Elevator Overspeed Governor With Nonlinear Resistance Staging
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Solution Overview
Problem
Existing overspeed governors for elevators exhibit a negligible time gap between a no-failure and failure situation due to linear increase in spring and centrifugal forces, lacking versatility and ease of adaptation to different requirements.
Innovation Solution
An overspeed governor with a sheave, cam, pendulum member, and additional resisting elements that modulate resistance forces non-linearly, featuring a cam follower wheel that loses contact at specific speeds and engages notches at higher speeds, with adjustable mechanical stoppers and springs to set desired resistance levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If linear spring force and centrifugal force are used in the governor, then the结构简单 (structure is simple), but the time gap between no-failure and failure situations becomes negligible
Solution Approach 1:
The patent applies parameter changes by introducing a non-linear resistance characteristic through the cam profile design. The cam profile is specifically shaped to create a non-linear relationship between rotational speed and resisting force, transforming the linear force characteristics into non-linear ones. This allows the governor to provide adequate response time while maintaining structural simplicity.
Solution Approach 2:
The cam profile utilizes curvature to achieve non-linear force characteristics. By designing the cam with specific curved surfaces, the patent transforms the linear centrifugal force and spring force relationship into a non-linear one, enabling controlled acceleration phases that provide sufficient safety response time without complicating the overall structure.
2Reliability
If non-linear resistance forces are introduced, then safety and versatility are enhanced, but device complexity increases
Solution Approach 1:
The cam component serves multiple functions: it generates non-linear resistance forces, provides adjustable contact characteristics through its profile design, and enables versatile adaptation to different elevator systems. By making the cam multi-functional, the patent achieves enhanced safety and versatility without proportionally increasing device complexity.
Solution Approach 2:
The cam acts as an intermediary element that translates rotational speed variations into non-linear resistance forces. This mediator component simplifies the overall system by concentrating the non-linear force generation function in a single element, rather than requiring complex multi-component resistance modulation mechanisms.
3Speed
If the cam follower wheel loses contact with the cam at specific speeds, then rapid response to overspeed conditions is ensured, but manufacturing precision requirements increase
Solution Approach 1:
The cam profile is pre-designed to anticipate overspeed conditions by incorporating specific geometric features that automatically cause the follower wheel to lose contact at predetermined speeds. This preliminary design approach ensures rapid response to overspeed without requiring real-time control adjustments, thereby reducing manufacturing precision requirements compared to active control 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
Enhances safety and versatility by providing adjustable resistance forces, ensuring rapid response to overspeed conditions and easy adaptation to various elevator systems.
Implementation Method 1
The cam having a profile such that for rotation speeds of the sheave greater than a first rotation speed, the cam follower wheel momentarily loses contact with the cam at intervals
Implementation Method 2
a main resisting element mounted between the frame and the pendulum member... at least one additional resisting element which is configured to be active on the pendulum member starting from a third rotation speed
Data Source
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AI summary
Overspeed governor (1) for an elevator, comprising: a sheave (2) and a cam (4) mounted on a side so as to rotate with the sheave (2); a pendulum member (5) mounted on the frame (25) so to rotate around a pivotal point (6) and provided with a tripping pawl (8); a cam follower wheel (3) mounted on the pendulum member (5) to follow the profile of the cam (4) when the sheave (2) is rotating and for rotation speeds of the sheave (2) greater than a first rotation speed, the cam follower wheel (3) starts leaping at intervals; a plurality of engaging portions (9) arranged on a side of the sheave (2) so as to rotate with the sheave (2), the engaging portions (9) and the pendulum member (5) being arranged so that at reaching of a second rotation speed of the sheave (2), the tripping pawl (8) engages one of the engaging portions (9); a main resisting element (23) mounted between the frame (25) and the pendulum member (5); at least one additional resisting element (12) which starts to act on the pendulum member (5) from a third intermediate rotation speed of the sheave (2).