Seat Back Worm Gear Locking Mechanism for Backlash-Free Rotation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing seat back rotation movement control mechanisms suffer from backlash and clearance issues during locking, leading to looseness and abnormal sounds, and are prone to whirling vibrations and incomplete rotation stoppage due to incorrect worm positioning, which affects smooth rotation and reliability of the locking mechanism.
Innovation Solution
A rotation movement control mechanism featuring two worm wheels arranged across the worm, with a driving worm wheel and a driven worm wheel that engage to reduce backlash and allow stepless locking, utilizing rotating and locking fulcrums with elastic support and an eccentric shaft to maintain stable rotation and enhanced locking reliability, even under external loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the worm is pushed against the worm wheel to eliminate backlash, then locking force is improved, but whirling vibration and abnormal sounds occur due to incorrect worm positioning
Solution Approach 1:
A positioning member is introduced as an intermediary element between the worm and the worm wheel. This positioning member accurately positions the worm in the thrust direction, enabling the worm to engage properly with the worm wheel teeth without generating whirling vibration or abnormal sounds during locking
Solution Approach 2:
The positioning member pre-positions the worm at the correct location before the locking action occurs. By establishing accurate worm positioning in advance, the system prevents whirling vibration and ensures smooth engagement when the worm is pushed against the worm wheel for locking
2Reliability
If the worm is pushed against the worm wheel to eliminate clearance in thrust direction, then locking reliability is improved, but the worm cannot be stopped at stepless positions due to engagement groove intervals
Solution Approach 1:
The positioning member acts as a mediator that enables continuous positioning of the worm along the thrust direction. It allows the worm to be stopped at any position rather than being constrained to discrete intervals defined by engagement grooves,从而实现 stepless positioning while maintaining locking reliability
Solution Approach 2:
The system transitions from a static engagement groove structure with fixed intervals to a dynamic positioning mechanism. The positioning member allows the worm to be positioned continuously along the thrust direction, enabling smooth, stepless adjustment and stopping at any desired position
3Device complexity
If a single worm wheel is used, then device complexity is reduced, but backlash and clearance cause looseness and abnormal sounds
Solution Approach 1:
The positioning function and the worm wheel's rotation function are merged into a coordinated system. The positioning member works together with the worm wheel to simultaneously eliminate backlash and prevent abnormal sounds, achieving the effect of multiple components without proportionally increasing complexity
Solution Approach 2:
The positioning member serves as an intermediary that coordinates the interaction between the worm and worm wheel. It eliminates clearance and backlash while maintaining a relatively simple overall structure by adding only one essential component
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 mechanism ensures smooth rotation and improved locking reliability by minimizing backlash and whirling vibrations, maintaining engagement under large loads, and preventing seat back inclination, thus enhancing occupant safety and escapability.
Implementation Method 1
the one bearing part arranged in the one end portion side in the axial direction of the worm has an elastic part that elastically supports the rotating fulcrums, the elastic part is flexed in the axial direction by the worm being displaced in the axial direction at the time of locking, and thereby, the supporting position of the one bearing part in the one end portion in the axial direction of the worm is changed from the rotating fulcrums to the locking fulcrum
Data Source
AI summary
A structure in which two worm wheels are disposed across a worm provides an increase in locking reliability while maintaining stable operation during rotation. At the time of rotation, respective rotating fulcrums set at both end portions in an axial direction of a worm are supported by bearing parts. At the time of locking, a locking fulcrum set at an eccentric position on one end portion in the axial direction of the worm is supported by one bearing part, while on the other end portion in the axial direction, the rotating fulcrum is supported by the other bearing part as is. As a result, the angle of lead of the worm supported by the pair of bearing parts is changed between the time of rotation and the time of locking and becomes smaller at the time of locking than at the time of rotation, whereby an increase in locking reliability can be achieved.