Gearbox Coolant Bypass Control for Stable Oil Temperature

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Solution Overview

Problem

Conventional lubricant oil systems for turbine systems struggle to maintain optimal coolant temperature in gearboxes, leading to inefficiencies and mechanical wear due to excessive heat or cold, which affects gearbox lifespan and performance.

Innovation Solution

A coolant temperature control system using bypass lines and a controller to regulate coolant temperature by bypassing the heat exchanger, allowing heated coolant to be recirculated to the gearbox inlet, optimizing efficiency and reducing wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a heat exchanger is used to regulate coolant temperature, then the gearbox temperature can be controlled, but the system complexity increases and response time is delayed

Engineering Contradiction:
Improvecoolant temperatureVSAvoidsystem complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The coolant flow path is segmented into two separate lines: a first coolant supply line that bypasses the heat exchanger and a second coolant supply line that passes through the heat exchanger. This segmentation allows independent control of coolant temperature by selecting which line to use, avoiding the need for complex temperature regulation mechanisms while maintaining temperature control capability

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system dynamically switches between the first and second coolant supply lines based on real-time gearbox temperature conditions. The controller selects the appropriate coolant path (bypassing or passing through the heat exchanger) to actively regulate temperature, providing adaptive temperature control without requiring the heat exchanger to be always in the flow path

Inventive Principle:
Principle #15Dynamics

2Temperature

If coolant flows through the heat exchanger continuously, then temperature regulation is maintained, but energy efficiency decreases due to unnecessary heat exchange

Engineering Contradiction:
Improvecoolant temperature regulationVSAvoidenergy efficiency
Core Design Contradiction:
TemperatureVSLoss of energy

Solution Approach 1:

The system dynamically adjusts coolant flow routing based on gearbox temperature conditions. When the gearbox is within the optimal temperature range, the controller directs coolant through the bypass line, eliminating unnecessary heat exchange and energy loss. When temperature exceeds the threshold, the system switches to route coolant through the heat exchanger for active cooling, thus optimizing energy efficiency while maintaining temperature regulation capability

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The heat exchanger is extracted from the mandatory coolant flow path and placed in an optional bypass configuration. This allows the system to remove the heat exchange function from the continuous operation, engaging it only when temperature regulation is actually needed, thereby eliminating unnecessary energy consumption during normal operating conditions

Inventive Principle:
Principle #2Taking out (Extraction)

3Productivity

If coolant temperature is not optimized, then the system structure remains simple, but gearbox efficiency decreases and mechanical wear increases

Engineering Contradiction:
Improvegearbox efficiencyVSAvoidtemperature control system complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The coolant supply system is segmented into a bypass line and a heat exchanger line, allowing the controller to select the appropriate path based on gearbox temperature. This simple segmentation enables optimal temperature control to maintain gearbox efficiency without requiring complex temperature regulation mechanisms

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The controller monitors gearbox temperature conditions and provides feedback to adjust coolant flow routing accordingly. When the gearbox temperature exceeds the optimal range, the system activates the heat exchanger path; when temperature is within range, it uses the bypass path. This feedback mechanism ensures optimal gearbox efficiency is maintained through simple on/off control rather than complex continuous regulation

Inventive Principle:
Principle #23Feedback

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 maintains optimal coolant temperature, enhancing gearbox efficiency and reducing mechanical wear by preventing scuffing and viscosity-related issues, thus improving overall gearbox performance.

Implementation Method 1

bypass line in fluid communication with the coolant supply lines such that the bypass line provides a pathway for heated coolant to flow from the second coolant supply line to the first coolant supply line

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

conventional lubricant oil systems may include a heat exchanger, which may regulate the temperature of the lubricant oil depending on the operational characteristic of the turbine system

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Data Source

PatentEP4682364A1Gearbox thermal control system
Publication Date: 2026.01.21 GENERAL ELECTRIC CO
  • EP4682364A1 patent drawingFigure 1
  • EP4682364A1 patent drawingFigure 2
  • EP4682364A1 patent drawingFigure 3

AI summary

A system for a gas turbine engine (100) includes a gearbox (155) including a coolant inlet (206), a coolant outlet (208), and a metal portion (210), a first coolant supply line (216) in fluid communication with the coolant inlet (206) of the gearbox (155), a first temperature sensor (228) in thermal communication with the first coolant supply line (216), a second coolant supply line (218) in fluid communication with the coolant outlet (208) of the gearbox (155), a second temperature sensor (230) in thermal communication with the second coolant supply line (218), a third temperature sensor (232) in thermal communication with the metal portion (210) of the gearbox (155), a bypass line connecting the first coolant supply line (216) to the second coolant supply line (218), a bypass valve (222) disposed at a junction of the second coolant supply line (218) and the bypass line, and a controller (234) configured to actuate the bypass valve (222, 226) based on at least one of first temperature data from the first temperature sensor (228), second temperature data from the second temperature sensor (230), or third temperature data from the third temperature sensor (232).