Patent Publication Number: US-2010122541-A1

Title: Hot air generating tool

Description:
BACKGROUND OF THE INVENTION 
     Drying machines, for example of the infrared type, are currently known for the industrial drying of one or more painted bodies, for example a component of a vehicle body or an entire vehicle body, for example of a car, and are inherently expensive in themselves and also in terms of management and maintenance. 
     For hobby work, these industrial solutions are inherently unfeasible, and a person who has painted one or more bodies or surfaces, for example by means of an airbrush or a paint gun to be associated with an air compressor, must allow the painted bodies to dry in the air by natural convection, or use an ordinary hairdryer, improperly consuming electric power and risking desiccation of the painted surface. 
     SUMMARY OF THE INVENTION 
     The aim of the present invention is to provide a tool which generates hot air by using compressed air and can be connected easily to a compressor of a known type. 
     Within this aim, an object of the present invention is to provide a tool which is easy to provide and use and is also cheap. 
     Another object of the present invention is to provide a hot air generating tool which can be manufactured with known systems and technologies. 
     This aim and these and other objects, which will become better apparent hereinafter, are achieved by a hot air generating tool, comprising a tubular body for aspirating and discharging drying air, with which means for heating said air and a handle are associated, characterized in that said air heating means are constituted by a Ranque-Hilsch vortex tube device supplied with compressed air. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further characteristics and advantages of the invention will become better apparent from the following detailed description of a preferred but not exclusive embodiment thereof, illustrated by way of non-limiting example in the accompanying drawings, wherein: 
         FIG. 1  is a sectional view of a tool according to the invention; 
         FIG. 2  is a perspective view of a use of the tool according to the invention; 
         FIG. 3  is a schematic sectional view of the operation of the vortex tube device which is a part of the tool according to the invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to the figures, a hot air generating tool according to the invention is generally designated by the reference numeral  10 . 
     The hot air generating tool  10  comprises a tubular body  11  for aspirating and discharging drying air, with which means for heating the air and a handle  12  are associated. 
     The air heating means are constituted by a Ranque-Hilsch vortex tube device  13 , which is supplied with compressed air. 
     The Ranque-Hilsch vortex tube device  13 , which is of a per se known type, is integrated in the handle  12 . 
     The vortex tube device  13  comprises a cylindrical chamber  14  in which compressed air is injected in a radial direction from a lateral port  15 , such air arriving from a compressor of a known type, which is not illustrated for the sake of simplicity. 
     A first tubular cylindrical element  16  for feeding hot air toward the tubular body  11  protrudes from the chamber  14 , coaxially thereto, at one end, and a second tubular element  17 , which is shorter than the first element  16 , for discharging cold air protrudes from the opposite side. 
     A valve  18  for adjusting the flow-rate of compressed hot air is provided at the end of the first tube  16 . 
     The first tube  16  passes through the handle  12  and leads into the tubular body  11  for aspirating and discharging air, while the second tube  17  expels the cold air into the environment, or as an alternative into a disposal tube designed to move the cold air flow away from the user. 
     The handle  12  is also designed to protect the user against the cold that exits from the second tube  17  and from the heat emitted by the first tube  16 . 
     The tubular body  11  comprises: a first central part  20 , with which the handle  12  is rigidly coupled; a second intake part  21 , with a frustum-shaped internal surface  22  which tapers toward the inside of the tubular body  11  and a debris retention grille  23 ; a third emission part  24 , with an outer diverging portion  25  to provide a Venturi effect. 
     The third part  24  is screwed to the first part  20  by means of two corresponding threaded portions, an internal thread  26  on the first part  20  and a complementary external thread  27  on the third part  24 , in order to adjust the temperature by increasing or decreasing the Venturi effect. 
     By turning the third part  24  in one direction or in the opposite direction, the pressurized hot air stream that exits from the first tube  16  is throttled, thereby modifying the temperature of the air that exits from the tubular body  11 , as shown by way of example in  FIG. 3 . 
     The vortex tube device  13 , as mentioned, is of a per se known type, and is used generally in a wide range of applications in the localized cooling of machines, assembly lines and industrial processes. 
     In the present invention, the generated hot air of the tube device  13  is used instead of the cold air. 
     The operating principle of the tube device  13  is as follows. 
     The compressed air is injected radially into the chamber  14 , where a vortex is generated; such vortex produces the dynamic separation or extraction of molecules with high kinetic energy (i.e., at high temperature) from molecules with lower kinetic energy (and therefore at a lower temperature). 
     In this manner, two separate air streams, a hot one and a very cold one, are generated starting from a flow of compressed air. 
     Part of the hot air (which therefore moves at a higher speed than the cold air) is made to exit from the first tube by means of a conical end nozzle, shown schematically in  FIG. 3  and designated therein by the reference numeral  30 , and an adjustment valve  18 ; the conical nozzle  30  allows the outflow of the hot outer stream  31  and diverts in the opposite direction the cold inner stream  32 . 
     The cold inner stream  32  is thus forced in countercurrent at the opposite end toward the chamber  14  and from there toward the second tube  17 . 
     The pressurized hot air that exits from the first tube  16  can reach 110° C. 
     The control valve  18  located in the end of the first tube  16  allows to adjust the temperature and quantity of the air. 
     In practice it has been found that the invention thus described solves the intended aim and objects. 
     In particular, the present invention provides a tool for generating hot air by using compressed air which can be connected easily to known types of compressor, so as to utilize the characteristics of the Ranque-Hilsch tube device. 
     Further, the present invention provides a tool which is easy to provide and use, as well as cheap, also in that it does not use electric power directly, except for the power needed to run the compressor. 
     Further, the tool is lightweight and has no moving parts, and is therefore scarcely demanding to handle for a user who has to hold it for a long period of time. 
     Further, the invention provides a drying tool which can be purchased and managed easily even by a private individual for hobby-related purposes and can also be used at an industrial level by appropriately adapting its dimensions. 
     Moreover, the present invention provides a tool for generating hot air which can be manufactured with known systems and technologies. 
     The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims; all the details may further be replaced with other technically equivalent elements. 
     In practice, the materials employed, so long as they are compatible with the specific use, as well as the dimensions, may be any according to requirements and to the state of the art. 
     The disclosures in Italian Patent Application No. PD2007A000182 from which this application claims priority are incorporated herein by reference. 
     Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.