Steerable Stern Drive Gearcase With Full Out-of-Water Trim
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Solution Overview
Problem
Existing stern drives face challenges in efficiently steering and trimming mechanisms, particularly in marine vessels, which can lead to inefficiencies and potential damage from water exposure during non-use.
Innovation Solution
A stern drive system with a steerable gearcase and universal joint that utilizes an electric motor for steering and a hydraulic actuator for trimming, integrated with a controller for coordinated operation, allowing for precise steering and full elevation out of water, along with a cooling system and sound enclosure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the gearcase is made steerable to improve maneuverability, then steering control is enhanced, but the device complexity increases
Solution Approach 1:
The patent replaces traditional mechanical steering linkages with an electric motor (actuator) that directly rotates the gearcase about a vertical steering axis. This substitution of mechanical systems with electromechanical actuation simplifies the overall steering mechanism while maintaining precise control capability.
Solution Approach 2:
The electric motor serving as the steering actuator also functions as part of the trimming system, allowing the same component to perform multiple functions (steering and trimming). This multi-functionality reduces the total number of components needed in the system.
2Reliability
If the drive assembly is elevated out of water during non-use to reduce water exposure, then component protection is improved, but the device complexity increases
Solution Approach 1:
The patent replaces traditional hydraulic trimming mechanisms with an electric motor that directly elevates and positions the drive assembly. This electromechanical approach eliminates complex hydraulic lines, pumps, and valves while achieving the same trimming function of raising the drive out of water for protection.
Solution Approach 2:
The same electric motor used for steering also performs the trimming function by elevating the drive assembly vertically. This dual-use of the actuator for both steering and trimming operations reduces system complexity by eliminating the need for separate trimming mechanisms.
3Stability of the object's composition
If a worm gear and ring gear are used to resist rotation of the ring gear, then steering stability is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent utilizes the self-locking characteristic of worm gear mechanics where the worm gear's thread geometry creates high friction that prevents back-driving of the ring gear. This passive mechanical locking provides inherent steering stability without requiring additional active control systems or high-precision manufacturing tolerances.
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
Enhances steering control and protection of drive components by ensuring the drive assembly is fully elevated out of water during non-use, reducing exposure to water and enhancing operational efficiency and durability.
Implementation Method 1
an output shaft of the electric motor configured to rotate in a first direction to cause movement of the rack in a first direction relative to the kingpin and configured to rotate in a second, opposite direction to cause movement of the rack in a second, opposite direction
Implementation Method 2
The output shaft may be coupled to the rack by a ball screw or a roller screw
Implementation Method 3
A hydraulic pump may be configured to supply hydraulic fluid to the cylinder which moves the rack back and forth in the cylinder
Implementation Method 4
The worm gear may be engaged with the ring gear via teeth having a lead angle which causes the worm gear to resist rotation of the ring gear when the gearcase is subjected to an external force
Data Source
AI summary
A stern drive for a marine vessel, the stern drive having a powerhead, a drive assembly configured to support a propulsor for generating a thrust force in water, the propulsor being powered by the powerhead. The drive assembly comprises a driveshaft housing and a gearcase suspended from the driveshaft housing, the gearcase being steerable relative to the driveshaft housing, and a steering actuator configured to steer the gearcase relative to the driveshaft housing.