Elevator Hoistway Spacing via Counterweight Buffer Strokes
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Solution Overview
Problem
Existing elevator systems with multiple cars in a hoistway face challenges in preventing collisions between cars and efficiently using hoistway space without requiring special modifications or excessive additional space.
Innovation Solution
The solution involves strategically selecting the lengths of load bearing members and considering counterweight buffer strokes and dynamic jumps to maintain spacing between elevator cars, using different roping ratios for load bearing members, and incorporating passages within the elevator car to optimize space usage and prevent car contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple elevator cars are placed in a single hoistway to improve passenger service, then productivity is improved, but the risk of collision between cars increases and space arrangement becomes more complex
Solution Approach 1:
The patent applies preliminary action by pre-configuring the load bearing members with specific lengths and roping ratios before operation. The counterweights are positioned at predetermined locations along the hoistway, and the load bearing members are tensioned to establish fixed geometric relationships. This preliminary arrangement ensures that during normal operation and even during buffer strokes, the cars cannot collide because the counterweights physically block their paths before collision could occur.
Solution Approach 2:
The patent uses counterweights as intermediary elements between the elevator cars. The counterweights serve as mediators that prevent direct contact between cars by occupying the space between them. When a car moves toward another car, its counterweight moves in the opposite direction and can contact the other counterweight or the other car's counterweight, thereby preventing car-to-car collision through this intermediary mechanism.
2Reliability
If load bearing members are arranged to prevent car contact, then reliability is improved, but hoistway space consumption increases
Solution Approach 1:
The patent merges the functions of multiple components into a compact arrangement. The load bearing members are routed through passages in the counterweights and cars, combining the structural support function with the space-defining function. The counterweights serve dual purposes: they provide counterbalancing force and simultaneously define the maximum travel limits of the cars. This merging eliminates the need for separate collision prevention mechanisms, optimizing hoistway space usage.
Solution Approach 2:
The patent utilizes the vertical dimension of the hoistway efficiently by arranging counterweights at different elevations along the hoistway. The load bearing members are routed through the counterweights in a three-dimensional configuration, allowing the system to prevent collisions by utilizing vertical spacing rather than requiring additional horizontal space. This dimensional arrangement allows compact packaging of the multiple car system.
3Reliability
If load bearing members are made longer to accommodate counterweight buffer strokes and dynamic jumps, then reliability is improved, but the complexity of arranging components increases
Solution Approach 1:
The patent applies parameter changes by varying the roping ratios of different load bearing members. Some load bearing members have a 1:1 roping ratio while others have a 2:1 roping ratio. This parameter variation allows the system to accommodate different buffer stroke requirements and dynamic jump characteristics of different cars. By changing the roping ratio parameter, the system can maintain proper spacing and tension without requiring complex adjustable mechanisms, thereby reducing overall system complexity while maintaining reliability.
Data Source
AI summary
An elevator system (20) includes multiple elevator cars (22, 32) within a hoistway (26). Counterweights (24, 34) are associated with the respective elevator cars (22, 32) by load bearing members (40, 50). In some examples, different roping ratios are used for the load bearing members (40, 50). In some examples, the lengths of the load bearing members (40, 50) are selected to allow contact between the counterweights (24, 34) within the hoistway (26) and prevent contact between the elevator cars (22, 32). The difference in car and counterweight separation distances is greater than a stroke of a counterweight buffer plus an expected dynamic jump of the elevator cars. A disclosed example includes passages (80) through a portion of at least one of the elevator cars (22) for accommodating the load bearing member (50) of another elevator car (32) located beneath the elevator car (22) with the passages (80).