Device for testing linear driving swing amplitude of rear axle center of trailer relative to front axle center of tractor

Abstract

The utility model discloses a device for testing the linear driving swing amplitude of the rear axle center of a trailer relative to the front axle center of a tractor. Comprising a tractor gyroscope arranged at the center of a front axle of a tractor, a trailer gyroscope arranged at the center of a rear axle of the trailer and a datum line which is arranged on a test road and serves as a driving datum of the tractor in the test process. And a differential base station capable of acquiring coordinate positions of the tractor gyroscope and the trailer gyroscope is built on one side outside the test road. The problem that the measurement result is influenced by the environment temperature can be effectively solved, and the problem that the back-and-forth test cannot be carried out on the same road section of the same road in a short time can also be solved.

Description

Technical Field

[0001] The utility model belongs to the technical field of automobile train testing, and in particular relates to a device for testing the swing amplitude of a trailer rear axle center relative to a tractor front axle center during straight-line driving. Background Art

[0002] GB 7258-2017 "Technical Conditions for Motor Vehicle Operation Safety", GB / T 26778-2023 "Performance Requirements and Test Methods for Automobile Trains", and JT / T 1178.2-2019 "Technical Conditions for Safety of Operating Trucks Part 2: Towing Vehicles and Trailers" all have requirements for the maximum swing amplitude of the rear axle center of the trailer relative to the front axle center of the tractor. There are currently two commonly used test methods. One is to measure by the water spray method recorded in Appendix C of GB / T 25979-2010 "Test Methods for Lateral Stability of Road Vehicles Heavy Commercial Vehicles and Articulated Buses", and the other is to test the maximum swing amplitude of the trailer relative to the tractor in a straight line by the tire water spray method. In the two measurement processes, the test results of the maximum swing amplitude have a large dispersion, and multiple measurements are required to express the results through the average value and uncertainty. Since the test site cannot be guaranteed to be in a completely horizontal state, a round-trip test is required during the test, and the measurement result is a watermark, which can only be tested on a dry road surface.

[0003] When using the water spray method or tire water spray method for testing, the measured watermark is not a straight line, and it will become wider as the speed increases and the time increases. At the same time, the watermark will evaporate quickly due to the increase in ambient temperature, making it inconvenient to measure. That is, the ambient temperature for measurement must be at an appropriate temperature, and the same vehicle speed and time must be maintained for each test; at the same time, the test requires multiple measurements to find the average value. For example, when doing round-trip tests on the same section of the same road, in order to prevent the two watermarks from affecting each other, a wider road is required for measurement, and after multiple measurements, it is necessary to wait for the watermark to completely dry before testing again. In order not to affect the test efficiency and measurement results, the road width requirements are relatively large. In the process of the water spray method, in order to prevent crossing or occupying a faster road, the position of the water spray device on the tractor and trailer needs to be adjusted in one direction, and when testing by the tire water spray method, it will affect the performance of the tire. Utility Model Content

[0004] The utility model proposes a device for testing the swing amplitude of the rear axle center of a trailer relative to the front axle center of a tractor during straight-line driving, which can not only effectively solve the problem that the measurement result is affected by the ambient temperature, but also solve the problem that a round-trip test cannot be performed on the same section of the same road in a short time.

[0005] To this end, the technical solution adopted by the utility model is: a device for testing the swing amplitude of the rear axle center of a trailer relative to the front axle center of a tractor during straight-line driving, comprising a tractor gyroscope arranged on the front axle center of the tractor, a trailer gyroscope arranged on the rear axle center of the trailer, and a reference line arranged on a test road and used as a reference for the tractor during the test, and a differential base station capable of obtaining the coordinate positions of the tractor gyroscope and the trailer gyroscope is built on one side outside the test road.

[0006] As a preferred embodiment of the above scheme, the sampling frequency of the equipment in the differential base station is not less than 100 Hz, the data delay time is not greater than 0.01 s, and the measurement accuracy is not greater than 20 mm.

[0007] Further preferably, the differential base station includes a host computer and a receiver.

[0008] Beneficial effects of the utility model:

[0009] 1) The test effect is good. The test results are displayed through the differential base station, which can effectively solve the problem that the test results are affected by the ambient temperature. It also solves the problem that it is impossible to conduct round-trip tests on the same section of the same road in a short time. For the test results, there is no need to measure them, so it can effectively reduce the interference of artificial factors on the test results; at the same time, the test data can be saved during the entire test process, and its traceability is good.

[0010] 2) During the whole process, the vehicle only needs to travel back and forth, and there is no need to adjust other parts, thus ensuring the continuity of the test and reducing the impact of other conditions on the test results. The test can be carried out on wet and slippery roads.

[0011] 3) The measured swing amplitude is for the relative swing that occurs at the same time during the driving process of the vehicle. In the prior art, the measurement is carried out after the test is completed, and the swing amplitude of the tractor and the trailer at the same position is obtained. Compared with the two, the swing amplitude that occurs at the same time is more reasonable. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is the installation diagram of the utility model.

[0013] Figure 2 The figure is a vehicle driving trajectory diagram when the utility model is used in a specific test.

[0014] Figure 3 It is the swing amplitude of the first test in a specific test using the utility model.

[0015] Figure numerals: baseline-1, tractor-2, trailer-3, differential base station-4, test road-5, tractor front axle-6, tractor gyroscope-7, trailer rear axle-8, trailer gyroscope-9. DETAILED DESCRIPTION

[0016] The present invention will be further described below by way of embodiments and in conjunction with the accompanying drawings:

[0017] like Figure 1 As shown, a device for testing the swing amplitude of the rear axle center of a trailer relative to the front axle center of a tractor during straight-line driving is mainly composed of a tractor gyroscope 7, a trailer gyroscope 9, a reference line 1 and a differential base station 4. The differential base station is built on one side outside the test road, and mainly includes a host computer and a receiver, and the host computer adopts existing technologies with information processing and information interaction functions, such as a computer, and the receiver adopts existing technologies with information receiving and transmission functions, such as a differential GPS.

[0018] The tractor gyroscope 7 is set on the center of the tractor front axle 6 to measure the position of the center of the tractor front axle 6, and the differential base station 4 can obtain the coordinate positions of the tractor gyroscope 7 and the trailer gyroscope 9. The trailer gyroscope 9 is set on the center of the trailer rear axle 8 to measure the position of the center of the trailer rear axle 8 and transmit the obtained signal to the differential base station 4. The reference line 1 is set on the test road 5 and serves as the driving reference of the tractor 2 during the test. At the same time, the position of the reference line is also pre-stored in the differential base station as a reference for the relative offset of the center of the tractor front axle 6 and the center of the trailer rear axle 8 during the test.

[0019] To improve the accuracy of the test results, the sampling frequency of the equipment in the differential base station 4 is not less than 100 Hz, the data delay time is not greater than 0.01 s, and the measurement accuracy is not greater than 20 mm.

[0020] Based on the above device, a method for testing the swing amplitude of the rear axle center of a trailer relative to the front axle center of a tractor during straight-line driving is also provided, which specifically includes the following testing steps:

[0021] Step 1: Preparation before testing. Build the differential base station 4, and install the tractor gyroscope and the trailer gyroscope at the corresponding positions, and determine a certain length of test road and a baseline on the test road, and store the position of the baseline in the differential base station.

[0022] Step 2: Conduct the test. The vehicle equipped with the gyroscope is driven straight and at a constant speed from outside the test road to the test road. The vehicle is kept driving straight and at a constant speed with reference to the baseline on the test road. At the same time, the corresponding gyroscope is used to measure in real time the offset distance of the center of the tractor's front axle and the center of the trailer's rear axle relative to the baseline on the test road, and the distance is stored.

[0023] Step 3: Test result processing: According to the distance between the center of the tractor's front axle and the center of the trailer's rear axle relative to the baseline, the swing amplitude is obtained by the formula, and the largest swing amplitude is selected from the obtained swing amplitudes. The formula is as follows:

[0024] A i =Y 2i -Y 1i

[0025] Among them, i is the time the vehicle travels on the test road, A i is the swing amplitude of the vehicle at time i, Y 2i Y is the distance that the center of the trailer rear axle is offset from the reference line at time i, 1i It is the distance that the center of the tractor's front axle is offset from the reference line.

[0026] Step 4: Repeat the test to obtain the test results. Repeat steps S2 and S3 back and forth on the test road for at least three times to obtain at least 6 data, and calculate the average value and uncertainty of these 6 data.

[0027] Before the vehicle enters the test road for the first time, it is necessary to draw the warm-up lane line. The warm-up process is as follows: the vehicle is driven for no less than 30 minutes and no less than 30 kilometers to warm up the tires and ensure that all parts are lubricated normally. The warm-up action includes an acceleration of no less than 4m / s 2 Rapid acceleration or deceleration, figure 8 or snake-like movements, etc.

[0028] To ensure uniform and straight driving on the test road, the vehicle needs to drive in a straight line for no less than 80 meters each time before entering the test road.

[0029] To ensure the test results, the length of the test road shall not be less than 500m. At the same time, the speed of the vehicle on the test road shall be between 20km / h and 100km / h, which shall be determined according to needs. The vehicle shall remain unloaded during the test.

[0030] Now we take the articulated train with the parameters in Table 1 as the research object for specific experiments.

[0031] Table 1 Parameters of the research subjects

[0032] project Data or content Maximum swing amplitude limit / mm 110 Quality status of semi-trailer tractor Curb Weight Semi-trailer tractor length × width × height / mm 6878×2549×3507 Semi-trailer quality status No load Semi-trailer length × width × height / mm 12450×2550×1660 Container height / mm 2591

[0033] The test steps are as follows:

[0034] Step 1: Preparation before the test, build the differential base station 4, and install the tractor gyroscope and trailer gyroscope at the corresponding positions, and determine a certain length of test road and the baseline on the test road, and store the position of the baseline in the differential base station. The equipment required is shown in Table 2.

[0035] Table 2 Equipment required during the test

[0036]

[0037] Since tire pressure and wind speed will affect the test results, tire pressure gauges and anemometers are used to ensure the consistency of test results. The ambient temperature, humidity, vehicle mass and center of mass must all meet relevant standard requirements, with the temperature between 0-40°C and humidity no greater than 95%, so a digital thermometer and hygrometer are required. During each test, the vehicle mass and center of mass must be within the specified error range, so a rollover test bench is required.

[0038] In the entire test, in order to reduce the interference of other factors, the conditions of the test road are shown in Table 3.

[0039] Table 3 Test roads

[0040]

[0041]

[0042] The second step is preheating and lane line drawing. The vehicle accelerates at no less than 4m / s 2 The equipment should be preheated by sudden acceleration or deceleration, figure 8 or serpentine movements, and the hot car should be driven for no less than 30 minutes and no less than 30 kilometers to warm up the tires and ensure normal lubrication of all components.

[0043] The third step is to conduct a test. The vehicle drives at a constant speed of 30kmn / h along the baseline on the test road for 600m. It should drive in a straight line for at least 80m before entering the test road. When reaching the starting end of the test road, the instantaneous speed should be guaranteed to be 30±2kmn / h. Then test and save the measured real-time data.

[0044] The fourth step is data processing and analysis. The vehicle driving trajectory is shown in the figure Figure 2 As shown, the data collection points are the data values ​​of the tractor gyroscope 7 and the trailer gyroscope 9 collected every 10 ms starting from the starting end of the test road, from Figure 2 The lateral position relationship between the trailer and the tractor can be clearly shown in the figure. The driving trajectory shows that the semi-trailer tractor is driving in a curve, so the swing amplitude of the articulated train can be obtained as follows: Figure 3 As shown, the swing amplitude is calculated by the following formula.

[0045] A i =Y 2i -Y 1i

[0046] Among them, i is the time the vehicle travels on the test road, Ai is the swing amplitude of the vehicle at time i, Y 2i Y is the distance that the center of the trailer rear axle is offset from the reference line at time i, 1i It is the distance that the center of the tractor's front axle is offset from the reference line.

[0047] After analysis, the maximum value is 104mm and the minimum value is -129mm, so the maximum swing amplitude is 129mm at this time.

[0048] Step 5: Repeat the test. Repeat steps 3 and 4 for 6 round trips on the test road to obtain 12 data. The 12 data are analyzed to obtain the results shown in Table 4.

[0049] Table 4 Test quantity analysis

[0050]

[0051] From Table 4, we can see that the average values ​​of the round trip data differ significantly, reaching 20%, and the relative standard deviations of the round trip data are 16.9% and 18.2% respectively.

[0052] Since there will be abnormal data, after judging and eliminating the abnormal data through the Grubbs criterion, the data processing structure obtained is shown in Table 5.

[0053] Table 5 Data processing results

[0054]

[0055]

[0056] Because the test results are close to the limit, affecting the compliance judgment, or the dispersion is large, it is necessary to conduct uncertainty analysis of the test results.

[0057] The Type A uncertainty is calculated as follows:

[0058] Standard Deviation

[0059] According to the discreteness of the test data, the experiment is required to test 6 times in each direction, for a total of 12 times, and m is 12, then the uncertainty of type A is

[0060] Calculation of Type B uncertainty:

[0061] The equipment testing accuracy is 20mm, which is uniformly distributed.

[0062]

[0063] The test result resolution is 1mm, which is uniformly distributed.

[0064]

[0065] The type B uncertainty is

[0066] The combined uncertainty of Type A uncertainty and Type B uncertainty is

[0067]

[0068] Take the coverage factor k = 2, the confidence probability is 95%, then the uncertainty

[0069] U=u C ×k=7.9×2=15.8

[0070] The maximum swing amplitude test result is: (95±16mm), k=2 (6 times each for the round trip, a total of 12 times).

Claims

1. A device for testing the swing amplitude of the rear axle center of a trailer relative to the front axle center of a tractor during straight-line driving, characterized in that: The invention comprises a tractor gyroscope (7) arranged at the center of a tractor front axle (6), a trailer gyroscope (9) arranged at the center of a trailer rear axle (8), and a reference line (1) arranged on a test road (5) and used as a reference for the tractor (2) to travel during the test. A differential base station (4) capable of acquiring the coordinate positions of the tractor gyroscope (7) and the trailer gyroscope (9) is built on one side outside the test road (5).

2. The device for testing the swing amplitude of the rear axle center of a trailer relative to the front axle center of a tractor when traveling in a straight line according to claim 1, characterized in that: The sampling frequency of the equipment in the differential base station (4) is not less than 100 Hz, the data delay time is not greater than 0.01 s, and the measurement accuracy is not greater than 20 mm.

3. The device for testing the swing amplitude of the rear axle center of a trailer relative to the front axle center of a tractor when traveling in a straight line according to claim 1, characterized in that: The differential base station (4) comprises a host computer and a receiver.

4. The device for testing the swing amplitude of the rear axle center of a trailer relative to the front axle center of a tractor during straight-line driving according to claim 1, characterized in that: The length of the test road is not less than 500m.

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