Outboard Motor Engine Exhaust System Layout

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Solution Overview

Problem

Outboard motor engines face challenges in compactly arranging catalysts and air pumps due to limited space, leading to size increases and difficulties in achieving efficient exhaust gas purification.

Innovation Solution

The engine design includes an in-line multiple cylinder engine with a vertically oriented crankshaft, a side-mounted intake system, and a strategically arranged exhaust passage with a catalyst and air pump, where the air pump is connected to the crankshaft via a power transmission device and driven by it, allowing for compact placement and efficient secondary air supply to the catalyst.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a catalytic converter and air pump are added to the exhaust system for exhaust gas purification, then exhaust gas purification functionality is improved, but the device complexity and space requirements increase

Engineering Contradiction:

Improveexhaust gas purification functionalityVSAvoidarrangement complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The air pump is integrated into the exhaust system structure, with its housing forming part of the exhaust passage assembly. The power transmission device is merged with the crankshaft structure, eliminating separate mounting requirements and reducing overall device complexity while maintaining exhaust gas purification functionality.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The catalyst is positioned within the exhaust passage in a nested arrangement, where the exhaust passage houses the catalyst housing, which in turn contains the catalyst. The air pump is similarly integrated within the exhaust system structure, creating a compact nested configuration that reduces space requirements while maintaining all necessary functions.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Reliability

If multiple components (engine, intake system, exhaust system, catalyst, air pump) are arranged within the engine housing, then exhaust gas purification is achieved, but the available space is insufficient leading to size increase

Engineering Contradiction:

Improveexhaust gas purificationVSAvoidengine housing volume

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The exhaust passage is configured to extend in multiple dimensions, utilizing vertical and lateral spaces within the engine housing. The catalyst housing and air pump are positioned to optimize three-dimensional space utilization, arranging components along the exhaust flow path rather than requiring additional horizontal space, thereby maintaining compact engine housing volume.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The exhaust system is segmented into functional modules: the exhaust manifold, catalyst housing portion, connection passage, and air pump. This segmentation allows each component to be independently optimized for space efficiency while maintaining overall system functionality, enabling compact arrangement within the engine housing.

Inventive Principle:

Principle #1Segmentation

3Reliability

If the air pump inlet port is positioned higher than the engine inside the cowling to prevent water mixing, then water contamination is prevented, but the arrangement flexibility is reduced

Engineering Contradiction:

Improveprevention of water mixing with secondary airVSAvoidarrangement flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The air pump inlet port is positioned at a specific location within the exhaust system where the local environment ensures water-free air intake. The inlet port is arranged to draw air from a region above the engine housing where water accumulation is minimal, maintaining water contamination prevention while allowing flexible positioning of the air pump within the exhaust system structure.

Inventive Principle:

Principle #3Local quality

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 enables compactification of the outboard motor, reduces the arrangement interval between motors, prevents cavitation, and maintains catalyst activity, thereby improving propulsion force and control stability while ensuring effective exhaust gas purification.

Implementation Method 1

a catalyst provided in the exhaust passage

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 2

an air pump configured to supply secondary air to an upstream side of the catalyst in the exhaust passage... supply oxygen necessary to detoxify the exhaust gas by oxidizing hydrocarbons and carbon monoxides

Methodology Applied

Scientific EffectOxidation: Oxidation

Data Source

PatentUS10059416B2Engine for outboard motor

Publication Date: 2018.08.28 SUZUKI MOTOR CORP

AI summary

An engine for an outboard motor is provided with an engine body, an intake system configured to supply combustion air to the engine body, an exhaust passage formed by connecting the engine body and middle and lower units thereunder, a catalyst provided in the exhaust passage, and an air pump configured to supply secondary air to an upstream side of the catalyst. The intake system is arranged in a side portion of one side of the left or right side of the engine body, and the exhaust passage and the air pump are arranged in a side portion of the other side of the left or right side of the engine body.