Elevator Brake Redundancy With Three Plungers and Two Discs
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Solution Overview
Problem
Elevator brakes with two brake discs and two plungers can cause hard stops when one plunger malfunctions, compromising safety and passenger comfort.
Innovation Solution
An elevator brake system with three movable plungers and two brake discs, utilizing serially arranged springs and solenoids to ensure redundancy and independent engagement with brake discs, preventing hard stops even in malfunction scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two brake discs and two plungers are used to enhance safety redundancy, then reliability is improved, but hard stops occur when both plungers engage simultaneously due to loss of electric power
Solution Approach 1:
The brake system is segmented into two independent braking circuits, each with its own plunger and spring. The first plunger engages the first brake disc while the second plunger engages the second brake disc. This segmentation ensures that if one circuit fails or engages unintentionally, the other circuit can compensate, preventing hard stops while maintaining safety redundancy.
Solution Approach 2:
Springs are pre-loaded to provide a cushioning effect during plunger engagement. The first spring is pre-loaded to engage the first plunger, and the second spring is pre-loaded to engage the second plunger. This beforehand cushioning ensures smooth engagement and prevents sudden hard stops, while the pre-loaded springs provide the necessary braking force for safety redundancy.
2Force
If two plungers are moved into frictional engagement with brake discs during power loss, then braking force is sufficient to stop the elevator car, but passenger comfort deteriorates due to hard stops
Solution Approach 1:
The braking force is segmented and distributed across two independent circuits. Each plunger-spring-brake disc assembly provides a portion of the total braking force. During power loss, both plungers engage their respective brake discs simultaneously, distributing the braking force smoothly rather than concentrating it in one location, thereby maintaining passenger comfort while achieving sufficient stopping force.
Solution Approach 2:
The springs are pre-loaded to provide a cushioning effect that modulates the braking force application. This beforehand cushioning ensures that the braking force is applied gradually and smoothly, preventing sudden jerks or hard stops that would compromise passenger comfort, while still delivering sufficient total braking force to stop the elevator car safely.
3Reliability
If multiple plungers are used to prevent malfunction, then reliability is enhanced, but device complexity increases
Solution Approach 1:
The brake system is divided into two identical, independent circuits, each consisting of a plunger, spring, and brake disc assembly. This segmentation provides redundancy and malfunction prevention while maintaining a relatively simple structure through repetition of proven components. The modular nature of the segmented design makes maintenance and replacement straightforward, offsetting the increased complexity.
Solution Approach 2:
Both plungers and both brake discs are designed with universal functionality to perform the same braking operation. This multi-functionality allows the system to maintain reliability through redundancy while using standardized components that simplify manufacturing, assembly, and maintenance. The universal design reduces the need for specialized parts, thereby managing device complexity despite the increased number of 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
Ensures reliable braking without hard stops, enhancing safety and extending brake disc lifetime by allowing independent plunger engagement and reducing wear on brake linings.
Implementation Method 1
Each of the at least two springs is configured for applying a spring force to at least two of the at least three movable plungers for urging the at least one movable plunger towards at least one of the brake discs
Implementation Method 2
Each of the at least two solenoids is associated with a respective one of the at least two springs and configured for producing a counterforce directed against the respective spring force applied by the respectively associated spring
Implementation Method 3
at least one plunger that is movable into frictional engagement with the brake disc for braking and stopping any rotation of the brake disc
Data Source
AI summary
An elevator brake for braking rotation of a shaft in an elevator drive system comprises at least two brake discs mounted to the shaft Such as to rotate concurrently with the shaft; at least three movable plungers, which are movable along the axial direction (A) for selectively engaging or releasing the elevator brake; and an actuator. The actuator comprises at least two springs configured for applying a spring force to at least one of the at least three movable plungers for urging the at least one movable plunger towards at least one of the brake discs for engaging the elevator brake; and at least two solenoids for producing a counterforce directed against the respective spring force applied by a respectively associated spring such as to urge the respective at least one movable plunger in the axial direction (A) away from the respective brake disc.