Piston Support Ring Relief-Milled Design for Extrusion Control

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Solution Overview

Problem

Conventional pistons face challenges in achieving a balance between maximizing wear on bearing rings while minimizing piston ring extrusion, often requiring complex designs and multiple parts, which complicates manufacturing and assembly.

Innovation Solution

A piston design featuring a peripheral groove with a support ring relief-milled from the piston body, allowing the piston body to move relative to the support ring, reducing radial play and extrusion risk, and simplifying the structure to few individual parts by integrating the support ring with the piston body.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If the play between the piston and the cylinder is increased to maximize bearing ring wear, then the bearing ring wear is improved, but the piston rings may extrude into the gap between the L-shaped disks and the cylinder

Engineering Contradiction:

Improvebearing ring wearVSAvoidpiston ring extrusion

Core Design Contradiction:

Duration of action of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The piston structure is segmented into L-shaped chamber rings and adjustable piston rings that can move independently. The piston rings are arranged radially inwardly at a distance from the delimiting surface of the chamber rings, allowing them to move axially within the chamber rings to compensate for bearing wear while maintaining sealing contact with the cylinder.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The piston rings are made adjustable with angled surfaces that allow axial movement based on wear conditions. As the bearing ring wears, the piston rings can move axially to maintain optimal contact with the cylinder surface, dynamically adapting to the changing gap conditions without extruding into the gap.

Inventive Principle:

Principle #15Dynamics

2Object-affected harmful factors

If adjustable slotted piston rings with angled surfaces are used to prevent piston running against the cylinder, then the risk of extrusion is reduced, but the manufacturing complexity increases due to the need for leading gas pressure into the annular space

Engineering Contradiction:

Improveextrusion riskVSAvoidmanufacturing complexity

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The complex gas pressure leading system and angled surface adjustments are extracted from the piston ring design. Instead, a simple backup ring is added to the piston ring groove to prevent extrusion, while the gas pressure leading is simplified to a single hole through the piston rod that distributes pressure uniformly to all piston rings without requiring complex annular space connections.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If adjustable piston rings with axial clamping by adjacent chamber rings are used, then the piston is prevented from running against the cylinder, but the manufacturing difficulty increases due to the double fitting problem

Engineering Contradiction:

Improvepiston guidanceVSAvoidassembly difficulty

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The complex adjustable chamber rings with angled surfaces are replaced with simple, inexpensive backup rings that are easily manufactured and assembled. The backup rings provide the necessary support function without requiring precise angular adjustments or complex fitting procedures, significantly simplifying the assembly process while maintaining piston guidance reliability.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

4Duration of action of stationary object

If piston rings are pushed against the cylinder with different pressure forces to compensate for wear, then the wear limit is extended, but undesired differences in wear rates on the piston rings occur

Engineering Contradiction:

Improveservice lifeVSAvoidwear rate uniformity

Core Design Contradiction:

Duration of action of stationary objectVSStability of the object's composition

Solution Approach 1:

A single gas pressure leading hole through the piston rod serves multiple functions: it distributes gas pressure uniformly to all piston rings simultaneously, maintains axial positioning of all piston rings, and compensates for bearing wear across the entire piston assembly. This universal approach ensures all piston rings experience similar pressure conditions and wear rates, preventing differential wear problems.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS9138839B2Piston having position rings and support rings

Publication Date: 2015.09.22 HOERBIGER KOMPRESSORTECHNIK HLDG GMBH

AI summary

A support ring (12) and a piston ring (11) that are arranged in a peripheral groove (20) provided on a piston body (15), the axial width of the peripheral groove (20) being greater than the total axial width of the support ring (12) and of the piston ring (11), and the support ring (12) is arranged radially inwardly at a distance from the piston body (15), and the support ring (12) is relief-milled from the piston body (15) as an unbroken ring.