Engine Breather Mechanism Preventing Oil Suction

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Solution Overview

Problem

Existing engines with breather mechanisms allow lubricating oil to enter the air intake system when returned from a laterally laid-down position to a vertically upright position, leading to undesirable suction of oil into the engine's combustion chamber.

Innovation Solution

The breather mechanism is designed with a breather passage that prevents lubricating oil from entering the breather chamber by positioning the outlet end portion above the inlet end portion when the engine is upright, utilizing the higher specific gravity of oil to keep it from being lifted by blow-by gas, ensuring only gas is sucked into the combustion chamber.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the breather passage is positioned horizontally or with the inlet above the outlet, then lubricating oil can be drained from the crankcase during lateral transportation, but lubricating oil enters the breather chamber and air intake system when the engine is returned to vertical position

Engineering Contradiction:

Improvebreather mechanism reliabilityVSAvoidlubricating oil suction into air intake system

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The breather passage is inverted so that the outlet end portion is positioned higher than the inlet end portion when the engine is in vertical position. This inversion prevents lubricating oil from entering the breather chamber by utilizing gravity to keep oil below the inlet opening, while still allowing blow-by gas to escape through the passage.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The breather passage acts as an intermediary structure with specific geometric configuration (outlet higher than inlet) that mediates between the crankcase and breather chamber. This intermediate structure selectively allows gas passage while blocking oil entry by positioning the outlet above the inlet level.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the engine is designed for vertical operation only, then lubricating oil remains in the crankcase during operation, but the engine cannot be stably transported or stored in lateral position

Engineering Contradiction:

Improveengine position adaptabilityVSAvoidlubricating oil entry into breather passage

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The breather passage is designed with multi-functional capability to handle different engine orientations. When the engine is vertical, the outlet-higher-than-inlet configuration prevents oil entry. When the engine is lateral, the passage still allows gas venting while the oil naturally settles away from the inlet due to gravity, enabling stable transportation in various positions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The relative position parameters of the breather passage inlet and outlet are specifically configured so that the outlet end portion is higher than the inlet end portion in vertical position. This parameter configuration creates a gravity-based barrier that prevents oil migration to the breather chamber regardless of engine orientation changes during transport and operation.

Inventive Principle:

Principle #35Parameter changes

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 configuration effectively prevents lubricating oil from being sucked into the air intake system, maintaining engine performance and reducing potential damage from oil ingestion.

Implementation Method 1

utilizing the higher specific gravity of oil to keep it from being lifted by blow-by gas

Methodology Applied

Scientific EffectSpecific gravity difference: Density Gradient

Implementation Method 2

the breather valve being openable to allow the blow-by gas to flow out of the crankcase into the breather chamber via the breather passage once inner pressure of the crankcase exceeds a predetermined value

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Data Source

PatentUS8978631B2Engine equipped with breather mechanism

Publication Date: 2015.03.17 HONDA MOTOR CO LTD

AI summary

Breather mechanism includes a breather passage opening into a crankcase, a breather chamber communicating with the crankcase via the breather passage, and a valve provided in the breather chamber and openable to allow blow-by gas to flow from the crankcase into the breather chamber once inner pressure of the crankcase exceeds a predetermined value. When the engine is placed in a laterally laid-down position, entry, into the breather chamber, of lubricating oil is prevented by the breather passage. When the engine is placed in a vertically upright position, an outlet end portion of the breather passage is located above an inlet end portion of the breather passage.