Gaseous fluid pump and liquid spray apparatus incorporating such a pump

Claim 1

A gaseous fluid pump for a liquid spray apparatus including a portable tank containing liquid to be sprayed and adapted to be carried by an operator, said pump comprising a resilient deformable body including flexible sidewalls of a substantially concertina configuration having convolutions and an end wall at a lower end of said sidewalls forming a variable volume chamber, a footplate, said body terminating in a peripheral flange, means securing said flange and body to said footplate, said footplate having an air inlet opening with a check valve providing flow of ambient atmosphere into said chamber and an air outlet opening having a check valve providing air flow from said chamber, conduit means connected to said outlet opening and communicating with said tank, said body collapsible in a direction towards said footplate in order to reduce the volumetric capacity of said chamber and displace air therefrom to pressurize said tank, said footplate securing said body under a foot of a wearer in such a way that, by the heel to toe engagement of the respective foot with the ground as he walks, the wearer causes successive compression and expansion of the internal volume of the chamber by successively loading the chamber to collapse the concertina configuration by applying his mass to it and unloading the chamber, a projection in said chamber extending from said end wall which is formed by said pump body at the lower end of said sidewall, said end wall being the part of said body that engages the ground during the heel to toe engagement of the respective foot with the ground as the wearer walks, said chamber including a depending projection which extends into said chamber from the upper end thereof, said depending projection defining a recess cooperable with said projection, said depending projection having an aperture therein providing communication between said deformable body and said inlet and outlet openings, said depending projection constituting a continuous peripheral wall defining said recess for receiving said projection therein with the concertina convolutions of said deformable body having their inner circumferentially extending edges in contact with the outer surface of said depending projection when said body is collapsed.