TYRE FOR AGRICULTURAL MACHINE

Abstract

It is provided a pneumatic tyre having an equatorial plane for an agricultural machine, comprising: a tread having a first and a second lateral tread edge, the axial distance between the first and second lateral tread edges being the width of the tread, wherein the tread comprises a plurality of lugs extending radially between an inner surface of the tread and a tread surface to come into contact with the ground; and first lugs extending from the first lateral tread edge toward the inner equatorial plane, having a shoulder portion extending from the first lateral tread edge and a nose portion at the inner equatorial plane, and each of the first lugs having: an arcuate leading edge that arcs from the first lateral tread edge to an axial leading nose edge next to a substantially circumferential inner nose edge, and an arcuate trailing edge that arcs from the first lateral tread edge to the substantially circumferential inner nose edge; and second lugs extending from the second lateral tread edge toward the inner equatorial plane, having a shoulder portion extending from the second lateral tread edge and a nose portion at the inner equatorial plane, and each of the second lugs having: an arcuate leading edge that arcs from the second lateral tread edge to an axial leading nose edge next to a substantially circumferential inner nose edge, and an arcuate trailing edge that arcs from the second lateral tread edge to the substantially circumferential inner nose edge, wherein for each lug the length of the substantially circumferential inner nose edge is longer than the length of the axial inner nose edge and the width of said lug increases from the corresponding shoulder portion to the nose portion of said lug.

Claims

1. A pneumatic tyre having an equatorial plane for an agricultural machine, comprising: a tread having a first and a second lateral tread edge, the axial distance between the first and second lateral tread edges being the width of the tread, wherein the tread comprises a plurality of lugs extending radially between an inner surface of the tread and a tread surface to come into contact with the ground; and first lugs extending from the first lateral tread edge toward the inner equatorial plane, having a shoulder portion extending from the first lateral tread edge and a nose portion at the inner equatorial plane, and each of the first lugs having: an arcuate leading edge that arcs from the first lateral tread edge to an axial leading nose edge next to a substantially circumferential inner nose edge, and an arcuate trailing edge that arcs from the first lateral tread edge to the substantially circumferential inner nose edge; and second lugs extending from the second lateral tread edge toward the inner equatorial plane, having a shoulder portion extending from the second lateral tread edge and a nose portion at the inner equatorial plane, and each of the second lugs having: an arcuate leading edge that arcs from the second lateral tread edge to an axial leading nose edge next to a substantially circumferential inner nose edge, and an arcuate trailing edge that arcs from the second lateral tread edge to the substantially circumferential inner nose edge, wherein for each lug the length of the substantially circumferential inner nose edge is longer than the length of the axial inner nose edge and the width of said lug increases from the corresponding shoulder portion to the nose portion of said lug.

2. The tyre according to claim 1, wherein the tread has n lugs which 38≤n≤46.

3. The tyre according to claim 1, wherein the size ratio of the tread surface a to the total surface of tread surface a and inner surface b is in a range a/(a+b) of ≥20% to ≤32%.

4. The tyre according to claim 1, wherein an angle α of a straight line, which passes through an inner nose tip that is the crossing point of the axial leading nose edge and the equatorial plane and an laterally outer end point of the arcuate leading edge, relative to the equatorial plane, is in a range from 46°≤α≤50°.

5. The tyre according to claim 1, wherein an angle β of a tangent (t.sub.e) to the arcuate leading edge at the lateral tread edge, relative to an axial line, is up to 20°.

6. The tyre according to claim 1, wherein the lug width at the lateral edge of the lug is in a range from ≥41 mm to ≤50 mm.

7. The tyre according to claim 1, wherein the lug width of the lug is in a range of ≥7.5% to ≤8.5% of the tread width.

8. The tyre according to claim 1, wherein the length of the substantially circumferential inner nose edge is in a range from ≥1.1 to ≤1.4 times, the length of the axial inner nose edge.

9. The tyre according to claim 1, wherein the length of the substantially circumferential inner nose edge is in a range from ≥36 mm to ≤45 mm.

10. The tyre according to claim 1, wherein the gap between the trailing edge of a first lug and the nose tip of a following lug which follows the first lug in circumferential direction, is in a range from ≥25 mm to ≤45 mm.

11. The tyre according to claim 1, wherein the radius of the arcuate leading edge is in a range of ≥75% to ≤80% of the tread width and/or the radius of the arcuate trailing edge is in a range of ≥75% to ≤90% of the tread width.

12. The tyre according to claim 1, wherein the size ratio of the tread surface a to the total surface of tread surface a and inner surface b is in a range a/(a+b) of ≥24% to ≤27%.

13. The tyre according to claim 1, wherein an angle α of a straight line, which passes through an inner nose tip that is the crossing point of the axial leading nose edge and the equatorial plane and an laterally outer end point of the arcuate leading edge, relative to the equatorial plane, is 49.5°.

14. The tyre according to claim 1, wherein the length of the substantially circumferential inner nose edge is in a range from ≥1.2 to ≤1.3 times, the length of the axial inner nose edge.

15. The tyre according to claim 1, wherein the gap between the trailing edge of a first lug and the nose tip of a following lug which follows the first lug in circumferential direction, is in a range from ≥32 mm to ≤40 mm.

Description

[0031] In the following the invention is explained in detail by example with reference to the enclosed drawings showing preferred embodiments of the present invention, wherein each feature can constitute solely or in combination an aspect of the invention. In the drawings:

[0032] FIG. 1: is a schematic view of a tyre tread for an agricultural machine,

[0033] FIG. 2: is a schematic view of a lug of a tread for an agricultural tyre of 650/65 R 42 dimension,

[0034] FIG. 3: is a schematic view of a lug of a tread for an agricultural tyre of 540/65 R 30 dimension,

[0035] FIG. 4: is a further schematic view of a lug of a tread for an agricultural tyre of 650/65 R 42 dimension.

[0036] The pneumatic tyre having an equatorial plane E for an agricultural machine as illustrated in FIG. 1 comprises a tread 2 having a first lateral tread edge 10 and a second lateral tread edge 20. The axial distance between the first and second lateral tread edges 10 and 20 is the width of the tread W. The tread 2 comprises a plurality of lugs 5 and 6 extending radially between an inner surface 4 of the tread 2 and a tread surface 3 that is to come into contact with the ground. The tread 2 comprises first lugs 5 extending from the first lateral tread edge 10 toward the inner equatorial plane E. The lugs 5 have a shoulder portion 30 extending from the first lateral tread edge 10 and a nose portion at the inner equatorial plane E. Each of the first lugs 5 has an arcuate leading edge 8 that arcs from the first lateral tread edge 10 to an axial leading nose edge 12 next to a substantially circumferential inner nose edge 16, and an arcuate trailing edge 14 that arcs from the first lateral tread edge 10 to the substantially circumferential inner nose edge 16. Second lugs 6 extend from the second lateral tread edge 20 toward the inner equatorial plane E. The second lugs 6 also have a shoulder portion 30 extending from the second lateral tread edge 20 and a nose portion at the inner equatorial plane E. Each of the second lugs 6 has an arcuate leading edge 8 that arcs from the second lateral tread edge 20 to an axial leading nose edge 12 next to a substantially circumferential inner nose edge 16, and an arcuate trailing edge 14 that arcs from the second lateral tread edge 20 to the substantially circumferential inner nose edge 16.

[0037] For each lug 5 and 6 the length of the substantially circumferential inner nose edge 16 is longer than the length of the axial inner nose edge 12 and the width L of said lug increases from the corresponding shoulder portion 30 to the nose portion 32 of said lug 5 and 6.

[0038] In the following different embodiments for the lug 5 of the tread 2 are described. Illustrated in FIG. 2 is the lug for an agricultural tyre of 650/65 R 42 dimension. Illustrated in FIG. 3 is the lug for an agricultural tyre of 540/65 R 30 dimension. Such treads may comprise 46 or 38 lugs, respectively.

[0039] The lug 5 shown in FIG. 2 has an arcuate leading edge 8 that arcs from the lateral tread edge 10 to the axial leading nose edge 12, and an arcuate trailing edge 14 that arcs from the lateral tread edge 10 to the substantially circumferential inner nose edge 16. The lug width L at the lateral tread edge 10 is 50 mm and increases to about 56 mm at the nose portion 32 of the lug. A straight line D passes through an inner nose tip I that is the crossing point of the axial leading nose edge 12 and the equatorial plane E and an laterally outer end point II of the arcuate leading edge 8 and provides an angle α of the line D relative to the equatorial plane E of 49.50°. A tangent t.sub.e to the arcuate leading edge 8 of the lug at the lateral tread edge 10, relative to an axial line A forms an angle β that is 20°. The length of the substantially circumferential inner nose edge 16 of 44.76 mm is about 1.2 times the length of the axial inner nose edge 12 of 36.71 mm.

[0040] The lug 5 shown in FIG. 3 also has an arcuate leading edge 8 and an arcuate trailing edge 14. The lug width L at the lateral tread edge 10 is 41 mm and increases to about 46 mm at the nose portion 32 of the lug. A straight line D passes through an inner nose tip I that is the crossing point of the axial leading nose edge 12 and the equatorial plane E and an laterally outer end point II of the arcuate leading edge 8 and provides an angle α of the line D relative to the equatorial plane E of 49.50°. A tangent t.sub.e to the arcuate leading edge 8 of the lug at the lateral tread edge 10, relative to an axial line A forms an angle β that is 20°. The length of the substantially circumferential inner nose edge 16 of 36.56 mm is about 1.2 times the length of the axial inner nose edge 12 of 30.18 mm.

[0041] FIG. 4 is a further schematic view of a lug of a tread for an agricultural tyre of 650/65 R 42 dimension. FIG. 4 illustrates that the lug tapper at the trailing edge 14 near the shoulder is 12°. The lug tapper angle at the axial leading nose edge 12 and the circumferential inner nose edge 16 is 15° and 10°, respectively. Thus a gap between the lugs at the nose centre is reduced.

[0042] The lug base radius at the arcuate leading edge 8 gradually varies from the nose portion to the shoulder portion 32 in two parts, first from 15 mm to 38 mm and second from 38 mm to 50 mm.

REFERENCE SIGNS

[0043] 2 tread [0044] 3 tread surface [0045] 4 inner surface [0046] 5 first lug [0047] 6 second lug [0048] 8 arcuate leading edge [0049] 10 first lateral tread edge [0050] 12 axial leading nose edge [0051] 14 arcuate trailing edge [0052] 16 substantially circumferential inner nose edge [0053] 20 second lateral tread edge [0054] 30 shoulder portion [0055] 32 nose portion