Self-Disengaging Latch Actuator Clutch for Stall Engagement
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Solution Overview
Problem
Speed-based clutch assemblies for vehicle closure panels face challenges in maintaining engagement below minimum speed, leading to unreliable and unpredictable actuation, and unwanted disengagement during stall conditions.
Innovation Solution
A power actuator system with an electric motor, lead screw, nut, clutch plate, and biasing member that maintains engagement across all torque conditions, including stall, using electrical energy to inhibit backdriving and ensure reliable cinching of vehicle closure panels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If speed-based clutch assemblies are used to transfer torque between motor and gear assembly, then the clutch can be selectively engaged and disengaged based on motor speed, but the clutch cannot remain engaged when motor speed falls below the minimum required speed, leading to unreliable actuation
Solution Approach 1:
The patent replaces the speed-based mechanical clutch system with an electrically-controlled clutch mechanism. The electric motor's rotational force directly engages the clutch plate through electromagnetic control, eliminating the need for minimum speed thresholds. This substitution of mechanical speed-dependent engagement with electrical control ensures reliable clutch engagement across all motor speed conditions, including stall conditions where speed is zero.
Solution Approach 2:
The invention changes the control parameter for clutch engagement from motor speed to electrical signal presence. By using the presence or absence of electrical energy to the motor as the engagement/disengagement trigger rather than motor speed, the system achieves predictable and reliable clutch state control independent of speed variations.
2Reliability
If speed-based clutch assemblies are used, then torque transfer can be controlled, but the clutch assembly may disengage during stall conditions even when power is present, causing unwanted disengagement
Solution Approach 1:
The patent replaces the speed-based mechanical clutch system with an electrically-controlled clutch mechanism. The electric motor's rotational force directly engages the clutch plate through electromagnetic control, eliminating the need for minimum speed thresholds. This substitution of mechanical speed-dependent engagement with electrical control ensures reliable clutch engagement across all motor speed conditions, including stall conditions where speed is zero.
Solution Approach 2:
The electric motor itself serves the dual function of providing both the control signal and the driving force for clutch engagement. When electrical energy is present, it automatically maintains clutch engagement without requiring separate control mechanisms, ensuring the clutch remains engaged during stall conditions when power is supplied.
3Ease of operation
If clutch engagement is caused by speed conditions, then torque transfer can be controlled, but inherent variances within the clutch assembly cause engagement and disengagement over a range of speed rather than at a precise speed
Solution Approach 1:
The invention changes the control parameter for clutch engagement from motor speed to electrical signal presence. By using the presence or absence of electrical energy to the motor as the engagement/disengagement trigger rather than motor speed, the system achieves predictable and reliable clutch state control independent of speed variations.
Solution Approach 2:
The patent replaces the speed-based mechanical clutch system with an electrically-controlled clutch mechanism. The electric motor's rotational force directly engages the clutch plate through electromagnetic control, eliminating the need for minimum speed thresholds. This substitution of mechanical speed-dependent engagement with electrical control ensures reliable clutch engagement across all motor speed conditions, including stall conditions where speed is zero.
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 system ensures reliable and predictable engagement of vehicle closure panels across all torque conditions, preventing unwanted disengagement and maintaining the cinched state even during stall conditions, through the use of electrical energy to maintain the end face and clutch face in driving engagement.
Implementation Method 1
a biasing member configured to store energy and impart a bias between the end face and the clutch face
Implementation Method 2
a lead screw fixed to the drive shaft for rotation about the axis in a first direction in response to energization of the electric motor; a nut disposed about the lead screw, the nut having an end face and being configured for selective translation along the lead screw
Data Source
AI summary
A power actuator for a latch of a motor vehicle closure panel has an electric motor to rotate a lead screw about an axis. A nut is disposed about the lead screw for selective translation along the lead screw. A clutch plate is configured for selective rotation about the axis when engaged with the nut, with a biasing member biasing the nut out of engagement with the clutch plate when the electric motor is de-energized. A carrier member is coupled with the nut to cause the nut to translate into engagement with the clutch plate during rotation of the lead screw, whereupon the nut and carrier member co-rotate with the clutch plate and leadscrew. A driven member is operably coupled with the clutch plate and with the latch via a cable/rod, such that the driven member maintains the latch in a cinched state when the electric motor is energized.