Outboard Motor Cam Phaser Arrangement for Compact Width

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Solution Overview

Problem

Conventional cam phaser arrangements in outboard motors and marine engines increase the width of the engine, making it difficult to fit on 26-inch centers, which is a critical design constraint for dual large outboard motors mounted on boats.

Innovation Solution

The cam phaser is disposed on the lower end of the exhaust camshaft, closer to the valley, allowing it to phase the intake camshaft without contributing to the overall width of the outboard motor, and is connected to the intake camshaft via a chain or belt to adjust the timing of rotation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a conventional cam phaser arrangement is used, then camshaft timing adjustment is achieved, but the engine width increases making it difficult to fit on 26-inch centers

Engineering Contradiction:

Improvecamshaft timing adjustmentVSAvoidengine width

Core Design Contradiction:

Adaptability or versatilityVSLength of stationary object

Solution Approach 1:

The cam phaser is repositioned from a location that would increase engine width to a location on the lower end of the exhaust camshaft closer to the valley, utilizing vertical space instead of horizontal space. This dimensional shift allows timing adjustment functionality while maintaining the compact 26-inch center width requirement.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

Instead of placing the cam phaser on the intake camshaft or in a position that would widen the engine, the invention places it on the exhaust camshaft at its lower end. This inverted arrangement achieves the same timing adjustment function while solving the width constraint problem.

Inventive Principle:

Principle #13The other way round (Inversion)

2Length of stationary object

If the cam phaser is positioned to save width space, then the engine fits on 26-inch centers, but the connection mechanism becomes more complex

Engineering Contradiction:

Improveengine widthVSAvoidcam phaser connection mechanism

Core Design Contradiction:

Length of stationary objectVSDevice complexity

Solution Approach 1:

A chain or belt is introduced as an intermediary element to connect the cam phaser on the exhaust camshaft to the intake camshaft. This mediator allows timing adjustment to be transmitted across the engine while maintaining the compact width, simplifying the overall connection mechanism compared to direct mechanical coupling.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9228455B1Outboard motors and marine engines having cam phaser arrangements

Publication Date: 2016.01.05 BRUNSWICK CORP

AI summary

A marine engine for an outboard motor comprises a bank of piston-cylinders, an intake camshaft that operates intake valves for controlling inflow of air to the bank of piston-cylinders, an exhaust camshaft that operates exhaust valves for controlling outflow of exhaust gas from the bank of piston-cylinders, and a cam phaser disposed on one of the intake camshaft and exhaust camshaft. The cam phaser is connected to and adjusts a timing of operation of the other of the intake camshaft and exhaust camshaft with respect to the one of the intake camshaft and exhaust camshaft.