RU2799179C9 - Agricultural vehicle tire tread - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: tread (2) contains the main elements (21) of the tread pattern with a radial height HR1 and the secondary elements (31) of the tread pattern, located longitudinally between the main elements (21) of the tread pattern, with a radial height HR2, having a front surface (312), which is inclined forward to the corner α with respect to the radial direction (Z) in accordance with the direction (15) of the tread movement, and the contact surface (311) tilted back at an angle β relative to the radial direction (Z) in accordance with the direction (15) of the tread movement. According to the invention, the ratio of HR1 to HR2 is at least 4, the angle α ranges from -5 to 15 degrees, the angle β is from 95 to 110 degrees, and the longitudinal pitch L, which separates the secondary tread elements from each other, is from 5 to 50 mm.

EFFECT: improved traction characteristics on loose soil.

10 cl, 7 dwg

Description

The present invention relates to a tire tread for equipping an agricultural vehicle, and in particular to a tire tread having improved traction on loose ground.

Without being limited to this type of application, the invention will be described in more detail in relation to a multi-purpose agricultural vehicle, that is, a vehicle that can travel both in fields on loose soil and on highways, such as an agricultural tractor.

The tread for an agricultural vehicle may, for example, be connected to a tire periphery, a solid tire, a non-pneumatic resilient wheel, or a track. Such a tread is designed to roll on various types of ground, such as more or less dense field soil, dirt roads leading to fields, and paved road surfaces. Taking into account the variety of applications - in the fields and on the road, an agricultural vehicle tire must have properties that provide an appropriate combination of traction in the field on loose soil, resistance to destruction, wear resistance on the road, rolling resistance and vibration comfort on the road. automobile road.

Definitions

In this document, the radial direction refers to any direction perpendicular to the axis of rotation of the wheel. By "wheel" is meant, but not limited to, a tire or a solid tire located on a rim, not a pneumatic resilient tire or a track. This direction corresponds to the direction of tread thickness and is usually referred to as Z.

By transverse or axial direction is meant a direction parallel to the axis of rotation of the wheel. This direction is usually referred to as Y.

A circular direction is a direction tangential to any circle centered on the axis of rotation of the wheel. Such a direction is perpendicular to both the axial direction and the radial direction. This direction is usually denoted as X.

Typically, a tire has a crown comprising, radially outward, a tread configured to contact the ground via the tread surface, two beads configured to contact the rim on which the tire is mounted, and two sidewalls connecting the crown to the beads. An agricultural tractor tire comprises a carcass reinforcement anchored into each sidewall, usually made of at least one layer of textile reinforcing elements.

Radially outside, the carcass reinforcement is usually surrounded by a crown reinforcement made of a plurality of working layers, with each working layer consisting of textile or metal reinforcements coated with an elastomeric material. Reinforcing elements usually move from one layer to the next.

The tread, which is the part of the tire intended to come into contact with the ground during travel, comprises a bearing surface parallel or substantially parallel to the crown reinforcement of the tire. The elements of the tread pattern are molded into the bearing surface of the tread.

Instead of a tire or solid tire intended to be mounted on a rigid rim, the tread may also be connected to an agricultural vehicle track, or to a non-pneumatic resilient wheel, ie structurally deformable and free of compressed air.

State of the art

Tire treads for agricultural vehicles traditionally comprise ridges that extend from the center of the tread to the shoulders. These projections are located on both sides of the mid equatorial plane of the tire so as to form a V-shaped pattern, with the tip of the V-shaped pattern (or also the chevron pattern) intended to enter the ground contact zone first. The protrusions are spaced apart so as to form grooves or grooves, the width of these grooves being set to allow good operation both on a highway and on loose ground. The lugs are symmetrical about the mid equatorial plane of the tire, typically with a circumferential offset between the two rows of lugs, similar to that obtained by rotating one half of the tread relative to the other half of the tread about the tire's axle. In addition, the protrusions may be continuous or discontinuous and may be distributed in a circular direction at constant or variable intervals. The protrusions have a contact surface designed to move on hard ground, such as, for example, roads used to reach fields, and a front surface, designed to transmit driving force when the agricultural vehicle travels on loose soil, characteristic for soil fields.

A persistent problem is associated with the poor traction characteristics of the known treads on loose soil, when the radial height of the protrusions is significantly reduced as a result of wear. The performance of agricultural vehicles is directly related to their tractive capacity on loose soil. Improving this characteristic over the lifetime of the tire would allow the user to not only improve the performance of their equipment, but also reduce operating costs. It would be desirable if the improvement in wear traction does not adversely affect other aspects of the vehicle's performance, such as, for example, comfort and the ability to travel on a road at a sufficiently high speed.

Disclosure of the essence of the invention

Said problem according to the invention is solved by means of a tread for the driving axle of an agricultural vehicle, comprising main tread elements and secondary tread elements extending radially outward from the bearing surface, wherein the main tread elements have a radial height HR1, and the secondary tread elements are located longitudinally between the main elements of the tread pattern and have a radial height of HR2, characterized in that

- the ratio of HR1 to HR2 is at least 4;

- secondary tread pattern elements that are substantially parallel to the tread pattern elements and have a triangular profile, have a contact surface and a rake surface, wherein said rake surface is inclined forward at an angle α relative to the radial direction in accordance with the direction of movement of the tread, and said contact surface is inclined back at an angle β relative to the radial direction in accordance with the direction of movement of the tread;

- angle α is from -5 to 15 degrees;

- angle β is from 95 to 110 degrees; And

- the longitudinal pitch L separating the minor elements of the tread pattern from each other is from 5 mm to 50 mm.

Preferably, the angle α is at least 2 degrees.

Preferably, the angle β is at least 100 degrees.

Preferably, the longitudinal pitch L separating the minor elements of the tread pattern from each other is between 15 mm and 25 mm.

Preferably, the radial height HR2 of the secondary tread pattern elements is between 2 and 8 mm.

Preferably, the front and contact surfaces of the secondary elements form ribs that are inclined relative to the axial direction (Y) of the tread.

Preferably, the ribs form a V-shaped pattern, with the point of the V pointing towards the front of the tread according to the direction of travel.

The invention also relates to a tire, track and non-pneumatic wheel containing this type of tread.

Other features and advantages of the invention will become apparent from the following description, given with reference to the accompanying drawings, which show a non-limiting example of an embodiment of the invention.

Brief description of the drawings

Figure 1 is a perspective view of a tire containing a tread according to a first embodiment of the invention.

Fig. 2 shows, on an enlarged scale, section D1 of Fig. 1.

Figure 3 shows a section of the tire from figure 1 along the median equatorial plane.

Fig. 4 is a front view illustrating a tire including a tread according to the second embodiment of the invention.

Figure 5 is a perspective view of a caterpillar track containing the tread of Figure 5.

FIG. 6 shows the tread section D2 of FIG. 5 on an enlarged scale.

Fig. 7 is an enlarged side view of a part of the caterpillar track of Fig. 5.

Implementation of the invention

Figure 1 shows a tire 1 containing a tread 2 according to the invention. This tire is designed to equip the drive axle of an agricultural vehicle. The tire also has sidewalls 11 and rims 12 in a known manner. The preferred direction of movement of the tire is indicated by arrows 15 which are formed on the sidewalls of the tire and/or on the shoulder of the tread. The tread 2 comprises primary tread pattern elements 21 in the form of a set of ribs extending radially outward and distributed along the tread periphery, and secondary tread pattern elements 31 which have a much lower radial height and are located in the circumferential direction between the lugs.

In the area D1, which is shown in an enlarged size in figure 2, you can better see the overall shape and orientation of the secondary elements 31 of the tread pattern. In this embodiment, five minor tread pattern elements are located between the two lugs 21. Each of these secondary tread features is substantially parallel to the lugs, has a triangular profile, and, in the preferred direction of rotation, comprises a rake surface 312 and a contact surface 311, with the rake surface having an orientation close to the Z radial direction, and the contact surface having an orientation close to the longitudinal direction X. The front and contact surfaces form ribs 313.

FIG. 3 is a mid equatorial plane cross section of a tire (PEM mid equatorial plane shown in FIG. 4) illustrating the relationships of various tread pattern elements in accordance with this embodiment of the invention. The main elements of the tread pattern, i.e. in this case, the lugs 21 have a radial height HR1 of approximately 40 mm, while the secondary treads 31 have a radial height HR2 of approximately 4.3 mm. According to the invention, the ratio of HR1 to HR2 is at least 4 and in the embodiment described here is 9.3.

Figure 3 also shows the orientation of the front 312 and contact 311 surfaces of the minor elements of the tread pattern. The front surfaces slant forward at an angle α relative to the radial direction in the preferred direction of tread movement (indicated by arrows 15), and the contact surfaces 311 slope backwards at an angle β relative to the radial direction Z in the preferred direction of tread movement. According to an embodiment of the invention, α is about 3 degrees and β is about 100 degrees.

The secondary elements of the tread pattern are distributed with a longitudinal pitch L, which, according to the invention, is between 5 mm and 50 mm. In the present embodiment, the pitch L is approximately 25 mm.

Figure 4 shows a front view of a tire containing a tread according to the invention, made in accordance with another embodiment. This view clearly shows the median equatorial plane PEM, perpendicular to the axial direction Y and dividing the tread into two equal halves.

In the embodiment of FIG. 4, the main elements of the tread pattern are blocks 22 rather than lugs 21 as in the embodiment of FIGS. 1-3. On both sides of the center blocks 221, two intermediate blocks 222 and a shoulder block 223 form rows oriented similarly to the protrusions of the first embodiment. The secondary elements 31 of the tread pattern are similar to those shown in the previous figures.

This figure also makes it possible to show more clearly that the front and contact surfaces of the secondary tread pattern elements form ribs 313 that are inclined relative to the axial direction of the tread. The ribs 313 form a V-shaped pattern with the tip of the V facing the front side of the tread in the direction of travel.

The treads shown here are perfectly symmetrical about the median equatorial plane of the tyre. In embodiments not shown, the two tread halves located on both sides of the median equatorial plane may, on the other hand, be offset relative to each other in a circular direction, as is often the case with lug tread patterns of prior art agricultural tires.

Figure 5 shows a third embodiment of the tread according to the invention, referring in this case to the caterpillar track 4. This tread comprises primary tread elements in the form of blocks 41 and secondary tread elements 42 located between the projections in the circumferential direction in a manner similar to that described in in relation to the previous figures. The orientations, dimensions and pitch in the longitudinal direction of these minor elements of the tread pattern are subject to the same rules as described above in relation to the tire.

Comparative tests have shown that the treads shown in figures 1 and 4 provide a very significant increase in traction on loose ground when the main elements of the tread pattern are completely worn compared to a traditional tread. Depending on the test conditions and in particular on the slip factor, an increase of 10% and 25% was registered.

The invention is not limited only to these described exemplary embodiments, and various changes can be made to it without going beyond the scope of protection defined by the claims.

Claims (16)

1. Protector (2) for the driving axle of an agricultural vehicle, containing the main elements (21) of the tread pattern and the secondary elements (31) of the tread pattern, passing radially outward from the bearing surface (23), and the main elements of the tread pattern have a radial height HR1, and the secondary tread elements are located longitudinally between the main tread elements and have a radial height of HR2, characterized in that: the ratio of HR1 to HR2 is at least 4; secondary tread features that are substantially parallel to the tread features and have a triangular profile, have a contact surface (311) and a front surface (312), wherein said front surface is inclined forward at an angle α with respect to the radial direction (Z) in accordance with the direction (15) movement of the tread, and the specified contact surface is inclined back at an angle β relative to the radial direction (Z) in accordance with the direction (15) movement of the tread; angle α is from - 5 to 15 degrees; the angle β is from 95 to 110 degrees; And the longitudinal pitch L separating the minor elements of the tread pattern from each other is from 5 to 50 mm. 2. The tread according to claim 1, wherein the angle α is at least 2 degrees. 3. The tread according to claim 1 or 2, wherein the angle β is at least 100 degrees. 4. A tread according to any one of the preceding claims, wherein the longitudinal pitch L separating the minor elements of the tread pattern from each other is between 15 and 25 mm. 5. A tread according to any one of the preceding claims, wherein the secondary tread pattern radial height HR2 is between 2 and 8 mm. 6. A tread according to any of the preceding claims, wherein the front and contact surfaces of the secondary elements form ribs (313) that are inclined relative to the axial direction (Y) of the tread. 7. The tread according to claim 6, wherein the ribs (313) form a V-shaped pattern, with the tip of the V pointing towards the front of the tread in accordance with the direction (15) of movement. 8. Tire (1) comprising a tread according to any one of the preceding claims. 9. Non-pneumatic wheel containing a tread according to any one of claims 1 to 7. 10. A track for an agricultural vehicle, comprising a tread according to any one of claims 1 to 7.