Combustion – Process of combustion or burner operation – Starting or shutdown procedure
Reexamination Certificate
1998-09-29
2001-06-12
Lazarus, Ira S. (Department: 3743)
Combustion
Process of combustion or burner operation
Starting or shutdown procedure
C431S072000, C431S128000, C431S264000, C431S268000, C431S350000, C431S353000, C126S413000
Reexamination Certificate
active
06244853
ABSTRACT:
The present invention relates to a gas burner of the type in which fuel gas is converted to heat by a catalytic reaction with a gas catalytic combustion element. In particular, the invention relates to a gas burner of the type which is suitable for but is not limited to use in a soldering iron, a glue gun, a clothes pressing iron, a hair curling tongs, a heated hair curler, a hot gas blower for blowing a hot stream of gases, for use, in for example, shrinking an insulating sleeve of plastics material onto electrical connectors, and the like. The invention also relates to a gas powered heating device, and to a method for igniting a gas catalytic combustion element of a gas burner.
Gas powered heating devices, for example, a gas powered soldering iron, a glue gun, a clothes pressing iron, a curling tongs, a heated hair curler, and the like, as well as a hot gas blower are known, and in general, comprise a gas burner which comprises a combustion chamber within which a gas catalytic combustion element is located. A fuel gas/air mixture is delivered into the combustion chamber to pass over, along and/or through the catalytic combustion element so that the fuel gas/air mixture is converted to heat by a catalytic reaction in the catalytic element. Such gas catalytic combustion elements will be well known to those skilled in the art. However, one disadvantage of such gas burners is that initially in order to initiate the catalytic reaction in the catalytic combustion element, the catalytic element must be raised to its ignition temperature. This, in general, requires burning the fuel gas/air mixture in a flame adjacent the catalytic element so that the flame plays on the catalytic element, thus raising the temperature of the catalytic element to its ignition temperature. However, in order that the catalytic combustion element commences to convert the fuel gas/air mixture to heat by the catalytic reaction, the flame must be extinguished so that the fuel gas/air mixture is then played directly onto the catalytic element.
In such devices, in general, a gas jet device is located upstream of the catalytic combustion element relative to the flow of fuel gas/air mixture, and a spark ignition mechanism, typically, ignition electrodes are provided for igniting the fuel gas/air mixture from the jet device to burn in a flame upstream of the catalytic element, so that the flame plays on the catalytic element. The flame raises the catalytic element to its ignition temperature. A piezo electric igniter is typically provided for applying an appropriate voltage to the ignition electrodes for igniting the fuel gas/air mixture.
Various mechanisms are provided for extinguishing the flame after the catalytic element has been raised to its ignition temperature. One such mechanism requires closing an air intake into an area where the fuel gas/air mixture is being burnt in a flame for starving the flame of oxygen, and thus extinguishing the flame. Another mechanism requires closing an air intake through which air is drawn for mixing with the fuel gas for forming the fuel gas/air mixture so that only fuel gas is delivered to the jet, which thus extinguishes the flame.
An alternative mechanism for extinguishing the flame is disclosed in PCT Specification No. WO 95/02788. This PCT Specification discloses a gas powered soldering iron in which a fuel gas/air mixture is converted to heat by a catalytic reaction with a catalytic combustion element which is located in a combustion chamber of the soldering iron. The combustion chamber is located adjacent the soldering tip so that heat generated in the combustion chamber is conducted to the soldering tip. The temperature of the catalytic combustion element is initially raised to its ignition temperature by burning the fuel gas/air mixture in a flame upstream of the catalytic combustion element, and the flame is played on the catalytic combustion element. The flame is extinguished by means of a mechanism which interrupts the flow of fuel gas to a jet from which the fuel gas/air mixture is burnt in the flame. The interruption of gas is for a momentary period only, however, it is sufficient for the purpose of extinguishing the flame.
Such soldering irons and other gas powered heating devices which comprise an ignition mechanism which requires burning a fuel gas/air mixture in a flame for raising the temperature of the catalytic combustion element to its ignition temperature suffer from a number of disadvantages. In such devices where a mechanism for extinguishing the flame is to be operated by the user of the device, in general, the user must determine when the flame should be extinguished, in other words, when the catalytic element has reached its ignition temperature. In the event of such gas powered heating devices comprising a control switch or switches for igniting the fuel gas/air mixture to burn in the flame and for extinguishing the flame, it is important that the switch or switches be timed so that the flame is not extinguished prematurely, in other words, is not extinguished prior to the catalytic element reaching its ignition temperature. This, is not always possible to achieve, and in many instances, many attempts are required in order to operate such heating devices to raise the temperature of the catalytic element to its ignition temperature. This needless to say is undesirable.
Additionally, in devices which comprise one or more control switches for operating the flow of fuel gas, the ignition mechanism, and a mechanism for extinguishing the flame, in general, a number of operations must be carried out by the operator for igniting the fuel gas/air mixture to burn in the flame, and then for interrupting the flow of fuel gas, air or oxygen to extinguish the flame. This likewise is undesirable and may require that many attempts be made in order to raise the temperature of the catalytic element to its ignition temperature.
In typical gas powered heating devices, a switch may be located in the handle, which must be moved to a number of different positions for operating the flow of fuel gas and for raising the temperature of the catalytic element to is ignition temperature. For example, firstly, the switch is moved to a first position for switching on the fuel gas supply to the catalytic combustion element. The switch is then moved to a second position for operating the ignition mechanism for igniting the fuel gas to burn in the flame. The switch is then moved to a third position for interrupting the flow of fuel gas, air or oxygen for extinguishing the flame, and then, to a fourth position for providing a continuous supply of fuel gas to the catalytic element. This, requires considerable skill and dexterity on behalf of an operator, and furthermore, as mentioned above unless the timing of the switch is such to ensure that the flame is not extinguished prior to the catalytic element reaching its ignition temperature, many attempts may be necessary in order to raise the catalytic element to its ignition temperature. Indeed, in many cases, a number of switches are required, and it is necessary for the operator to operate the switches in a particular sequence, and also, to a particular timing schedule. This, is unsatisfactory.
Another arrangement for igniting a catalytic element is of the type which is typically used in a heated hair curling tongs or brush. In such an arrangement, the catalytic element is raised to its ignition temperature by being subjected to a momentary flame which is caused by exploding fuel gas adjacent the catalytic element, typically in a chamber formed within a hair receiving barrel of the curling tongs within which the catalytic element is located. However, because the momentary flame is not sustainable, it is only capable of providing a limited quantity of heat energy, and therefore a low thermal mass catalytic element is required. The low thermal mass catalytic element may be provided on its own and would have sufficient heat output capacity for heating the hair curling tongs, or alternatively, the low thermal mass catalytic element ma
Oglesby Alfred P
Oglesby John P
Cocks Josiah C.
Lazarus Ira S.
Oglesby & Butler Research & Development Limited
Sughrue Mion Zinn Macpeak & Seas, PLLC
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