JP3365702B2 - Pneumatic tire with lugs - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire with a rug, and more particularly to a pneumatic tire with a lug that can be used for both wet field (paddy) work and upland work.

[0002]

2. Description of the Related Art Conventionally, pneumatic tires for cultivated land have lugs with a large number of C-shaped lugs arranged on the tread surface in order to ensure running performance when running on muddy or soft ground. The pattern is used. Especially for agricultural products, high rug patterns with high rugs were the mainstream because domestically, paddy field work is central. In Japan, the shift from agricultural cultivation to upland cultivation has recently been increasing due to the change of agricultural policy, and the case where both paddy field work and field work are commonly used has become the mainstream.

However, since the conventional pneumatic tire with lugs having a high lug pattern is manufactured mainly considering paddy field work, it exhibits excellent traction.
Not only in the paddy field but also in the field work, the soil is dug up to deepen the plow, and the field is damaged. Also, in the field work, when running a tractor etc. along the ridges, the width of the tire sidewall is used as a guide along the ridges, but conventional pneumatic tires with lugs are used as a guide. Since the tread width is set to be wider than the width of the tire side wall, there is a drawback that the ridge is broken by the lug that exceeds the side wall width.

Therefore, Japanese Utility Model Publication No. 3-35601 (conventional example 1), Japanese Examined Patent Publication No. 61-59921 (conventional example 2), JP-A-6-156018 and 7-232.
There is a technique disclosed in Japanese Patent No. 516 (conventional example 3).

[0005]

In the conventional example 1, the step surface where the rug thickness rapidly increases from the middle of the rug thickness gradually increasing area toward the root of the rug is provided with a front surface (stepping side) and a back surface (raising side) of the lug. )
Although it has at least one side of it, it is recognized that it has some usefulness, but since the inclination (rising angle) of the lug rising surface on the stepping side is not taken into consideration, mud is likely to adhere to the step part and it becomes slippery There was a problem of impairing traction. In the conventional example 2, the block width is widened as a whole by changing the inclination angle of both the step surface and the kick surface of the side wall of the lug for the purpose of reducing the wear of the lug. There is a problem that the circumferential clearance in the center of the tread portion of the rug is too narrow, causing mud clogging and slipping easily, and that the total volume of the lug is large and the tire is heavy and the price and fuel consumption are high. there were.

[0006] The conventional example 3 is intended to be commonly used with paddy fields and upland fields by setting the angle of the rug's stepping sidewall on a cross section parallel to the equatorial plane of the tire. Since the (average angle) was a uniform inclination angle with respect to the extending direction of the lug (the central portion that comes into contact with the ground first and the side end portion that comes into contact with the ground later), it was a step forward in terms of traction and slip ratio. The present invention relates to the above-mentioned conventional examples 1 to 1.
A pneumatic tire with lugs intended to solve the problem of No. 3 is provided.

[0007]

SUMMARY OF THE INVENTION According to the present invention, a pair of left and right sidewalls 1, a crown portion 2 which is continuous from both sidewalls 1 and extends between the sidewalls 1, and a shoulder portion from the center portion to the crown portion 2. A tread 5 in which a lug 4 extending obliquely with respect to the circumferential direction toward the portion 3 is projected in a V shape and arranged in the circumferential direction, and the center end of the crown portion of the lug 4 comes into contact with the ground first. In the pneumatic tire T with a lug in which the shoulder end of the lug 4 comes into contact with the ground later, the following technical measures are taken to achieve the above-mentioned object.

That is, according to the present invention, the stepping side walls 7 and 8 of the lugs 4 arranged in a V shape are the first side walls 7 which are steeply raised on the side to be grounded first, and are grounded later. The side is defined as a second side wall 8 that rises more loosely than the first side wall 7, and the kick surface side wall 9 of the lug 4 is the first side wall 8.
2 It is formed so as to rise steeply from the side walls 7 and 8,
In the lugs 4 arranged in a V shape, one or both of the first and second side walls 78 are steeply raised at the root side a on the root side in the lug cross section, and the lugs 4 extend from the bent portion 4B.
The tip b on the tip side is formed in a two-step bent cross section that rises gently.
And it is characterized in that they are.

In this case, since the first side wall 7 to be grounded first rises steeply, the bite to the ground is good regardless of whether it is a paddy field or a field, while the second side wall 8 to be grounded later is good. Is raised more gently than the first side wall 7,
Excessive disturbance on the ground is eliminated regardless of whether it is a paddy field or a field, and slip is suppressed here while sufficiently exerting traction (claim 1). Further, in the present invention, with respect to the lugs 4 arranged in a V shape, one or both of the first and second side walls 78 are located at the root side in the lug cross section.
The root part a rises sharply and rises from the bent part 4B to the tip side.
The front end b of the
The loosely rising tip b is the first tip on the root side.
The second tip portion bb on the tip side from the bent portion 4B with respect to the portion ba
Is gently erected and is formed into a cross section of two or more steps . With such a structure, the bite to the ground is further increased and the pavement is paved. When traveling on a road or farm road, vibration is suppressed (claim 2).

Further, in the present invention, the lugs 4 arranged in a V-shape are arranged on the side of the first side wall 7 of the tire equator line 0-0.
On the other hand, at a steep angle, the second side wall 8 side is made a gentle angle with respect to the tire equator line 0-0, and it can be folded in two in the middle of the extending direction (claim 3).

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 1 (A) (B) (C)
A first comparative example of the present invention will be described with reference to (D). In FIG. 1, a pneumatic tire T with a lug according to the present invention includes a pair of left and right sidewalls 1, a crown portion 2 which is continuous from both sidewalls 1 and extends between the sidewalls 1, and a center portion of the crown portion 2. And a tread 5 in which circumferentially arranged lugs 4 projecting in a V shape projecting from the portion toward the shoulder portion 3 inclining with respect to the circumferential direction are provided, and a central end of the crown portion of the lug 4 is provided. The rotation direction Q is set so that it comes into contact with the ground first and the shoulder end of the lug 4 comes into contact with the ground later, and a pair of left and right bead portions are fitted to the rim 6.

The stepping side walls 7 and 8 of the lug 4 arranged in a V-shape are first side walls 7 which are steeply raised on the side to be grounded first, and the first side wall 7 on the side to be grounded later. It is the second side wall 8 that rises more loosely, and the lug 4
The side wall 9 of the kick surface is formed so as to be steeper than the first and second side walls 7, 8. Specifically, the first side wall 7
Angle θ1 and the angle θ2 of the second side wall 8 are in the range of 20 ° to 60 ° under the condition of θ1 <θ2, preferably θ1 is 30 ° to 45 °, and θ2 is 30 ° to 50 °.
The angle θ3 of the side wall 9 of the kick surface is 20 ° or less.

2 and 3 show a second comparative example of the present invention. As shown in the figure, between one or both of the first and second side walls 7 and 8 and the lug top surface 4A,
The step portion 7A, which rises more sharply than the first and second side walls 7 and 8,
8A is formed, and in FIGS. 2 and 3, the step portions 7A and 8A are provided on both the first and second side walls 7 and 8. It should be noted that one of the stepped portions 7A and 8A (the second step in FIG. 4) is representatively shown in FIG. 4, which is a third comparative example.
It may be formed on the side wall 8).

Specifically, the height H1 of the step portions 7A and 8A
Is 0.02 to 0.15 of the lug height H, and the angle θ4 of the step portions 7A and 8A is 0 to 40 °. Here, if it is 0.02H or less, the bite to the ground becomes worse, and if it is 0.15 or more, the ground is excessively disturbed. Further, as shown in FIG. 1 (B) and FIGS. 2 and 4, in the lugs 4 arranged in a V shape, the first side wall 7 side is at a steep angle with respect to the tire equator line 0-0. The side wall 8 side has a gentle angle with respect to the tire equator line 0-0, and is folded in two in the middle in the extending direction. Reference numeral 4B is the bent portion.

FIGS. 5A and 5B show an embodiment of the present invention. As shown in the figure, in the tire T of this embodiment, the lugs 4 arranged in a V shape are
Either or both of the side walls 7 and 8 have been formed on the root side is steep and rises to the distal end side is loosely rises in two or more stages of the bending section in the lug section, FIG. 5 (A) folding portion 4B is Since it is one, the root part a on the root side is sudden
The tip b on the tip side rises sharply and rises from the bent portion 4B.
It is formed in a two-step bent cross section that rises gently, and has a root side a and a tip.
The side b has a two-step bent shape, while FIG.
Since there are two bent portions 4B, the root portion a on the root side is steep
Rises and the tip b on the tip side loosens from the bent portion 4B.
It is formed in a two-stage bent cross section that rises, and it rises gently
The pointed tip b is further paired with the first tip ba on the root side.
Then, the second tip portion bb on the tip side loosely rises from the bent portion 4B.
It has a bent cross section of two or more steps.

As shown in FIG. 6, the second side wall 8 of the lug 4 has a smaller (abrupt) inner inclination angle θ2 from the inner side toward the outer side and a larger outer side inclination angle θ2. With (slow), the elevation of the second side wall 8 itself can be a so-called twisted elevation. In addition, in FIGS.
Among the constituent actions described above, common parts are denoted by common reference numerals. [Example] Tire size 9.5-22 4PR air pressure 1.45 kgf / cm2 outer diameter 995 mm total width 230 mm tread width 230 mm rim width 7 inches lug height H 40 mm stepped portion H1 5 mm θ1 20 ° θ2 46 ° θ3 20 ° air An experiment was carried out in a wetland condition for a filled tire (the former) and a pneumatic tire which is the same as the tire and has no stepped portion (the latter). The result is shown in FIG. 7. The former becomes the curve of reference sign S1 and the latter becomes the curve of reference sign S2, and the slip ratio was better when the step portion was formed than when it was not formed.

However, by adopting the above-mentioned lug shape,
The intended purpose could be achieved without forming a step.

[0018]

As described in detail above, according to the present invention, it is possible to provide a pneumatic tire with a lug which can be commonly used for paddy fields and uplands and is excellent in traction performance and slip performance.

[Brief description of drawings]

FIG. 1 shows a first comparative example of the present invention, in which (A) is an inclined view,
(B) is a main part plan view, (C) is a sectional view taken along the line aa of (B),
(D) is a bb sectional view of (B).

FIG. 2 is a main part plan view showing a second comparative example of the present invention.

3 is a cross-sectional view of the lug of FIG.

FIG. 4 is a main part plan view showing a third comparative example of the present invention.

FIG. 5 is a lug sectional view showing an embodiment of the present invention.

FIG. 6 is a main part plan view showing a modified example of the lug side wall.

FIG. 7 is a graph of actual vehicle test results showing the relationship between the lug inclination angle and the self-propelled slip ratio.

[Explanation of symbols]

1 side wall 2 Crown part 3 shoulder 4 rugs 5 tread 7 First side wall 8 Second side wall 9 Kicking side wall

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Claims (3)

(57) [Claims] 1. A pair of left and right side walls (1), and a side wall (1) continuous from both side walls (1).
The crown portion (2) straddling between and the crown portion (2)
A tread (5) in which a lug (4) extending from the central portion toward the shoulder portion (3) with an inclination with respect to the circumferential direction is provided so as to project in a V shape and arranged in the circumferential direction. A pneumatic tire (T) with a lug, in which the center end of the crown portion of the lug (4) comes in contact first and the shoulder end of the lug (4) comes in contact with a delay, the lugs being arranged in a V shape. The stepped side walls (7) and (8) of (4) are the first side walls (7) that are steeply raised on the side to be grounded first, and are raised more gently on the side to be grounded later than the first side walls (7). The side wall (9) of the rug (4) is the first side wall.
2 The lugs (4), which are formed to rise steeply from the side walls (7) and (8) and are arranged in a V shape, are
Either one or both of the side walls (7) and (8) rise steeply at the root side root part (a) in the lug cross section.
The tip (b) on the tip side loosely rises from the bent portion (4B)
A pneumatic tire with a lug, which is formed to have a two-step bent cross section . 2. A pair of left and right sidewalls (1) and a sidewall (1) continuous from both sidewalls (1).
The crown portion (2) straddling between and the crown portion (2)
A tread (5) in which a lug (4) extending from the central portion toward the shoulder portion (3) with an inclination with respect to the circumferential direction is provided so as to project in a V shape and arranged in the circumferential direction. A pneumatic tire (T) with a lug, in which the center end of the crown portion of the lug (4) comes in contact first and the shoulder end of the lug (4) comes in contact with a delay, the lugs being arranged in a V shape. The stepped side walls (7) and (8) of (4) are the first side walls (7) that are steeply raised on the side to be grounded first, and are raised more gently on the side to be grounded later than the first side walls (7). The side wall (9) of the rug (4) is the first side wall.
2 The lugs (4), which are formed to rise steeply from the side walls (7) and (8) and are arranged in a V shape, are
Either one or both of the side walls (7) and (8) rise steeply at the root side root part (a) in the lug cross section.
The tip (b) on the tip side loosely rises from the bent portion (4B)
It is formed in a two-step bent cross section that rises gently
The tip (b) is further to the first tip (ba) on the root side.
The second tip (bb) on the tip side from the bent portion (4B)
Must be raised and have a cross section of two or more steps
Pneumatic tire with a lug and said. 3. The tire equator line (0-0) on the first side wall (7) side of the lugs (4) arranged in a V shape.
At a steep angle with respect to the second side wall (8) side, the tire equator line (0
The lugged pneumatic tire according to claim 1 or 2, wherein the pneumatic tire has a gentle angle with respect to −0) and is folded in two in the middle of the stretching direction.