Tool-Free Cam Adjustment for Lock Mechanisms
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Solution Overview
Problem
Conventional cam arrangements for locking mechanisms require specific tooling to adjust contact pressure between a window or door sash and its frame, making it difficult or impossible to adjust without such tooling.
Innovation Solution
A cam arrangement that is rotatable about an axis and features a retention mechanism, allowing the cam to be moved axially between two positions, enabling adjustment without tooling, with splines providing an interference fit for retaining the cam in desired angular positions, and a biasing member for automatic reset.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If specific tooling is used to adjust the cam position, then the contact pressure can be adjusted, but the ease of operation deteriorates because specific tooling is required
Solution Approach 1:
The cam arrangement enables self-adjustment by the user without requiring external tooling. The cam can be manually moved axially to disengage the retention mechanism and rotated to adjust the contact pressure, then automatically retained in position by the spring-loaded splined shaft.
Solution Approach 2:
The retention mechanism transitions from a static locked state to a dynamic adjustable state. The spring-loaded splines allow the cam to be moved axially when force is applied, disengaging the retention mechanism temporarily to permit rotation, then automatically return to the retained state when the adjusting force is removed.
2Adaptability or versatility
If the cam is made rotatable between multiple angular positions, then the adjustability improves, but the reliability deteriorates because the cam may inadvertently change position
Solution Approach 1:
The spring-loaded splined shaft provides continuous feedback and automatic retention. When the cam is rotated to a new angular position, the spring automatically engages the splines to lock the cam in place, providing tactile feedback to the user that the adjustment is secured. The spring constant is calibrated to provide sufficient retention force to prevent inadvertent movement while allowing intentional adjustment.
3Ease of operation
If the retention mechanism is always engaged, then the cam position is stable, but the ease of operation worsens because the cam cannot be adjusted
Solution Approach 1:
The retention mechanism operates periodically - engaged during normal operation to maintain stability, and temporarily disengaged during adjustment. The spring-loaded design allows the retention force to be periodically overcome by applying axial force to move the cam, then automatically re-engaged when the adjusting force is removed, creating a cycle of locked-stable and adjustable states.
Data Source
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AI summary
A cam arrangement 10 is provided for a lock mechanism 12 of a closure 50, e.g. a window or door closure. The cam arrangement 10 comprises a cam 14 rotatable about an axis between a plurality of angular positions; and a retention mechanism which, when engaged, retains the cam 14 in its current angular position. The cam 14 is moveable along the axis between a first axial position in which the retention mechanism is engaged and a second axial position in which the retention mechanism is disengaged. In this way, when the cam 14 is in its second axial position it may be rotated between the plurality of angular positions.