Seat Reclining Adjuster With Movable Bearing for Backlash Control
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Solution Overview
Problem
Existing reclining adjusters for vehicle seats suffer from backlash and rattling issues due to manufacturing errors and friction variations, leading to discomfort and abnormal sounds when locking the seat back, and conventional solutions either fail to adequately address clearance variations or hinder smooth rotation.
Innovation Solution
A reclining adjuster with a worm supported by both fixed and movable bearings, where the movable bearing is pressed to incline the worm's axial center, reducing backlash and clearance through frictional force, and an engaging member locks the worm after speed reduction, preventing sudden engagement and ensuring smooth operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the worm is pressed against the worm wheel to stop rotation through friction, then the locking reliability is improved, but the backlash clearance increases causing rattling and abnormal sound
Solution Approach 1:
The bearing supporting the worm is divided into two separate bearings: a fixed bearing that maintains the worm's rotational position and a movable bearing that can move in the axial direction to adjust backlash. This segmentation allows independent optimization of locking reliability and backlash control without compromising either function.
Solution Approach 2:
The movable bearing is designed to dynamically adjust its position in the axial direction based on operational conditions. During rotation, it maintains appropriate backlash for smooth operation; during locking, it moves to reduce clearance and eliminate rattling. This dynamic adaptation resolves the contradiction between maintaining smooth rotation and preventing abnormal sounds.
2Manufacturing precision
If a compression spring continuously presses the worm toward the gear side, then the backlash is reduced, but the smooth rotation during operation is hindered
Solution Approach 1:
The movable bearing provides dynamic backlash adjustment without continuous spring pressure on the worm. The bearing can move to reduce backlash when needed while maintaining smooth rotation during operation, eliminating the contradiction between precision control and operational smoothness.
Solution Approach 2:
The movable bearing acts as an intermediary between the compression spring and the worm. Instead of the spring directly pressing the worm (which hinders rotation), it presses the movable bearing, which then adjusts the worm's position indirectly. This mediation allows backlash control while preserving smooth rotational operation.
3Object-generated harmful factors
If the worm position is adjusted to eliminate clearance in the thrust direction, then the rattling is suppressed, but the smooth rotation during reclining is interrupted
Solution Approach 1:
The movable bearing enables dynamic adjustment of the worm's axial position based on operational phase. During reclining, it maintains clearance for smooth rotation; during locking, it eliminates clearance to suppress rattling. This temporal separation of functions resolves the contradiction between rattling suppression and smooth rotation.
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 backlash and clearance, suppressing rattling and abnormal sounds, while maintaining smooth rotation and reducing discomfort during locking, by using a combination of cams and a latch member to control the worm's rotation and engagement.
Implementation Method 1
pressing the movable bearing to move the worm and the movable bearing toward the worm wheel by frictional force
Implementation Method 2
a ball supported in a recess formed in the movable bearing moves slightly along an inner surface of the recess
Data Source
AI summary
Reduces backlash and clearance in a thrust direction of a worm when engaging a seat back to more securely prevent the generation of abnormal noise that before. A movable bearing 12 is pressed by cams 21, 22 that are pressing members, when the seat back is stopped at a predetermined angle, to approach a worm wheel 5. A ball 14 disposed in a recess 12a of the movable bearing 12 moves slightly along an inner surface of the recess 12a so a worm 4 is pressed to the worm wheel 5 side and pressed to the fixed bearing 11 side, and a latch member 23 that is a engaging member engages the worm 4 to inhibit rotation of the worm wheel 5 thereby securely holding that state. Since the movable bearing 12 moves to the worm wheel 5 side, the substantial movement range of the ball is wider compared to a structure that supports a ball only at a fixed bearing, and the range of displacement of the worm 4 by being pressed by the ball is substantially larger.