Counterweight Safety Brake Linkage for Overspeed Force Relief
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Solution Overview
Problem
Existing slack-rope safety systems for elevator counterweights face challenges in managing excessive forces during overspeed events, leading to high component stress and potential system failure, and require robust and costly actuation modules or manual resets.
Innovation Solution
A counterweight safety system with a hinged link configuration between the sheave and safety brakes, incorporating multiple link members and biasing elements to distribute forces, reducing extreme loads and enabling controlled braking and easy resets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional governor-and-tension device system is used for counterweight safety actuation, then the system can detect overspeed events, but the components are subjected to excessive forces during overspeed events leading to high stress and potential failure
Solution Approach 1:
The connecting link is divided into multiple link members (first link member, second link member, third link member) connected through pivots. This segmentation distributes the excessive forces during overspeed events across multiple components and connection points, preventing any single component from bearing the full load and reducing the risk of catastrophic failure.
Solution Approach 2:
The link members are configured to move relative to each other through pivots during overspeed events, allowing the mechanism to dynamically adapt to extreme forces. The link members can change their spatial arrangement to accommodate the sudden movement, transforming rigid force transmission into a more flexible force distribution system that protects components from excessive stress.
2Strength
If robust actuation modules are used to handle excessive forces, then component strength is improved, but device complexity and cost increase
Solution Approach 1:
The safety actuation mechanism is self-actuating through the mechanical linkage of link members. When overspeed occurs, the tension member slackens and the link members automatically move to engage the safety brake without requiring external power or complex control systems. The gravity and inertia of the counterweight itself provide the actuation force, eliminating the need for additional motors, sensors, or control electronics.
Solution Approach 2:
The link members act as intermediaries between the tension member and the safety brake. Instead of directly connecting these components, the multi-segmented link mechanism mediates the force transmission, allowing controlled movement and force distribution while protecting both the tension member and brake from excessive forces.
3Device complexity
If manual resets are required after safety activation, then system simplicity is maintained, but ease of operation and productivity decrease
Solution Approach 1:
The safety mechanism automatically resets when the underlying issue is resolved. As the counterweight returns to its normal position and tension is restored in the tension member, the link members automatically return to their original configuration, disengaging the safety brake without requiring manual intervention. This self-resetting capability eliminates the need for manual reset operations while maintaining system simplicity.
4Manufacturing precision
If the connecting link uses a rigid structure, then manufacturing precision is improved, but the system cannot accommodate excessive forces during overspeed events
Solution Approach 1:
The rigid connecting link is segmented into multiple link members that can move relative to each other. This allows the system to maintain precise manufacturing tolerances for each individual component while gaining the flexibility needed to handle extreme forces. Each link member can be manufactured with high precision, and their coordinated movement provides the necessary compliance during overspeed events.
Solution Approach 2:
The link members transition from a static rigid structure to a dynamic articulated mechanism. During normal operation, the link members maintain stable positions providing precise force transmission. During overspeed events, they can dynamically adjust their configuration to accommodate extreme forces, combining manufacturing precision with operational flexibility.
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 system minimizes extreme forces on components, extends their lifespan, and allows for efficient, automated resets, enhancing the reliability and efficiency of elevator safety systems.
Implementation Method 1
a biasing element arranged to apply a force to urge the connecting link toward the disengaged position
Implementation Method 2
A sheave is mounted to an upper frame member of the frame and operably connects the counterweight to one or more tension members of the elevator system
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
Counterweights for elevator systems are described. The counterweights include a frame and a counterweight safety system attached to the frame. The safety system includes a safety brake mounted to an upright of the frame and configured to enable engagement with a guide rail to apply a braking force. A sheave is mounted to the frame and configured to operably connect to tension members. The sheave is configured to move between a first position when under tension and a second position when the tension is lost. A connecting link operably connects the sheave to the safety brake. The connecting link has first and second link members operably connected between the sheave and the safety brake.