PORTABLE ELECTRIC AIR-HEATING GUN AND OVEN

• US 3,610,881 A
• Filed: 07/29/1968
• Issued: 10/05/1971
• Est. Priority Date: 07/29/1968
• Status: Expired due to Term

• Current Assignee: Trigg Stewart
• Original Assignee: Trigg Stewart
• Inventors: Stewart, Trigg
• Primary Examiner(s): Bartis, A.
• Application Number:
  US04/748,317
• Time in Patent Office: 1,163 Days
• Field of Search: 219/363,364,365,366-377,379-381,400 34/43,48,237,96-101,243
• US Class Current: 392/384
• CPC Class Codes: F24H 3/0423 hand-held air guns
• CPC Class Codes: F27D 11/02 Ohmic resistance heating
• CPC Class Codes: H05B 3/0019 Circuit arrangements

Abstract

A portable hand-carried air gun having a fan that forces volumes of air through a casing. The casing has heating coils therein for heating the air passing therethrough. A plate in the discharge end of the casing blocks the direct flow of air out of the discharge end and forces the air to move through an annular space between the outer edge of the plate and the casing. The plate and casing thus forms a chamber between the plate and the heating coils for mixing the airflow after passing through the heating coils and prior to passing out through the annular spaced. A temperature-sensitive element responsive to the temperature of the air in the chamber adjusts the current to the heating coils to hold the air in the chamber to a set temperature. An oven container for receiving the discharge end of the portable air gun provides a quick and easily heated oven.

Claims

1. A portable air gun comprising, a hollow elongated casing and air inlet and an air outlet, air source means for supplying volumes of air under pressure to said inlet for flow through said casing and out said outlet, electrical heating coils positioned around the inner periphery of said casing for heating the air flow therethrough, electrical circuit means for supplying electrical power for said electrical heating coils, a plate positioned in the center of said outlet and having an area smaller than the area of the outlet for directing airflow through the space between the outer edge of said plate and the inner surface of said casing at said outlet, said electrical circuit means includes power control means for controlling the electrical power to said heating coils, thereby controlling the temperature of the air flowing out , which power control means has temperature-sensitive means positioned in said casing adjacent said space and electrically connected to said electrical circuit means and electrically responsive to the temperature of said airflow, an electrically insulative plate positioned longitudinally in said casing, and electrically insulative tube positioned longitudinally on each side of said plate, said heating coils being spiralled around said electrically insulative plate and said tubes, said temperature-sensitive means comprising a thermistor circuit wires for electrically connecting said thermistor in said electrical circuit means which wires pass through said electrically insulative tube, said air source means comprises a centrifugal fan unit having an air intake and an air discharge that is connected to said air inlet, said electrical circuit means includes a plurality of electrical components, some of which electrical components have electrical parameters that are mechanically adjustable, plate Means for supporting a substantial number of said electrical components in said air intake, whereby said components are cooled by the passage of the intake air, a plurality of said components in said electrical circuit means being connected to metallic plates projecting into said air inlet t for dissipation of heat from said components to the airflow through said metallic plates, a cover positioned over said plates means and said electrical circuit means having air passage openings for passing airflow through said inlet, and a plurality of said components of said electrical circuit being reachable for selective adjustment through said air passage openings.

2. A portable air gun comprising, a hollow elongated casing having an air inlet and an air outlet, air source means for supplying volumes of air under pressure to said inlet that will flow through said casing and out said outlet, electrical heating coil positioned around the inner periphery of said casing for heating the airflow therethrough, electrical circuit means for supplying electrical power to said electrical heating coil, a flat plate positioned in the center of aid outlet and having an area smaller than the area of the outlet for directing airflow through the space between the outer edge of said plate and the inner surface of said casing at said outlet, said plate being spaced forwardly of said heating coils and forming a chamber therebetween and having a blocking surface on the side adjacent said coils for blocking airflow and causing mixing of the airflow in said chamber after passage of said airflow through said coil and prior to passage through said space, a temperature-sensitive element having electrical parameters that change with temperature being positioned in said chamber adjacent said space, and said electrical circuit means including power control means electrically connected to said temperature sensitive element and being responsive to changes in said electrical parameters for controlling the electrical power to said heating coils, thereby controlling the temperature of the air flowing out said outlet.

3. A portable air gun as claimed in claim 2 in which, said air air source means comprising a centrifugal fan unit having an air intake and an air discharge that is connected to said air inlet, said electrical circuit means includes a plurality of electrical components that are subject to deterioration from heat, and plate means for supporting said plurality of electrical components in said air intake whereby said components are cooled by intake air and are separated from said heating coil by said plate means.

4. A portable air gun as claimed in claim 3 including, a cover for being positioned over said plate means and said components of said electrical circuit means, selective ones of said electrical components have adjustable means for mechanically adjusting the electrical parameters of said selective ones of said electrical components, and said cover having openings therethrough for engaging said adjustment means.

5. A portable air gun as claimed in claim 3 in which, said components in said electrical circuit means being connected to metallic plates projecting into said inlet for dissipation of heat from said components through said metallic plates projecting into said inlet for dissipation of heat from gun components through said metallic plates to the air flow.

6. A portable air gun as claimed in claim 2 including, an oven compartment having an opening in the side near the bottom for receiving the outlet end of said casing and having an opening in the top for passing heated air from said outlet end through said oven compartment, a second temperature-sensitive element having electrical parameters that change with temperature which element is placed in said oven volume, and switch means for switching said second temperature-sensitive element means into said electrical circuit means in Place of the temperature-sensitive element.

7. A portable air gun as claimed in claim 2 in which, said plate is supported in said openings by a screen, and a tube being concentrically mounted on the outer surface of said casting and spaced therefrom providing an air space therebetween.

8. A portable air gun as claimed in claim 2 including, an electrically insulative plate positioned in said casing, and electrically insulative tube positioned longitudinally on each side of this plate, said heating coil being spiralled around said electrically insulative plate and tubes, said temperature sensitive element comprising an electrical temperature sensitive probe, and circuit wires between said probe and said electrical circuit means for passing through said electrically insulative tube.

9. A portable air gun as claimed in claim 8 in which, said temperature sensitive probe comprises a thermistor, and said power control means including means responsive to the temperature condition of said thermistor for controlling the magnitude of current flow through said heating coils.