An online testing method for railway vehicle wheel-rail longitudinal force and adhesion coefficient

Abstract

This invention discloses an online method for testing the longitudinal force and adhesion coefficient of the wheel / rail of railway vehicles. This method analyzes the forces acting on the wheelset to establish force and moment balance equations. Based on the longitudinal, transverse, and vertical accelerations of the axlebox vibration and the primary longitudinal, transverse, and vertical displacements on both sides of the axle, measured by acceleration sensors mounted on the axles, the wheel / rail vertical force and longitudinal force are calculated, and the adhesion coefficient is calculated. This method addresses issues such as existing testing methods ignoring the adhesion saturation effect, failing to consider the time-varying characteristics of the wheel / rail vertical force, and inadequately measuring the longitudinal force and adhesion coefficient.

Description

Technical Field

[0001] The present invention relates to the field of rail contact force measurement, and in particular to an online testing method for railway vehicle wheel-rail longitudinal force and adhesion coefficient. Background Art

[0002] When a railway vehicle's wheels come into contact with the rails, a contact patch is formed. This contact patch consists of an adhesion zone and a sliding zone. In the adhesion zone, the wheel and rail materials are in a pure rolling state, with no relative sliding. In the sliding zone, the wheel and rail slide, without rolling. The wheel-rail adhesion state directly determines the saturation limit of the longitudinal wheel-rail force, and thus the traction and braking performance of the train. When the longitudinal wheel-rail force is lower than the traction force, the wheels will spin, causing abnormal wheel-rail wear. When the longitudinal wheel-rail force is lower than the braking force, the wheels will slip, increasing the braking distance and seriously affecting the safety of train operation.

[0003] The wheel-rail adhesion coefficient is mainly affected by the third medium. Under conditions of moisture, oil, frost, fallen leaves, etc., the wheel-rail adhesion coefficient decreases rapidly. The adhesion coefficient of the dry and clean wheel-rail interface is higher. The adhesion coefficient can also be increased by appropriately spreading sand.

[0004] The wheel-rail adhesion coefficient can be measured on a rolling test bench. The longitudinal creep rate is calculated from the speed difference between the roller and the wheel, and the wheel-rail tangential force is calculated from the torque signal. The adhesion coefficient is the ratio of the tangential force to the vertical force. Online testing of the wheel-rail adhesion coefficient is difficult. Existing techniques primarily estimate it using braking force or traction, but this is not applicable in cases of adhesion saturation. Furthermore, the lack of time-varying wheel-rail vertical force information makes it difficult to accurately determine the wheel-rail adhesion coefficient for different sections along the entire line. Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides an online testing method for the longitudinal force and adhesion coefficient of the wheel-rail of a railway vehicle.

[0006] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0007] An online testing method for the longitudinal force and adhesion coefficient of a railway vehicle wheel rail comprises the following steps:

[0008] S1. Establishing a wheelset balance equation group based on the stress state of the wheelset during train operation;

[0009] S2. Collect the longitudinal, lateral, and vertical accelerations of the axlebox vibration along the train route, and simultaneously collect the longitudinal, lateral, and vertical displacements on both sides of the axle;

[0010] S3, calculating the wheel-rail vertical force and the wheel-rail longitudinal force on the left and right sides of the wheelset based on the equilibrium equations established in S1 and the data collected in S2;

[0011] S4. Based on the wheel-rail vertical force and wheel-rail longitudinal force obtained in S3, calculate the wheel-rail adhesion coefficients on the left and right sides according to the adhesion coefficient formula.

[0012] Furthermore, the balance equations in S1 include: longitudinal balance equation, rolling balance equation, and head shaking balance equation, which are expressed as:

[0013] F=ma

[0014]

[0015] m w a z ·l c / 2+Q s1 l1-Q s2 ·l2+G·l c / 2-Q1·l c +H·r0=0

[0016] m w a z ·l c / 2+Q s2 l1-Q s1 ·l2+G·l c / 2-Q2·l c -H·r0=0

[0017] Where m is the unsprung mass, m w is the axle mass, G is the axle weight, F is the longitudinal external force, is the axle moment of inertia, L C is the distance between the wheels on both sides, L s is the distance between the axle boxes on both sides, l1 is the distance between the wheel and the axle box on the other side, l2 is the distance between the wheel and the axle box on the same side, a is the longitudinal acceleration, is the angular acceleration, F XR is the right longitudinal force, F XL is the left longitudinal force, F y is the lateral force, Q s1 is the vertical force of the left axle box, Q s2 is the vertical force of the right axle box, a z is the vertical acceleration, H is the wheel-rail lateral force, Q xl is the left wheel-rail vertical force, Q xr is the right wheel-rail vertical force.

[0018] Furthermore, in S2, the longitudinal / lateral / vertical acceleration of the axle box vibration is collected by an acceleration sensor installed on the axle, the longitudinal / lateral / vertical displacements of the two sides of the axle are collected by a displacement sensor, and the three-dimensional acceleration of the wheelset is calculated by derivatizing the three-dimensional displacement of the wheelset.

[0019] Furthermore, the wheel-rail vertical force and wheel-rail longitudinal force on the left and right sides in S3 are calculated as follows:

[0020] Q xl =(k s d zl +c d d′ zl )·(l s / 2+l c / 2) / l c -(k s d zr +c d d′ zr )·(l s / 2-l c / 2) / l c +G / 2+m w a z / 2+H·r0 / l c Q xr =(k s d zr +c d d′ zr )·(l s / 2+l c / 2) / l c -(k s d zl +c d d′ zl )·(l s / 2-l c / 2) / l c +G / 2+m w a z / 2+H·r0 / l c

[0021]

[0022] Where Q xl is the left wheel-rail vertical force, Q xr is the right wheel-rail vertical force, F xl is the left wheel-rail longitudinal force, F xr is the right wheel-rail vertical force, d xl d xr is the longitudinal displacement and vertical displacement of the left wheelset, d zl d zr is the longitudinal displacement and vertical displacement of the right wheelset, d y is the lateral displacement of the wheelset, d′ xl , d′ xr is the longitudinal speed and vertical speed of the left wheel pair, d′ zl , d′ zris the longitudinal speed and vertical speed of the right wheelset, d′ y is the lateral speed of the wheelset, a l 、a r is the longitudinal acceleration of the left and right axle boxes, k x 、k y 、k z is the longitudinal / lateral / vertical stiffness of the system, c x 、c y 、c z is a series of longitudinal / lateral / vertical damping, L c Indicates the distance between the left and right wheels, L s Indicates the distance between the left and right axle boxes, m is the unsprung mass, m w is the axle mass, G is the axle weight, and H is the wheel-rail lateral force.

[0023] Furthermore, the adhesion coefficient in S4 is calculated as follows:

[0024]

[0025] Where μ l 、μ r are the left and right wheel-rail adhesion coefficients, F xl is the wheel-rail longitudinal force on the left side of the wheelset, Q xl is the vertical wheel-rail force on the left side of the wheelset, F xr is the longitudinal wheel-rail force on the right side of the wheelset, Q xr Vertical wheel-rail force on the right side of the wheelset.

[0026] The present invention has the following beneficial effects:

[0027] The present invention solves the problems of existing testing methods such as neglecting the adhesion saturation effect, not considering the time-varying characteristics of the wheel-rail vertical force, and insufficient accuracy in testing the longitudinal force and adhesion coefficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The figure is a flow chart of the online testing method for the longitudinal force and adhesion coefficient of the wheel-rail of railway vehicles according to the present invention.

[0029] Figure 2a This is a schematic diagram showing the comparison between the calculated left longitudinal force and the actual left longitudinal force in the straight-line working condition simulation verification of an embodiment of the present invention.

[0030] Figure 2b This is a schematic diagram showing the comparison results between the right longitudinal force calculated in the straight-line working condition simulation verification of an embodiment of the present invention and the actual right longitudinal force.

[0031] Figure 2c Schematic diagram showing the comparison between the calculated left adhesion coefficient and the actual left adhesion coefficient in the simulation verification of the straight-line working condition according to an embodiment of the present invention.

[0032] Figure 2d Schematic diagram showing the comparison between the calculated right-side adhesion coefficient and the actual right-side adhesion coefficient in the simulation verification of the straight-line working condition according to an embodiment of the present invention.

[0033] Figure 3a This is a schematic diagram showing the comparison results between the calculated left longitudinal force and the actual left longitudinal force in the simulation verification of the R2800m working condition of an embodiment of the present invention.

[0034] Figure 3b This is a schematic diagram showing the comparison results between the right longitudinal force calculated in the simulation verification of the R2800m working condition of an embodiment of the present invention and the actual right longitudinal force.

[0035] Figure 3c Schematic diagram of the comparison between the left adhesion coefficient calculated in the simulation verification of the R2800m working condition of an embodiment of the present invention and the actual left adhesion coefficient.

[0036] Figure 3d Schematic diagram of the comparison results between the right-side adhesion coefficient calculated in the simulation verification of the R2800m working condition of an embodiment of the present invention and the actual right-side adhesion coefficient.

[0037] Figure 4a This is a side view of the sensor arrangement according to an embodiment of the present invention.

[0038] Figure 4b This is a front view of the sensor arrangement position according to an embodiment of the present invention. DETAILED DESCRIPTION

[0039] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the concepts of the present invention are protected.

[0040] An online testing method for the longitudinal force and adhesion coefficient of the wheel rail of a railway vehicle, such as Figure 1 As shown, the following steps are included:

[0041] S1. Establishing a wheelset balance equation group based on the stress state of the wheelset during train operation;

[0042] In this embodiment, based on the analysis of the stress state, the wheelset longitudinal balance equation, the lateral rolling balance equation, and the lateral shaking balance equation are established:

[0043] F= ma (1)

[0044]

[0045] m w a z ·l c / 2+Q s1 l1-Q s2 ·l2+G·l c / 2-Q1·l c +H·r0=0 (3)

[0046] m w a z ·l c / 2+Q s2 l1-Q s1 ·l2+G·l c / 2-Q2·l c -H·r0=0 (4)

[0047] The meanings of the parameters in the above formula are as follows:

[0048] F=F XR +F XL (5)

[0049] F XR =F xr +k x d xr +c x d′ xr (6)

[0050] F XL =F xl +k x d xl +c x d′ xl (7)

[0051] F y =k y d y +c y d′ y (10)

[0052]

[0053] Q sl =k z d zl +c z d′ zl (13)

[0054] Q sr =k z d zr +c z d′ zr (14)

[0055] Where d xl d xr d zl d zr is the longitudinal displacement and vertical displacement of the left and right wheelsets, d y is the lateral displacement of the wheelset, d′ xl , d′ xr , d′ zl , d′ zr is the longitudinal speed and vertical speed of the left and right wheels, d′ y is the lateral speed of the wheelset, a l 、a r is the longitudinal acceleration of the left and right axle boxes, k x 、k y 、k z is the longitudinal / lateral / vertical stiffness of the system, c x 、c y 、c z is a series of longitudinal / lateral / vertical damping, L c Indicates the distance between the left and right wheels, L s Indicates the distance between the left and right axle boxes

[0056] S2. Collect the longitudinal, lateral, and vertical accelerations of the axlebox vibration along the train route, and simultaneously collect the longitudinal, lateral, and vertical displacements on both sides of the axle;

[0057] In this embodiment, the required parameters are measured on the running line: the three-dimensional acceleration of the axle box and the three-dimensional displacement / velocity of the primary system. The acceleration sensor installed on the axle collects the longitudinal / lateral / vertical acceleration of the axle box vibration, and the displacement sensor collects the longitudinal / lateral / vertical displacement of the primary system on both sides of the axle. The three-dimensional velocity of the wheelset can be obtained by derivatizing the three-dimensional displacement. In this embodiment, longitudinal / lateral / vertical acceleration sensors are arranged on the axle boxes on the left and right sides of the bogie, and longitudinal / lateral / vertical displacement sensors are arranged on the left and right primary systems. The sensor layout diagram is shown as follows. Figure 4a and Figure 4b As shown, the longitudinal / vertical displacement sensors need to be arranged symmetrically on both sides, and the lateral displacement sensor can be arranged on one side to collect the longitudinal / lateral / vertical acceleration of the axle box and the longitudinal / lateral / vertical displacement of the first series.

[0058] The data acquisition device collects data through sensors and transmits it to the computing device. The computing device analyzes and calculates the data to obtain the data at different times of the train. When there are two axle boxes on one side, the longitudinal acceleration of the axle box vibration is divided by the average longitudinal acceleration of the front and rear axle boxes:

[0059] a l =a lf +a lb

[0060] ar =a rf +a rb

[0061] Where a lf 、a rf is the longitudinal acceleration of the left and right front axle boxes, a lb 、a rb is the longitudinal acceleration of the left and right rear axle box vibration

[0062] S3, calculating the wheel-rail vertical force and the wheel-rail longitudinal force on the left and right sides of the wheelset based on the equilibrium equations established in S1 and the data collected in S2;

[0063] Substituting (5)-(14) into (1)-(4) we can get the vertical wheel-rail force Q on the left side of the wheelset. xl and the right wheel-rail vertical force Q xr The expression of the left wheel-rail longitudinal force F of the wheelset is xl and the right wheel-rail longitudinal force F xr The expression:

[0064] Q xl =(k s d z1 +c d d′ z1 )·(l s / 2+l c / 2) / l c -(k s d z2 +c d d′ z2 )·(l s / 2-l c / 2) / l c +G / 2+m w a z / 2+H·r0 / l c

[0065] Q xr =(k s d z2 +c d d′ z2 )·(l s / 2+l c / 2) / l c -(k s d z1 +c d d′ z1 )·(l s / 2-l c / 2) / l c +G / 2+m w a z / 2+H·r0 / l c

[0066]

[0067] S4. Based on the wheel-rail vertical force and wheel-rail longitudinal force obtained in S3, calculate the wheel-rail adhesion coefficients on the left and right sides according to the adhesion coefficient formula.

[0068] Substituting the measured parameters into the formula, the vertical and longitudinal forces on the left and right sides of the wheelset can be calculated when the train is running. Then, according to the adhesion coefficient formula, the expression of the left and right wheel-rail adhesion coefficient can be obtained as follows:

[0069]

[0070] Simulation verification. Use dynamic simulation software to perform simulation analysis based on the line conditions. Simulate the straight line and the curved R2800m line respectively, and output the three-axis acceleration of the axle box and the three-axis displacement / velocity of the first system. Use the formulas in steps three and four to calculate and compare them with the longitudinal force and adhesion coefficient output by the software. Figure 2a 、 Figure 2b 、 Figure 2c 、 Figure 2d 、 Figure 3a 、 Figure 3b 、 Figure 3c 、 Figure 3d As shown in the figure, the difference between the calculated result and the actual result is very small.

[0071] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0072] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0073] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0074] Specific embodiments are used in the present invention to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas. At the same time, for those skilled in the art, according to the ideas of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

[0075] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and it should be understood that the scope of protection of the present invention is not limited to such specific descriptions and embodiments. Those skilled in the art can make various other specific variations and combinations based on the technical teachings disclosed in the present invention without departing from the essence of the present invention, and such variations and combinations are still within the scope of protection of the present invention.

Claims

1. A method for online testing of longitudinal wheel-rail force and adhesion coefficient of railway vehicles, characterized in that: The steps include: S1. Based on the stress state of the wheelset, a wheelset balance equation group including the longitudinal balance equation, the rolling balance equation, and the head-sway balance equation is established, wherein the longitudinal balance equation is expressed as: The roll balance equation is expressed as: The balance equation of the shaking head is expressed as: Where, is the unsprung mass, is the axle mass, is the axle weight, is the longitudinal resultant external force, is the axle moment of inertia, is the distance between the wheels on both sides, is the distance between the axle boxes on both sides, is the distance between the wheel and the axle box on the other side, is the distance between the wheel and the axle box on the same side, is the longitudinal acceleration, is the angular acceleration, is the right longitudinal force, is the left longitudinal force, is the lateral force, is the vertical force of the left axle box, is the vertical force of the right axle box, is the vertical acceleration, is the wheel-rail lateral force, is the left wheel-rail vertical force, is the right wheel-rail vertical force; S2. The longitudinal, lateral, and vertical accelerations of the axle box vibration are collected by an acceleration sensor installed on the axle, and the longitudinal, lateral, and vertical displacements on both sides of the axle are collected by a displacement sensor, wherein: S3. Calculate the wheel-rail vertical force and wheel-rail longitudinal force on the left and right sides of the wheelset in real time based on the equilibrium equations and the collected three-dimensional acceleration and displacement data. The calculation method for the wheel-rail vertical force and wheel-rail longitudinal force on the left and right sides is: Where, is the left wheel-rail vertical force, is the right wheel-rail vertical force, is the left wheel-rail longitudinal force, is the right wheel-rail longitudinal force, 、 The left wheelset longitudinal displacement and vertical displacement are respectively: 、 They are the longitudinal displacement and vertical displacement of the right wheelset, is the lateral displacement of the wheelset, 、 The left wheelset longitudinal speed and vertical speed are respectively: 、 They are the longitudinal speed and vertical speed of the right wheelset, is the wheelset lateral speed, 、 They are the longitudinal acceleration of the left and right axle boxes respectively, 、 、 They are longitudinal / lateral / vertical stiffness, 、 、 They are longitudinal / lateral / vertical damping, is the unsprung mass, is the axle mass, is the axle weight, is the wheel-rail lateral force; S4. Based on the wheel-rail vertical force and wheel-rail longitudinal force obtained in S3, calculate the wheel-rail adhesion coefficients on the left and right sides according to the adhesion coefficient formula. The adhesion coefficient is calculated as follows: Where, are the left and right wheel-rail adhesion coefficients, is the left wheel-rail longitudinal force of the wheelset, is the vertical wheel-rail force on the left side of the wheelset, is the right wheel-rail longitudinal force of the wheelset, Vertical wheel-rail force on the right side of the wheelset.

2. The method for online testing of wheel-rail longitudinal force and adhesion coefficient of railway vehicles according to claim 1, characterized in that: In S2, the longitudinal / lateral / vertical acceleration of the axle box vibration is collected by the acceleration sensor installed on the axle, the longitudinal / lateral / vertical displacement of the two sides of the axle is collected by the displacement sensor, and the three-dimensional acceleration of the wheelset is calculated by derivation of the three-dimensional displacement of the wheelset.

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