Espagnolette Lock Coupling Pawl Force Transmission
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Solution Overview
Problem
Existing espagnolette locks require high strength and large installation space due to the force transmission through the clutch pawl, which is inefficient and not suitable for external doors without a deadbolt and espagnolette connection slide.
Innovation Solution
The design features a coupling pawl with greater play in its mounting than in the clutch projection, allowing power flow between coupling projections and only stressing the coupling pawl's area between projections, enabling a compact and strong structure with reduced force transmission through the mounting, and a simplified power transmission path with a bearing axis and arm supporting the projections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the coupling pawl is designed with a bearing for mounting on the latch retraction lever, then the latch can be pulled back via the handle, but the entire coupling pawl becomes loaded requiring high strength and large installation space
Solution Approach 1:
The invention extracts the force transmission function from the mounting bearing by designing the play in mounting to be greater than the play in the coupling projection. This prevents forces from being transmitted via the mounting, isolating the bearing from load and allowing the coupling pawl to be smaller and lighter while maintaining operational capability.
2Ease of operation
If the coupling pawl is designed with a bearing for mounting, then the latch can be pulled back, but the installation space required increases
Solution Approach 1:
The invention removes the load transmission function from the mounting bearing through the play design, allowing the coupling pawl to be minimized in size. This extraction of the force transmission path enables compact dimensions suitable for external doors while preserving the latch retraction function.
3Ease of operation
If forces are transmitted through the mounting of the coupling pawl, then the latch can be actuated, but static overdetermination occurs and forces are transmitted via the mounting
Solution Approach 1:
The invention extracts the force transmission path from the mounting by designing play in mounting greater than play in the coupling projection. This prevents static overdetermination and ensures forces are transmitted only through the coupling projections, improving reliability by eliminating uncertain force paths through the mounting.
Data Source
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AI summary
In a rod lock (4) for a double-leaf door, a coupling latch (20) has two coupling projections (22, 30) to create a positive fit between a cam half (15) and a latch release lever (18). One of the coupling projections (22) creates a positive fit with the cam half (15), while the other coupling projection (30) creates the positive fit with the latch release lever (18). A bearing (29) of the coupling latch (20) is thus not subjected to any load during force transmission between the cam half (15) and the latch release lever (18).