Pneumatic Plug Gauge for Tilt Angle Measurement

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Solution Overview

Problem

Current methods for high-precision angle measurement in technical systems, such as conical or cylindrical bores, are either inaccurate, costly, or too time-consuming for mass production, especially when using tactile or optical systems, and do not guarantee precise opening angles due to the lack of automatic geometry control during manufacturing processes like laser drilling or grinding.

Innovation Solution

A pneumatic measuring mandrel with a first and second outlet, connected to a pressure medium source, measures the tilting angle by determining the pressure changes in the measuring channel caused by the workpiece surface, allowing for precise angle determination with submicrometer accuracy and automatic elimination of contaminants, and can be designed to fit small bores and measure angles between 0° and 179°.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If tactile measurement systems are used for angle measurement, then mechanical contact can be established with the workpiece, but the workpiece surface is damaged and measurement accuracy is reduced

Engineering Contradiction:
Improvemeasurement reliabilityVSAvoidmechanical damage to workpiece
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the tactile mechanical measurement system with a pneumatic measurement system. Instead of using physical contact probes that mechanically interact with the workpiece surface, the invention uses compressed air streams that flow parallel to the surface without contact. The angle is determined by measuring the pressure distribution of the non-contacting air stream, thereby eliminating mechanical damage while maintaining measurement reliability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces compressed air as an intermediary medium between the measurement system and the workpiece. The air stream acts as a mediator that carries measurement information without directly contacting the workpiece surface. By measuring the pressure characteristics of this intermediary air stream, the system obtains angle information without causing mechanical damage to the measured object.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If optical measurement systems are used for high-precision angle measurement, then measurement accuracy can be improved, but the system becomes expensive and time-consuming

Engineering Contradiction:
Improveangle measurement precisionVSAvoidmeasurement speed for mass production
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent employs pneumatic principles to achieve high-precision angle measurement. By using compressed air streams and measuring the resulting pressure distribution with simple pressure sensors, the system attains optical-level precision without the complexity and cost of optical systems. The pneumatic method enables rapid measurement suitable for mass production while maintaining sub-degree angle measurement accuracy.

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

The patent replaces expensive optical measurement components with inexpensive pneumatic components such as air nozzles and pressure sensors. The measurement system uses readily available pneumatic parts that are much cheaper than optical systems, enabling cost-effective high-precision measurement for mass production applications.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Measurement precision

If optical measurement systems are used for angle measurement, then measurement accuracy can be achieved, but the system requires large space and high cost

Engineering Contradiction:
Improveangle measurement precisionVSAvoidsystem space requirement and cost
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent substitutes complex optical measurement systems with a compact pneumatic system. Instead of requiring optical benches, lasers, and interferometers that occupy large spaces, the invention uses a simple pneumatic probe with air nozzles and pressure sensors. This mechanical-to-pneumatic substitution dramatically reduces system footprint and cost while maintaining measurement precision.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Measurement precision

If conventional measurement methods are used for contaminated surfaces, then measurement can proceed, but accuracy is drastically distorted by contaminants

Engineering Contradiction:
Improveangle measurement precisionVSAvoidcontaminant interference
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent uses the pneumatic air stream to automatically blow away contaminants from the measurement area. The compressed air not only serves as the measurement medium but also acts as a cleaning agent that removes oil, dust, and other contaminants from the workpiece surface, ensuring accurate measurements even in contaminated environments.

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

The measurement system performs self-cleaning by using its own pneumatic air stream to remove contaminants from the measurement area. The same compressed air that carries measurement information also cleans the surface, eliminating the need for separate cleaning operations and ensuring continuous measurement accuracy.

Inventive Principle:
Principle #25Self-service

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

Enables high-precision angle measurements with submicrometer accuracy and rapid processing, suitable for mass production, reducing mechanical damage and operational costs, and allowing for seamless quality control by converting pneumatic length measurement precision into angle measurement precision.

Implementation Method 1

By simultaneously or alternately pressurizing both outlets with the pressure medium, the distances between the first outlet and the area opposite it on the workpiece surface, as well as between the second outlet and the workpiece surface opposite it, can be determined.

Methodology Applied
Scientific EffectPressure medium flow:

Implementation Method 2

The pressure in the measuring channel can be measured as a measure of the respective distance between the outlet and the workpiece surface.

Methodology Applied
Scientific EffectPressure change measurement:

Data Source

PatentEP3230687B1Pneumatic plug gauge and measuring method
Publication Date: 2020.07.01 ROBERT BOSCH GMBH
  • EP3230687B1 patent drawingFigure 1

AI summary

A pneumatic plug gauge has been developed in the context of the invention. This plug gauge comprises a first measuring channel which can be connected to a pressure medium source and opens into a first outlet for the pressure medium, which outlet can be directed to a surface of the workpiece to be tested. According to the invention, this plug gauge is designed to determine the tilt angle between a section on the surface thereof and a region opposite this section on the surface of the workpiece by virtue of the first outlet being arranged at one end of the section and at least one second outlet being provided, which second outlet is arranged at the other end of the section. It has been recognized that the admittedly high precision of pneumatic length measurements can be converted in a particularly advantageous manner to high precision of the angle measurement in this manner. The tilt angle can be measured at least with an accuracy of less than one tenth of a degree. At the same time, the measurement is fast enough for 100% control in mass production. The plug gauge is the central element in the measuring system and in the method, to which the invention likewise relates.