Gear Oil Scraper With Non-Contact Interference Surface
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Solution Overview
Problem
In gas turbine engines, oil adherence to rotating gears due to windage and churning reduces efficiency by increasing rotating mass and creating drag, and existing solutions like shrouds further decrease efficiency.
Innovation Solution
A non-contacting radially inward interference surface, possibly made from sheet metal and integrated with a shroud, is positioned to disrupt air flow and pressure differentials, complementing the shape of the gear teeth to remove entrained oil without physical contact, and cutouts in the sidewall of the shroud facilitate this process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shroud is used to contain oil, then oil management is improved, but efficiency decreases due to increased drag and rotating mass
Solution Approach 1:
The shroud is segmented with cutouts that allow controlled oil egress while maintaining containment benefits. This segmentation enables the system to retain oil management advantages while reducing the harmful effects of full enclosure, thereby improving efficiency without sacrificing oil control.
Solution Approach 2:
The interference surface is positioned at specific locations where oil entrainment occurs most problematically. By applying the oil removal function locally at these critical zones rather than uniformly across the entire shroud, the system achieves effective oil management while minimizing overall drag and energy loss.
2Loss of energy
If oil is removed from rotating gears, then efficiency is improved by reducing drag, but oil management becomes more difficult
Solution Approach 1:
The interference surface acts as an intermediary between the oil-laden gear and the external environment. It provides a controlled interface that removes excess oil through aerodynamic interference while allowing necessary oil to remain on the gear for lubrication, thus simultaneously improving efficiency and maintaining oil management.
Solution Approach 2:
The patent replaces traditional mechanical oil removal methods (such as contact scrapers or wipers) with an aerodynamic interference mechanism. The interference surface utilizes air flow patterns and pressure differentials to remove oil without mechanical contact, reducing drag while maintaining effective oil control.
3Loss of energy
If a non-contacting interference surface is used to remove oil, then efficiency is improved by minimizing contact drag, but device complexity increases
Solution Approach 1:
The interference surface is merged with the shroud structure, forming an integrated component rather than a separate assembly. This consolidation reduces the number of parts and simplifies manufacturing while maintaining the aerodynamic oil removal function, thereby improving efficiency without proportionally increasing device complexity.
Solution Approach 2:
The shroud structure serves multiple functions: it contains oil, provides structural support, and incorporates the interference surface for oil removal. By making the shroud multi-functional, the patent avoids adding separate components for each function, thus improving efficiency while minimizing increases in device complexity.
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 solution effectively reduces oil entrainment around the gear teeth, enhancing the efficiency of the gear assembly by minimizing drag and rotating mass, while maintaining the efficiency of shrouded gear systems.
Implementation Method 1
the radially inward extending interference surface disrupts air flow and pressure differentials
Implementation Method 2
the radially inward extending interference surface disrupts air flow and pressure differentials
Implementation Method 3
oil may become entrained in the windage cloud surrounding the high speed rotating gear. Oil particles are drawn into and entrained about the gear as a result of the high rotary speed, rather than being expelled out of the windage in response to the centrifugal force.
Data Source
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AI summary
A gear assembly (200) is provided. The gear assembly (200) includes a first gear (204) that rotates about a first axis (206) and includes a first gear face (208) with a plurality of first gear teeth (210-212); a second gear (214) that rotates about a second axis (216) and includes a second gear face with a plurality of second gear teeth (218-220), where the first axis (206) is not parallel with the second axis (216) and the first and second teeth (210-212,218-220) rotatably engage as the first gear (204) rotates about the first axis (206) and the second gear (214) rotates about the second axis (216); a scraper (202) that includes a distal interference surface (220) in face-to-face proximity with at least one of the first plurality of teeth (210-212) as the first gear (204) rotates about the first axis (206), where the interference surface (220) removes oil entrained adjacent to the plurality of first or second gear teeth (210-212,218-220) as the first or second gears (204,214) rotate.