What is a direct drive motor?

Direct drive motors are any rotary or linear motors in which the load is directly connected to the motor.Direct drive motors do not require mechanical transmission components,such as gearboxes,belt and pulley systems.In other words,the motor drives the load directly.

1.Direct drive rotary motors

Rotary direct drive motors are often referred to as torque motors because they produce high torque at low speeds even when stalled.Torque motors tend to be brushless permanent magnet synchronous motors--much like traditional servo motors,but with a large number of poles.They are usually offered in a frameless design,which means they do not include a housing,bearings or feedback devices,which are purchased and integrated separately by the user.

Torque motors are often provided as frameless deigns,without a housing,bearings,or feedback device.

Another type of rotary direct drive motor is the pancake motor,also known as a Lorentz force motor or printed armature motor.These motors are brushed DC motors in which the armature winding is printed on a non-magnetic insulating disk.The armature disc is placed between two stator discs that have permanent magnets arranged at alternate north and south poles.Magnetic flux runs axially along the length of the motor and current runs radially(rather than axially as with conventional motors).According to Lorentz forces,this causes torque to be generated around the axis of the motor.

The pancake motor consists of a printed armature(rotor)between two permanent magnet stators.This gives them a very thin profile and a large overall diameter,hence the name"pancake motors".

2.Linear direct drive motor variation

(1)Flat linear direct drive motors

①A flat linear motor without an iron core has a flat magnet(a secondary part)whose primary part or forcer consists of a coil mounted on an aluminum plate.These motors have excellent speed control but produce less force than other designs.Another structural variation of the coreless motor uses two magnetic rails facing each other(sometimes called U-channel or air core linear motors).No core secondary parts or forcer,rides between the magnet tracks. These motors have no cogging and can produce very high acceleration and deceleration rates.

②Flat core linear motors can be slotted or unslotted,with slotted core designs being the more common variant.The secondary part of a slotted iron core linear motor consists of an iron back plate and iron teeth or laminates,around which the coil is wound.They have the highest resistance,but they may experience significant cogging.

③Slotted designs are considered a hybrid between ironless and traditional slotted iron core designs,as their coils are wound without iron lamination,but mounted on back iron plates.The secondary section is usually contained in an aluminum housing.These motors have fewer cogging and lower inertia than slotted iron core designs,but they are also less mechanically capable.

Flat linear direct drive motors can have an ironless(top),slotted iron core(middle),or slotless iron core(bottom)construction.

(2)Tubular linear direct drive motors

Another structural variation of a direct-drive linear motor is to contain a magnet in a cylindrical tube and contain the windings in a forcer or thrust block surrounding the tube.Like their flat counterparts,tubular linear motors can be made with or without iron in secondary parts(i.e.iron core or no ironless).The main advantage of tubular linear motors is that their symmetrical design allows all magnetic fluxes to be used to generate thrust.

Tubular direct drive linear motors can be of iron core or ironless type.They offer an alternative to pneumatic and ball screw actuators with high speed and high thrust capabilities.

(3)Non-magnetic-track direct drive linear motors

ALM proposed the Magnetic-track-free(MTF)linear motor for the first time in industry based on the innovation in the magnetic field theory.Compared with competitors,MTF linear motor module can save on large amounts of rare-earth materials bring 70% cost saving,particularly on long track linear motor modules.The characteristic of our product is that the stator of the linear motor module has no magnetic track.The MTF linear motor module puts the magnet inside the actuator,and when the actuator moves,the corresponding magnet moves.It can effectively overcome the disadvantages of large magnet consumption and low utilization rate of the conventional linear motor module.Thus,the cost of linear motor module is greatly reduced and safety is improved.

 Magnetic-track-free(MTF)linear motor can save on large amounts of rare-earth materials bring 70% cost saving.

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