Adjustable Damping Valve Return Body Radial Fixation

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Solution Overview

Problem

Adjustable damping valve devices experience noise issues due to sudden pressure fluctuations, flow noises, and rattling, primarily caused by hydraulic and mechanical factors, with no prior solution for the latter.

Innovation Solution

The PWM frequency of the coil control is aligned with the natural frequency of the piston rod, and the return body is fixed radially within the valve housing using a press fit, cone connection, or adhesive connection to prevent radial movement, thereby eliminating rattling noises by ensuring the return body vibrates at its natural frequency and is synchronized with the valve housing mass.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the return body is fixed radially without play in the valve housing, then rattling noises are eliminated and reliability is improved, but the device complexity increases due to additional press fit features

Engineering Contradiction:
Improvenoise eliminationVSAvoidstructural complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The return body is divided into functional zones: a press fit section with lateral surface for radial fixation, and a bottom surface for axial positioning. This segmentation allows the return body to be fixed radially without play while maintaining simplicity through geometric design rather than additional components.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The press fit is achieved through a conical connection between the return body and valve housing, using curved surfaces to provide self-centering and radial fixation. The conical geometry naturally guides the return body into proper alignment and eliminates radial play without requiring complex mechanical fastening mechanisms.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Object-affected harmful factors

If the return body forms a press fit with the valve housing, then radial movement is prevented and noise is reduced, but manufacturing precision requirements increase

Engineering Contradiction:
Improvenoise reductionVSAvoidpress fit tolerance
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The press fit connection utilizes a conical geometry with specific angle parameters that provide self-locking capability. By optimizing the cone angle and dimensional parameters, the design achieves reliable radial fixation with standard manufacturing tolerances, reducing the need for ultra-precise machining while eliminating rattling noises.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If the return body is loosely fitted with gap to valve housing, then assembly is easier and manufacturing is simpler, but magnetostriction causes vibration and rattling noise occurs

Engineering Contradiction:
Improveassembly easeVSAvoidrattling noise
Core Design Contradiction:
Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The return body is designed with an integrated press fit structure that performs the radial fixation action during assembly itself. The conical press fit geometry automatically centers and secures the return body radially as it is installed, eliminating the need for separate fastening operations while preventing magnetostriction-induced vibrations and rattling noises.

Inventive Principle:
Principle #10Preliminary action

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

This solution effectively reduces or eliminates rattling noises by ensuring the return body's vibrations are harmonized with the system's natural frequency, preventing the transmission of unwanted vibrations to the piston rod and thus minimizing noise generation.

Implementation Method 1

An actuator 13 with a coil arrangement 15 generates a magnetic force with which it acts on an armature 19

Methodology Applied
Scientific EffectElectromagnetic force: Lorentz Force

Implementation Method 2

Magnetostriction causes the return body to vibrate radially. This effect is intensified if the return body is slotted and thus has good elasticity in this area

Methodology Applied
Scientific EffectMagnetostriction: Magnetostriction

Implementation Method 3

the return body 17 forms a press fit 35 with an inner wall 33 of the valve housing 23

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3440376B1Adjustable damping valve device for a vibration damper
Publication Date: 2020.04.22 ZF FRIEDRICHSHAFEN AG
  • EP3440376B1 patent drawingFigure 1
  • EP3440376B1 patent drawingFigure 2~4
  • EP3440376B1 patent drawingFigure 5~6

AI summary

The invention relates to a damping valve device comprising at least one damping valve that can be adjusted via an actuator, wherein the actuator comprises a coil and a return body, which is separate to a valve housing, for a magnetic flux circuit, wherein the return body is fixed without play in the radial direction within the valve housing.