Planetary Gear Oil Discharge Path Reduces Agitation Resistance
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Solution Overview
Problem
In planetary gear systems, lubricating oil passing through rolling element rows experiences agitation resistance, leading to significant power loss due to adhesion and agitation of the oil, which increases friction and reduces efficiency.
Innovation Solution
A planetary gear system design featuring a sun gear with external teeth, a double helical ring gear, and planet gears with annular grooves, along with an oil supply and discharge path that directs lubricating oil to reduce adhesion on rolling elements, and multiple outlets for radial discharge, minimizing oil agitation and friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lubricating oil is supplied to rolling element rows for lubrication, then lubrication effectiveness is improved, but agitation resistance increases causing power loss
Solution Approach 1:
The bearing structure is segmented into multiple rolling element rows (first and second rolling element rows) arranged in parallel. Lubricating oil supply paths are separately provided for each row, allowing independent lubrication control. This segmentation enables effective lubrication of each row while managing oil flow to minimize agitation resistance and power loss.
Solution Approach 2:
A circumferential groove is introduced as an intermediary structure on the outer ring of the bearing. This groove receives lubricating oil from the supply path and distributes it to the rolling element rows. The groove acts as a mediator that controls oil distribution, ensuring adequate lubrication while preventing excessive oil from causing agitation resistance and power loss.
2Stability of the object's composition
If a double helical gear structure is used to compensate axial loads, then bearing stability is improved, but structural complexity increases
Solution Approach 1:
The invention merges the functions of axial load compensation and radial load support into a single double helical gear bearing structure. The bearing combines two helical gear sets with opposite hand orientations, allowing it to handle both axial and radial loads simultaneously. This integration maintains bearing stability while avoiding the need for separate axial and radial bearing components, thus managing structural complexity.
Solution Approach 2:
The double helical gear bearing is designed as a universal component that performs multiple functions: supporting radial loads, compensating axial loads, and providing lubrication pathways. The bearing structure incorporates circumferential grooves and oil supply paths that enable it to function as both a load-bearing element and a lubrication distribution system, reducing the need for additional separate components.
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 design effectively reduces agitation resistance and power loss by efficiently directing lubricating oil, resulting in a 34% reduction in power loss compared to conventional systems.
Implementation Method 1
a large amount of lubricating oil passing through the rolling element rows is adhered to the rolling elements and agitated. As a result, the agitation resistance of the lubricating oil is increased, causing significant power loss.
Data Source
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AI summary
A planetary gear system (1) includes: a sun gear (5) having external teeth; a ring gear (9) having internal teeth; at least one planet gear (7) having external teeth meshed with the external teeth of the sun gear and the internal teeth of the ring gear. The planet gear (7) has, at its outer circumferential face, the external teeth which are formed of a pair of sets of teeth aligned in an axial direction and an annular groove (17) which is formed between the pair of sets of teeth. The planetary gear system (1) further includes: a fixed support shaft (23) provided for each of the at least one planet gear (7) and configured to rotatably support the planet gear (7) via a bearing, the bearing including a pair of rolling element rows (72) aligned in the axial direction; an oil supply path (LP) through which lubricating oil is supplied, at an inner side of the planet gear (7), to the pair of rolling element rows (72); and an oil discharge path (oil outlet 91) which extends through the planet gear (7) and through which the lubricating oil is discharged to the annular groove (17) from space between the pair of rolling element rows (72) which are provided at the inner side of the planet gear (7).