Power Door Latch Release Mechanism With Lever Noise Reduction
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Solution Overview
Problem
Existing power-operated vehicle door latches generate noise due to sudden disengagement of components caused by high friction, requiring motors with excessive output force to overcome friction, leading to increased cost, size, and weight.
Innovation Solution
A power latch assembly with a spring-biased noise reduction mechanism, utilizing a power actuator to drive a worm gear that pivots a first lever relative to a power release gear, engaging a second lever to move a pawl between ratchet holding and releasing positions, minimizing contact and noise generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a motor with sufficient output force is provided to overcome friction between pawl and ratchet, then the door can be opened under high seal load and ice conditions, but the motor size, weight, and cost increase
Solution Approach 1:
A spring-loaded cam mechanism is introduced as an intermediary between the motor and the pawl-ratchet system. The cam converts rotational motor motion into linear displacement that pushes the pawl off the ratchet tooth, mediating the force transmission and reducing the motor's direct burden.
Solution Approach 2:
The system transitions from a static friction-overcoming approach to a dynamic cam-based release mechanism. The cam's profile is designed to provide the necessary force at specific points in the rotation cycle, allowing the motor to operate with lower continuous torque while still achieving reliable door release.
2Ease of operation
If high output force motor is used to overcome friction, then pawl can be moved from ratchet holding to releasing position, but noise is generated due to sudden disengagement
Solution Approach 1:
The spring-loaded cam acts as a mediator that controls the pawl's disengagement from the ratchet. The spring provides a cushioning effect during the transition, while the cam's profile ensures smooth, controlled movement rather than sudden impact, reducing noise generation.
3Reliability
If motor output force is increased well in excess of normal needs, then door can be opened in increased seal load conditions, but cost and device complexity increase
Solution Approach 1:
The cam mechanism introduces dynamic force multiplication. During normal operation, the motor operates at low torque. When door release is needed, the cam's geometric profile converts the motor's rotational motion into amplified linear force that reliably moves the pawl, even under high seal load conditions.
Solution Approach 2:
The system changes the force application parameters through the cam profile design. Instead of requiring high continuous motor torque, the cam provides high instantaneous force during the critical disengagement phase, while the spring maintains appropriate force levels during other phases of operation.
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 noise during operation by minimizing contact between levers, allowing for efficient door opening without the need for high-output motors, thus optimizing size, weight, and cost.
Implementation Method 1
a spring coupled to the power release gear for conjoint movement with the power release gear, and a first lever coupled to the power release gear for pivotal movement relative to the power release gear, and a second lever. The spring biases the first lever to a rest position in spaced relation from the rib
Implementation Method 2
a power actuator configured to drive a worm gear, with a power release gear configured to be driven about a power release gear axis in response to the worm gear being driven
Implementation Method 3
a power door latch assembly equipped with a power release motor configured to drive a gear reduction
Data Source
AI summary
A power latch assembly has a ratchet moveable between a striker capture position and a striker release position and a pawl moveable between a ratchet holding position to maintain ratchet in the striker capture position, and a ratchet releasing position to release ratchet to the striker release position. A power actuator drives a power release gear having a rib. A spring is coupled to power release gear, a first lever is coupled to power release gear, and a second lever is coupled to pawl. Spring biases first lever to a rest position spaced from rib. Power actuator drives power release gear from a home position to a deployed position, whereupon first lever engages second lever and deflects against the spring bias from the rest position to engage rib, whereupon rib drives first lever, which drives second lever to move pawl from the ratchet holding position to the ratchet releasing position.