Electromagnetic clutch

The concept of magnetic coupling is used as a generic term for a range of coupling types, whose function is based on the effect of a magnetic field. To these types of couplings include among others, the electromagnetic clutch, the magnetic powder clutch, magneto-rheological fluid coupling, and the non-contact magnetic coupling.

Electro magnetic coupling

An electromagnetic clutch is an electrically remote-controlled, a force- or form-fitting coupling.

The colloquially referred to as a magnetic coupling form is similar in basic structure of a single dry. The drive side is fitted with a solenoid, which usually does not rotate itself by the magnetic field reaches the rotating coupling partner via an air gap. In dependence on the applied electric voltage, a different strong magnetic field acts on the slidably mounted pressure plate of the driven side. The clutch plate is clamped or axially movable and pressed against a fixed part and thus transmits the rotational movement.

The clutch plates can be serrated.

Magnetic couplings are easy to control (remote ). In motor vehicles, it is often installed for switching of compressors and pumps. When starter whose axially displaceable bearing anchor serves as a movable element. It is drawn in by the excitation field in the stator, and the pinion meshes with the externally toothed flywheel of the internal combustion engine.

Magnetic couplings were used in machinery and equipment for connecting and disconnecting of drives as well as the direction of rotation.

Powder clutch

The magnetic powder clutch is a friction clutch. In the gap between the drive plate and driven plate is a metal powder or Metallgel. The housed in a pressure plate solenoid magnetizes the metal and stiffened it. This achieves a force-fitting connection. By changing the applied voltage, a fixed connection or slip is generated. Without power, no forces are transferred because the metal particles lie down by the centrifugal force to the drive plate. The magnetic powder clutch can be used as a start, but here a derivation of the heat from the slip operation must be guaranteed. Following the same principle works in the magnetic particle brake.

Magnetorheological fluid coupling

A magneto-rheological fluid coupling, short MRF clutch is constructed as a magnetic powder clutch, in principle. Instead of the metal powder used, however, a magnetorheological fluid is used. This changed under the influence of a magnetic field consistency from liquid to gel too tight. The advantage of MRF clutch to a metal powder coupling is the better sealing of the transmission medium to the outside, a low internal friction in the disconnected state ( less heat, less wear), as well as a better heat dissipation, allowing a prolonged or frequent operation in the slip state. Magnetorheological couplings can be made ​​into slices, bell and other forms.

Non-contact magnetic coupling

Your various types are used, among other things, to achieve power transmission through the walls ( eg hermetically closed vessel) through it. You can work with permanent magnets or electromagnets. An example is the set temperature adjustment on contact thermometers.

Magnetic couplings with bilateral permanent magnets find wide application in magnetic drive pumps. They are a variant of the centrifugal or positive displacement with respect to the sealing system dar. The non-contact, magnetic power transmission, the pump housing is not interrupted by a drive shaft. Main area of ​​application is the promotion of toxic, odorous or hazardous fluids, eg, in the chemical and petrochemical industries.

Besides rotary and linear variants exist, eg for hermetically sealed pneumatic working cylinder or for non-contact power transmission in magnetic suspension balances.

The driving side of a non-contact magnetic coupling can also be the rotating field of the stator of an electric motor. In this case one speaks of canned motors. Examples are magnetic stirrer, heating circulation pumps, aquarium pumps, water meters, and drives the rotating anode X-ray tubes.

In older vehicle speedometers one provided with a return spring aluminum plate was measured by a tachometer mounted on the shaft permanent magnet moves through induction of an eddy current.

Hysteresis

Operation: Two segmental permanent-magnet ring magnets (outer discs ) enclose an (average ) hysteresis. Face each other like poles, affects a maximum magnetic field on the hysteresis. This causes a flow line of force in the circumferential direction within the hysteresis, whereby the maximum torque is generated. Unlike poles face each other, affects the slightest magnetic field on the hysteresis and the power line river runs right through them. This causes the minimum torque. By changing the angle of the pole overlay the torque is infinitely adjustable, and since there are no contacting surfaces, the setting will be retained indefinitely.

Benefits of Hysteresebremsenkupplungen:

• No breakaway torque occurs
• Noiseless operation
• No wear because the transmission is not based on friction