Method and device for measuring lateral slack length of tire

Abstract

The present invention discloses a method and device for measuring the lateral slack length of a tire, and the measuring method comprises the following steps: step S1, mounting a tire to be measured on a six-component force test bench, and making the tire run on the six-component force test bench with a preset load and a preset speed; step S2, when the tire runs stably, performing a sinusoidal input with a preset amplitude on the tire, and changing the frequency of the sinusoidal input for multiple times, and obtaining the yaw angle and lateral force when the tire is running; step S3, calculating the transfer function of the lateral force and the yaw angle; step S4, fitting the curve of the transfer function; step S5, calculating the lateral slack length of the tire according to the curve of the transfer function. According to the method for measuring the lateral slack length of the tire of the present invention, the lateral slack length of the tire under the influence of the tire turning can be effectively calculated, avoiding the problem of inaccurate calculation results due to the influence of the turning angle coupling in the traditional method, and improving the measurement accuracy of the lateral slack length of the tire.

Description

Technical Field

[0001] The invention relates to the technical field of vehicle manufacturing, and in particular to a method and a device for measuring the lateral relaxation length of a tire. Background Art

[0002] The lateral relaxation length of the tire is an important indicator for measuring the transient lateral mechanical response of the tire, and has a significant impact on the transient steering characteristics of the vehicle. There is no response test standard for the lateral relaxation length characteristics of the tire at home and abroad, and the evaluation of the steering response delay in the chassis adjustment of the vehicle is an important evaluation indicator. A complete and accurate test of the lateral relaxation characteristics of the tire is essential for the testing and simulation of the steering performance of the vehicle.

[0003] Currently, there are three main methods for testing the lateral relaxation length of tires in the industry: stiffness ratio method, slip angle step method, and slip angle sinusoidal sweep method.

[0004] 1. Stiffness ratio method: by testing the tire's lateral stiffness and cornering stiffness, the ratio of the two is calculated, which is the lateral relaxation length. This method assumes that the tire's lateral stiffness is the same in dynamic and static conditions, so it has major problems in terms of trend and accuracy.

[0005] Second, the side slip angle step method, by simulating the tire side slip angle from 0 to 1°, record the curve of the tire lateral force changing with the rolling distance, and take the distance rolled when the lateral force reaches 0.632 times the steady-state value as the lateral relaxation length. There are two ways to implement this test method. The first way is to rotate the tire through a side slip angle of 1° when it is stationary, and then load it on a stationary test bench. After stabilization, the speed increases from 0 to the specified speed. The defect of this method is that the speed loading rate of the tire is very unstable, resulting in inaccurate rolling distance in the test data, thereby affecting the accuracy of the calculation of the lateral relaxation length. The second way is to run the tire stably at a specified speed, and then change the side slip angle from 0 to 1° at the maximum angular velocity. The speed data obtained by this method is stable, but the data coupling before the side slip angle stabilizes cannot be eliminated in the calculation process, which will cause the calculated lateral relaxation length value to be larger than the actual result.

[0006] 3. Side slip angle sine sweep method. The main idea of ​​this test method is to calculate the lateral relaxation length by testing the time phase difference between the tire lateral force and the side slip angle under the condition of the tire side slip angle sinusoidal input during uniform speed operation. In this test method, the sine change of the tire side slip angle will produce a lateral force input with a cosine change of the slip angle, resulting in inaccurate calculation results. The first two categories are widely used due to the convenience of test data processing, while the side slip angle sine sweep method is less used due to the difficulty of data processing. Summary of the invention

[0007] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention is to provide a method for measuring the lateral slack length of a tire, which can effectively calculate the lateral slack length of the tire under the influence of tire turning, thereby improving the measurement accuracy of the lateral slack length of the tire.

[0008] The present invention also provides a device for measuring the lateral slack length of a tire.

[0009] According to the first aspect of the present invention, the method for measuring the lateral relaxation length of a tire comprises the following steps: step S1, mounting the tire to be measured on a six-component force test bench, and allowing the tire to run on the six-component force test bench at a preset load and a preset speed; step S2, when the tire is running stably, performing a sinusoidal input with a preset amplitude on the tire, and changing the frequency of the sinusoidal input multiple times to obtain the yaw angle and lateral force of the tire during operation; step S3, calculating the transfer function of the lateral force and the yaw angle; step S4, fitting the curve of the transfer function; step S5, calculating the lateral relaxation length of the tire according to the curve of the transfer function.

[0010] According to the method for measuring the lateral slack length of a tire of the present invention, by directly deriving the transfer function of the lateral force and the yaw angle and eliminating the influence of the turning angle, an accurate test result is obtained, and the lateral slack length of the tire under the influence of the tire turning is effectively calculated, thereby avoiding the problem of inaccurate calculation results due to the influence of the turning angle coupling in the traditional method, and improving the measurement accuracy of the lateral slack length of the tire.

[0011] In some embodiments, fitting the curve of the transfer function includes: fitting the curve of the transfer function by a predetermined formula, wherein the predetermined formula is:

[0012]

[0013] Where Cc is the lateral stiffness per unit length of the tire belt; p is the Laplace variable, σ is the distance from the starting point of the side slip to the tire contact point, and a is the half-length of the tire contact.

[0014] In some embodiments, in step S5, the lateral relaxation length σ of the tire is y Satisfy: σ y =σ+a.

[0015] In some embodiments, the preset amplitude is 1°-3°.

[0016] In some embodiments, the multiple changes in the frequency of the sinusoidal input include: gradually increasing the frequency of the sinusoidal input from 0.1 Hz to 5 Hz.

[0017] In some embodiments, in step S1, the preset load is 200kg-1000kg, and the preset speed is 5km / h-40km / h.

[0018] According to the second aspect of the present invention, a device for measuring the lateral relaxation length of a tire comprises: a six-component force test bench for mounting a tire; a loading module, the loading module being used to apply a load to the tire; a driving module, the driving module being used to drive the tire to rotate; a sinusoidal input module, the sinusoidal input module being used to perform sinusoidal input on the tire; an acquisition module, the acquisition module being used to acquire the yaw angle and lateral force of the tire; a processing module, the processing module being used to calculate the transfer function of the lateral force and the yaw angle of the tire; a fitting module, the fitting module being used to fit the curve of the transfer function; and a calculation module, the calculation module being used to calculate the lateral relaxation length of the tire.

[0019] In some embodiments, the fitting module fits the curve of the transfer function according to a predetermined formula, and the preset formula is:

[0020]

[0021] Where Cc is the lateral stiffness per unit length of the tire belt; p is the Laplace variable, σ is the distance from the starting point of the side slip to the tire contact point, and a is the half-length of the tire contact.

[0022] In some embodiments, the lateral slack length σ of the tire y Satisfy: σ y =σ+a.

[0023] In some embodiments, the preset amplitude is 1°-3°, and the sinusoidal input module is used to gradually increase the frequency of the sinusoidal input from 0.1 Hz to 5 Hz.

[0024] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a flow chart of a method for measuring lateral slack length of a tire according to an embodiment of the present invention;

[0026] Figure 2 is a graph of a transfer function of lateral force and yaw angle according to an embodiment of the present invention;

[0027] Figure 3 is a schematic diagram of the amplitude and frequency of a sinusoidal input according to an embodiment of the present invention;

[0028] Figure 4 is a schematic diagram of another set of amplitudes and frequencies of a sinusoidal input according to an embodiment of the present invention;

[0029] Figure 5 is a fitting image of a transfer function according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0031] Reference below Figure 1-Figure 5 A method for measuring the lateral slack length of a tire according to an embodiment of the present invention is described.

[0032] like Figure 1 As shown, the method for measuring the lateral relaxation length of a tire according to an embodiment of the present invention comprises the following steps:

[0033] Step S1, mounting a tire to be measured on a six-component force test bench, and allowing the tire to run on the six-component force test bench at a preset load and a preset speed;

[0034] Step S2: When the tire is running stably, a sinusoidal input is applied to the tire with a preset amplitude, and the frequency of the sinusoidal input is changed multiple times to obtain the yaw angle and lateral force of the tire during operation;

[0035] Step S3, calculating the transfer function of the lateral force and the yaw angle;

[0036] Step S4, fitting a curve of the transfer function;

[0037] Step S5: Calculate the lateral slack length of the tire according to the curve of the transfer function.

[0038] That is to say, firstly, the tire to be measured is mounted on the six-component force test bench, and the tire is run on the six-component force test bench at a preset load and preset speed. Then, when the tire runs stably, a sine input is applied to the tire with a preset amplitude, and the frequency of the sine input is changed multiple times to obtain the yaw angle and lateral force of the tire during operation. Then, the transfer function of the lateral force and yaw angle is calculated, and then the curve of the transfer function is fitted. Finally, the lateral relaxation length of the tire is calculated according to the curve of the transfer function. In this way, the problem of inaccurate calculation results due to the influence of the steering angle coupling in the traditional method is avoided.

[0039] According to the method for measuring the lateral slack length of a tire in an embodiment of the present invention, by directly deriving the transfer function of the lateral force and the yaw angle, the influence of the turning angle is eliminated, and accurate test results are obtained. The lateral slack length of the tire under the influence of the tire turning is effectively calculated, thereby avoiding the problem of inaccurate calculation results due to the coupling influence of the turning angle in traditional methods, and improving the measurement accuracy of the lateral slack length of the tire.

[0040] It should be noted here that the transfer function curve of lateral force and sideslip angle is calculated by Laplace transform, because the sideslip angle read on the six-component force test bench is actually the yaw angle of the tire, and the sideslip angle is actually the yaw angle coupled with the influence of the steering angle.

[0041] Further, fitting the curve of the transfer function includes: fitting the curve of the transfer function by a predetermined formula, the predetermined formula being:

[0042]

[0043] Where Cc is the lateral stiffness per unit length of the tire belt; p is the Laplace variable, σ is the distance from the starting point of the side slip to the tire contact point, and a is the half-length of the tire contact.

[0044] It is understood that the Laplace variable p can be replaced by the path frequency w, which is the ratio of the angular frequency of the tire's longitudinal motion when it deflects according to the sine wave to the speed of the tire,

[0045]

[0046] Where v is the rolling speed of the tire, f α is the side slip angle scanning frequency, i is a complex number, i 2 =-1.

[0047] Further, in step S5, the lateral slack length σ of the tire y Satisfy: σ y =σ+a.

[0048] Furthermore, the preset amplitude is 1°-3°.

[0049] Preferably, the preset amplitude is 2°.

[0050] Furthermore, changing the frequency of the sinusoidal input multiple times includes: gradually increasing the frequency of the sinusoidal input from 0.1 Hz to 5 Hz. Thus, as many loads and frequencies as possible are distributed to more completely reflect the response of the tire under different loads and frequencies.

[0051] Further, in step S1, the preset load is 200kg-1000kg, and the preset speed is 5km / h-40km / h. The preset load is set according to actual needs, and the preset speed is preferably 20km / h.

[0052] Reference Figure 2 As shown, where F y Tire lateral force;

[0053] C Fα Tire cornering stiffness;

[0054] ψ yaw angle;

[0055] Imaginary part of transfer function (normalized transfer function);

[0056] Real part of the transfer function (normalized transfer function);

[0057] a half length of tire contact;

[0058] λ path wavelength (λ = 1 / w );

[0059] φ Fψ The phase lag angle between the lateral force and the yaw angle.

[0060] According to the measuring device of the tire lateral relaxation length of the second embodiment of the utility model, the measuring device includes: a six-component force test bench, a loading module, a driving module, a sinusoidal input module, a collection module, a processing module, a fitting module, and a calculation module.

[0061] Specifically, the six-component force test bench is used to install the tire, the loading module is used to apply load to the tire, the driving module is used to drive the tire to rotate, the sine input module is used to perform sine input on the tire, the acquisition module is used to acquire the yaw angle and lateral force of the tire, the processing module is used to calculate the transfer function of the lateral force and yaw angle of the tire, the fitting module is used to fit the curve of the transfer function, and the calculation module is used to calculate the lateral relaxation length of the tire. Therefore, the measuring device has a simple structure and is easy to use.

[0062] According to the device for measuring the lateral slack length of a tire in an embodiment of the present invention, by directly deriving the transfer function of the lateral force and the yaw angle, the influence of the turning angle is eliminated to obtain accurate test results, and the lateral slack length of the tire under the influence of the tire turning is effectively calculated, thereby avoiding the problem of inaccurate calculation results due to the influence of the turning angle coupling in the traditional method, and improving the measurement accuracy of the lateral slack length of the tire.

[0063] Furthermore, the fitting module fits the curve of the transfer function according to a predetermined formula, and the preset formula is:

[0064]

[0065] Where Cc is the lateral stiffness per unit length of the tire belt; p is the Laplace variable, σ is the distance from the starting point of the side slip to the tire contact point, and a is the half-length of the tire contact.

[0066] It is understood that the p Plas variable can be replaced by the path frequency w, which is the ratio of the angular frequency of the tire's longitudinal motion when it deflects according to a sinusoidal wave to the speed of the tire.

[0067]

[0068] Where v is the rolling speed of the tire, f α is the side slip angle scanning frequency, i is a complex number, i 2 =-1.

[0069] Furthermore, the lateral slack length σ of the tire y Satisfy: σ y =σ+a.

[0070] Furthermore, the preset amplitude is 1°-3°, and the sine input module is used to gradually increase the frequency of the sine input from 0.1 Hz to 5 Hz. Thus, as many loads and frequencies as possible are distributed, which can more completely reflect the response of the tire under different loads and frequencies.

[0071] Preferably, the preset amplitude is 2°.

[0072] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" 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, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0073] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0074] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0075] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0076] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for measuring the lateral slack length of a tire, characterized in that: The measuring method comprises the following steps: Step S1, mounting a tire to be measured on a six-component force test bench, and allowing the tire to run on the six-component force test bench at a preset load and a preset speed; Step S2: when the tire is running stably, a sinusoidal input is applied to the tire with a preset amplitude, and the frequency of the sinusoidal input is changed multiple times to obtain the yaw angle and lateral force of the tire during operation; Step S3, calculating the transfer function of the lateral force and the yaw angle; Step S4, fitting the curve of the transfer function, wherein fitting the curve of the transfer function comprises: fitting the curve of the transfer function by a preset formula, wherein the preset formula is: Where Cc is the lateral stiffness per unit length of the tire belt; p is the Laplace variable, σ is the distance from the starting point of the side slip to the tire contact point, and a is the half-length of the tire contact; Step S5: Calculate the lateral relaxation length of the tire according to the curve of the transfer function, where the lateral relaxation length σ of the tire is y Satisfy: σ y =σ+a, where σ is the distance from the starting point of the sideslip to the point where the tire touches the ground, and a is the half-length of the tire touching the ground.

2. The method for measuring the lateral slack length of a tire according to claim 1, characterized in that: The preset amplitude is 1°-3°.

3. The method for measuring the lateral slack length of a tire according to claim 1, characterized in that: The multiple changing of the frequency of the sinusoidal input includes: gradually increasing the frequency of the sinusoidal input from 0.1 Hz to 5 Hz.

4. The method for measuring the lateral slack length of a tire according to claim 1, characterized in that: In the step S1, the preset load is 200kg-1000kg, and the preset speed is 5km / h-40km / h.

5. A device for measuring the lateral slack length of a tire, characterized in that: include: Six-component force test bench for mounting tires; A loading module, the loading module is used to apply a load to the tire; A driving module, the driving module is used to drive the tire to rotate; A sinusoidal input module, the sinusoidal input module is used to perform sinusoidal input to the tire with a preset amplitude; A collection module, the collection module is used to collect the yaw angle and lateral force of the tire; a processing module, the processing module being used to calculate a transfer function of the lateral force and the yaw angle of the tire; A fitting module, the fitting module is used to fit the curve of the transfer function, the fitting module fits the curve of the transfer function according to a preset formula, and the preset formula is: Where Cc is the lateral stiffness per unit length of the tire belt; p is the Laplace variable, σ is the distance from the starting point of the side slip to the tire contact point, and a is the half-length of the tire contact; A calculation module, the calculation module is used to calculate the lateral relaxation length of the tire, the lateral relaxation length of the tire σ y Satisfy: σ y =σ+a, σ is the distance from the starting point of the sideslip to the point where the tire touches the ground, and a is the half-length of the tire touching the ground.

6. The device for measuring the lateral slack length of a tire according to claim 5, characterized in that: The preset amplitude is 1°-3°, and the sinusoidal input module is used to gradually increase the frequency of the sinusoidal input from 0.1 Hz to 5 Hz.

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