Patent ID: 8157604

Claim:
An electrical linear motor for propelling a marine vessel through a liquid medium, comprising: a housing secured to the marine vessel and submerged in the liquid medium; an insert within the housing, the insert having internal walls defining an internal passage through the insert and at least two electrical coil windings disposed on the internal walls; a thruster subassembly including a magnet holder, an internal channel with check valve, and a front cover, the thruster subassembly being disposed between the internal walls of the insert, the thruster subassembly further having a longitudinal axis coinciding with a longitudinal axis of the insert; at least two permanent magnets attached to the magnet holder of the thruster subassembly and maintained in sufficiently close proximity to the electrical coil windings so that an electromagnetic field created by a controlled energizing of the electrical coil windings interacts with a magnetic field from the permanent magnets to provide a reciprocating linear motion to the thruster subassembly; wherein the check valve is in an open position during a back stroke of the thruster subassembly so that the liquid medium flows freely through the thruster subassembly internal channel and wherein the check valve is closed during a working stroke of the thruster subassembly so that the front cover of the thruster subassembly displaces the liquid medium and thereby propelling the marine vessel through the liquid medium.