Patent attributes
A reservoir pump in which liquid supplied from a container in which the pump is installed enters a pressure chamber with respect to which a piston reciprocates in suction and compression strokes. The chamber communicates with a reservoir, (the supply) so that liquid is supplied into the chamber in the suction stroke of the piston and transferred under pressure into the reservoir during the compression stroke. The chamber is open to supply and to the reservoir via one-way valves which open during the suction and compression strokes, respectively. A passage providing an orifice with a cross section much smaller than the cross section of the opening into the chamber, which communicates the chamber with the supply, is open via another one-way valve during the suction stroke. Air enters through the passageway. This air is compressed during the compression stroke. Sufficient compressed air is delivered together with the liquid into the reservoir so as to accumulate sufficient pressure to pressurize the fluid when released from the reservoir for spraying thereby counteracting any build up of remnant liquid in the pressure chamber, which would decrease the volume of air in the chamber on successive strokes and prevent complete discharge of the liquid from the chamber into the reservoir and from the reservoir to allow pressurized liquid to be sprayed.
