A valve device comprising a stator 22 having a predetermined number of coils arranged with substantially equal intervals in peripheral directions of a stator core, a rotor having a plurality of permanent magnet magnetic poles 29 at positions corresponding to the coils on an outer peripheral surface of the stator 22, a current carrying means 37 commutating a direct current supplied from a power source through the rotor 28 and applying the current to the coils of the stator 22, a shaft member located in a center of the rotor 28 and being movable in a direction of the shaft in response to rotation of the rotor 28, and a valve member 45 opening and closing by movement of the shaft member 30 for providing excellent responsiveness of valve opening and closing operations.

A drive roller has a brushless D.C. motor with a stator or armature mounted on a fixed shaft and directly driving a 16 pole permanent magnet rotor mounted inside a roller tube. A motor controller drive supplies three-phase power to a Y-connected three phase winding having three groups of two coils, forming twelve electromagnets which drive the rotor. The modular motor is readily built in one inch increments to supply one lb-in of torque for each increment. The controller operates at a relatively low frequency of 15-75 Hz. Hall effect sensors provide feedback on motor speed and position. The armature laminations are relatively thick because of the relatively low power necessary to drive the motor and the resultant relatively low eddy currents present in the motor core. A 4.0 lb-in torque motor with a rotor and stator length of four inches will draw approximately 0.8 amps consuming about 15 Watts.

The drive roller of this invention utilizes a brushless D.C. motor which has a stator or armature mounted on a fixed shaft which directly drives a permanent magnet rotor mounted inside a roller tube. A variable frequency drive supplies three-phase power to a Y-connected three phase winding which is composed of three groups of two coils. Thus twelve electromagnets are formed which drive the permanent magnet rotor which has sixteen poles. The brushless D.C. motor is of a modular design and can be easily built in one inch length increments to supply one lb-in of torque for each one-inch increment. The variable frequency controller operates at a relatively low frequency of 15-75 Hz. Hall effect sensors are used to provide feedback on motor speed and position. The armature laminations making up the brushless D.C. motor core are also relatively thick because of the relatively low power necessary to drive the motor and the resultant relatively low eddy currents present in the motor core. For a motor with a 4.0 lb-in design torque and a rotor and stator length of four inches, the current draw will be approximately 0.8 amps consuming about 15 Watts of power.

An electric-motor assembly for installation in a borehole to power a downhole tools such as a pump has a first impermeable tube defining an axis and a stator fixed in the tube and having a series of coiled windings and laminations and electrically insulating potting in which the laminations and windings are imbedded. The windings have a connection to an electronically controlled power supply. An annular rotor in the tube radially surrounding the stator includes a permanent magnet coaxial with the windings. The tube seals the stator and rotor from the environment.

A prime mover using a split coil for magnetically inducing movement of a steel piston. The magnetic effects are emphasized in higher reciprocating movement by the proximate introduction of a permanent magnet. The prime mover is sparkless, brushless, quiet, low friction, and can operate on a wide array of voltages, including high frequency very low voltage signals.