Vehicle Seat Reclining Device Backlash Prevention
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Solution Overview
Problem
Existing reclining devices for vehicle seats are too large and heavy, leading to reduced engagement strength and increased backlash, which can cause the seatback to rock or recline unexpectedly, compromising passenger safety.
Innovation Solution
A compact reclining device design featuring a socket block, bearing, and power transmission unit that minimizes gear press angle and backlash by using a ring-shaped center protrusion and operating protrusion to ensure precise engagement between external and internal gears, allowing for efficient power transmission with a small-output motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of the reclining device is decreased, then the disposing space and weight are reduced, but the engagement strength between geared parts decreases and backlash is caused
Solution Approach 1:
The invention changes the geometric parameters of the gear system by minimizing the gear press angle to 5-10 degrees, which fundamentally alters the engagement characteristics between the external and internal gears. This parameter change allows for compact dimensions while maintaining sufficient engagement strength through optimized force distribution.
Solution Approach 2:
The invention introduces a dynamic adjustment mechanism through the wedge-shaped blocks and springs that automatically adjust the engagement force between gears during operation. This dynamic system compensates for the reduced size by actively maintaining optimal engagement conditions, preventing backlash while keeping the overall device compact.
2Power
If the gear press angle is minimized, then the operational efficiency is increased and sufficient power is obtained from small-output motor, but the design complexity increases
Solution Approach 1:
The invention merges multiple functions into the power transmission unit: the external gear, internal gear, wedge-shaped blocks, and springs work together as an integrated system. This combination achieves both the minimized gear press angle for high efficiency and the necessary structural complexity in a unified design, rather than separate components.
Solution Approach 2:
The power transmission unit serves multiple functions simultaneously: it transmits power from the motor, maintains minimal gear press angle for efficiency, provides self-adjusting engagement through springs, and prevents backlash. This multi-functionality achieves high operational efficiency while consolidating what could be separate complex systems into one unit.
3Ease of manufacture
If the shape of wedge blocks and cams is simplified, then the manufacturing cost is reduced and productivity is improved, but the engagement precision and backlash prevention capability are compromised
Solution Approach 1:
The invention simplifies the overall shape of wedge blocks and cams while maintaining critical engagement parameters through precise dimensional control. The wedge blocks have a basic simple geometry that is easy to manufacture, but include specific angled surfaces and dimensions that ensure precise gear engagement and backlash prevention.
Solution Approach 2:
The power transmission unit is segmented into distinct functional elements: the simplified wedge blocks for force application, the springs for adjustment, and the gear interfaces for power transmission. This segmentation allows each component to be manufactured separately with simpler geometries while maintaining overall engagement precision through their coordinated design.
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 prevents backlash and vibration noise, reduces weight and manufacturing costs, and allows for a compact design that can be freely adapted to various spaces while maintaining sufficient engagement strength and operational efficiency.
Implementation Method 1
a bearing that is inserted in the center hole of the external gear bracket
Implementation Method 2
a power transmission unit that is in close contact to the bearing while covering the other portion of the ring-shaped center protrusion, which is not covered by the operating protrusion, and rotates along the ring-shaped center protrusion by contact with the operating protrusion when the shaft rotates
Data Source
AI summary
The present invention relates to a reclining device of a seat for a vehicle, which makes it possible to prevent backlash between an external gear 12 and an internal gear 22 in stop, resulting in preventing a vibration noise due to movement of the seatback. Further, it is possible to obtain sufficient power from even a small-output motor in operation, by minimizing the gear press angle to increase the operational efficiency. In addition, it is possible to design a compact reclining device by simplifying the shape and reduce the size of assemblies of wedge blocks 70, 120 and cams 80, 110, resulting in reducing the weight and the manufacturing cost and making it possible to freely designing the reclining device, depending on a disposing space.