Vehicle Door Latch Speed-Based Locking Mechanism
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Solution Overview
Problem
Vehicle door latches often unlatch during side impacts due to the inertia-driven movement of door handles, which existing counterweights and designs fail to adequately prevent.
Innovation Solution
A speed-based locking device is integrated into the vehicle door system, using a housing with guide channels and a lock member to prevent excessive lengthwise movement of the elongated flexible member or cable, thereby preventing unlatching by engaging a stop surface if the movement exceeds a predefined speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If counterweights are added to door handles to prevent movement during side impact, then door latch reliability improves, but device complexity increases
Solution Approach 1:
The patent extracts the speed-sensing function from the door handle assembly and places it in the latch mechanism itself. The speed-based locking device is integrated into the latch mechanism, separating the sensing function from the handle and eliminating the need for counterweights in the handle assembly.
Solution Approach 2:
The patent introduces a speed-based locking device as an intermediary component between the cable and the latch mechanism. This locking device acts as a mediator that selectively prevents cable movement based on speed detection, providing a more elegant solution than adding mass to the handle.
2Reliability
If the door handle is made more massive to resist inertia-driven movement, then latch reliability improves, but weight of moving object increases
Solution Approach 1:
The patent removes the need for additional mass in the door handle by extracting the protection function and relocating it to the latch mechanism. The speed-based locking device provides the necessary protection without adding weight to the moving handle assembly.
Solution Approach 2:
The patent changes the approach from modifying the mass parameter of the door handle to modifying the speed parameter detection and response in the latch mechanism. By detecting cable movement speed and responding accordingly, the system protects the latch without increasing handle weight.
3Reliability
If the latch mechanism is made more complex to prevent unintended unlatching, then reliability improves, but ease of operation deteriorates
Solution Approach 1:
The patent applies dynamics by making the locking state of the locking device change based on the speed of cable movement. During normal operation at low speeds, the locking device allows free movement. During high-speed events like side impacts, the locking device engages to prevent unlatching, providing adaptive protection without affecting normal ease of operation.
Solution Approach 2:
The patent uses parameter changes by detecting the speed parameter of cable movement and changing the locking state accordingly. The speed-based locking device transitions between locked and unlocked states based on whether the cable movement exceeds a predetermined speed threshold, maintaining ease of operation under normal conditions while providing protection during impacts.
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
Effectively prevents unlatching of the door latch during high-speed events like side impacts, ensuring the door remains closed by limiting cable movement to safe speeds, thus enhancing safety and reliability.
Implementation Method 1
A resilient member rotationally biases the lock member whereby the lock member tends to rotate in a first direction about the cable relative to the base
Implementation Method 2
the follower engages the stop surface rather than the ramp surface if the cable and lock member are moved relative to the base at a speed exceeding an allowable value whereby rotational inertia of the lock member causes the follower to disengage from the ramp surface
Data Source
AI summary
A vehicle door includes a door structure and a movable door handle that is connected to a latch mechanism by a cable. A rotatably biased stop member is connected to the cable. The vehicle door further includes a housing having a channel that receives portion of the stop member. The channel includes first and second linear portions and a transverse stop portion that is engaged by the follower to prevent further lengthwise movement of the lock member and cable if a speed of the cable exceeds an allowable value.