Shiftable-Pivot Recliner Mechanism for Zero Rear Clearance
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Solution Overview
Problem
Standard reclining chair mechanisms require rear clearance due to the rearward shift of the backrest when reclined, limiting the ability to achieve true zero-clearance and increasing user effort to operate the chair.
Innovation Solution
A reclining chair mechanism with a shiftable pivot mechanism, including a follower post and slot or linkage, allows the front swing link to pivot relative to the base link, reducing the rearward movement of the backrest and enabling easier operation by shifting the pivot point, thus minimizing rear clearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the front swing link is made longer than the rear swing link to achieve rearward seat slope, then user comfort is improved, but user effort to operate the chair increases excessively
Solution Approach 1:
The patent employs a shiftable pivot mechanism that dynamically changes the pivot point position of the front swing link during recline operation. The pivot shifts from a first position in the upright configuration to a second position in the reclined configuration, allowing the mechanism to adapt its geometry throughout the motion range. This dynamic adjustment enables the seat to achieve the desired rearward slope while keeping user operating effort within acceptable limits, as the pivot shift optimizes the mechanical advantage during different phases of operation.
2Length of moving object
If the difference in length between front and rear swing links is increased to achieve greater forward shifting of the seat, then zero-clearance performance is improved, but user effort to operate the chair becomes excessively high
Solution Approach 1:
The shiftable pivot mechanism dynamically adjusts the effective length and position of the front swing link during operation. By shifting the pivot from a first position to a second position as the chair reclines, the mechanism achieves greater forward shifting of the seat and improved zero-clearance performance without requiring an excessively large fixed length difference between swing links. This dynamic geometry change optimizes the balance between clearance performance and operating effort throughout the recline range.
3Ease of manufacture
If standard reclining mechanisms are used, then ease of manufacture is improved, but rear clearance requirement increases
Solution Approach 1:
The patent introduces a shiftable pivot mechanism that changes the pivot position of the front swing link during recline operation. This dynamic adjustment causes the lower edge of the backrest and seat to shift forward relative to the floor as the chair reclines, thereby reducing the rearward shift of the top edge of the backrest. This enables the mechanism to achieve zero-clearance or minimal clearance performance while maintaining reasonable manufacturing complexity through the use of standard linkage components combined with the pivot shift feature.
Data Source
AI summary
A reclining chair includes a seat, a backrest, and a pair of spaced apart recliner mechanisms cooperatively supporting the seat and backrest. Each of the mechanisms includes a ground engaging base link, a seat link operably coupled with and supporting the seat, a backrest linkage operably coupling the backrest to the seat link, a rear swing link operably coupled to the base link at a first pivot, and a front swing link operably coupled to the base link with a shiftable pivot mechanism defining a second pivot. The rear swing link and the front swing link are selectively pivotable about the first and second pivots respectively to enable the mechanism to be selectively shifted between an upright position and a reclined position. The shiftable pivot mechanism shifts a position of the second pivot relative to the base link as the mechanism shifts between the first position and the second position.