Elevator Braking Device Using Counter-EMF for Smooth Stops
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Solution Overview
Problem
Clutch-type brakes in elevators lack control over braking torque, leading to jerky stops during both emergency and normal operations, and require bulky, expensive systems for emergency stops, while failing to provide reduced stopping power for normal stops.
Innovation Solution
A braking device that utilizes counter-electromotive force (counter EMF) generated by a motor to provide a controlled braking torque, disengaging the braking system during emergencies and engaging it frictionally once the counter EMF dissipates, allowing for smooth and controlled stops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a clutch-type brake is used to provide sufficient braking torque for emergency stops, then the brake can handle emergency stopping requirements, but the brake cannot provide reduced stopping power for normal stops and causes jerky stops
Solution Approach 1:
The braking torque is made dynamically adjustable through a control system that varies the engagement force of the friction pads based on operating conditions. The controller adjusts the braking torque between a first level for normal stops and a second level for emergency stops, enabling smooth stops during normal operation while maintaining reliable emergency stop capability when needed.
2Reliability
If a bulky heavy duty braking system is installed to handle emergency stops, then the brake can provide sufficient braking torque for emergency stops, but the brake cannot provide differentiated stopping power for normal versus emergency situations
Solution Approach 1:
The system dynamically adjusts braking torque based on operational mode. During normal operation, the controller maintains a first braking torque level that provides smooth stops. During emergency situations, the controller increases to a second, higher braking torque level. This dynamic adjustment enables a single braking system to adapt to different operational requirements without requiring separate systems for normal and emergency stopping.
Solution Approach 2:
The braking torque parameter is changed based on operational conditions. The controller modifies the engagement force of the friction pads, thereby changing the braking torque from a fixed value to a variable parameter. This allows the system to provide differentiated braking torque for normal versus emergency stops using the same physical brake components.
3Device complexity
If clutch-type brakes are used with fixed mechanical limits, then the brake structure remains simple, but the range of braking torque is narrow and cannot accommodate different stopping requirements
Solution Approach 1:
The braking system transitions from a static mechanical limit to a dynamic controllable parameter. The controller adjusts the engagement force of the friction pads in real-time, enabling the braking torque to vary within a wider range while maintaining a relatively simple brake structure. This dynamic control expands the effective braking torque range without requiring complex mechanical adjustments.
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
Enables smooth and controlled emergency stops without straining the system and reduces the need for bulky braking systems by combining counter EMF with frictional engagement for precise torque control.
Implementation Method 1
A braking device that utilizes counter-electromotive force (counter EMF) generated by a motor to provide a controlled braking torque
Implementation Method 2
engaging it frictionally once the counter EMF dissipates, allowing for smooth and controlled stops
Data Source
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AI summary
A braking device (140) for an elevator (20) is disclosed. The device (140) may include a motor (36), a braking system (52), a first switch (148), and a second switch (150). The motor (36) may be capable of generating a counter-electromotive force. The braking system (52) may move to a disengaged position upon being energized and may move to an engaged position upon being de-energized. The first and second switches (148, 150) may have an open state. In the open state, the switches (148, 150) electrically couple the motor (36) to the braking system (52) so that the counter-electromotive force of the motor (36) may energize the braking system (52).