Vehicle Seat Backrest Pivot Axis Shift for Upper Back Support
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Solution Overview
Problem
Vehicle seats in commercial vehicles, such as tractors and forklifts, often lack adequate support for the upper back when the backrest is tilted backwards, leading to discomfort and inadequate shoulder joint support, especially for drivers who need to assume a working position facing upwards.
Innovation Solution
A vehicle seat design where the backrest element is pivotable about an axis of rotation shifted rearward, resulting in an upward displacement of the contact surface, ensuring a minimum distance of 60mm to support the upper back, with an angle of inclination of 10°, and optionally featuring a scissor frame arrangement, spring and damping devices, and a locking mechanism for adjustable inclination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the backrest element is made short to allow greater freedom of movement and upward working position, then the driver's freedom of movement is improved, but the support for the shoulder joint point deteriorates
Solution Approach 1:
The invention shifts the axis of rotation from a conventional position to a rearward position, changing the dimensional relationship between the backrest and occupant. This rearward shift creates a geometric configuration where the upper edge of the backrest extends higher, providing shoulder joint support without increasing the overall backrest length, thus maintaining freedom of movement while adding support functionality.
Solution Approach 2:
The invention changes the parameter of axis of rotation position along the longitudinal axis, specifically shifting it rearward by a distance A of at least 60mm. This parameter change fundamentally alters the backrest's geometry during tilting, causing the upper edge to reach higher positions and provide adequate shoulder joint support while keeping the backrest short for mobility.
2Ease of operation
If the backrest element is tilted backwards for resting or upward working position, then the driver's comfort is improved, but the contact surface position becomes inadequate for supporting the upper back
Solution Approach 1:
By shifting the axis of rotation rearward, the invention changes the dimensional trajectory of the contact surface during tilting. The contact surface follows a different arc that maintains higher vertical position relative to the occupant's back, ensuring adequate upper back support in both upright and tilted positions while improving comfort.
3Device complexity
If the axis of rotation is positioned conventionally, then the backrest structure is simple, but the upper edge of the backrest does not reach sufficient height to support the shoulder joint point
Solution Approach 1:
The invention modifies the parameter of axis of rotation position, shifting it rearward by distance A ≥ 60mm. This single parameter change transforms the backrest's effective height during tilting without adding structural complexity, allowing the upper edge to reach the shoulder joint point while maintaining a short backrest design.
Solution Approach 2:
The rearward shift of the axis of rotation creates a different spatial relationship between the backrest and occupant. This dimensional change allows the backrest to achieve greater vertical reach during tilting through geometric configuration rather than increased physical length, maintaining structural simplicity.
Data Source
Figure 1~2
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Figure 5~6b
AI summary
The invention relates to a vehicle seat comprising a backrest element with a first contact surface arranged within a first fictitious plane and a seat element with a second contact surface arranged within a second fictitious plane spanned by a longitudinal axis (X) and a transverse axis (Y) of the vehicle seat, wherein the first fictitious plane and the second fictitious plane intersect at a sectioning axis (SR), wherein the backrest element is pivotable relative to the seat element about a rotational axis (RD), wherein an angle of inclination (a) of the backrest element extends between the first fictitious plane and a central axis (M) which runs perpendicular to the second fictitious plane, wherein in a first position of the backrest element a distance along the longitudinal axis (X) between the rotational axis (RD) and the sectioning axis (SR) is at least 60 mm.wherein in the first position of the backrest element the angle of inclination (a) is essentially 10°.