Deformable Support Element for Monotube Damper Friction

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Solution Overview

Problem

Monotube dampers with separating pistons experience negative damping or stick-slip effects due to high static friction forces caused by high initial pressure in the counter-pressure chamber, leading to reduced comfort and shorter service life due to increased material wear.

Innovation Solution

An elastically deformable support element is integrated into the separating piston, which acts as both a sealing and dynamic support element, providing additional support force dynamically based on pressure, allowing for lower initial pressure in the counter-pressure chamber and reducing frictional forces, thereby minimizing stick-slip and wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If high initial pressure is used in the counter-pressure chamber to absorb maximum forces during damping, then the damper can handle severe and short-term stress, but high static friction forces occur on the separating piston seal and piston rod seal, causing stick-slip effects and reduced service life

Engineering Contradiction:
Improveforce absorption capacityVSAvoidservice life
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The support force is segmented into two independent components: a static support force from the pre-compressed spring and a dynamic support force from the elastically deformable support element. This segmentation allows each component to address different aspects of the force requirements, enabling the system to handle maximum forces while reducing static friction.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The initial pressure in the counter-pressure chamber is reduced by introducing a dynamic support element that compensates for force variations. The support element's elasticity allows it to deform under pressure, dynamically adjusting the support force to match loading conditions, thereby maintaining force absorption capacity at lower static pressure levels.

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If high initial pressure is applied in the counter-pressure chamber, then the damper can compensate for volume changes and absorb maximum forces, but the separating piston experiences high static friction forces leading to stick-slip effects during short and fast damping processes

Engineering Contradiction:
Improvevolume compensationVSAvoiddamping response
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

The support element is designed to be elastically deformable, transforming the static support system into a dynamic one. The support element deforms in response to pressure changes, dynamically adjusting its support force to match the instantaneous loading conditions, thereby maintaining volume compensation while reducing static friction and improving damping response.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The elastically deformable support element acts as an intermediary between the counter-pressure chamber and the separating piston. It mediates the force transmission, allowing the system to maintain volume compensation through controlled deformation while reducing the direct static friction contact between the separating piston and housing.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Strength

If high initial pressure is used to ensure proper sealing and force absorption, then the damper functions correctly under severe stress, but the sealing elements experience increased wear due to high frictional forces

Engineering Contradiction:
Improvesealing effectivenessVSAvoidsealing element service life
Core Design Contradiction:
StrengthVSDuration of action of stationary object

Solution Approach 1:

The system transitions from high static pressure to lower static pressure with dynamic pressure supplementation. The elastically deformable support element maintains sealing effectiveness by deforming under load to provide necessary support force, while the reduced static pressure level decreases wear on sealing elements during normal operation.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The pre-compressed spring provides beforehand cushioning by maintaining a baseline support force that prevents excessive static friction. This preliminary support reduces the load on sealing elements before dynamic loads are applied, extending their service life while maintaining sealing effectiveness under severe stress.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 solution effectively reduces static friction, prevents stick-slip, and extends the service life of the monotube damper by providing a dynamic support force that adapts to damping needs, ensuring comfortable operation and longer component lifespan.

Implementation Method 1

an elastically deformable support element (36) is provided on the separating piston (18), which rests against an inner wall (38) of the housing (12) with a dynamic support function

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The base body (24) has a main channel (28) which establishes a flow connection between the working chamber (20) and the support element (36)

Methodology Applied
Scientific EffectPressure: Pressure Increase

Data Source

PatentEP3155288B1Dividing piston and single-tube damper
Publication Date: 2018.08.15 BAYERISCHE MOTOREN WERKE AG
  • EP3155288B1 patent drawingFigure 1~3
  • EP3155288B1 patent drawingFigure 4

AI summary

The invention relates to a dividing piston (18) for a single-tube damper (10), which dividing piston comprises at least one deformable supporting element (36) for lying against an inner housing wall (38) of the single-tube damper (10) and a main body (24) having at least one channel (28), which establishes a flow connection from a surface (34) of the main body (24) to the supporting element (36). The supporting element (36) is acted upon outward, in particular radially outward, when pressure is applied via the at least one channel (28). The invention further relates to a single-tube damper (10).