GB2073397A

GB2073397A - Gas fuelled heating appliance

Info

Publication number: GB2073397A
Application number: GB8011515A
Authority: GB
Original assignee: Bullfinch Gas Equipment Ltd
Current assignee: Bullfinch Gas Equipment Ltd
Priority date: 1980-04-08
Filing date: 1980-04-08
Publication date: 1981-10-14
Also published as: GB2073397B

Abstract

A hand-held gas fuelled heating appliance, typically a blowtorch, has a handle assembly 10 and a burner assembly 30, preferably releasably connected so that burner assemblies with burner heads of different sizes can be interchanged. The handle assembly includes a duct 15 for fuel and a piezo-electric or other electric actuator 17 for energising a spark ignition device 34 at or near the rear end of the burner assembly, there being a mixing chamber 35 in said rear end in which the gas fuel is mixed with air to pass along a passage to the burner head. Sustained combustion takes place at the head, ignition being effected by transient combustion in the passage remote from the head which is communicated thereto. <IMAGE>

Description

SPECIFICATION Gas fuelled heating appliance This invention relates to hand-held gas fuelled heating appliances, particularly but not exclusively blowtorches burning a mixture of liquid petroleum gas and air.

The object of the invention is to provide a blowtorch or other appliance which is particularly convenient and adaptable in use, the preferred form of the invention providing a blowtorch having a standard handle incorporating an ignition actuator and which can be speedily coupled to and uncoupled from interchangeable burners of a range of capacities.

According to the invention there is provided a hand-held gas fuelled heating appliance comprising a handle assembly and a burner assembly, the latter including a burner head remote from the connection with the handle assembly and at which sustained combustion of an ignitable fuel mixture takes place in use, a chamber adjacent to said connection in which said mixture is operatively formed, a passage along which the mixture passes to the head, and a spark ignition device acting to provide transient combustion of mixture in said passage substantially upstream of the head which will be communicated through the head to initiate said sustained combustion thereat; and the handle assembly including a duct for gas fuel leading to said burner assembly chamber, and a selectively operable electric actuator operatively providing electrical energy to said spark ignition device.

Conveniently the electric actuator is a pushbutton operated piezo-electric generator.

Conveniently the two assemblies are releasably coupled together, preferably by a single union rigidly coupling the gas fuel duct to a connection on the burner assembly leading to said chamber, and, when so coupled,, an electrical conductor of the burner assembly leading to the ignition device is automatically aligned to receive electrical energy from the electric actuator of the handle assembly.

The handle assembly may incorporate a valve for regulating the fuel supply.

One specific embodiment of the invention is now described in detail with reference to the accompanying drawing being a part-sectional side elevation of a hand held blowtorch for burning a mixture of liquified petroleum gas (e.g. propane or butane) or "natural" gas, and air.

The blow torch comprises two main assemblies, a handle assembly 10 and a burner assembly 30.

Handle assembly 10 comprises a body 1 2 formed from a pair of plastics mouldings shaped to fit the hand and accommodating a screw-down valve 1 3 at the end remote from burner assembly 30 for regulating the gas fuel supply which passes from a nipple 1 4 for receiving a flexible hose through valve 1 3 and along a rigid metal tube 1 5 within the handle assembly to a screw coupling 1 6 which is releasably coupled to and forms a rigid connection with burner assembly 30.

By undoing coupling 1 6 burner assembly 30 can be removed and interchanged with other burner assemblies of different sizes.

Handle assembly 1 2 further comprises a piezo-electric generator 1 7 actuated by a push-button 1 8 positioned conveniently for a user's thumb. One pole of the generator output is connected by an insulated wire 1 9 to a conductor 20 having an exposed end in an end wall of a recess 21 in body 12 adjacent to connection 1 6. The other pole of generator 1 7 is the metal body of the generator itself and is connected electrically to tube 1 5 by a spring metal contact strip 22 within the handle.

Burner assembly 30 is fabricated from metal tubing and comprises a burner head 31 at the end remote from handle assembly 10 and angled with respect to the general longitudinal axis of the latter for convenience in use, carried on a co-axial burner tube 32 whose rearward end defines an ignition chamber 33. A sparioplug 34 having a single central electrode locates in the rearward end of tube 32 and, when assemblies 30 and 10 are coupled together, the outer end of said electrode is in close proximity to the conductor 20 to receive electrical energy from generator 17.

A mixer tube 35 is joined to burner tube 32 at an angle of 30"-45", the junction being between chamber 33 and head 31. The rear end of mixer tube 35 mounts a gas jet 36 which receives the flow of fuel from tube 15, connection 1 6 being provided with seals to form a gas tight joint. Tube 35 includes one or more apertures 37 for admitting air adjacent to jet 36 and is shaped to form a venturi mixirig chamber 38 downstream of jet 36 in which an ignitable fuel/air mixture is formed during use, selectively regulated by valve 1 3.

The construction which enables formation of the gas/air mixture is conventional and will not be described in greater detail.

The burner tube 32 and/or burner head 31 may incorporate formations which provide flame retention at the burner head and/or facilitate reliable transfer of ignition to initiate the flame at the head, for example as described in our co-pending patent application No. of even date herewith.

The handle assembly 10, as above described, will accommodate a range of sizes of head assembly 30, interchange being speedily effected by simply undoing connection 1 6. As the ignition device is positioned to the rear of head assembly 30 no physical electrical connections have to be provided and it is is not necessary to arrange for electrical leads or conductors extending to the burner head 31.

In this particular example five interchangeable head sizes are provided to give heat rates of from 0.32 kwto 4.5 kw.

Once the desired head assembly has been mounted the gas fuel supply is turned on so creating a combustible gas/air mixture which quickly fills tubes 35 and 32 including ignition chamber 33. Generator 1 7 is operated by pressure on push-button 1 8 and the resulting charge of electrical energy jumps the small gap to the electrode of sparkplug 34, and arcs from the inner electrode tip to the metal body of head assembly 30, so igniting the mixture in chamber 33, the return side of the circuit being through metal to metal connection 1 6 and contact strip 22. Ignition of mixture in chamber 33 travels down tube 32 through burner head 31 to initiate sustained combustion at the head and the flame is then controlled in the usual way by operation of valve 13.

It will be noted that sparkplug 34 is positioned a substantial distance from the burner head so that it is not subjected to direct flame and consequent overheating while the blowtorch is operating and the arrangement described provides a particularly compact and convenient blowtorch structure having neat appearance with particularly convenient operation and control.

Head assembly 30 includes a rest and/or hook 39 for hanging or placing the torch safely when not in use.

Claims

1. A hand-held gas fuelled heating appliance comprising a handle assembly and a burner assembly, the latter including a burner head remote from the connection with the handle assembly and at which sustained combustion of an ignitable fuel mixture takes place in use, a chamber adjacent to said connection in which said mixture is operatively formed, a passage along which the mixture passes to the head, and a spark ignition device acting to provide transient combustion of mixture in said passage substantially upstream of the head which will be communi cated through the head to initiate said sustained combustion thereat; and the handle assembly including a duct for gas fuel leading to said burner assembly chamber, and a selectively operable electric actuator operatively providing electrical energy to said spark ignition device.

2. An appliance as in Claim 1 wherein the electric actuator is a piezo-electric generator.

3. An appliance as in Claim 1 or 2 wherein the electric actuator is push-button operated.

4. An appliance as in Claim 1, 2 or 3 wherein the two assemblies are releasably coupled together.

5. An appliance as in Claim 4 wherein said assemblies are coupled by a single union rigidly coupling the gas fuel duct to a connection of the burner assembly leading to the chamber.

6. An appliance as in Claim 4 or 5 wherein the burner assembly includes an electrical conductor leading to the ignition device, which conductor is automatically aligned to receive electrical energy from the electric actuator of the handle assembly when said assembles are coupled together.

7. An appliance as in any one preceding claim wherein the handle assembly further includes a valve for regulating the fuel supply.

8. An appliance as in any one of Claims 4 to 7 including a plurality of burner assemblies each having a burner head of a different size for selective coupling to a single handle assembly.

9. A hand-held gas fuelled blowtorch substantially as hereinbefore described with reference to and as shown in the accompanying drawing.