Patent Publication Number: US-6216359-B1

Title: Gas fired garment dryer

Description:
TECHNICAL FIELD 
     The present invention relates to drying garments and more particularly to gas fired driers for garments such as shoes, boots and gloves. 
     BACKGROUND OF THE INVENTION 
     Various apparatus have been developed for drying wet garments, especially footwear and gloves. One such device is disclosed in U.S. Pat. No. 3,417,482 granted on Dec. 24, 1968 to the present inventor, Gene W. Peet. This device has been popular, especially with those who work outdoors in adverse weather. The drier makes use of electric resistance heating elements and thermo-convection induced air movement for even, uniform drying of boots, shoes and gloves. However, dependency on availability of electrical current impedes use of the driers. Those who must camp outdoors or stay for extended periods in areas without the benefit of a generator or other source of electrical current must often simply tolerate wet footwear. Efforts to dry a wet pair of leather boots by placing them next to a campfire often result in ruined boots. This is so since it is well known that boots and shoes should be dried from the inside out, and that overheating can damage the garments. 
     Thus, while drying efficiency is good especially in those driers using simple warm air convection currents (as provided by the boot and shoe drier cited above), a need has remained for a drier that will operate where no electrical current is available. 
     An object of the present invention is therefore to provide a garment drier that does not require connection to electrical current for effective operation. 
     A further object is to provide such a drier that makes use of convection air currents for drying purposes. 
     A still further object is to provide such a drier that may be used with a conventional combustible gas such as propane that is readily available in pressurized tanks. 
     The above and still further objects and advantages will become apparent from the following description which, taken with the appended drawings and claims, describe the best mode for carrying out the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the invention are described below with reference to the following accompanying drawings. 
     FIG. 1 is a perspective view of a gas fired garment drier exemplifying a preferred form of the invention; 
     FIG. 2 is a sectional view taken along line  2 — 2  in FIG. 1; 
     FIG. 3 is a fragmented enlarged bottom plan view; 
     FIG. 4 is an enlarged partially fragmented view of the gas burner and heat exchanger; 
     FIG. 5 is an exploded perspective view of the gas burner and a fragmented part of the heat exchanger; 
     FIG. 6 is a partially sectioned view of the gas burner; and 
     FIG. 7 is a fragmented sectional view of an air conduit and the heat exchanger. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     This disclosure of the invention is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8). 
     General aspects of the present gas fired garment drier will be given below, with reference to the appended drawings. Further detailed discussion will then follow. 
     In a first aspect, a gas fired garment drier  10  is generally comprised of a base  12  with an air conduit  14  on the base  12  including an internal air passageway  16  leading from a bottom end  18  to a top end  20 . A gas burner  22  is positioned adjacent the bottom end  18 . A heat exchanger  24  is situated adjacent the gas burner  22  and leads into the air conduit  14  and the air passageway  16 . The heat exchanger  24  includes a convection air duct  26  that extends into the air conduit  14  within the air passageway  16 . A garment support  28  is provided on the air conduit  14  adjacent the top end  20 . 
     In another aspect, the drier  10  generally includes a hollow base  12  with a substantially upright air conduit  14  having an open bottom end  18  mounted to and opening into the hollow base  12  and including an internal air passageway  16  leading to an open top end  20 . A gas burner  22  is mounted within the base. A heat exchanger  24  is also mounted within the base adjacent the gas burner. The heat exchanger  24  includes a convection air duct  26  extending into the air conduit  14  within the air passageway  16 . A garment support  28  is provided on the air conduit  14  adjacent the open top end  20 . 
     Another aspect of the present drier  10  generally includes a base  12  and a pair of elongated substantially upright air conduits  14  mounted to the base  12 , each including an internal air passageway  16  leading to a top end  20 . A gas burner  22  is mounted to the base  12  and includes a burner tip  30 . A gas valve and pressure regulator  31  is connected to the gas burner and configured to be fitted to a source of pressurized combustible gas G. A heat exchanger  24  is situated adjacent the gas burner and includes a heat collector plenum  32  enclosing the burner tip  30 . The heat collector plenum  32  includes branch tubes  33  that lead toward the upright air conduits  14 . Convection air ducts  26  are connected to the branch tubes  33  and extend into the air conduits  14  within the air passageways  16 . The convection air ducts  26  include open bottom and top ends  34 ,  36 . The open bottom ends  34  are situated adjacent respective bottom ends  18  of the air conduits. The branch tubes  33  open into respective convection air ducts  26  at points  38  between the open bottom ends  34  and the open top ends  36  of the convection air ducts  26 . Garment supports  28  are situated adjacent the top ends  20  of the air conduits  14 . 
     Referring now to specific preferred constructions of components in preferred forms of the present drier  10 , reference is first made to FIGS. 1-3. There, a preferred example of the base  12  is shown. The preferred base is constructed of molded plastic in a hollow configuration. A bottom surface  40  of the base  12  is generally planar to support the base on any appropriate substantially flat support surface. In the illustrated example, sufficient space is provided within the base above the bottom surface  40  to receive the burner and heat exchanger components. 
     It is preferred, as illustrated in the drawings, that two air conduits  14  be mounted on the base  12 . The air conduits are most preferably generally upright to facilitate air movement by way of thermo-convection induction (the tendancy for warm air to raise) and may vary in height, depending upon the garment to be dried. High top boots, for example may require long air conduits  14 . Gloves and shoes may be dried using shorter conduits. To accommodate such variations, the conduits may be provided in separable sections. 
     In preferred forms, the air conduits are  14  are open at the bottom ends  18  and top ends  20  as well. They may be formed of the same plastic material as the base, and be affixed or releasably mounted thereto. The conduits  14  may be circular in cross section as shown, or other configurations could be used without departing from the scope of the invention. 
     The top ends  20  of the air conduits are provided with garment supports  28  (FIG. 1) that may be configured to accommodate a particular garment. In the illustrated example, the supports  28  are configured to support and direct heated convection air into boots or shoes. Gloves may also be placed over the illustrated supports. Alternatively, other supports may be provided that are particularly adapted to aid air flow through gloves or mittens. For such alternative uses, it is preferred that the supports  28  be removable or formed on removable sections of the air conduits  14  to facilitate interchanging various forms of garment supports. It is also possible that the top conduit ends  20  could be used alone as the garment supports  28 . 
     FIG. 1 illustrates a conventional gas bottle or canister G that is attached to the gas burner  22  by way of a valve and burner regulator  31 , and a conventional gas delivery hose. It is preferred that the combustible gas be of a conventional, readily available type such as propane that is commonly used for heat and lighting. The valve and pressure regulator may also be of a conventional form, pre-set to release gas at a low pressure (within a range of approximately 0.5 to 5 psi and most preferably at approximately 0.6 psi). Propane, released through the present burner at 0.6 psi will produce approximately 500 btu. in preferred forms of the drier  10 . 
     Gas enters the burner  22  through a conventional gas fitting  42  (FIGS. 5,  6 ) that leads to a nozzle  43 . The nozzle  43  may be formed of brass or other appropriate metal or ceramic and include a discharge opening  44  that is provided according to the type of gas and pressure being used. Propane, delivered at approximately 0.6 psi may best be used with a discharge opening of approximately 0.007 inches. 
     An air and gas mixing housing  45  may be provided to enclose the nozzle  43 . The housing  45  may be formed of a metal tube that, as shown, may be threaded onto the nozzle. Air and combustible gas mix within the housing through provision of air bleed holes  46 . Several of the bleed holes may be provided at substantially equally spaced angles about the housing to introduce air into the mixing housing  45 . In one working example, 4 holes were formed through the housing, each hole having a diameter of approximately 0.17 inches. Air is drawn into the mixing chamber by a venturi effect from the pressurized gas discharged through the nozzle. 
     The burner tip  30  is situated downstream of the mixing chamber, adjacent the heat exchanger  24 . The tip may be formed of a metal tube, and be mounted to the mixing housing as illustrated in FIG. 6. A flame diffuser  50  is preferably included in the gas burner adjacent to and more preferably within the burner tip  30 . The preferred flame diffuser  50  is comprised of a heat resistant open mesh screen that spans the burner tip. The diffuser has the effect of stabilizing the gas flame, forming somewhat of a “bubble” shape at the discharge end of the tip. 
     The heat exchanger  24 , in preferred forms is formed by a heat conductive tube, preferably of a heat conductive material such as aluminum. The preferred heat exchanger includes the heat collector plenum  32  which encloses the gas burner, and more particularly the burner tip  30  at its outward end. The plenum  32  is inwardly open, to form a chamber about the flame when the unit is operating. The interior walls of the plenum are formed so the flame does not impinge on any surface and thereby discourages spot heating of the collector surfaces. 
     In the illustrated preferred example, the plenum  32  is comprised of a “T” that may be produced by a copper plumbing fitting. The leg of the “T” fits over the burner tip  30 . The cross part of the “T” mounts the branch tubes  33 , which may be formed of copper tube that is soldered, welded, or otherwise affixed to the plenum  32 . Each of the branch tubes  33  includes an open internal bore leading substantially horizontally toward an associated air conduit  14  and convection air duct  26 . 
     The heat exchanger preferably includes a flame view port  47  formed therein adjacent the burner. A flame will be visible through the port when the unit is operating and the user can easily see when ignition takes place when the unit is fired. To this end, the base  12  (FIGS.  1 , 2 ) preferably includes a flame viewing aperture  48  that is substantially aligned with flame view port  47  to facilitate visual monitoring of the flame while the unit is resting on a support surface. 
     It is noted that gasses in the burner may be ignited as graphically indicated in FIG. 7, through an ignition touch hole  49  (FIG. 3) formed on the bottom side of the heat exchanger just downstream of the burner tip. Other forms of ignition may be used, and other locations may be provided for ignition purposes. For example, it is entirely feasible to ignite the gasses through the view port  47 . 
     The branch tubes  33  are provided to conduct the heated exhaust gasses from the flame at the burner tip  30  into the convection air ducts  26 . The exhaust gasses enter the convection air ducts  26  at points  38  that are above the air duct bottom ends  34 , and below the air duct top ends  36 . The gasses, being warmer than the surrounding air, will naturally move upwardly, producing a convection air flow upwardly within the ducts, along with air pulled into the ducts through the open duct bottom ends  34 . The spent gasses mix with the fresh air inside the ducts  26 , heating the air and moving upwardly in a thermo-convection induced airflow to be discharged through the open top ends of the conduits  14 . 
     Referring in greater detail to preferred forms of the convection air ducts  26 , attention is drawn to FIG. 2 of the drawings. The air ducts may be considered as part of the heat exchanger. Each duct  26  includes an elongated portion  52  that is substantially centered within the associated air conduit  14 . The ducts  26  are also preferably formed of heat conductive tubes such as copper tubing and may be fitted to the branch tubes by “T” fittings which define the open entry points  38 , and the open bottom ends  34  of the ducts. 
     In preferred forms, the ducts  26  may be within a range of approximately 4 inches to 9 inches in length. The greater parts of the duct lengths are situated within the conduits  14  to best initiate upward air current. Thus the open top ends  36  of the ducts  26  positioned upwardly within the conduits but below the open top ends  20  of the associated conduits  14  to allow upward passage and mixing of warmed air currents. 
     The open bottom ends  34  of the ducts are preferably situated below the burner  22  and somewhat below the open bottom ends of the conduits  14 . This arrangement encourages intake of the lowest temperature air (within the base) through the bottom duct ends, while somewhat warmer air is free to enter the space between the ducts  26  and interior walls of the conduits  14  through the slightly upwardly spaced bottom conduit ends  18 . 
     As exemplified in FIGS. 2,  3 , and  5 , convection ducts  26  are preferably centered within the associated conduits  14  and within elongated open ended heat shields  54 . The heat shields may be formed of an appropriate heat metal such as aluminum with inward reflective surfaces at least partially encircling the elongated portions of the heat conductive duct tubes within the air conduits. The heat shields form elongated axial internal air spaces  56  (FIGS. 2,  3 ) between the heat conductive tube and external air spaces  58  between the heat shield and air conduit. The heat shields are useful to protect the conduits  14  from any potential excessive heat, and function well to channel warmed air upwardly within the conduits and out the open top ends  20 . 
     Positioning wires or rods  60  may be provided to extend through the heat shields  54  and convection air ducts to engage side walls of the conduits  14  and hold the shields  54  and ducts  26  in substantial concentric relation. The rods  60  may be flexible to hold the shields and convection air ducts longitudinally in position by spring action against the conduit walls. 
     In operation, the user may first place garments, for example a pair of boots over the supports  28 . Most preferably, the boots are placed upside down (with soles facing upwardly) over the supports, such that the supports are received inside the boots. 
     The user may attach the valve and pressure regulator to a pressurized gas bottle or canister G as shown in FIG.  1 . The attachment between the gas bottle and burner is now completed. 
     Next, the user may open the valve  31  to allow pressurized gas to flow from the canister G, through the nozzle  43  and into the gas and air mixing housing  45 . Air will enter by venturi action through the bleed holes  46  to mix with the gas. The mix will then pass through the burner tip. This combustible mixture may be ignited. 
     Ignition may be accomplished using a match or other appropriate igniter, placed next to the touch hole  49 . A small “bubble” of flame will become visible through the view port  47  and the viewing aperture  48  once proper ignition has taken place. The diffuser  50  will function through ignition and as combustion continues, to diffuse the gas and air mix across the burner tip and aid to produce a small but stable flame. 
     It is preferred that the small flame not impinge against the adjacent interior surfaces of the plenum in order to avoid overheating of the heat exchanger  24 . However, the flame will warm the air within the plenum  32  and heat will also transfer by conduction through the heat exchanger, to the branch tubes and convection air ducts  26 . 
     The heated, spent gasses will travel along the branch tubes  33  and enter the convection air ducts  26  at the opening points  38 , just above the open bottom duct ends  34 , then travel upwardly due to the natural tendency for heated air to raise. Upward movement of the heated air inside the ducts  26  causes unheated air to be drawn into the open bottom duct ends  34  from the environment within the base  12 . This air mixes with incoming exhaust gasses and is also heated by the walls of the ducts, and will therefore also raise upwardly in the ducts. Continuous upward warm dry air movement is thus produced so long as the flame continues to burn. 
     The heated air and spent gasses exit through the top open ends of the ducts  26  in a positive air flow that will continue moving upwardly and be discharged through the open top ends of the conduits  14 , entering the boots and effecting drying action by evaporation created by warm air movement against the adjacent internal surfaces of the boots. The air cooled by evaporation will drop down outside the conduits  14  and exit from below the boot top. Thus a constant drying airflow is produced until either the boots are removed or the valve  31  is turned off. 
     The ducts  26  are also heated by conduction from the collector plenum  32 . The warmed upright ducts, also warm the air along the internal air spaces  56 , thus inducing further upward air flow. Cooler replacement air is naturally drawn into the air spaces  56  through the bottom ends of the conduits  14 , to replace the heated air which moves upwardly through the internal air spaces  56  and into the boots through the top ends of the conduits. The same process occurs in the external air spaces  58  between the heat shields  54  and inner walls of the conduits, only the air within the external spaces  58  will be substantially cooler than the air passing through the internal air spaces  56  and inside the convection air ducts  26 . Still, the air in the external spaces  58  will also raise by convection and pass through the boots to assist in the drying effort. 
     Once the boots are dry, the valve  31  may be turned to an off position, blocking flow of gas to the burner. The flame will thus be extinguished and the dry, warm boots may be removed for use. 
     In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.