JPH0427604A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To reduce rolling resistance of a tire by providing a ring groove which substantially continues at a buttress part which is a conversion part of a tread and a side wall in a circumferential direction concentric with the tread to ensure strength of the side wall and reduce hysteresis loss. CONSTITUTION:There are provided, in a tire 1, at least a tread part 2 which is formed into a circular shape, and a side wall 3 which extends from both the edges of the tread part 2 to its inside in a diametrical direction. With this constitution, on the side which comes into no contact with the ground, the distance from a tire maximum width position L of the side wall 3 to an outer circumferential surface of the tread part 2, namely, a tire maximum diameter part is taken as tire upper part sectional height H, and a position D which is apart from the tire maximum width position L by a prescribed distance h (however, h=(0.5+ or -0.05)H) is set on the side wall 3. Then a circular groove 9 in a prescribed depth which does not, reach carcass 6 is formed in a buttress Part 8 between the position D and a ground contacting edge E which is an edge part of the side wall 3 side of a ground contacting part, of the tread part 2 in a circumferential direction concentric with the tread part 2.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a tire that reduces rolling resistance by reducing hysteresis loss and heat generation in the tire tress area, which is the part of the tire that experiences the greatest distortion. .

[Prior Art] Generally, the rolling resistance of a tire has a great influence on the driving performance and fuel efficiency of a vehicle.

The biggest cause of tire rolling resistance is hysteresis loss in each part of the tire. In other words, when a tire rolls, each part of the tire (tread,
(sidewalls, etc.) undergo repeated deformation, and loss due to this repeated deformation, ie hysteresis loss, ultimately generates heat and increases the tire temperature.
Dissipated to the outside.

Therefore, reducing the hysteresis loss in the tire structure is most effective in reducing the rolling resistance of the tire.

Conventionally, in order to reduce hysteresis loss in tire structural parts, improvements have been made to the structure of the tread part, the tread pattern, the structure of the sidewall part, etc.

For example, if the rubber of the sidewall is thick, the sidewall on the contact side of the tire will be greatly deformed by the load (large curvature), and the rest of the sidewall will be restored by the air pressure filled ( Since the hysteresis loss is large when deformation (small curvature) is repeated, there is a method of reducing the thickness of the rubber of the sidewall in order to reduce the hysteresis loss.

[Problem to be solved by the invention] However, it is difficult to reduce the thickness of the rubber of the entire sidewall (
This poses a problem in that the cut resistance, which prevents the cord from breaking due to external impact, and the impact resistance, etc., deteriorate.

An object of the present invention is to solve the above problems and provide a low rolling resistance tire that reduces hysteresis loss and reduces the rolling resistance of the tire while ensuring the strength of the sidewall.

[Means for Solving the Problems] In order to achieve the above object, the low rolling resistance tire of the present invention is a tire having a tread formed in an annular shape and sidewalls extending from both ends of the tread. In the buttress part, which is the transition part with the wall,
A substantially continuous annular groove is provided in the circumferential direction concentric with the tread.

[Function] The low rolling resistance tire of the present invention configured as described above has a predetermined groove formed on the outer surface of the heartrest portion between the tread and the sidewall in the circumferential direction concentric with the tread, but not reaching the carcass. By providing an annular groove with a groove depth and groove width, the flexibility of the buttress part increases and the resistance to deformation decreases, so the number of repeated deformations due to bending and stretching movements of the buttress part due to tire rotation is reduced. Even if the tire is moved, the hysteresis loss generated in the buttress portion is reduced, stress concentration on the buttress portion is alleviated, and the rolling resistance of the tire can be reduced.

(Example〕 Embodiments of the present invention will be described based on the drawings.

In FIG. 1, a tire 1 includes a tread portion 2 formed in an annular shape, a sidewall 3 formed extending radially inward from both ends of the tread portion 20, and a bead portion formed at the inner peripheral end of the sidewall 3. 4, a bead wire 5 is embedded in the bead portion 4, and the bead portion 4 is attached and fixed to the rim.

A carcass 6 is disposed from the bead portions 4 on both sides to the sidewall 3 and the tread portion 2, and both ends of the carcass 6 are folded back around the bead wire 5 from the inside to the outside, and a bead apex 9 is attached to the folded portion of the carcass 6. A belt 7 is disposed in a ring shape on the outside of the carcass 6 within the tread portion 2.

On the side that is not in contact with the ground, the distance from the tire maximum width position of the sidewall 3 to the outer peripheral surface of the tread portion 2, that is, the tire maximum diameter part is defined as the tire upper section height H, and a predetermined distance h from the tire maximum width position. (However, h − (0,5±
0.05) The position of 0.05) H) is determined on the sidewall 3, and the tread is placed on the buttress part 8 between the position and the ground contact end E, which is the side end of the sidewall 3 side of the ground contact part of the tread part 2. An annular groove 9 having a predetermined depth that does not reach the carcass 6 is formed in the circumferential direction concentrically with the part 2.

In other words, the distance Rh = (0,5±
0.05) An annular groove 9 is provided in the buttress part 8 between the position H and the ground contact end E of the tread part 2, and the buttress part 8 is a part where distortion due to tire rotation is high. Therefore, by providing the annular groove 9 in the buttress part 8, the resistance to bending deformation of the buttress part 8 can be reduced, and hysteresis loss can be reduced, so that the rolling resistance of the tire can be reduced. be.

Furthermore, since the amount of rubber is reduced, the weight of the tire can be reduced, thereby reducing fuel consumption.

If h that defines the above-mentioned position is h<0.45H, the annular groove approaches the maximum width position where the bending of the sidewall is maximum, increasing the possibility of damage to the case.

On the other hand, if h>0.55H, the annular groove 9 provided in the bunttress portion 8 will be close to the ground contact edge E of the tread portion 2, reducing the rigidity of this portion, resulting in stable tire handling. make sex worse.

The groove depth t of the annular groove 9 is 1.0 mm or more and less than 3.0 mm (1.0≦t<3.0).

When the groove depth t is less than 1.0 mm, the effect of reducing the resistance to bending deformation in the buttress portion 8 is small, and the effect of reducing the rolling resistance of the tire is small.

Furthermore, if the groove depth t of the annular groove 9 is set to 3.0 mm or more, the rubber layer that protects the carcass 6 becomes too thin, which may damage the carcass 6 and reduce durability. do.

Furthermore, the groove width W of the annular groove 9 is a value of 5.0 mm or more and 10 − or more smaller than the distance llAs between the position and the ground contact edge E (5.
, 0≦W≦5-10).

If the groove width W of the annular groove 9 is 5.0 mm or less, the effect of reducing the resistance to bending deformation in the buttress portion 8 is small, and the effect of reducing the rolling resistance of the tire is small.

Also, the difference between the groove width W and the distance S between the position and the grounding edge E is 1
If it is less than 0 (was-10), the annular groove 9 will be close to the ground contact edge of the tread portion 2, which will reduce the rigidity of this portion, thereby deteriorating the steering stability of the tire.

Next, to describe the experimental results of tires to which the present invention was applied, the tires used were size 185, and the internal pressure was the normal internal pressure.
The load was 1.5 times the normal load and the speed was 60 km/h.

The table below shows the above experimental results.

Second, the RR effect is the effect of reducing rolling resistance (1?RC), and small means a reduction effect of less than 3%, and medium means a reduction effect of 3 to 5%.
% reduction effect, large indicates a reduction effect of 6% or more.

For example, the tire in example (■) has a groove depth of 1. om, an annular groove with a groove width of 10 mm is provided in the buttress part, and the weight is 30 mm.
g and can reduce rolling resistance by 3 to 5%.

Furthermore, since the tires of Examples (2) and (2) have poor durability, it is desirable that the groove depth of the annular groove is 3.0 m or less.

(Effects of the Invention) Since the present invention is configured as described above, it produces the effects described below.

By providing an annular groove on the outer surface of the buttress between the tread and the sidewall in the circumferential direction concentric with the tread with a predetermined groove depth and groove width that does not reach the carcass, the rubber of the buttress In addition to reducing the weight by reducing the weight, the flexibility of the buttress increases and the resistance to deformation decreases, so even if the buttress is repeatedly deformed due to bending and stretching movements associated with tire transfer, The hysteresis loss that occurs in the buttress is reduced, reducing stress concentration on the buttress and reducing the rolling resistance of the tire.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, with FIG. 1 being a sectional view and FIG. 2 being a side view. 3...Side wall, 6...Carcass, 8...
9. Annular groove. Patent applicant: Sumitomo Rubber Industries, Ltd.

Claims (1)

[Claims] (1) A tire having an annularly formed tread and sidewalls extending from both ends of the tread, the annular shape substantially continuous in the circumferential direction at the buttress portion which is the transition part from the tread to the sidewall. A low rolling resistance tire featuring grooves.