Eccentric Pawl Latch Assembly for Reduced Release Force
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Solution Overview
Problem
Existing latch assemblies for car doors require increased force to release due to enhanced weather seal loads for improved occupant comfort, leading to higher operational effort.
Innovation Solution
A compact latch arrangement featuring a rotating claw, compression pawl, eccentric crank shaft assembly, and release actuator, where the pawl is rotated by an electromagnet to reduce the force needed to open the latch, utilizing an eccentric arrangement and a moveable abutment to manage turning moments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If weather seal clamping force is increased to improve occupant comfort and reduce wind noise, then seal performance is improved, but the force required to release the latch increases
Solution Approach 1:
The patent employs a dynamic pawl mechanism that changes its engagement state based on operational needs. The pawl is held in an engaged position with the latch bolt during normal operation to maintain high seal clamping force, but can be rotated to a disengaged position during release to reduce the force required. This dynamic state change allows the system to optimize both seal performance and ease of operation at different times.
Solution Approach 2:
The invention changes the mechanical parameter of pawl engagement by rotating it between engaged and disengaged positions. When disengaged, the pawl no longer constrains the latch bolt, effectively changing the force transmission path and reducing the release force requirement while maintaining seal integrity through the engagement mechanism.
2Device complexity
If a compact latch arrangement is used to reduce device complexity, then space is saved, but the mechanism for managing turning moments becomes more challenging
Solution Approach 1:
The patent combines multiple functions into integrated components. The eccentric crank shaft assembly performs both the function of converting rotational motion and managing turning moments simultaneously. The moveable abutment is integrated with the chassis to provide turning moment management without requiring separate complex structures, achieving compactness while managing mechanical stresses.
Solution Approach 2:
The moveable abutment acts as an intermediary element between the eccentric crank shaft assembly and the chassis. It mediates the turning moments generated by the eccentric mechanism, distributing and managing these forces through its movement along the chassis, thereby simplifying the overall mechanism while maintaining structural integrity.
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 reduces the force required to release the latch, enhancing user convenience while maintaining the seal integrity for occupant comfort, by leveraging an electromagnetically assisted mechanism to efficiently manage seal forces.
Implementation Method 1
the pawl is rotated by an electromagnet to reduce the force needed to open the latch
Data Source
AI summary
A latch assembly includes a chassis, a latch bolt moveably mounted on the chassis and having a closed position for retaining a striker and an open position for releasing the striker, a pawl having an engaged position at which the pawl is engaged with the latch bolt to hold the latch bolt in the closed position and a disengaged position at which the pawl is disengaged from the latch bolt, thereby allowing the latch bolt to move to the open position, an eccentric arrangement defining an eccentric axis and a pawl axis remote from the eccentric axis. The eccentric arrangement is rotatable about the eccentric axis, and the pawl is rotatable about the pawl axis. When the pawl moves from the engaged position to the disengaged position, the eccentric arrangement rotates in one of a clockwise and a counter-clockwise direction about the eccentric axis. With the pawl in the engaged position, a force applied to the pawl by the latch bolt creates a turning moment on the eccentric arrangement in the one of the clockwise and counter-clockwise direction, and the eccentric arrangement is prevented from rotating in said one of the clockwise and counter-clockwise direction by a moveable abutment.