Powerfold Mirror Actuator Load Path to Reduce Friction and Jamming
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Solution Overview
Problem
Existing powerfold exterior rearview mirror assemblies experience issues with high friction and jamming due to spring loads acting through multiple components during pivoting, leading to reduced stability and increased wear.
Innovation Solution
A powerfold actuator system that directs spring loads through an output gear to a base portion, bypassing a housing and lifter element during pivoting, using a spring element between the output gear and pivot post to stabilize the mirror head in the drive position and limit rotational forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the spring load acts through the housing portion and lifter element during pivoting, then the mirror head is supported, but friction and wear increase at the cut line seal
Solution Approach 1:
The patent extracts the spring load path from the housing portion and lifter element during pivoting operations. The spring is configured to engage directly with the pivot post, bypassing the housing and lifter element, thereby removing the source of friction and wear at the cut line seal while maintaining support for the mirror head assembly.
Solution Approach 2:
The patent introduces a direct engagement mechanism between the spring and pivot post as an intermediary load path. This bypasses the traditional path through the housing and lifter element, reducing friction at the cut line seal while still providing necessary support during pivoting operations.
2Ease of operation
If the output gear rotates freely relative to the base portion during powered pivoting, then the actuator can pivot the mirror head, but the spring load path becomes unstable
Solution Approach 1:
The patent implements a dynamic engagement system where the output gear selectively engages with the base portion during powered pivoting operations. The gear teeth engage with corresponding teeth on the base portion only when motor torque is applied, providing stability during actuation while allowing free rotation during manual positioning or when the motor is not engaged.
Solution Approach 2:
The patent extracts the rotational constraint from the continuous connection between the output gear and base portion. Instead of a fixed connection, the gear engages with the base portion only when needed for powered pivoting, allowing the spring load path to remain stable during motor actuation while permitting movement during manual operations.
3Stability of the object's composition
If the lifter element continuously engages the output gear, then rotation is limited, but friction and wear increase during operation
Solution Approach 1:
The patent implements periodic engagement of the lifter element with the output gear rather than continuous engagement. The lifter element engages the gear only during specific phases of the pivoting cycle when rotational limitation is needed, and disengages during other phases, thereby reducing cumulative friction and wear while maintaining necessary rotational control.
Solution Approach 2:
The patent creates a dynamic engagement system where the lifter element selectively engages and disengages from the output gear based on operational conditions. This dynamic interaction provides rotational limitation only when necessary, reducing continuous friction and wear compared to a permanently engaged system.
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
Enhances stability and reduces friction, extending the lifespan of the mirror assembly by minimizing torsional forces and preventing jamming, while allowing smooth pivoting between positions.
Implementation Method 1
A spring element is disposed between an upper surface of the output gear and an upper end of the pivot post to urge the output gear downward along the pivot post toward the base portion
Implementation Method 2
The actuator includes a flexible or resilient element that protrudes radially outward from the output gear to engage a tab at the housing portion to limit rotation of the output gear relative to the housing portion in one direction
Implementation Method 3
there are reduced forces and reduced friction at the cut line seal that is disposed between the mirror head and the mounting arm
Data Source
AI summary
A vehicular exterior rearview mirror assembly includes a powerfold actuator and a mirror head. The powerfold actuator includes an electrically-operable motor that rotatably drives a gear that is engaged with an output gear to pivot the housing portion relative to the output gear and a pivot post. The powerfold actuator includes a base portion fixed relative to the pivot post and the mounting arm, a first gear, a housing portion, a lifter element non-rotatably disposed at the base portion, and a spring element that urges the first gear toward the base portion. With the mirror head at the drive position, the spring element acts on the base portion via the output gear and housing portion. During powered pivoting of the housing portion relative to the pivot post, the spring element acts on the base portion via the output gear and not via the housing portion or the lifter element.