Outboard Motor Steering Device Swivel Bracket Design

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional outboard motors face limitations in generating a large lift force for steering, achieving a large trim angle, and performing well in high-speed turns due to fixed clamp brackets, engine vibration transmission, limited steering and tilt angles, and susceptibility to water ingress and impact damage.

Innovation Solution

A steering device with a swivel bracket that supports the propulsion unit around a steering shaft, where the drive shaft is freely rotatable and housed in a drive shaft housing connected to the propulsion unit, and an actuator biases a connection extended portion to enhance steering capability, allowing larger steering angles and improved operability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If clamp brackets are fixed to the hull in a cantilever manner, then the structure is simple, but the outboard motor cannot generate a large lift force for steering

Engineering Contradiction:

Improvelift forceVSAvoidclamp bracket structure

Core Design Contradiction:

ForceVSDevice complexity

Solution Approach 1:

The clamp bracket is divided into a pair of left and right brackets that can move independently. This segmentation allows each bracket to flex and adjust position, enabling the generation of large lift forces while maintaining structural simplicity. The brackets are no longer rigidly fixed but can segment their movement to accommodate steering forces.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The clamp bracket structure transitions from a static, rigid configuration to a dynamic one where the brackets can move and adjust during operation. This dynamic capability allows the brackets to generate and respond to large lift forces during steering while keeping the overall structure relatively simple through controlled movement rather than complex rigid mechanisms.

Inventive Principle:

Principle #15Dynamics

2Ease of operation

If the drive shaft and steering shaft are matched (coaxial arrangement), then a large steering angle can be achieved, but the structure becomes more complex

Engineering Contradiction:

Improvesteering angleVSAvoidshaft arrangement structure

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The drive shaft and steering shaft are merged into a single coaxial configuration where the steering shaft is positioned at the center of the universal joint of the drive shaft. This merging of functions into a single aligned structure enables large steering angles while actually simplifying the overall mechanism compared to separate, misaligned shaft systems.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The drive shaft's universal joint is designed to serve dual functions: power transmission and steering rotation. By making the steering shaft coaxial with the drive shaft, the universal joint becomes a multi-functional element that handles both propulsion and steering, reducing the need for additional separate mechanisms and simplifying the overall structure.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of manufacture

If the engine is mounted on the steering shaft receiving portion with the mount gum on the outer side, then installation is simplified, but engine vibration is easily transmitted to the hull

Engineering Contradiction:

Improveengine mountingVSAvoidengine vibration

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

A rubber cushion (mount gum) is introduced as an intermediary element between the engine and the steering shaft receiving portion. This intermediary component serves as a vibration isolator that absorbs and dampens engine vibrations while still allowing for simplified engine mounting. The rubber cushion mediates between the rigid mounting structure and the vibrating engine, preventing vibration transmission to the hull.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Strength

If the span of the steering shaft receiver is short, then the structure is compact, but the outboard motor cannot withstand large propulsion force

Engineering Contradiction:

Improvepropulsion force capacityVSAvoidsteering shaft receiver span

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The steering shaft receiver is designed with a nested structure where the steering shaft is positioned within the universal joint of the drive shaft. This nesting arrangement allows the receiver to maintain a compact external span while internally accommodating the necessary structural elements to withstand large propulsion forces. The nested configuration maximizes strength within a compact footprint.

Inventive Principle:

Principle #7Nested doll (Nesting)

Data Source

PatentUS9233743B2Steering device of outboard motor

Publication Date: 2016.01.12 SUZUKI MOTOR CORP

AI summary

An engine is housed in an engine case and a propulsion unit driven by the engine is provided outside the engine case. By a swivel bracket installed in a predetermined part of the engine case, the propulsion unit is pivotally supported around a steering shaft, and centers of a drive shaft driving the propulsion unit and of the steering shaft are matched.