Pumping arrangement control device

摘要

An arrangement for pumping fluids includes at least one variable-output pump and a drive therefor. An auxiliary pump is also driven by the drive and discharges control fluid at a rate corresponding to the speed of rotation of the drive into a discharge conduit in which a variable flow-through cross-sectional area throttle valve is located. The pressure in the discharge conduit upstream of the throttle valve controls the displacement of a control slide between the two end positions thereof in one of which the control slide controls the variable-output pump so as to increase the output thereof, while in the other of such positions of the control slide the pump is controlled so as to reduce the output thereof. The throttle valve is responsive to the pressure in the discharge conduit, but can be arrested in any position thereof when the drive is overloaded so that the flow-through cross-sectional area thereof is fixed, which results in a decrease of output of the variable-output pump when the drive is overloaded. Advantageously, the throttle valve is arrested when the power input to the drive exceeds a predetermined value. The arresting of the throttle valve may be effected by using an actuating electromagnet which is energized in response to overloading conditions of the drive by a switch interposed in the electric circuit of the electromagnet and controlled by the drive.