JPS6361608A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To decrease noises by making variably pitch numbers of blocks of shoulder parts to be smaller than that of center parts in tires in which blocks are formed with main grooves and sub grooves. CONSTITUTION:Many ribs a-c are formed with main grooves 2 and many blocks 4a-4c are formed by a crossing of sub grooves 3 to each rib a-c. And in this case, pitches of blocks 4a-4c formed at each rib a-c are changed variably, and blocks are arranged independently for each rib a-c well as blocks having a different pitch for each rib a-c are arranged at random. Also, pitch numbers N for each rib are decreased gradually so that center part ribs a are the largest and shoulder part ribs c are the smallest. This constitution enables low noises.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a pneumatic tire with reduced noise generation.

[Prior art]

Conventionally, methods for reducing noise from pneumatic tires have been to variably change the pitch of a large number of blocks arranged around the tire circumference, and to reduce the noise generated by variably changing the pitch of a large number of blocks arranged around the tire circumference, and arranging a fixed number of blocks around the tire circumference as a repeating unit. It has become common to aim for the dispersion of When applying such a variable pitch arrangement to a pneumatic tire based on a rib configuration with multiple main grooves on the tire circumference, the basic pitch arrangement for each rib is shown in Figure 4. Generally, the same variable pitch arrangement was arranged.

However, with such conventional pneumatic tires, the pattern noise generated during transfer concentrates in the same frequency band for each rib, resulting in the problem that the peak values (sound pressure levels) of the noise overlap and become large. there were. For this reason, conventional methods have limited noise dispersion effects.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a pneumatic tire that can reduce noise in the negative layer.

[Structure of the invention]

The pneumatic tire of the present invention for achieving the above object includes:
In a tread pattern in which a tire has a plurality of main grooves in the circumferential direction, and a large number of blocks are formed in ribs separated by these main grooves and sub-grooves that cross the ribs, the pitch of the blocks formed in each rib is It is characterized in that it is made variable, and the variable pitch arrangement is made different for each rib, and the number of pinches is smaller in the ribs located in the shoulder part than in the ribs in the center part.

Hereinafter, details will be explained based on the embodiment shown in the figures.

FIG. 1 shows a tread of a pneumatic tire according to an embodiment of the present invention. This tread 1 has multiple main grooves 2.
．． -., 2 are provided along the tire circumferential direction, and these main grooves 2. A large number of ribs are formed which are divided into -. and 2. Among these ribs, the center rib a, the center rib b, and the shoulder rib C have a large number of sub-grooves 3. ...-23 is provided,
A number of blocks 4a, - in each.

4a; 4b, =-, 4b; 4c, .-, 4c are formed.

Blocks 4a formed on each rib a, b, c.

4b and 4c are formed so that the pitch (circumferential length per block) can vary. That is, blocks with long pitch A, intermediate length pitch B
blocks, blocks with a short pitch C, etc. are arranged in a randomly mixed state. Of course, the pitches are not limited to only three types like A, B, and C, but may be a mixture of four or more types. Further, under such conditions where blocks with different pitches coexist, it is preferable that the ratio R between the maximum pitch (longest) and the minimum pitch (shortest) differ for each rib.

For example, the maximum to minimum pitch ratio R in rib a is 1.6
In contrast, it is 1.5 for rib b and 1.3 for rib C.
It is to do so.

Moreover, in the present invention, this variable pitch arrangement is made to vary independently and differently for each of the ribs a, b, and c. That is, rib a is, for example, BAABCC
, rib b has another different arrangement of CBABCC, and rib C has a further different arrangement of CBABCC.
The array is AABBCC.

Further, in the present invention, the number N of pitches per rib is the largest in the rib a at the center portion, and decreases toward the rib C at the shoulder portion.

In other words, the above relationship is expressed in a table as follows.

On the other hand, in the conventional pneumatic tire shown in Fig. 4,
As a noise reduction method, the pitch arrangement of the block is made variable, but there is no change between each rib a, b, and c, and the same variable pitch arrangement BAABBCCC
It has become BA...

Therefore, the pitch number N and the ratio R of maximum and minimum pitches are the same between each rib. That is, as shown in the table below.

In the case of Fig. 4, the pitch arrangement per rib is variable, so the noise frequency is dispersed.
A reduction in noise can be expected.

However, since the number of pitches between adjacent ribs is the same and does not change, the maximum value of the pattern noise generated by tire rotation is concentrated at the same time, resulting in an increase in the sound pressure level. It has become.

On the other hand, in the case of the present invention shown in FIG. 1, the variable pitch arrangement is different for each rib. Therefore, the maximum value of the noise pattern generated when the tire rotates is dispersed and does not concentrate at the same time, so the sound pressure level is reduced, and it is possible to reduce the noise in the negative layer.

Furthermore, in the present invention, since the number of pitches in each rib is smaller as the ribs in the shoulder area become smaller, the block rigidity in the shoulder area does not decrease, thereby reducing the driving performance of the vehicle, especially the steering stability. It has the advantage of being highly maintainable.

FIGS. 2 and 3 show other embodiments of the present invention, respectively. In these embodiments, the number of ribs is one more than in the case of FIG. In other words, a third rib b'' is provided in which a large number of blocks 4b'' are arranged.Furthermore, in the case of Fig. 2, the different pitch types are not only A, B, and C, but also D and E. They are distributed into five types.

If the pitch arrangement relationships in the embodiments shown in FIGS. 2 and 3 are tabulated in the same way as in the above embodiments, in the case of FIG. 2, and in the case of FIG. 3, it is as follows.

In either case, as in the embodiment shown in Fig. 1, the variable pitch arrangement is different for each rib, thereby dispersing the maximum value of the noise pattern generated during tire rotation and concentrating it at the same time. Since there is no noise, the sound pressure level can be lowered. In addition, since the number of pitches of the ribs is smaller in the shoulder portion, the block rigidity of the shoulder portion is not reduced (thereby, the driving performance of the vehicle is not deteriorated).

〔Effect of the invention〕

As mentioned above, in the pneumatic tire of the present invention, the pitch of the blocks formed on each rib is made variable, and the variable pitch arrangement is made different for each rib. Since the maximum values of the noise patterns are dispersed and are not concentrated at the same time, the sound pressure level can be lowered, thereby making it possible to reduce the noise in the negative layer.

In addition, since the number of pitches of the ribs located in the shoulder part is smaller than that of the ribs in the center part, the block rigidity of the shoulder part does not decrease, thereby reducing the driving performance of the vehicle, especially the handling stability. do not have.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a main part of a tread of a pneumatic tire according to an embodiment of the present invention, FIGS. 2 and 3 are plan views showing main parts of a tread according to other embodiments, and FIG. FIG. 3 is a plan view of the main part of the pneumatic tread. 1... Tread, 2... Main groove, 3... Minor groove,
4a, 4b, 4b', 4c - block, a. b, b', c...rib.

Claims (1)

[Claims] In a tread pattern in which a tire has a plurality of main grooves in the circumferential direction, and a large number of blocks are formed in ribs separated by these main grooves and sub-grooves that cross the ribs, the pitch of the blocks formed in each rib is This pneumatic tire is made variable, and the variable pitch arrangement is different for each rib, and the number of pitches is smaller in the ribs located in the shoulder part than in the center part.