Engine Starting Air Bleed for Crankcase Unburned Gas Dilution

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Solution Overview

Problem

Fuel gas in a combustion chamber can leak to the crank chamber in the crankcase, increasing the risk of ignition of unburned gas, which is undesirable due to the complexity it adds to the engine system configuration.

Innovation Solution

An engine system with an air supply system that includes an air extraction line to guide compressed air to the crank chamber, reducing the concentration of unburned gas by mixing it with compressed air and purging it through a discharge line, thereby simplifying the system configuration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If measures are implemented to reduce the risk of ignition of unburned gas in the crank chamber, then safety is improved, but device complexity increases

Engineering Contradiction:
ImprovesafetyVSAvoidconfiguration complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The air supply system serves dual purposes: providing starting air to the cylinder for engine startup and simultaneously supplying compressed air to the crank chamber for gas concentration control. This self-service approach eliminates the need for a separate air supply system dedicated solely to crank chamber management, thereby improving safety without increasing overall device complexity.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The air supply system is designed with multi-functionality, where the same system and compressed air source are used for both starting the engine and controlling unburned gas concentration in the crank chamber. This universal application of the air supply system resolves the contradiction by achieving safety improvement through an existing multi-functional system rather than adding dedicated safety equipment.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If compressed air is supplied to the crank chamber to reduce unburned gas concentration, then safety is improved, but energy consumption increases

Engineering Contradiction:
ImprovesafetyVSAvoidcompressed air consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The air supply system provides compressed air to both the cylinder for starting and the crank chamber for safety control without requiring an additional dedicated air supply system. The same compressed air source serves multiple functions, reducing overall energy consumption while maintaining safety improvements.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The compressed air supply is utilized universally for dual purposes: engine starting and crank chamber gas concentration control. This multi-functional use of the same air supply reduces total energy consumption compared to having separate systems, as the air compressor operates regardless and the air is put to productive use in multiple areas.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

The system effectively reduces the risk of ignition of unburned gas in the crank chamber by maintaining the gas concentration below the explosive limit, using a simple configuration that does not complicate the engine system.

Implementation Method 1

guiding the compressed air to a crank chamber in the crankcase... reducing the concentration of unburned gas by mixing it with compressed air

Methodology Applied
Scientific EffectGas mixing and dilution: Diffusion

Data Source

PatentEP4726195A1Engine system
Publication Date: 2026.04.15 MITSUBISHI HEAVY IND ENGINE & TURBOCHARGER LTD
  • EP4726195A1 patent drawingFigure 1
  • EP4726195A1 patent drawingFigure 2
  • EP4726195A1 patent drawingFigure 3

AI summary

This engine system is provided with: an engine including a cylinder and a piston housed in the cylinder; an air tank; an air supply system including a starting air line for guiding compressed air stored in the air tank into the cylinder as starting air of the engine; and a fuel gas supply system for supplying fuel gas into the cylinder. The engine further includes a crankshaft located below the piston for driving the piston, and a crankcase housing the crankshaft. The air supply system further includes a bleeding line for bleeding compressed air flowing through the starting air line and guiding the compressed air to the crank chamber in the crankcase.