Dual Action Door Latch Assembly with Cam and Lever Bolt
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Solution Overview
Problem
Door latches designed for dual-sided operation often malfunction when doors made of materials like wood composite swell due to moisture, causing mechanical binding and requiring spring tension adjustments.
Innovation Solution
A dual-action latch design featuring a lever arm, elongate bolt, cam, and biasing device, allowing for both rotational and pull-based operation without needing spring tension adjustments, with a cam that impinges on the bolt to withdraw it into the housing and a lever arm that impinges on the bolt's recess to achieve this, accommodating door thickness changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a coil spring is used to accommodate door thickness changes, then the latch can adjust to swelling doors, but spring tension adjustments are required and the mechanism becomes more complex
Solution Approach 1:
The patent removes the coil spring from the mechanism entirely, replacing it with a cam and lever arm system. The cam profile is designed to provide the necessary mechanical advantage and movement range to accommodate door swelling without requiring any spring tension adjustments, thus extracting the problematic spring component while maintaining the adaptability function.
Solution Approach 2:
The cam acts as an intermediary element between the lever arm and the bolt. By designing the cam profile with specific geometric characteristics, it mediates the relationship between the lever arm movement and bolt retraction, providing the necessary accommodation for door thickness changes without the complexity of spring adjustments.
2Reliability
If both handles are operated by turning, then the latch provides consistent operation, but it limits the operational modes and requires spring tension adjustments
Solution Approach 1:
The latch mechanism is designed to accept multiple types of handle operations (turning, pushing, pulling, or lifting) through a universal interface. The cam and lever arm system can respond to various input motions and convert them into the required bolt retraction motion, making the latch universally compatible with different handle types and operational modes while maintaining reliable operation.
3Stability of the object's composition
If the door material swells due to moisture exposure, then the door becomes thicker over time, but this causes the mechanical connection between latch components to bind up
Solution Approach 1:
The cam and lever arm system provides dynamic adjustment capability that accommodates changing door thickness. As the door swells or shrinks, the cam profile allows the lever arm to move along its arc, automatically adjusting the mechanical connection geometry to maintain smooth operation without binding, thus adapting to the changing door composition while preserving operational ease.
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
Ensures consistent and reliable operation of door latches across varying door thicknesses without requiring initial spring tension adjustments, preventing binding issues and enhancing ease of operation from either side.
Implementation Method 1
a biasing device which biases the elongate bolt such that its distal end extends out of the open end of the latch housing
Implementation Method 2
when the cam is rotated the cam plate impinges on the elongate bolt and withdraws the elongate bolt into the latch housing
Implementation Method 3
when the latch handle is moved the lever arm impinges on the proximal end of the recess of the elongate bolt and withdraws the elongate bolt into the latch housing
Data Source
AI summary
A dual action latch, having a latch handle, an elongate bolt, a cam, a latch housing, and a biasing device, for installation on one side of door. The latch handle includes a lifting portion and a lever arm. The latch housing has a lever arm aperture through which the lever arm of the latch handle passes and a bolt guide for slidably receiving the elongate bolt. The latch handle is movably attached to the latch housing. With the latch handle moved, the lever arm withdraws the elongate bolt into the latch housing. Independently, when the cam is rotated by a separate handle on the other side the door, the cam plate likewise withdraws the elongate bolt into the latch housing.