Planetary Gear Pin Stepped Bore Lubrication for Fixed Carriers
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Solution Overview
Problem
In planetary gear systems with a fixed planet carrier, splash lubrication methods fail to retain lubricant due to the lack of centripetal force, leading to inefficient lubrication and heat dissipation.
Innovation Solution
A planetary gear pin with an inner bore and an outer bore of different diameters, where the outer bore is narrower, creating a sump that accumulates lubricant and allows it to flow through holes to the inner bore, ensuring consistent lubrication without centripetal force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed planet carrier is used to provide centrifugal pumping action, then the gear structure can be simplified, but lubricant cannot be retained in the bore due to lack of centripetal force
Solution Approach 1:
Instead of relying on centripetal force to retain lubricant (conventional approach), the invention inverts the approach by using a stepped bore configuration where gravity and capillary action cause lubricant to flow from the outer bore to the inner bore, ensuring lubricant delivery without requiring planet carrier rotation
Solution Approach 2:
The bore is segmented into two distinct sections: an outer bore and an inner bore with different diameters. This segmentation creates a stepped configuration that facilitates controlled lubricant flow from the larger outer bore to the smaller inner bore, ensuring reliable lubrication delivery
2Reliability
If splash lubrication is used with a rotating planet carrier, then lubricant can be retained and distributed, but the system cannot operate with a fixed carrier configuration
Solution Approach 1:
The stepped bore configuration enables the pin to self-regulate lubricant flow without requiring external forces from planet carrier rotation. The geometry itself creates the flow path from outer to inner bore, allowing the system to function with either rotating or fixed carriers
3Device complexity
If a single bore configuration is used, then the structure is simpler, but lubricant flow control to the bearing is insufficient
Solution Approach 1:
Instead of using a single bore requiring precise positioning of lubricant delivery features, the invention uses a stepped two-bore configuration where the flow control is inherent in the geometry transition from outer to inner bore, reducing manufacturing 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
This design enhances lubrication and heat dissipation by maintaining a consistent lubricant flow and reducing backflow, improving performance with a fixed or stationary planet carrier.
Implementation Method 1
The difference in diameter between the inner bore and outer bore allows oil flow by gravity from the outer bore to the inner bore
Implementation Method 2
The difference in diameter between the outer bore and inner bore creates a sump where fluid accumulates
Data Source
AI summary
A planetary transmission system is disclosed. In an example, the system may include a planet gear, an outer bearing, and a planetary gear pin including an inner bore fluidly coupled to an outer bore, wherein the outer bore is narrower in diameter than the inner bore and a difference in diameter therebetween allows oil flow by gravity from the inner bore to the outer bore and reduces oil from flow from the inner bore to the outer bore, wherein oil exits the inner bore via a plurality of holes fluidly coupling the inner bore to the outer bearing without valves.