Pressure-Medium Cylinder With Static End-Position Rod Sealing

Solution Overview

Problem

Pressure-medium cylinders face issues with friction, wear, and cleanability due to dynamic seals, particularly in highly dynamic applications and hygienic design requirements, where contamination and debris entry are not adequately prevented.

Innovation Solution

A pressure-medium cylinder design featuring a static end-position seal with a radially extending stop surface that covers the gap between the piston rod and the cylinder housing, eliminating the need for dynamic seals, reducing friction, and enhancing cleanability by using a return spring for sealing and a sealing body to absorb kinetic energy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a dynamic ring seal is used to seal the piston rod outlet, then sealing is achieved, but friction and wear increase, and cleanability deteriorates

Engineering Contradiction:

ImprovesealingVSAvoidcleanability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The invention removes the dynamic ring seal component from the system. Instead of sealing the piston rod outlet with a dynamic seal that creates dead spaces and cleaning difficulties, the patent extracts this component entirely and replaces it with a static sealing arrangement where the piston rod itself forms the seal at the outlet opening, eliminating the ring gap and associated cleanability issues.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using a separate sealing component (ring seal) to seal the piston rod outlet, the invention inverts the approach by making the piston rod itself the sealing element. The piston rod is designed with a sealing surface that directly contacts the sealing surface at the outlet opening, reversing the traditional sealing architecture.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If a dynamic ring seal is used to seal the piston rod outlet, then sealing is achieved, but friction increases and actuator speed decreases

Engineering Contradiction:

ImprovesealingVSAvoidactuator speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The invention removes the dynamic ring seal component from the system. Instead of sealing the piston rod outlet with a dynamic seal that creates dead spaces and cleaning difficulties, the patent extracts this component entirely and replaces it with a static sealing arrangement where the piston rod itself forms the seal at the outlet opening, eliminating the ring gap and associated cleanability issues.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the mechanical dynamic sealing system (ring seal with contact friction) with a static sealing arrangement. The piston rod is designed with a sealing surface that directly contacts the sealing surface at the outlet opening, eliminating the need for dynamic friction-based sealing and reducing breakaway and frictional forces.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If a dynamic ring seal is used to seal the piston rod outlet, then sealing is achieved, but wear increases and maintenance requirements increase

Engineering Contradiction:

ImprovesealingVSAvoidmaintenance

Core Design Contradiction:

ReliabilityVSEase of repair

Solution Approach 1:

The invention removes the dynamic ring seal component from the system. Instead of sealing the piston rod outlet with a dynamic seal that creates dead spaces and cleaning difficulties, the patent extracts this component entirely and replaces it with a static sealing arrangement where the piston rod itself forms the seal at the outlet opening, eliminating the ring gap and associated cleanability issues.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention eliminates the wear-prone dynamic seal component that requires periodic replacement. By using a static sealing arrangement where the piston rod and outlet opening form the seal, the system removes the consumable sealing element, thereby eliminating maintenance related to seal wear and replacement.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

4Reliability

If a dynamic ring seal is used to seal the piston rod outlet, then sealing is achieved, but friction increases and energy loss increases

Engineering Contradiction:

ImprovesealingVSAvoidfrictional energy loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The invention removes the dynamic ring seal component from the system. Instead of sealing the piston rod outlet with a dynamic seal that creates dead spaces and cleaning difficulties, the patent extracts this component entirely and replaces it with a static sealing arrangement where the piston rod itself forms the seal at the outlet opening, eliminating the ring gap and associated cleanability issues.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the mechanical dynamic sealing system (ring seal with contact friction) with a static sealing arrangement. The piston rod is designed with a sealing surface that directly contacts the sealing surface at the outlet opening, eliminating the need for dynamic friction-based sealing and reducing breakaway and frictional forces.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 reduces friction and wear, improves cleanability, and allows for faster actuator speeds and reduced maintenance by eliminating dynamic seals, while maintaining effective sealing and preventing debris entry, especially in highly dynamic applications.

Implementation Method 1

a return spring arranged in the retraction direction, which seals in the end position in a friction-fit manner

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

The sealing body simultaneously acts as a brake body by absorbing the kinetic energy of the moving parts upon reaching the end position by deformation

Methodology Applied

Scientific EffectDeformation: Deformation

Data Source

PatentUS12188495B2Pressure-medium cylinder having a static end-position seal

Publication Date: 2025.01.07 AVENTICS GMBH

AI summary

A pressure-medium cylinder does not have a component that dynamically seals the piston rod and can be well-cleaned safely from outside. The pressure-medium cylinder includes a cylinder housing, a piston, a piston rod, and a static end-position seal. The piston is axially movably disposed in the cylinder housing. The piston rod is connected to the piston and penetrates the cylinder housing toward an end face through an outlet opening. The piston rod has a stop surface extending radially from the piston rod in a piston rod portion disposed outside of the cylinder housing. The stop surface contacts the cylinder housing in an end position during retracting of the piston rod and thus sealingly covers and/or extends around a gap region or gap regions between the piston rod and an edge of the outlet opening.