Crowned Worm Gear Drive for Vehicle Seat Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional power seat length adjuster assemblies in vehicles generate significant noise and vibrations due to the use of worm-worm gear and worm-helical gear drives, which are unpleasant for occupants and can lead to component degradation over time.
Innovation Solution
A seat adjuster assembly featuring a longitudinally crowned worm with a helical thread and a single-enveloping worm gear manufactured using an oversized hob, providing theoretical point contact and reduced sensitivity to misalignment and manufacturing errors, thereby minimizing noise and vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If traditional worm-worm gear and worm-helical gear drives are used, then the gear drive can transmit torque effectively, but significant noise and vibrations are generated
Solution Approach 1:
The patent applies local quality by modifying the contact characteristics of the worm gear drive. Specifically, it transitions from traditional line contact or face contact to point contact through the use of a ball drive mechanism combined with a rack and pinion system. This localized point contact reduces the contact area and distributes forces differently, thereby minimizing noise and vibrations while maintaining effective torque transmission.
Solution Approach 2:
The patent substitutes the traditional worm-worm gear or worm-helical gear mechanical system with a hybrid mechanism comprising a ball drive, rack, and pinion. This replacement eliminates the problematic meshing contact of worm gears that generates noise and vibrations, while achieving the same torque transmission function through a different mechanical approach that operates more quietly and smoothly.
2Power
If high reduction gear ratio is achieved in limited space, then smaller and faster electric motors can be used, but the gear drive complexity increases
Solution Approach 1:
The patent segments the gear drive function into distinct components: a ball drive mechanism for torque multiplication, a rack for motion conversion, and a pinion for directional control. This segmentation allows each component to perform its specific function efficiently, achieving high reduction ratios in a compact space without requiring complex multi-stage gear trains, thereby reducing overall system complexity while enabling smaller, faster motors.
3Power
If worm-worm gear and worm-helical gear drives are used, then torque can be transmitted, but component loosening and degradation occur over time
Solution Approach 1:
The patent replaces the traditional worm gear system with a ball drive, rack, and pinion mechanism. This substitution eliminates the sliding friction and contact stress inherent in worm gear meshing that cause component loosening and degradation. The new system uses rolling contact in the ball drive and simpler tooth engagement in the rack and pinion, significantly improving component durability and reliability while maintaining torque transmission capability.
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 solution effectively reduces noise and vibrations during seat adjustment, enhancing the durability and comfort of the seat assembly by localizing contact points and improving the gear drive's efficiency and robustness.
Implementation Method 1
The worm gear is manufactured using an oversized hob, providing theoretical point contact
Data Source
AI summary
A seat adjuster assembly including a housing, a worm, a worm gear, and a spindle screw is provided. The worm is disposed within the housing for rotation about a first axis and includes a helical thread. The worm gear is disposed within the housing for rotation about a second axis and is meshingly-engaged with the worm. The spindle screw extends through the housing and the worm gear for rotation about the second axis. The spindle screw is meshingly-engaged with the worm gear. The helical thread of the worm may be longitudinally crowned or double-crowned.