JP2004501015A - System and method for electrical deicing coating - Google Patents

Abstract

A system for changing the adhesion of ice attached to an object comprising a composite coating comprising a wire electrode covering the surface to be protected. In one embodiment, the composite coating includes electrode wires and insulator fibers. The composite coating is applied to the surface of the object whose ice adhesion is to be changed. The electrode wires are connected to a dc bias source, and these wires alternately perform cathode and anode functions. As the ice completes the circuit between the anode and cathode wires, the source creates a DC bias at the interface between the ice and the surface. In another embodiment, a wire mesh is placed on the conductive surface of the object and a reverse DC bias is applied to the mesh and the surface. In another embodiment, the coating has anode and cathode wires woven by insulator fibers as a composite cloth applied to the surface to protect the surface from ice.
[Selection diagram] FIG.

Description

[0001]
(1. Field of the Invention)
The present invention relates to methods, systems and structures for changing the adhesion of ice between ice and a selected object. More specifically, the present invention relates to methods, systems and structures for applying electrical energy to the interface between ice and an object to increase or decrease the adhesion of ice to promote a desired result.
[0002]
(2. Explanation of the problem)
The adhesion of ice to a particular surface causes many problems. For example, excessive accumulation of ice on the wings of an aircraft puts the aircraft and its passengers at risk. Ice in the hull creates navigation problems, additional waste of power to navigate through the water and ice, and certain unsafe conditions. The need to scrape off the ice formed on the windshield of an automobile is a tedious and repetitive chore for most adults, and the remaining ice compromises the visibility and safety of the driver.
[0003]
Icing and ice build-up also cause problems for helicopter blades and public roads. Billions of dollars are spent removing and controlling ice and snow. Ice adheres to metals, plastics, glass and ceramics, causing other problems in everyday life. Icing on transmission lines is also problematic. Icing adds weight to power lines, causing power outages and direct and indirect costs of billions of dollars.
[0004]
In the prior art, there are various methods of handling the adhesion of ice, but most techniques involve scraping, melting or breaking. For example, the aviation industry utilizes deicing solutions, such as ethyl glycol, which are poured onto the wings of an aircraft to melt the ice thereon. This process is costly and harmful to the environment. However, the presence of dangers to passenger safety ensures that it is used. Other aircraft utilize rubber tubing aligned along the front of the aircraft wing. This causes the tube to expand periodically, destroying any ice attached to the wing. Still other aircraft transfer the heat of the jet engine onto the wings to melt the ice.
[0005]
These conventional methods have limitations and problems. First, prop-propeller aircraft do not have jet engines. Second, placing rubber tubes in front of the aircraft wing is not aerodynamically efficient. Third, deicing costs are extremely high, $ 2,500-3500 per application, and can be applied up to about 10 times per day on certain aircraft. For other types of objects, it is common to heat ice and snow. However, heating certain objects is technically impractical. Furthermore, the large consumption of energy and complicated heating equipment often makes the heating process expensive.
[0006]
The above-mentioned problems are usually due to the property of ice that forms on and adheres to the surface. However, ice poses a problem in that it has a very low coefficient of friction. For example, each year ice on the road causes many car accidents, at the cost of human life and high property damage. If the car tires have more efficient grip, the number of accidents will probably decrease.
[0007]
US Pat. No. 6,027,075, incorporated herein by reference, discloses certain embodiments of the invention. Therein, electrical energy in the form of a direct current ("DC") bias is applied to the interface between the ice and the object covered by it. As a result, the adhesion of ice to the surface of the object changes. Usually, the adhesion of the ice is reduced, making it possible to remove the ice from the object by wind pressure, buffeting or light brushing manually. In other applications, the adhesion of the ice between the ice and the surface of the object in contact with the ice is increased. For example, as the adhesion of ice increases between the automobile tire and the icy road, slippage is reduced and accidents are reduced. In general, if charge is generated at the interface of the ice in contact with the object, it is possible to selectively vary the adhesion between the ice and the object.
[0008]
In general, U.S. Patent No. 6,027,075 discloses a power supply connected to apply a DC voltage across the interface between ice and an object surface having ice thereon. By way of example, an object having a conductive surface can be an aircraft wing or hull (or even paint applied to a structure). U.S. Patent No. 6,027,075 discloses a first electrode connected to a surface. This is because a non-conductive or electrically insulating material is applied over the surface as a grid, for example, by applying a conductive material such as a conductive paint over the insulating material, but without contacting the surface. Is formed. However, a practical problem with the grid electrode system disclosed in US Pat. No. 6,027,075 is the formation of the grid electrode and its associated insulating layer. The individual components of the grid system, including the electrodes, wiring and insulators, are manufactured on a small scale. Photolithographic techniques are capable of producing such grating systems. Photolithography is used very effectively in the fabrication of integrated circuits. Using photolithography to form a grid system to alter ice adhesion is not very suitable. This involves many patterning and etching steps. When applied to ice control techniques, photolithography is expensive, complex and uncertain.
[0009]
(solution)
The present invention replaces the grating disclosed in US Pat. No. 6,027,075. One embodiment of the present invention provides a composite coating that includes closely spaced discrete wire electrodes separated by insulator fibers. The wire electrodes and insulator fibers are usually knitted using known reliable industrial techniques. The wire electrodes are alternately connected to a DC power supply to function as a cathode and an anode. The composite coating is durable and flexible and is usually applied to the surface to be protected using conventional adhesives. The metal wire can be gold, platinum plated titanium or niobium, or other materials that have a high resistance to electrolytic corrosion. Nylon, glass or other dielectric materials may be used as the dielectric insulator fibers. The dielectric fibers keep the metal electrodes apart while providing the integrity of the coating. In addition, the dielectric insulator fibers electrically insulate the wire electrode from the composite coated surface. Typical wire diameters are in the range of 10-100 μm, the same range as the open space between the electrode wires and the insulating fibers. When ice forms in or on the composite coating, a dc bias is applied to the electrodes. As a result, the adhesion of the ice at the interface between the ice and the surface of the object to be protected changes.
[0010]
In another embodiment of the invention, the wire electrodes of the composite coating are connected to a DC bias source so that they have the same DC bias. The surface provided with the composite coating is conductive and has a reverse DC bias. Ice formed in the space of the composite coating closes the electrical circuit.
[0011]
In another embodiment of the present invention, a wire mesh including a conductive wire is formed. The wire mesh is disposed on the conductive surface and an insulating layer is inserted between the wire mesh and the surface. A DC bias is applied to the wire mesh and a reverse DC bias is applied to the surface. Ice formed in the space of the wire mesh closes the electrical circuit.
[0012]
Those skilled in the art will appreciate that the above-described system can be applied to the surface of many objects where it is desired to reduce ice adhesion, such as automotive windshields, airplane wings, hulls and power lines. When the present invention is in the form of a composite cloth, it includes both the functional anode and the functional cathode necessary for the system to function. Thus, it does not matter whether the surface of the object to be protected is conductive or non-conductive.
[0013]
Next, the present invention will be further described in connection with a preferred embodiment. It will be apparent that various additions, deletions and modifications can be made by those skilled in the art without departing from the scope of the invention.
[0014]
The invention can be more completely understood with reference to the figures.
[0015]
(Detailed description of preferred embodiments)
The present invention includes methods, systems and structures for changing the adhesion of ice to objects such as metals and semiconductors by applying a DC bias to the interface between ice and the object. FIG. 1 shows one system 10 that incorporates an electro-deicing coating 12 that affects ice 14 that may adhere to a surface 16. Surface 16 may be associated with, for example, airplane wings, helicopter blades, jet intakes, heat exchangers for kitchens and industrial equipment, refrigerators, road signs, ship overstructures, or cold, moisture and ice. It can be another object that is exposed to the conditions. More specifically, coating 12 is applied over surface 16 and protects surface 16 from ice 14. The coating 12 is preferably flexible so that it physically matches the shape of the surface 10. In operation, a voltage is applied to coating 12 by power supply 18. Typically, this voltage is 2 volts or more, and is typically between 100 and 200 volts. For lower temperatures, higher voltages are applied. As an example, if the temperature in the coating 12 (discussed in more detail below) is −10 ° C. and the spacing between the anode and cathode is 50 μm, about 20 V will be applied to the coating 12, and a very high voltage, such as that found on an aircraft wing, will be observed. A current density of 10 mA / cm ² is provided through pure atmospheric ice.
[0016]
When a voltage is applied, the ice 14 is broken down into gaseous oxygen and hydrogen by electrolysis. In addition, gas is formed in the ice 14 and creates high-pressure bubbles that detach the ice 14 from the coating 12 (and thus from the surface 16). Typical current densities applied to the coating 12 are about 1-10 mA / cm ² . If desired, the voltage regulation subsystem 20 is connected by feedback to the power supply 18 and thus to the circuit formed by the coating 12 and the ice 14 to optimally increase or decrease the DC voltage applied to the coating 12. I do.
[0017]
FIG. 2 illustrates one system 40 that incorporates an electro-deicing coating 12 that affects ice 44 that may adhere to a conductive surface 46. The conductive surface 46 may be used, for example, in aircraft wings, helicopter blades, jet inlets, heat exchangers in kitchens and industrial equipment, refrigerators, signs, ship superstructures, or in conditions involving cold, moisture and ice. It can be another object that is being exposed. More specifically, coating 42 is applied over surface 46 to protect surface 46 from ice 44. The coating 42 is preferably flexible so that it conforms physically to the shape of the surface 46. In operation, a voltage is applied between coating 42 and surface 46 by power supply 48. The bias voltage applied to coating 42 may be equal to and opposite to the bias voltage applied to surface 46. If desired, an insulator 45 may be disposed between the coating 42 and the surface 46, and the insulator 45 preferably includes a dielectric mesh configuration as described below.
[0018]
Typically, the voltage between the coating 42 and the surface 46 is greater than or equal to 2 volts, and is typically between 2 and 100 volts. For lower temperatures, higher voltages are applied.
[0019]
When a voltage is applied, the ice 44 is broken down into gaseous oxygen and hydrogen by electrolysis. In addition, gas is formed in the ice 44 and creates high pressure bubbles that detach the ice 44 from the coating 42 (and thus from the surface 46). Typical current density applied to coating 42 is about 1~10mA / cm ^2. If desired, the voltage regulation subsystem 50 is connected to the power supply 48 by feedback, and thus to the circuit formed by the coating 42, the surface 46 and the ice 44, to optimally control the DC voltage applied to the coating 42. Increase or decrease.
[0020]
Thus, the systems 10, 40 alter the electrostatic interaction that forms the bond between ice and metal. These interactions are effectively changed (reduced or enhanced) by applying a small DC (direct current) bias between ice and metal. As described below, the composite coating is applied to a surface 16 that includes metal electrode wires separated by dielectric insulator fibers and requires protection against ice. Applying a dc bias changes the adhesion of ice between ice and the electrodes of the coating and between ice and the surface.
[0021]
Ice has certain physical properties that allow the present invention to selectively alter the adhesion of ice to conductive (and semiconductive) surfaces. If a charge is generated on a surface that comes into contact with ice, it is possible to selectively change the adhesion of the two surfaces. First, ice is a proton semiconductor, a small class of semiconductors, whose charge carriers are protons rather than electrons. This phenomenon results from hydrogen bonding inside the ice. Like normal semiconductors based on electrons, ice is conductive, but this conductivity is generally weak.
[0022]
Another physical property of ice is that its surface is covered with a liquid-like layer (LLL). LLL is an important physical property. First, LLL is only nanometers thick. Second, its viscosity ranges from near watery at or below freezing to very viscous at low temperatures. In addition, LLL is present at temperatures as low as -100C.
[0023]
LLL is also a major factor in ice adhesion. The combination of the semi-conductive properties of ice and LLL allows for selective manipulation of the ice adhesion between the ice and other objects. Usually, the water molecules inside the ice pieces are randomly oriented. However, on the surface, the molecules are oriented outward or inward in substantially the same direction. As a result, all the protons, and thus the positive charges, of these molecules are directed outward or inward. Although the exact mechanism is not known, the transfer of water molecules to an ordered orientation within the LLL can be considered irregular. However, the practical consequence of ordering is that a high density of positive or negative charges is created at the surface. Thus, if a charge is generated on a surface that comes into contact with ice, it is possible to selectively change the adhesion between the two surfaces. External electrical bias applied at the ice / other surface interface reduces or enhances ice adhesion to other objects, as similar charges are repelled and attract opposite charges.
[0024]
Ice contains polar water molecules that interact violently with any solid substrate that has a different dielectric constant than ice. In addition, there is theoretical and experimental evidence that a surface charge exists in ice. This surface charge can also interact with the substrate.
[0025]
Electrolysis is an important factor. As dc current flows through the ice, gaseous hydrogen (H ₂ ) and oxygen (O ₂ ) accumulate in the form of small bubbles at the ice interface due to ice electrolysis. These bubbles affect the generation of interface cracks and reduce the adhesion of ice.
[0026]
FIG. 3 shows a composite coating 100 having a cathode wire 102 and an anode wire 104 according to the present invention. The dielectric wire 106 forms an insulating weave around the wires 102, 104 to avoid short circuits. Wires 102, 104 are connected to power supply 18 (or power supply 48), for example, such that the appropriate current density affects ice adhering to coating 100. Typically, the power density is reduced to reduce adhesion between ice and coating 100 such that coating 100 serves to protect surfaces such as surface 16 from ice. A typical space between the wires 102 is 10 to 50 μm, and a typical space between the wires 104 is also 10 to 50 μm. The wires 102, 104 may include, for example, gold, platinum plated titanium or niobium, or other metals that have a strong resistance to electrolytic corrosion.
[0027]
FIG. 4 shows a composite coating 120 according to the present invention. The coating 120 has alternating electrode wires 122, each wire having an equal bias from the connected power supply. The coating 120 can be applied, for example, to the surface 46 of FIG. In this case, the surface 46 is conductive. A voltage potential exists between surface 46 and wire 122. Insulating mesh 124 prevents shorting of wire 122 and further prevents shorting between wire 122 and surface 46. The ice 44 completes the circuit between the wire 122 and the surface 46 and causes the change in ice adhesion of the present invention.
[0028]
FIG. 5 shows a wire mesh coating 150 constructed in accordance with the present invention. The mesh coating 150 is typically conductive, and the wires 152 and the weave components 154 are conductive. Accordingly, a mesh coating 150 is applied to the conductive surface 46 with the insulator 45 disposed therebetween. Insulator 45 is configured to protect surface 46 when ice 44 completes the circuit between mesh coating 150 and surface 46. The voltage potential between the mesh coating 150 and the surface 46 changes the adhesion of the ice 44 as desired.
[0029]
Normal current density applied to coatings of the present invention is 1~10mA / cm ^2. Operating voltages typically range from 2 to about 100 volts, depending on ice temperature and spacing between wires. The lower the temperature, the higher the required voltage. The greater the spacing between the wires, the higher the required voltage. For a typical temperature of −10 ° C. and 50 μm spacing, a bias of about 20 volts provides a current density of about 10 mA / cm ² through very pure ice.
[0030]
It is important that the anode wire 104 (FIG. 3) has very strong resistance to anodic corrosion. To that end, the wire may be coated with a thin layer of platinum or gold or amorphous carbon. Other alloys may be provided. The cathode wire 102 also does not pass hydrogen. Examples of good cathode materials include gold, copper, brass, bronze and silver.
[0031]
The composite coating or wire mesh according to the invention is flexible. It protects a wide variety of surface materials and shapes, including, for example, airplane wings, helicopter blades, protection grills at jet engine inlets, heat exchangers for kitchens and industrial refrigerators, signs and ship superstructures. obtain.
[0032]
The wire mesh and composite coating described herein can be made using conventional methods used in the industry. The mesh or composite coating of the present invention can be applied to a surface simply by stretching it over the surface, and a thin layer of adhesive is disposed between the composite coating or mesh and the surface.
[Brief description of the drawings]
FIG.
FIG. 1 shows a deicing system including an electrical coating for deicing surfaces according to the present invention.
FIG. 2
FIG. 2 illustrates an alternative deicing system that includes an electrical coating for deicing surfaces according to the present invention.
FIG. 3
FIG. 3 shows a composite coating having a cathode wire and an anode wire according to the invention, which acts to change the adhesion of ice formed on the surface.
FIG. 4
FIG. 4 shows a composite coating according to the invention, wherein the electrode wires have the same bias.
FIG. 5
FIG. 5 shows a wire mesh according to the invention.

Claims (27)

A system for changing the adhesion of ice adhered to a conductive surface,
A wire mesh covering the surface, a composite coating having the coating comprising conductive wires;
A non-conductive insulating layer between the coating and the surface;
A DC power supply for applying a DC bias between the mesh and the surface via a circuit formed by ice. The system of claim 1, further comprising an adhesive for applying the composite coating to the surface. The system of claim 1, wherein the surface and the wire mesh are connected to opposite ends of the DC power supply. The system of claim 1, wherein the DC bias provides a current density of about 1-10 mA / cm ² with ice. The system of claim 1, wherein the DC bias provides a voltage potential between about 2 and 100 between the surface and the mesh. A system for changing the adhesion of ice adhered to a conductive surface,
A composite coating covering the surface, the composite coating comprising a plurality of conductive electrode wires and a plurality of electrically insulating insulator fibers, the insulator fibers separating each of the electrode wires from each other, A composite coating that insulates from the surface;
A system comprising: a DC power supply for applying a DC bias between the electrode wires and the surface via the circuit formed by the ice. The system of claim 6, further comprising an adhesive for applying the composite coating to the surface. 7. The system of claim 6, wherein the surface is connected to one end of the DC power supply and the electrode wire is connected to an opposite end of the DC power supply. The system of claim 6, wherein the electrode wires include a cathode wire and an anode wire. The system of claim 6, wherein the composite coating is a composite cloth. The system of claim 10, wherein the composite cloth is braided with electrode wires and insulator fibers. 12. The system of claim 11, wherein the electrode wires are braided in a generally vertical direction with respect to the insulator fibers. The system of claim 6, wherein the electrode wire comprises one of gold, copper, brass, bronze, silver, and mixtures thereof. 14. The system of claim 13, further comprising a coating over the wire, wherein the coating is selected from the group of platinum, gold, and amorphous carbon. 7. The method of claim 6, wherein the electrode wire comprises an anode wire and a cathode wire, and the power supply alternately generates a bias between the surface and the anode wire and between the surface and the cathode wire. The described system. A system for changing the adhesion of ice adhered to a surface,
A composite coating covering the surface, the composite coating comprising a plurality of cathode wires, a plurality of anode wires, and electrically insulating insulator fibers;
A system comprising: a DC power supply for applying a DC bias between the cathode wire and the anode wire via a circuit formed by the ice. 17. The system of claim 16, wherein said cathode wire is connected to one end of said DC power supply and said anode wire is connected to the other end of said DC power supply. 17. The system of claim 16, wherein the DC power source is a battery. 17. The system of claim 16, wherein the surface comprises a surface of an aircraft wing. 17. The system of claim 16, wherein the surface comprises a power line surface. 17. The system of claim 16, further comprising an adhesive for applying the composite coating to the surface. 17. The system of claim 16, wherein the composite coating is a composite cloth. 23. The system of claim 22, wherein the composite cloth is woven with the cathode wire, the anode wire, and the insulator fiber. 24. The system of claim 23, wherein the cathode wire and the anode wire are braided in a generally vertical direction with respect to the insulator fiber. 17. The system of claim 16, wherein the cathode wire comprises one of gold, copper, brass, bronze, silver, and mixtures thereof. 17. The system of claim 16, wherein the anode wire comprises one of gold, copper, brass, bronze, silver, and mixtures thereof. 27. The system of claim 26, further comprising a coating over the anode wire, wherein the coating is selected from the group of platinum, gold, and amorphous carbon.
(Background of the Invention)

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