Pneumatic Position Sensor for Swivel Clamp Piston Rod

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Solution Overview

Problem

Conventional pneumatic position queries in swivel clamps require additional space and are complex due to moving parts, increasing the axial length and susceptibility to errors.

Innovation Solution

A pneumatic position query system with control elements, such as annular grooves and recesses on the piston rod, that pneumatically determine the axial and rotational positions of the piston rod without moving parts, using supply and exhaust air ducts to detect position changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If pneumatic valves are used for position sensing, then position detection is achieved, but the axial length of the swing clamp increases

Engineering Contradiction:
Improveposition detectionVSAvoidaxial length
Core Design Contradiction:
Measurement precisionVSLength of stationary object

Solution Approach 1:

The patent combines the position sensing function with the existing piston rod structure by integrating control elements (annular grooves and recesses) directly onto the piston rod surface. This merging eliminates the need for separate pneumatic valves, thereby detecting position without increasing axial length.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The piston rod serves multiple functions: it provides mechanical movement and simultaneously acts as the sensing element for position detection through its integrated control elements. This multi-functionality removes the need for dedicated sensing components that would increase axial length.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Measurement precision

If pneumatic valves with moving parts are used, then position sensing is achieved, but the device complexity and susceptibility to errors increase

Engineering Contradiction:
Improveposition sensingVSAvoidcomplexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the moving parts from the traditional pneumatic valve design. By using stationary control elements (annular grooves and recesses) directly on the piston rod, the complex valve mechanism with moving components is replaced with a simple, error-resistant geometric feature.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical pneumatic valve system with a geometric control element system. The position sensing is achieved through the interaction of air pressure with the geometric features (annular grooves and recesses) on the piston rod, eliminating mechanical moving parts and reducing complexity.

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

3Measurement precision

If pneumatic valves are installed, then position detection capability is provided, but additional space is required

Engineering Contradiction:
Improveposition detection capabilityVSAvoidspace requirement
Core Design Contradiction:
Measurement precisionVSVolume of stationary object

Solution Approach 1:

The control elements for position detection are nested directly onto the surface of the piston rod, utilizing the existing structural space. The annular grooves and recesses are integrated into the piston rod's geometry, eliminating the need for separate sensing components and additional installation space.

Inventive Principle:
Principle #7Nested doll (Nesting)

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 simplifies the position query process, reduces the risk of errors, and does not require additional space, allowing for precise position detection with a low-complexity, moving-part-free design.

Implementation Method 1

a pneumatic position sensor has an air supply duct (9, 13) for supplying compressed air and an exhaust duct (11) for discharging the compressed air. Furthermore, the pneumatic position sensor comprises a first control element (15, 16), which, depending on the position of the piston rod (2), opens or closes a flow connection from the first air supply duct (9, 13) to the exhaust duct (11)

Methodology Applied
Scientific EffectPneumatic pressure sensing: Pressure Gradient

Data Source

PatentEP4296001B1Clamping device
Publication Date: 2024.09.11 LUGWIG EHRHARDT GMBH
  • EP4296001B1 patent drawingFigure 1
  • EP4296001B1 patent drawingFigure 2
  • EP4296001B1 patent drawingFigure 3

AI summary

The invention relates to a clamping device (1) for clamping a workpiece or a tool (e.g., as a swivel clamp), comprising a guide cylinder with a piston rod running surface (5), a piston rod (2) which is movably guided in the guide cylinder, and a pneumatic position sensor (9-17, M1, M2) for monitoring the position of the piston rod (2). The pneumatic position sensor (9-17, M1, M2) includes an air supply channel (9), an exhaust air channel (11), and a control element (15) which, depending on the position of the piston rod (2), opens or closes a flow connection from the air supply channel (9) to the exhaust air channel (11).The invention provides that the supply air channel (9) opens into a terminal opening (10) in the piston rod running surface (5) of the guide cylinder, while the exhaust air channel (11) opens into a terminal opening (12) in the piston rod running surface (5) of the guide cylinder, wherein the control element (15) is arranged in the outer surface of the piston rod (2) or as a sleeve on the piston rod and, depending on the position of the piston rod (2), opens or closes the flow connection between the terminal opening (10) of the supply air channel (9) and the terminal opening (12) of the exhaust air channel (11) in the piston rod running surface (5) of the guide cylinder.