| 摘要 |
PROBLEM TO BE SOLVED: To easily adjust a feed water amount and to obtain stable feed water characteristics by controlling driving conditions such as the operation rate and driving timing of DC pumps and suppressing the pulsation of drinking water or hot water fed toward an extractor. SOLUTION: DC electromagnetic pumps 5A and 5B are connected in parallel to a piping 3A supplying drinking water from a cistern 2 to a boiler 4. When coffee beverage is extracted, the feed water amounts of the pumps 5A and 5B need to be increased as extraction resistance increases so as to a specific amount of coffee beverage within a necessary time. For the purpose, the operation rate is set to 30% in the starting 2 seconds from the start of the extraction, 50 to 70% in following 3 seconds, and 80 to 100% in the remaining 4 seconds, thereby performing proper extracting operation. Further, the pumps 5A and 5B are driven with a prescribed voltage and the pulsation becomes stable to prevent a flowmeter which detects the pressure in the piping from decreasing in detection sensitivity, thereby grasping an accurate flow rate. |
