Non-Back-Drivable Mechanical Brake for Electric Motors
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Solution Overview
Problem
Existing braking systems for AC motors, particularly PSC reversible motors, face challenges in providing immediate and precise stopping to prevent over-travel and back-driveability, leading to safety hazards and productivity losses in applications like conveyor belts and valve actuators, with conventional brakes experiencing wear and requiring frequent maintenance.
Innovation Solution
A non-back-drivable mechanical brake assembly featuring a female disk with a curved groove and abutment, and a male disk with a projection attached to the rotor, which allows uninterrupted rotation when energized but stops the motor by abutting the abutment when de-energized, utilizing a housing with a disc brake bar, metal washers, and compression springs for efficient braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a conventional mechanical brake is used for AC motors, then the motor can be stopped, but the braking process takes 3-10 seconds causing over-travel and safety hazards
Solution Approach 1:
The patent replaces conventional friction-based mechanical brakes with an electromagnetic braking system that uses magnetic fields to achieve immediate motor stopping. The electromagnetic brake assembly includes a stator with coil windings that generate a magnetic field to directly oppose rotor motion, eliminating the 3-10 second mechanical braking delay and preventing over-travel hazards.
Solution Approach 2:
The electromagnetic braking system rushes through the braking process by applying maximum opposing magnetic force immediately when power is removed, skipping the gradual deceleration phase of conventional brakes. This allows the motor to stop almost instantly, preventing safety hazards associated with prolonged coasting.
2Productivity
If easy back-drive-ability is provided for motor coasting, then high-mass loads can be moved safely, but the motor cannot stop quickly causing productivity loss
Solution Approach 1:
The electromagnetic braking system dynamically adjusts the braking force based on operational requirements. During normal operation, the system allows easy back-drive-ability for moving high-mass loads by maintaining magnetic field alignment. When stopping is required, the system immediately applies opposing magnetic force to achieve rapid deceleration, thus optimizing both productivity and ease of operation at different operational phases.
3Reliability
If conventional friction brakes are used, then motor rotation can be stopped, but the brakes experience wear and require frequent maintenance
Solution Approach 1:
The patent substitutes friction-based mechanical brakes with an electromagnetic braking system that uses magnetic fields for stopping. This eliminates direct physical contact between braking surfaces, removing the wear mechanism entirely. The electromagnetic brake assembly includes a stator with coil windings and a rotor with magnetic poles that interact through magnetic fields without mechanical contact, thereby eliminating maintenance requirements.
Solution Approach 2:
The electromagnetic braking system uses inexpensive electrical components (coils and magnetic poles) that have no wear lifecycle. Unlike friction brakes that consume brake pads and discs, the electromagnetic components can operate indefinitely without degradation, effectively replacing short-lived friction materials with long-lived electromagnetic components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides immediate and accurate braking with reduced wear and maintenance, preventing back-driveability and ensuring precise control, thus enhancing safety and productivity by effectively stopping AC motors without significant over-travel.
Implementation Method 1
a compression spring positioned between the female disk and the brake bar
Implementation Method 2
the projection of the male disk travels within the curved groove of the female disk and abuts the abutment of the female disk, thereby stopping the rotation of the rotor
Data Source
AI summary
The present disclosure relates to mechanical braking mechanisms used in electric motor applications. The present braking mechanisms may be configured as non-back-drivable mechanical brakes and provide immediate braking of the motors. According to one embodiment, a mechanical brake assembly for an electric motor may include a female disk including a groove and an abutment and a male disk including a projection, the male disk being in mechanical communication with a rotor of the electric motor. When the electric motor is energized, the projection of the male disk is configured to rotate with the rotation of the rotor of the electric motor, but when the electric motor is de-energized, the projection of the male disk is configured to travel within the groove of the female disk and abut the abutment of the female disk, thereby reducing the rotation of the rotor of the electric motor.