Height-Adjustable Seat Safety Actuator for Rollover Head Clearance
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Solution Overview
Problem
Existing height-adjustable seat structures in trucks, lorries, and buses are prone to deformation and upward movement during a roll-over accident, posing a risk of head injury from the vehicle cab crossbeam due to insufficient coupling by seatbelts.
Innovation Solution
A safety arrangement using a seat actuator with a piston that forces the seat structure to a lowered position via a scissors-type mechanism, activated by a crash sensor, ensuring the seated person's body follows the seat downward, preventing head impact with the cab crossbeam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a belt retractor is used to restrict forward motion of the seat structure, then the seat structure's movement is restricted, but the belt requires slack that allows dangerous upward and lateral movement in roll-over accidents
Solution Approach 1:
The patent applies preliminary anti-action by using a crash sensor to detect roll-over accidents and trigger an actuator that actively pushes the seat structure downward to counteract the upward movement force. This preemptive measure opposes the harmful upward motion before it can cause head contact with the crossbeam, transforming the system from passive restraint to active counter-action.
Solution Approach 2:
The patent introduces an intermediary actuator mechanism between the seat structure and the floor. This actuator, activated by the crash sensor, serves as a mediator that applies downward force to the seat structure during roll-over accidents, bridging the gap between detection and protection, and eliminating the dangerous slack in the belt system.
2Ease of operation
If the seat is set to a vertically raised position for comfort, then ergonomic working environment is improved, but the vertical distance between the person's head and the crossbeam is reduced increasing injury risk
Solution Approach 1:
The patent applies dynamics by making the seat structure's vertical position adaptive rather than static. The actuator dynamically adjusts the seat position during roll-over accidents by forcing it downward, allowing the system to maintain comfort during normal operation while automatically responding to dangerous conditions, thus resolving the contradiction between fixed comfort settings and variable safety requirements.
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
Prevents head injury from the vehicle cab crossbeam by ensuring the seated person's body moves downward, with the seat actuator's force overriding the seat lifting mechanism, and allowing airbags to accommodate lateral head movement.
Implementation Method 1
move the first piston from a retracted position to an extended position in which it directly or indirectly exerts a force to one of the linearly movable end portions of the first set of legs, thereby forcing the height-adjustable seat structure towards a lowered position
Data Source
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AI summary
A safety arrangement for a height-adjustable seat structure (100) is provided. The seat structure comprises a first set of legs (101A) comprising a first leg (105A) pivotably connected to a second leg (108A), and a first pair of guide rails (102A) comprising an upper guide rail (103A) and a lower guide rail (104A). The first leg comprises one end portion (106A) being pivotably hinged to the upper guide rail and the other end portion (107A) being linearly movable along the lower guide rail. The second leg comprises one end portion (109A) being pivotably hinged to the lower guide rail and the other end portion (110A) being linearly movable along the upper guide rail. The seat structure further comprises a first seat actuator (200) comprising a first piston (202), said first seat actuator being configured to, upon an activation signal, move the first piston from a retracted position to an extended position in which it directly or indirectly exerts a force to one of the linearly movable end portions, thereby forcing the height-adjustable seat structure towards a lowered position. Also, a vehicle seat provided with such safety arrangement is disclosed.