JPH09175107A - Pneumatic bias tire for motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic bias tire for a motorcycle which can improve straight advancing stability by increasing transverse rigidity without excessively improving rigidity in a side wall part and without impeding productivity. SOLUTION: A tire comprises a tread part 1, pair of side wall parts 2 and a pair of bead parts 3, the tire has two sheets of carcasses 4, 5 reinforcing over mutually between bead cores 6 burying each of these parts in the bead part 3 and one or two sheets or more of barkers 7 protectively reinforcing the tread part in the periphery of this carcass, a chord angle of the carcass is provided between 25 to 65 deg. relating to the tire peripheral direction, a chord angle of the breaker 7 in the outermost layer is set to between 70 to 90 deg. relating to the tire peripheral direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic bias tire for a motor cycle intended to improve straight running stability.

[0002]

2. Description of the Related Art Improving straight running stability is one of means for improving tire performance. It is known that increasing the lateral rigidity is effective for improving the straight running stability. That is, when the tire rolls over the protrusion on the road surface when the tire rolls, the tire tread may be deformed laterally depending on the position of the protrusion, resulting in wobbling of the steering wheel, etc.However, if lateral rigidity is insufficient, the lateral direction of the tire tread Deformation cannot be suppressed, resulting in impaired steering stability during straight running. If you increase the lateral rigidity,
Lateral deformation of the tire tread can be suppressed, and steering stability when traveling straight ahead is improved. BACKGROUND ART In pneumatic tires for four-wheeled vehicles such as passenger cars, it has been widely practiced to provide a reinforcing layer such as a hard rubber layer in the side wall portion of the tire as a means for increasing the lateral rigidity.

[0003]

However, when the above-mentioned improving means is applied to a pneumatic bias tire for a motor cycle, the rigidity of the side wall portion is excessively improved, resulting in the steering stability during turning. There are disadvantages such as deterioration of In addition, the provision of a new reinforcing layer leads to an increase in the number of members, which is a factor that hinders productivity.

The present invention has been made in view of the above circumstances, and the rigidity of the side wall portion does not increase too much.
Another object of the present invention is to provide a pneumatic bias tire for a motor cycle, which can improve lateral rigidity and improve straight running stability without impeding productivity.

[0005]

Therefore, as described in claim 1, the present invention comprises a tread portion, a pair of side wall portions, and a pair of bead portions, each of which is a bead. Each of the carcass includes two carcass embedded in the bead portion to reinforce each other between the bead cores and one breaker for protecting and strengthening the tread portion on the outer periphery of the carcass. In the pneumatic bias tire for motor cycle, the code angle of the breaker is between 25 ° and 65 ° with respect to the tire circumferential direction. The code angle of the breaker is 70 ° with respect to the tire circumferential direction. The configuration is set between 90 degrees.

According to the present invention, by arranging the code angle of the breaker substantially directly to the traveling direction of the tire, a triangular structure is formed between the breaker and the two carcasses. It is possible to improve the lateral rigidity as compared with the conventional bias structure (structure in which the code angle of the breaker is almost the same as or close to the code angle of the two-layer carcass). it can.
This increase in lateral rigidity was very slight when the code angle of the breaker was less than 70 degrees.

If two or more breakers are provided,
According to a second aspect of the invention, the code angle of the outermost breaker is set between 70 ° and 90 ° with respect to the tire circumferential direction. As the outermost layer, the lateral rigidity was remarkably increased when the code angle of the breaker of the outermost layer was 70 to 90 degrees with respect to the tire circumferential direction, but other than the outermost layer. Blur
When the car was set to 70 to 90 degrees with respect to the tire circumferential direction, the lateral rigidity was slightly increased. The reason why the rate of increase in lateral rigidity is remarkable in the case of the outermost layer is that when the breaker of the outermost layer is set to 70 to 90 degrees, the breaker adjacent to the tread rubber takes the lateral tension. It is considered that the effect of the outermost layer breaker suppressing the lateral deformation of the tread appears in addition to the effect of the triangular structure.

Further, as described in claim 3, in the case of one breaker, it is provided at both ends between the breaker and the adjacent carcass, and in the case of a plurality of breakers, this is It is desirable to interpose rubber layers at both ends between adjacent breakers. Since a large angle difference (maximum of 65 degrees) is formed between the breaker and the breaker or the carcass adjacent to the breaker, this large angle difference causes an interlayer difference near the end portion during tire rolling. It will cause distortion. Therefore, by interposing the rubber layer, the interlayer strain in the vicinity of the end portion is alleviated, and the occurrence of separation due to the interlayer strain is prevented. In particular, in the case of a motor cycle tire, it is effective because a large interlayer strain is generated during cornering traveling by a large camber.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, reference numeral 1 is a tread portion, reference numeral 2 is a pair of side wall portions, and reference numeral 3 is a pair of bead portions. The two carcasses consist of a first carcass ply 4 and a second carcass ply 5, and the side wall part 2 extends between the bead cores 6 embedded in the bead part 3.
And the tread portion 1 are reinforced. One breaker 7 protects and strengthens the tread portion 1 on the outer circumferences of the first and second carcass plies 4 and 5.

The first and second carcass plies 4 and 5 reinforce the side wall portion 2 and the tread portion 1 as a main body portion 4.
a and 5a and folded-back portions 4b and 5b that wind up around the bead core 6 respectively. The first and second carcass plies 4 and 5 are made of a rubber cloth of a bias cross array organic fiber cord, and the cord angle of each carcass ply is between 25 ° and 65 ° with respect to the tire circumferential direction. It is in.

The breaker 7 is a bias array organic fiber core.
The rubberized cloth of the cord is suitable, and the code angle of the breaker 7 is between 70 ° and 90 ° with respect to the tire circumferential direction. The breaker 7 is one in the example of FIG. 1, but in the case of a plurality of breakers, the code angle of the outermost breaker is between 70 ° and 90 ° with respect to the tire circumferential direction.

[0012]

EXAMPLES Examples 1 and 2 are bias tires for a motor cycle, the size is 140 / 70-17, the configuration is in accordance with FIG. 1, and the carcass is a bias crossover array 1260D.
It consists of 2 plies of / 2 nylon cord, and the breaker consists of 1 sheet of 1260D / 2 nylon cord. The bias tire of Example 1 includes the first and second carcass plies 4,
The code angle of No. 5 is a bias crossing arrangement which makes 30 degrees with respect to the tire circumferential direction, and the code angle of the breaker 7 is 90 degrees with respect to the tire circumferential direction. The bias tire of Example 2 has the same structure as that of Example 1, except that the code angle of the breaker 7 is 80 degrees with respect to the tire circumferential direction. The bias tire of the comparative example is a breaker tire.
The structure is the same as in Examples 1 and 2, except that the angle of the tire is 30 degrees, which is the same as the carcass ply with respect to the tire circumferential direction.

The tires of Examples 1 and 2 and the comparative example were molded.
The tires were mounted on the front wheels of a motorcycle and run on a test course by an experienced test driver to carry out a comparative test of straight running stability as one of tire dynamic performances. The evaluation result is represented by an index with Comparative Example being 100, and the larger the value, the better. The results were 115 in Example 1 and 105 in Example 2 with Comparative Example being 100. From these evaluation results, the straight running stability of the comparative example tires and the example tires are improved, and the straight running stability is more significantly improved as the angle of the breaker approaches 90 degrees with respect to the tire circumferential direction. I found out.

[0014]

According to the present invention, the rigidity of the side wall portion is not excessively improved, the productivity is not hindered without increasing the number of members, and the lateral rigidity is increased to improve the straight running stability. It is possible to obtain a pneumatic bias tire for a motor cycle capable of improving the above.

[Brief description of the drawings]

FIG. 1 is a sectional view of a pneumatic bias tire for a motor cycle according to the present invention.

[Explanation of symbols]

 1 tread part 2 side wall part 3 bead part 4 first carcass ply 5 second carcass ply 6 bead core 7 breaker.

Claims (3)

[Claims] 1. A card comprising a tread portion, a pair of side wall portions, and a pair of bead portions, each of which is reinforced between the bead cores embedded in the bead portion. The carcass includes a scrap and one breaker for protecting and strengthening the tread portion on the outer circumference of the carcass, and the code angle of each carcass is between 25 ° and 65 ° with respect to the tire circumferential direction. The pneumatic bias tire for a motor cycle according to claim 1, wherein the breaker has a code angle of 70 to 90 degrees with respect to the tire circumferential direction. Pneumatic bias tire. 2. A tread portion, a pair of side wall portions, and a pair of bead portions, each of which is reinforced between two bead cores embedded in the bead portion. The carcass is provided with two or more breakers for protecting and strengthening the tread portion on the outer circumference of the carcass. The code angle of each carcass is 25 to 65 degrees with respect to the tire circumferential direction. In a pneumatic bias tire for a motor cycle in between, the code angle of the outermost breaker is between 70 ° and 90 ° with respect to the tire circumferential direction.
Pneumatic bias tire for tar cycle. 3. An end portion between the one breaker and a carcass adjacent thereto, or between the outermost breaker and a breaker adjacent thereto. The pneumatic bias tire for a motor cycle according to claim 1 or 2, wherein rubber layers are provided at both ends.