1. Field of the Invention
The present invention relates to a domestic catalytic combustion device using catalytic combustion heat as the heat source.
2. Description of Related Art
Heretofore catalytic combustion devices wherein a fuel, which is a gas at room temperature (hereinafter referred to as "liquefied fuel"), such as hydrogen, methane, propane or butane is burnt on surfaces of a catalyst consisting of a noble metal such as platinum or palladium carried on a support or carrier made of glass fibers, porous metal or ceramics. Such catalytic combustion devices are used in domestic appliances such as radiant heaters or stoves fired with a liquefied petroleum gas (LPG) or town gas, soft soldering irons or hair curlers fired with an LPG, or body warmers fired with benzine.
According to the known devices, it has been customary practice to adjust the rate of supply of fuel by means of a pressure regulator and a nozzle associated therewith, thereby adjusting the amount of combustion and the heating temperature. With this arrangement, the adjustment of the amount of combustion in response to the temperature of a combustion chamber or an object to be heated is difficult to achieve.
The catalytic combustion burner is required to have a small thermal capacity for ignitability. Further, the temperature of the catalyst well depends on the change in the rate of supply of gas. Therefore, it is required that the gas supply to the catalytic combustion burner is controlled in response to the temperature of catalyst. Because of its greater thermal capacity, the heating object cools substantially slower than the catalyst during which time the temperature of the catalyst is lowered below the combustible temperature. The catalyst cannot be ignited again and hence a continuous combustion cannot be achieved. On the other hand, at the ignition and temperature glow stages, the catalyst becomes hot well before the heating element is heated and sometimes it is heated at an undue elevated temperature which would have a negative influence on the service time of the catalyst. In order to overcome the foregoing drawbacks, it is necessary to detect a temperature at a point adjacent to the catalyst.
There have been known hair curlers which comprise a bimetal or an expandable liquid thermostatic element disposed in a heating chamber containing a catalytic combustion burner for detecting temperature and for controlling the rate of gas flow in response to the detected temperature. The known hair curler has a drawback in that both the burner and the thermostatic element are disposed in a curling pipe and hence reduction in diameter of the curling pipe is difficult to achieve.
Gas-fired ovens, gas-fired grills or gas-fired water heaters with a flame combustion burner without using a catalyst are known in which a bimetal or an expandable liquid thermostatic element is disposed in a combustion chamber or heating object for detecting the temperature to thereby adjusting the amount of combustion gas. With this arrangement, the thermostatic element is disposed in the combustion chamber through which the waste gas flows, so that the thermostatic element is susceptible to corrosion. A further disadvantage is that a cooking material or other substance is likely to adhere to the surface of the thermostatic element to thereby alter the set temperature.