A vehicle-mounted anti-derailment lateral limiting device and its early warning system

Abstract

This invention provides a vehicle-mounted anti-derailment lateral limiting device and its early warning system. The invention determines the design concept of the anti-derailment limiting device by analyzing the wheel-rail contact geometry during derailment. To avoid interference between the device and the rail during train operation and to ensure its effective limitation of lateral displacement when the wheelset lifts, unique designs were made for the device's structure and installation dimensions in the lateral, longitudinal, and vertical directions. After the vehicle is equipped with the lateral limiting device of this invention, the critical derailment speed is increased, and the limiting device can better prevent vehicle derailment.

Description

Technical Field

[0001] This invention relates to the field of rail transit, and in particular to a vehicle-mounted anti-derailment lateral limiting device and its early warning system. Background Technology

[0002] High-speed train derailments are extremely dangerous. Even if derailment accidents cannot be completely eliminated, every effort should be made to prevent them or minimize the losses caused. This includes regularly conducting comprehensive and detailed inspections of vehicles and tracks, monitoring train operation in real time, providing early warnings of potential problems, closely monitoring weather conditions and the natural environment, suspending train services during severe weather and resuming operation only after the danger has been eliminated, and optimizing electrical systems, braking systems, and wheel-rail treads to improve the safety of the train itself. In addition to these methods, reliable and effective derailment prevention devices are also essential.

[0003] Anti-derailment devices can limit wheel slippage onto the rails in emergencies, keeping the wheelset on the rails even under external forces. Even if derailment is not prevented, they can prevent complete detachment from the rails for a short period, buying time for emergency braking and reducing the significant damage to passengers, goods, and surrounding personnel and buildings caused by high-speed derailment. Therefore, designing new anti-derailment devices, studying their effects during train derailment, and demonstrating their reliability are of great and positive significance for ensuring train safety.

[0004] In summary, due to the suddenness and complexity of high-speed train derailments, it is difficult to unify derailment criteria, making it challenging to effectively integrate various sensor detection methods with mechanical protective devices. To further improve railway transportation safety and reduce the potential risk of derailment, this invention aims to design a train derailment prevention and limiting device through theoretical analysis, optimization design, and numerical simulation. Addressing the limitations of current derailment protection devices, this invention designs a low-cost, easy-to-install, and highly reliable derailment prevention and limiting device. The device's operation process is simulated to verify its effectiveness. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention proposes a novel derailment protection approach and designs an on-board anti-derailment lateral limiting device and its early warning system. The design concept of the anti-derailment limiting device is determined by analyzing the wheel-rail contact geometry during derailment. To avoid interference between the device and the rail during train operation and to ensure its effective limitation of lateral displacement when the wheelset lifts, unique designs were implemented for the device's structure and installation dimensions in the lateral, longitudinal, and vertical directions. Specifically, this invention adopts the following technical solution:

[0006] A vehicle-mounted anti-derailment lateral limiting device includes a limiting plate, a limiting frame, a sensor, and a sensor fixing bracket.

[0007] The limiting plate is installed on the bogie of the front wheelset of the train, and includes a first connecting part, a support transition part, a second connecting part, and a rail contact part.

[0008] The first connecting part is connected to the train bogie, the limiting frame is installed on the supporting transition part, and the sensor is installed in the limiting frame through the sensor fixing support;

[0009] The support transition section is generally arc-shaped. The first connecting part and the second connecting part are respectively disposed at both ends of the support transition section. The first connecting part, the support transition section, and the second connecting part are integrally formed and are approximately located in the same plane.

[0010] The second connecting part is connected to the rail contact part, and the first connecting part and the second connecting part are substantially parallel and opposite in direction;

[0011] The rail contact portion includes a transverse force-bearing plate connected to the second connecting portion, and a rail action portion that comes into contact with the steel. The transverse force-bearing plate is perpendicular to the plane formed by the first connecting portion, the support transition portion, and the second connecting portion. The transverse force-bearing plate forms an acute angle with the plane where the rail is located.

[0012] One end of the transverse force plate is connected to the second connecting part, and the other end is connected to the rail action part, which is perpendicular to the plane of the rail.

[0013] Preferably, the thickness of the limiting plate is 10-19mm, and the vertical dimension below the rail surface is 35-45mm.

[0014] This invention also provides an early warning system for a vehicle-mounted anti-derailment lateral limiting device.

[0015] The system includes a pressure detection unit and an early warning unit;

[0016] The pressure detection unit monitors the pressure on the limit plate, collects signals to generate voltage, and compares it with a set reference voltage. When the voltage exceeds the reference voltage, the detection unit outputs a warning signal, indicating that the derailment limit device has started working. The warning unit starts timing, and when the timing reaches t seconds, the detected voltage decreases below the reference voltage, the timing stops, the pressure detection unit stops outputting signals, and the alarm is cleared. When the time exceeds t seconds and the detected voltage is still greater than the reference voltage, it indicates that the device has reached its working limit, and the wheelset has not returned to the centering position within t time after acting on the rail. At this time, the warning unit issues an emergency braking signal. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the wheel derailment process.

[0018] Figure 2 This is a diagram showing the relative positions of the limit plate and the bogie.

[0019] Figure 3 This is a schematic diagram of wheelsets passing through frogs and guard rails.

[0020] Figure 4 It is a drawing showing the shape and dimensions of the wheel flange tread.

[0021] Figure 5 This is a diagram showing the lateral dimension range of the limiting plate.

[0022] Figure 6 This is a geometric diagram of the bogie when it is cornering.

[0023] Figure 7 This is the assembly diagram for the anti-derailment limit device.

[0024] Figure 8 This is a schematic diagram showing the relative position and function of the limiting device and the track.

[0025] Figure 9 This is a schematic diagram of the bogie and its limiting device.

[0026] Figure 10 This is a block diagram illustrating the working principle of a derailment early warning system.

[0027] Figure 11 This is the circuit diagram of a derailment early warning system.

[0028] Figure 12 This is the hardware circuit diagram of the limit device derailment early warning system.

[0029] Figure 13 This is a diagram illustrating the method for determining the critical speed of a vehicle after a warning.

[0030] Figure 14 This is a diagram illustrating the process of a wheel derailing from the outer rail.

[0031] Figure 15 Lateral force diagram of wheel-rail on the outer rail side of the front bogie.

[0032] Figure 16 Relative displacement diagram of wheel and rail on the outer rail side of the front bogie.

[0033] Among them, 1-limiting device, 2-first connecting part, 3-support transition part, 4-sensor and fixed support, 5-limiting frame, 6-transverse force-bearing plate, 7-rail working part, 8-second connecting part Detailed Implementation

[0034] 1. Working principle of anti-derailment device

[0035] The most direct way to determine if a wheel has derailed is to observe the geometry of the wheel-rail contact and determine whether derailment has occurred based on the amount of wheel lift. During derailment, the relative positions of the wheel and rail are as follows: Figure 1 As shown in the figure, the vertical distance h between the nominal contact point of the wheel tread and the highest point of the rail top is... p h is the amount of wheel lift. i h is the rim height. j For the jump height, l w This represents the lateral displacement of the wheelset.

[0036] Figure 1 a) is a schematic diagram of the wheel's rail climbing process. When the bottom of the wheel flange has completely climbed onto the rail, h p =h i And the lateral displacement of the wheelset l w When a certain value is reached, it can be determined that the wheel has detached from the rail. Figure 1 b) is a schematic diagram of the wheel jumping off the rail and derailing process. The wheel jumps off the rail instantaneously from its normal operating state. At this time, h p =h j When the wheel is in a suspended state, if there is no lateral movement, the wheel and rail will quickly return to normal contact. However, if the wheel is subjected to even a slight lateral disturbance, it will detach from the rail.

[0037] Therefore, it can be seen that lateral movement of the wheelset is a necessary condition for the wheel to derail. To prevent derailment, this can be addressed by limiting the large-scale lateral relative movement between the wheelset and the rail. Thus, the derailment prevention limiting device designed in this invention works by temporarily limiting the lateral movement of the wheelset when it climbs or jumps onto the top of the rail, preventing the train from derailing for a short period. Then, through automatic wheelset alignment, the train resumes operation.

[0038] 2. Design requirements for anti-derailment devices

[0039] The structure in the anti-derailment device that interacts with the rail is called the limiting plate. Figure 2 This diagram illustrates the relative positional relationship between the bottom of the limit plate and the bogie during derailment. The solid line represents the wheel flange outline circle, and the dashed line represents the wheel rolling circle. When a single wheel of the bogie lifts, as... Figure 2 As shown in a), the centerlines of the two wheels will rotate relative to each other around the wheel-rail contact point of the wheel that is not lifted, with a rotation angle of σ. The device mounted at the bottom of the bogie will also rotate at a certain angle. When the front and rear wheels on the same side are lifted simultaneously, the relative positions of the wheel and rail are shown in Figure a). Figure 2 b) The anti-derailment device moves upwards as a whole. The relevant dimensions of the limit plate are a, b, and L. w These represent the following dimensions: the width of the limiting plate, the vertical dimension of the limiting plate rail surface, and the center distance between the limiting plate and the front wheel pair; L is the bogie wheelbase, R is the wheel rolling circle diameter, and h is the wheel diameter.r and h f These represent the rail height and the vertical distance between the highest point of the rail fastener and the top of the rail. Based on the relative position of the anti-derailment device and the rail, the dimensional limits of the device during operation can be understood more intuitively.

[0040] In terms of structural dimensions design, in addition to considering whether the anti-derailment device can fully perform its limiting function, it is also necessary to pay attention to whether it will have unnecessary contact with the rail. Figure 3 A schematic diagram showing the derailment prevention device via frogs and guard rails. Figure 3 In the middle, D x For checking the spacing, D refers to the distance from the working surface of the frog to the outer side of the guard rail head. y The guard rail spacing refers to the distance from the working edge of the frog wing rail to the outer side of the guard rail head. h t1 is the width of the guard rail flange groove in the straight section, t2 is the depth of the frog flange groove, t2 is the width of the frog flange groove in the section with a frog width of 20 to 50 mm corresponding to the wing rail, and S m is the inner distance of the wheelset, and c is the width of the limiting plate.

[0041] When wheels pass over frogs and guardrails, they must meet the required inspection interval and guardrail clearance. Inspection interval D x The backrest spacing D should be no less than 1391mm. y The distance between the inner sides of the passenger vehicle wheelset and the center of gravity should be no less than 1348mm. m The maximum length is 1355mm.

[0042] Based on the above conditions, the specific structural design requirements for the anti-derailment device are as follows:

[0043] (1) When the wheelset climbs the rail or jumps off the rail within a certain height range, ensure that the bottom of the anti-derailment device remains below the rail surface so as to play its limiting role;

[0044] (2) The anti-derailment device will not collide with the rails and the fasteners on both sides of the rails during normal train operation;

[0045] (3) The anti-derailment device can pass smoothly through the turnout and guardrail without affecting the vehicle's curve passing performance.

[0046] 3. Anti-derailment device structure and installation dimension range

[0047] The dimensional range of the limiting device in three directions will be determined based on the relative position of the device and the rail. The longitudinal direction is the direction of vehicle travel; the direction perpendicular to the longitudinal direction within the track plane is the lateral direction; and the direction perpendicular to the track plane is the vertical direction.

[0048] 3.1 Vertical dimension range

[0049] According to design requirements, to ensure that the limiting plate remains below the rail top when the wheel is lifted, the vertical dimension b of the limiting device on the rail surface should be greater than the wheel flange height. The shape and dimensions of the tread flange of a high-speed train wear-type (LM) wheel flange are as follows: Figure 4 As shown, the rim height is 27mm.

[0050] Considering the descent of the device position due to wheel maintenance and tread wear, to prevent the anti-derailment device from colliding with the trackside infrastructure, the sum of the device's lower rail dimension b and the maximum tread wear depth should be less than the distance between the highest point of the track fastener and the rail top. Actual on-site measurements show that the distance h from the highest point of the trackside fastener to the rail top is... f Generally, it should not exceed 90mm. When running on standard rails, the maximum value of b should be less than 82mm. Furthermore, the anti-derailment device must not impact the bottom of the frog groove when the wheelset passes the frog, and the shallowest depth t of the point rail flange groove... 1min It is 48mm.

[0051] The vertical dimension b of the rail surface should be between 27mm and 48mm. Taking a value of b of 35-45mm can prevent the wheelset from climbing and derailing, and prevent the standard profile wheelset from jumping and derailing when the front and rear wheelsets are raised at the same time if the lifting height is less than 35-45mm.

[0052] 3.2 Lateral dimension range

[0053] Laterally, the limiting device must ensure it functions fully when the wheel flange climbs onto the rail, while also ensuring it doesn't interfere with normal vehicle operation. When the wheel reaches the derailment position, the minimum lateral displacement of the wheelset is the distance from the bottom of the wheel flange to the centerline of the rail top. During normal wheel-rail contact, the centerline of the rail top coincides with the wheel's rolling circle. Figure 4 It can be seen that the distance l from the bottom of the wheel rim to the rolling circle of the wheel is... w It is 54mm.

[0054] Figure 5 This illustrates the translation and rotation of the limiting device as the wheel flange climbs onto the rail, from which the lateral dimension range of the limiting plate can be deduced. The distance between the limiting device near the rail side and the bottom of the wheel flange is l. a The lateral deformation of the device due to the force is l b To meet the design requirements, l a With l b The sum of the lengths must not exceed 54mm.

[0055] When passing through a turnout, the inner distance of the limit plate should be greater than the back guard spacing D. y (1348mm), otherwise the device is easily jammed by the guard rail. Therefore, the inner distance of the wheelset and the inner distance of the limiting plate satisfy equation (1).

[0056] S m +32-2(c+la )>D y (1)

[0058] Calculations show that the thickness c of the limiting plate is related to the mounting dimension l relative to the bottom of the wheel rim. a The sum should be less than 19.5 mm.

[0059] Considering the impact of wheel set lateral movement, the thickness c of the limiting plate was finally determined to be 10-19mm.

[0060] 3.3 Range of longitudinal dimensions

[0061] The longitudinal dimensions of anti-derailment devices are limited by their lateral and vertical dimensions.

[0062] First, an excessively large longitudinal dimension of the anti-derailment device will affect the bogie's curve-passing performance. When the locomotive passes through a curve, the wheelset will impact the outer rail. The angle θ between the outer wheel plane of the first wheelset and the rail is called the angle of attack. The angle of attack can be approximately calculated, i.e., equation (2).

[0063]

[0064] In the formula, x is the center distance of the first wheel rotation, and R l The radius of the curve of the line.

[0065] Simplified geometric diagram of the bogie passing through a curve, as shown below. Figure 6 As shown, the dashed line represents the plane where the limiting plate is located, and the distance L between the limiting plate and the center of the front wheel set is... w Lateral installation dimension l of the device a The relationship should satisfy equation (3).

[0066]

[0067] Secondly, when the first wheelset is raised, it generates a certain rotation angle σ relative to the second wheelset in a plane perpendicular to the track, as referenced. Figure 2 a) The value of σ is approximated by equation (4).

[0068]

[0069] To prevent the limiting plate from failing to engage with the rail due to insufficient height when one wheelset is raised, the center distance L between the limiting plate and the front wheelset is [not specified]. w In addition to meeting the above requirements, the lateral installation dimension l of the device is also required. a The relationship should also satisfy equation (5).

[0070]

[0071] In addition, L w If the size is too small, it will cause the anti-derailment device to interfere with the wheel.

[0072] After comprehensive consideration, we choose L. w With a wheel-rail angle of attack of 450mm, the wheelset can smoothly pass through curves when the wheel-rail angle of attack is less than 0.127rad, and can prevent derailment and track skipping when a single wheelset lifts, with a standard profile wheelset lifting height of less than 27mm-35mm.

[0073] 3.4 Structure and installation location of anti-derailment device

[0074] Assembly drawing of anti-derailment limit device 1 is shown below. Figure 7 It includes the following components: a limiting plate, a limiting frame 5, a sensor and a sensor mounting bracket 4.

[0075] The limiting plate is installed on the bogie of the front wheelset of the train. It includes a first connecting part 2, a support transition part 3, a second connecting part 8, and a rail contact part. The first connecting part 2 is connected to the train bogie. The limiting frame 5 is installed on the support transition part 3. The sensor is installed in the limiting frame 5 through the sensor fixing support.

[0076] The support transition section 3 is generally arc-shaped. The first connecting part 2 and the second connecting part 8 are respectively located at both ends of the support transition section 3. The first connecting part 2, the support transition section 3, and the second connecting part 8 are integrally formed and are roughly located in the same plane. The second connecting part 8 is connected to the rail contact part. The first connecting part 2 and the second connecting part 8 are roughly parallel and opposite in direction.

[0077] The rail contact portion includes a transverse force-bearing plate 6 connected to the second connecting portion, and a rail action portion 7 that contacts the steel. The transverse force-bearing plate 6 is perpendicular to the plane formed by the first connecting portion 2, the support transition portion 3, and the second connecting portion 8, and forms an acute angle with the plane containing the rail. One end of the transverse force-bearing plate is connected to the second connecting portion, and the other end is connected to the rail action portion 7, which is perpendicular to the plane containing the rail.

[0078] The limiting plate is the main load-bearing component. When the limiting device 1 is activated, the force is transmitted from the rail through the limiting plate to the bogie. The limiting frame serves two purposes: first, it accommodates precision components such as sensors; second, when the limiting plate undergoes large deformation, the frame provides support, jointly bearing the lateral force. The sensor mounting bracket secures the sensor inside the limiting frame.

[0079] Based on the overall optimized design and implementation effect, the schematic diagram of the relative position and function of the limiting device 1 and the track is as follows: Figure 8 As shown.

[0080] The installation position of the anti-derailment device on the bogie is as follows: Figure 9As shown, a bogie has four limit devices installed. The limit plates are fixed to the bogie frame near the wheelset by welding, and the frame is fixed to the axle box rear cover by bolts. Springs, sensors, and other devices are installed inside the frame.

[0081] 4. Design of anti-derailment device early warning system

[0082] The derailment early warning system consists of two parts: a pressure detection unit and an early warning unit. The device is powered by a low-voltage DC power supply, and its operating procedure is as follows:

[0083] The anti-derailment limiting device interacts with the rail, causing deformation. A pressure sensor detects the pressure on the limiting plate, collects the signal to generate a voltage, and compares it with a set reference voltage. When the voltage exceeds the reference voltage V, the detection unit outputs a warning signal 1. This signal indicates that the derailment limiting device has started working, the train is experiencing an anomaly on this section of the track, and the train crew is prompted to take timely preventative measures. Simultaneously, the warning unit starts timing. When time t seconds have elapsed and the voltage decreases below V, the timing stops, the detection unit stops outputting signals, and the alarm is cleared. If time exceeds t seconds and the detected voltage is still greater than V, it indicates that the device has reached its working limit, and the wheelset has not returned to its centered position within t time after acting on the rail. At this point, an emergency braking signal is issued to prevent further derailment. Its working principle is as follows: Figure 10 As shown.

[0084] The circuit diagram of the derailment early warning system is as follows: Figure 11 As shown, the system circuit mainly consists of four parts: a pressure threshold switch, a voltage amplifier, a pulse generation circuit, and a monostable multivibrator. The pressure threshold switch is composed of a Wheatstone bridge and a voltage comparator. R1 is a variable resistor; adjusting the value of R1 controls the magnitude of the reference voltage. When the pressure sensor detects an increase in force, its resistance R2 decreases. When R2 is less than R1, the switch outputs a high level, providing a trigger signal for subsequent devices.

[0085] The trigger signal is output as a voltage, and its output power is amplified by a differential amplifier. Once the trigger signal is generated, a train operation anomaly warning is issued. Simultaneously, the pulse circuit level jumps from 0 to 1, the capacitor discharges for one cycle and then cuts off, and the level gradually returns to 0. This pulse signal passes through an NOT gate, triggering a monostable multivibrator composed of a 555 timer that is triggered by a low-level trigger. The output pulse signal returns to zero after t seconds, passes through an NOT gate, and is set to 1. If the pressure threshold switch is open at this time, i.e., the input voltage is still higher than the reference voltage V, an emergency braking signal for the train is issued.

[0086] The hardware circuit of the limit switch derailment early warning system includes: a 555 timer chip, an LM324 chip, a 74LS00 chip, resistors, diodes, transistors, and capacitors. The circuit wiring diagram is shown below. Figure 12 As shown.

[0087] The 555 timer circuit, with its external capacitors and resistors, forms a monostable multivibrator used for timing. When an irregular waveform trigger pulse is received at the input, the multivibrator outputs a rectangular pulse, the pulse width of which is the duration T of the quasi-stable state. p That is, the timing period. T p The calculation formula is as follows:

[0088] T p =1.1RC (6)

[0090] Changing the RC value can alter the pulse width, thereby enabling ideal timing control.

[0091] The LM339 is a quad operational amplifier IC containing four independent operational amplifiers powered by a common power supply. In this circuit, only two are used. One comparator, connected to an external resistor, forms a differential amplifier, drawing power from the power supply to enhance the output signal power. The other comparator compares the input voltage with a reference voltage to determine the type of the output signal. The 74LS00 contains four sets of 2-input NAND gates (positive logic). By controlling the connection of the NAND gate's input and output terminals, two NOT gates and one AND gate can be formed.

[0092] 5. Experimental verification

[0093] 5.1 Critical speed for vehicle derailment

[0094] The method for determining the critical derailment speed of a vehicle equipped with a limit device is as follows: Figure 13 As shown, v1 represents the critical derailment speed of a vehicle without a limit device. When the vehicle enters a curved section at a speed exceeding this, emergency braking is activated upon detecting lateral force on the device, simulating the device's warning function. The average emergency braking acceleration is selected as 0.914 m / s² when the initial braking speed is between 200 and 300 km / h. 2 Take the braking acceleration of the train as 1 m / s² 2 The limiting plate thickness is set to 15mm, and the vertical dimension of the rail surface is 40mm. The vehicle's speed as it enters the curve is continuously increased, and its ability to brake smoothly after a warning is issued is observed. The critical derailment speed v2 is then determined.

[0095] Based on the above calculations, Table 1 shows the critical derailment speeds of vehicles with and without lateral limit devices on three lines with curve radii of 800m, 1000m, and 1200m. It can be seen that the larger the curve radius, the higher the critical derailment speed. After installing the lateral limit device, the critical derailment speeds of all vehicles increased, indicating that the limit device is more effective in preventing derailment. At a curve radius of 800m, the difference in critical derailment speed before and after installing the limit device is approximately 16.2 km / h; at a curve radius of 1200m, the difference is approximately 23.8 km / h. This demonstrates that the larger the curve radius, the wider the range of derailment speeds the device can limit, and the better its derailment prevention effect.

[0096] Table 1 Critical Derailment Speed ​​of Vehicles

[0097]

[0098] 5.2 Lateral force on the limiting plate

[0099] The front bogie of a vehicle always enters the curve first. When derailing, the first and second wheelsets are the first to impact the rail. Therefore, this invention mainly focuses on the research of the front bogie of a vehicle.

[0100] The vehicle was traveling at the critical derailment speed on curves with radii of 800m, 1000m, and 1200m. On the 1200m radius curve, due to the highest speed, the vehicle entered the curve first, and the stop plate acted on the rails at approximately 2.2s. On the 800m radius curve, the stop plate acted on the rails at approximately 2.7s. While the contact time between the stop plate and the rails was relatively short, on the 800m radius curve, due to the slower vehicle speed, the stop plate's contact time was relatively longer, resulting in an impact of approximately 0.5s. Afterward, as the wheel flanges resumed their guiding function, the force on the device rapidly decreased to zero.

[0101] The maximum lateral force on the limiting plate is approximately 25.0 kN when the curve radius is 800 m, approximately 22.7 kN when the radius is 1000 m, and approximately 18.2 kN when the radius is 1200 m. Therefore, it can be seen that the smaller the curve radius, the greater the lateral force on the limiting plate.

[0102] 5.3 Wheel-rail force and contact patch variation

[0103] According to simulation results, the trends of wheel-rail lateral and vertical forces during derailment at curve radii of 800m, 1000m, and 1200m are consistent. The changes in wheel-rail lateral and vertical forces and wheel-rail contact patches on the outer rail side of the vehicle's first wheel during derailment are also observed. Figure 14 .

[0104] Figure 14 Section a) represents the vehicle's operation on a straight section, with the contact patch resting on the rail top in an elliptical shape. Sections b)-d) represent the stable operating sections of the vehicle on transition curves and circular curves. As the vehicle enters the transition curve, the wheel-rail interaction force increases rapidly, and the contact patch moves to the right, as shown in b). At time c), the wheel flange root begins to contact the rail, and the lateral and vertical forces increase slowly until a relatively stable state is reached, i.e., d). At this point, the wheel flange root is tightly pressed against the rail surface, and the relative wheel-rail position is at the traditional quasi-static derailment critical position. The vehicle continues to run on the curve, and the vehicle's center of gravity continuously shifts towards the outer rail side until... Figure 14 In section e), the contact patch is divided into two, and the tread and wheel flange simultaneously contact the rail. The wheel flange loses its lateral restraint function, and the lateral force decreases rapidly. At this time, the wheel-rail contact state is extremely unstable. Finally, the tread leaves the rail, and the wheel flange climbs onto the top of the rail, as shown in (f). The vertical force between the wheel and rail decreases rapidly until the wheelset completely detaches from the rail.

[0105] Before and after the installation of the anti-derailment device, when the vehicle is running on a track with a radius of 1000m, the lateral force between the wheel and rail of one wheelset is as follows: Figure 15 As shown, upon entering the transition curve, the rapid lateral speed of the wheelset causes a significant increase in lateral force within a short period. Due to the vehicle's unstable operation, the lateral force fluctuates between 40-70 kN. The circled area in the figure corresponds to the section where the anti-derailment device is effective. It can be seen that the lateral force of the wheelset without the device drops from 60 kN to 0 after the last fluctuation. When the wheelset is close to derailment, the device bears nearly one-third of the lateral force on the wheel flange, interfering with the derailment process. After exiting the curve, the lateral force decreases rapidly.

[0106] 5.4 Wheel-rail relative displacement

[0107] Through comparison, it was found that the derailment prevention lateral limit device has a similar function when the vehicle derails on curves with different radii. This invention analyzes the wheel-rail relative displacement before and after the installation of the derailment prevention device when the vehicle is running at the critical derailment speed on a curve with a radius of 1000m.

[0108] Before and after the installation of the lateral limiting device, the lateral displacement and lifting of the wheels on the outer rail side of the front bogie are as follows: Figure 16 As shown. Wheel displacement data of vehicles without anti-derailment devices are represented by dashed lines, while vehicles with anti-derailment devices at the same speed are represented by solid lines. At approximately 1.3 seconds, the vehicle enters the curve, and the wheel lateral displacement increases to 5mm. At this point, the wheel flange root is in contact with the rail. After 2 seconds, both the lateral displacement and the lifting increase simultaneously, indicating that the wheel flange begins to climb onto the rail. At approximately 3 seconds, the lifting of the wheel without a limit device reaches its maximum value of 27mm, equal to the flange height, and then rapidly decreases. At this point, the wheel lateral displacement increases rapidly, indicating that the wheel has derailed. The second wheel subsequently derails.

[0109] For vehicles equipped with limit devices, when the lateral displacement is around 10mm and the lifting has not reached its maximum point, the outer wheel on the rail side does not continue to move outward through contact with the device. Instead, the wheel flange regains its guiding function through automatic centering. After about 3.5 seconds, the vehicle exits the curve, the wheels fall, and the tread contacts the top of the rail. Due to the tendency of the vehicle to roll, the wheelset and the rail will maintain relative movement in the lateral direction for a period of time until the operation is completely stable.

[0110] This invention addresses vehicle derailment caused by speeding on small-radius curves. It simulates scenarios before and after the installation of an anti-derailment device, with vehicles traveling at 40 m / s on a track with EI Centro seismic wave input, and at critical derailment speeds on curves with radii of 800 m, 1000 m, and 1200 m. The study investigates the effect of the anti-derailment device under these different derailment conditions. Dynamic simulations yield calculations of wheel-rail relative displacement, wheel-rail contact force, and the force between the device and the rail. Simulation results demonstrate that the anti-derailment device effectively prevents derailment by limiting lateral wheel displacement, and on curves with larger radii, the device's anti-derailment effect is better.

Claims

1. A vehicle-mounted derailment-preventing lateral limiting device, comprising a limiting plate, a limiting frame, a sensor, and a sensor fixing support, characterized in that the limiting plate is mounted on a bogie of a front wheel pair of a train, and comprises a first connecting part, a supporting transition part, a second connecting part, and a rail contact part; the first connecting part is connected with the bogie of the train, the limiting frame is mounted on the supporting transition part, and the sensor is mounted in the limiting frame through the sensor fixing support; the supporting transition part is in the shape of an arc segment as a whole, the first connecting part and the second connecting part are respectively arranged at two ends of the supporting transition part, the first connecting part, the supporting transition part, and the second connecting part are integrally formed and located in substantially the same plane; the second connecting part is connected with the rail contact part, and the first connecting part and the second connecting part are substantially parallel and opposite in direction; the rail contact part comprises a lateral force receiving plate connected with the second connecting part, and a rail acting part for contacting with a steel rail, the lateral force receiving plate is perpendicular to the plane formed by the first connecting part, the supporting transition part, and the second connecting part, and forms an acute angle with the plane on which the rail is located; one end of the lateral force receiving plate is connected with the second connecting part, and the other end is connected with the rail acting part, and the rail acting part is perpendicular to the plane on which the rail is located.

2. The vehicle-mounted derailment-preventing lateral limiting device according to claim 1, characterized in that the thickness of the limiting plate is 10-19 mm, and the vertical dimension below the rail surface is 35-45 mm.

3. A pre-warning system applied to the vehicle-mounted derailment-preventing lateral limiting device according to claim 1, characterized in that the system comprises a pressure detection unit and a pre-warning unit; the pressure detection unit detects that the limiting plate bears pressure, collects signals to generate a voltage, and compares the voltage with a set reference voltage, when the voltage exceeds the reference voltage, the detection unit outputs a pre-warning signal, the pre-warning signal indicates that the derailment limiting device starts to work, the pre-warning unit starts timing, when the timing time reaches t seconds, the detection voltage decreases to below the reference voltage, the timing stops, the pressure detection unit stops outputting signals, and the alarm is released; when the time exceeds t seconds, and the detection voltage is still greater than the reference voltage, it indicates that the device has reached the working limit, and the wheel pair has not returned to the centered position within t time after acting on the rail, the pre-warning unit at this time sends an emergency braking signal. ​ ​ ​

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