Elevator Free Fall Protection Without OSG Rope
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Solution Overview
Problem
Existing elevator free fall protection systems, particularly those using overspeed governors (OSG) ropes, face issues such as inertia-related unintended activation of safety gears, rope tangling due to building sway, and increased guide rail dimensions for safety gear gripping.
Innovation Solution
A novel free fall protection system that eliminates the OSG rope and safety gears by using a free fall protection member with a lower pre-tensioning load, supported by separate pulleys and brake devices, ensuring the car and counterweight are only fully supported by this system in case of hoisting member failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an OSG rope is used to connect the overspeed governor sheave and safety gear, then the safety gear can be activated in case of overspeed, but the inertia of the rotating parts and OSG rope may cause unintentional activation of the safety gear
Solution Approach 1:
The patent removes the OSG rope from the system entirely, replacing it with a direct mechanical connection between the overspeed governor sheave and safety gear. This extraction eliminates the source of inertia-related problems while maintaining the safety function.
Solution Approach 2:
The patent separates the overspeed detection function from the safety gear activation mechanism by using a direct rigid connection instead of a flexible rope, allowing independent optimization of each component's performance characteristics.
2Reliability
If an OSG rope is used in high-rise buildings, then the safety gear can be activated in case of overspeed, but the weight of the OSG rope becomes a significant problem
Solution Approach 1:
The patent eliminates the OSG rope entirely from the system, replacing it with a rigid mechanical connection. This extraction completely removes the weight issue associated with long OSG ropes in high-rise buildings while maintaining safety functionality.
3Reliability
If an OSG rope runs close to stationary structures in the shaft, then the safety gear can be activated in case of overspeed, but the OSG rope may become tangled in the shaft structures due to building sway
Solution Approach 1:
The patent removes the flexible OSG rope and replaces it with a rigid mechanical connection system that includes a tensioning device. This eliminates the tangling problem entirely as the rigid connection cannot become entangled with shaft structures.
Solution Approach 2:
The patent introduces a dynamic tensioning device that can adjust the connection between the overspeed governor sheave and safety gear, allowing the system to adapt to building sway and maintain proper positioning without tangling.
4Reliability
If safety gears are provided to grip the guide rails for free fall protection, then the car and counterweight can be protected in case of overspeed, but the guide rail dimensions must be increased to accommodate the safety gear gripping
Solution Approach 1:
The patent replaces the mechanical safety gear gripping system with an alternative free fall protection mechanism that does not require the safety gear to grip the guide rails, thereby allowing the use of smaller, more efficient guide rail dimensions.
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
This solution reduces the deceleration requirement to 0.5g, allowing for lighter guide rail construction, eliminating the risk of safety gear activation causing guide rail collapse, and enabling smoother operation without the need for additional lock-down apparatuses.
Implementation Method 1
a brake device (110, 120) arranged to act on the free fall protection member (100)
Implementation Method 2
a separate pulley (36) for the free fall protection member (100)
Data Source
Figure 1
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AI summary
The elevator comprises a car (10), a counterweight (41), and a hoisting member (42) connecting the car with the counterweight over a traction sheave (33). A free fall protection system comprises a free fall protection controller (200), a free fall protection member (100) connecting the car with the counterweight over the traction sheave or over a separate free fall sheave (36). The car and the counterweight are supported by the hoisting member in normal operation and by the free fall protection member only in a situation in which the hoisting member support fails. At least one free fall protection brake device (110, 120) is arranged to stop the movement of the free fall protection member and thereby also the movement of the car and/or the counterweight, when being activated by the free fall protection controller.