Elevator Fall Arrest Device with Spring-Loaded Toothed Cleat
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Solution Overview
Problem
Existing elevator safety devices fail to prevent the fall of an elevator during negative telescoping, as they are designed to stop ascent but not descent, and existing braking systems can only slow down the elevator, not stop it completely.
Innovation Solution
A fall arrest device with a frame, lever, roller, cleat, and shock absorbers that can transition from a non-engaged to an engaged configuration to limit the descent of the elevator by rolling on a smooth rack face and engaging with a toothed rack, using a compression spring and unlocking mechanism to manage the engagement and disengagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If existing braking systems are used to slow down an elevator during descent, then the elevator speed can be reduced, but the elevator cannot be stopped completely and a fall remains possible
Solution Approach 1:
The invention changes the functional parameter of the safety device from speed reduction (braking) to complete stop (arrest). The fall arrest device uses a toothed cleat that engages with the rack to transform the continuous descent motion into a complete stop, fundamentally changing the parameter of motion control from speed modulation to motion arrest.
Solution Approach 2:
The safety function is segmented into two distinct components: a braking system for speed reduction and a fall arrest device for complete stop. The fall arrest device includes separate elements (roller, cleat, spring, shock absorber) that work together to provide the arrest function, dividing the safety function into modular segments that address different aspects of descent control.
2Reliability
If existing safety devices designed for upward movement are used, then ascent can be stopped, but they cannot prevent fall during downward movement
Solution Approach 1:
The invention inverts the design approach of traditional safety devices. Instead of designing a device that prevents upward movement (as in traditional overspeed governors), the fall arrest device is specifically designed to engage during downward movement. The toothed cleat and spring mechanism are configured to activate during descent, applying braking force in the opposite direction to traditional safety devices.
Solution Approach 2:
The fall arrest device integrates multiple functions into a single system: it provides mechanical engagement with the rack, stores energy via spring compression, absorbs impact through shock absorbers, and enables controlled engagement and disengagement. This multi-functional design makes the device adaptable to various operational scenarios during both ascent and descent.
3Reliability
If a mechanical stop is installed to limit downward travel, then fall can be prevented, but the stop must be removed during mast telescoping operations
Solution Approach 1:
The fall arrest device is self-activating and does not require manual installation or removal like fixed mechanical stops. The device automatically engages when needed through its spring-loaded mechanism and automatically disengages when the elevator reaches a safe position, eliminating the need for human intervention during mast telescoping operations while maintaining continuous fall protection.
Solution Approach 2:
The fall arrest device transitions from a static mechanical stop to a dynamic, movable system. The cleat and roller assembly can move along the rack, engaging and disengaging automatically based on operational conditions. This dynamic behavior allows the device to provide protection during normal operation and seamlessly recede during mast telescoping without requiring manual removal.
4Reliability
If a fall arrest device with engagement mechanism is implemented, then complete stop during descent is achieved, but the device complexity increases
Solution Approach 1:
The invention merges multiple safety functions into a single integrated device: the roller provides rolling contact with the rack, the toothed cleat provides mechanical engagement, the spring provides engagement force and energy storage, and the shock absorber provides impact mitigation. By combining these elements into one fall arrest device, the patent achieves comprehensive fall protection without requiring multiple separate systems, thereby reducing overall system complexity.
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
Effectively prevents the fall of the elevator by limiting its descent and allowing it to come to a complete stop, even in the absence of a lower mechanical stop, ensuring safety during mast telescoping operations.
Implementation Method 1
a roller (32) able to roll on a smooth face (220) of the rack
Implementation Method 2
said stop (33) being connected to the frame (30) by means of a compression spring (330)
Implementation Method 3
at least one shock absorber (34) disposed on an upper part of said fall arrest device (3)
Implementation Method 4
said stop (33) having a toothed portion (334) adapted to cooperate with a toothed face (221) of the rack (22)
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
The invention concerns a fall-prevention device for an elevator capable of being moved along a rack of an elevator mast, the fall-prevention device being characterised in that it comprises a frame (30), a lever (31), a roller (32) pivotally connected with the lever and attached to a first end of the lever, the roller being capable of rolling on a smooth side of the rack, a stop (33) attached to a second end of the lever, the stop comprising a toothed portion (334) capable of cooperating with a toothed face (221) of the rack and being connected to the frame by means of a compression spring (330), and at least one damper (34) arranged on a top portion of the fall-prevention device, the fall-prevention device being moreover characterised in that it is slidingly connected with the elevator.