How to predict the internal temperature of a tire

Abstract

This invention provides a method for predicting the internal temperature of a tire, which allows for the acquisition of the internal temperature of the tire while it is in motion. [Solution] This is a method for predicting the internal temperature of a tire T while it is in motion. The method includes: a first step S3 of finding a relational expression between the surface temperature Ta of the tire T obtained by measurement and the surface temperature Tb of the tire T obtained by calculation; a second step S4 of finding a relational expression between the surface temperature Tb of the tire T obtained by calculation and the internal temperature Tc of the tire T obtained by calculation; and a third step S5 of predicting the internal temperature Tz of a tire traveling at a certain speed from the surface temperature Tax of the tire T obtained by measuring the tire T while it is traveling at a certain speed, using the relational expression obtained in the first step and the relational expression obtained in the second step.

Description

Technical Field

[0001] The present invention relates to a method for predicting the internal temperature of a tire.

Background Art

[0002] When a vehicle is running, a tire generates heat due to frictional heat with the road surface, deformation during running, etc. This heat generation during running causes a temperature rise inside the tire and becomes a factor for damage or breakage inside the tire. In predicting the durability of a tire, etc. and developing a tire, it is important to grasp the internal temperature of the tire during running. So far, as a method for obtaining the internal temperature of a tire, for example, embedding a temperature sensor for measuring the internal temperature in the tire has been carried out (see Patent Document 1 below).

Prior Art Documents

Patent Documents

Patent Document l

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional technology, there are problems that the temperature sensor provided in the tire is easily damaged, and the location where the temperature sensor is mounted becomes the starting point of tire damage. [[ID=3~]]

[0005] The present invention has been devised in view of the above actual situation, and the main object is to provide a method for predicting the internal temperature of a tire capable of obtaining the internal temperature of a tire during running by prediction.

Means for Solving the Problems

[0006] The present invention relates to a method for predicting the internal temperature of a tire while it is in motion, comprising the steps of: obtaining the surface temperature Ta of the tire by measurement while it is in motion at least at a first speed and a second speed, respectively; obtaining the surface temperature Tb and the internal temperature Tc of the tire by calculation while it is in motion at least at the first speed and the second speed, respectively; a first step of finding a relational expression between the surface temperature Ta of the tire obtained by measurement and the surface temperature Tb of the tire obtained by calculation; a second step of finding a relational expression between the surface temperature Tb of the tire obtained by calculation and the internal temperature Tc of the tire obtained by calculation; and a third step of predicting the internal temperature Tz of the tire while it is in motion at a certain speed from the surface temperature Ta of the tire obtained by measuring the tire while it is in motion at a certain speed, using the relational expression obtained in the first step and the relational expression obtained in the second step. [Effects of the Invention]

[0007] The present invention's method for predicting the internal temperature of a tire makes it possible to obtain the internal temperature of a tire while it is in motion by prediction, by employing the above-described steps. [Brief explanation of the drawing]

[0008] [Figure 1] This is a flowchart of the prediction method in this embodiment. [Figure 2] This is a schematic perspective to explain the measurement acquisition process S1. [Figure 3] This is a cross-section of a tire. [Figure 4] This is a graph of an example of the first linear approximation formula obtained in the first step. [Figure 5] This is a graph of an example of the second linear approximation formula obtained in the second step. [Figure 6] This is a graph of an example of a third-order approximation formula obtained in the prediction process. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. The drawings contain exaggerations and representations that differ from the actual structural dimensional ratios in order to aid in understanding the content of the present invention. Furthermore, the same or common elements are denoted by the same reference numerals throughout each embodiment, and redundant explanations are omitted. In addition, the specific configurations shown in the embodiments and drawings are for the purpose of understanding the content of the present invention. It should be noted that the present invention is not limited to the specific configurations shown in the drawings.

[0010] The method for predicting the internal temperature of a tire according to the present invention (hereinafter sometimes simply referred to as the "prediction method") can predict the internal temperature of various tires, such as pneumatic tires for passenger cars and motorcycles, and non-pneumatic tires that are not filled with air. In this specification, the explanation will be given using pneumatic tires as an example.

[0011] Figure 1 is a flowchart of the prediction method of this embodiment. As shown in Figure 1, the prediction method includes a measurement acquisition step S1, a calculation acquisition step S2, a first step S3, a second step S4, and a prediction step S5.

[0012] In the prediction method of this embodiment, first, a measurement acquisition step S1 is performed. Figure 2 is a schematic perspective view illustrating the measurement acquisition step S1. As shown in Figure 2, in the measurement acquisition step S1, the surface temperature Ta of the tire T while it is running is acquired by measurement. In the measurement acquisition step S1 of this embodiment, a bench test apparatus (hereinafter sometimes referred to as "apparatus") 1 and a thermometer 10 are used. In the measurement acquisition step S1 of this embodiment, the surface temperature Ta of the tire T that has been run on the apparatus 1 is measured by the thermometer 10.

[0013] In this embodiment, the device 1 comprises a drum 2 for driving (rotating) the tire T and a tire holder 4 for rotatably holding the tire T.

[0014] In this embodiment, the drum 2 includes a cylindrical drum body 2A having a running surface 3 on which the tire T can run continuously, and a drum rotation shaft 2B that rotates the drum body 2A. In this embodiment, the running surface 3 is provided on the outer circumferential surface of the drum body 2A. The running surface 3 is formed of a material (not shown) that conforms to the particle size curve of the ISO road surface standard (see the tolerance range of the particle size curve for asphalt mixtures described in Annex C of ISO 10844, design guidelines). The drum rotation shaft 2B is rotationally driven by a drive unit 5 including an electric motor equipped with an inverter or the like that can freely adjust the rotation speed.

[0015] The tire holder 4 includes a support shaft 4A that rotatably holds the tire T, and a moving device (not shown) that moves the support shaft 4A up and down or laterally. The moving device can, for example, press the tire T held on the support shaft 4A onto the running surface 3 with a predetermined pressing force and make it run. The support shaft 4A may also have a function that can drive the tire T to rotate. This makes the tire T rotatable relative to the drum body 2A.

[0016] Figure 3 is a meridian cross-sectional view of the right half of tire T. Figure 3 shows tire T in its normal state. The "normal state" refers to an unloaded state in which the tire is mounted on a normal rim (hereinafter sometimes simply referred to as "rim") R and adjusted to the normal internal pressure. The "normal rim" refers to the rim specified for each tire in the standard system, including the standard on which the tire is based. For example, it is the "standard rim" for JATMA, the "Design Rim" for TRA, and the "Measuring Rim" for ETRTO. The "normal internal pressure" refers to the air pressure specified for each tire in the standard system, including the standard on which the tire is based. For example, it is the "maximum air pressure" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and the "INFLATION PRESSURE" for ETRTO.

[0017] The tire T includes a tread portion ta, a pair of sidewall portions tb disposed on both sides of the tread portion ta (both outer sides in the tire axial direction), and a pair of bead portions tc located on the inner side in the tire radial direction of each sidewall portion tb. Further, the tire T includes a bead core te embedded in each bead portion tc, a carcass tf extending between the bead cores te, a band layer tg located on the outer side in the tire radial direction of the carcass tf, and a tread rubber th adjacent to the outer side in the tire radial direction of the band layer tg.

[0018] The carcass tf includes, for example, a main body portion ti extending between the bead cores te and a folded-back portion tj connected to the main body portion ti and folded back from the inner side to the outer side in the tire axial direction around the bead core te. The band layer tg is provided, for example, in the tread portion ta and is sandwiched between the carcass tf and the tread rubber th. The tread rubber th includes, for example, a ground contact surface tk that contacts the running surface 3 during running. The carcass tf, the band layer tg, and the tread rubber th are configured, for example, in a well-known structure. Note that the tire T is not limited to such a mode.

[0019] Further, during running, the internal temperature of the tire T becomes relatively high, for example, in the vicinity of the outer end to in the tire axial direction of the band layer tg or in the vicinity of the inner end tn in the tire radial direction of the portion where the main body portion ti and the folded-back portion tj overlap at the bead portion tc. Therefore, it is desirable to predict the internal temperature in the vicinity of the outer end to or / and in the vicinity of the inner end tn. Note that the prediction of the internal temperature is not limited to such locations, and it may be predicted, for example, in the vicinity of the outer side in the tire radial direction of the band layer tg near the tire equator C, or may be predicted at other portions.

[0020] In the measurement acquisition step S1, it is desirable that the tire T runs, for example, under a normal load condition. The "normal load condition" is a state in which a normal load is applied to the tire in the normal state and the tire is grounded on a plane at a camber angle of 0 degrees. The "normal load" is the load determined for each tire in a standard system including the standards on which the tire is based. In the case of JATMA, it is the "maximum load capacity"; in the case of TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; and in the case of ETRTO, it is the "LOAD CAPACITY".

[0021] In this embodiment, a non-contact thermometer is used as the thermometer 10. As the non-contact thermometer, a radiation thermometer, or a thermal image sensor (thermography) capable of measuring the temperature distribution over a relatively wide area is preferable. Note that the thermometer 10 may be a contact thermometer made of, for example, a thermocouple, a resistance thermometer, or a bimetal.

[0022] In the measurement acquisition step S1, the surface temperature Ta1 of the tire T running at the first speed v1 and the surface temperature Ta2 of the tire T running at the second speed v2 are measured by the thermometer 10. The second speed v2 is, for example, a speed higher than the first speed v1. Also, in the measurement acquisition step S1, the surface temperature Tan of the tire T running at the nth speed vn may be measured by the thermometer 10. In this specification, n is a natural number of 3 or more, and is set to be a speed higher than the second speed v2, and the larger the number, the higher the speed. In the measurement acquisition step S1 of this embodiment, the surface temperatures Ta1 to Ta3 at the first speed v1, the second speed v2, and the third speed v3 are measured. In this embodiment, the first speed v1 is 60 km / h, the second speed v2 is 80 km / h, and the third speed v3 is 100 km / h (shown in FIG. 4).

[0023] The first speed v1 is the lowest speed at which the surface temperature Ta is measured. The first speed v1 is not particularly limited.

[0024] The difference (v2-v1) between the second speed v2 and the first speed v1 is preferably 10 km / h or more. Furthermore, the difference (vn-v(n-1)) between the nth speed vn and the (n-1)th speed v(n-1) is preferably the same as the difference (v2-v1). In this embodiment, the difference (v2-v1) is set to 20 km / h.

[0025] It is desirable that the surface temperature Ta measured in the measurement acquisition step S1 of this embodiment is measured at the same location as the surface temperature Tb, which will be calculated later in the calculation acquisition step S2.

[0026] Next, the calculation and acquisition process S2 is performed. In the calculation and acquisition process S2 of this embodiment, the surface temperature Tb and the internal temperature Tc of the tire T during driving are obtained by calculation. In the calculation and acquisition process S2 of this embodiment, the surface temperature Tb and the internal temperature Tc are appropriately calculated using a computer according to the procedure described in, for example, the Patent Document (Japanese Patent Application Publication No. 2020-131758). In the calculation and acquisition process S2, for example, the finite element method, the finite volume method, the difference method, or the boundary element method may be appropriately employed.

[0027] The surface temperature Tb calculated in calculation acquisition step S2 is the temperature at the location closest to the internal temperature Tc calculated in calculation acquisition step S2. The internal temperature Tc calculated in calculation acquisition step S2 is, for example, at least one of the following locations: near the outer edge to, near the inner edge tn, and near the outer edge tp. The internal temperature Tc calculated in calculation acquisition step S2 may be at a location other than near the outer edge to, near the inner edge tn, and near the outer edge tp. Furthermore, if the internal temperature Tc near the inner edge tn is calculated in calculation acquisition step S2, the surface temperature Tb calculated in calculation acquisition step S2 should be at location a on the outer surface of the tire T closest to near the inner edge tn, excluding the rim R.

[0028] In calculation acquisition step S2, the surface temperature Tb1 and internal temperature Tc1 of tire T while it is traveling at a first speed v1 are calculated, and the surface temperature Tb2 and internal temperature Tc2 of tire T while it is traveling at a second speed v2 are also calculated. In addition, in calculation acquisition step S2, the surface temperature Tbn and internal temperature Tcn of tire T while it is traveling at the nth speed vn (where n is a natural number of 3 or more) may also be acquired by calculation. It is desirable that the speed of tire T at the surface temperature Tb and internal temperature Tc calculated in calculation acquisition step S2 is the same as the speed of tire T at the surface temperature Ta measured in measurement acquisition step S1. In this embodiment, the speeds of tire T at the surface temperature Tb and internal temperature Tc calculated in calculation acquisition step S2 are 60 km / h, 80 km / h, and 100 km / h (shown in Figures 4 and 5).

[0029] Next, the first step S3 is performed. In the first step S3 of this embodiment, a relational expression is obtained between the surface temperature Ta of tire T obtained by measurement and the surface temperature Tb of tire T obtained by calculation. In the first step S3, for example, a first linear approximation formula (1) is obtained. The first linear approximation formula (1) is derived from the surface temperature Ta of tire T obtained by measurement, with the surface temperature Tb of tire T obtained by calculation being derived from the surface temperature Ta of tire T. Note that the linear approximation formula is also called a linear approximation formula.

[0030] Figure 4 shows a graph of an example of the first linear approximation equation (1) obtained in the first step S3. Thus, the first linear approximation equation (1) is expressed as Tb = e × Ta + f (where the coefficient e and intercept f are constants obtained by regression analysis). The first linear approximation equation (1) is a linear regression equation obtained by regression analysis using, for example, the least squares method, with surface temperature Ta as the explanatory variable and surface temperature Tb as the dependent variable. In the first linear approximation equation (1) shown in Figure 4, the coefficient e is 1.0574 and the intercept f is 0.6906. The first linear approximation equation (1) is derived, for example, at each point where the surface temperature Tb of tire T is calculated. In the first step S3, for example, the first linear approximation equation (1) is derived by the computer used in the calculation acquisition step S2.

[0031] Next, the second step S4 is performed. In the second step S4 of this embodiment, a relational expression is obtained between the calculated surface temperature Tb of the tire T and the calculated internal temperature Tc of the tire T. In the second step S4, for example, a second first-order approximation equation (2) is obtained. The second first-order approximation equation (2) is derived from the calculated internal temperature Tc of the tire T to the calculated surface temperature Tb of the tire T.

[0032] Figure 5 shows a graph of an example of the second linear approximation equation (2) obtained in the second step S4. As shown, the second linear approximation equation (2) is expressed as Tc = g × Tb + h (where the coefficient g and intercept h are constants obtained by regression analysis). The second linear approximation equation (2) is a linear regression equation obtained by regression analysis using, for example, the least squares method, with surface temperature Tb as the explanatory variable and internal temperature Tc as the dependent variable. In the second linear approximation equation (2) shown in Figure 5, the coefficient g is 1.7479 and the intercept h is -18.061. The second linear approximation equation (2) is derived, for example, at each point where the surface temperature Tb of the tire T is calculated, similar to the first linear approximation equation (1). In the second step S4 of this embodiment, for example, the second linear approximation equation (2) is derived by the computer used in the calculation acquisition step S2. The second step S4 may be performed between the calculation acquisition step S2 and the first step S3, or it may be performed simultaneously with the first step S3.

[0033] Next, prediction step S5 is performed. In prediction step S5 of this embodiment, the internal temperature Tz of the tire T while it is running at a certain speed is predicted from the surface temperature Tax of the tire T obtained by measuring the tire T while it is running at a certain speed. Prediction step S5 uses, for example, the relational expression obtained in the first step S3 and the relational expression obtained in the second step S4. In this embodiment, prediction step S5 uses the relational expression obtained in the first step S3 and the relational expression obtained in the second step S4 to determine a relational expression between the surface temperature Ta of the tire T obtained by measurement and the internal temperature Tc of the tire T obtained by calculation. In this embodiment, this relational expression is a third first-order approximation expression (3) obtained from the first first-order approximation expression (1) and the second first-order approximation expression (2).

[0034] Figure 6 shows a graph of an example of the third first-order approximation equation (3) obtained in the prediction step S5. In the prediction step S5 of this embodiment, the third first-order approximation equation (3) is obtained by using the first first-order approximation equation (1) and the second first-order approximation equation (2), and further graphing the measured surface temperature Tax and the internal temperature obtained from the first first-order approximation equation (1) and the second first-order approximation equation (2). The third first-order approximation equation (3) is expressed as Tz = i × Tax + j (where the coefficient i and intercept j are constants obtained by regression analysis). In the third first-order approximation equation (3) shown in Figure 6, the coefficient i is 1.8578 and the intercept j is -17.412. The third first-order approximation equation (3) is derived, for example, at each point where the surface temperature Tb of the tire T is calculated, similar to the first first-order approximation equation (1) and the second first-order approximation equation (2). Furthermore, in the prediction step S5 of this embodiment, for example, the third first-order approximation formula (3) is derived by the computer used in the calculation acquisition step S2.

[0035] As shown in Figure 6, the third approximation formula (3) can be used to predict the internal temperature Tz from the measured surface temperature Ta at a certain velocity. For example, if the measured surface temperature Tax at a certain position at a certain velocity is 60°C, the internal temperature Tz closest to that position can be predicted to be approximately 94°C.

[0036] Although particularly preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the illustrated embodiments and can be implemented in various modified forms.

[0037] [Note] The present invention includes the following embodiments.

[0038] [Invention 1] A method for predicting the internal temperature of a tire while it is in motion, A step of obtaining the surface temperature Ta of the tire while driving at least at a first speed and a second speed, A step of calculating and obtaining the surface temperature Tb and the internal temperature Tc of the tire while driving at least at the first speed and the second speed, respectively, The first step is to determine a relational expression between the tire surface temperature Ta obtained by measurement and the tire surface temperature Tb obtained by calculation, A second step involves determining a relational expression between the tire surface temperature Tb obtained by calculation and the tire internal temperature Tc obtained by calculation, The process includes a step of using the relational expression obtained in the first step and the relational expression obtained in the second step to predict the internal temperature Tz of the tire while it is traveling at a certain speed, from the surface temperature Ta of the tire obtained by measuring the tire while it is traveling at a certain speed. A method for predicting the internal temperature of a tire. [Invention 2] The relationship obtained in the first step is a first-order approximation equation, according to the method for predicting the internal temperature of a tire according to the present invention 1. [Invention 3] The relationship obtained in the second step is a second linear approximation, according to the method for predicting the internal temperature of a tire as described in the present invention, Part 2. [4th Invention] The method for predicting the internal temperature of a tire according to the present invention, wherein the prediction step involves predicting the internal temperature Tz of the tire using a third first-order approximation formula obtained from the first first-order approximation formula and the second first-order approximation formula. [5th ​​Invention] A method for predicting the internal temperature of a tire according to any one of the present invention 1 to 4, wherein in the step obtained by the above calculation, the surface temperature Tb of the tire and the internal temperature Tc of the tire are obtained by calculation using the finite element method. [Invention 6] A method for predicting the internal temperature of a tire according to any one of invention 1 to 5, wherein the step obtained by the above measurement is to measure the surface temperature Ta of the tire at the same location as the surface temperature Tb of the tire. [7th Invention] A method for predicting the internal temperature of a tire according to any one of invention 1 to 6, wherein the step obtained by the above measurement involves measuring the surface temperature Ta of the tire with a contact thermometer or a non-contact thermometer. [Explanation of Symbols]

[0039] S3 1st process S4 2nd process S5 Prediction process T-tire Ta surface temperature Tax surface temperature Tb surface temperature Tc internal temperature Tz internal temperature

Claims

1. A method for predicting the internal temperature of a tire while it is in motion, A step of obtaining the surface temperature Ta of the tire while driving at least at a first speed and a second speed by measurement, A step of calculating and obtaining the surface temperature Tb and internal temperature Tc of the tire while driving at least at the first speed and the second speed, respectively, The first step is to determine a relational expression between the tire surface temperature Ta obtained by measurement and the tire surface temperature Tb obtained by calculation, A second step involves determining a relational expression between the tire surface temperature Tb obtained by calculation and the tire internal temperature Tc obtained by calculation, The process includes a step of using the relational expression obtained in the first step and the relational expression obtained in the second step to predict the internal temperature Tz of the tire while it is traveling at a certain speed, from the surface temperature Ta of the tire obtained by measuring the tire while it is traveling at a certain speed. A method for predicting the internal temperature of a tire.

2. The method for predicting the internal temperature of a tire according to claim 1, wherein the relational expression obtained in the first step is a first-order approximation formula.

3. The method for predicting the internal temperature of a tire according to claim 2, wherein the relational expression obtained in the second step is a second first-order approximation formula.

4. The method for predicting the internal temperature of a tire according to claim 3, wherein the prediction step involves predicting the internal temperature Tz of the tire using a third first-order approximation formula obtained from the first first-order approximation formula and the second first-order approximation formula.

5. The method for predicting the internal temperature of a tire according to any one of claims 1 to 4, wherein in the step of obtaining the results by the calculation, the surface temperature Tb of the tire and the internal temperature Tc of the tire are obtained by calculation using the finite element method.

6. The method for predicting the internal temperature of a tire according to any one of claims 1 to 4, wherein the step obtained by the measurement involves measuring the surface temperature Ta of the tire at the same location as the surface temperature Tb of the tire.

7. The method for predicting the internal temperature of a tire according to any one of claims 1 to 4, wherein in the step obtained by the measurement, the surface temperature Ta of the tire is measured with a contact thermometer or a non-contact thermometer.

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