The most basic definition of a direct drive motor is a design that allows the motor to be directly connected to the drive load. This eliminates mechanical transmission elements that often increase the smoothness of drive systems such as gears, couplings, belts and pulleys, and chain drives. Direct drive motors are sometimes also called torque motors, Lorenz force motors, or pancake motors.
▲The conventional motor and drive unit on the left shows some mechanical drive components, such as the gearbox and drive gear eliminated in the direct drive motor on the right.
▲A typical rotary direct drive motor, such as Kollmorgen's built-in servo motor, has higher torque density and higher precision compared to non-direct drive servo motors.
Eliminating these components can significantly improve system performance in several key ways. For example, it can improve load acceleration, reduce power consumption, reduce system inertia, and improve accuracy by reducing maintenance.
One of the most common types of motors used in direct drive setups is the brushless permanent magnet synchronous motor. These motors often have an axial height smaller than their diameter, hence the nickname "pancake" motors. These types of motors also typically have a large central bore.
These variations of electric motors can be defined in several ways. For example, there are rotary motors and linear direct-drive motors, although designers may be more familiar with the rotary type because it is more common and closer to a traditional rotary motor. For linear direct-drive motors, one way to think of them is as rotary motors that are axially cut, roll flat, and directly connected to the load.
▲Direct-drive linear actuators, such as these devices from Intel LiDrives, use direct-drive linear motors with mechanical bearings and moving brackets.
Another way to classify direct drive motors is by whether they are enclosed. For example, enclosed motors are housed within a motor frame. There are also unenclosed or frameless motors. These motors can be directly integrated into the machine without bearings or any type of sensors.
Disclaimer: This article is a reprint. If there are any copyright issues, please contact us promptly for deletion (QQ: 2737591964). We apologize for any inconvenience.
