Flow control for variable pump - has pump positioner control valve actuated by throttle differential via pilot pressure varying valve

摘要

The flow control system is intended for a variable pump (10) and comprises a flow measuring throttle orifice (14) in the delivery lines (13) whose pressure differential acts on a control valve (19) arranged in the line to the positioner (25) of the pump. A valve (16) is arranged in series with the control valve to alter the actuating pressure on that valve (19). The valve (16) may be a pressure limiting valve, or it may be an electrically operable valve, particularly a proportional pressure valve. The valve (16) may have a fixed downstream throttle (21) which may be contained in the valve spool.