Abstract: A small diameter linear motor is relatively short in length, and includes a hollow elongated mover, and a stator having a plurality of annular spaced apart stator teeth. Individual electrical coils are wound from individual uninterrupted single wires extending from outside of the assembly in the spaces between the teeth to avoid the need for electrical connections between the coils. The stator assembly and mover are dimensioned to fit within the hollow interior of a ferromagnetic tube. In another form, the linear motor includes a mover and a stator, the stator including a set of coils for producing a series of electromagnetic fields extending at least partially in an axial direction when energized with an electric current and a stator core defining a plurality of spaced-apart transversely disposed coil receiving slots and an annular axially extending mover receiving bore.

Abstract: A new and improved linear motor-pump assembly and method of using it for downhole use. The assembly includes a cartridge unit with a linear motor attached threadably between a discharge housing assembly adapted to be secured removably to a cable for hoisting the cartridge unit through the production tubing of a well and a suction housing assembly for facilitating the pumping of well fluids from a downhole well. The linear motor includes a mover adapted to engage threadably a stop valve for permitting one-way flow of fluid through the mover and into the discharge housing for discharge into the production tubing. For increased pumping efficiency, the suction housing and check valve are replaceable with a lifting pump and piston respectively. Thus, the assembly is usable in both shallow and deep wells.

Abstract: A new and improved control system for monitoring and controlling the operation of a downhole linear d.c. motor-pump assembly and a method of using it for producing a sufficient reciprocating pumping action to lift well fluid through the producing tubing of a well to the ground surface. The system includes a surface monitoring station that is in radio communication with a plurality of remote downhole motor-pump assemblies. Each motor-pump assembly has a surface motor controller, a downhole motor-pump cartiridge unit that is adapted to be received in a downhole cartridge sleeve assembly that maintains the cartridge unit in a stationary position for pumping purposes. The motor-pump cartridge unit may be raised or lowered by a control cable within the production tubing for helping to facilitate the repair or replacement of the motor-pump cartridge unit.