JSAE 2009 - Moving Magnet Technologies

3 The Torque Motor
A special task is the positioning of valves
and flaps, particularly in the area of air
supply and exhaust removal. These
components must often work under very
harsh conditions and have to meet high
standards of performance, reliability,
force density and precision. Sonceboz
developed the torque motor for such
tasks and has been producing more than
15 million units since the year 2000.
Several million are produced every year.
3.1 Advantages of the Torque
Motor
The high torque vs. mass ratio optimizes
weight and size. The peak to nominal
torque ratio high and the torque output
can be maximized for short time periods.
•Since the torque runs proportional to
the current, the regulation can take place
by means of simple and conventional
methods.
•Very low detent torque makes it
possible to use a minimized return
spring and thereby to reduce the holding
current.
•The design as a direct drive provides for
high reliability and service life.
•The use of permanent magnets in the
rotor and the possible integration of a
contactless sensor enable a totally
brushless solution.
•The possible integration of drive and
controller electronics enables a compact,
intelligent drive system.
.
3.2 The Operating Principle
In the torque motor, the rotor (5-6) in
Figure 1 moves over a sector of 75°.
The interaction between the rotor
magnet (5) and the stator electromagnet
(1-3) produces a torque, the direction of
which depends on the current polarity
fed into the electromagnet. Hence, any
position can be controlled by regulating
the current, the rotor (5-6) stops in the
position in which the drive torque and
the sum of the resisting torques, e.g. air
pressure or spring, of the application
compensate.
5
6
Figure 1 : Construction of the motor
4
1
3
2
4
Torque Motors