Vehicle Seat Damping Control via Position-Dependent Force

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Solution Overview

Problem

Conventional vehicle seat damping systems face challenges in effectively managing vibrations and impacts, leading to discomfort and potential health issues due to end stops and inefficient damping at different stages of spring travel, especially in off-road vehicles.

Innovation Solution

A controllable damping system for vehicle seats that adjusts damping force based on the total damping path, user-specific settings, and movement direction, using electro- or magnetorheological dampers, to provide optimal damping across the available spring travel and prevent end stops, with adjustable damping forces set by a control device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a purely speed-dependent passive or controlled damper is used, then the damping force can be adjusted based on movement speed, but the available spring travel is not fully utilized and end stops cannot be avoided

Engineering Contradiction:
Improvedamping forceVSAvoidspring travel
Core Design Contradiction:
ForceVSLength of moving object

Solution Approach 1:

The patent applies parameter changes by transitioning from a purely speed-dependent damping force to a position-dependent damping force. The control device adjusts the damping element's parameter (damping force) based on the measured position of the upper part relative to the lower part, allowing the damper to adapt to the available spring travel and prevent end stops while fully utilizing the damping path.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the damping system is designed for the worst case to avoid every stop, then no end stops occur, but the setting is felt to be too hard

Engineering Contradiction:
Improveend stop avoidanceVSAvoidseating comfort
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent applies dynamics by making the damping force dynamically adjustable based on the current position of the upper part. Instead of a fixed hard setting, the control device continuously adapts the damping element's force characteristic according to the measured position, providing soft damping when spring travel is available and preventing end stops only when necessary, thus optimizing both reliability and comfort.

Inventive Principle:
Principle #15Dynamics

3Reliability

If travel-dependent passive dampers create harder damping at the end of spring travel, then end stops are prevented, but the damping is inefficient and uncomfortable during springback when sufficient spring travel is available

Engineering Contradiction:
Improveend stop preventionVSAvoiddamping efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies feedback by using a sensor device to measure the current position of the upper part and feeding this information back to the control device. The control device then adjusts the damping element's force characteristic based on this feedback, allowing the system to distinguish between compression phases (where end stop prevention is needed) and rebound phases (where soft damping is preferred), thereby optimizing damping efficiency while maintaining reliability.

Inventive Principle:
Principle #23Feedback

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 system enhances seating comfort by maintaining a consistent damping force within a comfort range, preventing end stops, and reducing resonance effects, thereby improving the overall damping performance and reducing the risk of health issues associated with prolonged exposure to vibrations.

Implementation Method 1

at least one through a control device controllable damping element (6) is provided

Methodology Applied
Scientific EffectElectro- or magnetorheological damping: Electrorheological Effect

Implementation Method 2

using electro- or magnetorheological dampers

Methodology Applied
Scientific EffectMagnetorheological damping: Magnetorheological Fluid

Data Source

PatentEP3238984B1Variable damping system for a vehicle seat
Publication Date: 2019.12.18 GRAMMER AG
  • EP3238984B1 patent drawingFigure 1
  • EP3238984B1 patent drawingFigure 2a~2c
  • EP3238984B1 patent drawingFigure 3~4

AI summary

The invention relates to an adjustable damping system for a vehicle seat for damping a movement of a seat-side upper part relative to a body-side lower part in at least one spatial direction (X, Y, Z), wherein at least one damping element is provided between the seat-side upper part and the body-side lower part, which can be adjusted by a control device.The damping system is further characterized by the fact that a first damping force of the damping element is adjustable by the control device, wherein this first damping force can be determined by the control device on the basis of a total damping path of the damping element, a basic damping force preset by a damping adjustment device, a position of the seat-side upper part relative to the body-side lower part measurable by a sensor device and a direction of movement of the seat-side upper part relative to the body-side lower part, wherein the direction of movement can be determined from at least two temporally successive positions of the seat-side upper part relative to the body-side lower part measurable by the sensor device.