Direct drive rotary actuators

Rotary Actuators

Providing constant torque and fast positioning

on a limited angular stroke

MMT rotary actuators have been designed to provide an efficient, contactless, direct drive rotary motion on a limited stroke . They are the result of several years of engineering at MMT and can achieve the hardest automotive requirements. A large variety of designs is now available, based on the use of ring, disc or even tile shaped permanent magnets.

The main features of this family of actuators are:

· A constant torque which is independent of the angular position for a given current

· A linear torque versus current characteristic

· Bi-directionality

· High torque/ÖWatt/kg ratio

· A contactless actuation principle

4-pole disk magnet rotary actuator

Additional functions, such as a magnetic return spring or analog contactless position sensing can also be implemented.

Thanks to the linearity of the torque versus current characteristic and to its independence of position, it is possible to operate our actuators in an open-loop against a spring or in a simple closed-loop mode by using a position sensor.

Basic Principle

Torque versus position graph

The basic working principle is explained here above : a thin 2-pole permanent magnet is glued on a magnetic yoke. The stator is a 3-pole ferromagnetic part and the central pole is surrounded by a coil. When the coil is energized, the polarity of the central pole is opposite to that of the other poles, which results in a net torque on the magnet.

That torque is independent on the magnet’s position and proportional to the current input.

Strokes up to 150° can be achieved with available torque up to 4 Nm.

Main applications

Manifold Tuning Valve (MTV) actuator

MMT rotary actuators are particularly well suited for applications requiring high torque, small size actuation devices that can withstand millions of cycles in a demanding environment (dust, vibrations, etc…).

Automotive valve (EGR, MTV, MVRV, Variable Geometry Turbo, …) control is typically a field in which MMT direct drive systems are efficient. These actuators provide large boost capacity and high speed with the reliability of contactless actuators.

Our rotary actuators are also used in applications such as:

· Reactive computer peripherals

· Automatic payment machines

· Laser beam deviation control

· Pressure tuning valves

· Bypass proportional valves