Stoves and furnaces – Heaters – Chemical
Patent
1993-12-06
1995-07-04
Yeung, James C.
Stoves and furnaces
Heaters
Chemical
126262, F24J 100
Patent
active
054291151
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a heater unit for use in a self-heating container. In particular it relates to parts for a solid fuel heater unit with a manually operable igniter for automatically igniting the solid fuel. The unit is particularly suitable for use in disposable self-heating food containers, but is not limited to this.
2. Description of the Related Art
A food container with a built-in heater of this type is described in published International patent application WO-A-83/00425.
The heater includes a top heat spreading layer, and a layer of exothermic material having internal walls and arranged on a heat insulating non-combustible layer. Under the non-combustible layer, a slidable striker is positioned in contact with a friction responsive element. A primer material is supported in the non-combustible layer between the friction responsive element and the exothermic material for initiating the exothermic reaction once the primer has been ignited.
Such an arrangement is quite complicated and involves a large number of different parts. In at least some of the embodiments described in WO-A-83/00425, the parts are "stacked" loosely together in the base of the food container, and the design relies on at least a portion of the container itself to hold the heater parts together in the correct position.
SUMMARY OF THE INVENTION
In a first aspect, the present invention provides a heater unit for installation in a disposable self-heating container, the heater unit comprising solid fuel means, slidably activated friction-responsive igniter means, and a single piece carrier member, the carrier member including first means for securing the solid fuel means to the carrier member, second means for operatively securing the igniter means to the carrier member in use to enable the igniter means to ignite the solid fuel means, and third means securable to a said disposable container to facilitate installation of the heater unit.
Such a heater unit uses fewer parts than the prior art, and can be made simple to assemble. The unit is self-contained and does not rely on other parts of the disposable container to hold the solid fuel means and the igniter means in position. The unit can be fully assembled before installation in the container.
The carrier member should preferably be made of a non-combustible material which is able to withstand the heat produced once the burner has been ignited. A suitable material is, for example, tinplate.
Preferably, the first means of the carrier member comprise one or more fingers for fitting over at least a portion of the solid fuel means. The fingers may be hook-shaped. The solid fuel means may have a hole therethrough through which the first means fingers pass. In the preferred embodiment, the solid fuel means comprises an annular solid fuel tablet. The solid fuel may, for example, comprise hexamethylene tetramine, or a mixture of hexamethylene tetramine, silica, sulphur, potassium and calcium.
In the preferred embodiment, the solid fuel burns for approximately 4 to 6 minutes after it has been ignited. It produces heat to heat the container's contents to about 100.degree. C.
Preferably, the igniter means comprises an igniter strip and friction-responsive ignition material, and the second means of the carrier comprises a sleeve in which the igniter strip is slidably retained in contact with the friction-responsive ignition material.
The ignition material may be mounted adjacent to the opposite face of the igniter strip to the solid fuel means. In use, the igniter strip is slidably extracted from the sleeve to cause the ignition to flare, and ignite the solid fuel means.
The ignition material may, for example, comprise a mixture of potassium chlorate, sulphur, gelatine, glass powder, potassium dichromate and carbon black. The material may also include a filler. The igniter strip may include a rough coating for producing frictional heat from contact with the ignition material when the strip is pulled. The coating may compris
REFERENCES:
patent: 4424798 (1984-01-01), Volk
patent: 4819612 (1989-04-01), Okamoto et al.
patent: 4899721 (1990-02-01), Tsay
patent: 5020509 (1991-06-01), Suzuki et al.
patent: 5048506 (1991-09-01), Hayashi
patent: 5220908 (1993-06-01), Iizuna et al.
Goon Ngan T.
Tan Phang K.
Effort Holdings Pet, Ltd.
Yeung James C.
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