Fluid metering device

Claim 1

A fluid metering device for dispensing a selected fluid volume comprising a combination of an electrically operated pump of the type adapted to pump a discrete volume of said fluid in response to each electrical pulsing thereof, said pump having an inlet and an outlet and a solenoid which is adapted to cause pumping operation thereof when electrically pulsed, said pumping operation consisting of the dispensing of a discrete fluid volume for each electrical pulse, and a source of said dispensed fluid having a first conduit connected to supply said fluid to said pump inlet, a second conduit connected from said pump outlet to deliver said dispensed fluid to a prescribed point of use, an electrically operated solenoid valve strategically located in said conduit adjacent said point of use effective to maintain said second conduit fully charged with fluid between said pump outlet and said point of use, an electrical circuit operatively connected to operate said pump including pulsing means for successively transmitting electrical pulses to said pump at a selected constant frequency and simultaneously therewith to pulse said solenoid valve into an open condition to allow the exiting flow therethrough of fluid, and means including a timer operatively connected to initiate the commencement of the operation of said pulsing means and the subsequent termination thereof after a selected duration of time such that said pulsing means transmits said pump-operating electrical pulses to said pump solenoid during said duration of time at said selected constant frequency, whereby the fluid volume dispensed at said point of use by said fluid metering device is the sum of said discrete volumes dispensed by said pump for the number of electrical pulses transmitted to said pump during the operating interval thereof as determined by said timer.