Transit Door Isolation Lock Linkage Assembly
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current door operator systems for transit vehicles require a high actuation force to disengage isolation locks when using the emergency release, which can be cumbersome and inefficient, especially when compatibility with standards like the North American APTA Standard PR-M-S-18-10 is considered.
Innovation Solution
A door operator system with an emergency release device and isolation lock mechanism that includes a linkage assembly connected to the emergency release device, allowing it to move a lock pin from an engaged to a disengaged position, reducing the required actuation force and ensuring compliance with standards by integrating with overcenter locking mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a traditional isolation lock mechanism is used with emergency release, then the door can be locked securely during maintenance, but the actuation force required to disengage the lock exceeds the maximum allowable pull force specified in standards
Solution Approach 1:
The lock mechanism is divided into two independent locking elements: an overcenter lock for primary door securing and a separate isolation lock for maintenance isolation. This segmentation allows the emergency release to selectively disengage only the isolation lock with low force, while the overcenter lock provides robust primary locking that doesn't interfere with emergency operation.
Solution Approach 2:
A linkage assembly acts as an intermediary mechanism between the emergency release device and the isolation lock. This linkage translates the low-force emergency release pull into sufficient motion to disengage the isolation lock, while being decoupled from the high-force overcenter locking mechanism.
2Adaptability or versatility
If the emergency release is designed to disengage the isolation lock, then compliance with standards is achieved, but the complexity of the mechanism increases
Solution Approach 1:
The isolation lock mechanism is designed to perform multiple functions: it provides maintenance isolation capability, complies with emergency release standards, and integrates seamlessly with the existing overcenter door operator system. The same basic linkage structure serves both normal operation and emergency release functions.
Solution Approach 2:
The isolation lock mechanism is nested within the existing door operator system, utilizing the available space and structural elements. The linkage assembly is integrated into the door operator housing, and the isolation lock components are positioned within the existing mechanical envelope, avoiding additional external complexity.
3Strength
If a robust locking mechanism is used to ensure door security, then the door remains securely locked, but the actuation force required exceeds standard limits
Solution Approach 1:
The locking function is segmented between two mechanisms: the overcenter lock provides strong primary locking for normal door operation, while the separate isolation lock handles maintenance isolation. This segmentation allows each mechanism to be optimized for its specific function without compromising the other.
Solution Approach 2:
The emergency release is designed to perform only the partial action of disengaging the isolation lock, not the full locking function. This partial action requires minimal force and satisfies the standard's pull force requirements while maintaining overall door security through the separate overcenter locking mechanism.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An isolation lock mechanism (30) for a transit vehicle door includes a lock bracket (31) configured to be connected to the transit vehicle door; a lock pin (33) configured to be moved between an engaged position in which the lock pin (33) is extended to engage the lock bracket (31) and a disengaged position in which the lock pin (33) is withdrawn from the lock bracket (31); and a linkage assembly connected to the lock pin (33) and configured to be actuated to move the lock pin (33) between the engaged position and the disengaged position. The linkage assembly is configured to be connected to an emergency release device such that operation of the emergency release device to unlock the transit vehicle door also actuates the linkage assembly to move the lock pin (33) from the engaged position to the disengaged position.