JP3088775B2 - Racing tires - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a racing tire mainly used under intermediate use conditions of an automobile race.

[0002]

2. Description of the Related Art Racing tires used for ultra-high-speed running require a hard or soft tread rubber to be used in accordance with a change in use conditions due to the environment such as climate and temperature. Then, if you select the software, heat dripping will occur during the race, causing blowdown and performance degradation. Also, if you select hard,
Lap time is poor because the initial grip is poor and it takes time for the rubber to reach a suitable temperature.

[0003] Conventionally, Japanese Patent Laid-Open No.
As disclosed in US Pat.
Formed in a layered structure, the cap rubber layer is made of soft compound rubber, and the base rubber layer is made of hard compound rubber to improve the initial grip under intermediate use conditions and prevent heat sagging during the race Racing tires have been proposed.

[0004]

However, even in this prior art, only the hard compound rubber is in contact with the ground during the race, and when the load is light and the heat generation is low, such as when driving straight, the optimum grip force and It has become difficult to get traction. Therefore, it is conceivable to make the base rubber layer slightly softer.However, the racing vehicle has a negative camber, the load point changes between straight running and cornering, and the heat generation of the tire also decreases in the tire axial side. Unlike the (iN) and the tire outer and (OUT), subjected to several times the load during straight during cornering in the tire outer side, to become a high temperature due to friction, when using the same soft compound rubber and machine body , Heat sagging and the like.

[0005] The present invention divides the base rubber layer in the tire axial direction, the inboard soft compound rubber, the outer Ha
By forming respectively over de compounding rubber,
It is an object of the present invention to provide a racing tire capable of solving the problems of the related art.

[0006]

Means for solving the problems in the present invention are as follows. A tread 2 outside the tire diameter of the carcass 1 is provided with a base rubber layer 3 on the carcass 1 side and a tire formed from the base rubber layer 3. Located outside diameter and JISA hard
And a cap rubber layer 4 which is formed by the soft compound rubber in degrees 30-60 degrees, the base rubber layer 3
Is divided in the tire axial direction, and the fuselage-side divided layer 3A is capped
By forming the outer division layer 3B with a harder compound rubber than the fuselage-side division layer 3A and the cap rubber layer 4, the outer division layer 3B is made of a soft compound rubber having the same or the JISA hardness of 40 to 70 degrees as the rubber layer 4. is there.

[0007]

In the early stage of the race under intermediate use conditions, the cap rubber layer 4 made of the soft compound rubber of the tread 2 becomes an appropriate temperature in a short time to obtain an optimum grip force and traction, thereby improving the lap time. After the initial stage of the race, the tires are heated by friction, and the cap rubber layer 4 disappears and the base rubber layer 3
Is exposed. In the middle of a race, the soft compound rubber fuselage side split layer 3A mainly works during straight running to obtain the optimal grip force even when the temperature does not become high. During cornering, the hard compound rubber outer split layer 3B mainly works, Optimum grip force and traction are obtained without blowdown even if

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In the embodiment shown in FIG. 1, the racing tire T is a tubeless tire having no inner liner and is attached to the rim 5. A tread 2 having a thickness of 1/2 to 1/3 of that of a normal tire is formed outside the tire diameter of the carcass 1, and the tread 2 is composed of a base rubber layer 3 on the carcass 1 side and a tire formed from the base rubber layer 3 And a cap rubber layer 4 located on the radially outer side.

The cap rubber layer 4 is made of, for example, a soft compound rubber having a JISA hardness of 30 to 60 degrees and has a thickness of about 1 to 2 mm. The base rubber layer 3
Is divided into two in the tire axial direction into a divided layer 3A on the fuselage side when mounted on the fuselage and a divided layer 3B on the outside, and the fuselage-side divided layer 3A is formed of soft compound rubber, The outer divided layer 3B is formed of a hard compound rubber. The fuselage-side divided layer 3A is made of, for example, JISA
The outer divided layer 3B is formed of, for example, a hard compound rubber having a JISA hardness of 50 to 90 degrees higher than the fuselage-side divided layer 3A, and the outer divided layer 3B is formed of a soft compound rubber having a hardness of 40 to 70 degrees. The 3A soft compound rubber may be the same as or slightly harder than the cap rubber layer 4.

In the present invention, the difference between the hard and soft compounds of the hard compound rubber and the soft compound rubber is determined not only by the difference in the hardness of the rubber but also by the difference in the grip level and the difference in the speed of heat generation. Soft compound rubber with high level and high heat generation is used as soft compound rubber.Grip level at relatively low temperature is low, and heat compound is slow and hard to blow down even with heat is used as hard compound rubber.Grip level depends on driver's feeling. Things. The joining surface S between the fuselage-side divided layer 3A and the outer divided layer 3B is abutted on an inclined surface, and a part of the outer divided layer 3B is overlapped and joined to the outer peripheral side of the fuselage-side divided layer 3A. On the other hand, in the modification shown in FIG. 2, the joining state of the two divided layers 3A and 3B is reversed, and a part of the fuselage-side divided layer 3A is overlapped and joined to the outer peripheral side of the outer divided layer 3B. I have.

Which one of the divided layers is on the outer peripheral side on the bonding surface S depends on the use conditions. However, in both cases, the surface is longer and the bonding strength is higher than when the bonding surface S is vertical. And the wear becomes smooth. FIGS. 3 and 4 show the load change during the race. As shown in FIG.
Since the left and right tires have a tire shape inclined in a C-shape due to a negative camber, the base rubber layer 3 is mainly operated by the fuselage-side divided layer 3A of soft compound rubber,
Generates strong grip even with low heat generation.

At the time of cornering, as shown in FIG. 4, the right and left tires assume a tire posture in which the upper sides are inclined outward due to the centrifugal force of the fuselage. The layer moves to the layer 3B and becomes high in temperature due to friction. Since the outer divided layer 3B is made of hard compound rubber, it runs optimally without heat dripping even at high temperature. The graph of FIG. 5 shows the results of a running test of a conventional one-layer tread tire for intermediate use conditions and the tire of the present invention. The tread 2 has a rubber hardness of JI
When the SA hardness is 80 degrees and the cap rubber layer 4 of the present invention is JIS
A hardness 40 degrees, the fuselage side divided layer 3A has JISA hardness 50
The outer divided layer 3B has a JISA hardness of 80 degrees.

According to this graph, both tires record the same maximum lap time when the number of laps is 5 or 6 times, but the tire of the present invention has a faster initial rise and maintains a good lap time from the middle to late stages. You can see that it is doing.

[0014]

According to the present invention described above in detail, in a race under intermediate use conditions, the initial grip is improved, and the load during straight running and the like is light and the heat generation is low from the middle to late stages of the race. Occasionally, the soft compound rubber of the fuselage-side divided layer 3A can provide the optimum gripping force and traction, and even if a heavy load is applied during cornering and the temperature becomes high, the hard compound rubber of the outer divided layer 3B reduces heat sagging. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing a modification of the present invention.

FIG. 3 is an explanatory diagram showing a tire posture during straight running.

FIG. 4 is an explanatory diagram showing a tire posture during cornering.

FIG. 5 is a graph comparing the lap times of the present invention and the prior art.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 carcass 2 tread 3 base rubber layer 4 cap rubber layer 3A fuselage side divided layer 3B outer divided layer T tire

Claims (1)

(57) [Claims] 1. A base rubber layer (3) on the carcass (1) side on a tread (2) outside the tire diameter of the carcass (1).
When equipped with the the base rubber layer (3) than located on the tire radially outward and JISA hardness of 30 to 60 degrees cap rubber layer formed of a soft compound rubber (4),
The base rubber layer (3) is divided in the tire axial direction, and the fuselage-side divided layer (3A ) is the same as the cap rubber layer (4) or
For racing, formed by soft compound rubber having a JISA hardness of 40 to 70 degrees, and the outer division layer (3B) is formed by a compound rubber harder than the body-side division layer (3A) and the cap rubber layer (4). tire.