Internal Combustion Engine Breather Device Oil Management

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Solution Overview

Problem

Existing breather devices for internal combustion engines face challenges in preventing oil from rising in the breather passage and oil splash from entering the breather chamber, especially when the vehicle corners or accelerates/decelerates, leading to clogging and weakened negative pressure.

Innovation Solution

A breather device design featuring a head cover main body with a downwardly recessed part and a peripheral wall forming a valve actuation chamber, including a first and second communication hole to maintain negative pressure and prevent oil intrusion, with the second communication hole having a smaller cross-sectional area than the first to minimize oil entry, and a bulging part for mechanical stability and oil drainage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the auxiliary opening size is increased to prevent oil flooding and maintain negative pressure, then the negative pressure weakening effect is improved, but oil splash from the valve actuation chamber enters the breather chamber along with gas

Engineering Contradiction:

Improvenegative pressure maintenanceVSAvoidoil intrusion into breather chamber

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by creating a gap (G) in a specific location between the peripheral wall (41B) and the downwardly recessed part (41D) where oil is less likely to reach. This localized gap provides a safe passage for air to enter the breather chamber without exposing the larger opening to oil splash zones. The communication holes (65, 68) are strategically positioned at different locations and sizes to provide localized functions: one for primary air intake and the other as a backup or supplementary path.

Inventive Principle:

Principle #3Local quality

2Reliability

If a single large auxiliary opening is provided to prevent oil flooding, then the negative pressure weakening effect is improved, but the opening area increases allowing oil splash to enter with gas

Engineering Contradiction:

Improvebreather passage protectionVSAvoidauxiliary opening area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent segments the single auxiliary opening into multiple communication holes (65, 68) with different sizes and locations. Instead of providing one large opening that would allow oil intrusion, the system uses multiple smaller openings that collectively provide sufficient air intake while minimizing oil exposure. The gap (G) is also segmented as a distributed passage rather than a single large opening.

Inventive Principle:

Principle #1Segmentation

3Object-affected harmful factors

If the first communication hole is made smaller to prevent oil entry, then oil intrusion is reduced, but the hole may be clogged by oil or submerged when the oil reservoir tilts

Engineering Contradiction:

Improveoil intrusion preventionVSAvoidcommunication hole functionality

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent prepares for potential clogging or submersion of the first communication hole (65) by pre-providing the second communication hole (68) as a backup pathway. When the first hole becomes blocked or submerged due to oil reservoir tilting, the second hole ensures continuous air intake functionality. This preliminary action maintains system reliability without requiring the first hole to be oversized.

Inventive Principle:

Principle #10Preliminary action

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

Effectively prevents oil from rising in the breather passage and entering the breather chamber, maintaining negative pressure and ensuring efficient blow-by gas recirculation without clogging, even when the oil reservoir tilts.

Implementation Method 1

recirculating the blow-by gas produced in a crank chamber to an intake passage by intake negative pressure

Methodology Applied

Scientific EffectNegative pressure: Pressure Gradient

Implementation Method 2

a breather chamber for removing oil mist from the blow-by gas drawn from the crank chamber

Methodology Applied

Scientific EffectGravity separation: Gravitation

Implementation Method 3

the negative pressure in the breather chamber is weakened by the air drawn from the valve actuation chamber into the breather chamber via the auxiliary opening so that the rise of the oil into the breather chamber can be avoided

Methodology Applied

Scientific EffectPressure equalization: Pressure Gradient

Data Source

PatentUS10570790B2Breather device of internal combustion engine

Publication Date: 2020.02.25 HONDA MOTOR CO LTD

AI summary

In a breather device of an internal combustion engine, a breather chamber is defined by a head cover main body and a chamber forming member. The breather device includes an upstream breather passage communicating a first end of the breather chamber with a crank chamber, a downstream breather passage communicating a second end of the breather chamber with an intake passage, an oil return passage formed in a cylinder head to communicate a valve actuation chamber with the crank chamber, a first communication hole formed in a lower part of a recessed part of the breather chamber adjoining the first end of the breather chamber to communicate the breather chamber with the valve actuation chamber, and a second communication hole formed in a part of the breather chamber downstream of the first communication hole to communicate the breather chamber with the valve actuation chamber.