Resilient tires and wheels – Tires – resilient – Pneumatic tire or inner tube
Reexamination Certificate
2001-05-14
2004-05-18
Ball, Michael W. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Pneumatic tire or inner tube
C152S520000, C152S157000, C152S310000
Reexamination Certificate
active
06736176
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a tire capable of usually running even after being subjected to an external injury, and more particularly to a safety tire having excellent durability and ride comfort in the running after the tire is subjected to an external injury.
2. Description of Related Art
In a pneumatic tire, e.g. a pneumatic tire for a passenger car, air is sealed in an inside of the tire under an internal pressure of about 250-350 kPa (absolute pressure, and so forth) to generate tension in a skeleton portion of the tire such as carcass, belt and the like, and by this tension it is possible to conduct deformation and restoration of the tire due to input to it. That is, constant tension is generated in the skeleton of the tire by holding its internal pressure of the tire within a given range to provide a load bearing function and to enhance the rigidity for providing basic performances required in the running of a vehicle such as traction, braking, cornering performances and the like.
When the tire held at the given internal pressure is subjected to an external injury, air leaks out through the external injury toward an exterior to reduce the internal pressure up to an atmospheric pressure or render into so-called puncture state, so that tension generated in the skeleton portion of the tire is substantially lost. As a result, the load bearing function as well as the traction, braking and cornering performances obtained by applying the given internal pressure to the tire are also lost and hence it is impossible to run the vehicle provided with such a tire.
For this end, there are many proposals with respect to safety tires capable of running even at the puncture state. As a pneumatic safety tire for automobiles, there are proposed, for example, tires of various types such as a tire having a double wall structure, a tire including a load bearing device therein, a tire strengthening a sidewall portion and so on. As a practically used technique among these proposals, there is a tire wherein a sidewall reinforcing layer made of a relatively hard rubber is arranged in an inner face of the tire about a sidewall portion of the tire from a shoulder portion to a bead portion. This type of tire is used as so-called run-flat tire mainly having an aspect ratio of not more than 60%.
However, the method of adding the sidewall reinforcing layer increases a tire weight by 30-40% and raises a longitudinal spring constant of the tire, so that there is a disadvantage of bringing about a serious degradation of rolling resistance and a lowering of ride comfort in the usual running before puncture. Therefore, this method badly affects the performances in the usual running, fuel consumption and environment, and is a technique being still poor in the general-purpose property.
On the other hand, as a pneumatic tire having a high tire section height and an aspect ratio of not less than 60%, there is mainly adapted a run-flat tire having such a structure that an internal support body such as a core or the like is fixed to a rim to support a load in the puncture for avoiding heat build-up of the sidewall portion during the running at a relatively high speed over a long distance.
In this case, however, the tire can not withstand to local repetitive stresses produced between the tire and the internal support body at a run flat state after the puncture, and hence the running distance after the puncture is limited to about 100-200 km. In addition, there is a problem that an operation of arranging the internal support body inside the tire and assembling the tire onto a rim is complicated and requires a long time. In this connection, there is proposed means for forming a difference in a rim diameter between one end side and the other end side in a widthwise direction of the rim to facilitate the insertion of the internal support body, but a satisfactory effect is not yet obtained.
Moreover, in order to prolong the running distance after the puncture of the run-flat tire having the internal support body therein, it is effective to add a skeletal member to render the tire structure into a more massive state, but the rolling resistance and ride comfort in the usual running are degraded by the addition of the skeletal member, so that there is no reality in the adoption of this means.
Furthermore, a tire wherein a composite body having closed cells is filled in an inner space of an assembly of a tire and a rim is disclosed, for example, in JP-A-6-127207, JP-A-6-183226, JP-A-7-186610 and JP-A-8-332805. The tires proposed in these documents are mainly limited to a special or small-size tire such as agricultural tire, rally tire, motorcycle tire, bicycle tire or the like. Therefore, there is not known the application to tires regarding the rolling resistance and ride comfort as important such as tires for passenger car, tires for truck and bus and so on. And also, the composite body is low in the expansion rate, so that the weight of the composite body having the closed cells is large and it is unavoidable to degrade the ride comfort against vibration and fuel consumption. Furthermore, the inside of the closed cell is atmospheric pressure, so that the use of the composite body instead of a high pressure air in the conventional pneumatic tire is functionally insufficient.
In Japanese Patent No. 2987076 is disclosed a puncture-free tire inserting a foamed filling member into an inner peripheral portion of the tire. In addition to the disadvantage due to the fact that the internal pressure is very close to an atmospheric pressure, however, since the foamed body is urethane-base, energy loss resulted from intermolecular hydrogen bond of urethane group is large and self-heating is high. Therefore, when such a foamed body made of urethane is filled in the tire, heat generation is caused in the foamed body by repetitive deformation during the running of the tire to largely lower the durability. And also, since something that is hard to form closed cells is used as a starting material, the resulting cells are easily connected to each other and it is difficult to hold a gas in the foamed body, and hence there is a disadvantage that a desired internal pressure of the tire (load bearing ability or a deflection controlling ability) is not obtained.
Moreover, JP-A-48-47002 proposes a puncture-free tire wherein a plurality of expanded pressure cellular bodies each formed by integrally covering and sealing an outer periphery of a multi-cell body mainly composed of closed cells with an outer coating of rubber, synthetic resin or the like having a thickness of 0.5-3 mm are filled in an inside of a tire so as to hold a given internal pressure. According to this technique, in order to make a pressure in the cell of the cellular body higher than an atmospheric pressure, an amount of a foaming agent compounded in a starting material for the formation of closed cells constituting the expanded pressure cellular body is set to an amount generating gas in an amount at least equal to or more than an internal volume of the tire, whereby it is aimed at the development of performances at least equal to those of the usual pneumatic tire.
In the above technique, in order to prevent the scattering of gas in the cell of the expanded pressure cellular body, the body is integrally covered and sealed with the outer coating, but only materials such as tube for automobile or a blend for the formation of the tube are exemplified as a material for the outer coating. In other words, the multi-cell body is covered and sealed with a soft elastic outer coating mainly composed of butyl rubber having a low nitrogen gas permeability, which is used in a tire tube or the like, and a plurality of such covered multi-cell bodies are filled in the tire. As the production method, an uncured tire tube as the soft elastic outer coating and a starting material for the formation of an uncured cellular body as an expanded pressure cellular body are used and disposed in an inside of a tire-rim assembly and expanded by heat
Ball Michael W.
Bridgestone Corporation
Fischer Justin
LandOfFree
Tires does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Tires, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tires will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3267838