Backpack sprayer with an expandable accumulator chamber

A backpack sprayer apparatus comprising:

• a supply tank suitable for holding a supply of fluid, and configured and dimensioned to be mounted on the back of an individual operator;
• expandable accumulator means, having an expandable volume, for accumulating fluid under pressure as its volume expands from an initial volume to an expanded volume, and for discharging said fluid under pressure as its volume contracts from the expanded volume to the initial volume, said accumulator means containing an inlet opening;
• pump means, positioned adjacent to the bottom of said supply tank and in fluid communication therewith, for pumping fluid from said supply tank into said expandable accumulator means through the inlet opening;
• intake valve means, associated with the inlet opening of said expandable accumulator means, for enabling a unidirectional flow of fluid from said pump means to said expandable accumulator means;
• discharge valve means, associated with the inlet opening of said accumulator means, for controlling the discharge of the fluid from said accumulator means.

A sprayer apparatus comprising:

• a container for holding a supply of fluid;
• accumulator means, having an expandable volume, for accumulating fluid under pressure as its volume expands from an initial volume to an expanded volume, and for discharging said fluid under pressure as its volume contracts from the expanded volume to the initial volume, said accumulator means containing an inlet opening and having a sealing flange bounding the inlet opening;
• a coupling, configured and dimensioned to receive and secure said accumulator means in an operable position, said accumulator means being secured in said coupling such that the sealing flange of said accumulator means maintains a close sealing fit with said coupling;
• pump means, in fluid communication with said container, for pumping fluid from said container into said accumulator means under pressure through the inlet opening, wherein the pressurized fluid accumulated in said accumulator means causes the seal between the flange and said coupling to be reinforced;
• intake valve means, associated with the inlet opening of said accumulator means, for enabling a unidirectional flow of fluid from said pump means to said accumulator means;
• discharge valve means, associated with the inlet opening of said accumulator means, for controlling the discharge of the fluid from said accumulator means.