Exterior Mirror Actuator Detent Design for Low-Friction Powerfolding

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Solution Overview

Problem

Existing powerfold exterior rearview mirror assemblies face challenges in efficiently pivoting the mirror head between drive and folded positions due to high forces and friction at the cut line seal, which increases the power required from the motor and can lead to premature wear.

Innovation Solution

A powerfold actuator system with a primary detent assembly for retaining the mirror head at either the folded or drive position and a secondary detent assembly that engages when the primary detent disengages, allowing the mirror head to lift relative to the mounting base without compressing the spring, thereby reducing friction and power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the mirror head is pivoted between drive and folded positions using a conventional powerfold actuator, then the mirror head can be retained at either position, but high forces and friction occur at the cut line seal which increases power consumption and causes premature wear

Engineering Contradiction:

Improvemirror assembly lifespanVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The detent mechanism is divided into two separate assemblies: a primary detent assembly that engages with the output gear to provide primary retention, and a secondary detent assembly that engages with the input shaft to provide secondary retention. This segmentation allows the mirror head to be supported by both detents simultaneously, reducing the load and friction at the cut line seal, thereby reducing power consumption and extending assembly lifespan.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The secondary detent assembly acts as an intermediary mechanism that engages with the input shaft to provide additional support and retention. By introducing this intermediate retention point, the system reduces the direct friction and force requirements at the cut line seal, leading to lower power consumption and reduced wear on critical components.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If a single detent assembly is used to retain the mirror head, then the structure is simpler, but the forces and friction at the cut line seal increase leading to higher power requirements

Engineering Contradiction:

Improveactuator structureVSAvoidforce at cut line seal

Core Design Contradiction:

Device complexityVSForce

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

3Force

If the spring is compressed to raise the mirror head during pivoting, then the mirror head can be lifted relative to the mounting base, but the power required from the motor increases

Engineering Contradiction:

Improvemirror head lifting forceVSAvoidmotor power

Core Design Contradiction:

ForceVSUse of energy by moving object

Solution Approach 1:

The secondary detent assembly is pre-configured to engage with the input shaft at a specific position during the pivoting operation. This preliminary engagement provides mechanical support that assists in lifting the mirror head relative to the mounting base without requiring excessive compression of the spring, thereby reducing the power required from the motor.

Inventive Principle:

Principle #10Preliminary action

4Reliability

If the cut line seal experiences high friction during pivotal movement, then the seal may provide adequate retention, but the power consumption increases and wear accelerates

Engineering Contradiction:

Improveseal retentionVSAvoidoperational efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes the retention mechanism from relying solely on friction at the cut line seal to using positive engagement through two separate detent assemblies. This parameter change from friction-based retention to mechanical engagement reduces the friction and power consumption while maintaining reliable retention.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20240367585A1Vehicular exterior mirror with actuator

Publication Date: 2024.11.07 MAGNA MIRRORS OF AMERICA INC

AI summary

A vehicular exterior rearview mirror assembly includes a mirror head and a mounting base configured for mounting the mirror assembly at a side of a vehicle. An actuator is operable to move the mirror head relative to the mounting base between at least an extended position and a folded position. The actuator includes a first detent interface and a second detent interface. The first detent interface is engaged when the actuator moves the mirror head to the folded position or the extended position. The second detent interface is not engaged as the actuator moves the mirror head between the folded position and the extended position. The second detent interface is engaged when the mirror head is manually moved to the folded position or the extended position. The first detent interface is not engaged as the mirror head is manually moved between the folded position and the extended position.