Aircraft Seat Multi-Link Hinge Virtual Axis Design
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Solution Overview
Problem
Aircraft seat convertible to a bed designs face challenges in maintaining comfort and preventing upholstery gaps or collisions during conversion, particularly due to conventional hinge mechanisms that can be intrusive and uncomfortable.
Innovation Solution
The implementation of a multi-link linkage providing a virtual hinge axis spaced not below the links themselves, combined with duplicated linear runners and tandem-driven belts for smooth movement, and a lead screw actuator for reclining and elevating the seat pan and backrest, ensures a more comfortable and gap-free conversion process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional hinge mechanism is used to connect the backrest support to the pan, then the structure is simple and easy to manufacture, but the hinge axis becomes intrusive and causes upholstery gaps or collisions, reducing comfort
Solution Approach 1:
The patent relocates the hinge axis from a conventional position to one spaced behind the pan-reclining axis, utilizing a different spatial dimension. This repositioning allows the hinge mechanism to operate in a plane that prevents upholstery interference while maintaining structural simplicity.
Solution Approach 2:
The patent introduces an intermediary hinge axis positioned between the pan-reclining axis and the backrest movement path. This intermediate hinge serves as a mediator that coordinates the movement of both the pan and backrest, preventing direct collision and gap formation while preserving manufacturing ease.
2Device complexity
If a single hinge mechanism is used for both pan and backrest movement, then the device complexity is reduced, but the movement profile is harsh and causes tugging on clothes
Solution Approach 1:
The patent segments the movement control into two independent hinge mechanisms: one for pan reclining and another spaced behind it for backrest movement. This segmentation allows each hinge to provide a smooth, independent movement profile, eliminating the harsh tugging effect of a single combined hinge while maintaining reasonable device complexity.
Solution Approach 2:
By positioning the second hinge axis in a different spatial dimension (spaced behind the first axis), the patent creates independent movement paths for the pan and backrest. This dimensional separation allows both components to move smoothly without mechanical interference, improving operational comfort.
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 comfort by reducing the tendency to tug at clothes during conversion and eliminates hard points at the edges of the bed, providing a flatter structure and improved movement profile, thus improving the overall user experience in both seat and bed configurations.
Implementation Method 1
a seat frame sub-frame mounted via rolling element bearings on the linear runners
Implementation Method 2
linear drive means for extending (and retracting) the sub-frame on the runners with respect to the seat chassis
Implementation Method 3
the hinge is a multi-link linkage providing a virtual hinge axis spaced not below the links themselves
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An aircraft seat has a chassis (21), fixed to a pallet which is fixed to the floor of the aircraft. The chassis has two load bearing sides (23) and opposite ends (24, 25). Fixed along the top edge of the sides (23) and facing outwards are pins (26) supporting bearing wheels (27). These on each side engage with a rectangular S form interconnection beam (28) having an inside groove (29) for receiving these wheels. On the outside, the beam has another groove (30) receiving similar wheels (31), on pins (32) fixed to the inside of side plates (41) of a sub-frame (42), these side plates being interconnected by front and rear beams (43, 44). Thus the sub-frame can move back and forth, with the wheels acting as rolling element bearings. The beams move half the distance of the sub-frame, in analogous manner to the bearing of filing cabinet drawers. At both sides of the chassis and sub-frame drive belts (33) are arranged. They run around front and back guide pulleys (34), pinch pulleys (35) and drive pulleys (36). The pinch pulleys can release their grip on the belt for emergency manual movement of the sub-frame. The drive pulleys are provided at opposite ends of drive shaft (37), journalled at its ends in the side plates and connected between the drive pulleys (36) to a drive motor (38). The belts are endless and are clamped by clamps (45) to the rear beam (44) of the sub-frame. Operation of the motor thus drives the sub-frame forwards or backwards with respect to the chassis and the seat pallet (22).