Resilient tires and wheels – Tires – resilient – Anti-skid devices
Reexamination Certificate
1999-08-12
2002-07-09
Maki, Steven D. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Anti-skid devices
C152S209800, C152S209140, C152S209160, C152S210000, C152S456000
Reexamination Certificate
active
06415837
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a pneumatic tire for multiple-track vehicles.
RELATED TECHNOLOGY
Pneumatic tires having an asymmetrical cross section are standard equipment on multiple-track vehicles. A wide variety of tire sizes having different cross-sectional shapes regarding height-to-width ratios are used. In addition, there is a tendency to use tire cross-sectional shapes in which the height-to-width ratio (aspect ratio) is relatively small, which gives the tire a sporty look. An extreme example of this is racing car tires, which resemble rollers and have a very wide, almost flat tread. As a result, the contact area between the tire and the road is very large and, as the wheel load increases, greater longitudinal and lateral forces can be transferred.
The magnitude of the lateral forces that can be transferred is also dependent on the camber of the wheel in question and, in multiple-track wheeled vehicles, especially special-purpose vehicles known as “Kurvenleger” (three-wheeled vehicles that behave like two-wheeled vehicles when cornering), and also in production vehicles, this is utilized to good effect in that wheel suspensions are designed so that during jouncing the camber becomes negative, and combined with the increasing wheel load during cornering this results in greater transferable lateral guide forces for the wheels on the outside of the curve.
However, in conventional wheel suspensions the feasible negative camber range is very narrow, especially as, in the case of very wide sport tires, changes of this kind in the camber are undesirable in terms of the tires and are not particularly useful in terms of transferable guide forces, because, in the case of a tread with an essentially flat cross section, as the deviation from zero camber increases, the size of the contact area between the tire and the ground surface diminishes.
A pneumatic tire is described in Austrian Patent No. 255 919. The tire is asymmetrical in cross section and is designed for wheels where the camber is kept essentially constant via wheel control as part of the vehicle's basic design. The goal is to achieve better driving characteristics and tire life because the tire is rounded in the shoulder area adjacent to the outside of the tire, in conjunction with the fact that the tread pattern varies across the tire's cross section and/or the tread design varies with a view to achieving higher friction values or greater abrasion resistance. To this end, the largely flat tread section that extends to the inside of the wheel has a pronounced tread pattern for increased grip and includes abrasion-resistant tread material for high running performance in straight-line travel. By contrast, the rounded tread in the section adjacent to the outside of the wheel has a less pronounced tread pattern and includes tread material having a high friction value. This constitutes a good compromise in terms of a tire's running and driving characteristics and its wear resistance.
A tire having an asymmetrical cross section in which the surface outline extending to the outside of the wheel has a slightly reduced diameter, which, when used with a constant-camber wheel suspension designed with negative camber, results in improved running characteristics along with reduced wear, is described in European Patent Application No. 0 607 784 A1.
Furthermore, pneumatic tires for wheels of multiple-track vehicles in which the sidewalls of the tire are of different heights, the outline of the tread being essentially symmetrical and flat, and the height of the tire sidewall on the inside of the wheel being smaller than the tire wall on the outside of the wheel, and accordingly the rim on the inside of a wheel having a larger diameter than the rim on the outside of the wheel, are described in U.S. Pat. No. 3,974,870, French Patent No. 2 200 122, and European Patent Application No. 0 607 784 A1.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a pneumatic tire for wheels of multiple-track vehicles which, even if the tire is fairly wide and the vehicle is cornering, allows such a large contact area between a given tire and the ground that, in combination with increased wheel load during cornering, camber-related lateral forces which are well above the lateral forces that can be transferred with zero camber can be transferred, and allows different areas of the tread to be used in response to different driving and road conditions. The present invention provides a pneumatic tire for multiple-track vehicles, in particular motor vehicles, having a tread that forms the circumference of the tire and transitions into the sidewalls of the tire via laterally adjacent tire shoulders, the sidewalls extending radially inwards to beads that are attachable to the wheel rim, the tire being asymmetrical in cross section and the tread of the tire having a nearly flat tread section which extends from one sidewall area and transitions into a narrower convex tread section that extends radially inward to the other sidewall area, characterized in that the convex tread section (
9
) is assigned to the inside of the wheel and in the case of a negatively cambered wheel (
1
) forms the load-bearing tread section (
9
) with respect to the road (
11
).
Thanks to the asymmetrical design of the tire according to the present invention, the tire can be optimized to meet the requirements of driving in a straight line and normal driving, and also can be used in combination with an active camber control system and/or a closed-loop camber control system that allows one to convert the changes in wheel load associated with cornering in the form of increases in wheel load on the wheel on the outside of the curve into corresponding lateral guide forces, and when driving in a straight line it is possible to respond to specific circumstances such as winter driving by using a different section of the tread, so that as a result driving safety, including driving safety in extreme situations, can be improved.
In an embodiment according to the present invention, the contact area between a given tread and the road for the flat tread section when driving straight can be roughly equal to that for the convex tread section during cornering. In conjunction with adjusting the camber by an amount up to about 25°, it is particularly useful to design the tire so that negative camber of about 20° in the wheels on the outside of the curve is feasible. According to this embodiment, the convex tread section facing the longitudinal middle of the vehicle is dimensioned so that in cross section the convex tread has a center plane or plane of symmetry which extends upwards and outwards at about 20° to a radial plane and intersects the radial plane located at the transition from the flat tread section to the convex section at the center of curvature, in particular of the circle of curvature of the convex tread section.
According to the present invention, it is useful if the flat tread section that faces the outside of the vehicle and wheel constitutes at least 50%, but preferably about ⅗ to ⅘, of the width of the tread, so that the width of the convex tread section constitutes ⅕ to ⅖ of the total width of the tread. Even if a variety of different widths are optimal for the uses described above, a good rule-of-thumb is to use a width ratio such that the flat tread section constitutes ⅔ and the convex tread section ⅓ of the total width of the tread.
A circular arc shape is useful for the convex tread section, and the flat tread section should transition into the convex tread section that faces the middle of the vehicle. The radius of curvature of the convex tread section is preferably greater than its width, so that the convex tread section forms a relatively flat curve and can be roughly in the shape of a parabola. The radius of curvature of the convex tread section is preferably 1.25 to 1.75 times greater than the width of that part of the tread.
The radius of curvature of the convex tread secti
Mäckle Günther
Schirle Thomas
Kenyon & Kenyon
Maki Steven D.
LandOfFree
Pneumatic tire for wheels of multiple-track vehicles does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Pneumatic tire for wheels of multiple-track vehicles, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pneumatic tire for wheels of multiple-track vehicles will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2898754