Train Seat Leg Structure with Deformable Fifth Strut

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Solution Overview

Problem

High-speed train passenger seats, when fixed to the floor, form rigid units that pose a significant risk of injury to passengers in the event of a crash due to their unyielding nature, and there is a risk of the seat being torn from its anchoring and thrown, potentially causing severe knee injuries from collisions with adjacent seats.

Innovation Solution

A rail vehicle passenger seat design featuring a strut device with a rectangular frame formed by four struts, where a fifth strut is coupled to the frame in a way that allows it to deform plastically under load, providing relative mobility and absorb impact forces, thus reducing the severity of injuries by allowing the seat to yield during collisions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the seat is designed as a rigid unit fixed to the floor, then structural stability and support are improved, but passenger safety in crash situations deteriorates due to unyielding collisions

Engineering Contradiction:
Improvestructural stabilityVSAvoidinjury risk
Core Design Contradiction:
Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The patent applies the dynamics principle by introducing a deformable fifth strut that can change its structural state during impact events. The strut transitions from a rigid supporting element to a deformable energy-absorbing component, allowing the seat to dynamically adapt to crash forces and reduce injury risks while maintaining normal structural stability during operation.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements parameter changes by modifying the fifth strut's physical properties - specifically its geometry (folded/wavy/curved/kinked configuration) and material characteristics - to enable plastic deformation under impact loads. This changes the strut's stiffness parameter from high (rigid) to low (deformable) during crashes, allowing energy absorption while maintaining structural integrity during normal use.

Inventive Principle:
Principle #35Parameter changes

2Strength

If the seat structure is made rigid to prevent tearing from floor anchoring, then structural integrity is improved, but knee injury risk from seat throwing deteriorates

Engineering Contradiction:
Improvestructural integrityVSAvoidknee injury risk
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent applies segmentation by dividing the foot structure into multiple independent struts (first through fifth struts) with different functional characteristics. The first four struts provide rigid structural support, while the fifth strut is segmented into deformable sections that can independently absorb impact energy, preventing the entire seat from being thrown while maintaining overall structural integrity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements local quality by assigning different mechanical properties to different parts of the foot structure. The fifth strut is specifically designed with folded/wavy/curved/kinked sections that enable localized plastic deformation, while the rest of the structure maintains rigidity. This localized deformability absorbs impact energy without compromising overall structural strength.

Inventive Principle:
Principle #3Local quality

3Object-affected harmful factors

If a deformable fifth strut is added to absorb impact energy, then passenger safety is improved, but device complexity increases

Engineering Contradiction:
Improveinjury severityVSAvoidstrut device complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent applies merging by integrating the fifth deformable strut into the existing four-strut foot structure as a unified rectangular frame. The fifth strut is coupled to the frame at coupling points that are part of the normal structural connections, combining the energy-absorbing function with the existing support structure rather than adding a separate, complex damping system.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent implements self-service by designing the fifth strut to automatically perform impact energy absorption through its own geometric configuration (folded/wavy/curved/kinked sections). The strut's shape enables self-deformation and energy dissipation without requiring external control systems, sensors, or active mechanisms, thereby adding safety functionality without proportionally increasing complexity.

Inventive Principle:
Principle #25Self-service

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 seat's deformable design reduces the risk and severity of injuries during crashes by allowing the seat to absorb impact forces, preventing further damage and injury from rigid collisions, and maintaining structural integrity.

Implementation Method 1

a flat bar which is designed in such a way that when a predetermined load acts on the frame, the at least one first region is stretched or lengthened, in particular with plastic deformation

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Data Source

PatentEP1854660B1Vehicle seat with a leg structure comprising impact energy absorbing elements
Publication Date: 2012.02.29 GRAMMER AG
  • EP1854660B1 patent drawingFigure 1
  • EP1854660B1 patent drawingFigure 2
  • EP1854660B1 patent drawingFigure 3

AI summary

The seat has a base (14) formed by a strut device (16), which is provided with struts (18, 20, 22, 24). The struts (18, 20) run horizontally, and the struts (22, 24) are coupled and held at a distance in a vertical direction, so that the four struts form a frame (26). A fifth strut (36) running inclined to a horizontal direction extends within the frame and is coupled with the frame in end regions (50, 52) of the strut (36). The fifth strut has a section (58), which runs in a foldable, corrugated or curved manner.