Track load detection method

Abstract

This invention discloses a track load detection method, belonging to the field of rail transit. The rails on both sides of the detection area are detected using the same method. For one side of the rail, two detection positions are set on the web of a section of rail within every two adjacent sleepers, and a shear force sensor is installed at each detection position. A bridge is formed between the shear force sensors at the Nth and N+1th detection positions, and another bridge is formed between the Nth and N+3th detection positions. Each shear force sensor is connected to a processor. A specific data processing scheme of this invention is applied to obtain the precise weight of the vehicle. This invention does not use weighing sensors, has a simple structure, is easy to install, and requires no modification to existing roadbeds, sleepers, or fasteners. It can accomplish projects that are difficult to complete with existing technologies, such as high-speed rail and subways, which are sensitive to modifications and have time constraints, reducing construction time, costs, and safety hazards.

Description

Technical Field

[0001] This invention relates to the field of rail transit, and in particular to a method for detecting track load. Background Technology

[0002] The interaction between wheels and rails directly affects railway traffic safety, wheel and rail wear, and maintenance. Currently, a large number of non-derailed rails have been installed in the domestic railway, subway, and urban rail transit industries. The interaction force between wheels and non-derailed rails is measured by rail weighing devices.

[0003] Specifically, shear force sensors installed on the rails mechanically separate the detection zone from the track. Load cells are then placed within the detection zone in conjunction with the shear force sensors to eliminate the mechanical influence of the track passing over the rails, thus completing the weighing process. However, this method requires two sensors to work together, especially the load cells, whose elastic bodies require a certain amount of installation space, thus limiting their overall dimensions.

[0004] The installation of weighing sensors requires modification of existing sleepers, track beds, or fasteners. This involves a large workload, complex processes (such as breaking up existing structures and pouring new ones), and a long cycle, leading to safety hazards during construction and operation. This makes this detection method unsuitable for applications such as high-speed rail lines, bullet train lines, and subway lines. In these situations, if the existing structure needs modification, the maintenance window (the time available for track work) is short; for example, subways typically have a 3-hour maintenance window per day, while the maintenance window for high-speed rail is unpredictable. Summary of the Invention

[0005] This invention provides a track load detection method that is simple in structure, easy to install, and reduces construction time, cost, and safety hazards caused by construction.

[0006] The technical solution provided by this invention is as follows:

[0007] A method for detecting rail load, wherein rails on both sides of a detection zone are detected using the same method, the method comprising:

[0008] For the rails on one side of the detection area, two detection positions are set on the web of a section of rail within every two adjacent sleepers. Each detection position is equipped with a shear force sensor, and each shear force sensor is connected to the processor. According to the order of the detection positions, the shear force sensors of the Nth detection position are bridged with those of the (N+1)th detection position, and the shear force sensors of the Nth detection position are bridged with those of the (N+3)th detection position, where N = 1, 3, 5, 7, ...

[0009] For one side of the rail, the processor acquires the waveforms of the shear force sensors at each detection position when the wheel passes through the detection zone. The horizontal axis of the waveform is time, and the vertical axis is the output value of the shear force sensor.

[0010] The waveforms of the shear force sensors at the Nth and (N+3)th detection positions are added together to obtain the composite waveform.

[0011] Using the horizontal axis as a reference, the various synthesized waveforms are displayed in chronological order on the same coordinate system to obtain a waveform curve.

[0012] Based on the waveform curve, the top flat portion of each synthesized waveform is fitted into a straight line, and the load force is determined according to the fitted straight line to complete the weighing.

[0013] Furthermore, the detection area is located on a straight section of the rail, the length of the detection area is greater than the circumference of the wheel, the distance between the detection position closest to the sleeper and the sleeper is not less than half the height of the rail, and the distance between two adjacent detection positions within two adjacent sleepers is 200-300mm.

[0014] Furthermore, two shear sensors are provided at each detection position, and the two shear sensors at the same detection position are symmetrically installed on both sides of the detection position of the rail web.

[0015] Furthermore, the shear force sensor is mounted on the web of the rail via a mounting bracket, wherein:

[0016] The mounting bracket includes two symmetrical bracket units, which are symmetrically arranged on both sides of the rail. The upper part of each bracket unit is pressed against the rail web side by a first set of bolts, and the lower parts of the two bracket units are connected and fastened together by a second set of bolts.

[0017] Furthermore, the support unit includes a sensor mounting part and a support unit connecting part. The sensor mounting part is located at a set distance outside the rail web of the rail, and the support unit connecting part is located below the sensor mounting part. The support unit connecting part extends from the bottom of the rail towards the inside of the rail.

[0018] The shear force sensor is pressed against the rail web side of the rail by the first set of bolts on the sensor mounting part of each support unit, and the support unit connecting parts of two support units are connected and fastened together by the second set of bolts.

[0019] Furthermore, a disc spring washer is provided between the first set of bolts and the shear force sensor, and a protective cover is provided outside the mounting bracket.

[0020] Furthermore, the shape of the lower inner side of the support unit corresponds to the shape of the lower part of the rail.

[0021] The present invention has the following beneficial effects:

[0022] Compared with existing technologies, this invention does not use weighing sensors. Instead, it only requires the installation of shear force sensors on the rail between every two sleepers within the detection zone, preferably in the middle of the rail web. Two sets of shear force sensors are installed between adjacent sleepers. The shear force sensors are continuously arranged to obtain the required detection zone length. By continuously setting up the shear force sensors and implementing the specific bridge assembly and data processing scheme of this invention, the precise weight of the vehicle can be obtained.

[0023] This invention does not use weighing sensors, has a simple structure, is easy to install, and does not require modification of existing roadbeds, sleepers, or fasteners. It can complete projects that cannot be completed by existing technologies, such as high-speed rail and subways, which are sensitive to modification and have limited construction time (short maintenance windows, usually 3 hours per day), thus reducing construction time, cost, and safety hazards caused by construction. Attached Figure Description

[0024] Figure 1 This is a side view of the structure corresponding to the track load detection method of the present invention;

[0025] Figure 2 This is a top view of the structure corresponding to the track load detection method of the present invention;

[0026] Figure 3 This is a schematic diagram of a shear force sensor bridge assembly.

[0027] Figure 4 This is a cross-sectional view of the shear force sensor installation.

[0028] Figure 5 Side view showing the installation of the shear force sensor;

[0029] Figure 6 Example waveform diagram of the shear force sensor at the first detection position;

[0030] Figure 7 Example waveform diagram of the shear force sensor at the 4th detection position;

[0031] Figure 8 for Figure 6 and Figure 7 Example of the combined waveform after addition;

[0032] Figure 9 A waveform graph composed of various synthesized waveforms;

[0033] Figure 10 A schematic diagram of the waveform curve after linear fitting;

[0034] Figure 11 A schematic diagram of the waveform curve after curve fitting;

[0035] Figure 12The fitted curve corresponding to the wheel flat scar defect;

[0036] Figure 13 This is the fitted curve corresponding to the polygonal defect on the wheel. Detailed Implementation

[0037] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0038] This invention provides a method for detecting track load, such as... Figure 1-5 As shown, the rails 1 on both sides of the inspection area are inspected using the same method, which includes:

[0039] S1: For the rail 1 on one side of the detection area, two detection positions 5 are set on the web 4 of a section of rail 1 within every two adjacent sleepers 2. Each detection position 5 is equipped with a shear force sensor 3, and each shear force sensor 3 is connected to the processor. According to the order of the detection positions 5, the shear force sensor 3 of the Nth detection position 5 is bridged with the shear force sensor 3 of the N+1th detection position 5, and the shear force sensor 3 of the Nth detection position 5 is bridged with the shear force sensor 3 of the N+3th detection position 5, where N = 1, 3, 5, 7, ...

[0040] That is, shear sensor bridges at the first and second detection positions, shear sensor bridges at the third and fourth detection positions, and so on; that is, shear sensor bridges at the first and fourth detection positions, shear sensor bridges at the third and sixth detection positions, and so on, thus obtaining continuous wheel load values ​​and continuous, blind-spot-free detection of wheel damage. The waveform of the vehicle load passing through the detection area is acquired, and by fitting several acquired waveforms, the influence of sleepers within the detection area is eliminated, thereby obtaining accurate wheel load detection values ​​(load force values).

[0041] S2: For one side of the rail, the processor acquires the waveforms of the shear force sensors at each detection position when the wheel passes through the detection zone. The horizontal axis of the waveform represents time, and the vertical axis represents the output value of the shear force sensor.

[0042] S3: Add the waveforms of the shear force sensors at the Nth detection position and the (N+3)th detection position to obtain the composite waveform.

[0043] For example, when N=1, the waveform of the shear force sensor at the first detection position is as follows: Figure 6 As shown, the waveform of the shear force sensor at the fourth detection position is as follows: Figure 7 As shown, the combined waveform of the two is as follows: Figure 8 As shown. For N = 3, 5, 7, ..., a similar series of synthesized waveforms can be obtained.

[0044] S4: Using the horizontal axis as the reference, display the various synthesized waveforms in chronological order on the same coordinate system to obtain the waveform curve.

[0045] For example, the waveform curve is as follows Figure 9 As shown.

[0046] S5: Based on the waveform curve, fit the top flat part of each synthesized waveform into a straight line, determine the load force according to the fitted straight line, and complete the weighing.

[0047] For example, after fitting, as shown Figure 10 As shown, this forms a continuous detection area from the first detection position to the last shear detection position. Figure 10 In the figure, the horizontal axis represents time, and the vertical axis represents shear force. The shear force value corresponding to the fitted straight line is the load force, thus achieving weighing.

[0048] Existing technologies require the removal of existing sleepers and their replacement with sleepers that can be fitted with weighing sensors. If it is an integral track bed or track slab, the sleeper section needs to be modified, with the original sleepers removed and replaced with sleepers suitable for installing vertical force sensors. This involves a large amount of construction work and a long period of time. In particular, the modification process requires coordination of issues such as the curing of new grouting materials and support during the transition period. Therefore, it usually requires a construction period of more than two months. At the same time, the changes to the original structure bring unknown safety hazards.

[0049] Compared with existing technologies, this invention does not use weighing sensors. Instead, it only requires the installation of shear force sensors on the rail between every two sleepers within the detection zone, preferably in the middle of the rail web. Two sets of shear force sensors are installed between adjacent sleepers. The shear force sensors are continuously arranged to obtain the required detection zone length. By continuously setting up the shear force sensors and implementing the specific bridge assembly and data processing scheme of this invention, the precise weight of the vehicle can be obtained.

[0050] This invention does not use weighing sensors, has a simple structure, is easy to install, and does not require modification of existing roadbeds, sleepers, or fasteners. It can complete projects that cannot be completed by existing technologies, such as high-speed rail and subways, which are sensitive to modification and have limited construction time (short maintenance windows, usually 3 hours per day), thus reducing construction time, cost, and safety hazards caused by construction.

[0051] The aforementioned inspection area is located on the straight section of the rail, and its length is greater than the circumference of the wheel, allowing for complete wheel inspection and eliminating blind spots. The distance between the inspection position closest to the sleeper and the sleeper is not less than half the height of the rail, and the distance between two adjacent inspection positions within two adjacent sleepers ranges from 200 to 300 mm, preferably 270 mm.

[0052] Two shear sensors are installed at each detection position, and the two shear sensors at the same detection position are symmetrically installed on both sides of the detection position on the rail web.

[0053] For example, within the testing area, two pairs of H-shaped shear force sensors are installed on each side of the rail between every two sleepers. One shear force sensor is installed at the same cross-sectional position on each side of a single rail, and these two shear force sensors constitute one pair. Shear force sensors are installed on the other side of the rail in the same manner.

[0054] The aforementioned shear force sensor is mounted on the web 4 of rail 1 via mounting bracket 6, wherein:

[0055] The mounting bracket 6 includes two symmetrical bracket units 7 and 8, which are symmetrically arranged on both sides of the rail 1. The upper part of each bracket unit 7 or 8 is pressed against the side of the rail web 4 of the rail 1 by the first set of bolts 11, and the lower parts of the two bracket units 7 and 8 are connected and fastened together by the second set of bolts 12.

[0056] Specifically, each support unit 7 or 8 includes a sensor mounting part 9 and a support unit connecting part 10. The sensor mounting part 9 is located at a set distance outside the rail web 4 of the rail 1, and the support unit connecting part 10 is located below the sensor mounting part 9 and extends from the bottom of the rail 1 to the inside of the rail 1.

[0057] The shear sensor 3 is pressed onto the side of the rail web 4 of the rail 1 by the first set of bolts 11 on the sensor mounting part 9 of each support unit 7 or 8, and the support unit connecting parts 10 of the two support units 7 and 8 are connected and fastened together by the second set of bolts 12.

[0058] The shape of the lower inner side of the support unit 7 or 8 corresponds to the shape of the lower part of the rail 1. During installation, the lower inner side of the support unit 7 or 8 is locked onto the lower part of the rail 1.

[0059] This invention eliminates the need for drilling or other damage to the existing rails. By using two symmetrical support units 7 and 8 to clamp the shear sensor 3 onto the side of the rail web 4, it reduces the safety hazards to the rails.

[0060] During installation, simply attach the sensor to the rail using bolts and tooling fixtures, and then connect the sensor cable to the trackside electrical control box. This completes the installation. Including debugging time, the process typically takes less than 15 hours. With a 3-hour maintenance window per day, a project can be completed in 5 days.

[0061] A disc spring washer 13 is provided between the first set of bolts 11 and the shear force sensor 3 for buffering, and a protective cover 14 is provided outside the mounting bracket 6 to protect the internal structure.

[0062] Once a wheel is damaged, the mechanical characteristics such as vibration under load will be reflected in the waveform curve. Based on the characteristics of the load, tread damage can be detected. Therefore, the detection method of this invention may further include:

[0063] S6: Based on the waveform curve, the top flat part of each synthetic waveform is fitted with a curve, and the damage type of the wheel tread is determined according to the shape characteristics of the fitted curve.

[0064] The fitted curve obtained by fitting is as follows: Figure 11 As shown, when the wheel tread is damaged, the instantaneous center of rotation of the wheel changes as it rotates. This change causes the wheel to generate a vertical impact velocity on the rail, thus producing an impact load (such as...). Figure 11 (As shown). By analyzing the characteristics of the impact load, the damage to the wheel tread and the type of damage can be determined.

[0065] Specifically, S6 includes:

[0066] The shape characteristics of the fitted curve are compared with the pre-obtained curve characteristics of various damage types, and the damage type of the wheel tread is determined based on the similarity.

[0067] The curve characteristics of various damage types are obtained in advance through the following process:

[0068] 1. Pre-obtain fitting curves for wheels without tread defects and wheels with various types of tread damage when passing through the detection zone.

[0069] First, shear force data of wheels without tread defects passing through the detection area were collected under different loads and speeds. The shear force data were then statistically analyzed to determine the wheel-rail force curve characteristics of the wheels without tread defects.

[0070] Then, multiple sets of shear force data for a certain type of tread damage, such as polygonal defects and wheel flat scar defects, were collected; statistical analysis was performed on the above shear force data to analyze the wheel-rail force curve characteristics of the wheel with this type of tread damage. Figure 12 and Figure 13 Examples of fitted curves for wheel flat scar defects and polygonal defects are given respectively.

[0071] 2. Determine the curve characteristics of various damage types in advance based on the difference between the fitted curve of the wheel passing through the inspection area with the fitted curve of the wheel without tread defects.

[0072] This involves analyzing the differences between the two curves and extracting these differences as the basis for defect determination, i.e., the curve characteristics of the damage type. This process is performed on all known wheel tread damage types to determine the criteria for each type of tread damage.

[0073] After obtaining the curve characteristics of each damage type in advance, during detection, the shape characteristics of the actual obtained fitted curve are compared and analyzed with the curve characteristics of the corresponding damage on the wheel tread. The similarity of their geometric shapes is analyzed to determine the accuracy of this type of damage. If the accuracy is greater than 90% (which can be set), it is defined as this type of damage.

[0074] As an improvement to this embodiment of the invention, the method further includes:

[0075] S7: Using the selected detection position as a reference, obtain the fitting curve of the shear force sensor at the selected detection position for each wheel pair of the train when passing through the selected detection position.

[0076] For example, a shear force sensor at the first detection position in the train's direction of travel can be selected as the data acquisition source for wheel positioning.

[0077] S8: Using the horizontal axis as a reference, display the fitted curves of each wheel pair in the same coordinate system in chronological order to obtain a continuous waveform dataset.

[0078] As the train passes the shear force sensor at the detection location, the shear force sensor continuously acquires the wheel-rail force waveforms of each wheel pair passing through the shear force sensor; these waveforms are arranged in time sequence in the acquired waveform dataset.

[0079] S9: When the tread of a wheel is damaged, locate the number of the fitted curve on the continuous waveform dataset to obtain the wheel pair number.

[0080] S10: The train number is obtained by taking a picture and recognizing it through the set train number acquisition system. The damaged wheelset is located by the train number and the wheelset serial number.

[0081] The train number acquisition system is usually installed behind the detection area. It takes pictures of the train and identifies the train number through an algorithm.

[0082] S11: Based on the correspondence between the shear force sensors on both sides of the rails at the same detection position, the left or right wheel of the damaged wheelset is located, thus achieving the positioning of the damaged wheel.

[0083] The same detection location corresponds to two rails, which in turn corresponds to two sets of shear force sensors. Based on the matching curve of the damaged tread and the correspondence between the shear force sensors of the two rails, the left or right wheel of the wheel pair can be determined, thereby locating the damaged wheel.

[0084] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for detecting track load, characterized in that, The rails on both sides of the inspection area are inspected using the same method, which includes: For the rails on one side of the detection area, two detection positions are set on the web of a section of rail within every two adjacent sleepers. Each detection position is equipped with a shear force sensor, and each shear force sensor is connected to the processor. According to the order of the detection positions, the shear force sensors of the Nth detection position are bridged with those of the (N+1)th detection position, and the shear force sensors of the Nth detection position are bridged with those of the (N+3)th detection position, where N = 1, 3, 5, 7, ... For one side of the rail, the processor acquires the waveforms of the shear force sensors at each detection position when the wheel passes through the detection zone. The horizontal axis of the waveform is time, and the vertical axis is the output value of the shear force sensor. The waveforms of the shear force sensors at the Nth and (N+3)th detection positions are added together to obtain the composite waveform. Using the horizontal axis as a reference, the various synthesized waveforms are displayed in chronological order on the same coordinate system to obtain a waveform curve. Based on the waveform curve, the top flat portion of each synthesized waveform is fitted into a straight line, and the load force is determined according to the fitted straight line to complete the weighing.

2. The track load detection method according to claim 1, characterized in that, The detection area is located on the straight section of the rail. The length of the detection area is greater than the circumference of the wheel. The distance between the detection position closest to the sleeper and the sleeper is not less than half the height of the rail. The distance between two adjacent detection positions within two adjacent sleepers is 200-300 mm.

3. The track load detection method according to claim 2, characterized in that, Two shear sensors are installed at each detection position, and the two shear sensors at the same detection position are symmetrically installed on both sides of the detection position of the rail web.

4. The track load detection method according to claim 3, characterized in that, The shear force sensor is mounted on the web of the rail via a mounting bracket, wherein: The mounting bracket includes two symmetrical bracket units, which are symmetrically arranged on both sides of the rail. The upper part of each bracket unit is pressed against the rail web side by a first set of bolts, and the lower parts of the two bracket units are connected and fastened together by a second set of bolts.

5. The track load detection method according to claim 4, characterized in that, The support unit includes a sensor mounting part and a support unit connecting part. The sensor mounting part is located at a set distance outside the rail web of the rail, and the support unit connecting part is located below the sensor mounting part, and the support unit connecting part extends from the bottom of the rail to the inside of the rail. The shear force sensor is pressed against the rail web side of the rail by the first set of bolts on the sensor mounting part of each support unit, and the support unit connecting parts of two support units are connected and fastened together by the second set of bolts.

6. The track load detection method according to claim 5, characterized in that, A disc spring washer is provided between the first set of bolts and the shear force sensor, and a protective cover is provided outside the mounting bracket.

7. The track load detection method according to claim 5, characterized in that, The shape of the lower inner side of the support unit corresponds to the shape of the lower part of the rail.

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