JPH03178810A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To make compatible the driving and braking quality with the improvement of the turning performance of an all-season pneumatic tire of a block base pattern having a calf on an iced road by specifying a distribution mean value and a ratio of a maximum value to a minimum value respectively in all directions for a ratio of the total projected length of the calf in a direction orthogonal with an active force direction and a total tread area. CONSTITUTION:A calf 5 is subjected to an active force F from a direction at an angle of alpha with a tire peripheral direction E-E'. In this case, the mean distribution value of a ratio SIGMALn(alpha)/S of a total SIGMALn(alpha) to a tread surface area S is set to 0.03 to 0.05mm<-1> when the angle alpha is changed by 0 to 360 degrees for all carves 5 of the projected length (alpha) in a direction orthogonal with the active force F. Also, a ratio of the minimum value of the distribution to the maximum value is specified to 0.5 or more. According to the aforesaid construction, driving and braking quality is maintained and a cornering performance can be improved on an iced road.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a dry air pump, and more specifically, an all-season air pump that improves cornering performance while maintaining driveability and braking performance on snowy roads. Regarding tires.

[Prior art]

So-called all-season tires designed to be used all year round generally adopt a block pattern in consideration of driving performance and braking performance on snowy roads in winter. The straight-line driving and braking performance of these all-season tires has improved significantly over the past few years, thanks to innovations such as the shape of the grooves forming the blocks and the way the kerfs are carved.

However, the reality is that no effective means has yet been found to improve performance during cornering, other than increasing the adhesive strength of the tread rubber.

[Problem to be solved by the invention]

In view of the above problems, an object of the present invention is to provide a pneumatic retirement tire that improves cornering performance while maintaining good driving performance and braking performance on snowy roads by devising a kerf provided on the block. It is about providing.

[Means to solve the problem]

In order to achieve the above object, the pneumatic tire according to the present invention has a block basic pattern in which a large number of blocks formed surrounded by grooves with a groove width of 1.5 nm or more are provided with kerfs with a groove width of less than 1.5 mm. The above-mentioned kerf within the tread contact area is set as follows.

In other words, the total amount ΣL of all the kerfs of the length of the kerfs provided on the blocks in the tread contact area projected in a direction perpendicular to the direction forming an angle α with respect to the tire circumferential direction.
Ratio of m1 (α) to the total tread surface area S ΣLn (α)
When /S is ρk(α), the average value of the distribution when the ratio ρk(α) is changed in the range of 0° to 360° is 0.03 to 0.05 mr'. and the ratio of the minimum value to the maximum value of the distribution is 0.5 or more.

By installing a block with such a kerf on the tire tread surface, it not only provides driving force and braking force when driving straight on snowy and icy roads, but also exerts the same frictional force in all directions when cornering. As a result, good cornering performance can be obtained.

Hereinafter, a description will be given using specific examples shown in the drawings.

FIG. 1 shows an example of a block pattern provided in the pneumatic tire of the present invention.

The tread surface 1 is provided with a plurality of grooves 2 in the tire circumferential direction E-E', and a plurality of grooves 3 extending in the width direction so as to intersect with these grooves 2. Both of these grooves 2 and 3 have a groove width of 1.5 mm or more. The block 4 is formed by being surrounded by these grooves 2 and 3, and has one or more kerfs 5 made of thin cuts with a groove width of less than 1.51 mm within its surface.

In such a block pattern, the kerf provided on the block within the contact area corresponding to the contact width W is a major factor in the generation of frictional force by the tire in a snowy waterway. In other words, among the many kerfs, the kerfs that face in a direction transverse to the force acting along the tread surface during driving engage with the road surface in a claw-like manner, abrade and destroy the road surface, and generate frictional force. occurs.

FIG. 2 diagrammatically explains the kerf that generates frictional force as described above.

As shown in FIG. 2, when the tire is cornering, for example, the block 4 arranged at a part of the center of the tread pattern in FIG. When receiving the acting force F, the kerf 5 provided across the direction of the acting force generates a drag force as a frictional force. This frictional force is caused by the length L (
In the case of the block shown, since there are two kerfs, the length, (α) and Lx
The sum of (α) is a function of the drag force (frictional force). Therefore, if there are n kerfs on the entire tread surface, the sum of the lengths projected onto the line segment K is ΣLm(α). can be expressed.

In the present invention, the function ΣLm(α) of the frictional force generated by the kerf in the block is expressed as the ratio ρk(α) to the total tread surface area S (=tread contact width W×tire circumference P).
This ratio ρ(α) is expressed as 360 from the angle α=O°
In the distribution when changed to ”, its ρ α)
The average value of is 0.03~0. O5mm-' range, more preferably 0.03 to 0.045+u+-', and the ratio of the minimum value to the maximum value of ρk(α) is 0.
．． It should be 5 or more.

As shown in the graph of FIG. 3, the average value of the distribution of ρk(α) is 0. If it is smaller than O3 mm-', the maneuverability and stability performance on dry roads in summer will be improved, but the cornering performance on snowy and icy roads in winter will be lower than the allowable limit. Also, the above average value is 0.05 nuw-'
If it is larger than , on the contrary, cornering performance on snowy roads in winter will improve, but maneuverability and stability performance on dry roads in summer will fall below the allowable limit.

Therefore, the average value is 0.03 to 0. By setting it in the range of 05 mm-', it is possible to obtain an excellent all-season tire that balances maneuverability and stability performance on dry roads and cornering performance on snowy roads. For comparison, FIG. 3 shows the average values of ρk(α) in commercially available summer tires exclusively for summer and winter tires exclusively for winter.

In addition, in the distribution of ρk(α) when the angle α is changed from 01 to 360', by setting the ratio of the minimum value to the maximum value to be 0.5 or more, it is possible to As a result, frictional force is exerted against the vehicle, resulting in excellent cornering performance as shown in Fig. 4. Furthermore, wear resistance performance can also be improved. As shown in the graph of Figure 4, the above ρk based on the kerf of a conventional all-season tire
The ratio of the minimum value to the maximum value of (α) is only 0.48 at most, and the cornering performance and wear resistance performance on snowy and icy roads are both poor.

Although the distribution of the edge effect based on the kerf has been described above, cornering characteristics can be further improved if the edges formed around the block in the present invention are made to have the same distribution as the kerf.

In the case of this block edge, as illustrated and explained in FIG. 6 and FIG. It is necessary to calculate the above function for the edge portion that contributes to generation.

That is, as shown in FIG. 6, when the tire is cornering, the block 4 disposed, for example, in a part of the center of the tread pattern in FIG.
When an acting force F is applied from a direction forming an angle α to ',
Edge portion 4 on the leading edge side facing in a direction transverse to its direction of action
e is generated as a drag force as a friction force. This frictional force is applied to the edge portion 4e by a line segment K in a direction perpendicular to the direction of the angle α.
It can be expressed as a function of the length EL(α) projected onto .

In addition, when the block 4 has a lateral groove 3 internally, such as the block 4 disposed in a part of the shoulder of the tread pattern in FIG. 1, as shown in FIG. 7, two edge portions 48+, 48g generates a drag force (frictional force) against the external force F. Therefore, these two edge parts 4 e
+ + 4 e The sum of the lengths ELI (α) and EL2 (α), which are projected onto the above line segment K, is the drag force (frictional force)
becomes a function of

In this way, the outline of the block is complicatedly curved,
Alternatively, the number of edge portions that generate resistance against external force due to internal lateral grooves can be any number n, so the total length of these projected onto line segment K is ΣEL, 1
(α).

The frictional force function ΣEL, (α) generated by the edge portion of such a block is expressed as the ratio ρ9(α) to the total tread surface area S (=tread contact width W x tire circumference P), as in the case of the kerf. Expressing (ρ9(α)=ΣEL,
(α)/S), the frictional force due to the edge portion of this block is calculated by converting the above ratio ρg(α) from the angle α=0° to 36
The average value of the distribution when changing to 0° is 0.035 ~
in the range of 0.05 mn+-', more preferably 0.03
It is desirable to set it in the range of 5 to 0.045 mm-'.

Also, the ratio of the minimum value to the maximum value of ρk(α) is 0.7
It is desirable that the value is more preferably 0.75 or more.

FIG. 5 shows the above ρk(α ) shows the distribution when changing the value of angle α from 0″ to 360＠.

The distribution of ρk(α) for the block pattern kerf in this example tire has a maximum value of ρ5 as shown in the figure.
．． □8 is 0.042 mm-' Minimum pH+@11
11 is 0.022 mm-', and the average value of the distribution is 0.034 mm-'. That is, 0, 03 to 0.0 as defined by the present invention. It is within the range of O5mm-'. Also, the ratio ρ of the minimum value to the maximum value is +1jlR/c1. X is 0.52, which is in the range of 0.5 or more defined by the present invention.

Since this example tire has an average value of ρk(α> of 0.034 mm-', it has excellent cornering performance on snowy water during cornering on snowy and icy roads in winter,
It can demonstrate a well-balanced control and stability performance during cornering on dry roads in the summer. Furthermore, since the ratio of the minimum value to the maximum value is 0.52, the frictional force is exerted evenly in all directions, as is clear at a glance from FIG.

On the other hand, Fig. 8 shows the distribution when the value of ρg(α) mentioned above regarding the edge of the block is changed from the angle α=O＠ to 360＠ for the same all-season tire having the characteristics shown in Fig. 5. It is something that

As shown in the figure, the distribution of ρk(α) of this tire has a maximum value of ρ9. ．． □ is 0.039 nus-', minimum value (' 9
+ 1111 r 11 is 0.031 nu++-'
The average value of the distribution 4° is 0.036 mc'. That is, 0.035 to 0.090, which is suitable for the block edge described above.
It is within the range of 5iI11-'. Also, the ratio of the minimum value to the maximum value ρg, mAn/ρ9. □8 is 0.
795, which is also in the range of 0.7 or more, which is also suitable for block edges.

〔Effect of the invention〕

As described above, the pneumatic tire of the present invention can exert frictional force in the same way in all directions by devising the arrangement of the block kerfs in the block pattern. Therefore, good driveability and
It is possible to maintain braking performance and improve cornering performance not only on dry roads but also on snowy roads.

[Brief explanation of drawings]

Fig. 1 is a plan view showing an example of the 1-red pattern of the pneumatic tire according to the present invention, Fig. 2 is an explanatory diagram illustrating the generation of drag C7 by the kerf provided on the block, and Fig. 3
The figure shows the relationship between the average value of p(α) and the steering/stability performance on dry roads as well as the cornering performance on snowy and icy roads. A diagram of the relationship between cornering performance and wear resistance performance, Figure 5 is a distribution diagram of α (α) of the example tire of the present invention, and Figures 6 and 7 correspond to Figure 2 showing the case of block edge. Explanatory diagram,
FIG. 8 is a distribution diagram of ρk(α) based on the block edge of the same tire as FIG. 5. 1... Tread surface, 2, 3... Groove, 4... Block, 5... Kerf.

Claims (1)

[Claims] In a pneumatic tire having a block-based pattern in which a kerf with a groove width of less than 1.5 mm is provided in a large number of blocks surrounded by grooves with a groove width of 1.5 mm or more, the kerf in the tread contact area is attached to the tire. Angle α to the circumferential direction
The total amount ΣL_n(α) of all the kerfs of the length projected in the direction perpendicular to the direction of , and the total tread surface area S
When the ratio ΣL_m(α)/S is ρ_k(α),
The average value of the distribution of the ratio ρ_k(α) when the angle α is changed in the range of 0° to 360° is 0.03 to 0.05 m.
A pneumatic tire having a range of m^-^1 and a ratio of the minimum value to the maximum value of the distribution of 0.5 or more.