Door Latch Inertial Lever Return Mechanism
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Solution Overview
Problem
Existing door latch devices require complex replacement procedures, including replacing the open link and housing, to return the inertial lever portion to its operating position, making it difficult to readily replace the device.
Innovation Solution
A door latch device design that includes a pawl lever with a protruding portion to abut and return the inertial lever portion to its operating position during a preset return stroke, eliminating the need for housing replacement and simplifying the replacement process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inertial lever portion is designed to return to the operating position using a return protruding portion in the housing, then the door can be emergently opened after impact, but the replacement of the housing becomes complex and time-consuming
Solution Approach 1:
The invention divides the housing into two separable components: the main housing body and the removable cover portion. The cover portion contains the return protruding portion and can be detached and replaced independently from the main housing body. This segmentation allows the return mechanism to be restored by simply replacing the cover portion rather than the entire housing, thereby reducing replacement complexity and time while maintaining the emergency door opening capability.
2Ease of operation
If the inertial lever portion is maintained at the operating position by biasing force, then normal opening operation works correctly, but the door becomes vulnerable to unexpected opening during impact
Solution Approach 1:
The invention employs a dynamic return mechanism where the return protruding portion on the cover can engage with or disengage from the inertial lever portion based on operational conditions. During normal operation, the biasing force maintains the inertial lever at the operating position for easy door opening. During impact, the cover can be removed or repositioned to allow the inertial lever to rotate to the non-operating position, preventing unexpected door opening. This dynamic adjustment resolves the contradiction between ease of operation and impact protection.
Solution Approach 2:
The return protruding portion on the cover acts as an intermediary element between the operator and the inertial lever portion. It provides controlled interaction: during normal operation, it allows the biasing force to position the inertial lever correctly; during emergency or impact situations, the cover with the return protruding portion can be manipulated to restore or adjust the inertial lever's position, mediating between the conflicting requirements of easy operation and impact resistance.
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 allows for easy replacement of the door latch device without the need for complex housing replacement, facilitating quicker and more straightforward maintenance and upgrades.
Implementation Method 1
a releasing bias member configured to bias the inertial lever portion so that the inertial lever portion is maintained at the operating position relative to the lever body
Implementation Method 2
the pawl lever is provided with a protruding portion configured to abut on the inertial lever portion to return the inertial lever portion to the operating position when opening operation of the door handle is performed with a preset return stroke
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An open link 20 includes a lever body 21 and an inertial lever portion 22, between the lever body 21 and the inertial lever portion 22, a torsion spring 23 that shifts the inertial lever portion 22 rotating to a first non-operating position to a second non-operating position and maintains the inertial lever portion 22 at an operating position relative to the lever body 21, and an abutment protrusion 21c and a projection 22d that prevent the inertial lever portion 22 arranged at the second non-operating position from moving to the operating position are provided, and a pawl lever 14a releasing an engagement state of a pawl 14 with a latch 12 includes a protruding portion 14b that abuts on and returns the inertial lever portion 22 arranged at the second non-operating position to the operating position when opening operation of a door handle is performed with a return stroke.