JP6000893B2 - Calculation method of tire snow and snow performance value, tire snow and snow performance value calculation device, and computer program - Google Patents

Description

  The present invention relates to a tire snow / snow performance value calculation method for calculating a snow / snow performance value for a tire, a tire snow / snow performance value calculation apparatus, and a computer program.

  In tires such as studless tires used in scenes that run on icy and snowy roads, cuts called sipe are formed on the treads of the land (blocks or ribs). Performance is enhanced.

  It is conceivable to use computer simulation in the tire design field in order to derive the sipe shape and sipe arrangement that can provide appropriate snow and snow performance. For example, Patent Document 1 discloses one method for evaluating the snow and snow performance of a tire. The method of Patent Document 1 generates a block model in which a tread block having a sipe is modeled by a plurality of elements, performs an analysis for grounding and shearing the block model by a finite element method or the like, and calculates a ground pressure generated in the sipe. calculate. In addition, the projection length corresponding to the sliding direction of the sipe is calculated, and the index value of the ice / snow performance is calculated by integrating the projection length and the contact pressure.

JP 2011-201390 A

  However, the method of Patent Document 1 calculates the evaluation value of the snow / snow performance of only one block, and therefore cannot calculate the snow / snow performance value in consideration of the tire structure such as the internal structure. Further, in the conventional method, since a model having only blocks is used, the arrangement position of the sipe in the tire is not taken into consideration.

  Furthermore, in the above method, since a block including a sipe shape is modeled, when trying to evaluate by changing the arrangement and inclination of the sipe, the model must be recreated and the analysis by the finite element method must be sequentially performed. The man-hour for generating or correcting the model and the time required for the analysis become enormous.

  The present invention has been made paying attention to such problems, and its purpose is to avoid the increase in man-hours and calculation cost, and to calculate the snow and snow performance value that can calculate the snow and snow performance value in consideration of the tire structure. Calculation method, tire snow and snow performance value calculation device, and computer program.

  In order to achieve the above object, the present invention takes the following measures.

  That is, the tire snow and snow performance value calculation method of the present invention performs a ground contact analysis by a finite element method under a predetermined load using a tire model obtained by modeling a tire having no sipe formed on a tread with a plurality of elements, The step of calculating the contact surface shape and the contact pressure for each element constituting the contact surface, and the weighting factor corresponding to the cumulative value of the contact pressure of all the elements on a certain position in the tire width direction based on the contact analysis result And calculating a plurality of pixels having edge effects according to a predetermined sliding direction from a step of calculating a plurality of different positions in the width direction and a sipe image to be evaluated with the arrangement position and orientation set with respect to the tread surface And identifying the weighting coefficient corresponding to the position in the tire width direction of the pixel for each extracted pixel, accumulating the identified weighting coefficient, and using the accumulated value as an index value for ice / snow performance Has a step, a.

  The tire snow / snow performance value calculation device of the present invention performs a grounding analysis by a finite element method under a predetermined load using a tire model in which a tire having no sipe formed on a tread is modeled by a plurality of elements, Based on the calculation result of the contact pressure calculation unit and the contact pressure calculation unit for calculating the contact pressure for each element constituting the shape and the contact surface, the total of the contact pressures of all the elements on a certain position in the tire width direction A weighting factor calculation unit that calculates a plurality of weighting factors corresponding to values in different width direction positions, and a sipe image that is an evaluation target in which an arrangement position and orientation are set with respect to the tread surface, according to a predetermined sliding direction An extraction unit for extracting pixels of a part having an edge effect, and for each pixel extracted by the extraction unit, the weighting factor corresponding to the position in the tire width direction of the pixel is specified, and the specified weighting factor is accumulated and accumulated value Comprising the index value calculating section as an index value of ice and snow performance, the.

  In this way, the ground analysis by the finite element method is only required once, the edge image is extracted from the sipe image to be evaluated, the weight coefficient is specified, and the weight coefficient is accumulated. Even if the arrangement position and orientation are changed, the ground contact analysis by the finite element method is not required again, and it is not necessary to recreate the tire model. Therefore, the calculation cost and the man-hour can be significantly reduced. Nevertheless, since the weighting coefficient corresponding to the position in the width direction of the sipe pixel is specified, the ice / snow performance value (index value) considering the sipe position can be calculated, and the prediction accuracy can be improved.

  In order to easily calculate the weighting factor, the weighting factor at a certain position in the width direction is obtained by calculating the contact pressure at the certain position in the width direction on the line along the width direction passing through the base point set on the contact surface, and The cumulative value of the contact pressure of the line along the front-rear direction passing through the base point when the pressure value at the base point is a reference value, and the contact length at the position in the certain width direction when a certain length is the reference length It is preferable to calculate by integrating.

  In order to enable user-friendly analysis, it is preferable to calculate the weighting coefficient corresponding to the position of the extracted pixel in the tire width direction by interpolating the weighting coefficient at a plurality of locations in the tire width direction.

  In the present invention, the steps constituting the above method can be specified from the viewpoint of a program.

That is, the computer program of the present invention performs a grounding analysis by a finite element method under a predetermined load using a tire model obtained by modeling a tire having no sipe formed on a tread with a plurality of elements, and forms a grounding surface shape and a contact surface. The step of calculating the contact pressure for each element constituting the ground and the weighting coefficient corresponding to the cumulative value of the contact pressures of all the elements on a certain position in the tire width direction based on the contact analysis result, A plurality of calculation steps, a step of extracting a pixel of a part having an edge effect according to a predetermined sliding direction from a sipe image to be evaluated with an arrangement position and orientation set with respect to the tread surface, and extraction The weight coefficient corresponding to the position of the pixel in the tire width direction is identified for each pixel, the accumulated weight coefficient is accumulated, and the accumulated value is used as an index value for ice / snow performance. To be executed and up, to the computer.
By executing this program, the operational effects produced by the above method can be obtained.

The block diagram which shows typically the calculation apparatus of the tire snow and snow performance value which concerns on this invention. The top view which shows typically the sipe arrange | positioned at a land part (a block and a rib). The top view which shows typically the sipe arrange | positioned at a land part (a block and a rib). The figure which shows a grounding analysis result. The perspective view which shows the grounding pressure of a grounding surface typically by height. The figure which shows the contact pressure distribution of the width direction in the base point of FIG. 4A. The figure which shows the contact pressure distribution of the front-back direction in the base point of FIG. 4A. The figure which shows the contact length distribution in FIG. 4A. The figure which shows the relationship between the width direction position and a weighting coefficient. Explanatory drawing which shows a sipe image. FIG. 6B is an explanatory diagram illustrating a state in which pixels of a part that exhibits the edge effect are extracted from the sipe image of FIG. The flowchart which shows the method of calculating a tire snow and snow performance value. The figure which shows the calculation result of a tire snow and snow performance value. The figure which shows the calculation result of a tire snow and snow performance value.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[Calculation device for tire snow / ice performance value]
The tire snow / snow performance value calculation device 2 according to the present embodiment calculates the snow / snow performance value (index value) of the sipe to be evaluated in consideration of the arrangement position, direction (angle), and tire structure with respect to the tire tread. It is. As shown in FIGS. 2A and 2B, the sipe 12 can be expressed by a shape on the tread surface, and various shapes are conceivable. The sipe 12 is arrange | positioned at the land part (block 10 or rib 11) divided by the main groove 1 extended in tire circumferential direction CD. The land portion on the center C side in the tire width direction WD is referred to as a center land portion Ce, and the land portion at the end portion in the tire width direction WD is referred to as a shoulder land portion Sh. Depending on the number of main grooves 1, there may be a mediate land portion Me between the center land portion Ce and the shoulder land portion Sh. The arrangement position and orientation of the sipe 12 can be changed as design values. The sipe 12 is arranged in any one of the shoulder land portion Sh, the mediate land portion Me, and the center land portion Ce according to the arrangement position. The sipe 12 shown in FIG. 2A is an example of a wave-shaped sipe, and the sipe 12 shown in FIG. 2B is an example of a rectangular sipe.

  Specifically, as shown in FIG. 1, the tire snow and snow performance value calculation device 2 includes an initial setting unit 20, a contact pressure calculation unit 21, a weight coefficient calculation unit 22, an extraction unit 23, and an index value calculation unit. 24. These units 20 to 24 are realized by cooperation of software and hardware by executing a processing routine (not shown) stored in advance by the CPU in an information processing apparatus such as a personal computer having a CPU, a memory, various interfaces, and the like. Is done.

  The initial setting unit 20 shown in FIG. 1 accepts an operation from a user via a known operation unit such as a keyboard or a mouse, sets a tire model in which a tire is modeled by a plurality of elements, a load value applied to the tire model, and Various settings necessary for ground pressure analysis using a finite element method such as an internal pressure value are executed, and these setting values are stored in a memory (not shown). Further, the initial setting unit 20 accepts the data (vector data, image data, etc.) of the sipe 12 to be evaluated shown in FIGS. 2A and 2B, and the settings related to the sipe arrangement position and its orientation, and stores them in the memory. In this embodiment, a tire model having a land portion including a block or a rib and including an internal structure from a tread portion to a bead portion is used as a tire model, but a tire model having no sipe formed on a tread surface is used. . Sipe means a groove having a groove width of 1.5 mm or less. The direction in which the load is applied is set only in the vertical direction to simplify the calculation.

  The ground contact pressure calculation unit 21 shown in FIG. 1 performs a ground contact analysis by a finite element method using a tire model under analysis conditions including a preset tire model, a predetermined load, and a predetermined internal pressure. The ground pressure for each element constituting the ground is calculated.

FIG. 3 is a diagram illustrating a calculation result of the contact pressure calculation unit 21. As shown in FIG. 3, as a result of the grounding analysis, the grounding pressure is obtained for each of the elements constituting the grounding surface shape and the grounding surface. In FIG. 3, the contact pressure is indicated by a color in the drawing, and elements are represented by stitch-like lines. For convenience of explanation, the tire width direction WD is assumed to be the x coordinate, and the tire longitudinal direction CD (tire circumferential direction) is assumed to be the y coordinate. As shown in the figure, the data of the ground contact analysis result is a three-dimensional structure composed of coordinates (xy) in the tire width direction WD and tire longitudinal direction CD (tire circumferential direction) and the ground pressure P _xy at the coordinates (xy). It becomes data. On the other hand, the sipe shape is two-dimensional data composed of coordinates (xy) in the tire width direction WD and the tire longitudinal direction CD, as shown in FIGS. 2A and 2B. Since the edge effect (ice / snow performance value) of the sipe changes according to the contact pressure, it is necessary to refer to both the ground analysis result data and the sipe shape data in order to appropriately calculate the sipe ice / snow performance value.

Therefore, the weighting factor calculation unit 22 shown in FIG. 1 uses the ground analysis result data, which is three-dimensional data, as the coordinate x in the tire width direction WD and the coordinate x to enable association with the sipe data of the two-dimensional data. Is converted to two-dimensional data (see FIG. 5) composed of the weighting coefficient wc (x). Weighting factor wc, as shown in FIG. 3, is a value corresponding to the cumulative value of the contact pressure _P of all the elements located on a certain position _{X 1} in the tire width direction _{WD (X1, j = 1~N1)} . N1 denotes the number of elements in the coordinate X ₁ of the elements constituting the ground plane. The weighting factor calculation unit 22 shown in FIG. 1 calculates a plurality of weighting factors wc (x) by changing the width direction position x based on the contact analysis result of the contact pressure calculation unit 21. In the present embodiment, the number of element rows in the tire width direction WD constituting the contact surface and the weight coefficient wc (x) are calculated.

Weighting coefficients wc (x) is a value corresponding to the cumulative value of the contact pressure _P of all the elements located on a certain position _{X 1} in the tire width direction _{WD (X1, j = 1~N1)} , present In the embodiment, the following processing is performed in order to give a degree of freedom to the elements of the tire model and to facilitate the calculation of the weighting coefficient wc.

FIG. 4A is a diagram schematically showing the ground contact surface Ch and the contact pressure of the contact surface in terms of height. Specifically, as shown in FIG. 4, the weighting factor wc (x ₁ ) at a certain width direction position x ₁ is a line along the width direction WD passing through the base point S 1 by setting the base point S 1 on the ground plane Ch. contact pressure P of a certain position in the width direction _{x 1} on the L1 and _{(x 1),} the reference value the pressure value _{P S1} of the base point S1 (1) and to the line L2 along the longitudinal direction CD through the base point S1 of if Accumulating the cumulative value PL in the front-rear direction of the contact pressure and the contact length CL (x ₁ ) at a certain width direction position x ₁ when a certain length is set as a reference length (1 in the present embodiment). Calculate with In the present embodiment, the center of the ground plane Ch is set as the base point S1. FIG. 4B shows a contact pressure distribution PW (see FIG. 4A) on the line L1 along the width direction WD passing through the base point S1. The contact pressure P (x ₁ ) at a certain width direction position x ₁ is as shown in the figure. FIG. 4C shows the contact pressure distribution PL (see FIG. 4A) of the line L2 along the front-rear direction CD passing through the base point S1. Pressure value _{P S1} of the base point S1 is is shown in FIG. FIG. 4D shows a contact length distribution CL when the circumferential length Pt of the minimum unit when the sipes shown in FIGS. 2A and 2B are repeatedly arranged is the reference length (1).

  Further, as shown in FIG. 5, the weighting coefficient wc becomes discrete data due to the finite element analysis as indicated by a cross in the drawing. Therefore, as shown in the figure, the weighting factor calculation unit 22 interpolates the weighting factors at a plurality of locations (locations indicated by crosses) in the tire width direction WD by interpolation processing such as splines (in the figure, continuous data). (Shown as a continuous line).

FIG. 6A is a diagram illustrating a sipe image. The number is a pixel indicating sipes.
As shown in FIG. 6A, the extraction unit 23 shown in FIG. 1 corresponds to a predetermined sliding direction (front-rear direction CD in the present embodiment) from a sipe image to be evaluated with the arrangement position and orientation set with respect to the tread. Extract a pixel of a part having an edge effect. As shown in FIG. 6A, when a plurality of sipe pixels are consecutive in a predetermined sliding direction (front-rear direction CD) as a pixel having an edge effect corresponding to a predetermined sliding direction, the first pixel (the pixel indicated by numeral 1) ). The pixel indicated by the numeral 2 is a pixel that is continuous with the first pixel (indicated by the numeral 1). Specifically, vector data such as CAD is often used for designing a sipe pattern, and the sipe pattern is appropriately rotated in the vector data so as to have a predetermined orientation. Next, the vector data is converted into pixel data (pixel data). Then, as shown in FIG. 6A, in the pixel data, there are cases where pixels indicating sipes are gathered according to the thickness or inclination angle of sipes. In this case, the pixel having the edge effect is considered to be only the leading pixel in the predetermined sliding direction, and only the leading pixel is extracted as shown in FIG. 6B.

  The index value calculation unit 24 illustrated in FIG. 1 specifies the weighting factor wc (x) corresponding to the position x in the tire width direction of each pixel (see FIG. 6B) extracted by the extraction unit 23, and specifies the specified weight. The coefficient wc (x) is accumulated, and the accumulated value is used as an index value for ice / snow performance. Here, if the index value is calculated only for one sipe pattern, the ice / snow performance value can be calculated for each sipe, and if the index value is calculated for all the sipe patterns arranged in the tire, Snow and snow performance values can be calculated.

[Calculation method of tire snow and snow performance value]
A method of calculating the tire snow performance value using the calculation device 2 will be described with reference mainly to the flowchart of FIG.

  First, in step ST1, the initial setting unit 20 shown in FIG. 1 receives a user's operation via an operation unit (not shown), a tire model, a load value, sipe image data to be evaluated and its arrangement position, Make various settings such as orientation.

  In the next step ST2, the contact pressure calculation unit 21 shown in FIG. 1 performs a contact analysis by a finite element method under a predetermined load using a tire model obtained by modeling a tire having no sipe formed on a tread with a plurality of elements. As shown in FIG. 3, the contact surface shape and the contact pressure for each element constituting the contact surface are calculated.

In the next step ST3, the weighting factor calculation unit 22 shown in FIG. 1, based on the calculation result of the ground pressure calculation section 21, contact pressure P of all the elements located on a certain position X ₁ in the tire width direction WD _{(X1 , J = 1 to N1)} , a plurality of weighting factors wc (x) corresponding to the total values of the width direction position x are calculated. Specifically, the weighting factor calculation unit 22, as shown in FIG. 4A-D, the width direction through a weight factor wc _{(x 1)} at a certain position in the width direction _{x 1,} the base point S1, is set to the ground plane Ch ground pressure of one widthwise position _{x 1} on the line L1 along the WD P and _{(x 1),} along the longitudinal direction CD through the base point S1 in the case where the pressure value _{P S1} of the base point S1 as a reference value 1 calculated by accumulating the cumulative value PL of the ground contact pressure of the line L2, and a contact length of a given widthwise position x ₁ in the case of a certain length as the reference length CL (x _1).

  In the next step ST4, the weighting factor calculation unit 22 shown in FIG. 1 interpolates weighting factors wc (x) at a plurality of locations in the tire width direction WD and converts them into continuous data as shown in FIG.

  In the next step ST5, the CPU rotates the vector image data according to the set sipe direction and converts it into pixel data. In the next step ST6, the extraction unit 23 shown in FIG. 1 has an edge effect corresponding to a predetermined sliding direction as shown in FIG. 6B from the sipe image in which the arrangement position and orientation are set with respect to the road surface shown in FIG. 6A. The pixel of the part (pixel represented by numeral 1) is extracted.

  In the next step ST7, the index value calculation unit 24 shown in FIG. 1 specifies the weighting factor wc corresponding to the tire width direction position x of the pixel for each extracted pixel, and accumulates the weighting factor specified in step ST8. The cumulative value is used as an index value for ice / snow performance.

  The example which implemented the said calculation apparatus 2 and the calculation method is shown below.

In the example shown in FIG. 8, a tire model in which a block and a rib are arranged on a tread with a tire size of 140 / 70R14, but a tire on which a sipe is not arranged is modeled by a plurality of elements is used. The air pressure (internal pressure) was set to 200 kPa, the vertical load was set to 230 kgf, and ground contact analysis was performed by the finite element method. Then, the two patterns of sipe shown in FIG. 8 were set to the angle (orientation) shown in the figure and arranged in the mediate land portion Me, and the cumulative value of the weight coefficient was calculated. As shown in the graph in the figure, it can be seen that the performance of the rectangular sipe is improved every time the direction is inclined. It is presumed that the part that did not exhibit the edge effect when the inclination angle is 0 degrees gradually exhibits the edge effect. On the other hand, the performance of the wavy sipe did not change even when the direction was inclined. This is considered that the part which exhibits the edge effect newly and the part which loses the edge effect are almost equal.
As described above, the above-described consideration can be performed only by performing the ground contact analysis by the finite element method once, and the calculation cost and the man-hour for generating the tire model can be significantly reduced.

In the example shown in FIG. 9, the wavy sipe shown in the figure is placed in the center land portion Ce, the mediate land portion Me, and the shoulder land portion Sh, and the difference in performance due to the difference in the sipe placement position is calculated. Further, the difference in performance was calculated by varying the tire load. The load 1 is 230 kgf and the load 2 is 160 kgf. In any case, the sipe performance arranged in the center land portion Ce is set to 100, and other sipe is indicated by an index. As shown in FIG. 9, it can be seen that there is a difference in ice / snow performance depending on the tire width direction position x, that is, the land portion to be arranged.
Such consideration can be performed only by performing the ground contact analysis twice by the finite element method, and the calculation cost and the man-hour for generating the tire model can be significantly reduced.

As described above, the calculation method of the tire snow / snow performance value according to the present embodiment uses the tire model in which the tire having no sipe 12 formed on the tread is modeled by a plurality of elements, and uses the finite element method for grounding under a predetermined load conducted an analysis, and the step (ST2) for calculating the contact pressure for each element constituting a ground plane shape and a ground plane, on the basis of the ground analysis results, all the elements located on a certain position X ₁ in the tire width direction WD A step (ST3) of calculating a plurality of weighting coefficients wc (x) corresponding to the cumulative value P _{(X1, j = 1 to N1)} of the ground contact pressure by varying the width direction position x, and an arrangement position with respect to the tread surface And a step (ST6) of extracting a pixel of a part having an edge effect according to a predetermined slip direction from a sipe image to be evaluated with the orientation set, and corresponding to the tire width direction position x of each pixel extracted Identify the weighting coefficients wc (x) that has a step (ST7~8) as an index value of performance on ice and snow accumulated value by accumulating a specific weighting factors wc (x).

The tire snow and snow performance value calculation device 2 according to the present embodiment performs a grounding analysis by a finite element method under a predetermined load using a tire model obtained by modeling a tire having no sipe 12 formed on a tread with a plurality of elements. , and the ground pressure calculator 21 for calculating the contact pressure for each element constituting a ground plane shape and a ground plane, based on the calculation result of the ground pressure calculation unit 21, all located on a certain position X ₁ in the tire width direction WD A weighting factor calculation unit 22 for calculating a plurality of weighting factors wc (x) corresponding to the cumulative values of the contact pressures _{(X1, j = 1 to N1)} of the elements with different width direction positions x, and a tread surface An extraction unit 23 that extracts a pixel of a part having an edge effect corresponding to a predetermined slip direction from a sipe image to be evaluated with the arrangement position and orientation set, and a tire width direction of the pixel for each pixel extracted by the extraction unit 23 Corresponds to position x And an index value calculation unit 24 that identifies the weighting factor wc (x) to be used, accumulates the identified weighting factor wc (x), and uses the accumulated value as an index value of the ice / snow performance.

  According to this apparatus and method, the ground analysis by the finite element method is only required once, and it becomes an evaluation target because it is only necessary to extract the edge image from the sipe image to be evaluated, specify the weighting factor, and accumulate the weighting factor. Even if the position and direction of the sipe are changed, the ground contact analysis by the finite element method is not required again, and it is not necessary to recreate the tire model. Therefore, the calculation cost and the man-hour can be significantly reduced. Nevertheless, since the weighting coefficient wc (x) corresponding to the position x in the width direction of the sipe pixel is specified, the ice / snow performance value (index value) considering the sipe position can be calculated, and the prediction accuracy can be improved. .

Furthermore, in the present embodiment, the weighting coefficients wc (x ₁₎ at a certain position in the width direction x ₁ is one widthwise position x on the line L1 along the width direction WD through the base point S1, is set to the ground plane Ch _1, a ground pressure P (x ₁ ), a cumulative value PL of the ground pressure of the line L2 along the front-rear direction CD passing through the base point S1 when the pressure value P _S1 of the base point S1 is a reference value 1, and a certain length It is calculated by integrating the contact length CL (x ₁ ) of a certain width direction position x ₁ when the length Pt is a reference length.
In this way, the tire model elements can be given a degree of freedom, and the calculation of the weighting coefficient wc can be uniformly processed, thereby facilitating easy calculation.

  Furthermore, in this embodiment, the weighting factor wc (x) corresponding to the tire width direction position x of the extracted pixel is calculated by interpolating the weighting factors wc at a plurality of locations in the tire width direction WD. In this way, even if the coordinates for calculating the contact pressure by the finite element method and the coordinates of the pixels do not match, the weighting coefficient wc can be calculated by interpolation, and user-friendly analysis becomes possible.

The computer program according to the present embodiment is a program for causing a computer to execute each step constituting the tire snow / snow performance value calculation method.
By executing these programs, it is possible to obtain the operational effects of the above method. In other words, it can be said that the above method is used.

  As mentioned above, although embodiment of this invention was described based on drawing, it should be thought that a specific structure is not limited to these embodiment. The scope of the present invention is shown not only by the above description of the embodiments but also by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  The structure employed in each of the above embodiments can be employed in any other embodiment. The specific configuration of each unit is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 12 ... Sipe 21 ... Ground pressure calculation part 22 ... Weight coefficient calculation part 23 ... Extraction part 24 ... Index value calculation part P ... Ground pressure wc ... Weight coefficient S1 ... Base point L1, L2 ... Line PL ... Cumulative value of front-back direction ground pressure CL: contact length x, x ₁ ... tire width direction position

Claims (7)

Using a tire model in which a tire without a sipe formed on the tread is modeled with multiple elements, a ground analysis is performed by a finite element method under a predetermined load, and the contact surface shape and the contact pressure for each element constituting the contact surface Calculating steps,
A step of calculating a plurality of weighting factors corresponding to the cumulative values of the contact pressures of all the elements on a certain position in the tire width direction based on the contact analysis results by varying the width direction positions;
Extracting a pixel of a part having an edge effect according to a predetermined sliding direction from a sipe image to be evaluated with an arrangement position and orientation set on the tread;
Identifying the weighting coefficient corresponding to the position in the tire width direction of the pixel for each extracted pixel, accumulating the identified weighting coefficient and setting the accumulated value as an index value of ice and snow performance;
The calculation method of the tire snow-and-snow performance value.   The weighting coefficient at a certain width direction position is obtained when the ground pressure at the certain width direction position on the line along the width direction passing through the base point set on the ground surface and the pressure value at the base point are set as reference values. The cumulative value of the contact pressure of the line along the front-rear direction passing through the base point and the contact length at the position in the certain width direction when a certain length is set as a reference length are calculated. The calculation method of the tire snow and snow performance value of description.   3. The method for calculating a tire / ice / snow performance value according to claim 1, wherein the weighting coefficient corresponding to the position of the extracted pixel in the tire width direction is calculated by interpolating the weighting coefficient at a plurality of locations in the tire width direction. Using a tire model in which a tire without a sipe formed on the tread is modeled with multiple elements, a ground analysis is performed by a finite element method under a predetermined load, and the contact surface shape and the contact pressure for each element constituting the contact surface A contact pressure calculation unit for calculating
Based on the calculation result of the contact pressure calculation unit, a weighting factor calculation that calculates a plurality of weighting factors corresponding to the cumulative value of the contact pressures of all elements on a certain position in the tire width direction with different width direction positions. And
An extraction unit that extracts pixels of a part having an edge effect according to a predetermined sliding direction from a sipe image to be evaluated with an arrangement position and orientation set on the tread;
An index value calculation unit that identifies the weighting coefficient corresponding to the tire width direction position of the pixel for each pixel extracted by the extraction unit, accumulates the identified weighting coefficient, and uses the accumulated value as an index value of ice and snow performance;
An apparatus for calculating a performance value of tire snow and snow.   The weighting coefficient at a certain width direction position is obtained when the ground pressure at the certain width direction position on the line along the width direction passing through the base point set on the ground surface and the pressure value at the base point are set as reference values. The cumulative value of the contact pressure of the line along the front-rear direction passing through the base point and the contact length at the position in the certain width direction when a certain length is used as a reference length are calculated by adding them together. The tire snow and snow performance value calculation device described.   The tire ice / snow performance value calculation device according to claim 4 or 5, wherein the weighting coefficient corresponding to the position of the extracted pixel in the tire width direction is calculated by interpolating the weighting coefficient at a plurality of locations in the tire width direction. Using a tire model in which a tire without a sipe formed on the tread is modeled with multiple elements, a ground analysis is performed by a finite element method under a predetermined load, and the contact surface shape and the contact pressure for each element constituting the contact surface Calculating steps,
A step of calculating a plurality of weighting factors corresponding to the cumulative values of the contact pressures of all the elements on a certain position in the tire width direction based on the contact analysis results by varying the width direction positions;
Extracting a pixel of a part having an edge effect according to a predetermined sliding direction from a sipe image to be evaluated with an arrangement position and orientation set on the tread;
Identifying the weighting coefficient corresponding to the position in the tire width direction of the pixel for each extracted pixel, accumulating the identified weighting coefficient and setting the accumulated value as an index value of ice and snow performance;
A computer program that causes a computer to execute