Vehicle Armrest Wrap Spring Brake Axis Locking
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Solution Overview
Problem
Existing armrest devices in vehicles face challenges in achieving a simple, space-saving, and low-noise design for their locking mechanisms, which are often complex and inefficient.
Innovation Solution
The armrest device features a split swivel axis with a wrap spring brake that differentiates between frictional locking and release based on the direction of movement, utilizing a helical wrap spring with varying frictional engagement to allow smooth operation and easy manual actuation, ensuring reliable and quiet operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional locking device is used for the armrest, then the armrest can be secured in positions, but the device becomes complex and space-consuming
Solution Approach 1:
The locking function is merged with the swivel axis itself. The wrap spring brake is directly associated with the swivel axis, combining the rotation support and locking functions into a single integrated structure, eliminating the need for separate locking mechanisms
Solution Approach 2:
The wrap spring brake automatically locks and releases the armrest based on the direction of movement without requiring external control systems. The frictional locking engages passively when the armrest is swivelled towards the not-in-use position and releases when swivelled towards the armrest position
2Reliability
If a conventional locking device is used for the armrest, then the armrest can be secured in positions, but the device requires more installation space
Solution Approach 1:
The locking mechanism is merged with the swivel axis structure. The wrap spring brake interacts directly with the base axis section and armrest axis section, eliminating the need for additional space-consuming locking components
Solution Approach 2:
The wrap spring is nested around the swivel axis, with the helical wrap spring coaxially surrounding the armrest axis section and base axis section. This nested arrangement allows the locking mechanism to occupy minimal space within the existing structural envelope
3Reliability
If a locking device with high frictional locking is used, then the armrest is securely locked, but the armrest requires excessive force to actuate
Solution Approach 1:
The frictional locking characteristic is made dynamic rather than static. The wrap spring brake provides high frictional locking in one direction (when swivelled towards not-in-use position) and low frictional locking in the opposite direction (when swivelled towards armrest position), allowing easy manual actuation while maintaining secure locking
Solution Approach 2:
Different frictional locking characteristics are applied to different directions of movement. The wrap spring brake creates asymmetric friction: high friction when the armrest is swivelled towards the not-in-use position to ensure secure locking, and low friction when swivelled towards the armrest position to enable easy manual operation
4Reliability
If a conventional locking mechanism is used, then the armrest can be secured, but the movement between positions generates noise
Solution Approach 1:
The wrap spring brake automatically adjusts its frictional characteristics during movement. The stepless operation is achieved through the elastic deformation of the wrap spring windings, which gradually engage and disengage from the swivel axis surface, eliminating sudden impacts and noise
Solution Approach 2:
The friction coefficient between the wrap spring and swivel axis is dynamically changed during operation. The elastic deformation of the wrap spring windings creates a progressive engagement process that transforms the abrupt frictional contact into a smooth, stepless transition, reducing noise during movement
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
This design results in a simple, space-efficient, and functionally reliable locking mechanism that enables smooth, quiet movement of the armrest between positions, suitable for various vehicle types, and allows easy manual operation without excessive force.
Implementation Method 1
The wrap spring brake operates on the basis of increased or reduced frictional locking
Implementation Method 2
The wrap spring brake operates on the basis of increased or reduced frictional locking
Data Source
AI summary
Armrest device having an armrest part swivellably movable between an armrest position and a not-in-use position, having a base part arranged fixed in the vehicle and on which the armrest part is mounted swivellably movable about a swivel axis, and having a locking device for supporting the armrest part in at least one swivel position relative to the base part. The swivel axis is axially split into a base axis section and an armrest axis section, and the locking device includes a wrap spring brake which interacts with the base axis section and the armrest axis section in order to release the armrest part during a swivel movement in the direction of the not-in-use position and to lock it during a reverse swivel movement.