Gas Compression Spring Intermediate Piston Lubrication

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Solution Overview

Problem

Gas pressure springs face challenges in effectively lubricating the piston rod within the housing, leading to increased friction and an altered characteristic curve due to the limited lubricating effect of lubricants introduced into the pressure chamber.

Innovation Solution

The implementation of two intermediate pistons on the piston rod, which separate the pressure chamber from lubricant chambers, providing enhanced lubrication and sealing, ensuring the gas volume is maintained and lubricant is pressed into gaps between the piston rod and housing during displacement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If lubricant is introduced into the pressure chamber filled with compressed gas, then the piston rod is lubricated, but the characteristic curve of the gas pressure spring is influenced and the lubricating effect is limited

Engineering Contradiction:
Improvelubrication effectVSAvoidcharacteristic curve influence
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The pressure chamber is segmented from the lubricant chamber using an intermediate piston. This allows the lubricant to be applied to the piston rod in a separate lubricant chamber rather than mixing it with the compressed gas in the pressure chamber, thereby maintaining the characteristic curve of the gas pressure spring while still providing effective lubrication.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

An intermediate piston is introduced as a mediator between the pressure chamber and the lubricant chamber. This intermediate piston enables the transfer of lubrication benefit to the piston rod while preventing direct contact between the lubricant and the compressed gas, thus avoiding influence on the characteristic curve.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If lubricant is introduced into the pressure chamber, then the piston rod is lubricated, but the gas volume in the pressure chamber is not maintained

Engineering Contradiction:
Improvelubrication effectVSAvoidgas volume
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The pressure chamber is segmented from the lubricant chamber using an intermediate piston. This segmentation prevents lubricant from entering the pressure chamber, thereby maintaining the gas volume and pressure characteristics while still providing lubrication to the piston rod through the separate lubricant chamber.

Inventive Principle:
Principle #1Segmentation

3Productivity

If friction between piston rod and housing is reduced, then the gas pressure spring performance is improved, but the piston rod requires additional lubrication measures

Engineering Contradiction:
Improvegas pressure spring performanceVSAvoidlubrication system
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The lubrication function is merged with the sealing function by using the intermediate piston to create a lubricant chamber that also serves as a seal for the pressure chamber. This combined approach reduces friction between the piston rod and housing while avoiding the need for separate, complex lubrication systems.

Inventive Principle:
Principle #5Merging (Combining)

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 configuration achieves improved lubrication and sealing, maintaining the gas volume and reducing friction, thereby enhancing the performance and longevity of the gas pressure spring and clamping devices.

Implementation Method 1

a pressure chamber (32) filled with compressed gas for generating a compressive force that acts on the piston rod (2)

Methodology Applied
Scientific EffectCompressed gas pressure: Pressure Increase

Implementation Method 2

Due to the lubricant chambers (26, 29) filled with a lubricant, in addition to a simple and effective lubrication of the piston rod (2)

Methodology Applied
Scientific EffectLubrication: Lubrication

Implementation Method 3

the pressure chamber (32) is sealed off from the outside on both sides by the intermediate pistons (19, 20) and the lubricant chambers (26, 29) filled with lubricant

Methodology Applied
Scientific EffectSealing: Physical Containment

Implementation Method 4

the intermediate pistons, which are movable relative to the piston rod, also put the lubricant in the lubricant chambers under pressure, whereby the lubricant is pressed into the gaps between the piston rod and the housing

Methodology Applied
Scientific EffectPressure-driven fluid movement: Pressure Gradient

Data Source

PatentEP2286944B1Gas compression spring and tensioning device with such a gas compression spring
Publication Date: 2012.10.03 OTT JAKOB & SPANNTECHN
  • EP2286944B1 patent drawingFigure 1
  • EP2286944B1 patent drawingFigure 2

AI summary

The spring has a displaceably guided piston rod (2) and a pressure chamber (32) arranged inside a housing (1), where the pressure chamber is filled with pressure gas. Two intermediate pistons (19, 20) are arranged on the piston rod. The pressure chamber is separated from two lubricant chambers (26, 29) by the intermediate pistons, where the lubricant chambers are filled with lubricant. Axial displacement of the intermediate pistons relative to the piston rod is limited by two retaining rings (33, 34). An independent claim is also included for a clamping device for clamping a tool or tool holder in a machine spindle of a tool machine.