JP2017067486A - Method for creating tire model and method for simulating tire temperature - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a temperature calculation possible in which the heat dissipation of a lateral groove is taken into account while shortening the time in creating a tire model.SOLUTION: Provided are a method for creating a tire model for numerically analyzing, using a computer, a tire provided with recesses recessed from a rubber part including tread rubber and a method for simulating a tire temperature. The creation method includes a step S1 for inputting a tire model modeled from a tire 2 having its recesses filled to the computer, and a thermal conductivity definition step S3 for defining a coefficient of thermal conductivity for each element of the tire model. The thermal conductivity definition step S3 includes a step for defining a first coefficient of thermal conductivity for the element of a non-recessed region that is a portion other than the recesses of the rubber part of the tire model, and a step for defining a second coefficient of thermal conductivity larger than the first coefficient of thermal conductivity for at least some of the elements of the recessed regions of the rubber part of the tire model.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for creating a tire model used for calculating a tire temperature, and a method for simulating a tire temperature using the tire model.

  In recent years, a simulation method for calculating the tire temperature during running has been proposed using a computer (see, for example, Patent Document 1 below). In the simulation method of Patent Document 1 below, a tire model in which a tire is modeled with a finite number of elements is used. In the tread rubber of this tire model, a tread pattern including a main groove extending continuously in the tire circumferential direction and a lateral groove extending in a direction intersecting with the main groove is reproduced.

JP 2013-0775654 A

  To create the tire model of Patent Document 1, it is necessary to subdivide the tread pattern into a finite number of elements. For this reason, it took a lot of time to create the tire model. In particular, since the shape of the lateral groove is more complicated than the shape of the main groove, it takes much time to subdivide the lateral groove.

  The present invention has been devised in view of the actual situation as described above, and a tire model creation method capable of calculating a temperature in consideration of heat dissipation of a recess such as a lateral groove while shortening the tire model creation time, The main object is to provide a tire temperature simulation method.

  The present invention is a method for creating a tire model for numerically analyzing a tire provided with a recess recessed from a rubber portion including tread rubber using a computer, and the recess is embedded in the computer. A step of inputting a tire model obtained by modeling the tire in a finite state with a finite number of elements, and a step of defining a thermal conductivity for each element of the tire model in the computer. The thermal conductivity defining step includes defining a first thermal conductivity in the non-recessed region element that is a portion other than the recessed portion of the rubber portion of the tire model, and the tire model. Defining a second thermal conductivity larger than the first thermal conductivity in at least a part of the element of the concave region that was the concave portion of the rubber portion of And wherein the door.

  In the tire model creating method according to the present invention, the tire model is preferably a two-dimensional model having a meridian cross section including a tire rotation axis.

  In the method for creating a tire model according to the present invention, the tire model is a three-dimensional model, and is continuous in a tire circumferential direction including a length in a tire axial direction of the recessed portion of the rubber portion of the tire model. It is desirable that the second thermal conductivity is defined in a region to be used.

  The tire temperature simulation method according to the present invention uses the tire model created by the method according to any one of claims 1 to 3, and the computer uses the tire condition based on the predetermined condition and the thermal conductivity. A calculation step for calculating a physical quantity related to the temperature of the tire model is included.

  The tire model creation method of the first invention of the present application includes a step of inputting a tire model obtained by modeling a tire in which a recess is filled into a computer with a finite number of elements, and each of the tire models to a computer. Each element includes a defining step that defines the thermal conductivity. Since the tire model creation method according to the first invention of the present application does not need to be divided in accordance with the shape of the recess of the tire, the tire model creation time can be shortened.

  The defining step includes a step of defining the first thermal conductivity in a non-recessed region element that is a portion other than the recessed portion of the rubber portion of the tire model, and a recessed portion that is the recessed portion of the rubber portion of the tire model. Defining at least a portion of the region elements a second thermal conductivity greater than the first thermal conductivity.

  As described above, the tire model creation method according to the first invention of the present application can adjust the temperature of the tire model in consideration of heat dissipation in the recess of the tire, for example, even if the recess is not set in the rubber portion of the tire model. Relevant physical quantities can be calculated. Therefore, the tire model created in the first invention of the present application does not have a recess, but can calculate a temperature in consideration of the heat dissipation of the recess.

  The tire temperature simulation method of the second invention of the present application uses the tire model created in the first invention of the present application, and the computer calculates the temperature of the tire model based on predetermined conditions and thermal conductivity. Including a calculation step of calculating a physical quantity related to.

  In the tire model created in the first invention of the present application, the first thermal conductivity is set in the element of the non-recessed region, and the second thermal conductivity larger than the first thermal conductivity is defined in the recessed region. Has been. Therefore, the tire temperature simulation method according to the second invention of the present application can calculate a physical quantity related to the temperature of the tire model in consideration of the heat dissipation of the recess. The tire temperature simulation method according to the second invention of the present application uses a tire model in which a recess is not provided in a rubber part. For example, when a tire model in which a recess is provided in a rubber part is used. Compared with this, the calculation time can be shortened.

It is a perspective view which shows an example of a computer. It is sectional drawing which shows an example of the tire modeled by the preparation method of the tire model of this embodiment. It is a flowchart which shows an example of the process sequence of the preparation method of a tire model. It is a perspective view which shows an example of a tire model and a road surface model. It is sectional drawing of the tire model of FIG. FIG. 6 is an enlarged view of the tread rubber of the tire model shown in FIG. 5. It is a flowchart which shows an example of the process sequence of a heat transfer rate definition process. It is a flowchart which shows an example of the process sequence of a thermal conductivity definition process. It is a flowchart which shows an example of the process sequence of the simulation method of a tire temperature. It is a flowchart which shows an example of the process sequence of a boundary condition setting process. It is a flowchart which shows an example of the process sequence of a calculation process. It is a flowchart which shows an example of the process sequence of the 2nd thermal conductivity definition process of other embodiment of this invention. It is a flowchart which shows an example of the process sequence of the 2nd thermal conductivity definition process of further another embodiment of this invention. It is a flowchart which shows an example of the process sequence of a 1st relational expression definition process. It is a flowchart which shows an example of the process sequence of a 2nd relational expression definition process. It is a fragmentary perspective view of the tread rubber of the three-dimensional tire model of other embodiments of the present invention. It is a fragmentary perspective view of the tread rubber of the three-dimensional tire model of further another embodiment of the present invention. It is a graph which shows the relationship between the temperature of the evaluation object part at the time of driving | running | working of the tire of Experimental example 2 (70km / h), and the temperature of the evaluation object part at the time of driving | running | working of the tire model of Example 7 (70km / h). It is a graph which shows the relationship between the temperature of the evaluation object part at the time of driving | running | working of the tire of Experimental example 2 (80km / h), and the temperature of the evaluation object part at the time of driving | running | working of the tire model of Example 7 (80km / h). It is a graph which shows the relationship between the temperature of the evaluation object part at the time of driving | running | working of the tire of Experimental example 2 (90km / h), and the temperature of the evaluation object part at the time of driving | running | working of the tire model of Example 7 (90km / h). It is a graph which shows the relationship between the temperature of the evaluation object part at the time of driving | running | working of the tire of Experimental example 3 (70km / h), and the temperature of the evaluation object part at the time of driving | running | working of the tire model of Example 8 (70km / h). It is a graph which shows the relationship between the temperature of the evaluation object part at the time of driving | running | working of the tire of Experimental example 3 (80km / h), and the temperature of the evaluation object part at the time of driving | running | working of the tire model of Example 8 (80km / h). It is a graph which shows the relationship between the temperature of the evaluation object part at the time of driving | running | working of the tire of Experimental example 3 (90km / h), and the temperature of the evaluation object part at the time of driving | running | working of the tire model of Example 8 (90km / h).

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The tire model creation method of the present embodiment (hereinafter sometimes simply referred to as “creation method”) is for creating a tire model for numerical analysis using a computer.

  FIG. 1 is a perspective view illustrating an example of a computer for executing a creation method of the present embodiment and a simulation method described later. The computer 1 includes a main body 1a, a keyboard 1b, a mouse 1c, and a display device 1d. The main body 1a is provided with, for example, an arithmetic processing unit (CPU), a ROM, a working memory, a storage device such as a magnetic disk, and disk drive devices 1a1 and 1a2. In addition, the storage device stores in advance the creation method of the present embodiment, software for executing a simulation method described later, and the like.

  FIG. 2 is a cross-sectional view showing an example of a tire modeled by the creation method of the present embodiment. The tire 2 of the present embodiment is configured as a heavy load tire, for example. The tire 2 according to the present embodiment is disposed, for example, on the carcass 6 extending from the tread portion 2a through the sidewall portion 2b to the bead core 5 of the bead portion 2c, and on the outer side in the tire radial direction of the carcass 6 and inside the tread portion 2a. A belt layer 7 is provided.

  Further, the tire 2 is provided with a rubber portion 11. The rubber portion 11 includes a tread rubber 11a disposed outside the belt layer 7 in the tread portion 2a, a sidewall rubber 11b disposed outside the carcass 6 in the sidewall portion 2b, and a clinch rubber disposed in the bead portion 2c. 11c. Further, the rubber portion 11 includes a bead apex rubber 11 d extending from the bead core 5 to the outer side in the tire radial direction, and an inner liner rubber 11 e forming the tire lumen surface 10 s of the tire 2. The tread rubber 11a is provided with a tread grounding surface 12 between the tread grounding ends 2t and 2t.

  The rubber portion 11 is provided with a recess 18 that is recessed from the outer surface. The recessed part 18 of this embodiment is comprised as the groove | channel 13 recessed from the tread grounding surface 12 of the tread rubber 11a. The groove 13 includes a main groove 13A extending continuously in the tire circumferential direction and a plurality of lateral grooves 13B extending in a direction crossing the main groove 13A.

  The tread ground contact end 2t is the tire rim direction of the tread ground contact surface 12 in the normal load state in which the normal rim R is assembled and filled with the normal internal pressure, the normal load is applied, and the camber angle is 0 degrees to contact the plane. It means the position of the outermost end. In addition, a rim contact surface 16 described later is also specified in a normal load state.

  The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, “Standard Rim” for JATMA, “Design Rim” for TRA, ETRTO Then "Measuring Rim".

  “Regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. “JAMATA” is the “maximum air pressure”, TRA is the table “TIRE LOAD LIMITS” The maximum value described in "AT VARIOUS COLD INFLATION PRESSURES". If ETRTO, "INFLATION PRESSURE".

  “Regular load” is the load specified by the standard for each tire. If JATMA, maximum load capacity, if TRA, maximum value described in table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES”, ETRTO If so, it is "LOAD CAPACITY".

  The main groove 13A of the present embodiment continuously extends in the tire circumferential direction between a pair of center main grooves 13Aa, 13Aa that are continuous in the tire circumferential direction, and between each center main groove 13Aa, 13Aa and the tread ground contact end 2t. A pair of shoulder main grooves 13Ab and 13Ab are provided. Accordingly, the tread rubber 11a includes a center land portion 14a divided by a pair of center main grooves 13Aa and 13Aa, a middle land portion 14b divided by the center main groove 13Aa and the shoulder main groove 13Ab, and a shoulder main groove. A shoulder land portion 14c divided by 13Ab and the tread grounding end 2t is provided.

  The lateral groove 13B of the present embodiment includes a center lateral groove 13Ba extending between the pair of center main grooves 13Aa and 13Aa, a middle lateral groove 13Bb extending between the center main groove 13Aa and the shoulder main groove 13Ab, and the shoulder main groove 13Ab and the tread grounding. A shoulder lateral groove 13Bc extending from the end 2t is included. Accordingly, the tread rubber 11a includes a center block 15a in which the center land portion 14a is partitioned by the center lateral groove 13Ba, a middle block 15b in which the middle land portion 14b is partitioned by the middle lateral groove 13Bb, and the shoulder land portion 14c in the shoulder lateral groove. A shoulder block 15c divided by 13Bc is provided. In addition, each lateral groove 13Ba, 13Bb, and 13Bc may terminate at least one of both ends in the tire axial direction within each land portion 14a, 14b, 14c. Thereby, each land part 14a, 14b, 14c is formed as a rib which continues in a tire peripheral direction.

  The clinch rubber 11c has a rim contact surface 16 that contacts the rim R. The side wall rubber 11 b and the tread rubber 11 a have a side surface 17 between the tread grounding end 2 t and the rim contact surface 16. The outer surface of the tire 2 is formed by the tread contact surface 12, the main groove 13 </ b> A, the lateral groove 13 </ b> B, the rim contact surface 16 and the side surface 17.

  The carcass 6 is composed of at least one carcass ply 6A in this embodiment. The carcass ply 6A is folded from the inner side to the outer side in the tire axial direction around the bead core 5 extending from the main body 6a, extending from the tread 2a to the bead core 5 of the bead 2c through the sidewall 2b. And a folded portion 6b. In the carcass ply 6A, for example, carcass cords arranged at an angle of 80 degrees to 90 degrees with respect to the tire equator C are overlapped so as to cross each other.

  The belt layer 7 includes, for example, four belt plies 7A to 7D in which steel belt cords are arranged at an angle of, for example, 10 ° to 70 ° with respect to the tire circumferential direction. These belt plies 7 </ b> A to 7 </ b> D are stacked with one or more places where the belt cords cross each other between the plies.

  Next, a creation method of this embodiment for creating a tire model based on the tire 2 shown in FIG. 2 will be described.

  The tire model of this embodiment is used for calculation of a physical quantity related to the temperature of the tire 2 in a simulation described later. For this reason, thermal conductivity is defined in the tire model. In the present embodiment, the tire model in which the thermal conductivity is defined is exemplified as a two-dimensional model. FIG. 3 is a flowchart illustrating an example of a processing procedure of the creation method of the present embodiment. FIG. 4 is a perspective view of the tire model and road surface model of the present embodiment. FIG. 5 is a cross-sectional view of the tire model.

  In the creation method of the present embodiment, first, a tire model obtained by modeling the tire 2 is input to the computer 1 (step S1). In step S1, a three-dimensional tire model 20a is set. The three-dimensional tire model 20a models (discretizes) the tire 2 shown in FIG. 2 with a finite number of elements F (i) (i = 1, 2,...) That can be handled by a numerical analysis method. Set by As the numerical analysis method, for example, a finite element method, a finite volume method, a difference method, or a boundary element method can be appropriately employed. In this embodiment, the finite element method is adopted.

  As shown in FIG. 5, each element F (i) is provided with a plurality of nodes 35. Each element F (i) includes an element number, a node number 35, a coordinate value of the node 35, and material characteristics (for example, density, Young's modulus, damping coefficient, and / or loss tangent tan δ) of each member. Etc.) are defined.

  As shown in FIG. 4, the three-dimensional tire model 20a of the present embodiment includes the tire 2 in a state where the recesses 18 (in the present embodiment, the lateral grooves 13B (shown in FIG. 2)) excluding the main groove 13A are filled. (For example, the contour of the tire 2 acquired from design data (for example, CAD data) of the vulcanization mold), and is modeled by the element F (i).

  In general, the shape of the lateral groove 13B of the tire 2 is more complicated than the shape of the main groove 13A. Therefore, when subdividing (discretizing) according to the shape of the lateral groove 13B, a lot of time is required. In the step S1 of the present embodiment, since it is not necessary to subdivide the lateral grooves 13B, the creation time of the three-dimensional tire model 20a can be shortened.

  As shown in FIGS. 4 and 5, in step S1, the structural members of the tire 2 shown in FIG. 2 (in this embodiment, the rubber portion 11, the bead core 5, the carcass ply 6A, and the belt plies 7A to 7D). Is modeled with element F (i). As a result, the constituent members of the three-dimensional tire model 20a (in this embodiment, the rubber portion 21, the bead core model 22, the carcass ply model 23A, and the belt ply models 24A to 24D) are set.

  The rubber portion 21 includes a tread rubber 21a modeled on the tread rubber 11a (shown in FIG. 2), a sidewall rubber 21b modeled on the sidewall rubber 11b (shown in FIG. 2), and a clinch rubber 11c (shown in FIG. 2). ) Is modeled. Further, the rubber portion 21 includes a bead apex rubber 21d that models the bead apex rubber 11d (shown in FIG. 2), and an inner liner rubber 21e that models the inner liner rubber 11e (shown in FIG. 2). .

  Such model setting (modeling) can be easily performed by using, for example, meshing software as in the conventional method. By sequentially setting the rubber part 21, the bead core model 22, the carcass ply model 23A, and the belt ply models 24A to 24D, a three-dimensional tire model 20a is set.

  The outer surface of the tire 2 shown in FIG. 2 is reproduced on the outer surface of the three-dimensional tire model 20a. That is, the tread contact surface 26, the groove 27, the rim contact surface 28, and the side surface 29 are set on the outer surface of the three-dimensional tire model 20a. Each region of the tread contact surface 26, the groove 27, the rim contact surface 28, and the side surface 29 is classified based on the normal state of the tire 2 shown in FIG. In the three-dimensional tire model 20a, a tire lumen surface 30s on which the tire lumen surface 10s (shown in FIG. 2) of the tire 2 is reproduced is set.

  As described above, a lateral groove (not shown) is not formed in the three-dimensional tire model 20a of the present embodiment. For this reason, as the groove 27 of the three-dimensional tire model 20a, only the main groove 27A that models the main groove 13A of the tire 2 shown in FIG. 2 is set. The main groove 27A includes a center main groove 27Aa and a shoulder main groove 27Ab. A center land portion 32a, a middle land portion 32b, and a shoulder land portion 32c are set on the tread ground surface 26.

  In step S1 of the present embodiment, a two-dimensional tire model 20b formed from a meridian cross section including the tire rotation shaft 25 (shown in FIG. 3) is set based on the three-dimensional tire model 20a. In FIG. 5, a three-dimensional tire model 20a and a two-dimensional tire model 20b are displayed in common. In addition, although the two-dimensional tire model 20b of this embodiment is set based on the three-dimensional tire model 20a, it is not necessarily limited to such an aspect. The two-dimensional tire model 20b may be directly modeled based on the contour of the tire 2, for example.

  FIG. 6 is an enlarged view of the tread rubber 21a of the tire model shown in FIG. The two-dimensional tire model (hereinafter sometimes simply referred to as “tire model”) 20 b of the present embodiment includes a non-recessed region 36 that is a portion other than the recessed portion 18 in the rubber portion 21, and a recessed portion 18. And the recessed area 37 which has been defined. The case where it is the horizontal groove 13B provided in the tread rubber 11a is illustrated as the recessed part 18 in which the recessed part area | region 37 of this embodiment is set. The recessed area 37 is set based on, for example, the shape of the lateral groove 13B of the tire 2 acquired from design data (for example, CAD data) of the vulcanization mold. In FIG. 6, the recessed area 37 is colored and displayed.

  The recessed region 37 includes a center lateral groove region 37a that is a portion of the center lateral groove 13Ba (shown in FIG. 2) of the tire 2, a middle lateral groove region 37b that is a portion of the middle lateral groove 13Bb (shown in FIG. 2) of the tire 2, and the tire. A shoulder lateral groove region 37c, which is a portion of two shoulder lateral grooves 13Bc (shown in FIG. 2), is included. These recessed regions (lateral groove regions) 37a, 37b, and 37c are specified by, for example, coordinate values of the two-dimensional tire model 20b. The three-dimensional tire model 20a and the two-dimensional tire model 20b are stored in the computer 1.

  Next, in the creation method of the present embodiment, the heat transfer coefficient is defined on the outer surface of the tire model 20b and the tire cavity surface in the computer 1 (heat transfer coefficient defining step S2). In the heat transfer coefficient defining step S2 of the present embodiment, the heat transfer coefficient is set in the two-dimensional tire model 20b. FIG. 7 is a flowchart illustrating an example of a processing procedure of the heat transfer coefficient defining step.

  In the heat transfer coefficient defining step S2 of the present embodiment, first, the heat transfer coefficient between the outer surface of the tire model 20b and the outside air (not shown) is defined (step S21). In this embodiment, as shown in FIG. 5, the heat transfer coefficient between the tread ground surface 26 and the outside air, the heat transfer coefficient between the main groove 27 </ b> A and the outside air, and between the side face 29 and the outside air. Heat transfer coefficient is defined. These heat transfer coefficients are, for example, measured values of actual running tests of the tire 2 in consideration of heat radiation to the outside of the tread ground surface 12, the main groove 13A, and the side surface 17 of the tire 2 shown in FIG. , Based on the calculation results of a simulation performed in advance using a tire model. The heat transfer coefficients set in the tread ground surface 26, the main groove 27A, and the side surface 29 are stored in the computer 1.

  Next, in the heat transfer coefficient defining step S2, the heat transfer coefficient between the tread ground surface 26 and the road surface (not shown) is defined (step S22). Further, a heat transfer coefficient between the tire lumen surface 30s and the tire lumen 30 is defined (step S23). Furthermore, the heat transfer coefficient between the rim contact surface 28 and the rim (not shown) is defined (step S24). These heat transfer coefficients are also the same as those of the tread contact surface 12 shown in FIG. 2 to the road surface, the heat release of the tire lumen surface 10s to the tire lumen 10, and the rim R of the rim contact surface 16 shown in FIG. In consideration of heat radiation to the tire, for example, it is defined on the basis of an actual measurement value of a running test of the actual tire 2 or the like. These heat transfer coefficients are also stored in the computer 1.

  Next, in the creation method of the present embodiment, the thermal conductivity is defined for each element F (i) of the tire model 20 in the computer 1 (thermal conductivity defining step S3). In the thermal conductivity defining step S3 of the present embodiment, the thermal conductivity is set in the two-dimensional tire model 20b. FIG. 8 is a flowchart showing an example of the processing procedure of the thermal conductivity defining step S3 of the present embodiment.

  In the thermal conductivity defining step S3 of the present embodiment, first, as shown in FIG. 5, the constituent members of the tire model 20b excluding the rubber portion 21 (the tread rubber 21a in the present embodiment) in which the recessed region 37 is set. The thermal conductivity is respectively defined (step S31).

  In step S31, based on the thermal conductivity of each component of the tire 2 shown in FIG. 2 (in this embodiment, the rubber portion 11, the bead core 5, the carcass ply 6A, and the belt plies 7A to 7D), the tire model 20b The thermal conductivity of each component (in this embodiment, rubber part 21, bead core model 22, carcass ply model 23A, and belt ply models 24A to 24D) is defined. Similarly, thermal conductivity is defined for each of the sidewall rubber 21b, the clinch rubber 21c, the bead apex rubber 21d, and the inner liner rubber 21e of the tire model 20b. These thermal conductivities are stored in the computer 1.

  Next, in the thermal conductivity defining step S3 of the present embodiment, as shown in FIG. 6, the non-recessed region 36 of the rubber portion 21 (the tread rubber 21a in the present embodiment) in which the recessed region 37 is set. The first thermal conductivity is defined for the element F (i) (step S32). The first thermal conductivity is defined based on the thermal conductivity of the tread rubber 21a of the tire 2 shown in FIG. The first thermal conductivity is stored in the computer 1.

  Next, in the thermal conductivity defining step S3 of the present embodiment, in the rubber portion 21 (the tread rubber 21a in the present embodiment) in which the concave region 37 is set, the concave region 37 (colored and displayed in FIG. 6) is displayed. The second thermal conductivity larger than the first thermal conductivity is defined in at least a part of the element F (i) (second thermal conductivity defining step S33).

  In the tire 2 shown in FIG. 2, the rubber portion 11 (in this embodiment, the tread rubber 11a) is a portion where the concave portion 18 (in this embodiment, the lateral groove 13B) is formed, and the rubber portion 11 is in contact with air. The area is increased, and the heat dissipation amount of the rubber portion 11 is partially increased. For this reason, the temperature of the part in which the recessed part 18 is formed among the rubber parts 11 becomes small compared with the temperature of the part in which the recessed part 18 is not formed.

  Based on such a viewpoint, as shown in FIG. 6, at least a part of the element F (i) of the recessed region 37 that is the recessed portion 18 (in this embodiment, the lateral groove 13B) has a first thermal conductivity. A second thermal conductivity greater than is defined. Thereby, even if the tire model 20b does not have a lateral groove, a temperature calculation in consideration of the heat dissipation of the lateral groove 13B of the tire 2 can be performed in a simulation described later. In the present embodiment, the second thermal conductivity is set for all of the center lateral groove region 37a, the middle lateral groove region 37b, and the shoulder lateral groove region 37c.

  The second thermal conductivity can be appropriately set as long as it is higher than the first thermal conductivity. The second thermal conductivity is preferably set based on, for example, the structure of the tire 2 shown in FIG. The second thermal conductivity is stored in the computer 1.

  The tire model 20b created through the steps S1 to S3 can be used for calculation of a physical quantity related to the temperature of the tire 2 (shown in FIG. 2) in a simulation using the computer 1. Moreover, in the tire model 20b, the element F (i) of the recessed region 37 that is the recessed portion 18 (the lateral groove 13B in the present embodiment) of the tire 2 shown in FIG. 2 Thermal conductivity is defined. For this reason, even if the tire model 20b does not have a recess (in this embodiment, a lateral groove), it is possible to perform a temperature calculation in consideration of the heat dissipation of the recess 18 (in this embodiment, the lateral groove 13B) of the tire 2. Become.

  Next, a tire temperature simulation method using the tire model created by the creation method of the present embodiment (hereinafter sometimes simply referred to as “simulation method”) will be described. In the simulation method of the present embodiment, a physical quantity related to the temperature of the tire model is calculated using the computer 1. FIG. 9 is a flowchart illustrating an example of a processing procedure of the simulation method of the present embodiment.

  In the simulation method of this embodiment, first, a road surface model in which the road surface (not shown) on which the tire 2 (shown in FIG. 2) rolls is modeled with a finite number of elements is input to the computer 1 (step S4). ).

  As shown in FIG. 4, the road surface model 38 is modeled by, for example, an element H of a rigid surface that forms a single plane. Thereby, the road surface model 38 is defined so as not to be deformed even when an external force is applied. Then, numerical data of the element H constituting the road surface model 38 is stored in the computer 1.

  The road surface model 38 may be formed on a cylindrical surface like a drum tester, for example. Further, the road surface model 38 may be provided with a step, a depression, a swell, a ridge, or the like as necessary.

  Next, in the simulation method of the present embodiment, boundary conditions are defined in the tire model in the computer 1 (boundary condition setting step S5). In the boundary condition setting step S5, boundary conditions for rolling the three-dimensional tire model 20a to the road surface model 38 and boundary conditions for use in heat transfer calculation of the two-dimensional tire model 20b are defined. FIG. 10 is a flowchart showing an example of the processing procedure of the boundary condition setting step S5.

  In the boundary condition setting step S5, first, conditions for bringing the three-dimensional tire model 20a shown in FIG. 4 into contact with the road surface model 38 are set (step S51). In step S51, as in the conventional simulation method, for example, the internal pressure condition, rim condition, load load condition, camber angle, or static friction coefficient of the three-dimensional tire model 20a are set as appropriate. Such a condition is stored in the computer 1.

  Next, in the boundary condition setting step S5, conditions for performing rolling calculation of the three-dimensional tire model 20a are set (step S52). Similarly to the conventional simulation method, this step S52 is also, for example, the slip angle of the three-dimensional tire model 20a shown in FIG. 4, the traveling speed Vs, or between the three-dimensional tire model 20a and the road surface model 38. A dynamic friction coefficient and the like are appropriately set. Such a condition is stored in the computer 1.

  Next, in the boundary condition setting step S5, a predetermined temperature of the outside air and a temperature of the tire lumen 30 (shown in FIG. 5) are set in the two-dimensional tire model 20b (step S53). The temperature of the outside air and the temperature of the tire lumen 30 can be appropriately set based on the running conditions of the tire 2 and the like. These conditions are stored in the computer 1.

  Next, in the simulation method of the present embodiment, the computer 1 calculates a physical quantity related to the temperature of the tire model based on a predetermined condition and thermal conductivity (calculation step S6). In the calculation step S6 of the present embodiment, the temperature of the tire model during traveling is calculated as a physical quantity related to the temperature of the tire model. FIG. 11 is a flowchart illustrating an example of a processing procedure of the calculation step S6 of the present embodiment.

  In the calculation step S6 of the present embodiment, first, the shape after the internal pressure filling of the three-dimensional tire model 20a is calculated (step S61). In step S61, first, as shown in FIG. 5, the rim contact surfaces 28, 28 of the three-dimensional tire model 20a are restrained so as not to be deformed. Next, the bead portion 31 is forcibly displaced so that the width W1 of the bead portion 31 of the three-dimensional tire model 20a is equal to the rim width of the rim R (shown in FIG. 2). Next, the bead portion 31 is forcibly displaced so that the distance Rs in the tire radial direction and the rim diameter between the tire rotation shaft 25 (shown in FIG. 4) of the three-dimensional tire model 20a and the bottom surface of the bead portion 31 are equal. The Further, deformation calculation is performed on the three-dimensional tire model 20a based on the evenly distributed load w corresponding to the internal pressure condition. Thereby, in process S61, the three-dimensional tire model 20a after internal pressure filling is calculated. The three-dimensional tire model 20a after such internal pressure filling is stored in the computer 1.

  In the deformation calculation of the three-dimensional tire model 20a, a mass matrix, a stiffness matrix, and a damping matrix are created for each element F (i) based on the shape and material characteristics of each element. Furthermore, each of these matrices is combined to create a matrix for the entire system. Then, the computer 1 applies the above-mentioned various conditions to create an equation of motion, which is a three-dimensional tire model every unit time T (x) (x = 0, 1,...) (For example, every 1 μsec). The deformation calculation of 20a is performed. Such deformation calculation can be performed using, for example, commercially available finite element analysis application software such as LS-DYNA manufactured by LSTC.

  Next, in the calculation step S6 of the present embodiment, a load is defined in the three-dimensional tire model 20a after the internal pressure filling (step S62). In this step S62, first, as shown in FIG. 4, the contact between the three-dimensional tire model 20a after the internal pressure filling and the road surface model 38 is calculated. Next, in step S62, deformation of the three-dimensional tire model 20a is calculated based on a predetermined load T (load condition set as a boundary condition). As a result, in step S62, the three-dimensional tire model 20a in contact with the road surface model 38 is calculated. The three-dimensional tire model 20a that contacts the road surface model 38 is stored in the computer 1.

  Next, in the calculation step S6 of the present embodiment, a state in which the three-dimensional tire model 20a rolls on the road surface model 38 is calculated based on a predetermined traveling speed Vs (step S63). In this step S63, first, as shown in FIG. 4, an angular velocity Va corresponding to the traveling velocity Vs is defined in the three-dimensional tire model 20a. Next, a translation speed Vt corresponding to the travel speed Vs is defined in the road surface model 38. The translation speed Vt is the speed at the tread contact surface 26 between the three-dimensional tire model 20a and the road surface model 38. Based on these conditions, a three-dimensional tire model 20a that rolls on the road surface model 38 is calculated.

  Next, in the calculation step S6 of the present embodiment, the amount of heat generated when the three-dimensional tire model 20a is traveling is calculated (step S64). In step S64 of this embodiment, the amount of heat generated during traveling is calculated based on the three-dimensional tire model 20a that rolls on the road surface model 38. In step S64, similarly to the conventional method, in each rubber portion 21 shown in FIG. 5, the distortion of each element F (i) calculated in step S63 and the loss tangent tan δ of each element F (i) are calculated. Using this, the calorific value of each element F (i) is calculated every unit time T (x). The initial value of tan δ can be appropriately set based on the traveling speed Vs. Such a calorific value can be easily calculated by using the above application. The amount of heat generated by each element F (i) is stored in the computer 1.

  Next, in the calculation step S6 of the present embodiment, the heat dissipation amount during travel of the tire model is calculated (step S65). In this step S65, a two-dimensional tire model 20b is used.

  In step S65, first, similarly to the conventional method, the heat transfer coefficient, the temperature of the outside air, and the heat of each element F (i) set on the outer surface of the two-dimensional tire model 20b and the tire lumen surface 30s, respectively. Based on the conductivity, the heat dissipation amount of each element F (i) is calculated every unit time T (x). The calculation of the heat release amount of the present embodiment can be easily calculated using the above application without performing a fluid simulation modeling air (fluid). The amount of heat released from each element F (i) is stored in the computer 1.

  As described above, in the two-dimensional tire model 20b of the present embodiment, as shown in FIG. 6, the first thermal conductivity is defined for the element F (i) of the non-recessed region 36, and A second thermal conductivity larger than the first thermal conductivity is defined for the element F (i) of the recessed region 37. Thereby, in step S65, even if a recess (lateral groove in the present embodiment) is not set in the tread rubber 21a of the tire model 20b, the heat dissipation of the recess 18 (lateral groove 13B in the present embodiment) of the tire 2 is taken into consideration. Thus, the heat dissipation amount of the tire model 20b can be calculated.

  Next, in the calculation step S6 of the present embodiment, the temperature during travel of the tire model 20b is calculated based on the heat generation amount and the heat dissipation amount (step S66). In this step S66, first, the calorific value of each element F (i) of the three-dimensional tire model 20a calculated every unit time T (x) is arranged on a cross section corresponding to the two-dimensional tire model 20b. In addition, the heat generation amount of each element F (i) is specified. Then, by calculating the heat balance between the specified heat generation amount and the heat dissipation amount of each element F (i) of the two-dimensional tire model 20b, each element F (i) when the tire model 20b is traveling is calculated. Is calculated every unit time. The temperature when the tire model 20b is traveling is stored in the computer 1.

  In the calculation step S6 of the present embodiment, in step S65, since the heat dissipation amount of the tire model 20b considering the heat dissipation of the lateral groove 13B (shown in FIG. 2) is calculated, the temperature during travel of the tire model 20b is accurately determined. Can be sought. Further, in the calculation step S6, the calorific value of the three-dimensional tire model 20a in which the tread rubber 21a is not provided with a lateral groove (not shown) is calculated. For example, the tread rubber 21a is provided with a lateral groove (not shown). The calculation can be simplified as compared with the case where a tire model (not shown) is used. Therefore, the simulation method of this embodiment can reduce the calculation time.

  Next, in calculation step S6 of the present embodiment, it is determined whether or not a predetermined rolling end time has elapsed (step S67). In this step S67, when it is determined that the rolling end time has elapsed (“Y” in step S67), a series of processing of the calculation step S6 is completed, and the next step S7 is performed. On the other hand, when it is determined that the rolling end time has not elapsed ("N" in step S67), the temperature of each element F (i) of the two-dimensional tire model 20b is updated (step S68). . Furthermore, the unit time T (x) is advanced by one (step S69), and steps S63 to S67 are performed again.

  Thus, in calculation process S6, the temperature at the time of driving | running | working of the tire model 20b from rolling start to rolling end can be memorize | stored for every unit time T (x). Note that the rolling end time can be appropriately set according to the simulation to be executed.

  Next, in the simulation method of the present embodiment, it is determined whether or not the physical quantity related to the temperature of the tire model is within an allowable range (step S7). In the present embodiment, it is determined whether or not the temperature during running of the tire model is within an allowable range. The allowable range can be set as appropriate according to the performance required for the tire 2.

  In step S7, when the temperature during running of the tire model 20b is within an allowable range (“Y” in step S7), the tire 2 is manufactured based on the three-dimensional tire model 20a or the two-dimensional tire model 20b. (Step S8). On the other hand, when the temperature during running of the tire model 20b is not within the allowable range ("N" in step S7), after the tire 2 is redesigned (step S9), the creation method (step S1) shown in FIG. To Step S3) are performed, and the simulation method (Step S4 to Step S8) is performed again. As described above, in the simulation method of the present embodiment, since the design of the tire 2 is changed until the temperature during traveling of the tire model 20b falls within the allowable range, the tire 2 having excellent durability is efficiently designed. be able to.

  As shown in FIG. 6, in the present embodiment, the mode in which the second thermal conductivity is set in all of the center lateral groove region 37a, the middle lateral groove region 37b, and the shoulder lateral groove region 37c is exemplified, but the present invention is not limited thereto. It is not done. For example, the second thermal conductivity may be set only in one of the recessed regions 37 among the center lateral groove region 37a, the middle lateral groove region 37b, and the shoulder lateral groove region 37c.

  As shown in FIG. 2, the center lateral groove 13Ba and the middle lateral groove 13Bb of the tire 2 mainly exchange heat with the outside air on the tread ground surface 12 side. On the other hand, the shoulder lateral groove 13Bc exchanges heat with both the outside air on the tread ground surface 12 side and the outside air on the side surface 17 side. For this reason, the heat radiation amount in the shoulder lateral groove 13Bc is larger than the heat radiation amounts in the center lateral groove 13Ba and the middle lateral groove 13Bb. Further, the outer ends of the belt plies 7A to 7C in the tire axial direction are disposed inside the shoulder lateral grooves 13Bc in the tire radial direction. At the outer ends of such belt plies 7A to 7C, large distortion is likely to occur during tire travel, so that the temperature of the shoulder land portion 14c is larger than the temperature of the center land portion 14a and the temperature of the middle land portion 14b. Prone. Since the temperature of the shoulder land portion 14c is important for evaluating the durability of the tire 2, it is necessary to obtain the temperature more accurately than the temperature of the center land portion 14a and the temperature of the middle land portion 14b.

  Based on such a viewpoint, the second thermal conductivity may be set only in the shoulder lateral groove region 37c. In this case, the same first heat conductivity as that of the other tread rubber 21a is defined in the center lateral groove region 37a and the middle lateral groove region 37b. Thereby, in the process S65 of calculating the heat dissipation amount of the tire model 20b, the area calculated based on the second thermal conductivity is limited to the shoulder lateral groove area 37c, so that the calculation time can be shortened. And since the temperature of the shoulder land part 14c important for evaluating the durability of the tire 2 can be calculated accurately, the calculation accuracy of the tire temperature can be maintained.

  By the way, in the second thermal conductivity defining step S33 shown in FIG. 8, when the second thermal conductivity set in the recessed area 37 is defined according to, for example, an empirical rule of the operator, it is calculated in the calculating step S6. There is a possibility that the temperature during running of the tire model 20b (shown in FIG. 5) and the actual temperature of the tire 2 (shown in FIG. 2) cannot be sufficiently approximated. Further, the tire model 20b (or the tire model 20a) that cannot sufficiently approximate the temperature of the actual tire 2 is used, and a plurality of conditions (for example, the traveling speed Vs or the depth of the recessed portion 37, etc.) The difference between the temperature of the tire model 20b calculated in (1) and the temperature of the actual tire 2 (shown in FIG. 2) measured under these conditions is likely to vary. For this reason, it is difficult to approximate the temperature of the tire model to the temperature of a portion (for example, a portion that can be a starting point of damage) to be most evaluated among the components of the tire 2 that actually traveled.

  For this reason, in the second thermal conductivity defining step S33, based on the temperature of the most desired portion of the constituent members of the tire 2 that has actually traveled (hereinafter sometimes referred to as “evaluation target portion”). It is desirable that two thermal conductivities be defined. FIG. 12 is a flowchart illustrating an example of a processing procedure of the second thermal conductivity definition step S33 according to another embodiment of the present invention. In this embodiment, the same components as those of the previous embodiment are denoted by the same reference numerals and description thereof may be omitted. Note that the three-dimensional tire model 20a and the two-dimensional tire model 20b used in the second thermal conductivity defining step S33 of this embodiment are independent of the tire models 20a and 20b used in the simulation method of the previous embodiment. Prepared.

  In the second thermal conductivity defining step S33 of this embodiment, an example of defining the second thermal conductivity set in the shoulder lateral groove region 37c among the center lateral groove region 37a, the middle lateral groove region 37b, and the shoulder lateral groove region 37c is illustrated. To explain. The second thermal conductivity of the center lateral groove region 37a, the middle lateral groove region 37b, and the shoulder lateral groove region 37c may be respectively defined.

  In the second thermal conductivity defining step S33 of this embodiment, first, the tire 2 is run under predetermined running conditions, and the temperature of the evaluation target portion is measured (step S331). In step S331 of this embodiment, first, the tire 2 shown in FIG. 2 is assembled to the normal rim R to fill the normal internal pressure. Next, based on a predetermined speed (for example, 80 km / h), the tire 2 filled with the internal pressure is caused to travel with a drum tester (for example, a diameter of 1.7 m). Next, measurement is performed until the temperature of the evaluation target portion does not change. Then, the temperature of the evaluation target portion that has become constant is stored in the computer 1.

  Next, in the second thermal conductivity defining step S33 of this embodiment, the second thermal conductivity of at least part of the element F (i) of the recessed region 37 of the tire model 20b shown in FIGS. An initial value (hereinafter simply referred to as “initial value”) is defined (step S332). In this step S332, as shown in FIG. 5, in the heat transfer coefficient defining step S2 (shown in FIG. 3), the heat transfer rate defining step S31 and the step S32 in the heat conductivity defining step S3 (shown in FIG. 7), A two-dimensional tire model 20b in which the thermal conductivity of the constituent members of the tire model 20b excluding the tread rubber 21a and the first thermal conductivity is defined is used. And as FIG. 6 shows, an initial value is set only to the recessed part area | region 37 (this embodiment shoulder lateral groove area | region 37c) by which the setting of 2nd thermal conductivity is planned.

  The initial value can be appropriately set as long as it is larger than the first thermal conductivity. The initial value of this embodiment is desirably about 1.1 to 2.0 times the first thermal conductivity, for example. Such initial values are stored in the computer 1. In this embodiment, the same first heat conductivity as that of the non-recessed region 36 is defined in the center lateral groove region 37a and the middle lateral groove region 37b in which the initial value is not set.

  Next, in the second thermal conductivity defining step S33 of this embodiment, boundary conditions are defined for the tire model in the computer 1 (step S333). In step S333, the same processing procedure as that in the boundary condition setting step S5 shown in FIG. 10 is performed. Therefore, the three-dimensional tire model 20a shown in FIG. 4 includes an internal pressure condition, a rim condition, a load load condition, a camber angle, a static friction coefficient, a slip angle, a running speed Vs, an outside air temperature, or a tire lumen 30. Boundary conditions including temperature etc. are set respectively. The traveling speed Vs is set to a traveling speed (for example, 80 km / h) when the tire 2 is traveling. In step S333, the initial value of the temperature of the element F (i) of the tire model 20b is set.

  Next, in the second thermal conductivity defining step S33 of this embodiment, a state in which the three-dimensional tire model 20a rolls on the road surface model 38 is calculated based on a predetermined traveling speed Vs (step). S334). In step S334, first, according to the processing procedure similar to steps S61 and S62 of calculation step S6 shown in FIG. 11, as shown in FIG. 4, the shape after filling the internal pressure of the three-dimensional tire model 20a, and the road surface The shape after contact with the model 38 is calculated. Then, a three-dimensional tire model 20a that rolls on the road surface model 38 is calculated according to the same processing procedure as in step S63 of the calculation step S6.

  Next, in the second thermal conductivity defining step S33 of this embodiment, the amount of heat generated when the three-dimensional tire model 20a is traveling is calculated (step S335). Step S335 is performed by the same processing procedure as step S64 of calculation step S6 shown in FIG. Accordingly, in step S335, as shown in FIG. 4, the amount of heat generated by each element F (i) of the three-dimensional tire model 20a that rolls at a traveling speed (for example, 80 km / h) when the tire 2 travels. Is calculated every unit time T (x). The amount of heat generated by each element F (i) is stored in the computer 1.

  Next, in the second thermal conductivity defining step S33 of this embodiment, the amount of heat released during traveling of the tire model 20b is calculated (step S336). In step S336, a two-dimensional tire model 20b (shown in FIG. 5) in which an initial value of the second thermal conductivity is set is used. Step S336 is performed by the same processing procedure as step S65 of calculation step S6 shown in FIG. Accordingly, in step S336, the heat release amount of each element F (i) of the two-dimensional tire model 20b is calculated for each unit time T (x) based on the heat release performance of the lateral groove 13B considered by the initial value. The The amount of heat generated by each element F (i) is stored in the computer 1.

  Next, in the second thermal conductivity defining step S33 of this embodiment, the temperature during travel of the tire model 20b is calculated based on the heat generation amount and the heat dissipation amount (step S337). In this step S337, the temperature of each element F (i) at the time of traveling of the two-dimensional tire model 20b is calculated for each unit time based on the processing procedure similar to step S66 of the calculation step S6 shown in FIG. Calculated. The temperature of each element F (i) when the two-dimensional tire model 20b is traveling is stored in the computer 1.

  Next, in the second thermal conductivity defining step S33 of this embodiment, it is determined whether or not the temperature of each element F (i) of the two-dimensional tire model 20b has converged (step S338). In step S338, for all the elements F (i), the temperature of the element F (i) of the two-dimensional tire model 20b calculated in step S337 and the element F (i) of the two-dimensional tire model 20b before calculation. Is determined (ie, the temperature of the element F (i) set in step S333) has converged below a predetermined temperature difference.

  When it is determined in step S338 that the temperature of each element F (i) of the two-dimensional tire model 20b has converged (“Y” in step S338), each element F (i) of the two-dimensional tire model 20b Can be treated as the temperature when the tire is traveling (that is, when traveling at a preset traveling speed Vs). In this case, the next step S339 is performed.

  On the other hand, when it is determined in step S338 that the temperature of each element F (i) of the two-dimensional tire model 20b has not converged (“N” in step S338), each element of the two-dimensional tire model 20b The temperature of F (i) cannot be treated as the temperature during tire traveling (that is, when traveling at a preset traveling speed Vs). In this case, the temperature of each element F (i) of the two-dimensional tire model 20b (that is, the temperature of the element F (i) set in step S333) is the same as that of the two-dimensional tire model 20b calculated in step S337. The temperature of each element F (i) is updated (step S340). Further, the unit time T (x) is advanced by one (step S341), and steps S334 to S338 are performed again based on the temperature of each element F (i) of the updated two-dimensional tire model 20b. .

  Thus, in the simulation method of this embodiment, since the temperature of each element F (i) of the two-dimensional tire model 20b can be converged, the tire 2 that rolls at a traveling speed (for example, 80 km / h). Can be calculated with high accuracy. The determination as to whether or not the temperature of each element F (i) of the two-dimensional tire model 20b has converged is preferably based on whether or not the temperature difference is less than 1.0 ° C., for example. .

  Next, in the second thermal conductivity defining step S33 of this embodiment, the temperature of the evaluation target portion during traveling of the tire 2 and the portion corresponding to the evaluation target portion of the two-dimensional tire model 20b (hereinafter simply referred to as “evaluation”). It is determined whether or not the difference between the target portion and the temperature is within an allowable range (step S339). The allowable range is appropriately set according to the required calculation accuracy.

  In step S339, when it is determined that the difference between the temperature of the evaluation target portion of the tire 2 and the temperature of the evaluation target portion of the two-dimensional tire model 20b is within an allowable range (“Y” in step S339), The evaluation target portion of the tire model 20b calculated based on the initial value of the second thermal conductivity approximates the temperature of the evaluation target portion of the actual tire 2 (shown in FIG. 2). In this case, the initial value of the second thermal conductivity (including the value updated in step S343 described later) is determined as the second thermal conductivity set in the two-dimensional tire model 20b (step S342).

  Since the second thermal conductivity is defined based on the temperature of the evaluation target portion of the tire 2 that actually traveled, the evaluation target portion of the tire model 20b (shown in FIG. 5) calculated in the calculation step S6. And the temperature of the evaluation target portion of the actual tire 2 (shown in FIG. 2) can be reliably approximated. Therefore, even when the tire model 20b in which the second heat transfer coefficient is set is used and the tire model 20b is calculated under a plurality of conditions (for example, the traveling speed Vs or the depth of the recessed portion 37), the tire Variation in error between the temperature of the evaluation target portion of the model 20b and the temperature of the actual evaluation target portion of the tire 2 measured under these conditions can be reduced. Therefore, the second thermal conductivity defining step S33 of this embodiment is useful for improving the simulation accuracy.

  On the other hand, when it is determined that the difference between the temperature of the evaluation target portion of the two-dimensional tire model 20b and the temperature of the evaluation target portion of the tire 2 is not within the allowable range ("N" in step S339), the second heat The temperature of the evaluation target portion of the tire model 20b calculated based on the initial value of the conductivity and the temperature of the evaluation target portion of the actual tire 2 (shown in FIG. 2) are not sufficiently approximate. Therefore, the initial value of the second thermal conductivity is updated (Step S343), and Steps S333 to S339 are performed again.

  The update of the initial value of the second thermal conductivity in step S343 is performed when the temperature of the evaluation target portion of the two-dimensional tire model 20b is higher than the temperature of the evaluation target portion of the tire 2. Reduce the initial value of. Conversely, when the temperature of the evaluation target portion of the two-dimensional tire model 20b is lower than the temperature of the evaluation target portion of the tire 2, the initial value of the second thermal conductivity is increased. Thereby, in 2nd thermal conductivity definition process S33 of this embodiment, the 2nd thermal conductivity which can approximate the temperature of the evaluation object part of the tire model 20b to the temperature of the evaluation object part of the tire 2 is defined reliably. be able to.

  In the previous embodiment, the second thermal conductivity was determined based on the temperature of the evaluation target portion of the tire 2 that actually traveled. However, the present invention is not limited to such a mode. For example, a relational expression between the second thermal conductivity and a factor related to heat dissipation of the recess 18 (hereinafter, simply referred to as “heat dissipation factor”) is obtained in advance, and this relational expression and the recess 18 (this embodiment). Then, the second thermal conductivity may be determined based on the heat release factor of the lateral groove 13B). The heat dissipation factor of the recess 18 can be appropriately set as long as it affects the heat dissipation performance of the recess 18. Examples of the heat release factor of the concave portion 18 of the present embodiment include a case where the width of the lateral groove 13B in the tire circumferential direction is (mm) and the number of pitches (pieces) of the lateral groove 13B in the tire circumferential direction.

  FIG. 13 is a flowchart illustrating an example of a processing procedure of the second thermal conductivity defining step S33 according to still another embodiment of the present invention. In this embodiment, the same components as those of the previous embodiment are denoted by the same reference numerals and description thereof may be omitted. Note that the three-dimensional tire model 20a and the two-dimensional tire model 20b used in the second thermal conductivity defining step S33 of this embodiment are independent of the tire models 20a and 20b used in the simulation method of the previous embodiment. Prepared.

  In the second thermal conductivity defining step S33 of this embodiment, the second thermal conductivity defined in the shoulder lateral groove region 37c among the center lateral groove region 37a, the middle lateral groove region 37b, and the shoulder lateral groove region 37c is defined. An example will be described. The second thermal conductivity of the center lateral groove region 37a, the middle lateral groove region 37b, and the shoulder lateral groove region 37c may be respectively defined.

  In the second thermal conductivity defining step S33 of this embodiment, first, a first relationship between the volume ratio and surface area ratio of the recess 18 (in this embodiment, the lateral groove 13B) and the temperature of the evaluation target portion of the tire 2 is shown. A relational expression is defined (first relational expression defining step S36). The volume ratio and the surface area ratio of the lateral groove 13B are determined from the heat release factor of the lateral groove 13B (in this embodiment, the groove width and the number of pitches of the lateral groove 13B). FIG. 14 is a flowchart illustrating an example of a processing procedure of the first relational expression definition step S36.

  In the first relational expression definition step S36 of this embodiment, first, a plurality of tires 2 having different heat dissipation factors (in this embodiment, the groove width and the number of pitches of the lateral grooves 13B) of the recesses 18 are prepared (step S361). . The range in which the groove width and the pitch number of the lateral grooves 13B are made different can be set as appropriate according to the tire category. The groove width of the lateral groove 13B is desirably different within the range of the lateral groove 13B that can be set as a product. Similarly, it is desirable that the number of pitches of the lateral grooves 13B is varied within the range of the number of pitches of the lateral grooves 13B that can be set as a product. Further, in order to obtain the first relational expression with high accuracy, the number of samples of the tire 2 is preferably as large as possible.

  Next, in the first relational expression defining step S36 of this embodiment, a plurality of tires 2 having different heat release factors (in this embodiment, the groove width and the number of pitches of the lateral grooves 13B) of the recesses 18 are determined in advance. The temperature of the part to be evaluated when traveling under traveling conditions (that is, the part most desired to be evaluated among the constituent members of the actually traveled tire 2) is measured (step S362). In step S362 of this embodiment, first, the tires 2 shown in FIG. 2 are assembled to the regular rim R to fill the regular internal pressure. Next, in step S362, the tire 2 filled with the internal pressure is drum tested on the basis of one traveling speed selected from the traveling speeds (in this embodiment, 70 km / h, 80 km / h, 90 km / h). (For example, the diameter is 1.7 m). Next, in step S362, measurement is performed until the temperature of the evaluation target portion does not change, and the constant temperature of the evaluation target portion is stored.

  Furthermore, in step S362 of the present embodiment, for each tire 2 having a different heat release factor of the lateral groove 13B, the evaluation target portion at other travel speeds (70 km / h, 80 km / h, 90 km / h in this embodiment) The temperature is measured in the same way. As a result, the heat dissipation factor of the lateral groove 13B (in this embodiment, the groove width and the number of pitches of the lateral groove 13B) and the temperature of the evaluation target portion of each tire 2 with different running speeds are measured and stored in the computer 1. The

Next, in the first relational expression defining step S36 of this embodiment, a first relationship indicating the relationship between the volume ratio and the surface area ratio of the recess 18 (in this embodiment, the lateral groove 13B) and the temperature of the evaluation target portion of the tire 2 is shown. A relational expression is obtained (step S363). As described above, the volume ratio and the surface area ratio of the horizontal groove 13B are determined from the heat release factor of the horizontal groove 13B (in this embodiment, the groove width and the number of pitches of the horizontal groove 13B). In step S363, the volume ratio and the surface area of the lateral groove 13B and the temperature of the evaluation target portion of the tire 2 are subjected to multiple regression analysis, whereby the volume ratio x1 and the surface area ratio x2 of the recess 18 (the lateral groove 13B in the present embodiment). In addition, a first relational expression (in this embodiment, a regression expression) indicating the temperature relation of the evaluation target portion of the tire 2 is obtained. The first relational expression is shown in the following expression (1). Such a first relational expression can uniquely calculate the temperature of the evaluation target portion of the tire 2 by substituting the volume ratio and the surface area ratio of the concave portion 18 (the lateral groove 13B in the present embodiment). The first relational expression is stored in the computer 1.
Ta = f (x1, x2) (1)
here,
Ta: Temperature of the evaluation target portion of the tire x1: Volume ratio of the recess x2: Surface area ratio of the recess

  Next, in the second thermal conductivity defining step S33 of this embodiment, the second thermal conductivity set in the recessed region 37 of the tire model 20b and the temperature of the evaluation target portion during traveling of the two-dimensional tire model 20b. Are defined (second relational expression defining step S37). The second relational expression is for obtaining the temperature of the evaluation target portion when the tire model 20b travels when a different second thermal conductivity is set in the recessed area 37 of the tire model 20b. FIG. 15 is a flowchart illustrating an example of a processing procedure of the second relational expression definition step S37.

  In the second relational expression defining step S37 of this embodiment, first, a plurality of elements for setting at least a part of the element F (i) of the recessed area 37 of the two-dimensional tire model 20b shown in FIGS. A different second thermal conductivity is determined (step S371). The second thermal conductivity can be appropriately set as long as it is higher than the first thermal conductivity. A plurality of second thermal conductivities are determined from the above range. The number of second thermal conductivities can be set as appropriate. For example, it is desirable that about 3 to 10 second thermal conductivities be set. These second thermal conductivities are stored in the computer 1.

  Next, in the second relational expression defining step S37 of this embodiment, one second thermal conductivity selected from the plurality of second thermal conductivities is the two-dimensional tire shown in FIGS. It is defined as at least a part of the element F (i) of the recessed area 37 of the model 20b (step S372). In step S372, as shown in FIG. 5, in the heat transfer coefficient defining step S2 (shown in FIG. 3), and in steps S31 and S32 (shown in FIG. 7) of the heat conductivity defining step S3, the heat transfer coefficient. A two-dimensional tire model 20b in which the thermal conductivity of the constituent members of the tire model 20b excluding the tread rubber 21a and the first thermal conductivity are defined is used. Then, as shown in FIG. 6, the second thermal conductivity is set only in the recessed region 37 (in this embodiment, the shoulder lateral groove region 37c) where the second thermal conductivity is scheduled. In this embodiment, the same first thermal conductivity as that of the non-recessed region 36 is defined in the center lateral groove region 37a and the middle lateral groove region 37b in which the second thermal conductivity is not set.

  Next, in the second relational expression defining step S37 of this embodiment, boundary conditions are defined for the tire model in the computer 1 (step S373). A state in which the three-dimensional tire model 20a rolls on the road surface model 38 is calculated based on the predetermined traveling speed Vs (step S374). These steps S373 and S374 are performed based on the same processing procedure as the steps S333 and S334 of the second thermal conductivity definition step S33 shown in FIG. The traveling speed Vs is set to a traveling speed (for example, 80 km / h) when the tire 2 is traveling.

  Next, in the second relational expression defining step S37 of this embodiment, the heat generation amount during traveling of the three-dimensional tire model 20a, the heat dissipation amount during traveling of the two-dimensional tire model 20b, and the two-dimensional tire model 20b. Is calculated (step S375). Step S375 is performed based on the same processing procedure as Step S335, Step S336, and Step S337 of the second thermal conductivity definition step S33 shown in FIG.

  Next, in the second relational expression defining step S37 of this embodiment, it is determined whether or not the temperature of each element F (i) of the two-dimensional tire model 20b has converged (step S376). This step S376 is performed based on the same processing procedure as step S338 of the second thermal conductivity definition step S33 shown in FIG.

  When it is determined in step S376 that the temperature of each element F (i) of the two-dimensional tire model 20b has converged (“Y” in step S376), each element F (i) of the two-dimensional tire model 20b Can be treated as the temperature when the tire is traveling (that is, when traveling at a preset traveling speed Vs). Thereby, 2nd relational expression definition process S37 can calculate the temperature of the two-dimensional tire model 20b based on the 2nd thermal conductivity set to the recessed part area | region 37 of the tire model 20b. Then, the next step S377 is performed.

  On the other hand, when it is determined in step S376 that the temperature of each element F (i) of the two-dimensional tire model 20b has not converged (“N” in step S376), each element of the two-dimensional tire model 20b The temperature of F (i) cannot be treated as the temperature during tire traveling (that is, when traveling at a preset traveling speed Vs). In this case, the temperature of each element F (i) of the two-dimensional tire model 20b (that is, the temperature of the element F (i) set in step S373) is the same as that of the two-dimensional tire model 20b calculated in step S375. The temperature of each element F (i) is updated (step S378). Further, the unit time T (x) is advanced by one (step S379), and steps S374 to S376 are performed again based on the temperature of each element F (i) of the updated two-dimensional tire model 20b. .

  Next, in the second relational expression defining step S37 of this embodiment, all the second thermal conductivities set in step S371 are defined in the element F (i) of the recessed region 37 of the two-dimensional tire model 20b. It is determined whether or not (step S377). In step S377, when it is determined that all the second thermal conductivities set in step S371 are defined (“Y” in step S377), the next step S380 is performed. On the other hand, when it is determined that all the second thermal conductivities set in step S371 are not defined (“N” in step S377), the other second thermal conductivities are two-dimensional tire models 20b. (Step S381), and steps S373 to S377 are performed again. Thus, in the second relational expression defining step S37, the temperature during travel of the two-dimensional tire model 20b is calculated for all the second thermal conductivities set in step S371.

  Next, in the second relational expression defining step S37, the second thermal conductivity defined in the recessed area 37 of the two-dimensional tire model 20b and the temperature of the evaluation target portion during traveling of the two-dimensional tire model 20b are calculated. A second relational expression indicating the relationship is obtained (step S380). In step S380 of this embodiment, first, the temperature of the evaluation target portion is acquired from the temperatures of the respective elements F (i) of the two-dimensional tire model 20b shown in FIG.

In step S380, an approximate curve is obtained by the least square method based on the temperature of the evaluation target portion during travel of the two-dimensional tire model 20b calculated for each of the plurality of second thermal conductivities. This approximate curve is a second relational expression between the second thermal conductivity set in the recessed region 37 of the two-dimensional tire model 20b and the temperature of the evaluation target portion during travel of the two-dimensional tire model 20b. The second relational expression is shown in the following expression (2). Such a second relational expression can uniquely determine the temperature of the evaluation target portion when the two-dimensional tire model 20b travels by substituting the second thermal conductivity λ. Such a second relational expression is input to the computer 1.
Tb = g (λ) (2)
here,
Tb: temperature of the evaluation target part during running of the tire model λ: second thermal conductivity

Next, in the second thermal conductivity defining step S33 of this embodiment, based on the first relational expression represented by the above formula (1) and the second relational formula represented by the above formula (2), the second A thermal conductivity and a relational expression of the volume ratio and surface area ratio of the recess 18 (in this embodiment, the lateral groove 13B) (hereinafter sometimes simply referred to as “third relational expression”) are defined (third relation). Formula definition step S38). In the third relational expression defining step S38, it is assumed that the temperature Ta of the evaluation target portion of the tire of the first relational expression is the same as the temperature Tb of the evaluation target part during travel of the tire model of the second relational expression ( That is, f (x1, x2,...) = G (λ)) and the third relational expression are obtained. The third relational expression is shown in the following expression (3). Such a third relational expression can uniquely determine the second thermal conductivity λ by substituting the volume ratio x1 and the surface area ratio x2 of the recess 18 (in this embodiment, the lateral groove 13B). Such a third relational expression is input to the computer 1.
λ = h (x1, x2) (3)
here,
λ: second thermal conductivity x1: volume ratio of the recess x2: surface area ratio of the recess

  Next, in the second thermal conductivity defining step S33 of this embodiment, the second thermal conductivity is determined based on the third relational expression represented by the above formula (3) (step S39). As described above, the third relational expression indicates the relationship between the second thermal conductivity and the volume ratio and the surface area ratio of the recess 18 (in the present embodiment, the lateral groove 13B). The second thermal conductivity is uniquely obtained by substituting the volume ratio and the surface area ratio of the lateral groove 13B into the third relational expression. As a result, the volume ratio and surface area ratio of the recess 18 (the heat release factor of the lateral groove 13B (in this embodiment, the groove width and the number of pitches)) are not specifically defined in the tire model (for example, the lateral groove is modeled). In addition, the heat dissipation amount of the tire model 20b having various heat dissipation factors can be easily calculated based on the second thermal conductivity obtained by the third relational expression. Therefore, by setting such second thermal conductivity in the recessed region 37, it is possible to accurately predict the evaluation target portion of the tire model 20b having various heat dissipation factors.

  In the embodiments so far, the thermal conductivity is defined for each element F (i) of the two-dimensional tire model 20b. However, the present invention is not limited to such a mode. For example, the above-described thermal conductivity may be defined for each element F (i) of the three-dimensional tire model 20a shown in FIG. FIG. 16 is a perspective view of a portion of a tread rubber 21a of a three-dimensional tire model 20a according to another embodiment of the present invention. In FIG. 16, the element F (i) shown in FIG. 6 is omitted. Further, in this embodiment, the same components as those in the previous embodiments are denoted by the same reference numerals, and description thereof may be omitted.

  In the second thermal conductivity definition step S33, a region 41 continuous in the tire circumferential direction including the length in the tire axial direction of the recessed region 37 in the rubber portion 21 (the tread rubber 21a in the present embodiment) of the tire model 20a. In addition, a second thermal conductivity may be defined. In this case, the first thermal conductivity is defined in the region 42 including the non-recessed region 36 and continuing in the tire circumferential direction. Even if such a three-dimensional tire model 20a does not have a lateral groove, temperature calculation in consideration of the heat dissipation of the lateral groove 13B of the tire 2 shown in FIG. 2 is possible. Moreover, in such a simulation method using the tire model 20a, the physical quantity related to the temperature of the tire model 20a can be calculated without setting the two-dimensional tire model 20b. Can be shortened.

  In this embodiment, the case where the second thermal conductivity is defined in the region 41 of the three-dimensional tire model 20a is exemplified, but the present invention is not limited to such a mode. FIG. 17 is a partial perspective view of a tread rubber 21a of a three-dimensional tire model 20a according to still another embodiment of the present invention. In FIG. 17, the element F (i) shown in FIG. 6 is omitted. Further, in this embodiment, the same components as those in the previous embodiments are denoted by the same reference numerals, and description thereof may be omitted.

  In this embodiment, in the three-dimensional tire model 20a, the second thermal conductivity may be defined in the lateral groove forming region 45 where the lateral groove 13B of the tire 2 is formed. The transverse groove forming region 45 is an element F that overlaps with the transverse groove obtained from the design data (for example, CAD data) of the vulcanization mold among the elements F (i) constituting the tread rubber 21a of the three-dimensional tire model 20a. Defined in (i). Such a three-dimensional tire model 20a can be calculated in accordance with the shape of the lateral groove 13B and taking into account the heat dissipation of the lateral groove 13B without being divided according to the shape of the lateral groove of the tire 2. Therefore, the three-dimensional tire model 20a of this embodiment can perform temperature calculation of the tire 2 with higher accuracy.

  In the embodiment so far, the center land portion 32a, the middle land portion 32b, and the shoulder land portion 32c of the tire model 20b are provided with the recessed region 37 (shown in FIG. 16) or the lateral groove forming region 45 in which the second thermal conductivity is defined. Although the aspect which sets (shown in FIG. 17) and the physical quantity regarding the temperature of a tire was calculated was illustrated, it is not limited to such an aspect. For example, even in a tire model (not shown) in which a tire (not shown) in which only the lateral groove 14 (for example, lug groove) is provided on the tread rubber 11a not provided with the main groove 13A is modeled, the recessed region 37 ( The physical quantity related to the temperature of the tire can be calculated. In this case, by setting the region that was the lug groove portion of the tread rubber of the tire model as the recessed region 37, it is possible to calculate the temperature in consideration of the heat radiation of the lug groove.

  In the simulation methods of the embodiments so far, the dynamic analysis in which the heat generation amount is calculated by rolling the three-dimensional tire model 20a to the road surface model 38 is exemplified, but the present invention is not limited to this. For example, static analysis may be used to calculate the amount of heat generated when the tire model 20a travels without rolling the three-dimensional tire model 20a on the road surface model 38. In this case, it is desirable that the amount of heat generated when the tire model 20a travels is calculated based on the amount of strain variation in the tire circumferential direction of the tire model 20a. Such a static analysis can shorten the calculation time compared to the dynamic analysis. Such a calorific value can be easily calculated by using, for example, analysis application software (ABAQUS manufactured by Dassault Systems, etc.).

  In the simulation methods of the embodiments described so far, the case where the concave portion 18 in which the concave region 37 is set is the lateral groove 14 provided in the tread rubber 11a is exemplified, but the present invention is not limited to such a mode. . The recess 18 may be, for example, a lateral groove (not shown) extending from the tread rubber 11a to the sidewall rubber 11b, a dimple (not shown) recessed from the sidewall rubber 11b, or the main groove 13A. Thereby, even if these recessed parts 18 are not set in the rubber part of tire model 20a, 20b, the physical quantity relevant to the temperature of tire model 20a, 20b can be calculated in consideration of the heat radiation in recessed part 18. .

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

[Example A]
The tire shown in FIG. 2 was manufactured, and the temperature of the evaluation target portion (for example, the shoulder land portion) was actually measured under the following travel conditions (travel speed, tire internal pressure, load) (experimental example). An infrared thermography manufactured by FLIR SYSTEMS was used for measuring the temperature of the evaluation target portion. As a result of the measurement, the temperature of the evaluation target portion was 108 ° C.

  A tire model obtained by modeling the tire shown in FIG. 2 was set in the computer in accordance with the processing procedure shown in FIGS. 3 and 7 (Examples 1 to 6 and Comparative Example). In Examples 1 to 6 and the comparative example, a tire model obtained by modeling a tire in a state where the concave portion (lateral groove) is filled is input. In Examples 1 to 6, the first thermal conductivity based on the thermal conductivity of the tire tread rubber was set in the non-recessed region element of the tire model tread rubber according to the processing procedure shown in FIG. . Furthermore, in Examples 1-6, the 2nd heat conductivity shown in Table 1 was set to the element of the recessed part area | region which was a recessed part (lateral groove). On the other hand, in the comparative example, the first thermal conductivity was set for the elements of the non-recessed area and the recessed area.

In Examples 1-6, time until a tire model was created was measured. Further, according to the processing procedure shown in FIG. 9, physical quantities (temperature of the evaluation target portion) related to the temperatures of the tire models of Examples 1 to 6 and the comparative example are calculated, and a difference from the temperature of the evaluation target portion of the tire is calculated. It was. This shows that the smaller the absolute value of the temperature difference, the more accurately the physical quantity related to the temperature of the tire model can be calculated in consideration of the heat dissipation of the recess (lateral groove). The common specifications are as follows. The test results are shown in Table 1.
Tire size: 11R22.5
Rim size: 7.5 × 22.5
Tire internal pressure: 700kPa
Load: 31.81kN
Travel speed: 80km / h

  As a result of the test, the creation time of the tire models of Examples 1 to 6 was 40% of the conventional creation time for subdividing the lateral grooves. Therefore, the creation methods of Examples 1 to 6 were able to shorten the creation time of the tire model as compared with the conventional creation method. Furthermore, the tire models created in Examples 1 to 6 were able to approximate the temperature of the evaluation target portion of the tire of Experimental Example 1 as compared with the tire models created in the comparative example. Therefore, even if the tire model created in Examples 1 to 6 does not have a lateral groove in the tire model, it is possible to accurately calculate the physical quantity related to the temperature of the tire model in consideration of the heat dissipation of the lateral groove. did it.

[Example B]
A tire having the basic structure shown in FIG. 2 and having a lateral groove with a depth (50%, 75%, and 100%) of the lateral groove with respect to a reference depth of 24 mm was manufactured (Experimental Example 2). And in the said driving conditions (tire internal pressure, load), the temperature of the evaluation object part was measured for every driving speed (70 km / h, 80 km / h, and 90 km / h). The same method as in Example A is used as the method for measuring the temperature of the part to be evaluated.

  A tire model obtained by modeling the tire shown in FIG. 2 was set in the computer according to the processing procedure shown in FIGS. 3, 7 and 8 (Example 7). In the second thermal conductivity defining step of the seventh embodiment, based on the processing procedure shown in FIG. 12 and the temperature of the evaluation target portion of the tire actually traveled according to the travel conditions (travel speed, tire internal pressure, load). Thus, the second thermal conductivity was determined. The ratio of the second thermal conductivity defined in this process to the first thermal conductivity (second thermal conductivity / first thermal conductivity) was 2.5.

  According to the second thermal conductivity obtained in the above processing procedure and the processing procedure shown in FIG. 9, the physical quantity related to the temperature of the tire model of Example 7 (temperature of the evaluation target portion) is the traveling speed (70 km / h, Calculated every 80 km / h and 90 km / h). And the relationship between the temperature of the evaluation object part at the time of driving | running | working of the tire model of Example 7 and the temperature of the evaluation object part at the time of driving | running | working of the tire was calculated | required for every driving speed.

  FIG. 18 shows the relationship between the temperature of the evaluation target portion when the tire of Experimental Example 2 is traveling (70 km / h) and the temperature of the evaluation target portion when the tire model of Example 7 is traveling (70 km / h). It is a graph. FIG. 19 shows the relationship between the temperature of the evaluation target portion when the tire of Experimental Example 2 is traveling (80 km / h) and the temperature of the evaluation target portion when the tire model of Example 7 is traveling (80 km / h). It is a graph. FIG. 20 shows the relationship between the temperature of the evaluation target portion when the tire of Experimental Example 2 is traveling (90 km / h) and the temperature of the evaluation target portion when the tire model of Example 7 is traveling (90 km / h). It is a graph.

  As a result of the test, in Example 7, the temperature of the evaluation target portion during traveling of the tire model is set to the temperature of the evaluation target portion during traveling of the tire of Experimental Example 2 under the conditions where the traveling speed and the depth of the lateral groove are different. It was within ± 5 ° C. Therefore, the production method of Example 7 in which the second thermal conductivity was determined was able to accurately calculate the physical quantity related to the temperature of the tire model in consideration of the heat dissipation of the lateral grooves even under different conditions. .

[Example C]
Two tires having the basic structure shown in FIG. 2 and having different heat release factors for the lateral grooves 13B (in this example, the groove width and the number of pitches of the lateral grooves) were produced (Experimental Example 3). And in the said driving conditions (tire internal pressure, load), the temperature of the evaluation object part was measured for every driving speed (70 km / h, 80 km / h, and 90 km / h). The same method as in Example A was used as the method for measuring the temperature of the part to be evaluated.

  A third relational expression between the second thermal conductivity, the volume ratio of the lateral groove and the surface area ratio was determined according to the processing procedure shown in FIG. 13 (Example 8). In Example 8, ten tires having a heat release factor different from that of the tire of Experimental Example 3 are manufactured according to the processing procedure shown in FIG. 14, and the volume ratio and surface area ratio of the lateral grooves and the temperature of the evaluation target portion of the tire are obtained. The first relational expression showing the relationship with is defined. In Example 8, the second heat conductivity set in the recessed area of the tire model and the temperature of the evaluation target portion during the running of the two-dimensional tire model according to the processing procedure shown in FIG. A relational expression has been defined. Furthermore, in Example 8, the third relational expression was obtained based on the first relational expression and the second relational expression.

  In Example 8, the volume ratio and the surface area ratio of each tire of Experimental Example 3 were substituted into the third relational expression, and five second heat transfer coefficients were determined. And according to these 2nd heat conductivity and the process sequence shown in FIG. 9, the physical quantity (temperature of evaluation object part) regarding the temperature of the tire model of Example 8 is driving speed (70 km / h, 80 km / h). And every 90 km / h). And the relationship between the temperature of the evaluation object part at the time of driving | running | working of the tire of Experimental example 3 and the temperature of the evaluation object part at the time of driving | running | working of the tire model of Example 8 was calculated | required for every driving speed.

  FIG. 21 shows the relationship between the temperature of the evaluation target portion when the tire of Experimental Example 3 is traveling (70 km / h) and the temperature of the evaluation target portion when the tire model of Example 8 is traveling (70 km / h). It is a graph. FIG. 22 shows the relationship between the temperature of the evaluation target portion when the tire of Experimental Example 3 is traveling (80 km / h) and the temperature of the evaluation target portion when the tire model of Example 8 is traveling (80 km / h). It is a graph. FIG. 23 shows the relationship between the temperature of the evaluation target portion when the tire of Experimental Example 3 is traveling (90 km / h) and the temperature of the evaluation target portion when the tire model of Example 8 is traveling (90 km / h). It is a graph.

  As a result of the test, in Example 8, the temperature of the evaluation target portion during running of the tire model was tested under different conditions of the heat release factor of the horizontal groove (in this example, the groove width and the number of pitches of the horizontal groove) and the running speed. It was able to be kept within ± 5 ° C. of the temperature of the portion to be evaluated during running of the example tire. Therefore, the production method of Example 8 was able to accurately calculate the physical quantity related to the temperature of the tire model in consideration of the heat dissipation of the lateral grooves even under conditions where the heat dissipation factors of the lateral grooves were different.

S1 Tire model input process S3 Thermal conductivity definition process

Claims (4)

A method for creating a tire model for numerical analysis of a tire provided with a recess recessed from a rubber portion including tread rubber using a computer,
Inputting to the computer a tire model obtained by modeling the tire in a state where the recess is filled with a finite number of elements;
The computer includes a thermal conductivity defining step for defining a thermal conductivity for each element of the tire model,
The thermal conductivity defining step includes a step of defining a first thermal conductivity in the non-recessed region element that is a portion other than the recessed portion in the rubber portion of the tire model;
And defining a second thermal conductivity larger than the first thermal conductivity in at least a part of the element in the recessed area that is the recessed portion of the rubber portion of the tire model. How to create a tire model.   The tire model creation method according to claim 1, wherein the tire model is a two-dimensional model having a meridian cross section including a tire rotation axis.   The tire model is a three-dimensional model, and the second thermal conductivity is defined in a region continuous in a tire circumferential direction including a length in a tire axial direction of the recessed portion in the rubber portion of the tire model. The method for creating a tire model according to claim 1.   Using the tire model created by the method according to any one of claims 1 to 3, the computer calculates a physical quantity related to the temperature of the tire model based on a predetermined condition and the thermal conductivity. A tire temperature simulation method comprising a calculation step.