Sash Bolt Locking Fitting with Dynamic Pivot Linkage
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Solution Overview
Problem
Existing espagnolette-lock type locking fittings face issues with torque arm being low at the start of locking, requiring high forces to overcome resistance, and limited vertical displacement of operating rods, leading to incomplete locking and difficulty in unlocking due to excessive frictional forces.
Innovation Solution
Incorporating a connecting rod with a pivot that moves in vertical translation, allowing for an instantaneous axis of rotation, and using a ramp to compensate for frictional forces during unlocking, ensuring complete locking and easy operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the distance between pivot axes of the rod and deadbolt is increased to improve torque arm, then the torque arm becomes high, but the forces transmitted to the deadbolt become excessive at the start of locking when torque arm is low
Solution Approach 1:
The connecting rod is designed with a pivot that moves vertically during operation, transforming from a fixed pivot to a dynamic pivot. This allows the instantaneous axis of rotation to change position, optimizing the torque arm at different stages of the locking cycle. At the start of locking, the pivot position provides an optimal torque arm without excessive force transmission, while at the end of locking, the pivot moves to provide the necessary mechanical advantage.
Solution Approach 2:
The pivot is introduced in a vertical dimension between the horizontal articulation axes of the connecting rod and deadbolt. This vertical dimension allows the pivot to move independently in the vertical direction while maintaining horizontal articulation, creating a three-dimensional linkage that optimizes torque transmission at different positions in the locking cycle.
2Force
If the connecting rod is lengthened to overcome low torque arm at start of locking, then the torque arm is improved, but the size of the locking fitting control mechanism increases
Solution Approach 1:
Instead of using a longer static connecting rod, the invention uses a shorter rod with a dynamic pivot that moves vertically. This dynamic pivot creates the necessary torque arm variation without requiring excessive rod length, thereby keeping the control mechanism compact while still providing sufficient torque at the start of locking.
Solution Approach 2:
The pivot is pre-positioned in the housing at a specific location that optimizes the torque arm at the critical moment of locking initiation. This preliminary positioning of the pivot allows the connecting rod to achieve optimal mechanical advantage without requiring excessive length, as the pivot is already in the correct position to provide the necessary torque.
3Device complexity
If the vertical displacement amplitude of the operating rod is limited, then the mechanism size is reduced, but the locking members do not completely reach their locking position in the striker plate
Solution Approach 1:
The pivot moves vertically during the locking operation, dynamically changing the geometry of the connecting rod linkage. This vertical movement of the pivot amplifies the vertical displacement of the operating rod at the end of the locking stroke, ensuring complete engagement of the locking members with the striker plate without requiring excessive overall mechanism size.
Solution Approach 2:
The vertical movement of the pivot in the vertical dimension creates an additional degree of freedom that amplifies the displacement of the operating rod. This vertical dimension allows the connecting rod to convert horizontal motion into enhanced vertical motion, ensuring complete locking engagement while keeping the overall mechanism compact.
4Device complexity
If frictional forces are not compensated during unlocking, then the mechanism is simpler, but excessive frictional forces make unlocking difficult
Solution Approach 1:
The horizontal component of the force exerted by the control member on the connecting rod, which would normally create harmful frictional forces in the pivot guide, is converted into a beneficial effect. The ramp is designed to utilize this horizontal component to generate a counteracting force that compensates for the friction, transforming the potentially harmful friction into a manageable and even beneficial force that aids in unlocking.
Solution Approach 2:
The ramp acts as an intermediary element between the horizontal force component and the frictional forces in the pivot guide. It translates the horizontal force into a vertical counteracting force through its geometric configuration, mediating the interaction between the control member and the pivot guide to compensate for friction without adding complex active control mechanisms.
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 locking efficiency by providing additional movement at the end of locking and reduces the effort required for unlocking by compensating frictional forces, ensuring secure engagement and disengagement of locking members.
Implementation Method 1
the connecting rod comprises a pivot with an axis parallel to the articulation axes movable in a guided manner in vertical translation in said housing in order to define an instantaneous axis of rotation around which is pivoted, for driving the operating rod of the easel, the second axis of articulation of said connecting rod
Implementation Method 2
the action of the control member, for example the deadbolt, on the connecting rod has the consequence of imparting to the pivot, guided in vertical translation in the housing, a force breaking down into a vertical and horizontal component. This horizontal component generates, through the guide by the casing, a reactive force, from which result frictional forces capable of opposing the vertical displacement of the pivot
Data Source
Figure 1~6
Figure 2~3
AI summary
The fitting has a control mechanism (4) acting on a control part (8) such that a latch bolt (9) is displaced in a case (5). The mechanism has a transmission unit (10) in the form of a connecting rod ensuring a vertical displacement of a positioning bar (6) or stud due to the horizontal displacement of the control part. The rod is integrated to the control part and the bar using two hinges (12, 13), respectively. The rod has a pivot (14), between the hinges, movably mounted in the case for defining an instantaneous rotation axis around which an axle of the hinge (13) pivots for driving the bar.