JP4580087B2 - Tire tread profile deployment method - Google Patents

Description

【００４２】
【表２】

【００４３】
【発明の効果】
上述したように、本発明は、断面サイズに基づく二次元的要素だけでなく、タイヤ性能への影響力が非常に大きい接地性を充分に考慮して展開トレッドプロファイルを決定しているため、タイヤ基準モデルが有する優れた性能、とりわけ乗り心地性を展開タイヤに充分に反映することができ、このタイヤ基準モデルの性能傾向を有するタイヤを高精度でシリーズ化しうる。又サイズ展開の信頼性が大巾に高まり、開発段階における展開タイヤの性能確認の手間を省くことも可能となる。
【図面の簡単な説明】
【図１】本発明の展開方法における処理手順の一例を示すフローチャートである。
【図２】基準トレッドプロファイルの関数表示を説明する平面図である。
【図３】仮展開三次元トレッドプロファイル及びそのスライスカットを説明する斜視図である。
【図４】（Ａ) は、タイヤ基準モデルのトレッドプロファイル及びカット断面、（Ｂ）〜（Ｄ）はその展開タイヤのトレッドプロファイル及びカット断面を示す線図である。
【図５】（Ａ) 〜（Ｄ）は、他の展開タイヤのトレッドプロファイル及びカット断面を示す線図である。
【図６】（Ａ) 〜（Ｄ）は、他の展開タイヤのトレッドプロファイル及びカット断面を示す線図である。
【図７】（Ａ) 〜（Ｄ）は、他の展開タイヤのトレッドプロファイル及びカット断面を示す線図である。
【図８】（Ａ) 、（Ｂ）は、他の展開タイヤのトレッドプロファイル及びカット断面を示す線図である。
【図９】（Ａ）はタイヤ基準モデルと展開タイヤとをサイズ比較した線図、（Ｂ）は従来のトレッドプロファイルの展開手段を説明する線図である。
【符号の説明】
２ｅ トレッド縁
３ カット断面
Ａ タイヤ基準モデル
Ｂ 展開タイヤ
Ｆａ 基準トレッドプロファイル
Ｆｂ 展開トレッドプロファイル
Ｆｂ’ 仮展開トレッドプロファイル
Ｇｂ 使用荷重
Ｈａ 断面高さ
Ｈｂ 断面高さ
Ｉ タイヤ回転軸
Ｋｂ 目標接地巾
Ｋｘｙ 巾方向長さ
Ｐｂ 使用内圧
Ｓｂ 目標接地面積
Ｓｘｙ カット断面積
Ｖｂ’ 仮展開三次元トレッドプロファイル
Ｗａ 呼び巾
Ｗｂ 呼び巾
α 巾方向比初期値
β 方向比初期値
δ カット深さ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tire tread profile developing method for determining a developed tread profile of a developed tire B having a tire size different from that of the tire reference model A, from the developed reference tread profile of the tire reference model A.
[0002]
[Prior art]
The tread surface of the tire is the part that contacts the road surface during driving, and its contour shape (tread profile) has a great influence on various performances such as straight running stability, steering stability, riding comfort, and wear resistance of the tire. Therefore, various developments of tread profiles are underway.
[0003]
On the other hand, development of such a tread profile is generally performed for a tire of a specific size, and then the tread profile is developed in order to reflect the tire characteristics to those of other tire sizes. Is called. In other words, the developed tread profiles of the developed tires having different tire sizes are determined from the developed tread profile of the tire reference model, and the tires having the performance tendency of the tire reference model are serialized.
[0004]
At this time, the conventional developed tread profile pb is determined by comparing the tire sizes of the tire reference model A and the developed tire B, as shown in FIG. And the nominal width Wa of the tire reference model A, the width direction ratio α, and the ratio Hb / Ha of the section height Hb of the developed tire B and the section height Ha of the tire reference model A. The direction ratio β is obtained. Then, as shown in FIG. 9B, the developed tread profile pb is determined by enlarging (or reducing) the reference tread profile pa in the width direction and the height direction at the magnifications α and β. .
[0005]
[Problems to be solved by the invention]
That is, the conventional developed tread profile pb is set by only two-dimensional elements based on the cross-sectional sizes of the tire reference model A and the developed tire B, and is a three-dimensional element such as ground contact having a great influence on the tire performance. The lack of consideration.
[0006]
As a result, there is a problem that the excellent performance of the tire reference model cannot be sufficiently reflected on the developed tire, for example, the tire characteristics change at the time of deployment. For this reason, a lot of time, labor, and cost are consumed, such as the need to sufficiently check the performance of the deployed tire at the development stage.
[0007]
Therefore, the present invention has an excellent tire reference model based on determining a developed tread profile in consideration of not only a two-dimensional element based on a cross-sectional size but also a contact area and a contact width related to a tire contact property. Providing a tire tread profile deployment method that can fully reflect performance, particularly ride comfort, in deployment tires, increase the reliability of size development, and greatly save the effort of checking the performance of deployed tires in the development stage It is an object.
[0008]
[Means for Solving the Problems]
The invention according to claim 1 of the present invention is based on the developed tread profile of the tire reference model A, and the developed tread profile of the developed tire B having a tire size different from that of the tire reference model A is referred to as the tire reference model A. Tire tread profile deployment method to determine the performance trend of
Displaying a reference tread profile with the function Fa = F (x, y) = 0 between tread edges;
A contact width setting step for obtaining a target contact width Kb of the developed tire;
Obtaining a target ground contact area Sb by dividing the use load Gb of the developed tire B defined by the tire standard by the use internal pressure Pb;
When the function F (x, y) = 0 of the tire reference model A is 0, the width direction ratio initial value α is determined by the ratio (Wb / Wa) between the nominal width Wb of the developed tire B and the nominal width Wa of the tire reference model A, and The initial value β of the height direction ratio is determined by the ratio (Hb / Ha) between the cross-sectional height Hb of the developed tire B and the cross-sectional height Ha of the tire reference model A, and the temporarily developed tread profile is expressed by the function Fb = F (x · obtaining by α, y · β) = 0;
Obtaining a provisionally developed three-dimensional tread profile by rotating the provisionally developed tread profile about a tire rotation axis;
Slicing and cutting the temporarily developed three-dimensional tread profile until the cut cross-sectional area Sxy coincides with the target ground contact area Sb, and comparing the width direction length Kxy of the cut cross-section with the target ground contact width Kb;
When the width direction length Kxy and the target ground contact width Kb do not coincide with each other, at least the height direction ratio initial value β is changed and the provisionally developed tread profile is changed until they coincide with each other. A calculation step for obtaining the developed tread profile having the same contact width Kb.
In the contact width setting step, the target contact width Tb is smaller than the developed tire nominal width Wb × (−0.60 × flatness + 1.116) and the developed tire nominal width Wb × (−0. 48 × flat rate + 0.893).
[0009]
In the invention of claim 2, the cut cross-sectional area Sxy and the target ground contact area Sb, and the width direction length Kxy and the target ground contact width Kb are identical when the ratio is 2.0% or less. Then, it is determined that it is determined.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The tire tread profile deployment method according to the first aspect of the invention is illustrated in a flowchart in FIG.
(1) displaying the reference tread profile Fa with the function F (x, y) = 0;
(2) A contact width setting step for obtaining a target contact width Kb from the tire size of the developed tire B;
(3) A step of obtaining a target contact area Sb of the developed tire B from the use load Gb and the use internal pressure Pb defined in the tire standard;
(4) A step of obtaining a provisionally developed tread profile Fb ′ as a function F (x · α, y · β) = 0 from the function F (x, y) = 0 of the reference tread profile Fa;
(5) obtaining a provisionally developed three-dimensional tread profile Vb ′ obtained by rotating the provisionally developed tread profile Fb ′ around the tire rotation axis I;
(6) The provisionally developed three-dimensional tread profile Vb ′ is slice-cut, and the width direction length Kxy of the cut section 3 when the cut sectional area Sxy coincides with the target ground contact area Sb and the target ground contact width Kb. A step of comparing;
(7) When the width direction length Kxy and the target ground contact width Kb do not match, the provisional deployment tread profile Fb ′ is changed until they match, so that the width direction length Kxy matches the target ground contact width Kb. A calculation step for obtaining Fb;
Is included.
[0012]
In step (1), as shown in FIG. 2, the reference tread profile Fa of the developed tire reference model A is displayed and specified by the function F (x, y) = 0 between the tread edges 2e and 2e. It is.
[0013]
As is well known, this reference tread profile Fa is the contour line of the tread surface 2 in the tire meridian section including the tire rotation axis I. In this example, for convenience, the bead base line is the x axis and the tire equator is the y axis. What is displayed in the xy orthogonal coordinates is illustrated. It is also possible to use XY orthogonal coordinates with the tire rotation axis I as the X axis and the tire equator as the Y axis. At this time, coordinate conversion is performed with X = x and Y = y + 0.5 · D (D is the rim). Of nominal diameter). As described above, the function F (x, y) = 0 can include functions displayed in various coordinate systems such as polar coordinates (r, θ), for example, as long as the coordinate conversion is possible. It may be a combination of multiple functions.
[0014]
Next, the step (2) is a step of obtaining a target ground contact width Kb satisfying the following expression (1) from the tire size of the developed tire B.
Wb × (−0.60 × flat rate + 1.116)>Kb>
Wb × (−0.48 × flat rate + 0.893) −−− (1)
Here, in the tire size display, for example, when a nominal flat rate such as “195 / 60R14” is displayed, this nominal flat rate is used. Also, for example, when the nominal flatness such as “7.5R16” is not displayed, the flatness calculated from the design cross-sectional width, the design outer diameter, the rim diameter, etc. defined in the tire standard for the tire size is set. use.
[0015]
This equation (1) has been found from various experimental results by the present inventor, and among the various tire performances such as straight running stability, steering stability, riding comfort, and wear resistance, the riding comfort is particularly high. This shows the ratio of the ground contact width to the nominal width necessary for sufficiently reflecting the property to the developed tire. Therefore, when the formula (1) is not satisfied, it is difficult to sufficiently inherit the riding comfort in the tire reference model A. From such a viewpoint, it is preferable that the tire reference model A also satisfies the formula (1).
[0016]
In addition, it is preferable that the target ground contact width Kb further satisfies the following expression (1) ′ from the above point.
Kb = 0.890 × Wb−1.505 × (flatness) +68.051 (1) ′
[0017]
Next, step {circle around (3)} is a step of obtaining the target contact area Sb using the following equation (2) from the use load Gb and the use internal pressure Pb of the developed tire B specified in the tire standard.
Sb = Gb / Pb (2)
[0018]
Here, the internal pressure Pb is the maximum air pressure if the tire standard is JATMA, the maximum value listed in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” if it is TRA, and “INFLATION PRESSURE” if it is ETRTO. In particular, it is 200 kPa for passenger car tires. The load Gb is 66% of the maximum load capacity for JATMA, 66% of the maximum value listed in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” for TRA, and “LOAD CAPACITY” for ETRTO. Of 66%.
[0019]
In general, the thin film theory can be applied to a pressure vessel such as a balloon that can ignore bending rigidity. In this thin film theory, for example, when a balloon is pressed against a plane with a load g, the contact area s between the plane and the balloon is approximately obtained as a value obtained by dividing the load g by the filling internal pressure p (s = g / p). It can be done.
[0020]
The tire actually has bending stiffness, and the stiffness distribution differs between the tread portion and the sidewall portion. However, it has been empirically and experimentally confirmed that the tire contact area is very close to the target contact area Sb obtained by dividing the tire use load Gb by the use internal pressure Pb as described above. ing.
[0021]
Therefore, in the present invention, steps (4) to (7) described below are performed, and a conventional profile obtained two-dimensionally based on the cross-sectional size from the reference tread profile Fa is converted into a temporarily developed tread profile Fb ′. In addition, the provisionally developed tread profile Fb ′ can be gradually changed to form a ground plane having both a ground contact area that matches the target ground contact area Sb and a ground contact width that matches the target ground contact width Kb. The provisional development tread profile Fb ′ is found and determined as the development tread profile Fb.
[0022]
That is, in step (4), the provisional development tread profile Fb ′ is obtained as the function F (x · α, y · β) = 0 from the function F (x, y) = 0 of the reference tread profile Fa.
[0023]
Specifically, as shown in FIGS. 9A and 9B, the cross-sectional sizes of the tire reference model A and the developed tire B are compared with each other as in the prior art, and the nominal width Wb of the developed tire B and the tire reference model A are compared. The width direction ratio initial value α by the ratio Wb / Wa to the nominal width Wa, and the height direction ratio initial value β by the ratio Hb / Ha of the section height Hb of the developed tire B and the section height Ha of the tire reference model A Determine. α = Wb / Wa and β = Hb / Ha.
[0024]
Then, by expanding (or reducing) the reference tread profile Fa at a rate of α times in the x-axis direction and β times in the y-axis direction, the provisionally developed tread profile Fb ′ is converted into a function F (x · α, y · β). ) = 0.
[0025]
Here, what is different from the prior art is that the function F (x · α, y · β) = 0 is the final developed tread profile pb in the prior art, whereas in the present invention, this function F (x · α, y · β) = 0 is only a starting point for obtaining the developed tread profile Fb.
[0026]
Next, in step (5), the provisionally developed tread profile Fb ′ is rotated about the tire rotation axis I (corresponding to the X axis in the present example), as shown in FIG. A provisionally developed three-dimensional tread profile Vb ′ is specified on the Z coordinate. The provisionally developed three-dimensional tread profile Vb ′ does not necessarily have to be continuously 360 °, and may be specified within a range necessary for estimating the ground contact shape.
[0027]
Next, in step (6), as shown in FIG. 3, the provisionally developed three-dimensional tread profile Vb ′ is slice-cut until the cut sectional area Sxy coincides with the target ground contact area Sb. The width direction length Kxy is compared with the target ground contact width Kb.
[0028]
Specifically, the provisionally developed three-dimensional tread profile Vb ′ is cut (slice cut) along a plane 5 parallel to the virtual road surface, and a cut cross-sectional area Sxy of the cut cross-section 3 that is the cut surface is calculated. Then, the slice cut is repeated while changing the cut depth δ of the plane 5 from the surface of the profile Vb ′ until the cut sectional area Sxy coincides with the target ground contact area Sb. Specifically, for example, the step value Δδ is sequentially added to the cut depth δ. Then, the width direction length Kxy of the cut section 3 when Sxy≈Sb is compared with the target ground contact width Kb.
[0029]
The plane 5 is a plane parallel to the tire rotation axis I, and in this example, a plane orthogonal to the Z axis. Therefore, the cut section 3 is a plane when the maximum radius of the provisionally developed three-dimensional tread profile Vb ′ is Rmax. A function f (X, Y) = of a curve obtained by simultaneously combining the equation Z = (Rmax−δ) of 5 and the curved surface equation G (X, Y, Z) = 0 of the temporarily developed three-dimensional tread profile Vb ′ = It can be obtained as 0. Further, by integrating the function f (X, Y) = 0 representing the contour of the cut section 3, the cut section area Sxy that is the estimated ground contact area can be calculated.
[0030]
The cut cross section 3 is approximated as a ground contact shape in a straight traveling state on the condition that the cut cross sectional area Sxy and the target ground contact area Sb coincide (Sxy≈Sb). Is estimated.
[0031]
Further, in the present invention, under the condition of Sxy≈Sb, the width direction length Kxy of the cut section 3 is compared with the target ground contact width Kb, and when they coincide (Kxy≈Kb), provisional development at that time is performed. The tread profile Fb ′ is determined as the final developed tread profile Fb. If they do not match, the next step (7) is performed.
[0032]
In step (7), at least the height direction ratio initial value β is changed, and the provisional development tread profile Fb ′ is changed until they match, whereby the width direction length Kxy and the target ground contact width Kb match. The developed tread profile Fb is obtained.
[0033]
In other words, the step value Δβ is added (or subtracted) to the height direction ratio initial value β (= Hb / Ha), and β + Δβ (or β−Δβ) is replaced with the initial value β as the height direction ratio βi. The provisional development tread profile Fb ′ is reset as a new function F (x · α, y · βi) = 0. Thereafter, the steps (5) and (6) are repeated to compare the width direction length Kxy with the target ground contact width Kb. Until the width direction length Kxy and the target ground contact width Kb coincide with each other, this “re-setting of the temporarily developed tread profile Fb ′ by changing the value of the height direction ratio βi” → “step (5)” → “step (6) "is repeated sequentially.
[0034]
Note that the change in the height direction ratio βi can be quickly performed in the target development tread profile Fb by sequentially performing the change in the direction in which the value increases or decreases based on the initial value β as in this example. Preferred to reach. Note that the resetting of the temporary development tread profile Fb ′ may be performed by changing the width direction ratio initial value α in the same manner.
[0035]
Thus, in the tire tread profile developing method of the present embodiment, the conventional profile obtained based on the cross-sectional size is set as the temporary developed tread profile Fb ′. Then, the shape of the provisionally developed tread profile Fb ′ is gradually changed by a predetermined method, and the estimated ground contact area (corresponding to the cut cross-sectional area Sxy) that matches the target ground contact area Sb and the estimation that matches the target ground contact width Kb. A provisionally developed tread profile Fb ′ capable of forming an estimated ground contact surface (corresponding to the cut section 3) having both a ground contact width (corresponding to the width direction length Kxy) is found, and this provisionally developed tread profile Fb ′ is developed as a developed tread profile. It is determined as Fb.
[0036]
Therefore, in the developed tire B having the developed tread profile Fb set by the deployment method, since the ground contact property having a great influence on the tire performance is sufficiently taken into consideration, the excellent performance of the tire reference model A is obtained. In particular, it is possible to fully inherit the ride comfort and to series tires having the performance tendency of the tire reference model with high accuracy. This also greatly increases the reliability of the size development, and it is possible to save the trouble of checking the performance of the developed tire at the development stage.
[0037]
The target ground contact width Kb set in the ground contact width setting step {circle around (2)} is indispensable for riding comfort as described above. When planning, the ratio Kb / Wb of the target ground contact width Kb to the nominal width Wb is preferably substantially equal in the developed tires B in the series.
[0038]
Here, in the present application, when the cut sectional area Sxy is in the range of 0.98 to 1.02 times the target ground contact area Sb, preferably in the range of 0.99 to 1.01 times, the cut It is determined that the cross-sectional area Sxy matches the target ground contact area Sb. Similarly, when the width direction length Kxy is in the range of 0.98 to 1.02 times the target ground contact width Kb, preferably in the range of 0.99 to 1.01 times, the width direction length is It is determined that the length Kxy matches the target ground contact width Kb.
[0039]
Further, the processing of steps (1) to (7) in the tire tread profile developing method can be easily performed using, for example, a computer. FIG. 1 is a flowchart showing an example of such a processing procedure. However, this is merely an example. In particular, if steps {circle around (2)} and {circle around (3)} are before step {circle around (6)}, The processing position can be changed as appropriate.
[0040]
【Example】
An example in which a developed tire having tire sizes shown in Tables 1 and 2 is determined from a tire reference model having a tire size of 215 / 45R15 using the development method of the present invention will be described. 4 to 8 show the determined tread profile and cut section of the developed tire together with the tread profile and cut section of the tire reference model.
[0041]
[Table 1]

[0042]
[Table 2]

[0043]
【The invention's effect】
As described above, in the present invention, the developed tread profile is determined in consideration of not only a two-dimensional element based on the cross-sectional size but also a ground contact property that has a great influence on the tire performance. The excellent performance of the reference model, particularly the ride comfort, can be fully reflected in the developed tire, and tires having the performance tendency of the tire reference model can be serialized with high accuracy. In addition, the reliability of size development is greatly increased, and it is possible to save the trouble of checking the performance of the developed tire at the development stage.
[Brief description of the drawings]
FIG. 1 is a flowchart showing an example of a processing procedure in a developing method of the present invention.
FIG. 2 is a plan view for explaining a function display of a reference tread profile.
FIG. 3 is a perspective view for explaining a provisionally developed three-dimensional tread profile and a slice cut thereof.
4A is a diagram showing a tread profile and a cut section of a tire reference model, and FIGS. 4B to 4D are diagrams showing a tread profile and a cut section of the developed tire. FIG.
FIGS. 5A to 5D are diagrams showing tread profiles and cut sections of other developed tires. FIGS.
FIGS. 6A to 6D are diagrams showing tread profiles and cut sections of other developed tires. FIGS.
FIGS. 7A to 7D are diagrams showing tread profiles and cut sections of other developed tires. FIGS.
FIGS. 8A and 8B are diagrams showing tread profiles and cut cross sections of other developed tires. FIGS.
FIG. 9A is a diagram comparing the size of a tire reference model and a developed tire, and FIG. 9B is a diagram illustrating a conventional tread profile developing means.
[Explanation of symbols]
2e Tread edge 3 Cut section A Tire reference model B Expanded tire Fa Reference tread profile Fb Expanded tread profile Fb 'Temporarily expanded tread profile Gb Load Ha Section height Hb Section height I Tire rotation axis Kb Target ground contact width Kxy Width direction length Pb Working internal pressure Sb Target ground contact area Sxy Cut cross-sectional area Vb ′ Temporarily developed three-dimensional tread profile Wa Nominal width Wb Nominal width α Initial value of width direction β Initial value of direction ratio δ Cut depth

Claims (2)

A tire tread profile for determining a developed tread profile of a developed tire B having a tire size different from that of the tire reference model A based on the developed tire reference model A with the performance tendency of the tire reference model A Deployment method,
Displaying a reference tread profile with the function Fa = F (x, y) = 0 between tread edges;
A contact width setting step for obtaining a target contact width Kb of the developed tire;
Obtaining a target ground contact area Sb by dividing the use load Gb of the developed tire B defined by the tire standard by the use internal pressure Pb;
When the function F (x, y) = 0 of the tire reference model A is 0, the width direction ratio initial value α is determined by the ratio (Wb / Wa) between the nominal width Wb of the developed tire B and the nominal width Wa of the tire reference model A, and The initial value β of the height direction ratio is determined by the ratio (Hb / Ha) between the cross-sectional height Hb of the developed tire B and the cross-sectional height Ha of the tire reference model A, and the temporarily developed tread profile is expressed by the function Fb = F (x · obtaining by α, y · β) = 0;
Obtaining a provisionally developed three-dimensional tread profile by rotating the provisionally developed tread profile about a tire rotation axis;
Slicing and cutting the temporarily developed three-dimensional tread profile until the cut cross-sectional area Sxy coincides with the target ground contact area Sb, and comparing the width direction length Kxy of the cut cross-section with the target ground contact width Kb;
When the width direction length Kxy and the target ground contact width Kb do not coincide with each other, at least the height direction ratio initial value β is changed and the provisionally developed tread profile is changed until they coincide with each other. A calculation step for obtaining the developed tread profile having the same contact width Kb.
In the contact width setting step, the target contact width Kb is smaller than the developed tire nominal width Wb × (−0.60 × flatness + 1.116) and the developed tire nominal width Wb × (−0. 48 × flattening rate + 0.893), a tire tread profile developing method, characterized in that   The cut cross-sectional area Sxy and the target ground contact area Sb, and the width direction length Kxy and the target ground contact width Kb are determined to coincide with each other when the ratio is 2.0% or less. The tire tread profile developing method according to claim 1.

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