Opposed Piston Engine Conical Recesses Fuel Mixing

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Solution Overview

Problem

Opposed piston engines face challenges in achieving effective fuel and air mixing, leading to poor combustion, soot emissions, and inefficient operation due to the difficulty in designing a combustion chamber that aligns with side fuel injection, which also complicates servicing and exposes delicate components to high heat.

Innovation Solution

The design features pistons with conical recesses on their faces, allowing for angled fuel injection that avoids plume impingement and enables both fuel injectors to be placed on the same side of the engine, simplifying servicing and isolating components from heat sources.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If fuel injection is performed from the side of the cylinder in opposed piston engines, then the combustion chamber can be formed between the two pistons, but effective mixing of fuel and air becomes difficult resulting in poor combustion and high soot emissions

Engineering Contradiction:
Improvecombustion efficiencyVSAvoidcombustion chamber design
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent employs conical recesses in the piston faces instead of flat surfaces. These conical geometries create curved surfaces that naturally guide and mix the fuel spray with air, improving combustion efficiency while maintaining compatibility with side injection. The curvature of the conical surfaces enhances turbulence and mixing compared to traditional flat piston tops.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent modifies the geometry parameters of the piston face by introducing conical recesses with specific angles and depths. These parameter changes optimize the interaction between the fuel spray and air, creating effective mixing zones that improve combustion while working with the side injection constraint rather than against it.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If injectors are placed on opposite sides of the cylinder to center combustion, then combustion can occur relatively centered in the cylinder, but fuel spray plumes impinge into each other leading to high soot creation

Engineering Contradiction:
Improvecentered combustionVSAvoidsoot emissions
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces asymmetry in the piston face geometry with conical recesses that are specifically shaped and oriented to prevent spray impingement. The conical angles and orientations are designed to guide sprays from opposite injectors in non-interfering paths, allowing centered combustion without the harmful effect of spray collision and soot formation.

Inventive Principle:
Principle #4Asymmetry

3Reliability

If fuel system components are located on both sides of the engine, then fuel injection can be provided from both sides, but service technicians must access both sides to perform service work which is difficult or time consuming

Engineering Contradiction:
Improvefuel injection capabilityVSAvoidservice accessibility
Core Design Contradiction:
ReliabilityVSEase of repair

Solution Approach 1:

The patent merges the fuel injection functionality from both sides into a unified system where both injectors target the same combustion chamber space between the pistons. This allows the fuel system components to be strategically located to improve service accessibility while maintaining the dual-sided injection capability that ensures reliable combustion.

Inventive Principle:
Principle #5Merging (Combining)

4Reliability

If injectors are located on both sides of the engine, then fuel injection from both sides can be achieved, but delicate components are exposed to high heat from exhaust manifolds making them susceptible to leakage and failure

Engineering Contradiction:
Improvefuel injection performanceVSAvoidheat exposure
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the delicate fuel system components from the high-heat zones near the exhaust manifolds by relocating them to cooler areas of the engine. This separation allows the fuel injection system to maintain its performance while being protected from thermal damage that would cause leakage and failure.

Inventive Principle:
Principle #2Taking out (Extraction)

Data Source

PatentEP3201454B1Opposed piston engine with pistons having conical recesses therein
Publication Date: 2020.03.11 VOLVO TRUCK CORP
  • EP3201454B1 patent drawingFigure 1A~1B
  • EP3201454B1 patent drawingFigure 1C~1D
  • EP3201454B1 patent drawingFigure 2A~2B

AI summary

An opposed piston engine includes a cylinder having a cylinder wall, and a pair of opposed pistons, Each face of each piston of the pair of opposed pistons has a top plane and a recess formed therein, each recess comprising a first surface defining part of a cone, the cone defined by the first surface of at least one of the recesses having a longitudinal axis that defines an angle equal to at least one half of a cone angle of the cone with the top plane.