Electric trailer sliding test method

Abstract

The invention discloses an electric trailer sliding test method, which belongs to the technical field of automobile performance testing, and comprises the following steps: 1, preparing an electric trailer, a tractor and a conventional trailer; 2, the tractor and the electric trailer are combined into a first combination vehicle to reach a first state; 3, recording the sliding distance S1 of the first combination vehicle; 4, the tractor and the conventional trailer are combined into a second automobile train, and a second state consistent with the first state is achieved; 5, recording the sliding distance S2 of the second train; 6, carrying out the stowage of the simulation saddle transfer mass of the tractor as a third combination vehicle, and achieving a third state which is consistent with the tractor in the first state; 7, recording the sliding distance S3 of the third train; and 8, calculating and analyzing the relationship among S1, S2 and S3, and judging the sliding performance of the electric trailer. The rationality of the structure and control logic design of the electric trailer can be effectively measured, and a reliable and easy-to-operate test method is provided for sliding of the electric trailer.

Description

Technical Field

[0001] The present invention relates to the technical field of automotive performance testing, and particularly to a method for conducting a coasting test on an electric trailer. Background Art

[0002] With the global new energy vehicle industry entering a rapid development stage under long-term technological accumulation and market cultivation, the technical levels of core components such as batteries, motors, and intelligent control have been continuously improved, and the costs have decreased year by year, laying a foundation for the wide application of electrification technology. In the field of commercial vehicles, the full-life cycle fuel consumption of traditional energy vehicle trains (a combination of tractors and trailers) is as high as over 300,000 liters. The high energy consumption not only brings huge operating cost pressure but also faces severe challenges in emission reduction and carbon reduction. Therefore, the driving range and energy efficiency optimization of new energy vehicles have become the core indicators concerned by the industry. Against this background, domestic and foreign enterprises have begun to explore expanding mature new energy technologies to the trailer field and developing electric trailers with energy recovery and auxiliary drive functions. Such products can significantly reduce the overall energy consumption and CO2 emissions of vehicle trains through braking energy recovery, electrical energy storage under deceleration conditions, and power assistance during starting and climbing, thereby improving the economy and environmental friendliness of logistics transportation.

[0003] In automotive performance testing, the coasting performance is an important indicator for evaluating a vehicle's ability to travel by inertia without driving force, directly affecting fuel economy, driving smoothness, and safety. At the same time, it is also a basic test item for inspecting the technical state of the chassis. Conventional trailers, due to having no drive or energy recovery system and relying only on the power of the tractor for driving, have a simple mechanical structure, and their coasting performance is usually not affected by additional resistance. Therefore, no country's standard has put forward clear requirements for the coasting performance of trailers. However, the emergence of electric trailers has changed this situation: the built-in drive motor, energy recovery system, and electronic control device in them may introduce additional resistance moments or energy recovery interventions, thereby potentially interfering with the overall coasting performance of vehicle trains, but there is currently no corresponding test and determination method.

[0004] Aiming at the above problems, how to accurately evaluate the coasting performance of electric trailers is a technical problem that needs to be solved. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for conducting a coasting test on an electric trailer to solve the problems existing in the above-mentioned prior art. By connecting the tractor to an electric trailer and a conventional trailer respectively and simulating the transfer mass of the saddle for loading, and comparing the coasting distances, the rationality of the electric trailer's structure and control logic design can be effectively measured, providing a reliable and easy-to-operate test method for the coasting of electric trailers.

[0006] To achieve the above purpose, the present invention provides the following solutions:

[0007] The present invention provides a method for conducting a coasting test on an electric trailer, including the following steps:

[0008] Step 1: Prepare an electric trailer, a tractor, and a conventional trailer.

[0009] Step 2: Combine the tractor and the electric trailer into a first motor vehicle train, and through loading, make the first motor vehicle train reach a first state.

[0010] Step 3: Make the first motor vehicle train enter a coasting state, and record the coasting distance S1 of the first motor vehicle train from a set speed to a complete stop.

[0011] Step 4: After detaching the tractor from the electric trailer, combine it with the conventional trailer to form a second motor vehicle train, and through loading, make the second motor vehicle train reach a second state, and the second state is consistent with the first state.

[0012] Step 5: Make the second motor vehicle train enter a coasting state, and record the coasting distance S2 of the second motor vehicle train from a set speed to a complete stop.

[0013] Step 6: After detaching the tractor from the conventional trailer, simulate the transfer mass of the saddle for loading to form a third motor vehicle train, and through loading, make the third motor vehicle train reach a third state, and the state of the tractor in the third state is consistent with the state of the tractor in the first state.

[0014] Step 7: Make the third motor vehicle train enter a coasting state, and record the coasting distance S3 of the third motor vehicle train from a set speed to a complete stop.

[0015] Step 8: Calculate and analyze the relationship among S1, S2, and S3, and judge the coasting performance of the electric trailer.

[0016] In an embodiment, the conventional trailer and the electric trailer are consistent in terms of external dimensions, number of axles, tire model and condition, arrangement of kingpin and axles, maximum design axle load, and total mass design parameters.

[0017] In an embodiment, the requirements for the test site are as follows: The test is carried out on an asphalt road surface or a concrete road surface, the longitudinal slope of the test road surface does not exceed 0.1%, and the transverse slope does not exceed 3%.

[0018] In an embodiment, the requirements for the test environment are as follows: The relative humidity is less than 95%RH, the atmospheric temperature is 0°C to 40°C, the wind speed measured at a height of 1.6 m above the test ground is not greater than 3.0 m / s, and the test environment differences among the first motor vehicle train, the second motor vehicle train, and the third motor vehicle train do not exceed 10%.

[0019] In one embodiment, in step 2, in the first state, the total mass of the first articulated vehicle is made to reach the curb mass of the tractor + the curb mass of the electric trailer + 50% of the designed load mass of the electric trailer, and the axle load of the front axle of the tractor, the axle load of the rear axle of the tractor or the axle load of the rear two-axle group, and the axle load of the axle group of the electric trailer in the first state are tested and recorded.

[0020] In one embodiment, in step 4, the axle load of the front axle of the tractor, the axle load of the rear axle of the tractor or the axle load of the rear two-axle group in the second state is kept consistent with the axle load of the front axle of the tractor, the axle load of the rear axle of the tractor or the axle load of the rear two-axle group in the first state, and the axle load of the axle group of the conventional trailer in the second state is kept consistent with the axle load of the axle group of the electric trailer in the first state; in step 6, the axle load of the front axle of the tractor, the axle load of the rear axle of the tractor or the axle load of the rear two-axle group in the third state is kept consistent with the axle load of the front axle of the tractor, the axle load of the rear axle of the tractor or the axle load of the rear two-axle group in the first state.

[0021] In one embodiment, in steps 3, 5 and 7, first reach the initial speed and maintain a constant speed at the initial speed, then enter the coasting state, and record the coasting distance from the set speed to a complete stop. The initial speed is 53 km / h to 55 km / h, and the set speed is 50 km / h.

[0022] In one embodiment, in steps 3, 5 and 7, in each step, it is carried out three times back and forth, the paths of the back and forth are coincident, and the length difference in the same direction does not exceed 5%. The average value of six tests in each of the above steps is calculated to obtain S1, S2 and S3 respectively; if the difference between S1 and S2 exceeds 10%, that is, ∣(S1 - S2) / S1∣≥10%, it should be checked whether the auxiliary drive system of the electric trailer has played a role during the coasting test, and after eliminating the influencing factors, retest, and record the result of the retest as S1. If it is confirmed that the state of the electric trailer is normal, maintain the original S1 as the final record and make a note.

[0023] In one embodiment, in step 2, the following operations are performed on the first articulated vehicle in the first state: turn off the lighting device, all windows and ventilation devices, adjust the cold inflation pressure of the tires to the designed value, warm up the vehicle, drive at a constant speed of 50 km / h for 20 minutes, turn off all auxiliary drive or energy recovery functions, and when the tractor is in the coasting mode, the first articulated vehicle does not generate a driving or braking force for coasting.

[0024] In one embodiment, in step 8, calculate the influence factor a of the electric trailer on the coasting performance, a = (S1 - S3) / S3 × 100%; calculate the influence factor b of the auxiliary drive structure on the coasting performance of the trailer, b = (S1 - S2) / S1 × 100%; when S1 is greater than or equal to S3, a is non-negative, indicating that the electric trailer has no impact or has a positive impact on the road train combined with the tractor; when S1 is less than S3, a is negative, indicating that the electric trailer has a negative impact on the road train combined with the tractor; if a is negative and |b| ≥ 10%, it indicates that the coasting performance of the electric trailer is poor, and the relevant system design should be optimized.

[0025] The present invention has achieved the following technical effects compared with the prior art:

[0026] The present invention uses the tractor to be connected to the electric trailer and the conventional trailer respectively, and simulates the transfer mass of the saddle to carry out load distribution, and compares the coasting distances, so as to study the coasting performance of the electric trailer and the overall coasting performance of the combination of the electric trailer and the tractor into a road train. It can effectively measure the rationality of the structure and control logic design of the electric trailer, and provide a reliable and easy-to-operate test method for the coasting of the electric trailer, so as to ensure that the product will not generate additional resistance to the tractor due to unreasonable mechanical structure design or inaccurate control logic when applied in the market, thereby affecting the operation efficiency and reducing the energy efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0028] Figure 1 It is a schematic diagram of the first road train after the combination of the tractor and the electric trailer in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0030] The object of the present invention is to provide a method for the coasting test of an electric trailer to solve the problems existing in the above-mentioned prior art. By connecting a tractor to an electric trailer and a conventional trailer respectively and simulating the transfer mass of the saddle for load distribution, and comparing the coasting distances, the rationality of the structure and control logic design of the electric trailer can be effectively measured, providing a reliable and easy-to-operate test method for the coasting of the electric trailer.

[0031] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] The present invention mainly studies the coasting test of an electric trailer, and combines the matching characteristics of the electric trailer and the tractor to explore a test and verification method for the coasting performance of the electric trailer. The electric trailer is a product of the application of the latest research in recent years. For new technology applications and related vehicles, it is necessary to conduct a necessary inspection of the technical conditions of their chassis, drive system, etc. before carrying out function and performance tests. Since only M-class motor vehicles (M-class motor vehicles refer to vehicles with a certain power device and a specific vehicle structure, mechanically driven and capable of driving on the road. According to different functions and uses, M-class motor vehicles can be divided into multiple sub-categories) and N-class motor vehicles (N-class motor vehicles refer to non-cargo vehicles with a certain power device and a specific vehicle structure, mechanically driven and capable of driving on the road. According to different functions and uses, N-class motor vehicles can be divided into multiple sub-categories) were involved in products related to the drive system before the appearance of the electric trailer, the relevant coasting test methods only considered single motor vehicles and are not applicable to electric trailers and motor vehicle trains. It is necessary to consider practical and feasible technical routes and verification methods to ensure its operability.

[0033] Combined with Figure 1As shown, the self-structures and connection relationships of the electric trailer and the tractor are presented. The tractor is mechanically connected to the electric trailer and undertakes the functions of traction and main drive, including a fuel system, an engine, and a transmission. Among them, the fuel system supplies the main energy to the engine, the engine provides power to the transmission, and the power is provided to the running gear through the transmission. The electric trailer has an auxiliary drive function, including a power battery, an inverter, and a motor. Among them, the power battery is electrically connected to the inverter, the inverter is electrically connected to the motor, and the motor drives the wheels to rotate. The power battery can provide power for the operation of the motor, and the motor can also supply energy to the power battery in the reverse direction to achieve energy recovery. After the electric trailer and the tractor are combined into a road train, as a whole, it is more like a hybrid vehicle. If only the coasting of the tractor is considered, the coasting ability of the electric trailer is lack of assessment, and it is impossible to judge the coasting performance of the road train after combination. It is unknown whether there is a phenomenon that the resistance is too large due to the unreasonable design of the drive device on the electric trailer, which affects the energy consumption during the use of the road train, or whether there is an auxiliary driving force that does not conform to the driver's intention generated by the trailer during the coasting state due to the unreasonable control logic. If the coasting performance of the road train is tested as a whole, it actually masks the coasting performance of the tractor and the electric trailer respectively. Since the production entities of the current tractor and the electric trailer are separated, and they are actually purchased separately at the actual market application end and then combined for use, it means that the test results can only reflect the level of the test sample vehicle, and have limited guiding significance for the market use end and the judgment of the technical level of the tractor and the electric trailer.

[0034] The present invention provides a method for testing the coasting of an electric trailer, including the following contents:

[0035] Step 1: Prepare an electric trailer, a tractor, and a conventional trailer. The tractor is respectively adapted to the electric trailer and the conventional trailer. The conventional trailer is relatively close to the electric trailer in structure and has a good technical condition (when necessary, a comparative test with other conventional trailers is carried out to ensure a good state). Since the vehicle design of the electric trailer is a drive axle, which is different from the axle of the conventional trailer that only realizes the load-bearing function, the comparison of the test results of the electric trailer and the conventional trailer can measure the change in the coasting performance of the trailer brought by the electrified structure. Therefore, the test data of the conventional trailer can be used as a comparison benchmark; at the same time, select a suitable test site and a suitable test environment;

[0036] Step 2: Combine the tractor and the electric trailer into a first road train, and make the first road train reach a first state through loading (usually in a uniform loading manner). In the first state, the first road train has a suitable total mass and load, etc.;

[0037] Step 3: Put the first articulated vehicle into the coasting state, record the coasting distance S1 of the first articulated vehicle from the set speed to a complete stop. This can be done multiple times and the average value can be taken. The vehicle speed and the driving distance can be recorded by a GPS testing device, which is installed on the tractor.

[0038] Step 4: After detaching the tractor from the electric trailer, combine it with a conventional trailer to form a second articulated vehicle. By loading (usually in a uniform loading manner), make the second articulated vehicle reach the second state. In the second state, the second articulated vehicle has an appropriate total mass, load, etc., and the second state is the same as the first state.

[0039] Step 6: After detaching the tractor from the conventional trailer, simulate the saddle transfer mass for loading to form a third articulated vehicle. Usually, the saddle is removed and a small cargo box is installed. Of course, other loading methods can also be used to make the third articulated vehicle reach the third state through loading. In the third state, the second articulated vehicle has an appropriate total mass, load, etc., and the state of the tractor in the third state is the same as the state of the tractor in the first state.

[0040] Step 6: After detaching the tractor from the conventional trailer, simulate the saddle transfer mass for loading to form a third articulated vehicle. Usually, the saddle is removed and a small cargo box is installed. Of course, other loading methods can also be used to make the third articulated vehicle reach the third state through loading. In the third state, the second articulated vehicle has an appropriate total mass, load, etc., and the state of the tractor in the third state is the same as the state of the tractor in the first state.

[0041] Step 7: Put the third articulated vehicle into the coasting state, record the coasting distance S3 of the third articulated vehicle from the set speed to a complete stop. This can be done multiple times and the average value can be taken. The vehicle speed and the driving distance can be recorded by a GPS testing device, which is installed on the tractor.

[0042] Step 8: Calculate and analyze the relationship among S1, S2, and S3 to judge the coasting performance of the electric trailer. Since the coasting results of the tractor under two states, i.e., when it is loaded alone and when it is combined with an articulated vehicle and uniformly loaded, are affected by factors such as inertia, rolling resistance, and the change in the distribution of coasting forces, they do not have the significance of direct comparison. However, for the same tractor, when two trailers (electric trailer and conventional trailer) with similar matching states are under similar testing conditions and various control factors such as loading are close, they should show similar trends. If there are deviations or large deviations (the data comparison of S1, S2, and S3), it proves that the electric trailer needs to be adjusted in terms of system or structural design.

[0043] In one embodiment, when it is said that the structure of a conventional trailer is relatively close to that of an electric trailer, it means that the design parameters such as the external dimensions, number of axles, tire models and conditions, arrangement of kingpins and axles, maximum design axle load and gross mass of the conventional trailer and the electric trailer are the same. As those skilled in the art can understand, the so-called "same" here should be maintained within an appropriate error range (referring to that there can be certain errors in dimensions, conditions, mass, etc., while other parameters such as the number of axles and tire models should be the same), and it does not mean exactly the same.

[0044] In one embodiment, the requirements for the test site are as follows: The test is carried out on an asphalt road surface or a concrete road surface. The longitudinal slope of the test road surface does not exceed 0.1%, and the transverse slope does not exceed 3%. The selected road surface should be hard, straight, clean, dry and long enough.

[0045] In one embodiment, the requirements for the test environment are as follows: The relative humidity is less than 95%RH, the atmospheric temperature is 0°C to 40°C, the wind speed measured 1.6 m above the test ground is not greater than 3.0 m / s, and the difference in the test environment among the first articulated vehicle, the second articulated vehicle and the third articulated vehicle does not exceed 10%.

[0046] In one embodiment, in step 2, the electric trailer is evenly loaded to reach the first state. In the first state, the gross mass of the first articulated vehicle reaches the curb mass of the tractor + the curb mass of the electric trailer + 50% of the designed load mass of the electric trailer, and the front axle load of the tractor, the rear axle load of the tractor or the rear two-axle group load, and the axle group load of the electric trailer in the first state are tested and recorded.

[0047] In one embodiment, in step 4, the front axle load of the tractor, the rear axle load of the tractor or the rear two-axle group load in the second state is the same as that in the first state, and the axle group load of the conventional trailer in the second state is the same as that of the electric trailer in the first state; in step 6, the front axle load of the tractor, the rear axle load of the tractor or the rear two-axle group load in the third state is the same as that in the first state.

[0048] In one embodiment, in steps 3, 5 and 7, first reach the initial speed and maintain a constant speed at the initial speed, and then enter the coasting state. Record the coasting distance from the set speed to a complete stop. The value of the initial speed is generally greater than the value of the set speed, that is, first reach a higher vehicle speed, drive stably, and then enter the coasting state. In this example, the initial speed is 53 km / h to 55 km / h, and the set speed is 50 km / h.

[0049] In one embodiment, in steps 3, 5, and 7, in each of these steps, the process is repeated three times back and forth, the paths of the back-and-forth movement coincide, and the length difference in the same direction does not exceed 5%. The average value of six tests is calculated for each of the above steps, obtaining S1, S2, and S3 respectively; if the difference between S1 and S2 exceeds 10%, that is:

[0050] |(S1 - S2) / S1| ≥ 10%;

[0051] It should be checked whether the electric trailer auxiliary drive system has played a role during the coasting test, and after eliminating the influencing factors, retest. Record the result of the retest as S1. If it is confirmed that the state of the electric trailer is normal, maintain the original S1 as the final record and make a note for explanation.

[0052] In one embodiment, in step 2, the following operations are performed on the condition of the first motor vehicle train in the first state: turn off the lighting device, all windows, and the ventilation device, adjust the cold inflation pressure of the tires to the designed value, warm up the vehicle, drive at a constant speed of 50 km / h for 20 minutes, turn off all auxiliary drive or energy recovery functions, and when the tractor is in the coasting mode, the first motor vehicle train does not generate a driving force or a force to prevent coasting.

[0053] In one embodiment, in step 8, calculate the influence factor of the electric trailer on the coasting performance:

[0054] a = (S1 - S3) / S3 × 100%;

[0055] Calculate the influence factor of the auxiliary drive structure on the coasting performance of the trailer:

[0056] b = (S1 - S2) / S1 × 100%;

[0057] When S1 is greater than or equal to S3, a is non-negative, indicating that the electric trailer has no influence or has a positive influence on the motor vehicle train combined with the tractor;

[0058] When S1 is less than S3, a is negative, indicating that the electric trailer has a negative influence on the motor vehicle train combined with the tractor;

[0059] If a is negative and |b| ≥ 10%, it indicates that the coasting performance of the electric trailer is poor, and the relevant system design should be optimized.

[0060] The present invention provides the following embodiments:

[0061] 1. Select suitable test vehicles: an electric trailer, a tractor suitable for the electric trailer, and a conventional trailer that is structurally close to the electric trailer and in good technical condition. Among them, being structurally close to the electric trailer means that design parameters such as the external dimensions, the number of axles, the tire model and condition (tread depth), the arrangement of the drawbar and axles, the maximum design axle load and the total mass are the same or close. To ensure the good technical condition of the conventional trailer, comparative tests with other conventional trailers may be necessary when required.

[0062] 2. Select suitable test sites: Conduct tests on a hard, straight, clean, dry, and sufficiently long asphalt or concrete road surface. The longitudinal slope of the test road surface should not exceed 0.1%, and the transverse slope should not exceed 3%.

[0063] 3. Select suitable test environments. The wind speed, humidity, and temperature should meet the following requirements, and the differences when the tractor, the combination of the tractor and the conventional trailer, and the combination of the tractor and the electric trailer are no more than 10%: the relative humidity should be less than 95%RH, the atmospheric temperature should be 0°C to 40°C, and the wind speed measured 1.6 m above the test ground should not be greater than 3.0 m / s.

[0064] 4. Install a GPS test device on the tractor that can record the vehicle speed and driving distance in real time.

[0065] 5. Combine the tractor and the electric trailer into the first articulated vehicle, and evenly load the electric trailer so that the total mass of the first articulated vehicle reaches the tractor's curb mass + the electric trailer's curb mass + 50% of the electric trailer's design load mass, reaching the first state. Test and record the front axle load of the tractor, the rear axle load of the tractor (or the rear two-axle group load), and the axle group load of the electric trailer after loading in the first state.

[0066] 6. Complete the vehicle condition preparation of the first articulated vehicle in the first state: Turn off the lighting device, all windows, and ventilation devices. Adjust the cold inflation pressure of the tires to the design value. Warm up the vehicle and drive at a constant speed of 50 km / h for 20 minutes. Turn off all auxiliary drive or energy recovery functions so that when the tractor is in the coasting mode, the first articulated vehicle does not generate a driving or braking force to prevent coasting.

[0067] 7. The first articulated vehicle maintains a constant speed of 55 km / h (error -2 km / h to 0), release the accelerator pedal, and make the first articulated vehicle enter the coasting state (for manual transmission vehicles, shift the transmission gear to neutral and release the clutch pedal; for automatic transmission vehicles, shift the transmission gear to N or switch the vehicle to the coasting mode).

[0068] 8. During the coasting process, the first articulated vehicle should drive in a straight line and avoid operating the accelerator pedal and the brake pedal.

[0069] 9. Record the coasting distance S of the first articulated vehicle from 50 km / h to a complete stop.

[0070] 10. Conduct the test at least three times for each round trip. The paths of the round trips should overlap as much as possible, and the difference in S in the same direction should not exceed 5%. Calculate the average value of the 6 tests and denote it as S1.

[0071] 11. Keep the tractor in the same state. After detaching from the electric trailer, recombine it with a conventional trailer to obtain the second articulated vehicle. Uniformly load the conventional trailer to reach the second state, so that the front axle load of the tractor, the rear axle load of the tractor (or the load of the rear two - axle group), and the axle group load of the electric trailer in the second state are consistent with those in the first state.

[0072] 12. The vehicle condition preparation of the second articulated vehicle in the second state should be the same as that in the first state. If replacing the electric trailer with a conventional trailer takes a long time for recombination and loading, the vehicle should be reheated to ensure that the test vehicle is at the normal driving temperature.

[0073] 13. Keep the vehicle driving at a constant speed of 55 km / h (with an error of - 2 km / h to 0). Release the accelerator pedal to make the vehicle enter the coasting state (for a vehicle with a manual transmission, shift the transmission to neutral and release the clutch pedal; for a vehicle with an automatic transmission, shift the transmission to N or switch the vehicle to the coasting mode).

[0074] 14. During the coasting process, the second articulated vehicle should drive in a straight line, avoiding operating the accelerator pedal and the brake pedal.

[0075] 15. Record the coasting distance S of the second articulated vehicle from 50 km / h to a complete stop.

[0076] 16. Conduct the test at least three times for each round trip. The paths of the round trips should overlap as much as possible, and the difference in S in the same direction should not exceed 5%. Calculate the average value of the 6 tests and denote it as S2.

[0077] 17. Keep the tractor in the same state. Detach it from the conventional trailer and simulate the transfer mass of the saddle to load it, obtaining the third articulated vehicle. During loading, usually remove the saddle and install a small cargo box. The height, width, and length of the small cargo box do not exceed the vehicle's external contour and do not increase the vehicle's frontal area, reaching the third state, so that the front axle load of the tractor and the rear axle load of the tractor (or the load of the rear two - axle group) in the third state are consistent with those in the first state.

[0078] 18. The vehicle condition preparation of the tractor in the third state should be the same as that of the tractor in the first state. Usually, this process takes a long time. After completing the vehicle preparation, the vehicle should be reheated to ensure that the test vehicle is at the normal driving temperature.

[0079] 19. The third motor vehicle train travels at a constant speed of 55 km / h (with an error of -2 km / h to 0), release the accelerator pedal to make the vehicle enter the coasting state (for a vehicle with a manual transmission, shift the transmission gear to neutral and release the clutch pedal; for a vehicle with an automatic transmission, shift the transmission gear to N or switch the vehicle to the coasting mode).

[0080] 20. During the coasting process, the third motor vehicle train should travel in a straight line and avoid operating the accelerator pedal and the brake pedal.

[0081] 21. Record the coasting distance S of the third motor vehicle train from 50 km / h to a complete stop.

[0082] 22. The test should be carried out at least three times for each round trip. The paths of the round trips should coincide as much as possible, and the difference in S in the same direction should not exceed 5%. Calculate the average value of the 6 tests and record it as S3.

[0083] 23. S1 and S2 should be basically close. If the difference between S1 and S2 exceeds 10%, that is:

[0084] ∣(S1 - S2) / S1∣≥10%;

[0085] It should be checked whether the electric trailer auxiliary drive system has played a role (generating auxiliary drive or energy recovery) during the coasting test, and after eliminating the influencing factors, retest, and record the result of the retest as S1. If it is confirmed that the state of the electric trailer is normal, maintain the original S1 as the final record and make a note.

[0086] 24. Calculate the influence factor of the electric trailer on the coasting performance:

[0087] a = (S1 - S3) / S3 × 100%;

[0088] Calculate the influence factor of the auxiliary drive structure on the coasting performance of the trailer:

[0089] b = (S1 - S2) / S1 × 100%;

[0090] When S1 is greater than or equal to S3, a is non - negative, indicating that the electric trailer has no influence or has a positive influence on the motor vehicle train combined with the tractor;

[0091] When S1 is less than S3, a is negative, indicating that the electric trailer has a negative influence on the motor vehicle train combined with the tractor;

[0092] If a is negative and ∣b∣≥10%, it indicates that the coasting performance of the electric trailer is poor, and the relevant system design should be optimized.

[0093] In the present invention, specific examples are used to illustrate the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation on the present invention.

Claims

1. An electric trailer coasting test method, characterized in that, It includes the following contents: Step 1: Prepare an electric trailer, a tractor, and a conventional trailer; Step 2: Combine the tractor and the electric trailer into a first motor train, and make the first motor train reach a first state through loading; Step 3: Make the first motor train enter a coasting state, and record the coasting distance S1 of the first motor train from a set speed to a complete stop; Step 4: After detaching the tractor from the electric trailer, combine it with the conventional trailer to form a second motor train, and make the second motor train reach a second state through loading, where the second state is consistent with the first state; Step 5: Make the second motor train enter a coasting state, and record the coasting distance S2 of the second motor train from a set speed to a complete stop; Step 6: After detaching the tractor from the conventional trailer, simulate the saddle transfer mass for loading to form a third motor train, and make the third motor train reach a third state through loading, where the state of the tractor in the third state is consistent with the state of the tractor in the first state; Step 7: Make the third motor train enter a coasting state, and record the coasting distance S3 of the third motor train from a set speed to a complete stop; Step 8: Calculate and analyze the relationship among S1, S2, and S3 to judge the coasting performance of the electric trailer.

2. The electric trailer coasting test method according to claim 1, characterized in that: The conventional trailer and the electric trailer are consistent in terms of external dimensions, number of axles, tire models and states, arrangement of kingpins and axles, maximum designed axle load, and total mass design parameters.

3. The electric trailer coasting test method according to claim 1, characterized in that: The requirements for the test site are as follows: The test is carried out on an asphalt road surface or a concrete road surface, the longitudinal slope of the test road surface does not exceed 0.1%, and the transverse slope does not exceed 3%.

4. The electric trailer coasting test method according to claim 1, characterized in that: The requirements for the test environment are as follows: The relative humidity is less than 95%RH, the atmospheric temperature is 0°C to 40°C, the wind speed measured 1.6 m above the test ground is not greater than 3.0 m / s, and the test environment differences of the first motor train, the second motor train, and the third motor train do not exceed 10%.

5. The electric trailer coasting test method according to claim 1, wherein: In Step 2, in the first state, make the total mass of the first motor train reach the tractor curb mass + the electric trailer curb mass + 50% of the electric trailer designed load mass, and test and record the front axle load of the tractor, the rear axle load or the rear two-axle group load of the tractor, and the axle group load of the electric trailer in the first state.

6. The electric trailer coasting test method according to claim 5, characterized in that: In Step 4, the front axle load of the tractor, the rear axle load or the rear two-axle group load of the tractor in the second state is consistent with the front axle load of the tractor, the rear axle load or the rear two-axle group load of the tractor in the first state, and the axle group load of the conventional trailer in the second state is consistent with the axle group load of the electric trailer in the first state; in Step 6, the front axle load of the tractor, the rear axle load or the rear two-axle group load of the tractor in the third state is consistent with the front axle load of the tractor, the rear axle load or the rear two-axle group load of the tractor in the first state.

7. The electric trailer coasting test method according to claim 1, characterized in that: In Step 3, Step 5, and Step 7, first reach an initial speed, maintain a constant speed at the initial speed, and then enter a coasting state, and record the coasting distance from the set speed to a complete stop. The initial speed is 53 km / h to 55 km / h, and the set speed is 50 km / h.

8. The electric trailer coasting test method according to claim 1, wherein: In Step 3, Step 5, and Step 7, in each of these steps, perform three round trips. The paths of the round trips coincide, and the length difference in the same direction does not exceed 5%. Calculate the average value of six tests for each of the above steps, obtaining S1, S2, and S3 respectively. If the difference between S1 and S2 exceeds 10%, that is, ∣(S1 - S2) / S1∣≥10%, it is necessary to check whether the electric trailer auxiliary drive system has played a role during the coasting test, and retest after eliminating the influencing factors. Record the result of the retest as S1. If it is confirmed that the state of the electric trailer is normal, maintain the original S1 as the final record and make a note.

9. The electric trailer coasting test method according to claim 1, characterized in that: In Step 2, perform the following operations on the first motor vehicle train in the first state: Turn off the lighting device, all windows, and the ventilation device, adjust the cold inflation pressure of the tires to the design value, warm up the vehicle, drive at a constant speed of 50 km / h for 20 minutes, turn off all auxiliary drive or energy recovery functions, and when the tractor is in the coasting mode, the first motor vehicle train does not generate a driving or retarding force for coasting.

10. The electric trailer coasting test method according to claim 1, characterized in that: In Step 8, calculate the influence factor a of the electric trailer on the coasting performance: a = (S1 - S3) / S3×100%; calculate the influence factor b of the auxiliary drive structure on the coasting performance of the trailer: b = (S1 - S2) / S1×100%; when S1 is greater than or equal to S3, a is non - negative, indicating that the electric trailer has no impact or has a positive impact on the motor vehicle train combined with the tractor; when S1 is less than S3, a is negative, indicating that the electric trailer has a negative impact on the motor vehicle train combined with the tractor; if a is negative and ∣b∣≥10%, it indicates that the coasting performance of the electric trailer is poor, and the relevant system design should be optimized.

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