Patent ID: 8365762
Filing Date: 2013-02-05
Classification: B64D,Y10T

Abstract:
1. A system for dispersing a flowable substance, including liquids and dry bulk materials, from an aircraft onto the ground at a predetermined rate of coverage, comprising: a tank with an outlet, adapted to be carried by the aircraft, for containing the flowable substance; a gate aligned to engage said outlet; a fluid driven actuator coupled to selectively move said gate between a closed position and variable open positions whereby the flowable substance is dispersed at controlled rates though a gate opening created between said outlet and said gate; a fluid supply; a transfer controller, which outputs a transfer signal that corresponds to a time varying fluid transfer rate; plural valves, plumbed in parallel between said fluid supply and said fluid driven actuator, each having a corresponding input to receive an actuation signal that enables a closed state or an open state; plural means for limiting the rate of fluid flow corresponding to said plural valves; a valve drive, which is a processor programmed to couple a sequence of valve open-state combinations that are updated at repetitive predetermined time intervals, coupled to said corresponding inputs of said plural valves, and thereby generate a sequence of valve actuation signals that result in a combined fluid flow rate through said plural valves selected to track the time varying fluid transfer rate defined by a modulated transfer signal within a margin of error, which is defined as the lowest incremental flow rate, during one of said predetermined time intervals, of one of said plural valves and corresponding means for limiting flow; a position sensor engaged with said fluid driven actuator and operable to output a feedback signal related to the actual time varying position of said fluid driven actuator; a feedback modulator coupled to modulate said transfer signal with said feedback signal to produce said modulated transfer signal, and wherein said valve drive is further operable to pulse width modulate at least one of said plural valves between a closed state and an open state to achieve an average fluid transfer rate within one of said predetermined time intervals that is less than said margin of error.