Elevator Park Brake Release for Smooth Car Movement
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Solution Overview
Problem
Elevator cars experience displacement issues when the park brake is opened due to unbalanced forces from rope tension and gravity, leading to uncomfortable drops or jumps, and existing solutions are inefficient in controlling compression members and maintaining structural simplicity and compactness.
Innovation Solution
A method and elevator system where the park brake's compression force is gradually reduced to allow the elevator car to move vertically, ensuring that forces counteract each other, using a screw jack and motor-controlled compression members to manage the force and movement smoothly, and sensors to monitor and control the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the park brake is opened quickly to release the elevator car, then the car can start moving, but the unbalanced forces cause the car to drop or jump creating uncomfortable sensations for passengers
Solution Approach 1:
The brake compression force is made dynamically adjustable during the movement process. The system transitions from a static high compression force (when parked) to a progressively reducing compression force, allowing the car to move smoothly while maintaining force balance. This dynamic adjustment prevents sudden drops or jumps by continuously adapting the compression force to the car's movement state.
Solution Approach 2:
The compression force parameter is changed progressively from high to low during the car's movement. By reducing the compression force in controlled steps rather than maintaining a constant high force, the system allows the car to accelerate smoothly while keeping the force balance between rope tension and gravity approximately equal, thereby eliminating passenger discomfort.
2Ease of operation
If the compression force of the park brake is reduced to allow car movement, then the car can move vertically, but controlling the back and forth movement of compression members becomes complex
Solution Approach 1:
The system uses the car's own movement state and force balance conditions to automatically control the compression force adjustment. The brake system responds to the natural equilibrium between rope tension and gravity, reducing compression force when the car tends to drop and increasing it when the car tends to rise, without requiring complex external control mechanisms.
Solution Approach 2:
The system incorporates feedback from the car's movement state and force balance conditions to adjust the compression force. By monitoring whether the car is tending to drop or rise, the system automatically adjusts the compression force accordingly, creating a self-regulating control mechanism that simplifies the overall control system.
3Stability of the object's composition
If the park brake uses high compression force to hold the car immovable, then the car remains stationary during loading, but the structure requires higher strength components
Solution Approach 1:
The compression force is made dynamic rather than static. During the parked state, high compression force maintains stability. During movement, the compression force is progressively reduced. This dynamic approach allows the system to achieve both stability when needed and reduced strength requirements during movement, as the high force is only applied when the car is stationary.
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 effectively prevents the feeling of drops or jumps when the park brake is opened by ensuring equilibrium forces, providing smooth and controlled movement, and maintaining structural efficiency and simplicity.
Implementation Method 1
The moving means comprises a screw jack operable to move, by screwing, the compression members towards each other
Implementation Method 2
The suspension ropes are elastic at least to some degree. If not prevented, this elasticity has the potential of causing problematic car displacement during loading and unloading
Implementation Method 3
a park brake for holding the elevator car immovable at a landing... compressing at least one guide rail by compression members of the at least one brake
Data Source
AI summary
A method for controlling movement of an elevator car includes driving the car vertically to a landing; activating a park brake; and holding the car immovable with the park brake. The holding includes compressing a guide rail by compression members with a first compression force; opening a door for allowing loading and/or unloading the car; maintaining the door open for allowing loading and/or unloading the car while the car is held immovable; and starting closing movement of the door. After the starting closing movement of the door, relieving the brake for allowing the elevator car to start to move vertically. The relieving includes reducing the compression force of the brake, to be smaller than the first compression force, such that the compression members start sliding vertically against the guide rail; maintaining compression with a smaller compression force than the first compression force, allowing the compression members to continue to slide vertically against the guide rail; and thereafter removing the compression.