Torque motors as external rotor motors | by Fischer in Germany


Torque motors as external rotor motors from Fischer

Whether with an internal rotor or an external rotor, torque motors are extremely powerful direct drives that develop enormous torque in a small design.

Torque motors are referred to as frameless motors because they are not enclosed by a housing in the classic sense. Unlike conventional drives, the torque alone, i.e. not the power, determines the size of the motor. Basically, torque motors of any size are considered true powerhouses.

Torque motors – advantages:

Outstanding radial runout characteristics

Very energy-efficient

High efficiency

High power at low speeds

Low-noise operation

Here you can find more information on the following areas:

With the torque motor it is not only possible to generate a rotary movement, but also to position or to perform clearly defined cycle steps.

With the torque motor, a gearbox can be dispensed with. Of course, the winding can be designed user-specifically. Thus, the torque motors are individually planned and manufactured by us, depending on the purpose of use.

If a conductor loop is moved in a magnetic field, a voltage is induced into this conductor loop. A current-conducting coil generates a temporally changeable electric field that interacts with the constant magnetic field of the rotor. The resulting force is used to generate the rotary motion.

A torque motor consists of two components: the stator with coils and the rotor with permanent magnets. A distinction is made between slotted, non-slotted and ironless direct drives.

The torque motor enables a very high torque with a defined speed range. The distance between the stator and rotor (air gap) is decisive for the magnitude of the torque.

A stable bearing system guarantees a constant air gap. A measuring system is used in order to determine the motor position at any time.

Customer-specific electric motors are almost the rule at Fischer Elektromotoren. The electrical connection options differ entirely depending on the later use and installation situation and are implemented individually.

  • Cables with plugs – variable cable lengths
  • Open-ended cables with wire end ferrules – variable cable lengths
  • Built-in socket on motor housing

A second cable output may be necessary depending on how complex the customer specifications are with regard to additional components (for example measuring systems, temperature sensors, etc.) Fischer electric motors are equipped with precisely the connections that the customer requires.

The listed performance data are feasibility proposals, our direct drives are always customer-specific.

Catalogue data


Measurement technology

Motors from Fischer Elektromotoren GmbH are tested according to the EC directive 73/23/EEC and the EN 50178 and EN 60204 standards.
These test procedures are carried out prior to delivery:
  • High-voltage test
  • Partial discharge test
  • Insulation test (VDE measurement)
  • Pole position test
  • Resistance measurement of phases and temperature sensors
  • IInductance measurement
  • EMF measurement

State-of-the-art measurement technology for quality assurance.

We use state-of-the-art measurement technology for measuring all motors. The parameter sets for commissioning as well as the peak and nominal values of the motor are determined on our test benches. Thermal motor protection and water cooling are thereby taken into account. All mechanically installed components are measured using the latest measurement technology such as 3D and height measuring machines.