Linearmotor

A linear motor (English linear motor ) is an electric drive unit. Other than the common rotating machine, a linear motor causes the driven objects it is not in a rotating movement, but slides on a rectilinear or of curved path ( translational motion ). The term of the linear motor is also used for drives in which the rotor rotates, but only partially surrounded by the stator (for example platter or washing drum drives ). Actuators for linear movements such as solenoid or voice coil, the principle does not allow any extension shall not be referred to as linear motors, but taken together only under the additional term linear actuator with linear motors.

The linear motor was invented before the rotary motor. 1854 was Charles Grafton Page a solenoid linear motor with crank patented (U.S. Patent 10480 " Improvement in electro - magnetic engines" ). The machine was intended for propulsion of locomotives.

Principle of operation

Basically rotary motors of all principles could by a projection, which on a straight line depicting the circular air gap, are converted into the linear motors, wherein the circularly arranged first electrical field windings (stator) are arranged on a flat road. The rotor which rotates in the three-phase motor, is drawn in the linear motor of the longitudinal magnetic field on the moving route. Hence also the frequently used term traveling wave machine.

In practice always be either asynchronous ( the magnetic field is not rigidly coupled with the movement ) or synchronous machines in a broader sense is used ( which also includes linear and linear reluctance stepper motor). The use commutated DC machine is possible but not common.

The required distance between the rotor and linear winding can be held, for example, with wheels, air cushion or by floating on a regulated electromagnet.

Industrial use

Linear motors are used in machine tools, positioning and handling systems in machining centers. Conventionally, feed forces generated by a rotating electric motor, and implemented in a transmission in a translational movement. The movement is thus brought about indirectly. Linear motors allow it, however, directly represent a translational motion, it is called therefore also direct drives.

Linear motors have the advantage of high accelerations of up to six times the acceleration due to gravity and speeds of up to 800 m / min (48 km / h) in this area. The maximum forces that can be achieved with asynchronous Polysolenoid linear motors, currently at 30 kN. Also concepts with cooled superconducting coils to be developed for achieving even higher mechanical forces. In addition, they are more suitable because of the few rubbing together parts for use in clean rooms.

Linear motors are often used in positioning devices or various other types of machines, such as ultrasonic microscopes, plasma cutting machines, laser cutting machines and waterjet cutting systems. Linear motors are also suitable as a pump for liquid metals (eg sodium loop in nuclear power plants ), the coils are permanently mounted and bring the liquid metal itself as a runner in the flow pipe in motion.

Linear motors are used for rail drives ( Transrapid / RailCab HSST or roller coasters ).

Such as electric toothbrushes, electric shavers, oral irrigators are amplified linear motors because of the many design advantages now in household small electrical appliances installed. A stator here are magnets made of neodymium-iron- boron used.

For use in the art of data processing

With the so-called " Winchester removable disk system " IBM - 3330 linear motors came to replace the existing hydraulic actuators of hard disk drive used.