Abstract:
An extraction cleaning machine comprising dispensing and recovery systems, the dispensing system including a system for generating heat with an exothermic reaction upon activation for heating the cleaning solution prior to dispensing of the cleaning solution onto a surface. The cleaning solution dispensing system comprises a cleaning solution reservoir to which the heat of the exothermic reaction can be added and a dispenser. The heat of the exothermic reaction can also be added in line to the cleaning solution between the cleaning solution reservoir and the dispenser. The recovery system includes a suction nozzle, a recovery tank and a vacuum source for drawing recovered liquid from the suction nozzle into the recovery tank. A method of cleaning a surface comprises the steps of heating a cleaning solution by an exothermic chemical reaction, applying the cleaning solution to the surface and recovering the cleaning solution from the surface.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application is a divisional of U.S. application Ser. No. 10/065,480, filed Oct. 22, 2002, now U.S. Pat. No. 7,153,371, issued Dec. 26, 2006 and claims the benefit of U.S. Provisional Application No. 60/348,103, filed on Oct. 23, 2001. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to extraction cleaning. In one of its aspects, the invention relates to an extraction cleaner in which a cleaning solution is heated by an exothermic reaction. In another of its aspects, the invention relates to a method of cleaning a floor surface such as a carpet with a heated cleaning solution. In another of its aspects, the invention relates to heating a cleaning solution in an extraction cleaner by an exothermic reaction and applying the heated solution to a floor surface for cleaning. 
   2. Description of the Related Art 
   An extraction cleaning machine having a heater for dispensing a heated cleaning solution is disclosed in U.S. Pat. No. 6,131,237, incorporated herein by reference in its entirety. 
   U.S. Pat. No. 4,522,190 discloses a flexible electrochemical heater comprising a supercorroding metallic alloy powder dispersed throughout a porous polyethylene matrix. Upon the addition of a suitable electrolyte fluid, such as a sodium chloride solution, heat is rapidly and efficiently produced. The electrochemical heater element can be contained in a porous envelope through which fluid can pass for reacting with the alloy powder to generate heat while keeping the alloy powder contained within the envelope. 
   U.S. Pat. No. 5,163,504 discloses a package heating device in the form of a membrane holding a quantity of microscopic spheres containing a hydrous substance such as water or saline solution. The membrane further contains an anhydrous substance such as magnesium sulfate proximate to the spheres containing the water or saline solution. The anhydrous substance can also be contained in spheres. To activate the heating device, the spheres are mechanically broken to release the substances contained therein. The blending of the hydrous and anhydrous substances within the membrane generates an exothermic reaction releasing heat into the container associated with the heating device. 
   A container having an integral module for heating the contents is disclosed in U.S. Pat. No. 5,979,164. By way of example, the integral module functions as a cap for the container and comprises a sealed cavity holding the reactants for an exothermic reaction. The reactants are physically separated until a user wishes to initiate the exothermic reaction. In use, a liquid is placed in the container and the module is placed on the container in contact with the liquid. The reactants are then mixed within the sealed cavity to generate the exothermic reaction, the resultant heat being transferred from the module to the liquid in the container while the reactants remain fluidly isolated from the liquid. 
   U.S. Pat. No. 6,029,651 discloses a cup enclosing an aqueous sodium acetate solution and a metallic activator strip in a cavity formed between inner and outer walls of the cup. The aqueous sodium acetate solution is supercooled. The activator strip is a flexible metal strip accessible to a user through a flexible portion of the outer wall of the cup. When the user flexes the activator strip, it initiates a crystallization of the sodium acetate with an accompanying generation of heat, which can then be transferred to the contents of the cup. The sodium acetate is returned to the supercooled condition by heating above its melting point and air cooling. Flexing of the activator strip will again initiate crystallization. This cycle can be repeated indefinitely, making the cup reusable for heating fluids. 
   SUMMARY OF THE INVENTION 
   According to an embodiment of the invention, a kit for cleaning a surface to be cleaned comprises a cleaning solution and an extraction cleaner having a housing, a cleaning solution dispensing system, a fluid recovery system and an exothermic heating system adapted to be placed in heat exchange relationship with the cleaning solution dispensing system to heat the cleaning solution to a temperature above room temperature for application to the surface to be cleaned. The exothermic heating system can comprise at least one reagent that is adapted to generate an exothermic reaction. When the cleaning solution is added to the cleaning solution dispensing system, the exothermic heating system is placed in heat exchange relationship with the cleaning solution dispensing system and the exothermic heating system is activated to generate an exothermic reaction, the cleaning solution is heated, whereby the cleaning solution thus heated can be applied to a surface to be cleaned for enhanced cleaning. 
   According to another embodiment of the invention, the exothermic heating system can comprise at least one compound or composition that can generate heat when transforming from one phase to another. The phase change can include changing phase from a liquid to a solid or from one solid phase to another. The exothermic heating system can also comprise a sodium acetate solution and can further include an activator that can be introduced into the sodium acetate solution. The activator can be in the form of a metal. 
   In another embodiment, the exothermic heating system can comprise two or more reagents that, when combined, undergo an exothermic reaction. The two or more reagents can include a base and an acid that undergo an exothermic reaction when combined. The exothermic heating system can comprise a mild acid in the cleaning solution tank and the cleaning solution can have a pH less than 7. The acid can be selected from the group consisting of stearic acid, citric acid and phosphoric acid. The base can be selected from the group consisting of diethanolamine, triethanolamine, sodium hydroxide and potassium hydroxide. A reaction product of the mild acid and base can be a surfactant that becomes part of the cleaning solution. 
   According to another embodiment of the invention, the exothermic heating system can comprise two or more reagents that, when combined, undergo an exothermic reaction. The two or more reagents can include a base and an acid that undergo an exothermic reaction when combined. The exothermic heating system can comprise a mild acid in the cleaning solution tank and the cleaning solution can have a pH less than 7. The acid can be selected from the group consisting of stearic acid, citric acid and phosphoric acid. The base can be selected from the group consisting of diethanolamine, triethanolamine, sodium hydroxide and potassium hydroxide. A reaction product of the mild acid and base can be a surfactant that becomes part of the cleaning solution. 
   According to another embodiment of the invention, an extraction cleaner can comprise a housing, a cleaning solution dispensing system, a fluid recovery system and a heater in heat exchange relationship with the cleaning solution dispensing system to heat the cleaning solution. The heater can include a double wall receptacle having an outer wall and an inner wall, the inner wall defining the cleaning solution tank for storing the cleaning solution, the inner and outer wall defining a reagent cavity, and an exothermic heating system comprising at least one reagent and at least one activator. The at least one activator can be integral with the outer wall of the reagent cavity for generating heat through an exothermic reaction in the reagent cavity. When heat is generated in the reagent cavity by the exothermic heating system, the heat can be transferred from the reagent cavity to the cleaning solution in the cleaning solution tank through the inner wall of the heater. 
   According to yet another embodiment of the invention, an extraction cleaner can comprise a housing, a cleaning solution dispensing system, a fluid recovery system and a heater in heat exchange relationship with the cleaning solution dispensing system to heat the cleaning solution. The heater can include a double wall receptacle having an outer wall and an inner wall, the inner wall defining the cleaning solution tank for storing the cleaning solution, the inner and outer wall defining a reagent cavity, an exothermic heating system comprising at least one reagent for generating heat through an exothermic reaction in the reagent cavity and at least one anode and one cathode located within the reagent cavity. When heat is generated in the reagent cavity by the exothermic heating system, the heat can be transferred from the reagent cavity to the cleaning solution in the cleaning solution tank through the inner wall of the heater. The exothermic heating system can be regenerated by applying an electric potential across the at least one anode and the at least one cathode. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
       FIG. 1  is a perspective view of an extraction cleaner according to the invention. 
       FIG. 2  is a perspective view of a clean solution tank of the extraction cleaner of  FIG. 1  illustrating one embodiment of the invention. 
       FIG. 3  is a schematic cross-sectional view of the clean solution tank illustrated in  FIG. 2 . 
       FIG. 4  is a cross-sectional view of a clean solution tank according to a second embodiment of the invention. 
       FIG. 5  is a flowchart of an exothermic reaction heating cycle according to the embodiment of  FIGS. 2 and 3 . 
       FIG. 6  is a flowchart of an exothermic reaction heating cycle according to the embodiment of  FIG. 4 . 
       FIG. 7  is a schematic representation of an exothermic reaction heating process according to a third embodiment of the invention. 
       FIG. 8  is a schematic representation of an exothermic reaction heating process according to a fourth embodiment of the invention. 
       FIG. 9  is a schematic representation of an exothermic reaction heating process according to a fifth embodiment of the invention. 
       FIG. 10  is a schematic representation of an exothermic reaction heating process according to a sixth embodiment of the invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIG. 1 , an upright extraction cleaner  10  according to the invention comprises an upright handle  12  and a base  14 . A clean solution tank  18  is carried by the upright handle  12 . The base  14  is partially supported by wheels  16  and by suction nozzle  20 . A fluid dispensing nozzle  22  is disposed on an underside of the base  14  to the rear of the suction nozzle  20  for dispensing a cleaning solution on a surface being cleaned. 
   Extraction cleaning using exothermic chemical heat according to the invention is not limited to the upright extraction cleaner  10  of  FIG. 1 , but also includes application in a canister-type or portable hand-held extraction cleaner. The extraction cleaner according to the invention includes a fluid dispensing system for applying a cleaning solution to a surface being cleaned, and further includes a fluid recovery system for removing soiled solution from the surface being cleaned. These systems are described in further detail in U.S. Pat. Nos. 6,125,498, 6,131,237 and 6,167,586 and U.S. patent application Ser. No. 09/755,724, filed Jan. 5, 2001, all of which are commonly owned with this application and are incorporated herein by reference in their entirety. 
   Referring now to  FIGS. 2-3 , clean solution tank  18  comprises a double-walled receptacle formed by an inner wall  52  and an outer wall  50  defining a cavity  54  therebetween. The inner wall  52  defines a chamber  56  for holding a cleaning solution. Chamber  56  is filled with cleaning solution through fill opening  70 , which is selectively sealed with cap  72 . The cavity  54  defined between the inner wall  52  and the outer wall  50  contains a reactant fluid mixture  100 . Upon the blending of the reactants contained in the fluid mixture  100  within the cavity  54 , an exothermic reaction ensues. The heat generated by the exothermic reaction is then transferred through the inner wall  52  to a cleaning solution held within the chamber  56  for dispensing by the extraction cleaner. The cleaning solution is dispensed through tube  74  and valve assembly  76  or the solution dispensing system of the extraction cleaner. In one embodiment, the outer wall  50  of the receptacle is thermally insulated to preclude the loss of heat to the atmosphere and to contain the heat generated by the exothermic reaction in the solution within chamber  56  of the clean solution tank. The double wall receptacle forms a heat exchanger between the cavity  54  and the chamber  56  for transfer of the exothermic hear of reaction from the cavity  54  to the chamber  56 . 
   The reactants contained within the cavity  54  between the inner and outer walls  50 ,  52  are combined to initiate the exothermic reaction. The reactants are capable of separation by the application of opposing electrical charges  60  applied to an anode and cathode  64 ,  66  mounted within the cavity  54  for emersion in the fluid  100 . The anode and the cathode  64 ,  66  are positioned remotely from one another to maximize the polarization of the reactant fluid  100  and resulting separation of the reactive components. Well-known heat pumps use similar systems in which heat energy is stored in separated components for release of heat energy upon combining of components. 
   The reactant fluid  100  can be rejuvenated by the application of the electrical potential between the anode  64  and cathode  66  after each use of the solution tank  18 , or during pauses in use of the extraction cleaner. An advantage of the exothermic heating is found in the addition of thermal energy to the cleaning solution without the need to expend additional electrical energy during the cleaning process. The available electrical capacity can then be used in other components of the extraction cleaner, such as an agitation brush, suction source, or resistance heater. A resistance heater, such as an in-line heater or an in-tank heater, can be more effective in heating the cleaning solution to a more optimum temperature when used in combination with exothermic heating of the invention. 
   In a further embodiment of the invention shown in  FIG. 4 , the cavity  154  between the inner wall  152  and outer wall  150  of the solution tank  118  contains, by way of example, an aqueous sodium acetate solution  200  and a metallic activation strip  160 . The activation strip  160 , preferably formed of aluminum, is positioned adjacent a flexible portion  165  of outer wall  150 . A user flexes the activation strip to initiate crystallization of the sodium acetate, which is an exothermic reaction. Such a system is disclosed in U.S. Pat. No. 6,029,651, which is incorporated herein by reference. As the sodium acetate crystallizes exothermically, it transfers heat to the cleaning solution within the solution tank  118 . After each use, the sodium acetate must be returned to its liquid state. This is commonly accomplished by placing the tank  118  in boiling water or heating in an oven. As the sodium acetate cools, it remains in a supercooled liquid state, storing the energy that it will later release during crystallization. The solution tank  118  is thus reusable. 
     FIGS. 5-6  are flow charts describing the cycle of use of the embodiments depicted in  FIGS. 2-4 . Referring first to  FIG. 5 , the reactants are blended in step  90  to initiate an exothermic reaction. The reactants then transfer heat in step  92  to the cleaning solution contained within the solution tank. The heated cleaning solution is then dispensed by the extraction cleaner in step  94 . The soiled solution is then recovered from the surface being cleaned in step  96 . The reactants are then returned to their separated state in step  98  by the application of an electrical charge, ready for blending the next time the exothermic reaction is needed to heat a cleaning solution. Alternatively, the spent exothermic solution can be removed from the cavity  54  and discarded and new reactants can be added to the cavity  54  when further heating of the cleaning solution is desired. Alternatively, the spent exothermic solution can be removed from the cavity  54  and separated into its components in an operation outside of the cavity  54 . The separated components can then be returned to the cavity  54  when further heating of the cleaning solution is desired. 
   Referring now to  FIG. 6 , the process is begun by filling the tank  56  with water or detergent cleaning solution. The first step in the cleaning process is initiating crystallization in step  190  of the sodium acetate solution. The crystallization process is an exothermic reaction, the heat of which is transferred in step  192  to the cleaning solution. The heated cleaning solution is then applied to the surface being cleaned in step  194 . The soiled solution is then recovered in step  196 . The crystallized sodium acetate is then returned to its supercooled liquid solution form in step  196  by heating above its melting point and air cooling. It can thus be used repeatedly for heating by exothermic reaction. 
   In a third embodiment of the invention depicted in  FIG. 7 , a clean solution tank  318  in an extraction cleaner is filled with a cleaning solution  302 . The cleaning solution can be at room temperature, or preferably at an elevated temperature. An exothermic heating system  300  according to the invention is then added to the cleaning solution  302  in the clean solution tank  318 . The exothermic heating system  300  reacts exothermically within the cleaning solution  302  to further elevate the temperature of the cleaning solution  302 . The heated cleaning solution is thus ready for dispensing from a dispensing nozzle  370  onto a surface to be cleaned, the elevated temperature of the solution acting to more effectively remove soil from a surface. 
   Various combinations of additives that react exothermically are anticipated for use in this and other embodiments of the invention. One example is the addition of a mild acid, such as stearic acid, to the cleaning solution in the solution tank to lower the pH of the cleaning solution to less than 7, and preferably to the range of 4-5. The exothermic reaction is initiated by then adding a mild caustic such as triethanolamine, with a pH greater than 7, and preferably in the range of 8-9. This combination has the further beneficial effect of producing a surfactant that becomes part of the cleaning solution. Other acid/base combinations are equally anticipated for use, including citric or phosphoric acids, and diethanolamine, sodium hydroxide or potassium hydroxide. More aggressive exothermic reactions are available by the addition of metallic exothermic heating systems such as aluminum, which react with the caustic compounds. All of these compounds can be used either within the cleaning solution or, in some cases, in the cavity  54  of the embodiment of  FIG. 3 . 
   In the embodiment shown in  FIG. 7 , additional exothermic heating system  300  in the form of a booster can be added to the cleaning solution as it is being dispensed so that the ongoing exothermic reaction further elevates the temperature of the applied cleaning solution as it is being dispensed onto the carpet or floor surface. The booster can be added directly to the cleaning solution or can be passed through a heat exchanger to indirectly transfer heat from the booster to the cleaning solution in line. 
   In the embodiment of  FIG. 7 , the exothermic heating system added to the cleaning solution can be configured or selected to behave in a time-release fashion. The exothermic reaction thereby takes place over an extended period of time and maintains the cleaning solution at an elevated temperature for a longer period of time. 
   Referring now to  FIG. 8 , in a fourth embodiment of the invention, the exothermic reaction generated by the addition of exothermic heating system  400  to a cleaning solution within the solution tank  418  elevates the temperature of the cleaning solution. This elevated temperature may yet remain below the optimal temperature determined for the cleaning solution to be effective on a surface to be cleaned. The heating effect of the exothermic reaction is then supplemented by the injection of heat energy into the cleaning solution by an in-line heater  480 , having an electrical power source  460 , fluidly connected between the clean solution tank  418  and a dispensing nozzle  470  on the extraction cleaner. 
   In a fifth embodiment of the invention shown in  FIG. 9 , the exothermic reaction generated by the addition of exothermic heating system  500  to a cleaning solution within the solution tank  518  elevates the temperature of the cleaning solution. The energy released by this exothermic reaction is supplemented by an in-tank heater  580 , having electrical power source  560 , positioned within the solution tank  518  to elevate the temperature of the cleaning solution to an optimal temperature for effectiveness of the cleaning solution on the surface to be cleaned. 
   Referring to  FIG. 10 , in a sixth embodiment of the invention, the exothermic heating system  600  comprises a supercorroding metallic alloy powder dispersed throughout a porous polyethylene matrix and contained by a porous envelope, for reaction with an appropriate electrolytic solution. An example of this system is disclosed in U.S. Pat. No. 4,522,190, which is incorporated herein by reference. In  FIG. 10 , the system  600  is immersed in the cleaning solution  602 . The cleaning solution  602  penetrates the porous envelope to react with the system  600 . It is anticipated that the system  600  can be placed in the cleaning solution  602  in the solution tank  618  shortly before dispensing the cleaning solution  602  through a dispensing nozzle  670 . 
   The invention has been illustrated with respect to a particular upright extraction cleaning machine. The invention is applicable to all types of extraction cleaning machines, including commercial cleaning machines as well as domestic cleaning machines, canister extractors, hand held portable extractors. 
   While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation. Reasonable variation and modification are possible within the forgoing description and drawings without departing from the spirit of the invention, which is embodied in the appended claims.