JPH06278413A - Heavy load tire for snowy and icy road - Google Patents

Abstract

PURPOSE:To offer a heavy load tire for snowy and icy road compatible with improvement of turning on a snowy and icy road and improvement of stability of driving straight and stability of operation on a dry road. CONSTITUTION:A plural number of blocks 14 are divided into a central block line 18 by a pair of main grooves 16 in the circumferential direction with a tire equatorial surface CL in between and an outer side block line 20 arranged on the outer side in the tire width direction of the central block line 18 while a wide slant groove 30 and a narrow slant groove 32 sectioning the block 14 on the outer side block line 20 in the circumferential direction of the tire are inclined in a arrow feather shape. When driving straight, stability of driving straight and operation on a dry road travelling are assured and when a slippage angle and large camber angle are given, the outer side block line 20 contacts the ground and the edge element on the wide slant groove 30 and the narrow slant groove 32 sides of the outer side block line 20 can be brought close to each other in parallel against the vehicle advancing direction thereby improves the turning of a vehicle on a snowy and icy road by virtue of edge effect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heavy-duty tire for ice and snow roads used in a snow remover, and more particularly to a heavy-duty tire for ice and snow roads that can achieve both steering performance and high-speed running performance.

[0002]

2. Description of the Related Art Motor graders are used to remove snow from snowy roads. In Motor Grader,
In order to improve turning performance (reducing steering force, turning radius, etc.), the steering wheel (front wheel) is tilted to the left and right, and a very large camber angle is added to the steering wheel when turning. To be done.

The main function of the pattern applied to the heavy-duty tire for ice and snow roads for the steered wheels of such a motor grader is to secure the braking force on the frozen road surface and also to ensure the turning ability under the above conditions ( It is important to prevent skidding when turning.

From this point of view, the pattern for this application is
A pattern having a block row is mainly used, and in order to improve skid resistance during turning, a directional pattern in which the block 100 is obliquely arranged with respect to the tire equatorial plane CL is often used as shown in FIG. ing.

[0005]

By the way, the inclination θ of the arrangement direction of the blocks 100 is shallow with respect to the tire equatorial plane CL in an attempt to improve the turning performance in the heavy load tire for ice and snow roads having a directional pattern. When the angle is set, an edge component along the tire circumferential direction is reduced, and there is a trade-off relationship that straight-line / steering stability is deteriorated when driving on a dry road. In particular, in recent years, motor graders have been improving their moving speeds on site, and the conventional technology improves the turning performance on ice and snow roads and improves the straight-line and steering stability on dry roads. , Could not be achieved at the same time.

As shown in FIG. 10, a plurality of main grooves 112 and narrow grooves 114 extending in the circumferential direction and a plurality of sub-grooves 116 inclined at a small angle with respect to the tire axial direction are provided. There is a heavy load tire 120 having a block pattern in which the parallelogram blocks 118 are arranged so as to be adjacent to each other in the width direction so as to be opposite to each other. However, such a heavy load tire 120 is used for running on a dry road. Although straight running stability can be ensured, there is a problem that the edge component when adding a large camber angle when turning on an ice / snow road is not sufficient, and the turning performance on the ice / snow road is poor.

In consideration of the above facts, the present invention provides a heavy-duty tire for ice and snow roads, which is capable of improving both the turning performance on ice and snow roads and the improvement of straight running stability and steering stability on dry roads. The purpose is to do.

[0008]

As a result of various investigations by the inventors, in the motor grader which is the main snow removing machine,
When turning on an actual ice / snow road, the camber angle is 1 when measured.
It was found that the slip angle reached 8 ° to 25 ° and the slip angle reached 30 ° to 35 °.

When the inventors examined the ground contact shape under these conditions, the ground contact is at the T on the camber angle addition side.
It was only / 3 (1/3 of the tread width), and it was revealed that only blocks in this range contributed during turning.

Furthermore, the amount of skidding during turning on an ice and snow road,
When the relationship with the edge component of the pattern block was confirmed by experiments, it was found that the larger the edge component in the straight running direction of the tire, the higher the skid prevention effect. this is,
This is because the edge effect and snow column shearing effect are maximized in this direction.

The heavy-duty tire for ice and snow roads of the present invention has been made in view of the above facts. The tread has at least two main grooves extending in the circumferential direction, and the main groove and the sub-grooves intersecting the main groove are provided. In a heavy load tire for ice and snow roads having a pattern divided into a large number of blocks, the large number of blocks are sandwiched by the main grooves, and a central block row extending along the tire circumferential direction near the tire equatorial plane, and the central portion. The sub-groove is divided into an outer block row that is arranged on the tire width direction outer side of the block row and extends along the tire circumferential direction, and a sub-groove that partitions the blocks of the outer block row in the tire circumferential direction has an arrow blade shape. The feature is that it is inclined.

[0012]

In the heavy-duty ice / snow road tire of the present invention, when the tire is not straightened, the central block row having an edge component along the tire circumferential direction disposed near the equatorial plane of the tire having a high ground contact pressure is used. In addition, straight running stability and steering stability are ensured when driving on a dry road.

On the other hand, when the slip angle and the camber angle are imparted by the turning of the vehicle, the outer block row on the camber angle imparting side is grounded. In this outer block row, since the sub-grooves that divide the block in the tire circumferential direction are inclined in an arrow blade shape, the edge components on both sides in the tire circumferential direction of the outer block row are parallel to the traveling direction of the vehicle. It is possible to approach, that is, to approach at a right angle to the direction of the cornering force. Therefore, at the time of turning with a camber angle, the action of the edge components on both sides in the tire circumferential direction of the blocks forming the outer block row enhances the skid-prevention effect and improves the turning ability on the ice and snow road. .

In the outer block row, it is preferable that the blocks are arranged with their edges aligned. Further, in order to eliminate the difference in performance depending on the turning direction, it is preferable to arrange the both outer block rows in a direction symmetrical with respect to the tire equatorial plane.

[0015]

【Example】

[First Embodiment] A heavy load tire 10 for an ice and snow road according to a first embodiment of the present invention will be described with reference to Figs.

Since the internal structure of the heavy load tire 10 for ice and snow roads is the same as the structure of a normal radial tire, a description of the internal structure will be omitted.

As shown in FIG. 1, a heavy-duty tire 10 for ice and snow roads according to this embodiment (tire size: 14.00R24).
Has a so-called block pattern, and the tread 12
A plurality of blocks 14 are disposed in the tire, and the plurality of blocks 14 are roughly divided into the tire equatorial plane CL.
A central block row 18 arranged on both sides of the tire equatorial plane CL by a pair of circumferential main grooves 16 provided on both sides of the tire.
And the tire width direction of the central block row 18 (direction of arrow A)
It is divided into outer block rows 20 arranged on the outer side.

Here, when the width of the central block row 18 is w and the width of the tread tread portion is T, w / T is 0.2 to.
It is desirable to set to 0.6, preferably 0.3 to 0.5.

Blocks 1 constituting the central block row 18
Reference numeral 4 denotes the circumferential main groove 16 described above, a pair of narrow grooves 22 provided on both sides of the tire equatorial plane CL and extending in the circumferential direction, and the tire equatorial plane CL side is closer to the tire rotation direction kicking side than the shoulder 24 side (arrow). A plurality of inclined grooves 26 that are inclined at a small angle with respect to the tire equatorial plane CL so as to be on the B direction side),
Is partitioned by.

That is, each block 1 in the central block row 18
4, the tire equatorial plane CL is on both sides in the tire width direction.
The direction is along, in other words, each block 1
In No. 4, the edge component in the direction along the tire equatorial plane CL is provided.

Further, each block 1 in the central block row 18
4 are respectively provided with sipes 28. The direction of the sipes 28 of the block 14 on the tire equatorial plane CL is substantially along the tire width direction, and the blocks 14 on both sides are provided.
The direction of the sipe 28 is substantially along the inclined groove 26.

On the other hand, the blocks 14 of the outer block row 20
Is the circumferential main groove 16 described above, and a plurality of wide inclined grooves 30 as sub-grooves that are inclined so that the tire equatorial plane CL side is on the kicking side in the tire rotation direction (arrow B direction side) with respect to the shoulder 24 side. , A narrow slant groove 32, which is also provided as a sub-groove, disposed between the wide slant grooves 30 and provided along the wide slant groove 30, and a reverse slant groove 34 intersecting the wide slant groove 30. ing.

That is, each block 1 in the outer block row 20
4, both sides in the tire circumferential direction are along the wide inclined groove 30, that is, each block 14
In, the edge component in the direction along the wide inclined groove 30 is provided. The wide inclined groove 30 on one side and the wide inclined groove 30 on the other side across the tire equatorial plane CL are in the tire circumferential direction (the arrow B direction and the direction opposite to the arrow B direction).
It is arranged to be shifted by a half pitch.

The blocks 14 of the outer block row 20 are provided with sipes 36 extending substantially along the wide inclined groove 30.

Here, the direction of both sides in the tire circumferential direction of each block 14 of the outer block row 20 (the wide inclined groove 3
The same as the direction of 0) is 20 ° with respect to the tire equatorial plane CL.
It is desirable to incline in the range of 70 °, preferably 30 ° to 60 °. In the present embodiment, the inclination angles θ of both side portions in the tire circumferential direction of each block 14 of the outer block row 20 with respect to the tire equatorial plane CL are 55 ° on average.
Is. In terms of turning around on ice and snow roads, θ is 30
The angle is preferably from 35 ° to 35 °, but is set to 55 ° because there is concern that the rigidity of each block 14 may decrease.

As shown in FIG. 2, in the heavy-duty tire 10 for ice and snow roads of this embodiment, the end portion of the tread 12 has a square shape (so-called square shoulder), and the tread 12 is treaded at the time of normal internal pressure filling. The width T of the surface portion is 340 mm and the width w of the central block row 18 is 140 mm.
Is 0.41. Further, the tread surface of the tread 12 is formed by a single circular arc, and its radius of curvature CR is 7
It is 00 mm.

Next, the operation of this embodiment will be described. Footprint 40 when traveling straight when the heavy load tire 10 for ice and snow roads of this embodiment is used as a steering wheel of a motor grader.
Is as shown in FIG. 3 when a normal load is applied (3450 kg is applied), and near the tire equatorial plane CL with high ground contact pressure,
Since there are many edge components along the tire circumferential direction, straight running stability and steering stability when driving on a dry road are improved.

On the other hand, when the motor grader turns, for example, when the slip angle θ _{S of the} front wheels becomes 30 ° to 35 ° and the camber angle becomes approximately 25 °, the footprint 42 becomes as shown in FIG. In the width T of the tread portion, only a region of approximately 1/3 of the camber angle imparting side (the arrow C direction side) comes into contact with the ground. In this case, the central block row 18 grounds only about 18 mm in width of the block 14 on one side, and most of them are on the outer block row 2 on the camber angle imparting side (arrow C side).
0 comes into contact with the ground, and both side portions in the tire circumferential direction of each block 14 of the outer block row 20 are substantially parallel to the traveling direction of the motor grader (direction of arrow D) and the direction of the cornering force (direction of arrow E). It becomes almost right angle. That is, when the motor grader turns, the side slip prevention effect is enhanced by the action of the edge components on both sides in the tire circumferential direction of each block 14 in the outer block row 20.

In order to increase the edge component in the direction along the tire circumferential direction, it is effective to dispose the edge component near the tire equatorial plane CL where the ground contact pressure is large. If the relationship w / T between the width T and the width w of the central block row 18 is less than 0.3, the rigidity of the central block row 18 in the tire rotation axis direction (tire width direction) decreases, so that the central block row 18 has Block 14
In particular, chipping and uneven wear are likely to occur, which is not preferable, and particularly when w / T is less than 0.2, it rapidly deteriorates.

When w / T exceeds 0.5,
As a result, the width of the outer block row 20 becomes 0.25 T or less, and therefore, under the addition of a large camber angle when turning on an ice and snow road, an edge component that is substantially parallel to the traveling direction (direction of arrow D). The ratio of the block 14 of the outer block row 20 having the occupancy in the ground is reduced to 80% or less, and the turning performance on the ice and snow road is deteriorated, and the turning is performed especially when w / T exceeds 0.6. The performance is significantly reduced.

[Second Embodiment] A heavy load tire 10 for an ice and snow road according to a second embodiment of the present invention will be described with reference to FIGS. 5 to 8. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIGS. 5 and 6, the heavy-duty ice / snow road tire 10 of this embodiment also has a block pattern, like the heavy-duty ice / snow road tire 10 of the first embodiment.

In the heavy load tire 10 for ice and snow roads of the present embodiment, a pair of first main grooves 50 extending in the circumferential direction are provided on both sides of the tire equatorial plane CL, and the tires of the first main grooves 50 are provided. A second main groove 5 extending in the circumferential direction is provided on both outer sides in the axial direction.
2 are provided respectively. Between the pair of first main grooves 50, a pair of narrow grooves 54 extending in the circumferential direction are provided on both sides of the tire equatorial plane CL, and further, the first main groove 50 and the second main grooves 50 are provided. A narrow groove 56 that also extends in the circumferential direction is provided between the main groove 52 and the main groove 52. Further, on the outer side of the second main groove 52 in the tire axial direction, a narrow groove 58 extending in the circumferential direction is provided.
Is provided.

The plurality of blocks 14 are roughly divided into a central block row 60 sandwiched by the first main grooves 50,
It is divided into an outer block row 62 sandwiched between the first main groove 50 and the second main groove 52, and a shoulder side block row 64 provided outside the second main groove 52 in the tire width direction.

Further, the tread 12 is provided with an inclined groove 66 as a sub groove extending from the vicinity of the tire equatorial plane CL toward the shoulder side. The inclined groove 66 is inclined so that the tire equatorial plane CL side is closer to the kicking side in the tire rotation direction (arrow B direction side) than the shoulder 24 side.

Block 1 constituting the central block row 60
4 is partitioned by the above-mentioned first main groove 50, narrow groove 54, and inclined groove 66. Each block 14 of the central block row 60 is provided with a sipe 68, and the direction of the sipe 68 of the block 14 on the tire equatorial plane CL is substantially along the tire width direction. The direction of the sipe 68 of the block 14 is substantially along the inclined groove 54.

On the other hand, the blocks 14 in the outer block row 62
Is partitioned by the above-mentioned first main groove 50, second main groove 52, narrow groove 56, and inclined groove 66. It should be noted that each block 14 of the outer block row 62 is provided with a sipe 70 substantially along the inclined groove 66.

Further, the shoulder side block row 64 is
It is partitioned by the second main groove 52, the narrow groove 58, and the inclined groove 66. The shoulder side block row 64
Each block 14 is provided with sipes 72 extending substantially along the inclined groove 66.

The inclined groove 66 on one side and the inclined groove 66 on the other side across the tire equatorial plane CL are arranged so as to be shifted by a half pitch in the tire circumferential direction.

In the present embodiment, the outer block row 62
In each block 14, the inclination angle θ with respect to the tire equatorial plane CL on both sides in the tire circumferential direction is 55 ° on average.
In terms of turning around on ice and snow roads, θ is 30 ° to 3
Although 5 ° is preferable, it is set to 55 ° because there is concern that the rigidity of each block 14 may be reduced.

As shown in FIG. 6, in the heavy load tire 10 for ice and snow roads of the present embodiment, the end portion of the tread 12 has a round shape, and the width T of the tread portion of the tread 12 at the time of normal internal pressure filling. Is 313 mm and the width w of the central block row 60 is 12
It is 3 mm and w / T is 0.39. Further, the tread 12 has a radius of curvature CR of 700 mm at the center and a radius of curvature SR of 12 at the end of the tread 12.
It is set to 0 mm.

Next, the operation of this embodiment will be described. Footprint 74 when traveling straight when the heavy-duty ice / snow road tire 10 of the present embodiment is used as a steering wheel of a motor grader
Is as shown in FIG. 7 (when a normal load of 3450 kg is added). Like the heavy-duty tire 10 for ice and snow roads of the first embodiment, the heavy-duty ice and snow road tire 10 of the present embodiment also has many edge components along the tire circumferential direction in the vicinity of the tire equatorial plane CL with a high ground contact pressure. Therefore, straight running stability and steering stability when driving on a dry road are improved.

Further, when the motor grader turns, the slip angle θ _{S of the} front wheels is 30 ° to 35 ° and the camber angle is about 25.
The footprint 80 when the angle becomes 0 is as shown in FIG. At this time, the heavy-duty tire 1 for ice and snow roads of the present embodiment
0 is also similar to the heavy-duty tire 10 for ice and snow roads of the first embodiment,
In the width T of the tread surface, the outer block row 62 on the camber angle imparting side (arrow C direction side) is grounded. Also in the case of this embodiment, each block 1 of the outer block row 62
Both side portions of the tire circumferential direction of 4 are substantially parallel to the traveling direction of the motor grader (direction of arrow D) and substantially perpendicular to the direction of the cornering force. Therefore, when the motor grader turns, the outer block row 62 The side slip prevention effect is enhanced by the action of the edge components on both sides in the tire circumferential direction of each block 14.

[Test Example] In order to confirm the effect of the present invention, the heavy load tire for ice and snow roads to which the present invention is applied (the heavy load tire for ice and snow roads of the second embodiment) and the conventional heavy load tire for ice and snow roads (Tire shown in FIG. 9, tire size: 14.0
0R24) was attached to each motor grader, and the turning performance on ice and snow roads and the steering stability when driving straight on dry roads were examined.

The turning performance on the ice and snow road was evaluated by the ice and snow road turning time and the lateral G when the ice and snow road was turning. The ice-snow road turning time is 3 at the maximum speed that can keep the turning radius.
The time taken to make a lap was measured, and the lateral G when turning on an ice and snowy road was measured the lateral G at that time.

Further, the straight running stability and steering stability when driving on a dry road were evaluated by the feeling of the test driver. Note that this evaluation is a five-level evaluation, and the larger the numerical value, the better the straight running stability and the steering stability.

[0047]

[Table 1]

Also from the test results shown in Table 1 above, the heavy load tire for ice and snow roads to which the present invention is applied is compared with the conventional heavy load tire for ice and snow roads, and the turning performance on the ice and snow road and the dry road are improved. It is clear that both the straight running stability and the steering stability in driving are excellent.

[0049]

As described above, since the heavy-duty tire for ice and snow roads of the present invention has the above-described structure, it improves the turning performance on ice and snow roads, and the straight running stability and steering stability on dry roads. It has an excellent effect that both improvement of

[Brief description of drawings]

FIG. 1 is a development view of a tread of a heavy duty tire for ice and snow roads according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a heavy-duty tire for ice and snow roads according to the first embodiment of the present invention.

FIG. 3 is a footprint of the heavy-duty tire for ice and snow road according to the first embodiment of the present invention when the tire is straight ahead.

FIG. 4 is a footprint of the heavy-duty tire for ice and snow road according to the first embodiment of the present invention during turning.

FIG. 5 is a development view of a tread of a heavy duty tire for ice and snow roads according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional view of a heavy duty tire for ice and snow roads according to a second embodiment of the present invention.

FIG. 7 is a footprint of a heavy load tire for ice and snow road according to a second embodiment of the present invention when the tire is straight ahead.

FIG. 8 is a footprint at the time of turning of the heavy load tire for ice and snow road according to the second embodiment of the present invention.

FIG. 9 is a development view of a tread of a heavy load tire for ice and snow roads having a directional pattern according to a conventional example.

FIG. 10 is a development view of a tread of a heavy load tire for ice and snow roads according to another conventional example.

[Explanation of symbols]

 10 Heavy-duty tires for ice and snow roads 12 Tread 14 Block 16 Circumferential main groove 18 Central block row 20 Outer block row 30 Wide inclined groove (sub groove) 32 Narrow inclined groove (auxiliary groove) 50 First main groove 60 Central block Row 62 Outer block Row 66 Inclined groove (sub groove)

Claims (1)

[Claims] 1. A heavy load tire for ice and snow roads, comprising a tread having at least two main grooves extending in the circumferential direction, and having a pattern divided into a number of blocks by the main groove and sub-grooves intersecting with the main groove. The plurality of blocks are sandwiched by the main grooves and extend along the tire circumferential direction in the vicinity of the tire equatorial plane, and a central block row is disposed outside the central block row in the tire width direction along the tire circumferential direction. A heavy-duty tire for ice and snow roads, characterized in that the auxiliary groove is divided into an extending outer block row, and the sub-grooves that partition the blocks of the outer block row in the tire circumferential direction are inclined like arrow blades.