Cantilever Engine Unit Needle Bearing Abrasion
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Solution Overview
Problem
Abrasions and deterioration of metal bearings occur due to a mutual prying motion between the rotational shaft and gear in a cantilever-supported structure, even when they do not relatively rotate, leading to friction and poor lubrication between the bearing's outer and inner rings.
Innovation Solution
The engine unit employs a needle bearing between the rotational shaft and the body of rotation, supported in a cantilever fashion via a second bearing, reducing abrasions and deterioration by minimizing mutual prying motion and ensuring proper lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal bearing is used between the rotational shaft and gear in a cantilever-supported structure, then the rotational shaft can be supported, but abrasions and deterioration of the bearing occur due to mutual prying motion between the rotational shaft and gear
Solution Approach 1:
The patent changes the type of bearing from a conventional metal bearing to a needle bearing, altering the structural parameters of the bearing system. This parameter change allows the bearing to better withstand the mutual prying motion between the rotational shaft and gear, reducing abrasion and deterioration while maintaining support functionality.
2Volume of moving object
If the rotational shaft is supported in a cantilever fashion, then the unit can be downsized, but a mutual prying motion occurs between the rotational shaft and gear causing friction and poor lubrication
Solution Approach 1:
The patent employs a needle bearing with a specific structural configuration that is better suited for cantilever-supported structures. The needle bearing's design parameters allow it to function effectively in the constrained space while mitigating the harmful effects of mutual prying motion, thus maintaining both compactness and lubrication quality.
3Reliability
If a conventional bearing is used with increased lubricating oil, then lubrication is improved, but abrasions and deterioration still occur due to non-coaxial rotation and poor oil film formation
Solution Approach 1:
The patent changes the bearing type to a needle bearing, which has different geometric parameters compared to conventional bearings. This parameter change improves oil film formation even with standard lubricating oil quantities, as the needle bearing's structure allows for better lubrication distribution and film formation, thereby reducing abrasion and deterioration without requiring increased lubricating oil.
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 effectively reduces abrasions and deterioration of the bearings, preventing damage and maintaining the structural integrity of the engine unit while preventing enlargement of the unit's components.
Implementation Method 1
The abrasions and deterioration occur because of a mutual prying motion between the rotational shaft and the gear in a structure where the rotational shaft is supported in a cantilever manner even if the rotational shaft and the gear do not relatively rotate. The non-coaxial rotation causes an area where a good oil film is not formed between the outer ring and the inner ring of the metal bearing. In the area, a friction is generated, so that abrasions and deterioration of the metal bearing occur.
Data Source
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AI summary
A V-belt-type continuously variable transmission (CVT) of an engine unit has a secondary sheave shaft 62, which rotates with a clutch housing 78 of a centrifugal clutch 41. The secondary sheave shaft 62 is supported in a cantilever fashion via bearings 75 and 76. The engine unit has a gear 80, which rotates with a clutch boss 77. Between the secondary sheave shaft 62 and the gear 80, bearings 81 (81a and 81 b) formed with cage-and-roller needle bearings, a type of a needle bearing, are inserted. Such an arrangement can prevent abrasions and deterioration of a bearing inserted between a rotational shaft supported in a cantilever fashion and a body of rotation while avoiding enlargement of the unit.