Pump having reciprocating pipe and slidably supported hollow body

Claim 1

A pump of the type adapted to be lowered into a body of fluid for pumping fluid therefrom comprising a pipe having an open lower end and an upper discharge end for discharging pumped fluid from a point above the body of fluid, said pipe being reciprocal through a normal pumping stroke, first check valve means for permitting flow into said pipe through said open lower end, a hollow body slidably supported upon the lower end of said pipe and defining a cavity into which said open lower pipe end extends, seal means interposed between an upper end of said hollow body and said pipe for sealing the upper end of said cavity, said hollow body having not portion that is engaged by said pipe upon normal pumping reciprocating of said pipe so that said hollow body is not physically reciprocated by contact with said pipe upon normal pumping reciprocation of said pipe, an opening formed at the lower end of said hollow body, and a second check valve for controlling the flow through said hollow body opening for permitting flow into said hollow body cavity and for precluding flow out of said opening, said second check valve comprising a first element fixed relative to said hollow body and a cooperating second element adapted to be fixed relative to the body of fluid, and said pipe being reciprocated between a raised position and a lowered position during the normal pumping reciprocation thereof, the reciprocation of said pipe into said raised position effecting a pressure difference upon said hollow body by the fluid in the fluid body for moving the first element of said second check valve away from the second element of said second check valve for permitting flow of fluid into said hollow body cavity solely due to fluid pressure variations, movement of said pipe in a downward direction being effective to permit said hollow body to move for bringing said first element into sealing engagement with second element for pressurizing the fluid in said hollow body cavity for driving said fluid upwardly through said first check valve into said pipe and be discharged through said upper discharge end.