A method for testing tire cornering characteristics under dynamic load

Abstract

The present invention relates to a method for testing tire cornering characteristics under dynamic load. It includes dynamic step condition test and identification, and dynamic load cornering characteristic test; the dynamic step condition test and identification is to perform dimensionless data processing and model identification of setting parameters based on the lateral relaxation length identification result to meet the expression of tire lateral transient characteristics; the dynamic load cornering characteristic test is to introduce dynamic load variables on the basis of the original discrete sideslip angle test, and achieve the purpose of completing the tire dynamic load cornering characteristic test with a smaller number of tests by changing the input of discrete frequency, and summarize the data processing and expression method; the present invention performs testing and data accumulation through standardized test methods to obtain tire cornering characteristics under dynamic excitation. It solves the problem that the influence of dynamic load on cornering characteristics cannot be accurately expressed in the prior art.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile lateral dynamics and relates to a tire side slip characteristic test method under dynamic load. Background Art

[0002] In the field of vehicle handling stability research, accurate testing and modeling have always been the focus of research. As the only contact part between the vehicle and the road, the tire's cornering characteristics have a very important impact on the vehicle's handling stability. At present, the research on tire cornering characteristics (steady state / quasi-steady state / transient), whether theoretical research or characteristic testing, is carried out under the action of a constant vertical load. However, when the car is moving at high speed, due to excitations such as undulations and bumps on the road surface, vertical vibrations will inevitably occur, which in turn causes a drastic change in the wheel load in the vertical direction, causing large fluctuations in the actual dynamic performance of the tire.

[0003] Under the excitation of dynamic vertical load, the lateral force of the tire will fluctuate, making the lateral stability and dynamic response of the vehicle worse. Therefore, it is very important to express the tire's cornering characteristics under the excitation of dynamic vertical load. Due to the lack of theoretical research and experimental data support, the influence of dynamic load on tire cornering characteristics has not been well studied.

[0004] Differences from the paper "Study on Tire Dynamic Loads under Single and Double Rut Excitation":

[0005] The paper studies the dynamic load characteristics of truck tires through the input of different road models, which is different from the test proposed in this paper through the superposition of sinusoidal loads of different frequencies. The dynamic load characteristics analysis on the vehicle is obtained indirectly, and the environmental factors and noise are very large, so effective modeling data cannot be obtained. The method of this patent can be tested on laboratory test equipment, controlling a single factor variable to study the dynamic load characteristics of tires, and more accurately generating modeling data for the dynamic load model.

[0006] Differences from the paper "Theoretical and Experimental Study on Tire Cornering Characteristics under Dynamic Loads":

[0007] This paper mainly focuses on the modeling problem of tire dynamic load side deviation. In essence, it uses a semi-empirical modeling method and only expresses the transient part. This patent also models the transient part and uses the physical model of spring damping to identify parameters, which is very different from the above paper.

[0008] The side slip dynamic load test method mentioned in the above paper is based on the low-speed flat plate six-component force. Due to the limitation of its equipment capacity, the test used is still for the transient characteristics of side slip. This patent uses a high-speed six-component tire test equipment with stronger test capabilities. The patent introduces the dynamic load characteristic test method under variable frequency and the data processing and analysis process. Compared with the expression of tire dynamic load characteristics, this method combines transient and dynamic, and has higher expression accuracy and more comprehensive expression.

[0009] Difference analysis from the paper "Analysis of Dynamic Load Characteristics of Heavy-Duty Vehicle Tires under Non-Stationary Driving Conditions":

[0010] The above paper uses a three-degree-of-freedom vehicle model to study the additional dynamic load of the tire. The method used is relatively simple, approximate to estimation, and has low accuracy. It is very different from the patent's method of obtaining the dynamic load characteristics of the tire through testing.

[0011] Patent document CN103278339B relates to a tire lateral force estimation method, comprising the following steps: 1) setting a tire lateral force estimation system including a wheel center longitudinal velocity sensor, a road adhesion coefficient sensor, a tire vertical force sensor, a tire side slip angle sensor, a tire slip rate sensor and a lateral force estimation module; 2) the lateral force estimation module estimates the quasi-static lateral force value of the tire according to the collected tire slip rate value, tire vertical force value, tire side slip angle and road adhesion coefficient value; 3) establishing a dynamic tire model according to the relationship between the dynamic lateral force of the tire and the quasi-static lateral force, the lateral force estimation module corrects the tire quasi-static lateral force value estimated in step 2) according to the collected wheel center longitudinal velocity and through the dynamic tire model to obtain a dynamic tire lateral force value; 4) sending the dynamic tire lateral force value obtained in step 3) to the vehicle controller for controlling and monitoring the vehicle. The present invention can be widely used in real-time estimation of tire lateral force.

[0012] Patent document CN103353402A relates to a multi-condition tire mechanical property test vehicle and test method, including 4 electric wheel motion units connected to the vehicle chassis through steering brackets, a control console, a battery, a non-contact speed sensor, an inertia test unit arranged on the vehicle chassis, and a weight block arranged on the vehicle chassis by adjusting the slide, wherein each electric wheel motion unit comprises: a wheel hub motor, a steering servo motor, a wheel steering angle sensor, a tire six-component force sensor, a tire connection plate of the tested tire and a wheel bracket; the wheel steering angle sensor, the tire six-component force sensor, the non-contact speed sensor, and the inertia test unit are respectively connected to the central controller in the control console through data lines to realize the measurement data collection of the tire steering angle and six-component force and the longitudinal acceleration, lateral acceleration and yaw angular velocity of the vehicle. It can realize the simulation test of multiple working conditions such as driving, braking, rolling resistance, side slip, side slip / longitudinal slip combination of tires.

[0013] The above patents have low relevance to this application. Summary of the invention

[0014] The technical problem to be solved by the present invention is to overcome the problem in the prior art that the influence of dynamic load on cornering characteristics cannot be accurately expressed, and a method for testing cornering characteristics of tires under dynamic load is provided.

[0015] The basis of research theory is the accumulation of test data. The present invention proposes a test method for cornering characteristics under dynamic load, aiming to obtain the tire cornering characteristics under dynamic excitation through testing and data accumulation using a standardized test method.

[0016] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0017] In order to solve the above technical problems, the present invention is implemented by adopting the following technical solutions:

[0018] A method for testing tire cornering characteristics under dynamic load, including dynamic step condition testing and identification, and dynamic load cornering characteristics testing;

[0019] The dynamic step condition test and identification is to perform dimensionless data processing and model identification of setting parameters based on the lateral relaxation length identification result to meet the expression of the lateral transient characteristics of the tire;

[0020] The dynamic load cornering characteristic test introduces the dynamic load variable on the basis of the original discrete cornering angle test, and achieves the purpose of completing the dynamic load cornering characteristic test of the tire with fewer tests by changing the input of discrete frequency, and summarizes the data processing and expression methods.

[0021] Furthermore, the dynamic step condition test and identification specifically includes:

[0022] Dynamic step condition test in linear and nonlinear regions;

[0023] Identification and dimensionless treatment of lateral relaxation length parameters;

[0024] Parameter identification of nonlinear relaxation length model.

[0025] Furthermore, the linear region and nonlinear region dynamic step condition test specifically includes:

[0026] Set working conditions: test load, slip angle, road speed;

[0027] Collect the required signals and draw a curve of the distance traveled by the tire and the process of lateral force establishment.

[0028] Furthermore, the lateral relaxation length parameter identification and dimensionless processing specifically include:

[0029] The lateral relaxation lengths under different loads are dimensionless, and the relaxation length under the standard load is set to 1, and the remaining relaxation lengths are calculated according to the ratio.

[0030] Furthermore, the nonlinear relaxation length model parameter identification specifically includes:

[0031] The tread elastic force model is equivalent to the connection of two parts ① and ②, ① is a group of parallel spring damping units, and ② is a group of series spring damping units to express the nonlinear characteristics of non-constant relaxation length.

[0032] Furthermore, the dynamic load side deviation characteristic test specifically includes:

[0033] Set working conditions: set the slip angle to 1 degree and 6 degrees, and conduct two tests; set the road speed to 5 km / h; set the vertical load loading mode to sine; set the loading frequency to 0.1 Hz, 0.5 Hz, 1 Hz, 2 Hz, 4 Hz, 6 Hz, 8 Hz and 16 Hz in sequence;

[0034] The relationship curves of lateral force, self-aligning moment and vertical force are output respectively.

[0035] A method for testing tire cornering characteristics under dynamic load, also includes test curve drawing and test effect comparison: in addition to the conventional cornering lateral force versus slip angle curve, it is also necessary to increase the frequency of independent variable factors, which respectively express the dynamic load curves of the tire in the linear and nonlinear regions.

[0036] Furthermore, before the dynamic step condition test and identification, pre-test preparation work is done;

[0037] Install the tire-rim assembly on the tire six-component force test bench, adjust the tire pressure and start the six-component force test bench.

[0038] Furthermore, the preparatory work before the test specifically includes: conducting a test run on the tire to eliminate stress before the formal test; setting a test run procedure, that is, the tire runs at a speed from a low speed of 20km / h to a high speed of 120km / h for 10 minutes under rated load, followed by a 1-minute reciprocating motion with a small side slip angle of -1° to 1° to ensure uniform heat generation of the tire and eliminate internal stress of the tire.; Subsequently, the tire is cooled by applying a small load of 500N and a small speed of 30km / h to cool the tire until the tread temperature meets the requirement of 30℃-35℃.

[0039] Furthermore, the working conditions in the dynamic step working condition tests in the linear region and the nonlinear region are set as follows: the test loads are 10%, 40%, 70% and 100%; the sideslip angles are set to 1 degree and 6 degrees; and the road speed is set to 5 km / h.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] The present invention proposes a test method for cornering characteristics under dynamic load, which aims to obtain the tire cornering characteristics under dynamic excitation through standardized test methods and data accumulation. This solves the problem that the prior art cannot accurately express the influence of dynamic load on cornering characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The present invention will be further described below in conjunction with the accompanying drawings:

[0043] Figure 1 This is a flow chart of the tire cornering characteristics test under dynamic loading;

[0044] Figure 2 This is a flow chart for dynamic step condition testing and identification;

[0045] Figure 3a This is the result diagram of the side slip angle step test in the linear region;

[0046] Figure 3bThis is the side slip angle step test result diagram in the nonlinear region;

[0047] Figure 4 This is a schematic diagram of the identification model structure;

[0048] Figure 5 This is the identification result diagram of the non-constant relaxation length model;

[0049] Figure 6 This is the flow chart of the lateral dynamic load test;

[0050] Figure 7 This is the test result diagram of the lateral deflection characteristics under dynamic load in the linear region;

[0051] Figure 8 This is the test result diagram of the lateral deflection characteristics under dynamic loading in the nonlinear region. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical scheme and advantages of the implementation of the present invention clearer, the technical scheme in the embodiment of the present invention will be described in more detail below in conjunction with the drawings in the embodiment of the present invention. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of the present invention, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limitations on the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The embodiments of the present invention are described in detail below in conjunction with the drawings.

[0053] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the scope of protection of the present invention.

[0054] The present invention is described in detail below in conjunction with the accompanying drawings:

[0055] The present invention proposes a test method based on the tire's cornering characteristics under dynamic load, which mainly includes the test of the transient and dynamic characteristics of the tire cornering condition, wherein the test of each part includes two parts, the linear region and the nonlinear region, and proposes a more comprehensive test method for the cornering characteristics under dynamic load. The flow chart of the test method is as follows Figure 1 As shown, the specific operation process is divided into the following 4 steps.

[0056] 1. Preparation before the test: Install the tire-rim assembly on the tire six-component force test bench, adjust the tire pressure and start the six-component force test bench. Since the residual and concentrated stresses of the tire during the manufacturing and molding process have not been completely eliminated, it is advisable to test the tire to eliminate the stress before the formal test. Set the test run program, that is, the tire runs from low speed (20km / h) to high speed (120km / h) for 10 minutes under the rated load, followed by 1 minute of reciprocating motion at a small side slip angle (-1°~1°) to ensure uniform heat generation of the tire and eliminate the internal stress of the tire. The tread temperature rise caused by heat generation will affect the test results of the side slip stiffness, so the tire needs to be cooled later. That is, apply a small load (500N) and a small speed (30km / h) to cool the tire until the tread temperature meets the requirements (30℃-35℃).

[0057] 2. Dynamic step condition test and identification: Since the lateral force of the tire is always in loading / unloading under dynamic loading (the vertical load of the tire changes), there is a process of building up the lateral force of the tire. Therefore, the side slip characteristic test under dynamic load loading first includes the transient building process test of the lateral force of the tire, that is, the relaxation length test, which is specifically divided into two parts: test and identification, such as Figure 2 shown.

[0058] Linear / non-linear dynamic step condition test:

[0059] Set working conditions: test load is 10%, 40%, 70% and 100% etc.; side slip angle is set to 1deg / 6deg; set road speed to 5km / h.

[0060] Collect the required signals and draw a curve of the distance traveled by the tire and the process of lateral force establishment. The results are as follows: Figure 3a , Figure 3b shown.

[0061] Identification and dimensionless processing of lateral relaxation length parameters: The lateral relaxation length is a parameter of the lateral force establishment process. It itself represents the distance traveled when the tire establishes a complete lateral force. It is represented by the value of the horizontal axis in the stable state on the curve. The lateral relaxation length under different loads is dimensionlessly processed, that is, the relaxation length under the standard load is set to 1, and the remaining relaxation lengths are calculated as relative values.

[0062] Nonlinear relaxation length model parameter identification: Model structure diagram as shown in Figure 4 As shown in the figure, the tread elastic force model is equivalent to the connection of two parts ① and ②, ① is a set of parallel spring damping units, ② is a set of series spring damping units, to express the nonlinear characteristics of non-constant relaxation length. The identification results are shown in Figure 5 shown.

[0063] 3. Dynamic load lateral deflection characteristic test:

[0064] The specific test process is as follows Figure 6 As shown in the figure, the working conditions are set as follows: the slip angle is set to 1deg / 6deg (two tests); the road speed is set to 5km / h; the vertical load loading mode is set to sine; the loading frequency is set to 0.1Hz, 0.5Hz, 1Hz, 2Hz, 4Hz, 6Hz, 8Hz and 16Hz in sequence; the load loading range is as large as possible according to the equipment capacity. The relationship curves between the lateral force / righting moment and the vertical force are output respectively.

[0065] 4. Test curve drawing and test effect comparison: In addition to the conventional side slip force versus side slip angle curve, it is also necessary to increase the frequency of the independent variable factor, so the following is drawn: Figure 7 , Figure 8 series of curves.

[0066] Figure 7 and Figure 8 They respectively express the dynamic load curves of the tire in the linear region and the nonlinear region. The figure expresses the relationship between the tire lateral force (x-axis) and the tire vertical load (y-axis) / frequency.

[0067] The present invention proposes a method for testing tire cornering characteristics under dynamic load, which specifically includes four parts: pre-test preparation, dynamic step condition test and identification, cornering dynamic load characteristic test, and test curve drawing and test effect comparison. The method mainly divides the dynamic load cornering characteristic test and data processing into two parts, transient and dynamic, and performs them separately.

[0068] The dynamic step condition test is based on the lateral relaxation length identification results, and performs dimensionless data processing and model identification of setting parameters to meet the expression of the tire's lateral transient characteristics.

[0069] The dynamic load cornering characteristic test is a new test method proposed in this patent. The key point is to introduce the dynamic load variable on the basis of the original discrete cornering angle test. By changing the input of discrete frequency, the purpose of completing the dynamic load cornering characteristic test of the tire can be achieved with fewer tests. The data processing and expression methods are summarized.

[0070] The above is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any modification, equivalent replacement and improvement made by any person skilled in the art within the technical scope disclosed by the present invention and within the spirit and principle of the present invention shall be covered within the protection scope of the present invention. At the same time, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

Claims

1. A method for testing tire cornering characteristics under dynamic load, characterized in that: Including dynamic step condition test and identification, dynamic load side deviation characteristic test; The dynamic step condition test and identification is to perform dimensionless data processing and model identification of setting parameters based on the lateral relaxation length identification result to meet the expression of the lateral transient characteristics of the tire; The dynamic load cornering characteristic test introduces the dynamic load variable on the basis of the original discrete cornering angle test, and achieves the purpose of completing the tire dynamic load cornering characteristic test with fewer test times by changing the input of discrete frequency, and summarizes the data processing and expression methods; The dynamic step condition test and identification specifically includes: Dynamic step condition test in linear and nonlinear regions; Identification and dimensionless treatment of lateral relaxation length parameters; Nonlinear relaxation length model parameter identification; The linear region and nonlinear region dynamic step condition test specifically includes: Set working conditions: test load, slip angle, road speed; Collect the required signals and draw a curve of the distance traveled by the tire and the process of establishing the lateral force; The lateral relaxation length parameter identification and dimensionless processing specifically include: The lateral relaxation lengths under different loads are dimensionless, and the relaxation length under the standard load is set to 1, and the remaining relaxation lengths are calculated according to the ratio; The nonlinear relaxation length model parameter identification specifically includes: The tread elastic force model is equivalent to the connection of two parts ① and ②, ① is a group of parallel spring damping units, and ② is a group of series spring damping units to express the nonlinear characteristics of non-constant relaxation length.

2. A tire cornering characteristics test method under dynamic load according to claim 1, characterized in that: The dynamic load side deviation characteristic test specifically includes: Set working conditions: set the slip angle to 1 degree and 6 degrees, and conduct two tests; set the road speed to 5 km / h; set the vertical load loading mode to sine; set the loading frequency to 0.1 Hz, 0.5 Hz, 1 Hz, 2 Hz, 4 Hz, 6 Hz, 8 Hz and 16 Hz in sequence; The relationship curves of lateral force, self-aligning moment and vertical force are output respectively.

3. A tire cornering characteristics test method under dynamic load according to claim 2, characterized in that: It also includes test curve drawing and test effect comparison: in addition to the conventional side slip force changing with side slip angle curve, it is also necessary to increase the frequency of independent variable factors and draw curves to express the dynamic load curves of the tire in the linear and nonlinear regions respectively.

4. A tire cornering characteristics test method under dynamic load according to claim 3, characterized in that: Before the dynamic step condition test and identification, do the pre-test preparation work; install the tire rim assembly on the tire six-component force test bench, adjust the tire pressure and start the six-component force test bench.

5. A tire cornering characteristics test method under dynamic load according to claim 4, characterized in that: The preparatory work before the test specifically includes: conducting a test run on the tire to eliminate stress before the formal test; setting up a test run program, that is, the tire runs from a low speed of 20km / h to a high speed of 120km / h for 10 minutes under rated load, followed by 1 minute of reciprocating motion at a small side slip angle of -1° to 1° to ensure uniform heat generation in the tire and eliminate internal stress in the tire; subsequently cooling the tire by applying a small load of 500N and a small speed of 30km / h to cool the tire until the tread temperature meets the 30℃-35℃ requirement.

6. The method for testing tire cornering characteristics under dynamic load according to claim 1, characterized in that: The working conditions set in the linear region and nonlinear region dynamic step working condition test are as follows: the test load is 10%, 40%, 70% and 100%; the side slip angle is set to 1 degree and 6 degrees; and the road speed is set to 5 km / h.

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