What Is a Torque Motor?
A torque motor is a type of motor that provides high starting torque, decreasing as rotational speed increases. It operates stably across a broad speed range, making it ideal for rollers and winding devices. Torque motors are particularly effective at low speeds, where high torque is essential for tasks such as winding, where initial low torque and high speed are needed, transitioning to high torque and low speed as the diameter of the wound material increases.
Uses of Torque Motors
Torque motors are integrated into equipment for constant-speed winding of sheet materials like cloth, paper, rubber, or linear materials such as metal wire, cable, or thread. They are utilized in applications requiring constant tension, including feed rolls, compensation for roll tension loss, small cranes, belt conveyor drives, as well as for tightening valves and screws, and automating door movements.
Principle of Torque Motors
The RPM-torque characteristic curve of a torque motor, unlike other motors, steadily decreases, showcasing a droop characteristic. This allows the torque to decrease with increasing rotational speed to maintain balance with the load. By adjusting the applied voltage, this droop characteristic can be tuned, making torque motors adaptable for applications requiring static torque for constant angular velocity operations. They are also efficient for tasks needing frequent starts and stops due to their high starting torque and low starting current requirement.
Other Information on Torque Motors
How Torque Motors Are Used as Brakes
Torque motors can also function as brakes to maintain constant tension in unwinding applications, utilizing their braking characteristics in two main ways:
1. Reverse-Phase Braking
Utilizes the torque generated when the motor rotates against the direction of the applied AC voltage’s magnetic field. This braking force is effective from zero rotation speed, making it suitable for maintaining tension even when the motor is stopped.
2. Eddy Current Brake
Employs the braking force generated by the eddy currents when a DC voltage is applied, working independently of the motor’s rotation direction. The brake force increases with rotation speed, stabilizing at higher speeds, ideal for maintaining tension in both forward and reverse directions at high rotational speeds.