Stern Drive Universal Joint Design for Out-of-Water Trimming
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Solution Overview
Problem
Existing marine propulsion systems face challenges in efficiently trimming and steering stern drives out of water, particularly in maintaining non-contact association with the transom while managing vibrations and noise, and require improved methods for installation and vibration isolation.
Innovation Solution
A stern drive system with a trimmable drive assembly featuring a universal joint or dual constant velocity joints, a steerable gearcase housing, and a vibration-dampening mounting assembly, along with a noise-vibration-harshness (NVH) cover, allowing the drive assembly to be raised out of water and installed as a single component, while isolating vibrations and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the drive assembly is made trimmable out of water, then the ability to raise the drive assembly out of water is improved, but the device complexity increases
Solution Approach 1:
The patent applies the dynamics principle by making the drive assembly trimmable through a universal joint that allows the drive assembly to pivot between a horizontal operating position and a vertical trimmed position. This dynamic capability enables the drive assembly to be raised out of water on demand, transforming a static mounting system into a dynamically adjustable one that resolves the contradiction between operational ease and device complexity.
2Ease of operation
If a universal joint is used to couple the powerhead to the driveshaft, then the ability to facilitate trimming is improved, but the device complexity increases
Solution Approach 1:
The universal joint serves multiple functions simultaneously: it couples the powerhead to the driveshaft for power transmission, enables the drive assembly to trim out of water, and accommodates angular misalignments during operation. This multi-functionality resolves the contradiction by achieving trimming capability without requiring separate dedicated mechanisms, thus improving operational ease while minimizing the increase in device complexity.
3Ease of operation
If the gearcase housing is made steerable, then the ability to steer the propulsor is improved, but the device complexity increases
Solution Approach 1:
The steering function is segmented from the main drive assembly by making the gearcase housing independently steerable. This allows the steering mechanism to be positioned and controlled separately from the propulsion system, enabling the propulsor to be steered without affecting the trimmability of the drive assembly. The segmentation resolves the contradiction by distributing functional complexity across separate components.
4Object-affected harmful factors
If a vibration dampening sealing member is used to hold the marine drive in place, then the vibration isolation is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The vibration dampening sealing member acts as an intermediary element between the rigid mounting structure and the drive assembly. This intermediary component absorbs vibrations and mechanical stresses, protecting the transom and mounting hardware from harmful vibrations. The use of this intermediary resolves the contradiction by providing vibration isolation through a compliant material that compensates for manufacturing tolerances, thereby reducing rather than increasing precision requirements.
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 system enables efficient trimming and steering of the stern drive out of water, reduces vibrations and noise, and facilitates easy installation by allowing the drive assembly to be mounted as a single component, enhancing operational efficiency and reducing mechanical stress on the marine vessel.
Implementation Method 1
at least one vibration dampening sealing member which is disposed between the inner and outer clamping plates
Implementation Method 2
a universal joint which couples the powerhead to the driveshaft so that operation of the powerhead causes rotation of the driveshaft
Implementation Method 3
dual constant velocity joints, wherein the dual constant velocity joints are configured to facilitate trimming of the drive assembly
Data Source
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AI summary
A stern drive (12) is for propelling a marine vessel in a body of water. The stern drive (12) comprises a mounting assembly (16) for coupling the stern drive (12) to a transom (18) of the marine vessel. The stern drive (12) further comprises a powerhead (14) configured to operate a propulsor (30) to generate a thrust force in the body of water. The drive assembly (20) is trimmable up and down relative to the mounting assembly (16) and comprises a driveshaft (24) which is operably coupled to the powerhead (14) and the propulsor (30). The stern drive (12) further comprises a universal joint (50) which couples the powerhead (14) to the driveshaft (24) so that operation of the powerhead (14) causes rotation of the driveshaft (24), which in turn operates the propulsor (30). The universal joint (50) is configured to facilitate trimming of the drive assembly (20) an amount sufficient to raise at least a majority of the drive assembly (20) out of the body of water.