Seat Backrest Coupling Assembly With Self-Locking Tensile Preload
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing connection arrangements for attaching a backrest support to a seat support in seating furniture, such as office swivel chairs, are cumbersome to assemble and require additional tools or assistance, with potential issues of loose or stuck clamping screws due to material creep or corrosion, and are not aesthetically pleasing.
Innovation Solution
A connection arrangement featuring a coupling shaft, coupling extension, and coupling element with a suspension and insertion extension that uses tensile stress to self-lock the coupling extension in the shaft, allowing for tool-free assembly and concealed fastening, reducing assembly complexity and increasing design appeal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a clamping screw is used to attach the backrest to the seat support, then the assembly can be performed manually, but the screw may unintentionally loosen over time due to material creep or corrosion
Solution Approach 1:
The connection arrangement is designed to be self-assembling through the interaction of the coupling element's geometry and the tensile force applied during attachment. The coupling element automatically engages with the coupling shaft and coupling extension, creating a self-locking mechanism that eliminates the need for separate fastening operations and prevents loosening over time.
Solution Approach 2:
The coupling element is pre-configured with specific geometric features (coupling groove, coupling bolt engagement surfaces) that prepare the connection for automatic self-locking. The tensile force is applied in advance during the attachment process, creating preliminary compression that prevents subsequent loosening due to material creep or corrosion.
2Reliability
If a solid screw connection is used to attach the backrest support to the seat support, then the design is more attractive and safer, but mounting requires a second fitter or special holding device
Solution Approach 1:
The coupling element combines multiple functions into a single component: it provides the attachment interface, applies the tensile force, and creates the self-locking mechanism all in one piece. This integration eliminates the need for separate fastening operations and reduces assembly complexity from requiring multiple people to a single-person operation.
Solution Approach 2:
The connection arrangement is designed to be self-assembling through the interaction of the coupling element's geometry and the tensile force applied during attachment. The coupling element automatically engages with the coupling shaft and coupling extension, creating a self-locking mechanism that eliminates the need for separate fastening operations and prevents loosening over time.
3Ease of operation
If a clamping screw with large dimensions is used, then it is easier to handle, but it is not advantageous from a design point of view
Solution Approach 1:
The visible clamping screw is completely removed from the design. The attachment mechanism is extracted and replaced with a concealed coupling system where the coupling element engages with the coupling shaft and coupling extension internally. This eliminates the aesthetic drawback of visible fasteners while maintaining ease of operation through the self-assembling mechanism.
Solution Approach 2:
The coupling element serves as an intermediary that provides the necessary attachment function without being visible from the outside. It mediates between the coupling shaft and coupling extension, creating a concealed fastening system that maintains clean design appearance while providing secure attachment.
4Reliability
If multiple screws are used to attach the backrest support, then the connection is more secure, but the assembly work increases leading to higher assembly costs
Solution Approach 1:
Multiple fastening functions are merged into a single coupling element that performs attachment, force application, and self-locking simultaneously. This consolidation reduces the number of discrete assembly steps from multiple screw operations to a single self-assembling action, dramatically improving assembly speed while maintaining connection security.
Solution Approach 2:
The coupling element is designed to self-assemble through its geometric interaction with the coupling shaft and coupling extension. The self-locking mechanism automatically engages when tensile force is applied, eliminating the need for multiple fastening operations and reducing assembly time while ensuring secure connection.
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
Enables easy, safe, and quick assembly by a single person, with the tensile preload compensating for any play over time, and allows for volume-optimized transport and assembly at various locations, including home or sales points, enhancing usability and cost-effectiveness.
Implementation Method 1
there is a tensile stress between the suspension extension and insertion extension, which causes the coupling extension in the coupling shaft holds and keeps the insertion extension self-locking in the coupling groove
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
The arrangement (1) has a coupling shaft (2), and a coupling projection (3) inserted into the shaft in a mounted condition. A coupling bolt (4) is fastened to the projection, and a coupling groove (5) is formed within the shaft. A coupling element (6) has a hanging projection (7) and an insertion projection (8). The coupling element, groove and bolt are arranged such that tensile stress lies between the hanging and insertion projections in the mounted condition for holding the coupling projection in the shaft and for holding the insertion projection in the groove in a self-locking manner. Independent claims are also included for the following: (1) a seat furniture (2) a mounting method for connecting a back carrier to a seat support.