Methods and Apparatus for Modifying Ice Adhesion Strength for Skis

Ice adhesion causes many problems. For example, ice on aircraft wings endangers the plane and its passengers. Ice on ship hulls creates navigational difficulties and the expenditure of additional power to navigate through water and ice. Icing of power lines often results in their break and loss of power. The need to scrape ice that forms on automobile windshields is regarded by most adults as a bothersome and recurring chore, and any residual ice risks driver visibility and safety.

The above-referenced problems generally derive from the propensity of ice to stick and form onto surfaces. However, ice also creates great difficulties in that it has an extremely low coefficient of friction, as well. Each year, for example, ice on the roadway causes millions of automobile accidents, costing both human life and extensive property damage. If automobile tires gripped ice more efficiently, there would likely be fewer accidents.

Known methods for dealing with ice adhesion vary, though most techniques involve some form of scraping, melting or breaking. For example, the aircraft industry utilizes a de-icing solution such as Ethyl Glycol to douse aircraft wings to melt the ice thereon. This process is both costly and environmentally hazardous however, the risk to passenger safety warrants its use. Other aircraft utilize a rubber tube aligned along the front of the aircraft wing, whereby the tube is periodically inflated to break any ice disposed thereon. Still other aircraft redirect jet engine heat onto the wing so as to melt the ice. All these methods have serious limitations and difficulties.

Dartmouth’s scientists have invented a system and various methods to modify ice adhesion and ice friction to alleviate these problems. Dartmouth’s system will reduce ice adhesion on vehicle surfaces such as aircraft wings, ship hulls, power lines, and windshields. It also increases the coefficient of friction between ice-clad roads and automobile tires, and between ice and other objects such as shoe soles and cross-country skis. The system is cheap, simple and durable.

The device developed at Dartmouth applies an electric field to the interface between ice and surfaces in contact with the ice. By appropriate control of the field strength, the ice becomes essentially *stick-free* to such a degree that ice can be removed from the surfaces with very little effort. The device thus has particular importance in aircraft safety since ice which forms on aircraft wings can be removed during flight and by normal aerodynamic forces, as opposed to complex and environmentally hazardous de-icing techniques which can only occur on the ground. Ice from car windows is similarly removed with less force and scraping.

The device includes a power supply, e.g., a battery, and a plurality of electrodes. One electrode connects electrically with the surface of interest - e.g., the aircraft wing - while at least one other electrode is suspended in close proximity to the surface. As ice bridges the gap between the electrodes, the field is generated at the ice-surface interface. The suspended electrode might include a multitude of electrodes which form-fit to the surface of interest, so as to remove unconnected patches of ice.

In certain configurations, the device also includes control electronics to measure and modulate the applied electric field to minimize the adhesion strength for a given set of circumstances.

Finally, the device can also operate to increase the ice adhesion strength thereby increasing the interactive forces between the ice and surfaces in contact with the ice. Ice-gripping shoes would increase the coefficient of friction between the shoe sole and any icy surface, so walking on ice would feel like dry pavement. The technology works by applying an electric field to the ice-shoe interface, causing ice crystals to rapidly grow between the ice and shoe sole, which both increases contact area and requires breaking of the new crystals in order to slip or slide. The ice-gripping systems, including control electronics, may be powered by one AAA battery and can activate adhesion automatically when ice is detected, or by pressure from walking. The system requires a fine network of electrodes on the shoe soles, which can be manufactured from conductive rubber.

Applying the ice-gripping systems to ski bases will use the same technology, but can be simplified by the use of a network of metal electrodes that is separated from the ice by a thin insulating layer, such as normal ski base material. This technology can increase uphill and backward traction for cross-country skiing, or be used as a braking mechanism for downhill skiing. For downhill skiing, it would be possible to program a maximum speed and then have the ice adhesion system activate automatically when the pre-programmed speed limit is exceeded; continuous moderate adhesion for speed control is also possible. This could be a valuable safety feature for inexperienced skiers, or for any skier who fears losing control. The technology is not limited to skis, however, as all potential sports equipment applications, such as brakes for ice skates, and de-icing of ski lift equipment could benefit from it.

It should be noted that in order for the device to operate properly, the surface of interest must be conductive. Therefore, in the applications above, the windshield glass and automobile tires must be doped with conductive material to adequately conduct electricity. Special coating applied to the power line during manufacture or as a subsequent treatment would generate an exact amount of heat suitable to melt ice and snow and only when the temperature dips below freezing. This method provides 100% protection. However, most surfaces, such as aircraft wings, are already conductive and so the conductivity is not an issue.

This technology is claimed in the issued United States patent No. 6,027,075 entitled METHODS AND APPARATUS FOR MODIFYING ICE ADHESION STRENGTH, and United States patent No. 6,427,946 entitled SYSTEMS AND METHODS FOR MODIFYING ICE ADHESION STRENGTH. Eighteen patent applications claiming various enhancements to the technology are pending. We are seeking industrial partners interested in further developments of this technology in various fields. (Ref: J49

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