Abstract:
A gas hot air gun includes a main body, an ignition device, a switch set and a safety switch. The main body includes a blower, a nozzle, a barrel and a handle. A heating chamber and a mixing chamber are on the inner front of the barrel. A gas can is inside the handle. One end of the nozzle is connected to the gas can. The switch set includes a power switch, with the safety switch closing power of the battery set or gas flow under some pre-set conditions. Users press the power switch and have gas spray out from the nozzle into the heating chamber to generate heat. The blower sends hot air in the heating chamber out of the main body. A metal slice regulating the direction of air and a catalyst for avoiding flame extending out of the nozzle area are inside the heating chamber.

Description:
CROSS REFERENCE  
       [0001]     The present application is a continuation of U.S. application Ser. No. 10/899,699 filed on Jul. 26, 2004. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     I. Field of the Invention  
         [0003]     This invention relates generally to a hot air gun and, more specifically, to a gas hot air gun that offers smaller physical size for users to carry around, complete burn of gas to reduce carbon monoxide and faster cooling down the whole set after application to prevent users from danger of burning, with a safety switch stopping power or gas flow under some pre-set conditions for safety purposes.  
         [0004]     II. Description of the Prior Art  
         [0005]     Heretofore, it is known that the “Internal structure of a hot air gun” of Taiwan Patent No. 286505 comprises a main body  1 , a handle  2  and a power supply  3 . The main body  1  connects to the handle  2  with a hinge  11 . The main body further comprises a motor  14 , a fan  15  on the motor axis  141  of the motor  14 , and a fan blade  16  on the front of the fan  15 . A burning chamber  161  is beneath the fan blade  16 . An ignition tube  17  interlinks to the burning chamber  161 . A temperature control switch  18  and a control rod  19  are installed inside the ignition tube  17 . A power supply  3  and gas can are inside the handle  2 . A flow control knob  23  is on top of the handle  2 . A flame nozzle  24  is on the front of the flow control knob  23 . The flame nozzle  24  is ignited inside the burning chamber  161  beneath the fan blade  16 . A press button  25  and a switch  26  are installed on the handle to ignite the gas and turn the motor  14  on.  
         [0006]     Many drawbacks exist on the known gas hot air gun. The flame burns the gas in the burning chamber  161  beneath the fan blade  16  after the gas is ignited, and hot air is blown out by the fan blade  16  of the fan  15 . However, the flame inside the burning chamber  161  is blown out easily and burn users, and thus is not very safe. The temperature control switch  18  reduces the gas quantity after the temperature is high, and when the temperature is low, the gas quantity is increased to have a larger flame. However, such design introduces incomplete burning of gas so that the air injected might contain large quantity of carbon monoxide. Thus, it is very dangerous for users to apply the equipment in a sealed environment.  
       SUMMARY OF THE INVENTION  
       [0007]     It is therefore a primary objective of the invention to provide a gas hot air gun that improves known hot air guns.  
         [0008]     In order to achieve the objective set forth, a gas hot air gun in accordance with the present invention comprises a main body, an ignition device, a switch set and a safety switch. The main body comprises a blower and a nozzle. The main body has a barrel and a handle. A heating chamber and a mixing chamber are on the inner front of the barrel. A battery set and a gas can are inside the handle. One end of the nozzle is connected to the gas can. The switch set comprises a power switch and an ignition switch. The safety switch connects to the switch set electrically. The safety switch closes power of the battery set or gas flow of the gas can under some pre-set conditions. Users press the power switch and have gas spray out from the nozzle into the heating chamber to generate heat, with the blower sending hot air in the heating chamber out of the main body. A metal slice regulating the direction of air and a catalyst for avoiding flame extending out of the nozzle area are inside the heating chamber. The present invention is small in size and easy for users to carry. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     The accomplishment of the above-mentioned objective of the present invention will become apparent from the following description and its accompanying drawings which disclose an illustrative embodiment of the present invention and which are as follows:  
         [0010]      FIG. 1  is a perspective view of the present invention;  
         [0011]      FIG. 2  is an exploded perspective view of the present invention;  
         [0012]      FIG. 3  is a cross-sectional view of the present invention;  
         [0013]      FIG. 4  is a cross-sectional view of the present invention;  
         [0014]      FIG. 5  is a cross-sectional view of the present invention; and  
         [0015]      FIG. 6  is a cross-sectional view of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0016]     Referring to  FIG. 1  to  FIG. 6 , the present invention comprises a main body  10 , an air blower  20 , an ignition device  30 , a nozzle  40 , a switch set  50  and a safety switch  60 . The main body  10  consists of a barrel  111  and a handle  12 . A heating chamber  111  is inside the barrel  11 . A gas can  122  is inside the handle  12 . Users can press the switch set  50  to start the safety switch  60  and have the gas of the gas can  122  spray out from the nozzle  40  into the heating chamber  111 . The ignition device  30  ignites the gas inside the heating chamber  111  to generate a heat source. The air blower  20  blows the hot air inside the heating chamber  111  externally to the main body  10 .  
         [0017]     The main body  10  comprises an intake  13  and a exhalation hole  14 . The heating chamber  111  and a mixing chamber  112  are on the inner front of the barrel  11 . A daisy shaped metal slice  113  and a catalyst  114  are inside the heating chamber  111 . The metal slice  113  is installed inside the heating chamber  111  near the front side of the barrel  11 . The catalyst  114  is installed near the end of the barrel  11 . A burning chamber  115  is inside the metal slice  113 . The mixing chamber  112  is installed in the barrel  11  opposite to the location of the heating chamber  111 . A shrink  116  near the metal slice  113  is formed on one end of the mixing chamber  112 . The shrink  116  is interlinked to the burning chamber  115  of the metal slice  113 . Several air inhalation holes  117  are around the mixing chamber  112 . Passages  118  are between the metal slice  113  and the barrel  11 . A tube shaped metal net  119  controlling the mixing air flow is installed between the burning chamber  115  of the metal slice  113  and the shrink  116  of the mixing chamber  112 . A thicker metal net  120  with smaller net holes near the exhalation hole  14  is on one side of the metal net  119 .  
         [0018]     The handle  12  is connected to and beneath the barrel  11 . A first container  123  and a second container  124  are inside the handle  12 . A battery set  121  and the gas can  122  are inside the first and the second containers  123 ,  124 , respectively. The gas can  122  contains burnable fluid, usually liquid gas. A movable cover  125  is on the bottom of the handle  12  to cover the first and the second container  123 ,  124 . The intake  13  is installed on the end of the barrel  11  for air to flow into the barrel  11 . Several protective grids  131  are on the intake  13  to prevent users from inserting their fingers in. The exhalation hole  14  is on the front of the barrel  11  to expel air from the barrel  11 . A holder  15  is installed on the front of the barrel  11  for faster heating effect.  
         [0019]     The air blower  20  is installed internally on the end of the barrel  11  to draw air from the intake  13  into the barrel  11 . The blower  20  comprises a motor  21 , such as a DC motor in this application, and a fan blade  22 . The motor  21  is located near one side of the exhalation hole  14 . The fan blade  22  is installed on the motor  21  and near one side of the intake  13  to be driven by the motor  21 . A temperature sensor  23  is installed around the barrel  11  near the heating chamber  111  and the exhalation hole  14 . The temperature sensor  23  controls the motor  20 . Specifically, after the end of the application and when the temperature of the heating chamber  111  is below a certain temperature, the temperature sensor  23  stops the motor  21  from turning.  
         [0020]     The ignition device  30  is installed inside the metal slice  113  of the heating chamber  111  to ignite the mixed gas in the heating chamber  111 . The ignition device  30  is installed inside the burning chamber  115  of the metal slice  113  in this application.  
         [0021]     The nozzle  40  is installed inside the barrel  11  of the main body  10  and located between the air blower  20  and the mixing chamber  112 . One end of the nozzle  40  is connected to the gas can  122 .  
         [0022]     The switch set  50  is installed inside the handle  12  of the main body  10  near the barrel  11 . The switch set  50  comprises a power switch  51 , a control rod  52 , an ignition switch  53  and a regulation valve  54 . The control rod  52  controls opening and closing the gas can  122 . The ignition switch  53  connects to the ignition device  30  with electrical wires. The regulation valve  54  is installed on the gas can  122  to control the gas flow amount of the gas can  122 .  
         [0023]     The safety switch  60  is connected to the power switch  51 , the motor  21 , the temperature sensor  23  of the air blower  20 , the battery set  121  on the handle  12  and the control rod  52  of the switch set  50 , with all these components being controlled by the safety switch  60  to turn on and off.  
         [0024]     Referring to  FIG. 4 , when the power switch  51  is pressed on, the safety switch  60  is activated. The safety switch  60  turns on the control rod  52  to open the gas can  122 , and the gas sprays out from the nozzle  40 . At the same time, the safety switch  60  activates the blower  20  to blow air from the intake  13  into the mixing chamber  112  to mix the gas and the air blown in. When the mixed gas passes through the shrink  116  and due to the shrinking diameter of the shrink  116 , the mixed gas is compressed so that the mixed air sprays out the shrink  116  at a faster speed. The high speed injected mixed air entering the burning chamber  115  of the metal slice  113  flows to the tube shaped metal net  119  that guides the flow direction of the mixed gas (referring to  FIG. 5 ) which is blocked by the thicker metal net  120  on the front of the tube shaped metal net  119  and the tube shaped metal net  119  itself. Since the net holes of the thicker metal net  120  is smaller, the mixed gas is blocked effectively to have most of the mixed gas sprayed out in all directions. When the ignition switch  53  is pressed, the ignition device  30  ignites the mixed gas and generates the flame forming the first burn. The flame expands several tongues of flames from the burning chamber  115  to surround the metal slice  113  and have the temperature of the metal slice  113  rise gradually. Due to the better heat exchange rate of the metal slice  113  and when the air flow sent by the blower  20  passes through the passages  118  of the metal slice  113 , air flow can bring the heat on the metal slice  113  to generate hot air. When the hot air passes through the catalyst  114 , the catalyst  114  burns the small quantity left-over gas to reduce the quantity of carbon monoxide (CO) and that forms the second burning. After two forms of burning, the air temperature is higher, and the air is safer as the catalyst  114  avoids the burning flame in the metal slice  113  from coming out of the exhalation hole  14 .  
         [0025]     The mixed gas needs to have a good ratio of fresh air and gas to be properly burnt. When oxygen contained is too low in the mixed gas, the inhalation holes  117  around the burning chamber  115  offer fresh air. The diameter of the shrink  116  of the mixing chamber  112  shrinks gradually so that fresh air sucked in is mixed with gas and enters the burning chamber  115  to be burnt stably. The quantity of gas can also be controlled by the regulation valve  54 . Since the metal slice  113  inside the heating chamber  111  has very good heat conductivity, the temperature of the metal slice  113  is lifted rapidly after the ignition inside the burning chamber  115 . If the gas in the heating chamber  111  is not burnt properly, the toxic carbon monoxide is generated and is harmful to human body. In order to achieve complete burning, the catalyst  114  can achieve such purpose. Specifically, the catalyst  114  reacts with the burning gas and generates non-toxic carbon dioxide. The catalyst  114  can also prevent the flame from coming out of the exhalation hole  14 .  
         [0026]     When the following situations happen, the safety switch  60  elaborates the proper function. When power switch  51  is on without flame or gas burning stops, the temperature sensor  23  installed on the barrel  11  near the heating chamber  111  detects the temperature did not reach the expected temperature. Thus, the safety switch  60  stops all the signals to make the motor  21  stop, and the control rod  52  breaks away to stop the gas. When the temperature sensor  23  detects abnormally high temperature, the safety switch  60  has the control rod  52  stop the gas and have the motor  21  turn on to blow air until the temperature drops. When temperature sensor  23  detects the temperature remains high after the power switch  51  is off, the safety switch  60  has the nozzle  40  stop spraying gas and turns on the blower  20 . The blower  20  keeps blowing fresh air to cool the temperature of the heating chamber  111 , and the metal slice  113  absorbs the cold fresh air to lower the temperature of the heating chamber  111  due to its good heat conductivity. When the temperature sensor  23  detects the temperature of the heating chamber  111  reached a lower temperature, the blower  20  is turned off. Such design makes the present invention easier to carry without the danger of burning.  
         [0027]     Referring to  FIG. 6 , when the safety switch  60  detects the battery set  121  in low battery condition or gas can  122  has insufficient gas to introduce the burning temperature drop, the safety switch  60  blocks all the signals to stop all operations. A new battery set  121  or gas can  122  can be replaced. Replacement is very convenient as users only need to lift the movable cover  125  and take the battery set  121  or gas can  122  out from the first or the second container  123 ,  124 , respectively, and do the replacement. The gas can  122  can be the re-fill type can. The present invention applies gas to generate high temperature to avoid the troubles of a power cord and to reduce space. Users can carry the present invention around very conveniently.  
         [0028]     While a preferred embodiment of the invention has been shown and described in detail, it will be readily understood and appreciated that numerous omissions, changes and additions may be made without departing from the spirit and scope of the invention.