Bi-directional Power Release Mechanism for Vehicle Door Latch
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Solution Overview
Problem
Existing power door latch assemblies require motors with excessive output force to overcome friction and high seal loads, leading to increased size, weight, and cost.
Innovation Solution
A power latch assembly with a bi-directional power release mechanism that applies a first torque in one direction and a second, greater torque in the opposite direction, optimizing motor size and output force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a motor with excessive output force is used to overcome friction and high seal loads, then the pawl can be moved from the ratchet holding position to the releasing position under high seal loads, but the motor size, weight, and cost increase
Solution Approach 1:
The system dynamically switches between two torque modes based on operating conditions. The bi-directional power release mechanism provides a first torque for normal operation and a second, greater torque for high seal load conditions. This dynamic adaptation allows the motor to be sized for normal conditions while still handling extreme cases, resolving the contradiction between reliability under high load and motor weight.
Solution Approach 2:
The invention changes the torque parameter delivered by the motor through the bi-directional power release mechanism. By providing different torque levels (first torque for normal operation, second greater torque for high seal load) based on directional movement, the system optimizes motor sizing while maintaining the ability to overcome high seal loads when necessary.
2Reliability
If a motor with excessive output force is used to overcome friction and high seal loads, then the pawl can be moved from the ratchet holding position to the releasing position under high seal loads, but the device complexity increases
Solution Approach 1:
The bi-directional power release mechanism serves multiple functions: it acts as a normal drive mechanism during regular operation and as a torque amplification mechanism during high seal load conditions. This multi-functionality eliminates the need for separate systems for normal and emergency operation, reducing overall device complexity while maintaining reliability under all conditions.
3Reliability
If a motor with excessive output force is used to overcome friction and high seal loads, then the pawl can be moved from the ratchet holding position to the releasing position under high seal loads, but the cost increases
Solution Approach 1:
The dynamic torque switching capability allows the system to use a smaller, less expensive motor designed for normal operating conditions while still providing the necessary force for high seal load situations through the bi-directional power release mechanism. This resolves the contradiction between reliability under extreme conditions and manufacturing cost.
Data Source
AI summary
A power latch assembly for a vehicle door of a motor vehicle includes a ratchet configured for movement between striker capture and striker release positions, wherein the ratchet is biased toward the striker release position, and a pawl configured for movement between a ratchet holding position, whereat the pawl maintains the ratchet in the striker capture position, and a ratchet releasing position, whereat the pawl releases the ratchet to the striker release position. A powered actuator is energizable to move in a first direction to move the pawl under a first release torque from the ratchet holding position to the ratchet releasing position and the powered actuator is energizable to move in a second direction to move the pawl under a second release torque from the ratchet holding position to the ratchet releasing position, wherein the second release torque is greater than the first release torque.