Escalator Overspeed Prevention Device with Tension Spring Pawl
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Solution Overview
Problem
Existing overspeed and reverse drive preventing devices for escalators face issues with reduced braking power due to installation errors, limited movement of components, and increased installation time and costs, as well as potential damage to the escalator and support frame from perforation, especially when dealing with high loads and increased floor heights.
Innovation Solution
The proposed device incorporates a tension spring and ball joint to ensure the pawl is fully inserted into the ratchet, and additional braking members on the inner and outer peripheral surfaces to enhance braking power, while eliminating the need for perforation, thus preventing overspeed and reverse rotation effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional reverse rotation preventing apparatus is used, then the structure is simple, but the braking power is insufficient under high loads and installation errors reduce reliability
Solution Approach 1:
The patent combines multiple braking functions into a single integrated device. The rotation limiting part integrates both the pawl-ratchet mechanism for reverse rotation prevention and the brake lining for overspeed control, eliminating the need for separate braking devices and improving reliability without proportionally increasing complexity
Solution Approach 2:
The patent adds a radial dimension to the braking mechanism by mounting brake linings on both the inner and outer peripheral surfaces of the rotary shaft. This multi-dimensional approach distributes braking force across multiple contact points, significantly enhancing braking power while maintaining a compact structure
2Reliability
If the pawl rotation angle is limited due to installation errors, then the device is easier to install, but the pawl cannot be fully inserted into the ratchet reducing braking power
Solution Approach 1:
The patent employs a tension spring that dynamically adjusts the pawl's rotational position based on operational conditions. The spring's elastic deformation compensates for installation errors and ensures the pawl achieves full insertion into the ratchet teeth, maintaining reliable engagement despite variations in installation precision
Solution Approach 2:
The connection part is designed as a dynamic element that can rotate and deform under tension from the spring. This dynamic capability allows the system to self-adjust during operation, ensuring proper pawl engagement without requiring extremely tight installation tolerances
3Strength
If perforation is used to install the device, then the mounting is more secure, but the escalator and support frame may be damaged
Solution Approach 1:
The patent introduces a support part as an intermediary component that distributes mounting forces across a larger area of the support frame. This intermediary structure provides secure attachment without concentrating stress at single perforation points, preventing damage to the escalator components while maintaining firm installation
4Reliability
If additional braking members are added to enhance braking power, then the overspeed prevention is improved, but the device complexity increases
Solution Approach 1:
The patent merges the overspeed braking function with the existing rotation limiting structure. Brake linings are mounted on the peripheral surfaces of the same rotary shaft that houses the pawl-ratchet mechanism, combining two safety functions into one integrated assembly and avoiding the need for entirely separate braking systems
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 provides enhanced braking power, reduces installation time and costs, and prevents damage to the escalator and support frame by ensuring complete pawl insertion and distributing braking force effectively, even under high loads and varying conditions.
Implementation Method 1
a tension spring and ball joint to ensure the pawl is fully inserted into the ratchet
Implementation Method 2
additional braking members on the inner and outer peripheral surfaces to enhance braking power
Data Source
AI summary
The present invention relates to an overspeed and reverse drive preventing device for an escalator. The device has a pawl and a connection part mounted to be connected by a tension spring such that, when the pawl is inserted into gears of the ratchet and is compressed by a ratchet, the tension spring is extended and the pawl is perfectly inserted into the ratchet, thereby making it possible to apply the same to escalators having various specifications. A braking member is mounted on the inner peripheral surface of a brake arm mounted outside a ratchet part or a rotary shaft, or on the outer peripheral surface of the device facing the brake arm. Therefore, the overspeed and reverse drive preventing device can apply additional braking power to the escalator rotary shaft to prevent a damage of a brake lining mounted on the ratchet part, prevent overspeed or reverse rotation of the escalator even though the brake lining is damage so as not to show the braking power, and reduce installation expenses and period of time and prevent deterioration in durability caused by perforation work since there is no need to perform perforation work to the escalator rotary shaft and the escalator support frame.