| 摘要 |
PURPOSE:To rapidly raise the number of rotations of a test body and to stabilize the same, by closing a solenoid valve when the number of rotations of the test body reached the upper limit value of a comparing circuit and opening the same when reached the lower limit value thereof. CONSTITUTION:When a rotor 1 is rotated, the number of rotations of the rotor 1 is detected by a photocell 6 and the detection signal thereof is applied to a comparing circuit 8 through a DC converter 7 and a conversion signal is compared with the reference voltage of a rotary number setting device 9 in said comparing circuit 8. When the number of rotations of the rotor 1 reaches an upper limit value n1, the comparing circuit 8 generates an output signal and a solenoid valve S0l1 is closed and, at the same time, a solenoid valve S0l2 is opened. Therefore, air of an air source 4 passes through a flow control valve S2 in a small flow amount side to be supplied to an air nozzle 3. Contrarily, when the number of rotations of the rotor 1 reaches a lower limit value n2, the valve S0l2 is closed and the valve S0l1 in a large flow side is opened. By this method, the number of rotations of the rotor 1 is stably held to the range of the upper limit value n1 and the lower limit value n2 set by the comparing circuit 8. |
