Door Latch Open-Link Assembly With Inertial Lever Retention
Solution Overview
Problem
Existing door latch devices face challenges in reducing component size and complexity, particularly in assembling the open link components, which complicates manufacturing operations.
Innovation Solution
A door latch device with an open link that includes a lever body and an inertial lever portion, where a support shaft is externally fitted into an insertion hole, and an engagement mechanism allows or restricts the insertion/removal of the support shaft based on the inertial lever's position, eliminating the need for separate screws and simplifying assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a support shaft portion is inserted through a screw insertion hole and a retaining screw is threaded to assemble the lever body and inertial lever portion, then the components can be reliably connected, but the manufacturing operation becomes complicated
Solution Approach 1:
The patent combines the support shaft portion and inertial lever portion into a single integrated component. The inertial lever portion is formed with a through-hole that directly receives the support shaft, eliminating the need for separate screw fastening operations. This merging of components reduces assembly steps while maintaining connection reliability through the direct fit of the support shaft in the through-hole.
Solution Approach 2:
The patent removes the retaining screw and screw insertion hole from the assembly by redesigning the connection mechanism. Instead of using a separate fastening component (screw), the design extracts the fastening function and integrates it into the structural fit between the support shaft and the through-hole of the inertial lever portion, simplifying the manufacturing operation.
2Volume of moving object
If the number of components is reduced and component size is downsized to meet spatial constraints, then the door latch device fits better in the door, but assembling becomes more complicated
Solution Approach 1:
The patent merges the support shaft and inertial lever into one component, reducing the total number of parts while maintaining compact dimensions. This integration allows the door latch device to meet spatial constraints without increasing assembly complexity, as the merged component is assembled as a single unit through the through-hole connection.
3Reliability
If the inertial lever portion is arranged at the non-operating position to prevent unexpected door opening, then safety is improved, but the door handle cannot be opened when needed
Solution Approach 1:
The patent employs a dynamic positioning mechanism where the inertial lever portion can shift between non-operating and operating positions based on applied forces. During normal operation, the inertial lever remains at the non-operating position for security. When sufficient force is applied to the door handle, the inertial lever dynamically transitions to the operating position, enabling the ratchet lever to engage and the door to open.
Solution Approach 2:
The patent uses preliminary anti-action by positioning the inertial lever at the non-operating position to preemptively prevent unauthorized door opening. The inertial lever is预先 positioned to block the ratchet lever, creating a preliminary barrier against theft. Legitimate opening requires overcoming this preliminary barrier through proper operational force.
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
Facilitates manufacturing by reducing assembly complexity and cost, while ensuring reliable operation and preventing unexpected door opening due to impact forces.
Implementation Method 1
a bias member configured to bias the inertial lever portion relative to the lever body in a rotation direction such that the inertial lever portion is maintained at the operating position
Implementation Method 2
an inertial lever portion configured to rotate relative to the lever body about a predetermined axis to move to an operating position and a non-operating position
Data Source
AI summary
A door latch device includes: an open link; and a ratchet lever, the open link including: a lever body; an inertial lever portion; and a bias member configured to bias the inertial lever portion relative to the lever body, wherein a support shaft portion is provided at one of the lever body and the inertial lever portion and an insertion portion having an insertion hole is provided in the other, and wherein an engagement mechanism is provided between the support shaft portion and the insertion portion, the engagement mechanism being configured to permit insertion/removal of the support shaft portion to/from the insertion hole when the inertial lever portion is located at a predetermined attachment/detachment position relative to the lever body, and prevent the insertion/removal of the support shaft portion to/from the insertion hole when the inertial lever portion is arranged at an operating position and a non-operating position.