Testing method for the relationship between adhesion coefficient and slip rate based on large slip wheel-rail test bench

Abstract

Specifically, the present invention is a method for testing the relationship between adhesion coefficient and slip rate based on a large-slip wheel-rail test bench. Specifically, S1 applies or places a third medium on the track; S2 controls the first clutch and the second clutch to mesh the first gear set and the second gear set and the second gear set and the third gear set, starts the wheel speed motor to drive the pure roller and the sliding wheel to rotate, and pulls the frame to the target speed; S3 controls the extension and contraction of the cylinder to apply different axle loads; S4 controls the speed of the vehicle speed motor and the wheel speed motor to generate slip rates of different waveforms; S5 collects wheel-rail adhesion coefficient and slip rate data under different working conditions, plots the adhesion coefficient versus slip rate and the adhesion coefficient versus time curves, and finally obtains the wheel-rail adhesion characteristics and change laws under different working conditions. Advantages of the present invention: It realizes tests with greater slip and different waveform slip rates, studies adhesion characteristics under large-slip working conditions; and simulates the dynamic changes and quantitative research of the amount of the third medium under real rail surface conditions.

Description

Technical Field

[0001] The present invention relates to the field of railway vehicle wheel-rail adhesion characteristic testing, and in particular to a method for testing the relationship between adhesion coefficient and slip rate based on a large-slip wheel-rail test bench. Background Art

[0002] Currently, railway vehicles rely on wheel-rail adhesion for both traction and braking. Wheel-rail adhesion has become a pressing technical bottleneck and challenge hindering the further speed increases and operational safety of high-speed trains. Insufficient wheel-rail adhesion can easily lead to traction slippage, braking slippage, or even locking of the train, causing wheel tread abrasions and rail damage, increasing maintenance costs. The resulting vibration disturbances can also affect the smoothness and comfort of the train's operation. Furthermore, traction slippage can easily lead to stopping on slopes and slowing down, as well as motor damage. Braking slippage can extend braking distances, preventing rapid stopping and making it more prone to major safety accidents such as overshooting and even derailment. Wheel-rail adhesion significantly impacts the economic efficiency, stability, and safety of train operation. Therefore, conducting wheel-rail adhesion tests and studying the variation patterns of the wheel-rail adhesion coefficient are of great engineering significance and value.

[0003] Due to the complex and costly testing process for actual train lines, as well as the difficulty in ensuring the operational safety of the test trains, wheel-rail adhesion testing is currently primarily conducted using simple-to-operate, low-cost scaled-down test benches. Current domestic research on wheel-rail adhesion characteristics primarily utilizes rolling test benches, which are simple to operate, offer high control precision, and are capable of simulating wheel-rail adhesion under most operating conditions. However, these "double-wheel rolling" test benches cannot quantitatively control the thickness of the third medium on the rail surface, and both the wheels and rail wheels experience significant vibration under high-slip conditions, resulting in low test accuracy for these conditions. Therefore, the corresponding test methods on rolling test benches are inaccurate and difficult to test for wheel-rail adhesion characteristics under high-slip conditions, and are unable to measure the impact of dynamic changes in the amount of third medium on the rail surface during train operation. A multifunctional wheel-rail adhesion creep testing machine and simulation test method (application number CN202211301015.2) provides a multifunctional wheel-rail adhesion simulation testing machine and method, which realizes simulation tests of various working conditions such as wheel-rail adhesion, parking braking, long downhill uniform speed movement, and long uphill uniform speed traction. However, the implementation scheme described in this document can only test the wheel-rail adhesion characteristics under small creep conditions. It has certain limitations for testing the wheel-rail adhesion characteristics under slip rate conditions with varying variations over a wider range. It is also unable to simulate and test the impact of dynamic changes in the third medium volume on the rail surface caused by the rolling of the front wheels of the train on the adhesion coefficient of the rear wheels. The "Method and Test Bench for Measuring the Relationship between the Adhesion Coefficient and Slip Ratio of Railway Vehicles Under Braking" (Application No. CN201910823653.2) provides a method and test bench for measuring the relationship between the adhesion coefficient and slip ratio of railway vehicle braking, which fully reflects the braking adhesion characteristics at higher speeds. However, the implementation scheme described in this document can only simulate and test the wheel-rail adhesion characteristics during the actual braking anti-skid process of existing trains, and cannot test the adhesion coefficient under arbitrary slip ratio waveform conditions. Therefore, to a certain extent, it limits the further possibilities of optimizing the utilization of braking anti-skid adhesion, and it is relatively difficult to test the wheel-rail adhesion characteristics under large slip conditions.

[0004] In order to solve the above-mentioned defects of the existing technical problems or provide an alternative test method for the relationship between wheel-rail adhesion coefficient and slip rate, it is necessary to propose a new wheel-rail adhesion characteristic test method. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a large-slip wheel-rail test bench and a method for testing the relationship between adhesion coefficient and slip rate. The test bench is used to customize and simulate the wheel-rail adhesion characteristics and their variation patterns under different operating conditions, optimize the research on wheel-rail adhesion theory and adhesion control strategy, and improve train operation safety.

[0006] In order to achieve the above objectives, a method for testing the relationship between adhesion coefficient and slip rate based on a large-slip wheel-rail test bench is designed, and the method is specifically as follows: S1. Apply or place a third medium on the track; S2. Control the first clutch and the second clutch to engage the first gear set and the second gear set and the second gear set and the third gear set, start the wheel speed motor, drive the pure roller and the sliding wheel to rotate, and pull the frame to the target speed; S3. Control the telescopic end of the cylinder to press against the lower surface of the frame to apply different axle loads; S4. Control the second clutch to separate the second gear set and the third gear set, and control the speed of the vehicle speed motor and the wheel speed motor respectively to generate slip rates of different waveforms; S5. Collect wheel-rail adhesion coefficient and slip rate data under different working conditions, draw adhesion coefficient versus slip rate and adhesion coefficient versus time curves, and finally obtain the wheel-rail adhesion characteristics and change laws under different working conditions.

[0007] Preferably, step S4 of the present invention includes setting a target slip rate, which is divided into three types: fixed slip, sinusoidal wave and file wave. The fixed slip inputs a constant target slip rate value, which is used to study the wheel-rail adhesion characteristics under the adhesion improvement effect of the front wheel to the rear wheel of the train under a fixed slip rate working condition; the sinusoidal wave inputs the target slip rate upper limit value and the slip rate change period, and the vehicle speed motor and the wheel speed motor will control the slip rate to change periodically in the form of a sine wave, and the slip rate upper limit is set to a maximum of 100%, which is used to study the wheel-rail adhesion characteristics under large slip conditions; the file wave inputs a custom slip rate waveform data file, and inputs a triangular wave or other different waveforms, which is used to study the influence of different waveform slip rates on the wheel-rail adhesion characteristics. It can also input the slip rate change waveform during the actual train anti-skid control process, which is used to study the wheel-rail adhesion characteristics during the actual train braking anti-skid process.

[0008] Preferably, the test bench of the present invention includes a test bench base, the test bench base is provided with a surround-type track; a frame, the frame is provided with a pure roller and a sliding wheel, which can circle on the track; the pure roller is installed on the first wheel axle, the first wheel axle is provided with a first gear, the first gear is meshed with one end of the first gear set, the other end of the first gear set is matched with one end of the second gear set through a clutch, the second gear set is driven by the vehicle speed motor, the other end of the second gear set is matched with one end of the third gear set through the second clutch, one gear of the third gear set is sleeved on the wheel speed motor drive shaft, the other end of the third gear set is installed on the second wheel axle, the second wheel axle is provided with a sliding wheel, the first wheel axle and the second wheel axle are both provided with a cylinder, the telescopic end of the cylinder is used to abut against the lower surface of the frame.

[0009] Preferably, the pure roller of the present invention is used to simulate vehicle speed, the sliding wheel is used to simulate axle speed, and the cylinder is used to simulate axle weight.

[0010] Preferably, the first axle and the second axle of the present invention further include a data collection component for collecting data, and the data collection component includes a speed sensor and a torque meter.

[0011] Preferably, the test bench of the present invention is further provided with a third medium spraying device for spraying a third medium onto the rail surface.

[0012] Compared with the prior art, the present invention has the following advantages:

[0013] 1. The present invention controls slip by controlling the vehicle speed and axle speed respectively through the vehicle speed and wheel speed motors. Compared with the existing technology, it can achieve tests with larger slip and can conduct tests with different waveform slip rates. The control is more flexible, providing more possibilities for optimizing the use of brake anti-skid adhesion, and can also study the adhesion characteristics under large slip conditions.

[0014] 2. The test bench of the present invention adopts a wheel-circling type, which can simulate the dynamic changes in the amount of third media such as water, oil, and leaves under real track surface conditions. The existing technology cannot quantitatively control the third medium on the track surface. Therefore, the test method of this patent can also conduct quantitative research on the third medium on the track surface, which can more accurately study the wheel-rail adhesion characteristics when the third medium on the track surface exists.

[0015] 3. During the braking or acceleration of a rail vehicle, slippage may occur between the drive wheel and the track. In existing slippage testing methods, the slippage period is short, and the slippage test period is also short. This application uses PID control of a pure roller to maintain the vehicle speed required for the experiment, while controlling the slippage between the sliding wheel and the track. This lengthens the slippage period between the track and the drive wheel, and the corresponding slippage test period. This also provides more data samples for parameters such as the slip rate and track adhesion coefficient that can be measured, which helps to improve and optimize the research on track slippage. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the test bench structure of the present invention;

[0017] Figure 2 This is a schematic diagram of the connection relationship between the components of the test bench of the present invention;

[0018] Figure 3 It is a schematic flow chart of the main steps of the method of the present invention;

[0019] Figure 4 It is a flow chart of the independent variable control method in the test method of the present invention;

[0020] In the figure: 1 test bench base; 2 track; 3 frame; 4 pure roller; 4-1 first wheel axle; 4-2 first gear; 5 sliding wheel; 5-1 second wheel axle; 6 first gear set; 6-1 second gear set; 6-2 third gear set; 7 cylinder; 8 wheel speed motor; 9 vehicle speed motor; 10 data acquisition component. DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to specific embodiments.

[0022] The present invention provides a method for testing the relationship between adhesion coefficient and slip rate based on a large-slip wheel-rail test bench. After the test bench wheels are towed to the target speed, the pressure of the cylinder above the wheel axle is controlled by charging and exhausting, thereby applying different axle loads. The speeds of the vehicle speed motor and the wheel speed motor are controlled to generate slip rates of different waveforms. Wheel-rail adhesion coefficient and slip rate data under different operating conditions are collected, and adhesion coefficient versus slip rate and adhesion coefficient versus time curves are plotted. Ultimately, the wheel-rail adhesion characteristics and their variation patterns under different operating conditions are obtained. The present invention provides a test method and step-by-step process for studying wheel-rail adhesion characteristics under different operating conditions, which is of great significance for the research on wheel-rail adhesion theory and the optimization of adhesion control strategies, and for ensuring train operation safety.

[0023] To address the technical issues such as low accuracy and difficulty in testing wheel-rail adhesion characteristics under large slip conditions, inability to simulate and test the impact of dynamic changes in the third medium volume on the rail surface caused by the rolling of the front wheel of the train on the improvement of the adhesion coefficient of the rear wheel, and inability to test adhesion characteristics under conditions of arbitrary slip rate changing with time, this patent combines the advantages of a winding wheel-rail adhesion test bench that can simulate large slip conditions, comprehensively considers functions such as constant slip, sine wave, and file wave, and can simulate more complex conditions such as front wheel to rear wheel adhesion improvement, large slip, and arbitrary slip rate waveforms. It is relatively simple to operate and has high control accuracy. The test data can provide data support and factual basis for the changing laws of wheel-rail adhesion characteristics under different train operating conditions. It is of great value to the theoretical research and engineering application of multi-condition wheel-rail adhesion characteristics, adhesion control, and optimal utilization, and has practical significance for ensuring the traction and braking performance and operation safety of trains.

[0024] This patent is based on a circling, high-slip wheel-rail adhesion simulation test bench. A third medium is applied or placed on the rail surface, and the test bench is towed to the target speed. The pressure of the cylinder above the wheel axle is controlled by filling and exhausting the cylinder, thereby applying different axle loads. The speed of the vehicle speed motor and wheel speed motor are controlled to generate different slip waveforms. Wheel-rail adhesion coefficient and slip rate data are collected under different operating conditions. Adhesion coefficient versus slip rate and adhesion coefficient versus time curves are plotted, ultimately revealing the wheel-rail adhesion characteristics and variations under different operating conditions. Based on this approach, the speed, axle load, and slip rate control principles are incorporated into the control panel, enabling automatic testing of the adhesion coefficient and slip rate relationship based on different vehicle operating conditions and plotting the curves.

[0025] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the method of the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] Example 1:

[0027] The test bench is a large slip wheel-rail adhesion simulation test bench. Figure 1 、 Figure 2 As shown, it includes a frame 3, a vehicle speed motor 9, a wheel speed motor 8, a track 2, a pure roller 4 for simulating vehicle speed, a sliding wheel 5 for simulating axle speed, a cylinder 7 for simulating axle weight, and a data collection component 10 including a speed sensor and a torque meter for collecting data. It also includes a host computer for collecting data, a control cabinet, a load valve for filling and exhausting the cylinder and a load air duct connected to it, a third medium spraying device for spraying a third medium onto the track surface, and other equipment.

[0028] Preparation of the test equipment includes: turning on the main power switch and all control device panels; pressing the vehicle speed motor and wheel speed motor clutches to engage the control gears connecting the two wheel axles inside the test bench; establishing test condition data collection and recording files; turning on the third medium spraying device to spray liquid third medium on the rail surface for several seconds or placing solid third medium such as leaves and crushing it into a film with the wheels to simulate different rail surface third medium conditions.

[0029] The test process is as follows Figure 3 As shown, specifically including:

[0030] Before operating the test bench, the track surface media conditions must be set. The speed motor is then controlled to pull the test bench to the target speed for the test condition. The cylinders above the wheel axles are inflated, applying axle loads to the wheels and adjusting them to the target axle load. The target slip ratio is set on the control panel. Fixed slip requires a constant target slip ratio value, primarily used to study the wheel-rail adhesion characteristics under fixed slip conditions, where the front wheel improves the adhesion of the train to the rear wheel.

[0031] The dynamically changing vehicle speed, axle speed, and torque data are collected during the test, and the slip rate and adhesion coefficient are calculated in real time. The slip rate calculation formula at different times is:

[0032] ;

[0033] Where S is the slip ratio, V C [km / h] is the pure roller speed (i.e. simulated vehicle speed), where V W [km / h] is the sliding wheel speed (i.e. the simulated shaft speed).

[0034] The formula for calculating the adhesion coefficient at different times is:

[0035] ;

[0036] Where μ is the adhesion coefficient at different times, T [N·m] is the torque measured at different times, R [m] is the wheel radius, N [t] is the simulated train axle weight, and g is the acceleration due to gravity (g ≈ 9.81 m / s 2 ).

[0037] By collecting real-time vehicle speed, axle speed, and torque data during test bench operation and calculating the slip ratio and adhesion coefficient, and plotting the relationship between the adhesion coefficient and slip ratio, the wheel-rail adhesion characteristics under the set operating conditions can be determined. The test was repeated three times for the same operating condition to eliminate random errors.

[0038] Select an axle load range of 11t-17t, conduct tests every 1t, and repeat the above test and data collection steps until all selected axle load tests are completed.

[0039] Select a speed range of 10km / h-100km / h, conduct tests every 10km / h, and repeat the above test and data collection steps until all selected speed tests are completed.

[0040] Select a speed range of 10km / h-100km / h, conduct tests every 10km / h, and repeat the above test and data collection steps until all selected speed tests are completed.

[0041] After the test, the test data under all working conditions were filtered to obtain the relationship and change law between the adhesion coefficient and slip rate under different working conditions.

[0042] The flow chart of the control method of vehicle parameter independent variables during the test process of the present invention is as follows: Figure 4The test process primarily uses the host computer's control panel to control the various variables. After entering the target vehicle speed and slip ratio into the control panel, the system automatically calculates the target axle speed based on the slip ratio formula. The control cabinet transmits electrical signals to the vehicle speed motor and wheel speed motor, respectively. The control cabinet's internal logic primarily utilizes PID control, which provides fast response and minimal overshoot. The vehicle speed motor rotates the swing arm and controls its speed (simulated vehicle speed) to the target vehicle speed. The wheel speed motor slides the sliding axle and controls its speed (simulated axle speed) to the target axle speed calculated based on the target vehicle speed and slip ratio. This effectively controls the resulting slip ratio to near the target. After entering the target axle weight into the control panel, the control cabinet automatically controls the rotation of the load valve, which flows air into or out of the cylinder above the wheel axle through the load air duct, keeping the cylinder pressure close to the target axle weight, thereby controlling the actual axle weight to the set target value. By controlling the vehicle speed, slip rate and axle load to different target values, the vehicle parameter values ​​that affect the wheel-rail adhesion coefficient can be arbitrarily set and changed, thereby forming different working conditions and conducting quantitative research on its wheel-rail adhesion characteristics.

[0043] Example 2:

[0044] On the basis of Example 1, when setting the target slip rate in the control panel, the fixed slip input in Example 1 can also be replaced with a sine wave. The sine wave requires the input of the target slip rate upper limit and the slip rate change period. The vehicle speed motor and the wheel speed motor will control the slip rate to change periodically in the form of a sine wave. The maximum slip rate upper limit can be set to 100%, which is mainly used to study the wheel-rail adhesion characteristics under large slip conditions.

[0045] Example 3:

[0046] Based on Example 1, when setting the target slip rate on the control panel, the fixed slip input in Example 1 can also be replaced with a file waveform. The file waveform requires a custom slip rate waveform data file. Different waveforms, such as triangular waves, can be input to study the impact of different slip rate waveforms on wheel-rail adhesion. Alternatively, the actual slip rate waveform during train anti-slip control can be input to study the wheel-rail adhesion characteristics during actual train braking and anti-slip control. Clicking the Generate Slip button on the control panel generates slip according to the set slip rate waveform.

[0047] It is worth noting that in the field of slip testing, a slip rate exceeding 30% is usually referred to as large slip; when the slip rate reaches 100%, the sliding wheel may be completely locked, and the shaft speed is 0 at this time. The wheel speed motor of the present invention can control the sliding wheel speed (i.e., the simulated shaft speed) to 0 to produce a large slip, which only requires the wheelset to stop rotating, without applying a large force, and therefore will not cause significant damage to the wheel rail. The existing technology requires a large torque to be controlled to lock the tire, and requires applying a huge force, which will cause significant damage to the tire, and therefore cannot achieve large slip.

[0048] In addition, the present invention simulates the actual train operating conditions by inputting the slip rate curve during anti-skid control during the operation of an actual track train. The slip rate curves in the prior art only have triangular waves and sine waves. Such curves can only be used for scientific research and have no practical design basis, so they have no engineering significance. The file wave can simulate the actual process and has higher engineering significance. It is of great significance for studying vehicle slip and improving vehicle driving safety.

[0049] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent replacement or change made by any technician familiar with the technical field within the technical scope disclosed by the present invention based on the technical solution and novel concept of the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for testing the relationship between adhesion coefficient and slip rate based on a large slip wheel-rail test bench, characterized in that The method is specifically as follows: S1. Apply or place a third medium on the track; S2. Control the first clutch and the second clutch to engage the first gear set and the second gear set and the second gear set and the third gear set, start the wheel speed motor, drive the pure roller and the sliding wheel to rotate, so that the frame is pulled to the target speed; S3. Control the telescopic end of the cylinder against the lower surface of the frame to apply different axle loads; S4. Control the second clutch to disengage the second gear set and the third gear set, respectively controlling the speed of the vehicle speed motor and the wheel speed motor to produce different waveforms of slip rate; S5. Collect wheel-rail adhesion coefficient and slip rate data under different operating conditions, plot adhesion coefficient versus slip rate and adhesion coefficient versus time curves, and ultimately determine the wheel-rail adhesion characteristics and variation patterns under different operating conditions; The test bench includes A test bench base, wherein the test bench base is provided with a surrounding track; The frame is provided with a pure roller and a sliding wheel, which can circle on the track; the pure roller is installed on the first wheel axle, and the first wheel axle is sleeved with a first gear, the first gear is meshed with one end of the first gear set, the other end of the first gear set is matched with one end of the second gear set through a clutch, the second gear set is driven by the vehicle speed motor, and the other end of the second gear set is matched with one end of the third gear set through the second clutch, one gear of the third gear set is sleeved on the wheel speed motor drive shaft, the other end of the third gear set is installed on the second wheel axle, and the second wheel axle is provided with a sliding wheel, and the first wheel axle and the second wheel axle are both provided with a cylinder, and the telescopic end of the cylinder is used to abut against the lower surface of the frame.

2. A method for testing the relationship between adhesion coefficient and slip rate based on a large slip wheel-rail test bench according to claim 1, characterized in that Step S4 includes setting a target slip rate. The target slip rate is divided into three types: fixed slip, sine wave, and file wave. The fixed slip inputs a constant target slip rate value, which is used to study the wheel-rail adhesion characteristics under the fixed slip rate working condition under the adhesion improvement effect of the front wheel to the rear wheel of the train; the sine wave inputs the target slip rate upper limit and the slip rate change period. The vehicle speed motor and the wheel speed motor will control the slip rate to change periodically in the form of a sine wave. The maximum slip rate upper limit is set to 100%, which is used to study the wheel-rail adhesion characteristics under large slip conditions; the file wave inputs a custom slip rate waveform data file. The input of a triangular wave or other different waveforms is used to study the impact of different waveform slip rates on the wheel-rail adhesion characteristics. It can also input the slip rate change waveform during the actual train anti-skid control process to study the wheel-rail adhesion characteristics during the actual train braking anti-skid process.

3. The method for testing the relationship between adhesion coefficient and slip rate based on a large slip wheel-rail test bench according to claim 1, characterized in that The pure roller is used to simulate vehicle speed, the sliding wheel is used to simulate axle speed, and the cylinder is used to simulate axle weight.

4. A method for testing the relationship between adhesion coefficient and slip rate based on a large slip wheel-rail test bench according to claim 1, characterized in that The first axle and the second axle also include a data collection component for collecting data, and the data collection component includes a speed sensor and a torque meter.

5. The method for testing the relationship between adhesion coefficient and slip rate based on a large slip wheel-rail test bench according to claim 1, characterized in that The test bench is also provided with a third medium spraying device for spraying the third medium onto the rail surface.

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