Heat Units Using a Solid Fuel Capable of Undergoing an Exothermic Metal Oxidation-Reduction Reaction Propagated without an Igniter

Abstract

A heating unit comprising an electrically conductive substrate. A solid fuel layer comprising a metal reducing agent, a metal containing oxidizing agent and a binder is coated on a surface of the substrate, the solid fuel layer having a solid fuel surface spaced from the substrate. A first electrode coupled to the substrate. A second electrode coupled to the solid fuel surface. A power supply is configured to be selectively coupled to the first and second electrodes to provide a voltage between the metallic substrate and the solid fuel surface. The voltage acts to propagate an exothermic metal oxidation-reduction reaction without the use of an igniter.

What is claimed is: 
     
         1 . A heating unit comprising:
 an electrically conductive substrate;   a solid fuel layer comprising a metal reducing agent, a metal containing oxidizing agent and a binder coated on a surface of the substrate, the solid fuel layer having a solid fuel surface spaced from the substrate;   a first electrode coupled to the substrate;   a second electrode coupled to the solid fuel surface; and   a power supply configured to be selectively coupled to the first and second electrodes to provide a voltage between the electrically conductive substrate and the solid fuel surface.   
     
     
         2 . The heating unit of  claim 1  wherein the electrically conductive substrate comprises a metal. 
     
     
         3 . The heating unit of  claim 1  wherein the electrically conductive substrate comprises a steel foil. 
     
     
         4 . The heating unit of  claim 1  wherein the metal reducing agent is selected from at least one of the following: zirconium, titanium, aluminum and iron. 
     
     
         5 . The heating unit of  claim 1  wherein the metal containing oxidizing agent is selected from at least one of MoO 3 , MnO 2 , Fe 2 O 3 , KClO 4  and KClO 3 . 
     
     
         6 . The heating unit of  claim 1  wherein the binder is selected from at least one of the following: nitrocellulose, polyvinyl alcohol, diatomaceous earth, glass beads, colloidal silica, and a clay gelling agent. 
     
     
         7 . The heating unit of  claim 6  wherein the binder is an inorganic silicate-based binder. 
     
     
         8 . The heating unit of  claim 7  wherein the inorganic silicate based binder comprises magnesium phyllosilicate. 
     
     
         9 . The heating unit of  claim 8  wherein the magnesium phyllosilicate is Lapointe®. 
     
     
         10 . The heating unit of  claim 4  wherein the metal reducing agent is zirconium. 
     
     
         11 . The heating unit of  claim 10  wherein the metal containing oxidizing agent comprises at least one of MoO 3  and Fe 2 O 3 . 
     
     
         12 . The heating unit of  claim 11  wherein the binder comprises an inorganic silicate based binder. 
     
     
         13 . The heating unit of  claim 12  wherein the solid fuel layer comprises by weight 10-90% zirconium, 10-90% metal containing oxidizing agent and 1-15% binder. 
     
     
         14 . The heating unit of  claim 12  wherein the solid fuel layer comprises by weight 40-70% zirconium, 10-40% metallic oxidizing agent and 3-10% binder. 
     
     
         15 . The heating unit of  claim 1  further comprising a second metal substrate contacting the solid fuel layer surface and electrically insulated from the metal substrate, the second electrode being coupled to the second metal substrate. 
     
     
         16 . The heating unit of  claim 1  further comprising a plurality of spaced solid fuel layers coated on the surface of the substrate, the second electrode being configured for selectively coupling to a select solid fuel layer. 
     
     
         17 . The heating unit of  claim 1  wherein the power supply comprises a battery. 
     
     
         18 . The heating unit of  claim 3  wherein the steel foil has a thickness ranging from 20-200 μm. 
     
     
         19 . The heating unit of  claim 1  wherein the solid fuel layer has a thickness of 20-6000 microns. 
     
     
         20 . The heating unit of  claim 1  wherein the solid fuel layer has a thickness of 20-49 μm. 
     
     
         21 . The heating unit of  claim 1  wherein the solid fuel layer has a thickness of greater than 20 μm. 
     
     
         22 . The heating unit of  claim 1  wherein the solid fuel layer has a resistance of less than 1,000,000Ω. 
     
     
         23 . The heating unit of  claim 1  wherein the voltage is greater than 3 v. 
     
     
         24 . The heating unit of  claim 1  wherein the voltage is between 3-50 v. 
     
     
         25 . The heating unit of  claim 1  wherein an activation energy of less than 25 mJ is required. 
     
     
         26 . The heating unit of  claim 1  wherein an activation energy of between about 0.10 mJ-11.25 mJ is required. 
     
     
         27 . A method of making a heating unit comprising:
 a) coating a portion of the interior surface of a conductive substrate with a slurry of solid fuel comprising a metal reducing agent, a metal containing oxidizing agent and an inorganic binder;   b) solidifying a slurry;   c) coupling a first electrode to the conductive substrate; and   d) coupling a second electrode to the surface of the solid fuel.   
     
     
         28 . The method of  claim 27  wherein the metal reducing agent is selected from at least one of the following: zirconium, titanium, aluminum and iron. 
     
     
         29 . The method of  claim 27  wherein the metal containing oxidizing agent is selected from at least one of MoO 3 , Fe 2 O 3 , MnO 2 , KClO 4  and KClO 3 . 
     
     
         30 . The method of  claim 27  wherein the binder is an inorganic silicate-based binder. 
     
     
         31 . A drug supply unit comprising:
 an electrically conductive substrate having an interior and an exterior surface;   a solid fuel layer comprising a metal reducing agent, a metal containing oxidizing agent and an inorganic binder coated on at least a portion of the interior surface of the substrate, the solid fuel layer having a solid fuel surface spaced from the interior surface of the substrate;   a drug layer capable of vaporization upon being heated to a select temperature coated on the exterior surface of the substrate;   a first electrode coupled to the substrate;   a second electrode coupled to the solid fuel surface; and   a power supply configured to be selectively coupled to the first and second electrodes to provide a voltage between the electrically conductive substrate and the solid fuel surface.   
     
     
         32 . The drug supply unit of  claim 31  wherein the electrically conductive substrate comprises a steel foil. 
     
     
         33 . The drug supply unit of  claim 31  wherein the metal reducing agent is selected from at least one of the following: zirconium, titanium, aluminum and iron. 
     
     
         34 . The drug supply unit of  claim 31  wherein the metal containing oxidizing agent is selected from at least one of MoO 3 , Fe 2 O 3 , KClO 4  and KClO 3 . 
     
     
         35 . The drug supply unit of  claim 31  wherein the binder is selected from at least one of the following: nitrocellulose, polyvinyl alcohol, diatomaceous earth, glass beads, colloidal silica, and a clay gelling agent. 
     
     
         36 . The drug supply unit of  claim 31  wherein the solid fuel layer comprises by weight 10-90% zirconium, 10-90% metal containing oxidizing agent and 1-15% binder. 
     
     
         37 . The drug supply unit of  claim 31  wherein the solid fuel layer comprises by weight 40-70% zirconium, 10-40% metallic oxidizing agent and 3-10% binder. 
     
     
         38 . The drug supply unit of  claim 31  further comprising a second metal substrate contacting the solid fuel layer surface and electrically insulated from the metal substrate, the second electrode being coupled to the second metal substrate. 
     
     
         39 . The drug supply unit of  claim 31  further comprising a plurality of spaced solid fuel layers coated on the interior surface of the substrate and a corresponding composition layer in the exterior surface, the second electrode being configured for selectively coupling to a select solid fuel layer. 
     
     
         40 . The drug supply unit of  claim 31  wherein the solid fuel has a thickness ranging from 20-49 μm. 
     
     
         41 . The drug supply unit of  claim 31  wherein the solid fuel layer has a thickness of greater than 20 μm. 
     
     
         42 . The drug supply unit of  claim 31  wherein the solid fuel layer has a resistance of less than 1,000,000Ω. 
     
     
         43 . The drug supply unit of  claim 31  wherein the voltage is greater than 3 v. 
     
     
         44 . The drug supply unit of  claim 31  wherein the voltage is between 4-30 v. 
     
     
         45 . The drug supply unit of  claim 31  wherein an activation energy of less than 11.25 mJ is required. 
     
     
         46 . The drug supply unit of  claim 31  wherein an activation energy of between about 0.18 mJ-11.25 mJ is required. 
     
     
         47 . An aerosol drug delivery device comprising:
 a housing defining an airway; and   a drug supply unit disposed in the airway, the drug supply unit comprising:   an electrically conductive substrate having an interior and an exterior surface, the exterior surface being exposed to the airway;   a solid fuel layer comprising a metal reducing agent, a metal containing oxidizing agent and an inorganic binder coated on at least a portion of the interior surface of the substrate, the solid fuel layer having a solid fuel surface spaced from the interior surface of the substrate, the interior surface of the substrate being isolated from the airway;   a drug layer capable of vaporization upon being heated to a select temperature coated on the exterior surface of the substrate;   a first electrode coupled to the substrate;   a second electrode coupled to the solid fuel surface; and   a power supply configured to be selectively coupled to the first and second electrodes to provide a voltage between the electrically conductive substrate and the solid fuel surface.