Motorcar Mirror Gear Rod Preloading for Slackness Elimination
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Solution Overview
Problem
Existing mirror adjustment devices for motorcars face issues with slackness and judder due to manufacturing tolerances in polymer components, leading to delayed response characteristics and increased abrasion, and require large installation space with existing designs.
Innovation Solution
The device employs circular arc gear rods and springy pressing mechanisms to eliminate relative movement between gear rods and gears, combined with safety clutch means that allow gears to slip in overload conditions, reducing abrasion and noise, and minimizing installation space requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If polymer components are used to reduce cost and weight, then manufacturing cost and weight are reduced, but manufacturing precision deteriorates resulting in slackness and judder
Solution Approach 1:
The patent introduces a preloaded spring mechanism that changes the operational parameters of the gear rod connection. The spring applies a constant force to eliminate backlash and ensure continuous contact between the gear rod and gear, compensating for the inherent precision limitations of polymer components while maintaining the cost and weight benefits of using plastics.
2Stability of the object's composition
If friction damping is applied to counteract judder, then judder is reduced, but abrasion increases resulting in degeneration over time
Solution Approach 1:
The patent replaces the traditional friction-based damping mechanism with a spring-based preloading system. Instead of relying on friction between contacting surfaces to damp vibrations, the spring mechanism maintains continuous positive contact pressure between the gear rod and gear, providing stability through elastic deformation rather than frictional resistance, thereby eliminating abrasion and extending service life.
3Reliability
If worm drives are used to prevent back driving, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent extracts the back-driving prevention function from the worm drive gear train and implements it through a simpler spring-loaded detent mechanism. The spring maintains continuous contact between the gear rod and gear, creating a one-way locking effect that prevents back driving without requiring complex worm gear geometry, thereby reducing device complexity while maintaining reliability.
4Ease of operation
If gear rods are made commutable to allow manual adjustment, then ease of operation is improved, but slackness increases resulting in delayed response
Solution Approach 1:
The patent implements a dynamic preloading system where the spring force automatically adjusts during operation. During manual adjustment, the spring allows the gear rod to commute freely for ease of operation. During automated operation, the spring's continuous contact pressure eliminates backlash, ensuring immediate response without delayed movement, thus resolving the contradiction between ease of operation and response time.
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
This solution improves response characteristics by damping the gears and gear rods without causing abrasion, reduces noise and wear in overload conditions, and allows for a more compact design that fits in smaller spaces while maintaining low cost and lightweight construction.
Implementation Method 1
the safety clutch means comprise a disc spring having a friction face forced against a corresponding friction face on another gear train member
Implementation Method 2
the safety clutch means comprise a disc spring having a friction face forced against a corresponding friction face on another gear train member
Data Source
AI summary
A device to adjust the orientation of a mirror of a motorcar includes a body to accommodate a first and a second electric motor and a first and a second gear driven by first and second motor respectively. Gear rods are formed as circular arc sections and the body accommodates means to resiliently press the first and second gear rod against the first and second gears, respectively, eliminating relative movement between the gearing of the gear rods and the gears in operation conditions. Each of the gears include a safety clutch, allowing the gears to slip in overload conditions.