Crown For Aircraft Tire

Abstract

Tire for an aeroplane and, in particular, the crown thereof which comprises a tread (1), a textile crown reinforcement (2) and a textile carcass reinforcement (4). In order to optimize the number of landings, in the equatorial plane, the thickness (E1) of the tread is at least equal to 1.1 times the thickness of the working reinforcement and the thickness (E5) of the carcass is at least equal to 1.5 times the thickness (E3) of the working reinforcement, the reinforcing elements of the working layers (31, 32, 33) having a tenacity at least equal to 90 cN/tex.

Claims

1. Tire for an aeroplane, comprising: a tread having a centre thickness that is measured in the equatorial plane, passing through the middle of the tread and perpendicular to the axis of rotation of the tire, between the radially outermost point of the tread and the radially outermost point of a crown reinforcement radially on the inside of the tread; the crown reinforcement comprising at least one working reinforcement; the working reinforcement comprising at least one working layer that has an axial width, measured over the working layer having the greatest axial width, at least equal to ⅔ of the maximum axial width of the tire, and having a centre thickness in the equatorial plane that is measured between the radially outermost point of the radially outermost working layer and the radially innermost point of the radially innermost working layer; the working layers comprising textile reinforcing elements; a carcass reinforcement, radially on the inside of the working reinforcement, comprising at least one carcass layer and having a centre thickness in the equatorial plane that is measured between the radially outermost point of the radially outermost carcass layer and the radially innermost point of the radially innermost carcass layer; the carcass layers comprising textile reinforcing elements; a reinforcement that is formed by the working reinforcement and the carcass reinforcement and has a centre thickness in the equatorial plane that is measured between the radially outermost point of the radially outermost working layer and the radially innermost point of the radially innermost carcass layer, wherein the centre thickness of the tread is at least equal to 1.1 times the centre thickness of the reinforcement formed by the working reinforcement and the carcass reinforcement, wherein the centre thickness of the tread is at least equal to 1.5 times the centre thickness of the working reinforcement, and wherein the reinforcing elements of the working layers have a tenacity at least equal to 90 cN/tex.

2. The airplane tire according to claim 1, wherein the centre thickness of the tread is at least equal to 4.2 times the centre thickness of the carcass reinforcement, and wherein the reinforcing elements of the carcass layers have a tenacity at least equal to 90 cN/tex.

3. The airplane tire according to claim 1, a straight line that passes through the centre of the tire, at the intersection of the equatorial plane and the axis of rotation, and through the point of the widest working layer, said point being positioned at an axial distance from the equatorial plane equal to 0.9 times the axial half-width of said layer, being defined as the measuring line for the shoulder thicknesses, the tread having a shoulder thickness measured between the radially outermost point, positioned on the measuring line, of the tread and the radially outermost point, positioned on the measuring line, of the radially outermost crown layer, the reinforcement formed by the working reinforcement and the carcass reinforcement having a shoulder thickness between the radially outermost point, positioned on the measuring line, of the radially outermost crown layer, and the radially innermost point, positioned on the measuring line, of the radially innermost carcass layer, wherein the shoulder thickness of the tread is at least equal to 1.2 times the shoulder thickness of the reinforcement.

4. The airplane tire according to claim 1, the carcass reinforcement having a shoulder thickness, measured between the radially outermost point, positioned on the measuring line, of the radially outermost carcass layer and the radially innermost point, positioned on the measuring line, of the radially innermost carcass layer, wherein the shoulder thickness of the tread is at least equal to 4.2 times the shoulder thickness of the carcass reinforcement.

5. The airplane tire according to claim 1, wherein the working layers comprise mutually parallel reinforcing elements that form an angle of between +20° and −20° with the circumferential direction.

6. The airplane tire according to claim 1, wherein the carcass layers comprise mutually parallel reinforcing elements that form an angle of between 80° and 100° with the circumferential direction.

7. The airplane tire according to claim 1, wherein the reinforcing elements of the working layers have a tenacity at least equal to 110 cN/tex.

8. The tire according to claim 1, wherein the reinforcing elements of the working layers consist of aromatic polyamides or a combination of aliphatic polyamides and aromatic polyamides.

9. The airplane tire according to claim 1, wherein the reinforcing elements of the carcass layers have a tenacity at least equal to 110 cN/tex.

10. The airplane tire according to claim 1, wherein the reinforcing elements of the carcass layers consist of aromatic polyamides or a combination of aliphatic polyamides and aromatic polyamides.

11. The tire according to claim 1, wherein the crown reinforcement comprises at least one protective reinforcement radially on the inside of the tread and radially on the outside of the working reinforcement which comprises at least one protective layer that comprises metal or textile reinforcing elements.

Description

[0057] The features and other advantages of the invention will be understood better with the aid of FIGS. 1 to 4, said figures not being shown to scale but in a simplified manner so as to make it easier to understand the invention.

[0058] FIG. 1: crown of an aeroplane tire in a meridian plane and the thicknesses of the tread, of the working reinforcement, of the carcass reinforcement and of the reinforcement

[0059] FIG. 2: measurement of the centre thickness of the tread in a meridian plane

[0060] FIG. 3: measurement of the centre thicknesses of the working reinforcement and of the carcass reinforcement in a meridian plane

[0061] FIG. 4: measurement of the different shoulder thicknesses in a meridian plane

[0062] FIG. 1 shows a meridian section, i.e. a section in a meridian plane, of the crown of a tire according to one embodiment of the invention comprising a tread 1, a crown reinforcement 2 radially on the inside of the tread 1, comprising a protective layer 21 radially on the inside of the tread 1 and a working reinforcement 3 radially on the inside of the protective layer, a radial carcass reinforcement 4 radially on the inside of the working reinforcement 3. The reinforcement 5 consists of the carcass reinforcement 4 and the working reinforcement 3. The respective radial, axial and circumferential directions are the directions ZZ′, YY′ and XX′. The equatorial plane XZ is defined by the radial direction ZZ′ and the circumferential direction XX′. The figure also shows the position of the centre thickness E1 of the tread, the centre thickness E3 of the working reinforcement, the centre thickness E4 of the carcass reinforcement and the centre thickness E5 of the reinforcement.

[0063] The working reinforcement 3 is made up of several working layers. The axial width LT of the widest working layer 32 is the axial distance between its axial ends F2 and F′2 and is at least equal to two-thirds of the maximum axial width L1 of the tire. The maximum axial width L1 of the tire is measured at the sidewalls, with the tire mounted on its rim and lightly inflated, i.e. inflated to a pressure equal to 10% of the recommended nominal pressure.

[0064] FIG. 2 shows the principle of measuring the centre thickness E1 of the tread between the point Z1 defined as belonging to the equatorial plane XZ and being the radially outermost point of the tread and the point Z2 on the equatorial plane XZ that is determined by its intersection with the spline passing through the radially outermost points of the reinforcing elements of the radially outermost layer 21 of the crown reinforcement 2.

[0065] FIG. 3 shows the principle of measuring:

[0066] the centre thickness E5 of the reinforcement, between the points Z3 and Z6, [0067] the centre thickness E3 of the working reinforcement, between the points Z3 and Z4, [0068] the centre thickness E4 of the carcass reinforcement, between the points Z5 and Z6.

[0069] Z3 is defined as being the intersection of the equatorial plane XZ and the spline passing through the radially outermost points of the reinforcing elements of the radially outermost layer 31 of the working reinforcement 3. Z4 is defined as being the intersection of the equatorial plane XZ and the spline passing through the radially innermost points of the reinforcing elements of the radially innermost layer 32 of the working reinforcement 3. Z5 is defined as being the intersection of the equatorial plane XZ and the spline passing through the radially outermost points of the reinforcing elements of the radially outermost layer 41 of the carcass reinforcement 4. Z6 is defined as being the intersection of the equatorial plane XZ and the spline passing through the radially innermost points of the reinforcing elements of the radially innermost layer 42 of the carcass reinforcement 4.

[0070] FIG. 4 shows the principle of measuring the shoulder thickness E1′ of the tread, measured on the straight line D, the measuring line at the shoulder, passing through the centre of the tire and passing through the point Z7 of the widest working layer, said point Z7 being situated at an axial distance of 90% of its half-width LT/2. The radius from the centre of the closest reinforcing element will be taken as the precise radius of Z7. E1′ is measured between Z8 and Z9. Z8 is defined as being the radially outermost point of the tread belonging to D. Z9 is defined as being the point of intersection of D and the spline passing through the radially outermost points of the reinforcing elements of the radially outermost crown layer at the shoulder, in this case, the radially outermost crown layer at the shoulder is also the radially outermost working layer 31 at the shoulder.

[0071] FIG. 4 also shows the principle of measuring the shoulder thickness E5′ of the reinforcement measured on the straight line D. E5′ is measured between the point of intersection of D and the spline passing through the radially outermost points of the reinforcing elements of the radially outermost working layer 31 at the shoulder, in this case coincident with Z9, and Z11. Z11 is defined as being the point of intersection of D and the spline passing through the radially innermost points of the reinforcing elements of the radially innermost carcass layer 42.

[0072] FIG. 4 also shows the principle of measuring the shoulder thickness E4′ of the carcass reinforcement measured on the straight line D. E4′ is measured between Z10 and Z11. Z10 is defined as being the point of intersection of D and the spline passing through the radially outermost points of the reinforcing elements of the radially outermost carcass layer 41.

[0073] The inventors developed the invention, according to one embodiment, for an aeroplane tire of size 46×17R20, the use of which is characterized by a nominal pressure equal to 15.3 bar, a nominal static load equal to 20 473 daN, and a maximum reference speed of 360 km/h.

[0074] The reference tire and the tire produced in accordance with the invention have concave crowns within the meaning of the patent WO 2010000747.

[0075] The change from nylon working and carcass reinforcements to hybrid working and carcass reinforcements makes it possible to reduce the number of working layers from 10 to 7 and the number of carcass layers from 6 to 3, respectively.

[0076] The invention was carried out with a working reinforcement made up of 6 working layers, the reinforcing elements of which are of the hybrid type. The radially internal working layer has an axial width of 300 mm, i.e. 0.75 times the maximum axial width of the tire. The width of concavity of said radially internal working layer is 160 mm and the amplitude of concavity is 6 mm. The carcass reinforcement is made up of 3 carcass layers, the reinforcing elements of which are hybrid.

[0077] A hoop reinforcement is also used. The latter consists of a hooping layer, the reinforcing elements of which are of the hybrid type. For the working and hooping layers, the hybrid reinforcing elements used consist of two spun aramid yarns of 330 tex each and one spun nylon yarn of 188 tex. The diameter of the hybrid reinforcing element obtained is 1.11 mm, its count is 950 tex, its twist is 230 tpm, its elongation under 50 daN of force is 5.5% and its breaking force is 110 daN, i.e. a tenacity of 116 cN/tex.

[0078] For the carcass layers, the hybrid reinforcing elements used consist of two spun aramid yarns of 330 tex each and one spun nylon yarn of 188 tex. The diameter of the hybrid reinforcing element obtained is 1.1 mm, its count is 980 tex, its twist is 270 tpm, its elongation under 50 daN of force is 5.5% and its breaking force is 110 daN, i.e. a tenacity of 112 cN/tex. Further hybrid reinforcements could also be used. It is notably conceivable to use reinforcements with a different twist, or even reinforcements having a different count or a different number of each spun yarn.

[0079] The decrease in the maximum temperature on the equatorial plane makes it possible, while maintaining the endurance performance of the tire, to increase the centre thickness E1 of the tread from 16 mm to 18 mm, i.e. an increase in the thickness E1 of 12.5% and an increase in the volume of rubber to be used of 30%. A person skilled in the art will associate this increase in the thickness of the tread with an at least equivalent increase in the number of landings.

[0080] The decrease in the maximum temperature at the axial ends of the working layers makes it possible, while maintaining the endurance performance of the tire, to increase the shoulder thickness E1′ of the tread from 17.5 mm to 19.5 mm, i.e. an increase of 11%. A person skilled in the art will associate this increase in the thickness of the tread with an at least equivalent increase in the number of kilometres covered when taxiing.

[0081] In the reference tire, in the equatorial plane, the centre thickness E1 of the tread between the radially outer point of the tread and the radially outermost crown layer 21 is at most equal to 0.9 times the centre thickness E5 of the reinforcement between the radially outermost working layer 31 and the radially innermost crown layer 42, is at most equal to 1.2 times the centre thickness E3 of the working reinforcement between the radially outermost working layer 31 and the radially innermost working layer 32, and is at most equal to 3 times the centre thickness E4 of the carcass reinforcement E4 between the radially outermost carcass layer 41 and the radially innermost carcass layer 42.

[0082] In the tire according to the invention, in the equatorial plane, the centre thickness E1 of the tread is equal to 1.24 times the centre thickness E5 of the reinforcement, is equal to 1.64 times the centre thickness E3 of the working reinforcement, and is equal to 4.5 times the centre thickness E4 of the carcass reinforcement.

[0083] In the reference tire, at the shoulder, on the measuring line D, the shoulder thickness E1′ of the tread is at most equal to 1 time the shoulder thickness E5′ of the reinforcement between the radially outermost working layer and the radially innermost carcass layer, and is at most equal to 3 times the shoulder thickness E4′ of the carcass reinforcement between the radially outermost carcass layer and the radially innermost carcass layer.

[0084] In the tire according to the invention, on the straight line D, the shoulder thickness E1′ of the tread is equal to 1.26 times the shoulder thickness E5′ of the reinforcement and is equal to 4.88 times the shoulder thickness E4′ of the carcass reinforcement.

[0085] The estimate of the improvement in landing wear performance and rolling wear performance is at least 30% in correlation with the increase in the volume of rubber to be used.