brake according to claim 1, characterized in that, The pressure sensor is installed via a quick-connect plug. One end of the quick-connect plug is provided with a first-size thread, consistent with the pressure sensor interface; the other end is provided with a second-size thread, consistent with the brake piping system or air cylinder tapered thread, and the outer diameter of the second-size thread is smaller than the major diameter of the standard thread; the mating surface of the quick-connect plug is provided with a groove for placing an O-ring seal.

4. A fault diagnosis device for the natural release of railway freight car brakes, characterized in that, include: The data acquisition module, after the train pipe, auxiliary air cylinder, and retarder air cylinder of the railway freight car brake are charged to the first pressure by the single-vehicle tester or locomotive brake machine, and the pressure is reduced to the second pressure and then held and stabilized, reads the pressure values ​​of the train pipe, auxiliary air cylinder, retarder air cylinder, and brake cylinder for the first time through the pressure sensor; after waiting for a period of time, when the railway freight car brake experiences a natural release failure, i.e. the brake cylinder pressure suddenly drops, the data acquisition module reads the pressure values ​​of the train pipe, auxiliary air cylinder, retarder air cylinder, and brake cylinder for the second time through the pressure sensor; The data processing module is configured to determine the cause of the natural release fault of the railway freight car brake by using the pressure difference investigation method or the curve slope investigation method based on the pressure value changes of the train pipe, auxiliary air cylinder, retarding air cylinder and brake cylinder read before and after. The data processing module uses differential pressure troubleshooting to determine the causes of spontaneous brake release faults in railway freight cars, including: If the pressure in the auxiliary air cylinder drops while the pressure in the deceleration air cylinder and the pressure in the train pipe remain unchanged, it indicates that the auxiliary air cylinder piping system is leaking. If the brake cylinder pressure drops while the train pipe, auxiliary air cylinder, and retarder air cylinder remain unchanged, it indicates a leak in the brake cylinder piping system. If the pressure of the retarder cylinder decreases, the pressure of the train pipe increases, and the pressure of the auxiliary cylinder remains unchanged, it indicates that the sandwich valve between the retarder cylinder and the train pipe in the control valve is leaking. If the train pipe pressure rises while the auxiliary air cylinder and the retarder air cylinder remain unchanged, it indicates that the problem is not with the railway freight car brake. The data processing module uses the curve slope troubleshooting method to determine the causes of natural brake release failures in railway freight cars, including: Record the pressure values ​​of the train pipe, auxiliary air cylinder, retarder air cylinder and brake cylinder read for the first time as L1, F1, J1 and Z1 respectively, and record the time T1; Record the pressure values ​​of the train pipe, auxiliary air cylinder, retarder air cylinder and brake cylinder read for the second time as L2, F2, J2 and Z2 respectively, and record the time T2; Calculate the slope of pressure change in the train pipe, auxiliary air cylinder, retarder air cylinder, and brake cylinder: X L [(L2-L1) / (T2-T1)], X F [(F2-F1) / (T2-T1)], X J [(J2-J1) / (T2-T1)]、X Z [(Z2-Z1) / (T2-T1)]; Determine the cause of the natural relief failure based on the slope of the pressure change: If X F If X is negative, J、 X L If it remains unchanged, it indicates a leak in the auxiliary air cylinder piping system; If X J、 X F、 X L Unchanged, X Z A negative value indicates a leak in the brake cylinder piping system; If X J If X is negative, L X is a positive value. F If it remains unchanged, it indicates that the sandwich valve between the slow-release cylinder and the train pipe in the control valve is leaking; If X L X is a positive value. J、 X F、 If the result remains unchanged, it indicates that the problem is not with the railway freight car brake.

5. A fault diagnosis device for the natural release of railway freight car brakes according to claim 4, characterized in that, After the train pipe, auxiliary air cylinder, and retarder air cylinder are filled with air to the first pressure and stabilized, a small pressure reduction braking is performed and the pressure is maintained to the second pressure, that is, the difference between the first pressure and the second pressure is not greater than 100 kPa, so that the train pipe, auxiliary air cylinder, retarder air cylinder and brake cylinder all have pressure.

6. A fault diagnosis device for the natural release of railway freight car brakes according to claim 4, characterized in that, It also includes a quick-connect plug, through which the pressure sensor is installed; one end of the quick-connect plug is provided with a first-size thread, consistent with the pressure sensor interface; the other end is provided with a second-size thread, consistent with the brake piping system or air cylinder tapered thread, and the outer diameter of the second-size thread is smaller than the major diameter of the standard thread; the mating surface of the quick-connect plug is provided with a groove for placing an O-ring seal.

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