JP2007210528A - Temperature distribution prediction method of tire, thermal analysis model, and temperature distribution prediction calculating program of tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of accurately predicting temperature distribution of a tire during traveling. <P>SOLUTION: In this method is performed, a stress analysis model is developed composed of a tire model, a rim model, and a road model. Stress analysis is made by respectively giving physical properties such as density and an elasticity modulus to the element of each model. The heat generation distribution of the tire is determined by calculating stress σ and the amount of strain ε acting on each part of the tire. In executing heat analysis calculation based on the heat generation distribution, a three-dimensional heat analysis model constituted by adding a numeral analysis model composed of the tire model 40 and the rim model 50 to an inside air model 60 which divides air inside the tire into finite elements, a cut sample model, or an axisymmetric heat analysis model M2 to obtain the temperature distribution on the surface of and inside the tire by executing heat analysis calculation on the heat analysis model M2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method of predicting a tire temperature distribution during traveling using a numerical analysis model of a tire by dividing a tire into a finite number of elements, a thermal analysis model used therefor, and a tire temperature distribution prediction It relates to a calculation program.

Conventionally, as a method of simulating tire performance, the tire to be evaluated is approximated by a tire finite element model divided into a finite number of elements, and material properties such as density and elastic modulus are given to each finite element, The Finite Element Method is often used for numerical analysis of tire dynamics such as tire deformation and rolling resistance by applying boundary conditions such as internal pressure and load to the above model and calculating the deformation state of each element. (For example, see Patent Documents 1 and 2).
On the other hand, as one method for evaluating the durability of a tire, an evaluation method has been proposed that takes into account the temperature rise due to heat generated during rolling of a rubber material that is a viscoelastic body.
FIG. 6 is a diagram showing the flowchart, and FIG. 7 is a diagram showing an outline of a finite element model (tire model) 70 of the tire used in this evaluation method. In the tire model 70, the tire is divided into a finite number of elements 70S, rubber members such as the tread portion 71 and the side portion 72 are modeled as solid elements, and a reinforcing member such as the belt 73 is modeled as a membrane element. Therefore, when evaluating the durability, first, the tire model 70 is used to perform a static stress analysis or a dynamic analysis such as a rolling analysis to determine the stress of each element of the tire model 70. After the analysis (step S51), the stress σ and the strain ε when the tire is rotated once for each element obtained in the stress analysis are obtained, and the strain ε is determined according to the loss factor of the rubber material. The heat generation energy of each element is calculated from the area of the hysteresis loop of the stress σ and the strain ε obtained by giving the phase delay δ (step S52). Determine the temperature distribution in the case of exothermic traveling by theta (step S53).
Next, a heat transfer analysis is performed in which the modeled tire travels for a predetermined time θ to dissipate heat to predict the temperature distribution of the tire (step S54), and the predicted breakage at the temperature of each element after heat dissipation. The tire safety factor is calculated from the strength and elongation at break (step S55), and the durability of the tire is evaluated (step S56). In the analysis at the time of heat generation, it is assumed that the tire only generates heat but does not dissipate heat, and in the analysis at the time of heat dissipation, the tire only calculates heat and does not generate heat.
In this way, after performing the heat generation analysis and the heat dissipation analysis separately, by matching the heat generation time and the heat dissipation time, the prediction calculation time of the temperature distribution can be greatly shortened (for example, patent document) 3).
JP 2003-118328 A JP 2005-186900 A JP 2005-138621 A

By the way, in the conventional temperature distribution predicting method, as the heat transfer surface of the tire model 70, the contact surface with the road surface of the tread 71, the surface where the tread 71 is exposed to the outside air, and the side portion 72 are exposed to the outside air. In addition to the surface of the tire model 70, a fitting surface with a rim (not shown) of the tire model 70 is considered as a heat transfer surface. It is set.
However, in the above conventional method, not only the tire-only model is used for the heat conduction analysis, but the rim and the air inside are simply increased in the heat transfer surface of the tire. This does not take into account the flow of heat released to the outside air through the rim or the heat flow of the internal air heated by the tire to the outside air through the rim. It was difficult to obtain the distribution accurately.

  The present invention has been made in view of the conventional problems, and an object of the present invention is to provide a method capable of accurately predicting the temperature distribution of a tire during traveling.

The invention according to claim 1 of the present application creates a stress analysis model composed of a three-dimensional tire model or a three-dimensional tire model and a road surface model, and gives an elastic modulus to each rubber member element of the tire model, After calculating the stress and strain amount of each part of the tire by performing load or rolling analysis, the heat distribution of the tire obtained using the calculated stress and strain amount of each part of the tire and the loss tangent of the rubber member is obtained. In the tire temperature distribution prediction method for creating a thermal analysis model based on the thermal analysis model and performing thermal analysis calculation using the thermal analysis model to predict the temperature distribution on the tire surface and inside, the tire model is used as the thermal analysis model. Either a model in which the air inside the tire is divided into a finite number of elements, or a model in which at least part or all of the wheel including the rim is divided into a finite number of elements Create a thermal analysis model obtained by adding the rectangular or both, it is characterized in that to perform the thermal analysis calculated using the thermal analysis model.
The invention according to claim 2 is the tire temperature distribution prediction method according to claim 1, wherein the thermal analysis calculation is performed using a cut sample model or an axisymmetric two-dimensional analysis model. .
The invention according to claim 3 is a thermal analysis model used for thermal analysis calculation of the tire temperature distribution prediction method according to claim 1 or claim 2, wherein the tire model is provided with air inside the tire. One or both of a model divided into a finite number of elements and a model obtained by dividing at least a part of the wheel including at least the rim portion into a finite number of elements are added.

The invention according to claim 4 is a calculation program for predicting and calculating the temperature distribution inside and outside the tire using an analysis model in which the tire is divided into a finite number of elements.
A first step of creating a stress analysis model comprising a three-dimensional tire model or a three-dimensional tire model and a road surface model;
A second step of providing an elastic modulus to each rubber member element of the tire model;
A third step of calculating a stress and a strain amount of each part of the tire by performing load or rolling analysis using the stress analysis model;
A fourth step of obtaining a strain energy density distribution from the calculated stress and strain amount of each part of the tire and multiplying the density distribution by a loss tangent to obtain a heat generation distribution of the tire;
A three-dimensional thermal analysis model that adds a tire model to a model in which the air inside the tire is divided into a finite number of elements and a model in which at least a part or all of the wheel including the rim is divided into a finite number of elements. The temperature distribution of the tire surface and the interior is obtained by creating a thermal analysis calculation based on the heat generation distribution for the three-dimensional thermal analysis model, or the cut sample model or the axisymmetric two-dimensional analysis model. And a fifth step.
Note that the tire model according to claim 3 and claim 4 may be a tire model used in the stress analysis model according to claim 1, or a division method newly created for thermal analysis, It may be a new tire model with a different number of elements.

  According to the present invention, load or rolling analysis is performed using a stress analysis model composed of a three-dimensional tire model or a three-dimensional tire model and a road surface model to calculate the stress and strain amount of each part of the tire. Based on the heat generation distribution of the tire obtained using the stress and strain amount of each tire part and the loss tangent of the rubber member, the thermal analysis calculation is performed to predict the tire surface and the internal temperature distribution. As a numerical analysis model for performing the thermal analysis calculation, a tire model, a model in which the air inside the tire is divided into a finite number of elements, and at least a part or all of the wheel including the rim portion are converted into a finite number of elements. Create a 3D thermal analysis model with either or both of the divided models, or a cut sample model or an axisymmetric 2D analysis model By performing the thermal analysis calculation using the analysis model or the two-dimensional analysis model, the thermal analysis including heat dissipation from the rim and heat dissipation from the internal air heated by the tire to the rim is performed. Therefore, the tire temperature distribution can be obtained with high accuracy.

Hereinafter, the best mode of the present invention will be described with reference to the drawings.
1 (a) and 1 (b) are diagrams showing an outline of a stress analysis model M1 for performing tire load or rolling analysis, and FIG. 2 is a thermal analysis for performing temperature distribution prediction of the tire according to the present invention. It is a figure which shows the outline | summary of the model M2.
The stress analysis model M1 includes a tire model 10, a rim model 20, and a road surface model 30. For the tire model 10, the rubber member such as the tread portion 11 and the side portion 12 and the bead wire 13 are modeled as solid elements. The reinforcing members such as the belt 14 and the carcass ply 15 are modeled by shell elements, membrane elements, and river elements, and the rim model 20 is modeled by solid elements. On the other hand, the road surface 30 is modeled by a flat rigid shell element, but actual road surface unevenness can also be modeled (note that the rim model 20 is omitted in FIG. 1A).
On the other hand, the thermal analysis model M2 is a numerical analysis model composed of the tire model 40 and the rim model 50 divided in the same manner as the tire model 10 and the rim model 20, and further the gas (here, air) inside the tire is finite. A cut sample model of a three-dimensional thermal analysis model formed by adding an internal air model 60 divided into individual elements or an axisymmetric two-dimensional analysis model. In this example, thermal analysis calculation is performed for the thermal analysis model M2. Thus, the temperature distribution inside and inside the tire is obtained.

Next, the tire temperature distribution prediction method according to the present invention will be described with reference to the flowchart of FIG.
First, a stress analysis model as shown in FIG. 1 is created (step S11), and material properties such as elastic modulus at an initial set temperature are given as initial characteristics to each element of the models 10 to 30 (step S12). ).
Then, load or rolling analysis is performed using the stress analysis model, and stress σ and strain amount ε acting on each part of the tire are calculated (step S13).
Here, as a method of rolling the tire, set a boundary condition so that the tire and wheel rotate freely around the axle, create a model such as using joint elements, and either the road surface or the axle Can be analyzed by moving the other side in the longitudinal direction of the tire. Furthermore, it is possible to give the tire a slip angle or a camber angle, or to move the road surface so that the tire has a slip angle or a camber angle. Instead of the above rolling analysis, a flat push calculation (load analysis) of the tire model 10 may be performed.
After the calculation of the stress σ and the strain amount ε of each part of the tire is completed, the strain energy for one rotation of the tire of each element is calculated, and this is multiplied by the tan δ at the initial setting temperature of each element. The strain energy loss is calculated to determine the heat distribution of the tire (step S14).

Next, thermal analysis calculation is performed based on the obtained heat generation distribution, and the temperature distribution inside and inside the tire is obtained (step S15). In this example, the thermal analysis calculation is performed on the three-dimensional thermal analysis model or the cut sample type or axially symmetric two-dimensional analysis model (thermal analysis model) M2 shown in FIG. The internal temperature distribution is obtained. At this time, the shape of the tire model 40 is set to the shape at the time of internal pressure, and each element of the rim model 50 has a thermal conductivity matched to the material of the wheel. Set the rate as a physical property value.
As in this example, by adopting a model in which the tire model 40 and the rim model 50 are added with the internal air model 60 as the thermal analysis model M2, as shown in FIG. In addition to the heat flow emitted from the side portion 42, the heat flow emitted from the bead portion 46 to the outside air via the flange portion 51 of the rim model 50, and the base portion 52 of the rim model 50 from the inner surface of the tire model 40. Since it is possible to consider the flow of heat that is conducted to and released to the outside air, the tire temperature distribution can be obtained with high accuracy.
The thermal analysis calculation of the tread portion 41 is performed using an average heat flow in a state in contact with the road surface and a state in which the road surface is not in contact.

  As described above, in the present best mode, a stress analysis model including the tire model 10, the rim model 20, and the road surface model 30 is created, and material physical properties such as density and elastic modulus are provided in each element of each of the models 10-30. Is applied to the tire to calculate the stress σ and the strain amount ε acting on each part of the tire to obtain the heat generation distribution of the tire, and when performing the thermal analysis calculation based on the heat generation distribution, the tire model 40 A three-dimensional thermal analysis model obtained by adding an internal air model 60 obtained by dividing a gas inside a tire into a finite number of elements, or a cut sample model or an axial symmetry A two-dimensional analysis model (thermal analysis model) M2 is created, and thermal analysis calculation is performed on the thermal analysis model M2 to determine the temperature of the tire surface and the inside. Since the temperature distribution is calculated, it is possible to perform thermal analysis including heat dissipation from the rim and heat dissipation from the internal air heated by the tire to the rim. Can do.

In the above-mentioned best mode, a model in which the same elements are arranged in the tire rotation direction is adopted as the tire model 10; however, the tire model 10 is modeled in consideration of the tread pattern, or a small member as in a real tire. By modeling overlap, thickness change, and rigidity change to create a non-uniform model in the rotational direction, the accuracy of analysis can be further improved.
In addition, since the heat generation of the tire is mainly in the tread portion, the stress analysis performed in step S13 may be performed only with the tire model 10.
In the above example, the thermal analysis model M2 uses the rim model 50 in which only the rim portion is modeled. However, since the materials constituting the rim portion and the disk portion of the wheel have good thermal conductivity, in the thermal analysis, If the entire wheel is modeled, the tire temperature prediction accuracy can be further improved.
In addition, the accuracy of the thermal analysis calculation is improved if a three-dimensional model is used, but not only the boundary condition becomes complicated, but also the calculation time becomes enormous. Since the tire is a rotating body, calculation can be efficiently performed by using a cut sample type or an axially symmetric two-dimensional analysis model as in this example.

なお、上記表１の数字は、試験車両を、上記シミュレーションと同様の条件で走行させて平行状態となった時点でのベルト端の実測温度を１００としたときの予測温度である。
実施例１はタイヤモデルにリムモデルのみを付加したもの、実施例２は内部空気モデルのみを付加したもので、実施例３は、図５（ａ）に示すような、タイヤとリムと内部空気とをモデル化した熱解析モデルを用いて熱解析を行ったものである。
表１から明らかなように、本発明の実施例１〜３は、従来例の予測温度より低く、かつ、実測温度にかなり近いことから、本発明の方法を用いることにより、リムからの放熱及び内部空気からリムを介しての放熱を正確に把握することができ、タイヤ温度の予測精度を大幅に向上させることができることが確認された。
また、実施例１，２より、リムからの放熱と内部空気からの放熱とはほぼ同等であり、実施例３のように、リムと内部空気とをモデル化してタイヤモデルに付加することにより、タイヤ温度の予測精度を更に向上させることができることが確認された。 When creating a numerical analysis model of a tire with a tire size of PSR195 / 65R14, performing stress analysis for rolling on the road surface at room temperature 38 ° C, speed 80 km / h, load 100%, and performing thermal analysis calculation Conventionally, thermal analysis calculation was performed using a thermal analysis model to which one or both of the rim and internal air models were added, and the simulation was performed to predict the temperature distribution of the tire. The results compared with the examples are shown in Table 1 below.

The numbers in Table 1 above are predicted temperatures when the measured temperature of the belt end at the time when the test vehicle is driven under the same conditions as in the simulation and becomes parallel is 100.
Example 1 is obtained by adding only the rim model to the tire model, Example 2 is obtained by adding only the internal air model, and Example 3 shows the tire, the rim, the internal air, and the like as shown in FIG. The thermal analysis was performed using the thermal analysis model that modeled.
As is clear from Table 1, Examples 1 to 3 of the present invention are lower than the predicted temperature of the conventional example and quite close to the actually measured temperature. Therefore, by using the method of the present invention, heat radiation from the rim and It was confirmed that the heat radiation from the internal air through the rim can be accurately grasped and the prediction accuracy of the tire temperature can be greatly improved.
Further, from Examples 1 and 2, the heat release from the rim and the heat release from the internal air are substantially equivalent, and as in Example 3, by modeling the rim and the internal air and adding them to the tire model, It was confirmed that the prediction accuracy of the tire temperature can be further improved.

従来例は熱解析をタイヤモデルのみで行ったもので、実施例４はタイヤモデルにリムモデルのみを付加したもの、実施例５は内部空気モデルのみを付加したもので、実施例６は、図５（ｂ）に示すような、タイヤとリムと内部空気とをモデル化した熱解析モデルを用いて熱解析を行ったものである。
表２から明らかなように、本発明の実施例４〜６は、従来例の予測温度より低く、かつ、実測温度にかなり近いことから、本発明の方法を用いることにより、Ｔタイプのタイヤにおいても、温度の予測精度を大幅に向上させることができることが確認された。
また、実施例４，５より、空気圧が高く、内部空気量が相対的多いＴタイプのタイヤでは、内部空気からの放熱の方がリムからの放熱よりも若干影響が大きいこともわかった。また、実施例６のように、リムと内部空気とをモデル化してタイヤモデルに付加することにより、Ｔタイプのタイヤにおいても、タイヤ温度の予測精度を更に向上させることができることが確認された。
なお、構造の違いはそれほど大きくはなかった。 A numerical analysis model of a tire having a tire size of TBR295 / 75R22.5 was created, and the results of a simulation for predicting the tire temperature distribution in the same manner as in Examples 1 to 3 are shown in Table 2 below. In addition, as the above-mentioned tire, a tire having a ply end higher than the wire chafer end (TBR-1) and a tire having a wire chafer end higher than the ply end (TBR-2) are prepared. TBR-1 was analyzed under conditions of room temperature 38 ° C., speed 70 km / h, and load 120%, and TBR-2 was analyzed under conditions of room temperature 38 ° C., speed 70 km / h, load 110%.
The predicted and measured locations of the T-type tire are 3 belt ends, ply ends, nylon chafer ends (when the ply end is higher than the wire chafer end) or wire chafer ends (wire In the case of a tire having a structure where the chafer end is higher than the ply end; there are three locations from * mark to TBR-2) in Table 2.

In the conventional example, thermal analysis was performed only on the tire model, Example 4 was obtained by adding only the rim model to the tire model, Example 5 was obtained by adding only the internal air model, and Example 6 is shown in FIG. The thermal analysis is performed using a thermal analysis model that models the tire, the rim, and the internal air as shown in FIG.
As is apparent from Table 2, Examples 4 to 6 of the present invention are lower than the predicted temperature of the conventional example and quite close to the actually measured temperature. Therefore, by using the method of the present invention, in the T type tire, It was also confirmed that the temperature prediction accuracy can be greatly improved.
Further, from Examples 4 and 5, it was also found that in the T type tire having a high air pressure and a relatively large amount of internal air, the heat radiation from the internal air has a slightly larger effect than the heat radiation from the rim. Moreover, it was confirmed that the prediction accuracy of the tire temperature can be further improved even in the T type tire by modeling the rim and the internal air as in Example 6 and adding the model to the tire model.
The difference in structure was not so great.

  As described above, according to the present invention, the temperature distribution inside and inside the tire can be accurately simulated, so that the durability of the tire can be accurately evaluated, and the design and development efficiency of the tire can be improved. Can be made.

It is a figure which shows the stress analysis model used for the load or rolling analysis of this invention. It is a figure which shows the thermal analysis model used for the thermal analysis of this invention. It is a flowchart which shows the temperature prediction method of the tire which concerns on the best form of this invention. It is a figure for demonstrating the thermal radiation state of the tire in a thermal analysis model. It is a figure which shows an example of the thermal analysis model used for the Example of this invention. It is a figure which shows the tire model used for the temperature distribution prediction of the conventional tire. It is a flowchart which shows the temperature distribution prediction method of the conventional tire.

Explanation of symbols

M1 stress analysis model, 10 tire model, 11 tread part, 12 side part,
13 bead wires, 14 belts, 15 carcass plies, 20 rim models,
30 road surface model,
M2 thermal analysis model, 40 tire model, 41 tread part, 42 side part,
46 bead part, 50 rim model, 51 flange part, 52 base part,
60 Internal air model.

Claims (4)

  A stress analysis model composed of a three-dimensional tire model or a three-dimensional tire model and a road surface model is created, and an elastic modulus is given to each rubber member element of the tire model, and a load or rolling analysis is performed to analyze each part of the tire. After calculating the stress and strain, a thermal analysis model is created based on the tire heat distribution obtained using the calculated stress and strain of each part of the tire and the loss tangent of the rubber member. In the tire temperature distribution prediction method for predicting the temperature distribution on the surface and inside of the tire by performing thermal analysis calculation using the analysis model, the tire model is used as the above-mentioned thermal analysis model, and the air inside the tire is a finite number of elements. Analysis with one or both of the model divided into a finite part and the model where at least part or all of the wheel including the rim part is divided into a finite number of elements Create a Dell, temperature distribution prediction method of the tire, characterized in that to perform the thermal analysis calculated using the thermal analysis model.   The tire temperature distribution prediction method according to claim 1, wherein the thermal analysis calculation is performed using a cut sample model or an axisymmetric two-dimensional analysis model.   A thermal analysis model used for thermal analysis calculation of the tire temperature distribution prediction method according to claim 1 or claim 2, wherein the tire model is a model in which air inside the tire is divided into a finite number of elements, and A tire thermal analysis model characterized by adding either or both of a model in which at least a part or all of a wheel including a rim portion is divided into a finite number of elements. A calculation program for predicting and calculating the temperature distribution inside and outside the tire using an analytical model in which the tire is divided into a finite number of elements,
A first step of creating a stress analysis model comprising a three-dimensional tire model or a three-dimensional tire model and a road surface model;
A second step of providing an elastic modulus to each rubber member element of the tire model;
A third step of calculating a stress and a strain amount of each part of the tire by performing load or rolling analysis using the stress analysis model;
A fourth step of obtaining a strain energy density distribution from the calculated stress and strain amount of each part of the tire and multiplying the density distribution by a loss tangent to obtain a heat generation distribution of the tire;
A three-dimensional thermal analysis model that adds a tire model to a model in which the air inside the tire is divided into a finite number of elements and a model in which at least a part or all of the wheel including the rim is divided into a finite number of elements. The temperature distribution of the tire surface and the interior is obtained by creating a thermal analysis calculation based on the heat generation distribution for the three-dimensional thermal analysis model, or the cut sample model or the axisymmetric two-dimensional analysis model. A tire temperature distribution prediction calculation program comprising: a fifth step.

Images