Abstract
Electromagnetic (EM) brakes are widely used but consume electricity continuously to maintain their activated state. In this letter, for efficient braking and idling of robots and vehicles, we proposed a concept of a brake mechanism using a permanent magnet for the amplification of the pressing force between brake pads, allowing for the brake torque to be steplessly regulated by a minimal external force. The prototype of the proposed mechanism was developed with a newly devised compensation spring—not the conventional conical coil springs—comprising two linear springs to shorten the pad-detaching stroke. For proof of concept, evaluation experiments based on the Japanese Industrial Standards were conducted. Both the maximum static and average dynamic friction torques increased to 161.0% and 192.9%, respectively, when identical pads of an EM brake were used for comparison. Power saving was also achieved when braking for longer than 0.43 s; the torque–energy efficiency increased by 8.7 when measured for 1.0 s, successfully revealing the effectiveness of the proposed principle. Further, based on the force–displacement characteristic of the compensated magnet, the theoretical response time was numerically analyzed as 13.6 ms—comparable to the contrasted EM brake—validating the actual behavior of 14.0 ms.
Highlights
Electromagnetic (EM) brakes are widely used but consume electricity continuously to maintain their activated state
Experiment 1: Comparison of Static Braking Torque To investigate the property of the 2nd prototype in the same way as the experiments in Section III, its maximum static friction torque at magnet–magnet distance x = 0 and control force in the range of 0 ≤ x ≤ 1.5 mm were measured and integrated with respect to x to derive the control work required for disabling the brake
The attractive force of permanent magnet (PM) in the 2nd prototype is so strong that its control work E required for an actuator to fully pull out the control rod is 796.8% of that of the EM brake E, the compensation reduced it to 27.4% of E
Summary
Electromagnetic (EM) brakes are widely used but consume electricity continuously to maintain their activated state. For efficient braking and idling of robots and vehicles, we proposed a concept of a brake mechanism using a permanent magnet for the amplification of the pressing force between brake pads, allowing for the brake torque to be steplessly regulated by a minimal external force. Evaluation experiments based on the Japanese Industrial Standards were conducted Both the maximum static and average dynamic friction torques increased to 161.0% and 192.9%, respectively, when identical pads of an EM brake were used for comparison. INTRODUCTION LECTRIC brakes are used in various mechanisms to control the speed of motion Because they do not require large and heavy external power sources such as hydraulic or pneumatic pumps, EM brakes are favored for machines with strict limitations of volume and mass [1]. Active cooling by fans or thermoelectric coolers requires even extra power
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