Stoves and furnaces – Tool having fluid fuel burner – Soldering iron
Patent
1989-02-09
1990-06-12
Dority, Carroll B.
Stoves and furnaces
Tool having fluid fuel burner
Soldering iron
13750525, 137498, 431344, 431 89, 431354, 141349, B23K 302
Patent
active
049323938
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This specification relates chiefly to gas heated tools and the like and particularly but by no means exclusively to portable gas operated tools and appliances such as, for example, soldering irons, glue guns, hair curling tongs and so forth.
The disclosure is particularly concerned with aspects of safety, stability of output, efficiency and ease of operation of the tools.
In GB-A-1524185 there is disclosed a gas-fired soldering iron in which gas is supplied from a cylinder to a jet via a regulating valve which is used to control the rate of flow, the gas issuing from the jet is mixed with air and the gas/air chamber which is enclosed by a gauze, for example.
SUMMARY OF THE INVENTION
It has now been found that improved performance of such apparatus can be achieved by providing not only a variable gas flow but also by providing a variable gas/air ratio in accordance with the rate of flow. This enables the correct gas/air ratio to be used in dependence on operating conditions, for example during ignition, or at a gas flow chosen for a particular operating temperature, or where the apparatus is to be used in windy conditions or the like.
Thus, viewed from one broad aspect there is disclosed herein a gas heated tool comprising a mixture supplying conduit for feeding gas/air mixture to an enclosed combustion chamber having means for allowing the exit of exhaust gas, a jet for introducing pressurised fuel gas into the conduit, control means for adjusting the flow of gas into the conduit to a desired level, and air admission means through which air can be drawn into the COnduit, the air admission means being adjustable so as to vary the air/gas ratio of the mixture supplied to the combustion chamber, wherein the control means for adjusting the flow of gas into the conduit is operative simultaneously to determine the degree of adjustment of the air admission means.
By so arranging the control means, the relationship between the gas flow and the gas/air ratio can be chosen to cope with varying conditions. In general the relationship will be non-linear. For example, an increase in gas flow from zero to maximum may be accompanied initially by no change in the air/gas ratio, followed by a reduction so that there is a richer mixture at maximum flow. There may be specific adjustment positions, such as a less than maximum flow with a richer mixture than for normal maximum output, for use in high wind conditions, and a lower flow rate with an even richer mixture for use in start-up. The versatility of the control means is preferably such that the same rates of flow can be associated with different mixture strengths for use in accordance with the running conditions.
Thus in a gas heated soldering iron, for example, the burner which heats the soldering tip operates on the Bunsen burner principle in which air is mixed with gas at a position spaced from the combustion position but, instead of the gas regulating means and air regulating means being separate and separately operated, they are combined and operated by a single control. Since the gas and air are mixed prior to combustion the flame can burn in a confined space within a head of the tool, such confined space being, for example, 0.35 cc for an iron equivalent to a 60 watt electric iron.
The supply of correct air gas mixures is essential for stability, clean combustion, operation in high winds, temperature adjustment, linear combustion and safety. Pressure regulation is also important.
The iron preferably runs in an over aerated state. Since it cannot be started in this condition the mixture is richened for starting but backed off after starting since as the iron heats up the density of the gas falls. A richer setting is available for high wind or other unstable conditions.
In a preferred arrangement, the air admission means includes a rotatable member which is rotated to adjust the available flow cross-section for air. The rotatable member could be in the form of a cover movable over an aperture, but is preferably provided with one or mo
REFERENCES:
patent: 1281300 (1918-10-01), Cross
patent: 1548447 (1925-08-01), Dice
patent: 1768147 (1930-06-01), Raymond
patent: 3299940 (1967-01-01), Phillips et al.
patent: 3642422 (1972-02-01), Schafer
patent: 3941554 (1976-03-01), Curtis
patent: 4793798 (1988-12-01), Sabin
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