Suspension Damping Control at Maximum Extension

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Solution Overview

Problem

Existing suspension systems face a trade-off between damping force setting freedom and ride comfort, particularly at maximum extension, where increasing damping force to reduce impact can adversely affect comfort.

Innovation Solution

A suspension device that adjusts damping force based on stroke amount and acceleration, allowing for increased freedom in setting damping force without compromising ride comfort by increasing damping when there is a high likelihood of maximum extension.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If damping force is increased to reduce impact at maximum extension, then impact reduction is improved, but ride comfort deteriorates

Engineering Contradiction:
Improveimpact at maximum extensionVSAvoidride comfort
Core Design Contradiction:
Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The damping force is made dynamically adjustable based on real-time detection of suspension stroke amount and acceleration. The control unit increases damping force only when the suspension is detected to be in or near the maximum extension state with high acceleration, while maintaining lower damping force during normal operation to preserve ride comfort.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The damping force parameter is changed based on detected suspension conditions. The control unit modifies the damping force parameter upward when maximum extension is detected (based on stroke amount and acceleration thresholds) and maintains or reduces it during normal operation, allowing impact reduction only when necessary.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If damping force is increased to prevent maximum extension, then suspension control is improved, but degree of freedom in damping force setting is reduced

Engineering Contradiction:
Improvesuspension controlVSAvoiddegree of freedom in damping force setting
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The damping force setting is made dynamic rather than fixed, allowing the system to adapt between different damping force levels based on real-time suspension conditions. This enables the system to maintain high reliability when needed while preserving flexibility in normal operation.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The damping force parameter is adjusted based on detected conditions (stroke amount and acceleration). The control unit changes the damping force parameter from a fixed value to a variable value that adapts to suspension state, maintaining degree of freedom in setting while ensuring reliable control when maximum extension is detected.

Inventive Principle:
Principle #35Parameter changes

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

Enhances the ability to set damping force effectively while maintaining ride comfort by dynamically adjusting damping force according to the suspension's state, preventing excessive extension and minimizing impact on comfort.

Implementation Method 1

a damping device (200) which damps a force generated between a vehicle body (10) and wheels (2, 3)

Methodology Applied
Scientific EffectViscous damping: Viscous Damping

Implementation Method 2

a suspension spring (21s, 22s) provided inside the inner tube to elastically support the vehicle body

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3698999B1Suspension device
Publication Date: 2025.07.30 HITACHI AUTOMOTIVE SYST LTD
  • EP3698999B1 patent drawingFigure 1
  • EP3698999B1 patent drawingFigure 2
  • EP3698999B1 patent drawingFigure 3

AI summary

A suspension device includes a suspension including a damping device which damps a force generated between a vehicle body and a wheel, and a second setting unit (124) that increases a damping force of the damping device so as to be greater than the damping force generated when an acceleration (Ap) of change in a stroke amount is less than a predetermined value determined in advance, when the acceleration (Ap) of the change in the stroke amount is equal to or greater than the predetermined value, the stroke amount being an amount of displacement from a reference position of the wheel with respect to the vehicle body in an extension direction of the suspension.