Resilient tires and wheels – Tires – resilient – Anti-skid devices
Reexamination Certificate
1998-06-01
2001-03-13
Maki, Steven D. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Anti-skid devices
C152S210000, C152S211000
Reexamination Certificate
active
06199610
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an antiskid device suitable for driving an automobile or walking on foot on a frozen or snowy surface. The present invention also relates to an antiskid tire.
BACKGROUND ART
As a common antiskid means for an automobile tire used on a frozen road, metal spikes used to be popularly mounted to the tire. According to this means however, when the automobile is running, the spikes grind the road surface so excessively that the road is severely damaged. In addition, a large amount of dust results. To overcome these problems there is proposed a means such as one disclosed in Japanese Patent Publication No. 1-249003.
According to the means disclosed in the above patent publication, pins made of a predetermined rubber component are mounted to the tire instead of the metal spikes. The pins harden at and below the freezing temperature whereas they soften at higher temperatures. Such a means makes possible to use the hardened pins as spikes at temperatures below the freezing point when the road is frozen. On the other hand, at normal temperatures when the road is not frozen, the pins are softened so that it becomes possible to prevent the pins from unduly grinding the road surface.
However, the above prior art has the following disadvantages.
First, when the car is running, the tires of the car generate eat due to intermolecular friction of the tire rubber and friction from the road, and the heat transfers to each of the pins. Specifically, when the car is running at 40 km/h, the rubber of the tire has an internal temperature of 60° C. to 70° C., increasing the temperature of the pins. Thus, according to the above prior art, even if the car is running on a frozen road, there is an occasion when the heat from the tire prohibits the pins from hardening to a sufficient level necessary for functioning as the spikes.
This problem may be solved by making the pins harden at a higher temperature. However, such can only be achieved by mixing the material rubber with a large amount of additives, which decreases elasticity and strength of the pin, leading to another problem that the pins would be easily damaged when contacted by the road.
Second, when the car is running, the tip potion of the pin contacts the frozen road of a low temperature whereas the base portion of the pin receives heat from the tire. As a result, there is a large temperature difference between the tip portion and the base portion of the pin, causing a substantial difference in the hardness between the tip portion and the base portion of the pin. The base portion which is softer becomes more susceptible to deformation. This leads to a problem that stresses from the operating tire concentrate on the base portion of the pin, causing the pin to fail from fatigue.
DISCLOSURE OF THE INVENTION
It is therefore an object of the present invention to provide an antiskid device capable of eliminating or alleviating the above problems.
Another object of the present invention is to provide an antiskid tire using such antiskid devices.
According to a first aspect of the present invention, an antiskid device is provided. The antiskid device comprises a pin having a higher hardness in a first temperature range not higher than a predetermined temperature and a lower hardness in a second temperature range above the predetermined temperature, and a heat insulating member provided at one end of the pin.
According to a preferred embodiment of the present invention, the pin is formed integrally with the heat insulating member by simultaneous molding.
According to another preferred embodiment of the present invention, the pin is formed of a polymer which is prepared by plasticizing polynorbornene with an aromatic oil. The heat insulating member is formed of a polymer which is prepared by plasticizing polynorbornene with an aromatic oil, and this polymer is mixed with a heat insulating material.
According to a second aspect of the present invention, an antiskid tire is provided. The antiskid tire has a tread provided with antiskid devices. Each of the antiskid devices comprises a pin having a higher hardness in a first temperature range not higher than a predetermined temperature and a lower hardness in a second temperature range above the predetermined temperature, and a heat insulating member at a base end of the pin.
According to a preferred embodiment of the present invention, the tread of the tire includes a recess for receiving each of the antiskid devices. The pin has a tip which is generally flush with or slightly retracted from a surface of the tread.
According to another preferred embodiment of the present invention, the pin has a higher hardness than the tread in the first temperature range and a lower hardness than the tread in the second temperature range.
According to a third aspect of the present invention, an antiskid tire is provided. The antiskid tire has a tread provided with first antiskid devices and second antiskid devices. Each of the first antiskid devices comprises a pin having a higher hardness than the tread in a first temperature range not higher than a predetermined temperature and a lower hardness than the tread in a second temperature range above the predetermined temperature, and a heat insulating member at a base end of the pin. Each of the second antiskid devices comprises a pin made of a rubber having a higher hardness than the tread in a wide temperature range from low to high temperatures.
According to a preferred embodiment of the present invention, each of the second antiskid devices includes a heat insulating member for insulating heat transfer from the tire to the pin of the second antiskid device.
Other features and advantages of the present invention will become clear from the embodiments described below with reference to the accompanying drawings.
REFERENCES:
patent: 3566948 (1971-03-01), Menell
patent: 3831655 (1974-08-01), Cantz
patent: 5324369 (1994-06-01), Yamada
patent: 5681649 (1997-10-01), Mashita et al.
patent: 5800644 (1998-09-01), Eromaki
patent: 23715 (1906-01-01), None
patent: 368411 (1932-03-01), None
patent: 57-172803 (1982-10-01), None
patent: 1-249003 (1989-10-01), None
patent: 2-84459 (1990-03-01), None
patent: 3-54006 (1991-03-01), None
patent: 4-358908 (1992-12-01), None
patent: 7-256825 (1995-10-01), None
patent: 7-315012 (1995-12-01), None
patent: 8-118920 (1996-05-01), None
Goichi Rubber Co., Ltd.
Maki Steven D.
Merchant & Gould P.C.
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