Universal Joint Trim Mechanism for Marine Stern Drives
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Solution Overview
Problem
Existing stern drive systems face challenges in efficiently trimming the drive assembly out of the water for maintenance and protection from corrosion, particularly during periods of non-use, as they often require complex hydraulic systems and may not fully elevate the assembly, leading to exposure to water.
Innovation Solution
A stern drive system featuring a universal joint that couples the powerhead to the driveshaft, allowing rotation and trimming of the drive assembly, combined with a steering actuator and controller to position the universal joint neutrally, facilitating the drive assembly's upward movement and full extraction from the water, along with dual constant velocity joints as an alternative configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex hydraulic system is used to trim the drive assembly, then the drive assembly can be positioned out of the water, but the device complexity increases
Solution Approach 1:
The patent extracts the universal joint from the traditional fixed motor mounting and allows it to rotate independently, enabling the drive assembly to be trimmed out of the water without requiring complex hydraulic systems. The universal joint's rotational freedom provides the trimming mechanism, simplifying the overall system while maintaining corrosion protection.
Solution Approach 2:
The patent introduces dynamic positioning capability through the universal joint, which can rotate to accommodate different angles between the motor and driveshaft. This dynamic adjustment allows the drive assembly to be positioned optimally out of the water for corrosion protection and maintenance, replacing static hydraulic trimming systems.
2Reliability
If the drive assembly is fully extracted from the water, then corrosion is prevented, but the universal joint must maintain operational connectivity during rotation
Solution Approach 1:
The universal joint serves multiple functions simultaneously: it transmits rotational power from the motor to the driveshaft while also enabling the drive assembly to trim out of the water. This multi-functionality eliminates the need for separate trimming mechanisms and maintains operational connectivity throughout the trimming range.
Solution Approach 2:
The patent segments the power transmission system by introducing the universal joint as an independent rotational element between the motor and driveshaft. This segmentation allows each component to perform its specific function - the motor generates power, the universal joint transmits and redirects it, and the driveshaft delivers it to the propulsor - while enabling full extraction from the water.
3Ease of operation
If the motor remains fixed relative to the driveshaft, then the structure is simple, but the drive assembly cannot be fully trimmed out of the water
Solution Approach 1:
The patent transforms the fixed motor-driveshaft connection into a dynamic, rotatable connection through the universal joint. This allows the relative position between the motor and driveshaft to change during trimming operations, enabling the drive assembly to be fully extracted from the water while maintaining power transmission capability.
Solution Approach 2:
The universal joint acts as an intermediary element between the motor and driveshaft, mediating the power transmission while accommodating the relative motion required for trimming. This intermediary component enables the motor to remain relatively fixed while the driveshaft can be positioned at various angles, achieving full trimming capability.
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
Enables the stern drive assembly to be fully raised out of the water, preventing corrosion and simplifying maintenance by maintaining operational connectivity during trimming, thus enhancing durability and ease of service.
Implementation Method 1
a universal joint which couples the powerhead to the driveshaft so that operation of the powerhead causes rotation of the driveshaft
Implementation Method 2
dual constant velocity joints as an alternative configuration
Data Source
AI summary
A stern drive is for propelling a marine vessel in a body of water. The stern drive has a powerhead, a mounting assembly configured to affix the powerhead to the transom, inside the marine vessel, and a drive assembly coupled to the mounting assembly, the drive assembly being trimmable up and down relative to the mounting assembly, the drive assembly comprising a driveshaft and an output shaft which extends transversely to the driveshaft. The drive assembly has a driveshaft housing for the driveshaft and a gearcase housing for the output shaft, wherein the gearcase housing is steerable relative to the driveshaft housing. A universal joint couples the powerhead to the driveshaft so that operation of the powerhead causes rotation of the driveshaft, which in turn causes rotation of the output shaft.