Outboard Motor Gear Support Structure for Preload Stability
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Solution Overview
Problem
The existing supporting structures for outboard motor gears face challenges in stabilizing the preload of conical roller bearings and preventing looseness while maintaining space efficiency, particularly when dealing with varying loads during forward and rearward movements, which affects the durability and stability of the gear system.
Innovation Solution
A configuration that includes a first and second conical roller bearing, a compressible biasing member, a spacer, and a supporting member, where the biasing member is placed between the inner and outer races of the bearings to maintain separation and the spacer maintains distance, ensuring the bearings are securely locked to the tubular portion of the second driven gear, allowing for axial displacement and preload adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conical roller bearing is used to support the driven gear, then the bearing capacity for large loads is improved, but the preload stability deteriorates due to thrust variation on the propeller shaft
Solution Approach 1:
A thrust bearing is introduced as an intermediary component between the propeller shaft and the driven gear. The thrust bearing specifically receives and absorbs the thrust load from the propeller shaft, preventing it from being transmitted to the conical roller bearing. This allows the conical roller bearing to maintain stable preload conditions while still handling radial loads, effectively separating the functional responsibilities of different bearing components.
2Duration of action of stationary object
If the driven gear is designed to withstand large loads during forward movement, then the durability under load is improved, but the gear displacement and tooth abutment change, reducing service life
Solution Approach 1:
The thrust bearing acts as a mediator that isolates the driven gear from axial thrust forces. By positioning the thrust bearing between the propeller shaft and the driven gear, it absorbs the axial component of the load, allowing the driven gear to primarily handle radial loads through the conical roller bearing. This separation ensures the driven gear maintains its positional stability and proper tooth engagement even under large load conditions.
3Adaptability or versatility
If the shift mechanism is shared between R/R and C/R specifications, then the versatility is improved, but the driven gear experiences varying loads that affect tooth abutment and reduce reliability
Solution Approach 1:
The thrust bearing serves as a universal intermediary component that handles thrust loads regardless of the rotation specification (R/R or C/R). By placing the thrust bearing in the load path between the propeller shaft and driven gear, it consistently absorbs axial forces in both operating modes, ensuring the driven gear maintains stable positioning and reliable tooth engagement across different specification configurations.
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
This configuration stabilizes the preload of the conical roller bearings, prevents looseness, and enhances the durability of the gear system by maintaining appropriate tooth engagement and reducing the impact of load variations, thereby improving the overall performance and longevity of the outboard motor's gear components.
Implementation Method 1
a compressible and deformable biasing member (543). The biasing member (543) is disposed between an inner race (522, 532) and an outer race (521, 531) of the first conical roller bearing (52) and the second conical roller bearing (53)
Data Source
AI summary
A shift mechanism includes a second driven gear, a first conical roller bearing and a second conical roller bearing, a biasing member, a first spacer, and a nut. The second driven gear meshes with a driving gear. The first and second conical roller bearings are disposed on an outer periphery of a tubular portion of the second driven gear in directions opposite from one another. The biasing member biases one of inner or outer races of the first or second conical roller bearings in directions separate from one another. The first spacer maintains a distance between the other ones. The nut holds the first conical roller bearing and the second conical roller bearing to the tubular portion of the second driven gear. One of the inner or outer races of the first and second conical roller bearings are relatively displaceable in an axial direction.