Resilient tires and wheels – Tires – resilient – Pneumatic tire or inner tube
Reexamination Certificate
1998-07-06
2001-12-25
Johnstone, Adrienne C. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Pneumatic tire or inner tube
C152S539000, C152S546000, C152S548000
Reexamination Certificate
active
06332486
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a radial tire, more particularly to a radial tire with improved riding comfort and driving stability.
2. Description of the Prior Art
In general, the performance of a radial tire may be improved if the tread of the tire is very stiff. However, this reduces driving stability because the radial carcass cords of a tire tend to weaken the lateral stiffness of the sidewall of the tire. In such cases, the driving stability may be improved in a number of ways, for example, by changing the material and the number of the carcass cords, by changing the rubber material of the sidewall, by supplementing cord layers to strengthen the bead or by redesigning the mold profile of the tire. The driving stability may be improved by modifying the beadfiller profile.
More recently, driving stability has been improved by raising the height of the beadfiller or lowering the cross-sectional height of the beadfiller by using a light beadfiller. However, this may cause the lateral stiffness and the vertical stiffness of the tire to increase thereby adversely affecting riding comfort.
Japanese Patent Laid-Open No. 55-110604 published in 1980 and Japanese Patent Laid-Open No. 61-303392 published in 1986 seek to address these problems. Therein, the ratio of USH to SH (the ratio of upper cross-sectional height to cross-sectional height upon mounting the radial tire on the rim and filling to normal internal pressure) of the carcass profile was increased to enhance both riding comfort and steering stability.
Whilst prior art techniques may, in general, be able to improve certain characteristics of a radial tire, they may at the same time adversely affect other important features such as driving stability and cornering forces or steering stability. A further drawback is that in order to improve the specific performance level of a tire, a tire designer has to design a modified carcass form appropriate for this specific performance, and also consider both the form and hardness of the beadfiller to keep the desired shape of the carcass.
BRIEF SUMMARY OF THE INVENTION
The present invention seeks to provide a radial tire having an overall improved performance over prior art radial tires. Thus, the carcass profile and beadfiller profile may be manipulated together with the cross-sectional width of the tire to enhance the performance of existing prior art radial tires. Properties such as driving stability and riding comfort are therefore enhanced but not at the expense of other properties.
Thus viewed from one aspect, the present invention provides a radial tire capable of being mounted on a rim and filled to normal internal pressure such that the ratio of upper cross-sectional height (USH) to cross-sectional height(SH)is within the range 0.5 to 0.59; the ratio of lower cross-sectional height (LSH) to cross-sectional height (SH) is in the range of 0.40 to 0.50; the rim width is more than 1.40×measuring rim width and less than 1.45×measuring rim width; the aspect ratio is less than 0.65; the beadfiller height (BH) is more than 0.224×SH; the angle between the tangent to the carcass line at a bead upper point (B) and the line extending in parallel with the rotational axis of the tire is less than 45°.
The term “measuring rim width(MRW)” used herein means the rim of the optimum condition being specified according to a tire size, which can be achieved when the tire is mounted on the rim, and which is shown in YEAR BOOK of TRA(Tire Rim Association). That is, when designing a tire, rim width and measuring rim width may be different.
The radial tire according to the present invention has many advantages over that of the prior art. Some of these are discussed by way of example hereinafter. It is able to simultaneously enhance stiffness, riding comfort and driving stability without adversely affecting other aspects of the tire performance. This is achieved by modifying the radial carcass ply and outside form, reducing the cross-sectional center of the tire, making the cross-sectional width of the tire as wide as possible, using a light beadfiller, and sloping the beadfiller more than in the prior art.
To achieve these advantages, the profile of the radial tire is manipulated under conditions in which the radial tire is mounted and filled with normal inner pressure. The ratio of USH to SH and that of LSH to SH is within the range 0.50 to 0.59 and 0.40 to 0.50 respectively. The rim width is more than 1.40×MRW and less than 1.45×MRW. The aspect ratio is less than 0.65, the angle between the tangent to the carcass line at a bead upper point (B) and the line extending in parallel with the rotation axis of the tire is less than 45°. The beadfiller height (BH) is greater than 0.224×SH.
Preferably, the Shore A hardness of the beadfiller is greater than 85°.
Preferably, xb (the component of the x axis of the bead upper point B) is greater than the measuring rim width×0.5 and particularly preferably is within the range measuring rim width +5-10 mm.
REFERENCES:
patent: 4513802 (1985-04-01), Togashi et al.
patent: 4867218 (1989-09-01), Asano et al.
patent: 5178716 (1993-01-01), Hanada et al.
patent: 55110604 (1980-08-01), None
patent: 58161616 (1983-09-01), None
patent: 5948204 (1984-03-01), None
patent: 6060003 (1985-04-01), None
patent: 6060004 (1985-04-01), None
patent: 6060005 (1985-04-01), None
patent: 61222801 (1986-10-01), None
patent: 08142601 (1996-06-01), None
patent: 08142602 (1996-06-01), None
Ahn Myeong Hun
Kim Hwi Joong
Kim Keun Woo
Kim Kyun Ok
Kim Yong Hee
Hankook Tire Manufacturing CO LTD
Johnstone Adrienne C.
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