The invention generally concerns a submersible well pumping system comprising
an axially elongated housing and a multi-chamber hydraulically driven diaphragm
pump suspended in a well. The pump is driven by a self-contained, closed hydraulic
system, activated by an electric, pneumatic or hydraulic motor. Several embodiments
are used to reverse the flow of working fluid into and out of the working fluid
sub-chambers of a two chambered diaphragm pump to operate the diaphragm pump over
all operating conditions including starts and stops, and low speed. Generally,
the embodiments sense the end of the pumping stroke, either directly or by time.
When the end of the pumping stroke is sensed, the direction of flow is reversed
by changing the state of a directional valve, operating a reversing clutch, or
by deactivating one prime mover-auxiliary pump and activating a second that operates
in the reverse direction.
