Piston Assembly Cap Insertion Sealing

Solution Overview

Problem

Existing piston assemblies for hydraulic devices require additional seals on the cylinder wall, which complicates and costs more to produce.

Innovation Solution

A piston assembly design where the cap assembly includes an insertion portion received in the cylinder, allowing seals to be mounted on the insertion portion instead of the cylinder wall, eliminating the need for machined grooves or indentations on the cylinder wall.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If seals are mounted on the cylinder wall, then sealing effectiveness is achieved, but manufacturing complexity and cost increase due to required grooves or indentations

Engineering Contradiction:

Improvesealing effectivenessVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The sealing function is extracted from the cylinder wall and transferred to the cap assembly. The cap assembly includes an insertion portion with sealing surfaces that directly contact the piston, eliminating the need for seals mounted on the cylinder wall. This reduces manufacturing complexity while maintaining sealing effectiveness.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of mounting seals on the cylinder wall to seal against the piston, the invention inverts the approach by providing sealing surfaces on the cap assembly's insertion portion that seal against the piston. This reverses the traditional sealing arrangement and eliminates the need for cylinder wall grooves.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If additional seals and machined portions are added to the cylinder wall, then sealing is improved, but production cost increases

Engineering Contradiction:

Improvesealing effectivenessVSAvoidproduction cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The sealing function is extracted from the cylinder wall and transferred to the cap assembly. The cap assembly includes an insertion portion with sealing surfaces that directly contact the piston, eliminating the need for seals mounted on the cylinder wall. This reduces manufacturing complexity while maintaining sealing effectiveness.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The sealing function is merged into the cap assembly structure itself. The insertion portion of the cap assembly includes integrated sealing surfaces that directly seal against the piston, combining the sealing function with the cap assembly rather than requiring separate seal components.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If seals are mounted on the cylinder wall, then sealing is achieved, but the number of components and assembly steps increases

Engineering Contradiction:

Improvesealing effectivenessVSAvoidnumber of components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The sealing function is merged into the cap assembly structure itself. The insertion portion of the cap assembly includes integrated sealing surfaces that directly seal against the piston, combining the sealing function with the cap assembly rather than requiring separate seal components.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The sealing function is extracted from the cylinder wall and transferred to the cap assembly. The cap assembly includes an insertion portion with sealing surfaces that directly contact the piston, eliminating the need for seals mounted on the cylinder wall. This reduces manufacturing complexity while maintaining sealing effectiveness.

Inventive Principle:

Principle #2Taking out (Extraction)

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 simplifies the production of piston assemblies by eliminating the need for additional seals on the cylinder wall, reducing manufacturing complexity and costs while maintaining sealing effectiveness.

Implementation Method 1

a hydraulic chamber formed axially in between the cap assembly and the piston, wherein a hydraulic pressure in the hydraulic chamber is configured to bias the piston in a first direction along the axis

Methodology Applied

Scientific EffectHydraulic pressure: Pressure Gradient

Data Source

PatentUS12264659B2Piston assembly

Publication Date: 2025.04.01 DPC HYDRAULICS SRL

AI summary

The present disclosure relates to a piston assembly, the piston assembly comprising a cylinder extending along an axis and having an open axial end, a cap assembly closing the cylinder at its open axial end, wherein the cap assembly comprises an insertion portion received in the cylinder at its open axial end, and a piston axially movably disposed within the cylinder and partially received in the insertion portion of the cap assembly. The present disclosure further relates to a variable displacement hydraulic unit including said piston assembly.