| 摘要 |
PROBLEM TO BE SOLVED: To make hard to receive the affection of a variety in the efficiencies of each pumps, a temperature change, noises as well as the current consumption of a controlling circuit and permit the accurate detection of an output flow rate generated by the pumps. SOLUTION: A water circulating device is provided with a pump 1, circulating water in a water tank, a motor 2, a driver 3 for changing the rotating number of the motor 2 in proportional to the duty ratio of a pulse, a pulse width modulating circuit 5 for regulating the duty ratio of the pulse to obtain a predetermined number of rotation of the motor 2, a measuring means 6 for measuring the duty ratio of the pulse, a memory 7 into which a characteristic parameter 8 including a relation between the duty ratio and the flow rate is written, and a microcomputer 9 for detecting the flow rate from the characteristic parameter 8 of the memory 7 and the duty ratio. In such a water circulating device, the output flow rate of the pump is detected with a high accuracy from the measured duty ratio by the characteristic parameter 8 indicating the relation between the duty ratio and the flow rate, which is previously written into the memory 7.
|
