Chair Top Board Pivot Locking for Stable Vertical Folding
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Solution Overview
Problem
Conventional pivotable top board devices for chairs lack stability during unfolding and folding operations, leading to deviation of the top board from the vertical position and increased friction and wear.
Innovation Solution
A pivotable top board device with an armrest, axle block, and coupling board, featuring a positioning device with an operation rod and elastic element, which ensures secure engagement between the axle block and armrest, preventing rotation during folding and unfolding, and maintaining the top board's vertical position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional pivotal arrangement is used between the axle block and coupling board, then the top board can be folded into the receiving space, but the axle block is apt to pivot during folding operation leading to deviation of the top board from the vertical direction
Solution Approach 1:
The positioning device with operation rod and elastic element performs preliminary positioning action before the folding operation completes. The elastic element pre-loads the operation rod to engage with positioning holes at appropriate timing, preventing unwanted pivoting of the axle block during the folding process and maintaining the top board's vertical position.
Solution Approach 2:
The operation rod acts as an intermediary element between the axle block and the positioning system. It transmits the positioning force from the elastic element to control the angular position of the axle block, ensuring stable folding operation without direct rigid connection that would constrain movement.
2Ease of operation
If the top board deviates from vertical position during folding, then readjustment is required, but this causes friction and wear between the top board edge and armrest surface
Solution Approach 1:
The positioning device performs preliminary action by engaging the operation rod with positioning holes at the correct angular position before the top board contacts the armrest. This prevents deviation and eliminates the need for readjustment, thereby avoiding friction and wear between the top board edge and armrest surface.
Solution Approach 2:
The elastic element provides continuous feedback force on the operation rod to maintain proper angular positioning. When the top board approaches the folded position, the elastic element's pre-load ensures the operation rod engages with the positioning hole at the optimal moment, preventing contact between the top board and armrest that would cause wear.
3Adaptability or versatility
If the operation rod length is larger than the through-hole length, then the operation rod can engage with both positioning holes sequentially, but the operation rod must move significantly along the longitudinal axis
Solution Approach 1:
The positioning function is segmented into two distinct positions represented by two separate positioning holes. The operation rod engages with the first positioning hole during unfolding and with the second positioning hole during folding, allowing the rod to move along its longitudinal axis to accommodate both positions while maintaining engagement capability.
Solution Approach 2:
The operation rod is designed to be dynamically movable along the longitudinal axis of the through-hole. This dynamic movement allows the rod to transition between engaging the first positioning hole and the second positioning hole, adapting to different operational states (unfolding vs. folding) while the elastic element provides continuous positioning force.
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 enhances stability and reduces friction and wear by maintaining the top board's vertical position during operations, allowing for smooth and secure unfolding and folding without readjustment.
Implementation Method 1
an elastic element provided in the through-hole and having elasticity for moving the operation rod
Data Source
AI summary
A pivotable top board device for a chair includes an armrest having a coupling face with a first positioning hole. An axle block includes a first coupling face and a second coupling face. The first coupling face of the axle block is pivotably coupled to the coupling face of the armrest. The axle block further includes a through-hole extending from the first coupling face through the second coupling face. An operation rod longer than the through-hole is received in the through-hole and includes a first positioning end for disengagably engagement with the first positioning hole of the armrest and a second positioning end. The second coupling face of the axle block is pivotably coupled to a coupling face of a coupling board fixed to a top board. The coupling face of the coupling board includes a second positioning hole releasably receiving the second positioning end of the operation rod.