Vehicle Door Latch Inertia Lock-Out Mechanism
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Solution Overview
Problem
Vehicle door latch mechanisms fail to prevent unintended opening during impact events, as existing mechanisms do not effectively respond to rapid changes in inertia to maintain the door in a closed position.
Innovation Solution
An inertia-activated lock-out mechanism is integrated into the vehicle door latch mechanism, featuring a locking member, counterweight, and biasing spring, which pivots to prevent the release member from moving the latch from a latched to an unlatched position when inertial forces exceed a threshold, ensuring the door remains closed during impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inertia-activated lock-out mechanism is added to the door latch mechanism, then the door's ability to remain closed during impact events is improved, but the device complexity increases
Solution Approach 1:
The inertia-activated lock-out mechanism is nested within the existing door latch mechanism housing. The locking member, counterweight, and biasing spring are contained within the same housing as the latch assembly, with the locking member integrated into the movement path of the release member. This nesting approach adds the inertia activation functionality without requiring a separate external mechanism, thereby improving reliability during impact while minimizing the increase in overall device complexity.
Solution Approach 2:
The lock-out mechanism is designed to be self-activating through inertia forces during impact events. The counterweight and biasing spring automatically engage the locking member into the locked position when inertial forces exceed the spring's biasing force, without requiring external sensors, actuators, or control systems. This self-service approach enhances reliability during impact while avoiding the complexity of electronic control systems.
2Reliability
If the locking member is positioned to engage the release member, then the door is prevented from opening during impact, but the ease of operation during normal conditions may be affected
Solution Approach 1:
The locking member is designed to be dynamically positioned based on inertial conditions. During normal operation, the biasing spring maintains the locking member in a retracted position that does not interfere with the release member's movement, allowing easy door operation. During impact events, inertial forces cause the counterweight to shift, moving the locking member into engagement with the release member to prevent door opening. This dynamic positioning resolves the contradiction between reliability during impact and ease of operation during normal conditions.
Solution Approach 2:
The system changes the positional parameter of the locking member based on inertial force parameters. Under normal gravitational conditions, the locking member remains in a non-interfering position. When inertial forces during impact exceed the biasing spring force, the locking member's position changes to engage the release member. This parameter-based control ensures reliable door closure during impact while maintaining ease of operation during normal conditions without requiring complex sensing or control systems.
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 mechanism effectively prevents the vehicle door from opening during impact events by engaging the locking member to block the release mechanism, maintaining door closure until the impact subsides, thus enhancing safety by maintaining the door's closed state during sudden changes in inertia.
Implementation Method 1
The counterweight is operatively coupled to the locking member to move the locking member to the locking position in response to an inertial force exceeding a threshold level
Data Source
AI summary
A latch assembly includes a housing, a door latch member and a release member. The door latch member pivots about a first pivot axis. The release member pivots about a second pivot axis spaced apart from the first pivot axis located within the housing operatively coupled to the latch retaining member. An inertia activated lock-out mechanism is fixedly attached to the housing and includes a locking member within the housing that pivots about a third pivot axis spaced apart from the first and second pivot axes. The first, second and third pivot axes are all parallel to one another at fixed locations within the housing. The locking member pivots between a locking position preventing movement of the release member and a non-interfering position in which the locking member is spaced apart from the release member allowing the release member to be movable.