Aircraft Engine Oil Makeup and Overfill Control
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Solution Overview
Problem
Prior art aircraft engine oil systems require manual refilling on the ground due to varying aircraft attitude and oil temperature, leading to potential overfilling or underfilling issues, which can cause wear to engine shaft seals or low oil pressure.
Innovation Solution
A lubrication system with an engine lubricant tank, an auxiliary lubricant tank, and hydraulic connections including a lubricant makeup pump and a scavenge pump to maintain optimal lubricant levels during flight, allowing for continuous lubrication and preventing overfilling or underfilling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual refilling is performed on the ground, then the engine oil tank can be refilled, but the risk of overfilling or underfilling increases due to varying aircraft attitude and oil temperature
Solution Approach 1:
The system enables automatic self-regulation of oil levels through the interaction of the makeup pump, scavenge pump, and relief valves. The system automatically maintains proper oil levels without requiring manual intervention or ground crew procedures, eliminating the risks associated with manual refilling while the aircraft is in operation.
Solution Approach 2:
The system incorporates automatic feedback control through the makeup pump and scavenge pump that respond to oil level conditions. When oil levels drop, the makeup pump activates to replenish oil; when levels rise above the maximum, the scavenge pump activates to remove excess oil, creating a self-regulating feedback mechanism that maintains optimal oil levels.
2Measurement precision
If the aircraft attitude and oil temperature vary, then the effective oil level varies, but manual measurement procedures become more complex and error-prone
Solution Approach 1:
The system eliminates the need for manual measurement procedures by implementing automatic oil level control. The makeup pump and scavenge pump system self-regulates oil levels based on tank conditions, removing the complexity of ground crew procedures and the need for precise manual measurements under varying flight conditions.
Solution Approach 2:
The patent replaces manual mechanical measurement and refilling procedures with an automated pump-based system. The mechanical intervention of ground crew measuring and pouring oil is substituted with an automated system that uses the makeup pump to add oil and the scavenge pump to remove excess oil, eliminating measurement errors.
3Quantity of substance
If excessive oil is supplied above the maximum level, then the oil tank is fully filled, but accelerated wear to engine shaft seals occurs
Solution Approach 1:
The system prevents excessive oil supply through feedback control. The scavenge pump is activated when oil levels reach the maximum mark, automatically removing excess oil and preventing it from entering the engine. This feedback mechanism ensures oil quantity is maintained within safe limits, preventing shaft seal wear.
Solution Approach 2:
The system takes preliminary action to prevent harmful effects by using the scavenge pump to remove excess oil before it can cause damage to shaft seals. The overfill prevention mechanism activates in advance to counteract the potential harmful effect of excessive oil supply, protecting the engine components from wear.
4Quantity of substance
If insufficient oil is supplied, then the oil tank level is low, but low oil pressure results
Solution Approach 1:
The system prevents insufficient oil supply through feedback control. The makeup pump is activated when oil levels drop, automatically replenishing oil to maintain adequate quantity and pressure. This continuous monitoring and replenishment ensures oil pressure remains within operational limits.
Solution Approach 2:
The system takes preliminary action to prevent low oil pressure by using the makeup pump to replenish oil levels before they drop to critical thresholds. The system proactively maintains adequate oil quantity to prevent the harmful effect of low oil pressure, ensuring continuous proper lubrication.
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 system ensures consistent lubricant levels in the engine lubricant tank, preventing wear and maintaining optimal oil pressure by continuously supplying and removing lubricant as needed, independent of ground refilling procedures.
Implementation Method 1
a lubricant makeup conduit hydraulically connecting the auxiliary lubricant tank to the lubricant makeup port
Implementation Method 2
an overfill conduit hydraulically connecting the overfill port to the auxiliary lubricant tank
Implementation Method 3
a check valve in the lubricant makeup conduit, the check valve oriented to allow lubricant flow through the check valve toward the lubricant makeup port and to prevent lubricant flow from the lubricant makeup port past the check valve
Data Source
AI summary
A lubrication system for an aircraft engine includes an engine lubricant tank including at least a supply port hydraulically connectable to the aircraft engine, a lubricant makeup port, and an overfill port, an auxiliary lubricant tank, a lubricant makeup conduit hydraulically connecting the auxiliary lubricant tank to the lubricant makeup port. The lubricant makeup conduit includes a pump operable to move lubricant from the auxiliary lubricant tank to the lubricant makeup port, and an overfill conduit hydraulically connecting the overfill port to the auxiliary lubricant tank. A method of operating a lubrication system of an aircraft engine of an aircraft is also disclosed.