GB1603058A

GB1603058A - High load bearing capacity pneumatic tyre

Info

Publication number: GB1603058A
Application number: GB17456/78A
Authority: GB
Original assignee: Uniroyal GmbH
Current assignee: Uniroyal GmbH
Priority date: 1977-05-03
Filing date: 1978-05-03
Publication date: 1981-11-18
Also published as: FR2389503B1; JPS53136207A; BE866679A; AU516618B2; AU3568378A; CA1086619A; IT7868011A0; SE7805046L; DE7713981U1; IT7853275V0; FR2389503A1

Description

(54) HIGH LOAD BEARING CAPACITY PNEUMATIC TIRE (71) We, UNIROYAL GMBH (formerly UNIROYAL AG), of D-5100 Aachen 1, Huettenstrasse 7, Federal Republic of Germany, a corporation organised under the laws of the District Court of Aachen, Federal Republic of Germany, do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to pneumatic tires and more particularly to a heavy duty, high-load capacity pneumatic tire for trucks or other large size vehicles.

One known high load capacity tire employs a reinforcement comprising a folded belt ply having a cord angle of 15" enclosing an unfolded belt ply having a cord angle of 22". Another unfolded belt ply having a cord angle of 18 is disposed between the folded free ends of the 15 ply, all plies being made of steel cord. This reinforcement is particularly stiff at the belt edges and at the shoulder areas.

Some tires when mounted to a heavy vehicle, can usually be operated without damage for an extended period of time at a speed of 120-130 kilometers per hour (75 to 81.25 miles per hour). However. the tire carcass undergoes considerable deflection between the sidewall areas of maximum width. Consequently there is a relatively low radial elevation of the tire tread above the rim, usually lower than that of a standard pneumatic tire for heavy vehicles which often results in pronounced wear of the tire in the shoulder area.

In large, heavy duty. high load bearing capacity pneumatic tires it is desirable to keep the tire cross-section substantially flat not only during its manufacture but also when it is inflated to normal operating pressure.

According to the present invention a heavy duty, high load bearing capacity pneumatic tire comprises a tread, a radial carcass having at least one cord ply, and a multi-ply belt-like reinforcement disposed between the tread and the carcass, said reinforcement including a plurality of unfolded radially internal plies on the crown area of the carcass and an unfolded, radially external, axially central fettering ply formed with parallel steel cords and being of lesser axial extent than the radially internal plies for firmly clamping the radially internal plies to the crown area of the carcass, the radially internal plies each having parallel cords making a bias angle of from 60 to 32 with respect to the mid-circumferential plane of the tread and the cords of the or each adjacent pair of radially internal plies being arranged to intersect, and wherein the bias angle of the cords of the fettering ply with respect to the mid-circumferential plane of the tread is from 5 to 15 , the fettering ply maintaining the crown area of the carcass in a substantially flat shape in an uninflated condition and when the tire is inflated to normal operating pressures. This belt construction leads, during manufacture, to a tire of substantially flat cross-section that can provide improved wear characteristics particularly in the shoulder area of the tire.

The belt-like reinforcement may conveniently include two to four (preferably three) unfolded radially internal plies, which may have cords that are desirably of steel and/or Aramide fibre.

Referring now to the drawing the pneumatic tire is generally indicated by reference number 1 and a central circumferential plane of the tire 1 is indicated by the reference letter A. The intersection between the central circumferential plane A and the tire tread defines a central circumferential line of the tread.

The tire 1 includes a radial carcass 2 preferably made of steel cords. Although the carcass 2 is shown to be of single ply construction it is also feasible to use a carcass having more than one ply. The carcass 2, in its sidewall areas, is covered by sidewall rubber plies 3 extending bilaterally into the shoulder areas 6 and 7 of a tread 5.

The inner area of the tire is designated by the reference number 4.

A belt-like reinforcement 8 is disposed between the tread 5 and the crown area of the carcass 2 and bears upon the carcass 2 along both sides of the central circumferential plane A.

A pair of adhesive rubber cushions 11 and 12 are arranged beneath the marginal areas of the belt-like reinforcement 8.

The belt-like reinforcement 8 comprises two to four unfolded radially internal plies of steel or Aramide cord layered one upon the other, three such plies 13, 14 and 15 being shown in the drawling. The cords in each of the plies 13, 14 an 15 are parallel within the respective and and make an angle of between 1 and 32", preferably between 18 and 24 with the circumferential center line of the tread. However, bias angles of the cords in each pair of adjacent radially internal plies lie in different quadrants with respect to coordinate axes, one such axis being the circumferential centre line of the tread, so that the cords in each such pair intersect.

It should be noted that the plies 13, 14 and 15 can each be formed with either all steel cord or all Aramide cord, although it is not necessary for all the plies to have cords of the same material.

A fettering ply 16 made of steel cord is layered directly onto the ply 15 and covers the axially central area of the plies 13, 14 and 15 and is of lesser axial extent than the plies 13, 14 and 15. The ply 16 thus clamps the central area of the plies 13, 14 and 15 to the carcass 2, the fettering effect being achieved by arranging the parallel cords in the ply 16 at a bias angle of from 5 to 150 with the circumferential center line of the tread. The bias angles of the cords in the fettering ply and of the cords in the immediately underlying ply 15 may lie in the same or different quadrants with respect to coordinate axes as aforesaid.

The plies 13, 14 and 15 are shown as being of different axial extent, the middle ply 14 having the greatest axial extent and the outermost ply 15 having a lesser axial extent than the innermost ply 13. However, this relationship between the axial extents of the three radially inner plies, is not essential.

The plies are shown in the drawing as having the same radial thickness, but this again is not essential.

It has been found that upon vulcanization of the disclosed tire construction and also upon inflating the tire to normal operating pressure the crown area of the carcass has a low radius of curvature and retains a substantially flat cross-sectional shape. The flatness extends to a larger area of the unfolded belt plies and carcass crown than is encompassed by the fettering ply. The fettering ply thus permits a firm and durable application of the unfolded belt plies to the crown area of the carcass.

Thus the provision of the steel cord fettering ply of lesser axial extent and of lesser cord angle than the radially internal plies enables large size and high load bearing capacity pneumatic tires to be constructed with crowns which are crosssectionally substantially flat in a simple efficient manner. Since the shoulder crosssection is substantially smaller than corresponding shoulder areas of conventional pneumatic tires for trucks it generates less interior heat during operation, resulting in reduced wear of the shoulder.

WHAT WE CLAIM IS: 1. A heavy duty, hith load bearing capacity pneumatic tire comprising a tread, a radial carcass having at least one cord ply, and a multi-ply belt-like reinforcement disposed between the tread and the carcass, said reinforcement including a plurality of unfolded radially internal plies on the crown area of the carcass and an unfolded, radially external, axially central fettering ply formed with parallel steel cords and being of lesser axial extent than the radially internal plies for firmly clamping the radially internal plies to the crown area of the carcass, the radially internal plies each having parallel cords making a bias angle of from 16 to 32 with respect to the mid-circumferential plane of the tread and the cords of the or each adjacent pair of radially internal plies being arranged to intersect, and wherein the bias angle of the cords of the fettering ply with respect to the mid-circumferential plane of the tread is from 5 to 150, the fettering ply maintaining the crown area of the carcass in a substantially flat shape in an uninflated condition and when the tire is inflated to normal operating pressures.

2. A tire as claimed in claim 1, in which the radially internal plies comprise steel cords.

3. A tire as claimed in claim 1, in which the radially internal plies comprise cords of the material known commercially as Aramide.

4. A tire as claimed in any preceding claim, in which there are three radially internal plies.

5. A tire as claimed in claim 3, in which the radially internal plies are of differing axial extents.

6. A tire as claimed in claim 5, in which the middle ply of the three radially internal

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. preferably made of steel cords. Although the carcass 2 is shown to be of single ply construction it is also feasible to use a carcass having more than one ply. The carcass 2, in its sidewall areas, is covered by sidewall rubber plies 3 extending bilaterally into the shoulder areas 6 and 7 of a tread 5. The inner area of the tire is designated by the reference number 4. A belt-like reinforcement 8 is disposed between the tread 5 and the crown area of the carcass 2 and bears upon the carcass 2 along both sides of the central circumferential plane A. A pair of adhesive rubber cushions 11 and 12 are arranged beneath the marginal areas of the belt-like reinforcement 8. The belt-like reinforcement 8 comprises two to four unfolded radially internal plies of steel or Aramide cord layered one upon the other, three such plies 13, 14 and 15 being shown in the drawling. The cords in each of the plies 13, 14 an 15 are parallel within the respective and and make an angle of between 1 and 32", preferably between 18 and 24 with the circumferential center line of the tread. However, bias angles of the cords in each pair of adjacent radially internal plies lie in different quadrants with respect to coordinate axes, one such axis being the circumferential centre line of the tread, so that the cords in each such pair intersect. It should be noted that the plies 13, 14 and 15 can each be formed with either all steel cord or all Aramide cord, although it is not necessary for all the plies to have cords of the same material. A fettering ply 16 made of steel cord is layered directly onto the ply 15 and covers the axially central area of the plies 13, 14 and 15 and is of lesser axial extent than the plies 13, 14 and 15. The ply 16 thus clamps the central area of the plies 13, 14 and 15 to the carcass 2, the fettering effect being achieved by arranging the parallel cords in the ply 16 at a bias angle of from 5 to 150 with the circumferential center line of the tread. The bias angles of the cords in the fettering ply and of the cords in the immediately underlying ply 15 may lie in the same or different quadrants with respect to coordinate axes as aforesaid. The plies 13, 14 and 15 are shown as being of different axial extent, the middle ply 14 having the greatest axial extent and the outermost ply 15 having a lesser axial extent than the innermost ply 13. However, this relationship between the axial extents of the three radially inner plies, is not essential. The plies are shown in the drawing as having the same radial thickness, but this again is not essential. It has been found that upon vulcanization of the disclosed tire construction and also upon inflating the tire to normal operating pressure the crown area of the carcass has a low radius of curvature and retains a substantially flat cross-sectional shape. The flatness extends to a larger area of the unfolded belt plies and carcass crown than is encompassed by the fettering ply. The fettering ply thus permits a firm and durable application of the unfolded belt plies to the crown area of the carcass. Thus the provision of the steel cord fettering ply of lesser axial extent and of lesser cord angle than the radially internal plies enables large size and high load bearing capacity pneumatic tires to be constructed with crowns which are crosssectionally substantially flat in a simple efficient manner. Since the shoulder crosssection is substantially smaller than corresponding shoulder areas of conventional pneumatic tires for trucks it generates less interior heat during operation, resulting in reduced wear of the shoulder. WHAT WE CLAIM IS:

1. A heavy duty, hith load bearing capacity pneumatic tire comprising a tread, a radial carcass having at least one cord ply, and a multi-ply belt-like reinforcement disposed between the tread and the carcass, said reinforcement including a plurality of unfolded radially internal plies on the crown area of the carcass and an unfolded, radially external, axially central fettering ply formed with parallel steel cords and being of lesser axial extent than the radially internal plies for firmly clamping the radially internal plies to the crown area of the carcass, the radially internal plies each having parallel cords making a bias angle of from 16 to 32 with respect to the mid-circumferential plane of the tread and the cords of the or each adjacent pair of radially internal plies being arranged to intersect, and wherein the bias angle of the cords of the fettering ply with respect to the mid-circumferential plane of the tread is from 5 to 150, the fettering ply maintaining the crown area of the carcass in a substantially flat shape in an uninflated condition and when the tire is inflated to normal operating pressures.

plies is of greater axial extent than each of the other radially internal plies.

7. A tire as claimed in claim 6, in which the outermost ply of the three radially internal plies is of lesser axial extent than the innermost ply of the three radially internal plies.

8. A tire as claimed in any preceding claim, in which the bias angle of the radially internal plies is within the range of from 18 to 240.

9. A tire as claimed in any preceding claim, in which the tire has sidewalls joined to respective opposite end portions of the tread, and the respective ones of a pair of adhesive rubber cushions are arranged at each of the end portions of the tread beneath the marginal areas of the reinforcing belt.

10. A pneumatic tire substantially as described herein with reference to, and as illustrated in, the accompanying drawing.