Airplane tire with zoned tread

Abstract

A pneumatic tire is provided having a tire tread with a ground engaging outer surface. The tread further has a first or center tread zone located on a center or crown portion of the tread and formed from a first rubber compound. Additionally, the tread has a second or shoulder tread zone located axially outward of the first or center tread zone on each lateral end of the tread. The second or shoulder tread zone is formed from a second rubber compound. In one example, the first rubber compound has a G' (at 50% strain) in a range of 1.6 MPa to 1.8 MPa. In another example, the second rubber compound has a G' (at 100% strain) in a range of 800 KPa to 830 KPa.

Description

TECHNICAL FIELD

[0001] The present invention relates to pneumatic tires, and more particularly to high speed heavy load tires, such as high speed heavy load tires used on aircraft. BACKGROUND

[0002] Current tire design drivers for aircraft tires include designing the tire for high wear resistance. Figure 2 A computer simulation of a comprehensive wear model is illustrated that shows the amount of wear from various aircraft activities, such as landing, taxiing, turning. The center portion of the tire tread has the most wear. The outer lateral ends of the tire tread, near the shoulders, also have high wear. The current level of development for high wear tire treads is to select a tread compound with high stiffness or high abrasion resistance in order to improve wear resistance. However, the inventors of the present invention have discovered an improved wear tread that is contrary to the current level of development. SUMMARY

[0003] In a first aspect, the present invention provides a pneumatic tire having a tread with a ground engaging outer surface, the tread having a first tread zone and a second tread zone, wherein the first tread zone includes a center portion of the tread, and the second tread zone is located adjacent to the first tread zone and on each lateral end of the tread, wherein the first tread zone is formed of a first rubber compound, and the second tread zone is formed of a second rubber compound, wherein the first rubber compound has a G' (at 50% strain) in the range of 1.6 MPa to 1.8 MPa.

[0004] In a second aspect, the present invention provides a pneumatic tire having a tread with a ground engaging outer surface, the tread having a first tread zone and a second tread zone, wherein the first tread zone includes a center portion of the tread, and the second tread zone is located adjacent to the first tread zone and on each lateral end of the tread, wherein the first tread zone is formed of a first rubber compound, and the second tread zone is formed of a second rubber compound, wherein the second rubber compound has a G' (at 100% strain) in the range of 800 KPa to 830 KPa.

[0005] DEFINITIONS

[0006] "Tire body" means the tire structure excluding the belt structure, the tread, the undertread, and the sidewall rubber on the plies, but including the beads.

[0007] "Circumferential" means a line or direction running along the circumference of the annular tread surface perpendicular to the axial direction.

[0008] "Cord" means one of the included reinforcing strands that make up a ply in a tire.

[0009] "Equatorial plane" and "EP" mean the plane perpendicular to the axis of rotation of the tire and passing through the center of the tread of the tire.

[0010] "Carcass ply" means a continuous layer of parallel cords coated with rubber.

[0011] "Radial" and "radially" mean directions radially toward or away from the axis of rotation of the tire.

[0012] "Radial ply tire" means a pneumatic tire belted or circumferentially limited in which the carcass ply cords extending from the bead to the bead are laid at a cord angle between 65° and 90° with respect to the equatorial plane of the tire. BRIEF DESCRIPTION OF DRAWINGS

[0013] The application will be described by way of example and with reference to the accompanying drawings in which:

[0014] Figure 1 is a schematic cross-sectional view of a first embodiment of a half of a zoned tire tread according to the application;

[0015] Figure 2 is a computer model plot of tire tread wear indicator versus y coordinate;

[0016] Figure 3 is a computer model plot of relative G' versus shoulder wear;

[0017] Figure 4 is a computer model plot of relative G' versus centerline tread wear; and

[0018] Figure 5 is a computer model plot of overall wear of a tire with three different zoned tread compositions. DETAILED DESCRIPTION

[0019] Figure 1 illustrates a cross-sectional view of a half of a pneumatic tire tread 10 according to the application. The tire is symmetric about a median circumferential plane, such that only a half is illustrated. As shown, the tire tread 10 is for an aircraft tire, although the application is also applicable to other uses, such as truck tires or off-road tires.

[0020] The tire tread 10 defines an outer driving surface 12, which includes a plurality of tread grooves 14, 16 separated by tread blocks or tread strips. The tire tread 10 is segmented and has a first or central tread region 30 formed of a first rubber compound and located at the center or crown portion of the tire tread 10. The tire tread 10 further includes a second or shoulder tread region 40 formed of a second rubber compound. The second tread region 40 is located axially outside the first or central tread region 30, at each lateral end of the tire tread 10. The second tread region 40 extends from the tire tread interface 50 to the shoulder region terminating at the sidewall.

[0021] Figure 2 The illustration shows a computer simulation of a comprehensive wear model, which depicts the amount of wear caused by events such as takeoff, landing taxiing, turning, and braking. Figure 2 As shown, a large increase in wear is observed in the shoulder tread area 40 at the outer end of the tire tread 10.

[0022] Figure 3 The diagram illustrates the shoulder wear of an aircraft tire in relation to high strain G' or R. 2 G' (measured at 50% to 100% strain) at >0.8 is strongly correlated. G' is the dynamic storage modulus and a measure of the viscoelastic properties of a rubber compound at various strain levels. G' can be obtained using a rubber processing analyzer, such as the RPA 2000™ from Alpha Technologies. This measurement is known to those skilled in the art. These measurements are typically performed on raw rubber. For example, using the RPA2000™, strain scans can be performed at 1 Hz at 100°C over a strain range from 1% to 100%.

[0023] Additionally, Figure 3 The figure illustrates the shoulder wear rate for various compounds with different stiffness levels. Figure 3 The illustration shows that the shoulder wear rate is lowest for softer compounds, i.e., the G' value is lower at high strain. In one embodiment, the G' of the second rubber compound used for the shoulder or second tread region 40 is selected to have a G' in the range of 810,000 MPa to 830,000 MPa, and more preferably about 820,000 MPa (at 100% strain). In a second embodiment, the G' of the second rubber compound used for the shoulder or second tread region 40 is selected to have a G' in the range of 1.024 MPa to 1.028 MPa, and more preferably about 1.026 MPa (at 50% strain).

[0024] Figure 4 The figure illustrates the centerline wear rate of the tire tread 10 relative to G' at various strain levels. FromFigure 4 It has been determined that centerline wear is strongly related to G' at 100% strain. For compounds with higher stiffness, i.e., higher G' values (at 100% strain), centerline wear is reduced. Thus, for the first or center tread zone 30, it is preferred that the G' (100%) of the first rubber compound be in the range of 1.2 MPa to 1.4 MPa and more preferably about 1.3 MPa. Additionally, for the first or center tread zone 30, it is preferred that the G' (at 50% strain) of the first rubber compound be in the range of 1.6 MPa to 1.8 MPa and more preferably about 1.7 MPa.

[0025] Figure 5 The overall wear rate of the tire tread 10 using the first and second tread zones 30 and 40 is illustrated for different types of compounds. Thus, the tread zoning improves the wear balance of the tire tread 10 while slightly improving the centerline tread wear.

[0026] Thus, to improve the overall wear rate of the tire tread 10, it is desirable to have a first or center tread zone 30 formed of a first rubber compound having a G' (50%) that is at least 150% of the G' (at 50% strain) of the second rubber compound and more preferably at least 170% of the G' (at 50% strain) of the second rubber compound.

[0027] The first rubber compound is selected to have greater stiffness than the second rubber compound in order to provide greater wear resistance to the tread along the first or center tread zone 30 and the second rubber compound provides a softer compound to the tread that reduces shoulder wear. The interface 50 or dividing line between the first and second tread zones 30 and 40 is determined from modeling analysis such as that shown in Figure 2 Figure 5 As shown in the modeling analysis shown in Figure 5 As shown in the modeling analysis shown in

[0028] Variations of the application are possible in light of the description of the application provided herein. While certain representative embodiments and details have been shown for purposes of illustrating the application, it will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the application. It will be understood, therefore, that changes and modifications can be made within the scope of the application as defined by the appended claims and the following.

Claims

1. A pneumatic tire, the pneumatic tire having a tread with a ground-contacting outer surface, the tread having a first tread area and a second tread area, wherein, The first tread area includes a central portion of the tread, and the second tread area is positioned adjacent to the first tread area and on each lateral end of the tread, wherein the first tread area is formed of a first rubber compound, and the second tread area is formed of a second rubber compound, wherein the first rubber compound has a G' in the range of 1.6 MPa to 1.8 MPa at 50% strain; The second rubber compound has a G' in the range of 1.02 MPa to 1.03 MPa at 50% strain; Wherein, the first rubber compound has a G' at 50% strain that is at least 150% of the second rubber compound's G' at 50% strain.

2. The pneumatic tire according to claim 1, wherein, The first rubber compound has a G' at 50% strain that is at least 170% of the G' of the second rubber compound at 50% strain.

3. The pneumatic tire according to claim 1, wherein, The axial width of the first tread area is in the range of 50% to 70% of the width of the tread.

4. A pneumatic tire having a tread with a ground-contacting outer surface, the tread having a first tread area and a second tread area, wherein, The first tread region includes a central portion of the tread, and the second tread region is positioned adjacent to the first tread region and on each lateral end of the tread, wherein the first tread region is formed of a first rubber compound, and the second tread region is formed of a second rubber compound, wherein the second rubber compound has a G' in the range of 800 kPa to 830 kPa at 100% strain.

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