Spiral Lock Follower Spring for Door Lock Play Elimination
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Solution Overview
Problem
Conventional door locks with square lock pins and followers experience play and wear issues, leading to increased installation difficulty and reduced torque application efficiency, as the square design inevitably results in wobbling and increased play over time.
Innovation Solution
A door lock design featuring a spirally wound lock follower spring with a retaining slot and two free ends, where one end is connected to the housing and the other applies torque to the lock pin, ensuring a secure, non-rotatable fit and easy installation by jamming the lock pin in place, preventing play and allowing direct torque application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tight fit between lock pin and lock nut is used to avoid play, then play is reduced, but installation becomes more difficult
Solution Approach 1:
The lock follower spring is segmented into two free ends with distinct functions: one end provides clamping force to eliminate play, while the other end applies torque to the lock pin. This segmentation allows the system to achieve both tight fixation and easy installation separately through different parts of the same component.
Solution Approach 2:
The lock follower spring is pre-loaded during assembly to automatically clamp the lock pin in place. The spiral windings are designed to exert preliminary clamping force that eliminates play before the lock pin is fully inserted, making installation easier while ensuring reliable play avoidance.
2Stability of the object's composition
If a square lock pin design is used to achieve form-fitting connection, then non-rotatable connection is achieved, but play and wear increase over time
Solution Approach 1:
The lock follower spring changes its physical state from a relaxed spiral to a compressed state during assembly, generating clamping force that reduces the clearance between the square lock pin and the opening. This parameter change (from relaxed to compressed) eliminates play while maintaining the non-rotatable connection.
Solution Approach 2:
The lock follower spring introduces asymmetric clamping force through its spiral winding configuration, applying pressure preferentially in directions that eliminate play between the square lock pin surfaces and the opening, thereby reducing wear on specific contact points.
3Ease of manufacture
If the lock pin wobbles in the opening, then installation is easier, but torque application efficiency is reduced
Solution Approach 1:
The lock follower spring transitions from a static relaxed state to a dynamic compressed state during lock pin insertion, automatically adjusting the clamping force to guide the lock pin into proper position. This dynamic behavior facilitates easy installation while ensuring subsequent torque application efficiency.
Solution Approach 2:
The lock follower spring acts as an intermediary element between the housing and the lock pin, mediating the interaction by providing both clamping force for stable positioning and torque application capability, thereby resolving the conflict between installation ease and torque efficiency.
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 eliminates play between the lock pin and follower, simplifies installation, and enables efficient torque transmission for latch movement, maintaining precision and functionality over time.
Implementation Method 1
a spirally wound lock follower spring is provided
Implementation Method 2
the lock follower spring thus acts not only as a movement spring for the pivoting movement of the lock follower, but also as a clamping spring for the lock pin
Data Source
Figure 1a~5b
Figure 6
AI summary
The door lock has a lock nut (2) comprising an opening which passes through lock nut over entire width. The cross-section of opening is slightly larger than cross section of a lock pin (1). The lock nut is provided with a driver shaft (9) which is engaged with a latch shaft connected to case of the door lock in the open or close position. A spiral wound follower spring is arranged such that one free end (6) of spring is connected to case and another free end (7) of spring is made to pass the inside of cross section of opening.