Vehicle Seat Gear Assembly With Conical Teeth for Low Backlash
Solution Overview
Problem
Existing gear reduction mechanisms in automotive seat adjusters face challenges in achieving high gear ratios, compact size, reduced noise, competitive pricing, and anti-back drive capability, while maintaining mechanical efficiency and minimizing backlash, which are essential for precise seat adjustments.
Innovation Solution
The implementation of conical involute gears with tapered tooth thickness, root, and diameter, combined with a two-stage gear reduction mechanism, including a worm-helical and planetary-type transmission, eliminates backlash and provides anti-back drive capability, enhancing mechanical efficiency and reducing friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high reduction gear ratio is achieved using conventional worm and worm-wheel gear drives, then anti-back drive capability is provided, but mechanical efficiency decreases to 50% or lower
Solution Approach 1:
The gear drive is divided into two independent stages: a first-stage worm-helical gear reduction mechanism providing anti-back drive capability, and a second-stage planetary-type reduction mechanism providing high reduction ratio with improved efficiency. This segmentation allows each stage to specialize in one function, resolving the contradiction between anti-back drive capability and mechanical efficiency.
Solution Approach 2:
The patent introduces an intermediary coupling mechanism between the worm-helical gear stage and planetary gear stage that allows torque transmission while maintaining the anti-back drive capability of the worm gear and the efficiency of the planetary gear. The intermediary coupling enables the two different gear types to work together without compromising either function.
2Productivity
If a two-stage gear transmission solution is used to achieve high gear ratio and compact size, then mechanical efficiency improves, but device complexity increases
Solution Approach 1:
The patent merges the anti-back drive function and high reduction ratio function into a single integrated two-stage transmission unit. The worm-helical gear stage and planetary gear stage are combined in a compact arrangement where the output of the first stage directly drives the second stage, achieving both high efficiency and high reduction ratio without excessive complexity.
Solution Approach 2:
The two-stage gear transmission mechanism serves multiple functions simultaneously: it provides anti-back drive capability, achieves high reduction ratio (300:1-700:1), maintains compact size, and improves mechanical efficiency. This multi-functionality reduces the need for separate mechanisms, thereby managing complexity while achieving multiple goals.
3Device complexity
If conventional single-stage reduction mechanisms are used, then device complexity is reduced, but the ability to achieve high gear ratio with compact size and reduced noise is compromised
Solution Approach 1:
The planetary gear stage is nested within the overall transmission assembly, with the planetary gears positioned inside the annular space created by the worm-helical gear stage. This nesting arrangement allows the high reduction ratio planetary mechanism to be housed within a compact footprint, achieving high gear ratio density without proportionally increasing external dimensions or complexity.
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 achieves a high gear ratio with improved mechanical efficiency, reduced backlash, and effective anti-back drive capability, protecting the electric motor and maintaining seat position stability under external loads, with estimated efficiency ranging from 30-35%.
Implementation Method 1
conical involute gears with tapered tooth thickness, root, and diameter
Implementation Method 2
worm-helical and planetary-type transmission
Implementation Method 3
planetary-type transmission
Implementation Method 4
reduced friction
Data Source
AI summary
A vehicle seat adjustment mechanism includes a first component and a second component that is movable relative to the first component. A drive mechanism is drivingly connected to the second component for moving the second component relative to the first component. The drive mechanism includes a drive motor drivingly connected to a first gear member having conical involute teeth. A second gear member includes conical involute teeth in meshing engagement with the conical involute teeth of the first gear member. The conical involute teeth have a tapered tooth thickness, a tapered root and a tapered outside diameter.