Vehicle Seat Lifter Friction Control for Sliding Prevention
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Solution Overview
Problem
Existing lifter devices for vehicle seats face challenges in preventing sliding rotation during the pushed-down operation while maintaining the ability to lock the seat at the neutral position without increasing the operation load during the pulled-up operation.
Innovation Solution
A lifter device with an output shaft, support member, input member, feed portion, lock portion, and friction generating portion, where the friction generating portion includes an elastic body, rotating cam, and clutch portion that switches between friction-suppression and friction-on states based on the operation handle's position, applying friction only when lowering the seat to prevent sliding and rotating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a disc spring is configured to apply sliding frictional resistance force between the gear and support member at any time, then sliding rotation during pushed-down operation is prevented, but operation load increases during pulled-up operation
Solution Approach 1:
The friction generating portion dynamically changes its frictional resistance characteristics based on the operational phase. During pushed-down operation, the disc spring applies frictional resistance to prevent sliding rotation. During pulled-up operation, the frictional resistance is reduced or eliminated, allowing smooth operation without increased load. This dynamic adjustment resolves the contradiction between preventing sliding rotation and maintaining low operation load.
2Stability of the object's composition
If frictional resistance is applied to prevent sliding rotation during lowered position, then seat stability is improved, but operation smoothness deteriorates during raising
Solution Approach 1:
The friction generating portion transitions from a static friction application to a dynamic system that adjusts frictional resistance based on operational direction. During seat lowering, friction is applied to ensure stability and prevent sliding. During seat raising, the friction is reduced or removed to enable smooth operation. This dynamic behavior resolves the contradiction between stability and ease of operation.
3Reliability
If a ratchet type meshing structure is used for lock pawls, then rotation locking is achieved, but device complexity increases
Solution Approach 1:
The patent extracts the friction generation function from the meshing structure itself and implements it through a separate friction generating portion consisting of a disc spring and clutch portion. This separation allows the meshing structure to focus on its primary locking function while the friction generating portion handles the sliding prevention, thereby reducing overall device complexity while maintaining reliable rotation locking.
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 prevents sliding and rotation due to self-weight during the lowered position while maintaining a smooth operation and reduced operation load during seat raising, ensuring the seat can be locked at the neutral position without increased frictional resistance.
Implementation Method 1
an elastic body provided between the output shaft and the support member
Implementation Method 2
a friction generating portion configured to apply a frictional force to the rotation of the output shaft
Data Source
AI summary
A lifter device includes: an output shaft; a support member supporting the output shaft; an input member coupled to an operation handle; a feed portion transmitting forward and reverse rotation of the input member to the output shaft; a lock portion locking the rotation of the output shaft; and a friction generating portion applying a frictional force to the rotation of the output shaft. A rotating cam of the friction generating portion is a switching structure of switching to: a friction-suppression state when the operation handle is in a neutral position and when the operation handle is turned from the neutral position in a direction of raising the seat; and a friction-on state when the operation handle is turned from the neutral position in a direction of lowering the seat.