| 摘要 |
PURPOSE:To enable to vary the flow rate of a pump drastically through slight change of the discharge pressure, by imparting a spring having a fairly small spring constant with a prescribed preset load, and arranging the spring in series with a spring seat and other springs. CONSTITUTION:A spring 22 is imparted with a prescribed preset load by means of adjust screw 24 and a spring seat 23 such that the preset load is equal to the force produced when a pressure PD' is acted to a piston 7'. Therefore, in case that the load of a spring 9' or the sum of the loads of springs 9' and 10' is smaller than the load of the spring 23, that is, in case that the discharge pressure is lower than PD', a spring seat 21 is urged onto a stepped portion 20' of a case 20 by the differential force. Hence, since the spring 22 holds the preset load in this state, the flow rate of a pump can be varied drastically through slight change of the discharge pressure. |
