Integrated Tilt-Trim Steering Actuator for Marine Outboard Engines
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Solution Overview
Problem
Existing marine outboard engine tilt-trim subsystems are often bulky and cumbersome, requiring distinct units or complex mechanical structures to manage steering and tilting, which complicates the adjustment of propulsion units in water.
Innovation Solution
An integrated tilt/trim/steering subsystem using dual rotary actuators with oblique spline teeth and matching splines to convert axial movement into rotational movement, allowing for precise steering and tilting with a single unit, including hydraulic actuators connected to a control valve system for hydraulic fluid control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If distinct tilt and trim cylinder units are used, then the tilt-trim requirements can be met, but the system becomes bulky and cumbersome
Solution Approach 1:
The patent combines distinct tilt and trim cylinder units into a single integrated rotary actuator that performs both functions. The actuator includes a piston that can move axially within a cylindrical chamber, with the piston rod connected to a bevel gear mechanism that converts linear piston movement into rotational motion for both tilt and trim operations, thereby reducing system bulk and complexity while maintaining full tilt-trim capability
Solution Approach 2:
The single rotary actuator is designed to perform multiple functions - both tilt and trim operations - through a universal mechanism. The actuator's piston can be positioned at different locations within the cylindrical chamber, and the bevel gear mechanism translates linear piston displacement into rotational motion that controls both the tilt angle and trim angle, making one component serve multiple purposes
2Device complexity
If a single integrated actuator is used, then device complexity is reduced, but controlling different rotation rates for trimming and tilting becomes more difficult
Solution Approach 1:
The patent employs a dynamic control mechanism where the piston's position within the cylindrical chamber determines the output rotation rate. During trimming operations, the piston operates within a first angular range producing a slower rotation rate, while during tilting operations, the piston operates within a second angular range producing a faster rotation rate. This dynamic adjustment of piston position enables variable speed control from a single actuator
Solution Approach 2:
The system changes operational parameters by varying the piston's axial position within the cylindrical chamber. The control system adjusts the hydraulic pressure and piston displacement to achieve different rotation rates - a slower rate for trimming when the piston is in one position range, and a faster rate for tilting when the piston is in another position range, thereby enabling differential speed control through parameter variation
3Adaptability or versatility
If complex mechanical structures are used, then tilt-trim requirements can be met, but the system becomes bulky
Solution Approach 1:
The patent implements a nested structure where the piston is positioned inside the cylindrical chamber, and the bevel gear mechanism is integrated within the actuator body. The piston rod extends through the chamber, and the gear teeth are cut directly into the chamber wall, creating a compact nested arrangement that reduces overall actuator volume while maintaining full tilt-trim functionality
Solution Approach 2:
The invention merges the tilt and trim control mechanisms into a single integrated actuator unit. The piston, cylindrical chamber, and bevel gear mechanism work together as one compact assembly, eliminating the need for separate tilt and trim cylinders and their associated mounting structures, thereby significantly reducing the overall volume of the actuator system
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
The solution provides a compact, efficient system for adjusting the marine outboard engine's position, enabling slower rotation during trimming and rapid elevation, improving operational control and reducing mechanical complexity.
Implementation Method 1
a piston having an inside diameter and an outside diameter, the outside diameter of the piston slidably engaged to the inside wall of the main body and the inside diameter of the piston engaging the shaft, wherein axial movement of the piston is converted into rotational movement
Implementation Method 2
The first and second rotary actuators are hydraulic actuators, each rotary actuator being connected to a control valve system which is connected to a hydraulic pump; wherein axial movement of the piston is effected by hydraulic fluid under pressure pushing on the piston
Data Source
AI summary
A marine outboard engine is disclosed which comprises a drive unit, a tilt/trim/steering subsystem and a stern bracket adapted for connection to an associated watercraft. The tilt/trim/steering subsystem connects the drive unit to the stern bracket and comprises a first rotary actuator carrying the drive unit for pivotal movement about a steering axis that extends generally vertically, and a second rotary actuator connected to the first rotary actuator and supporting the first rotary actuator and the drive unit for pivotal movement about a tilt/trim axis that extends generally horizontally.