1. Field of the Invention
The present invention relates to a siphon coffee maker or like beverage making device, wherein a lower container containing water is heated to obtain hot water, which is fed, by the force of vapor pressure, to an upper container containing material such as coffee powder, thereby extracting coffee or other beverage.
2. Description of the Prior Art
One of conventional siphon coffee makers of the above-described type is shown in FIG. 7. A flask-shaped lower container 3 is supported by a support arm 2 and disposed on a heater 1. An upper container 4 is disposed over the lower container 3 and has an open bottom to which a water feed tube 5 is secured. The water feed tube 5 is inserted into the lower container 3 so as to air-tightly communicate between the containers 3 and 4. The upper open end of the water feed tube 5 is covered by a filter 6 provided on the bottom of the upper container 4.
When coffee is extracted with the above-described siphon coffee maker, a desired amount of water and coffee powder is supplied into the lower and upper containers 3 and 4, respectively. The heater 1 is thereafter energized to apply heat to the lower container 3 containing water. When the water is boiled, the aerial pressure in the lower container 3 is increased, whereby the hot water is fed to the upper container 4 through the water feed tube 5 and filter 6. The hot water is mixed with coffee powder in the upper container 4. Thereafter, when the heater 1 is deenergized, the lower container 3 is cooled and the aerial pressure therein is decreased, whereby the hot water mixed with coffee powder in the upper container 4 is filtered by the filter 6 and falls into the lower container 3 through the water feed tube 5. The upper container 4 is then removed from the lower container 3 and coffee obtained in the lower container 3 is poured into a cup or cups.
The heating capacity of the heater 1 is conventionally set at a relatively large value in order to accelerate the making of hot water. When an input power of the heater 1 is set and maintained at the maximum value through a hot water making step to obtain hot water, the heater 1 is led into an over-heating condition as the temperature of water in the lower container 3 reaches the boiling point. Accordingly, the boiling phenomenon in the lower container 3 is rendered too intense at the last stage of the hot water making step. Therefore, when the hot water nearly finishes transferring from the lower container 3 to the upper container 4, the vapor generation is particularly intensified in the lower container 3. The vapor bursts up into the upper container 4 and overstirs the hot water and coffee powder therein. Consequently, coffee extracted becomes cloudy or unnecessary ingredients spoiling the flavor of coffee are extracted from coffee powder.