Piston Web Recesses for Stroke Piston Compressor Oil Control

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Solution Overview

Problem

Reciprocating piston compressors for vehicles often experience unpleasant oil discharge into the compressed air, leading to contamination and environmental pollution, which is difficult to rectify and shortens the lifespan of systems.

Innovation Solution

The second web of the piston body is set back by a recess relative to its diameter, improving sealing behavior and adjusting pressure between piston rings to reduce oil discharge, with varying recess geometries and asymmetrical designs to enhance tightness and oil drainage options.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional piston design is used, then the compressor structure is simple, but oil discharge into compressed air occurs causing contamination

Engineering Contradiction:
Improveoil discharge into compressed airVSAvoidpiston structure complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent applies local quality by creating recesses at specific locations on the piston webs (between annular grooves) with different geometries. These localized structural modifications alter the flow characteristics and pressure distribution specifically in the ring field area, improving sealing behavior and reducing oil discharge without requiring a complete redesign of the entire piston structure.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent implements asymmetry by designing recesses with different geometries on different webs of the piston body. The recesses are not uniform but vary in shape and position, creating asymmetric flow paths that optimize pressure distribution and sealing performance. This asymmetric design allows for better control of oil-containing air flow behavior while maintaining structural integrity.

Inventive Principle:
Principle #4Asymmetry

2Reliability

If piston rings are added to improve sealing, then oil discharge is reduced, but the device complexity increases

Engineering Contradiction:
Improvesealing behaviorVSAvoidpiston structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by pre-configuring recesses in the piston webs before the piston rings perform their sealing function. These recesses are designed in advance to create optimal pressure distribution and flow conditions that enhance the sealing effectiveness of the piston rings, allowing the rings to work more efficiently in controlling oil discharge.

Inventive Principle:
Principle #10Preliminary action

3Object-affected harmful factors

If recesses are added to adjust pressure distribution, then oil discharge is reduced, but manufacturing complexity increases

Engineering Contradiction:
Improveoil dischargeVSAvoidpiston manufacturing complexity
Core Design Contradiction:
Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by modifying the geometric parameters of the piston web structure through the addition of recesses. These recesses change the physical parameters such as surface area, volume, and flow cross-section in the ring field, thereby altering pressure distribution and flow behavior to reduce oil discharge. The recesses can be designed with various geometries to optimize these parameters for specific application requirements.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2756192B2Stroke piston for a stroke piston compressor for generating compressed air for a vehicle
Publication Date: 2020.11.11 ZF CV SYST HANNOVER GMBH
  • EP2756192B2 patent drawingFigure 1
  • EP2756192B2 patent drawingFigure 2~9c
  • EP2756192B2 patent drawingFigure 4a~6d

AI summary

Stroke piston for a stroke piston compressor for generating compressed air for a vehicle, more particularly a commercial vehicle, consisting of: a piston body with a piston floor (1a), a piston skirt with piston skirt walls (1d) and preferably pin hubs (1c) for receiving a piston pin, and at least two, preferably three piston rings, which can be inserted into circumferential ring grooves (1;2;3) of the piston body. Present between each two ring grooves (1;2;3) and between the piston floor (1 a) and the first ring groove (1) arranged closest to the piston floor (1a) and the ring groove (3) arranged closest to the piston skirt facing away from the other ring groove or grooves are ridges (3a2;3a3) of the piston body. At least one of the ridges (3a2;3a3) of the piston body is recessed at least over a partial section of its ridge height, which is measured parallel to the axis of the piston body, with at least one recess (3b) relative to the diameter of the piston body.