Pump with high torque drive

A pump apparatus for moving a liquid, the pump apparatus comprising:

• an electric motor configured to generate a rotational output, the electric motor comprising:
• a rotor configured to rotate about a rotational axis, the rotor comprising a permanent magnet array disposed annularly around the rotational axis;
• and
• a stator configured to be electrically energized to generate magnetic flux that causes the rotor to rotate, the stator comprising:
• a plurality of coils, the plurality of coils arrayed along the rotational axis;
• and
• a plurality of circular spur arrays that are arrayed along the rotational axis, each circular spur array of the plurality of circular spur arrays respectively comprising:
• a plurality of spurs that are arrayed in a circle coaxial with the rotational axis, wherein each spur of the plurality of spurs is configured to be polarized simultaneously by a coil of the plurality of coils to generate magnetic flux to rotate the rotor relative to the stator;
• a rotor shaft connected to the rotor to rotate with the rotor, the rotor shaft extending from the rotor in a first axial direction along the rotational axis;
• a drive including a drive nut and a screw that extends within the drive nut, the drive nut configured to rotate with the rotor to displace the screw linearly, wherein the drive nut is connected to an end of the rotor shaft spaced axially outward from the stator such that the drive nut is spaced in the first axial direction along the rotational axis from the stator, the drive configured to receive a rotational output from the rotor and convert the rotational output to linear motion;
• and
• a pump comprising a pump body and a fluid displacer configured to be reciprocated by the drive within the pump body and along a pump axis to pump a fluid, wherein each of the plurality of coils lacks winding endturns that extend axially beyond any spur of the plurality of spurs such that at least one spur of the plurality of circular spur arrays is located closer to the fluid displacer than any of the plurality of coils;
• and
• a frame that holds both of the stator and the pump body stationary while the rotor moves the fluid displacer via the drive, wherein the frame extends radially wider than both of the plurality of circular spur arrays and the rotor, wherein the electric motor is mounted at a first end of the pump frame and the pump body is mounted at a second end of the pump frame opposite the first end of the pump frame.