JP2660954B2 - Method for selecting tread pattern of tire and vehicle equipped with tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a groove having an angle with respect to the traveling direction of a vehicle so as to travel on an inclined road surface.
The present invention relates to a method of setting a tread pattern of a tire that can exhibit high straightness, and a vehicle equipped with a tire having a tread pattern set.

[0002]

2. Description of the Related Art In general, a road surface on which a vehicle travels is often inclined downward from the center of the runway toward the road shoulder in order to improve drainage. A force that tries to slide down trying to lower the slope acts, for example, when you release the handle,
A so-called one-sided flow phenomenon of a vehicle, which is displaced to one side with respect to the straight traveling direction line and flows sideways, often occurs. As a countermeasure against such a problem, it has been controlled to generate (RCF) in a direction to cancel the road surface inclination by adjusting the breaker sticking direction / breaker rigidity. However, a significant change in (RCF) cannot be expected in a structure range that can be usually taken, and in many cases, a sufficient effect cannot be obtained. In addition, the force for causing the vehicle to skid due to the inclination of the road surface varies greatly depending on the vehicle weight, making it difficult to respond.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to improve the straightness by selecting a tire having a residual cornering force having an appropriate tread pattern in accordance with the weight of a vehicle. It is an object of the present invention to provide a method for selecting a tread pattern of a tire according to a vehicle weight, and a vehicle having a vehicle weight appropriate for a tire having the selected tread pattern.

[0004]

The method of selecting a tread pattern of a tire according to the weight of a vehicle according to the present invention includes a groove (groove) and a siping provided at an angle of 90 degrees or less with respect to the tire rotation axis direction. In the tire, a portion from a contact center, which is a center in a rotation direction of the contact surface of the tire, to a contact end, which is an axial end of the contact surface, is divided into three equal portions, a crown portion, a middle portion, and a shoulder portion, and the vehicle weight M (kg). A tire having a tread pattern having a pattern index PI having a residual cornering force RCF unique to the tread pattern in the following range is mounted on a certain vehicle. In 0.9 ≦ (60 · PI + 900 ) /M≦1.1 Here, the pattern index PI _{is, PI = (ΔRCF CR + ΔRCF} SH) + (ΔRCF CR1 +
ΔRCF _SH1 ) (ΔRCF _CR + ΔRCF _SH ) is a residual cornering force by the groove of the tread pattern, and is obtained by the following equation. _{Crown: ΔRCF CR = Σ (-0.020 ·} m · α · θ) Shoulder _{portion: ΔRCF SH = Σ (0.047 ·} n · β · δ) (ΔRCF CR1 + ΔRCF SH1) is in residual cornering force by sipes in the tread pattern ,
It is obtained by the following equation. Crown part: ΔRCF _CR1 = Σ (-0.020 · m ₁ · α ₁
・ Θ ₁ ) Shoulder: ΔRCF _SH1 = Σ (0.021 ・ n ₁・ β ₁
Δ ₁ ) where m: number of grooves in the crown portion in the tire contact surface n: number of grooves in the shoulder portion in the tire contact surface α: the number of grooves relative to the length of the crown portion in the crown portion in the tire contact surface Ratio of axial length θ: Angle formed by the groove in the crown portion in the tire contact surface with respect to the tire axial direction β: Ratio of the axial length of the groove to the length of the shoulder portion in the shoulder portion in the tire contact surface δ: Angle formed by the groove in the shoulder portion in the tire contact surface with respect to the tire axial direction m ₁ : Number of sipes in the crown portion in the tire contact surface n ₁ : Number of sipes in the shoulder portion in the tire contact surface α ₁ the ratio of the sipes axial length of the relative length of the crown portion of the crown portion of the tire ground contact surface theta ₁ Angle beta ₁ forms with respect to the tire axial direction of the sipes in the crown portion of the tire ground contact surface: tire ratio of the axial length of the sipes relative to the length of the shoulder portion in the shoulder portion in the ground plane [delta] _1: tire contact plane The angle formed with respect to the axial direction of the sipe in the shoulder portion of the tire according to the vehicle weight M, by selecting a tire having a pattern index PI that can obtain an appropriate tread pattern-specific residual cornering force RCF,
It is possible to suppress the flow of the vehicle and improve the straightness. A vehicle having a vehicle weight M equipped with a tire having a tread pattern having the pattern index PI,
The pattern index PI and the vehicle weight M satisfy the condition 0.9 ≦ (60 · PI + 900) /M≦1.1. By setting the vehicle having a vehicle weight M that satisfies a predetermined condition with respect to the pattern index PI of the tread pattern of the tire, it is possible to suppress the lateral flow of the vehicle, improve the straightness, and obtain stable running performance. .

[0005]

An embodiment of the present invention will be described with reference to the drawings.
In FIG. 1, a tread pattern formed on the surface of a tread 1 of a tire includes a pair of tread patterns extending substantially parallel to each other at a relatively narrow interval in a tire circumferential direction, that is, a tire traveling direction (arrow F) at a center portion in a tread width direction. Zigzag first main groove 2,
A pair of zigzag-shaped second main grooves 3 and 3 extending outward in the tire circumferential direction from the first main grooves 2 and 2 on both sides in the tire width direction outward in the tire width direction; A pair of zigzag first sub-grooves 4, 4, which are thinner than the two main grooves 2, 3, and are formed near the end of the tread 1. Pair of second linear members extending in the circumferential direction
Grooves extending across the sub-grooves 5, 5 and 51, 51 and the first sub-groove 4 and having both ends connected to the first main groove 2 and the second main groove 3 and formed at an angle θ with respect to the tire axial direction. A second groove 7 having both ends connected to the first groove 6, the second main groove 3 and the second sub groove 5, and formed at an angle δ with respect to the tire axial direction, and a side wall of the first main groove 2. First siping 8 formed at an angle θ ₁ outward in the tire axial direction from
And an angle δ ₁ from the side wall of the second main groove 3 to the outside in the tire axial direction.
And the auxiliary sipes 10 and 11 extending from the side walls of the first main groove 2 and the second main groove 3 toward the center of the tire tread, respectively.

A line FL and a distance SL are provided between a grounding center CL (mostly coincident with the tread center line) which is the center of the grounding surface of the tread 1 and a grounding end OL which is an axial end of the grounding surface. w, and is divided into three equal parts, the crown part CR, the middle part MID, and the shoulder part SH in this order from the grounding center CL side.
And

Next, the remaining cornering force RCF of the tread pattern on the ground contact surface will be described. In the ground contact surface, the pattern contributing to the increase in the residual cornering force RCF is not the first main groove 2, the second main groove 3, and the first sub-groove 4 in the tire circumferential direction, but grooves and sipes extending in the tire axial direction. In addition, the groove and siping provided in the crown portion CR and the shoulder portion SH extend outward in the tire axial direction, and the groove and siping located in the middle portion MID hardly contribute.

The groove 6 at the crown CR has a shape that rises to the right and has a negative (-) effect on the increase in the residual cornering force RCF. The contribution ΔRCF _CR to the residual cornering force RCF is calculated by the following equation. You. ΔRCF _CR = Σ (−0.020 · m · α · θ) where m: number of grooves 6 located in crown CR α: ratio of axial length s of groove 6 to width w of crown CR θ: Angle of groove 6 with counterclockwise direction positive with respect to tire axial direction

The groove 7 in the shoulder SH is
The shape that rises to the right has a positive (+) effect on the increase in the residual cornering force RCF, and the contribution ΔRCF _SH to the residual cornering force RCF is calculated by the following equation. ΔRCF _SH = Σ (0.047 · n · β · δ) where n is the number of grooves in the shoulder SH and β is the shoulder S with respect to the length w of the shoulder SH.
Ratio of the axial length d of the groove 7 located in H. δ: An angle with the counterclockwise direction being positive with respect to the tire axial direction of the groove 7.

The siping 8 in the crown CR is
The shape that rises to the right has a negative (-) effect on the increase in the residual cornering force RCF, and the contribution ΔRCF _CR1 to the residual cornering force RCF is calculated by the following equation. ΔRCF _CR1 = Σ (−0.020 · m ₁ · α ₁ · θ ₁ ) where m _{1 is} the number of sipes 8 in the crown CR α ₁ : the axial length s ₁ of the siping 8 with respect to the length w of the crown CR. Ratio θ ₁ : Angle with the counterclockwise direction positive with respect to the tire axial direction of siping 8

Siping 9 at shoulder SH
Is the residual cornering force RCF with the shape rising to the right
Has a positive (+) effect on the increase of the residual cornering force RCF, and the contribution ΔRCF _SH to the residual cornering force RCF is calculated by the following equation. ΔRCF _SH1 = Σ (0.021 · n ₁ · β ₁ · δ ₁ ), where n _{1 is} the number of sipes 9 in the shoulder SH. Β ₁ is the siping 9 for the length w of the shoulder SH.
Of the axial length d ₁ ratio [delta] _1: angle a counterclockwise direction is positive with respect to the tire axial direction of the sipes 9

A pattern index PI is calculated by the following equation based on the contribution of the RCF to the calculated residual cornering force. _{PI = (ΔRCF CR + ΔRCF SH} ) + (ΔRCF CR1 +
ΔRCF _SH1 ) where (ΔRCF _CR + ΔRCF _SH ) is the contribution of the groove, and (ΔRCF _CR1 + ΔRCF _SH1 ) is the contribution of the siping. FIG. 2 shows the value of the residual cornering force RCF with respect to the pattern index PI. A straight line A indicates a reference array tire in which the arrangement direction of the breaker cords embedded in the tire tread is normal, and a straight line B indicates the breaker. The arrangement direction of the cords is the reverse direction to the reference arrangement tire, that is, an inverted arrangement tire arranged in a direction symmetric with respect to the tire rotation direction, and the residual cornering force RCF is changed by changing the arrangement direction of the breaker cords. A difference of 14 to 15 kg.

Next, a pattern index PI of a tire mounted on a vehicle body having a vehicle weight M (kg) is set to a range calculated by the following equation. 0.9 ≦ (60 · PI + 900) /M≦1.1 For example, if the body weight is 800kg, -3 ≦ PI
≤-0.3, and 3 for vehicle body weight M 1200kg
≤ PI ≤ 7.

Embodiments 1 and 2 of a tire to which the present invention is applied
The results of a vehicle flow test that measures the left and right displacements when traveling 100 m on a flat road surface at 80 km / h using the conventional structures 3, 4 and the comparative examples A, B, C and D. Are shown in the following Table 1 (Example) and Table 2 (Comparative Example). [Table 1] Example 1 Example 2 Example 3 Example 4 Tire size 155 / 70R13 155 / 70R13 185 / 70R13 185 / 70R13 Vehicle weight 820 820 1160 1160 PI−2.0 0.0 3.0 6.0 (60 · PI + 900) / M 0.95 1.10 0.93 1.09 Vehicle flow test result Left 0.2 Right 0.3 Left 0.3 Right 0.3 [Table 2] Comparative example A Comparative example B Comparative example C Comparative example D Tire size 155 / 70R13 155 / 70R13 185 / 70R13 185 / 70R13 Vehicle weight 820 820 1160 1160 PI − 4.0 2.0 0.0 9.0 (60 ・ PI + 900) / M 0.80 1.24 0.78 1.24 Vehicle flow test result left 1.8 right 2.0 left 2.2 right 2.1

As is clear from Tables 1 and 2, 0.9 ≦
By selecting a tire having a PI within the range of (60 · PI + 900) /M≦1.1, the flow of the vehicle can be reduced. That is, when the vehicle travels straight on a flat road surface and a road surface inclined in the direction of the road shoulder, which is a direction intersecting with the vehicle traveling direction, stable straight traveling performance can be obtained.

In a vehicle having a vehicle weight M equipped with a tire having a tread pattern having the above-mentioned pattern index PI, the pattern index PI and the vehicle weight M satisfy the condition 0.9 ≦ (60 · PI + 900) /M≦1.1. Use a satisfactory vehicle. According to this configuration, the vehicle has a vehicle weight M that satisfies a predetermined condition with respect to the pattern index PI of the tread pattern of the tire, thereby suppressing the lateral flow of the vehicle, improving the straightness, and achieving stable running performance. Can be obtained.

[0017]

Since the present invention is configured as described above, the following effects can be obtained. By selecting a tire having a pattern index capable of obtaining an appropriate residual cornering force unique to the tread pattern according to the vehicle weight, it is possible to suppress the flow of the vehicle and improve the straightness. Further, by setting the vehicle having a vehicle weight that satisfies a predetermined condition with respect to the pattern index of the tread pattern of the tire, the lateral flow of the vehicle is suppressed,
It is possible to obtain a stable running performance by improving straightness.

[Brief description of the drawings]

FIG. 1 is a development view of a tire tread pattern to which the present invention is applied.

FIG. 2 is a graph showing a residual cornering force RCF with respect to a pattern index PI.

[Explanation of symbols]

1 tread, 2nd main groove, 3rd main groove, 4th
Sub-groove, 5 Second sub-groove 6 1st groove, 7 2nd groove, 8 1st siping 9 2nd siping, 10, 11 auxiliary siping

Claims (2)

(57) [Claims] In a tire provided with a groove and a siping, a portion from a contact center to a contact end of the tire is equally divided into a crown portion, a middle portion and a shoulder portion, and a vehicle weight M is increased.
A tire tread pattern selection method according to vehicle weight, wherein a tire having a tread pattern having a pattern index PI in the following range is mounted on a vehicle having a weight (kg). 0.9 ≦ (60 · PI + 900 ) /M≦1.1 PI = (ΔRCF CR + ΔRCF SH) + (ΔRCF CR1 +
ΔRCF _SH1 ) ΔRCF _CR = Σ (−0.020 · m · α · θ) ・ ・ ・ ・ ・ ・
..Sum of (−0.020 · m · α · θ) in the ground plane ΔRCF _SH = Σ (0.047 · n · β · δ)
··· Total sum of (0.047 · n · β · δ) in the ground contact plane ΔRCF _CR1 = (-0.020 · m ₁ · α ₁ · θ ₁ ) · · ·
..In the ground plane (-0.020 · m ₁ · α ₁ · θ ₁ )
ΔRCF _SH1 = Σ (0.021 · n ₁ · β ₁ · δ ₁ ) ···
··· Total of (0.021 · n ₁ · β ₁ · δ ₁ ) in the ground contact surface where m: number of grooves in the crown portion in the tire contact surface n: number of grooves in the shoulder portion in the tire contact surface α: The ratio of the axial length of the groove to the length of the crown in the crown portion in the tire contact surface θ: the angle formed by the groove in the crown portion in the tire contact surface in the tire axial direction β: the shoulder in the tire contact surface Ratio of the length of the groove in the axial direction to the length of the shoulder portion in the portion δ: Angle formed by the groove in the shoulder portion in the tire contact surface with respect to the tire axial direction m ₁ : Number of sipes in the crown portion in the tire contact surface n _1: a tire ground plane in the shoulder portion sipes of the number of α ₁ in of: the length of the crown portion of the crown portion of the tire ground plane The ratio of the axial length of the sipes θ with respect to _1: tire contact plane angle beta ₁ forms with respect to the tire axial direction of the sipes in the crown portion: axial sipes to the length of the shoulder portion in the shoulder portion of the tire ground contact surface Direction length ratio δ ₁ : Angle formed with respect to the tire axial direction of siping at the shoulder in the tire contact surface 2. A vehicle having a vehicle weight M equipped with a tire provided with a tread pattern having a pattern index PI according to claim 1, wherein the pattern index PI and the vehicle weight M satisfy the following condition. Features vehicle. 0.9 ≦ (60 · PI + 900) /M≦1.1