Gas Pressure Spring for Coordinate Measuring Device

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Solution Overview

Problem

Existing coordinate measuring machines face challenges in maintaining a consistent bearing gap and spring force due to manufacturing-related deviations, such as parallelism errors and surface roughness, leading to instability and potential oscillation of fluid pressure bearings.

Innovation Solution

A coordinate measuring machine design featuring a gas pressure spring with a piston, pressure chamber housing, and rolling membrane, which maintains a constant spring force and allows for easy adjustment by varying gas pressure, ensuring the fluid pressure bearings are pressed against the guide with a defined force, independent of component deviations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a fluid pressure bearing is used with a conventional suspension system, then the bearing can be pressed against the guide, but manufacturing-related deviations (parallelism errors, surface roughness) cause variations in spring force and bearing gap, leading to instability and oscillation

Engineering Contradiction:
Improvestability of bearing gapVSAvoidsensitivity to manufacturing deviations
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies dynamics by making the suspension system adjustable. The gas pressure spring allows dynamic adjustment of the spring force to compensate for manufacturing deviations. By varying the gas pressure, the system can adapt to different bearing gaps and load conditions, transforming a static suspension into a dynamically adjustable one that maintains stable bearing operation despite manufacturing variations.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements parameter changes by allowing adjustment of the gas pressure in the spring. This changes the spring force parameter, enabling optimization of the bearing gap and stability. The ability to modify the pressure parameter compensates for manufacturing tolerances and maintains reliable bearing operation under varying conditions.

Inventive Principle:
Principle #35Parameter changes

2Strength

If the spring force is increased to reduce bearing gap, then bearing rigidity improves, but the bearing becomes sensitive to alternating loads and particles, causing contact and oscillation

Engineering Contradiction:
Improvebearing rigidityVSAvoidsensitivity to alternating loads and particles
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The adjustable gas pressure spring enables dynamic optimization of the spring force. Rather than using a fixed high spring force that causes sensitivity to disturbances, the system allows adjustment to the minimum necessary force for maintaining bearing rigidity, thereby reducing sensitivity to alternating loads and particles while still achieving stable bearing operation.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

By allowing continuous adjustment of the gas pressure parameter, the system can optimize the spring force to achieve the threshold where bearing rigidity is sufficient but sensitivity to harmful factors is minimized. This parameter adjustment capability resolves the contradiction between maintaining rigidity and avoiding excessive sensitivity.

Inventive Principle:
Principle #35Parameter changes

3Object-affected harmful factors

If the spring force is decreased to reduce sensitivity to disturbances, then bearing stability improves, but the bearing gap increases and oscillation may occur

Engineering Contradiction:
Improveresistance to alternating loadsVSAvoidbearing gap consistency
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The adjustable suspension system allows dynamic optimization of the spring force parameter. The gas pressure can be adjusted to achieve the precise balance point where the bearing is sufficiently compliant to resist alternating loads and particles, yet maintains a consistent bearing gap to prevent oscillation. This dynamic adjustability resolves the contradiction between compliance and gap consistency.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

By adjusting the gas pressure parameter, the system can find the optimal spring force that simultaneously achieves resistance to disturbances and maintains bearing gap consistency. The ability to modify this parameter allows the system to operate at the optimal point on the performance curve, resolving the contradiction.

Inventive Principle:
Principle #35Parameter changes

4Ease of manufacture

If conventional suspension systems are used, then manufacturing is relatively easy, but adjustment of spring force is difficult and time-consuming or impossible

Engineering Contradiction:
Improvesimplicity of suspension assemblyVSAvoidadjustability of spring force
Core Design Contradiction:
Ease of manufactureVSEase of operation

Solution Approach 1:

The patent employs pneumatics by using a gas pressure spring instead of conventional mechanical suspension elements. This allows the spring force to be adjusted simply by varying the gas pressure, which can be done easily and quickly without complex mechanical adjustments. The pneumatic system maintains manufacturing simplicity while dramatically improving operational adjustability.

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

The gas pressure spring enables easy parameter adjustment of the spring force through pressure control. Unlike mechanical suspensions that require disassembly and physical adjustment of components, the pneumatic system allows continuous and easy adjustment of the force parameter by controlling gas pressure, greatly improving ease of operation while maintaining manufacturing simplicity.

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

This design stabilizes the bearing gap and spring force, reducing the impact of manufacturing-related errors and allowing for easy adjustment, thereby enhancing the rigidity and accuracy of the coordinate measuring machine.

Implementation Method 1

A coordinate measuring machine design featuring a gas pressure spring with a piston, pressure chamber housing, and rolling membrane, which maintains a constant spring force and allows for easy adjustment by varying gas pressure

Methodology Applied
Scientific EffectGas pressure: Pressure Increase

Implementation Method 2

a fluid pressure bearing which interacts with the guide, the fluid pressure bearing being part of a bearing assembly

Methodology Applied
Scientific EffectFluid pressure bearing: Air Lubrication

Data Source

PatentEP3164666B1Coordinate measuring device
Publication Date: 2018.08.15 CARL ZEISS INDUSTRIELLE MESSTECHNIKE GMBH
  • EP3164666B1 patent drawingFigure 1
  • EP3164666B1 patent drawingFigure 2
  • EP3164666B1 patent drawingFigure 3

AI summary

The invention relates to a bearing assembly (59; 59') comprising a fluid pressure bearing (31; 31'), and a suspension (55; 55') having two regions which are spring-loaded relative to each other, wherein the fluid pressure bearing (31; 31') is fastened to a first region and the second region thereof is configured to be fastened to a bearing base body (21; 35; 57), characterized in that the suspension is a gas compression spring (55; 55'). The invention further relates to a coordinate measuring device on which the bearing assembly (59; 59') is used.