TRU Condenser Fan Shutdown Using Vehicle Motion Airflow

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Solution Overview

Problem

Existing transport refrigeration units (TRUs) in Light Commercial Vehicles (LCVs) consume excessive fuel due to the operation of the condenser fan, which can be reduced by switching it off when the vehicle is in motion and exceeds a predefined speed, utilizing airflow generated by vehicle motion to maintain TRU operation.

Innovation Solution

A method and system that determines vehicle speed and airflow to switch off the condenser fan when the vehicle is moving at or above a predefined speed, using engine parameter values and a controller to manage the condenser fan operation, ensuring sufficient airflow for TRU operation without the fan.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the condenser fan is operated continuously to ensure sufficient airflow for heat rejection, then the TRU can maintain proper cooling performance, but fuel consumption increases

Engineering Contradiction:
Improvecooling performanceVSAvoidfuel consumption
Core Design Contradiction:
TemperatureVSUse of energy by moving object

Solution Approach 1:

The condenser fan operation is made dynamic by switching it off when vehicle speed exceeds a threshold value, allowing the system to adapt to changing airflow conditions. The controller monitors vehicle speed and automatically adjusts fan operation based on whether sufficient natural airflow is available from vehicle motion.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The vehicle's motion itself provides the airflow needed for condenser cooling when speed is sufficient, eliminating the need for the condenser fan to operate. The system utilizes the vehicle's kinetic energy and resulting air flow to serve the cooling function that would otherwise require dedicated fan power.

Inventive Principle:
Principle #25Self-service

2Use of energy by moving object

If the condenser fan is switched off during vehicle motion to reduce fuel consumption, then energy efficiency improves, but cooling performance may deteriorate

Engineering Contradiction:
Improvefuel consumptionVSAvoidcooling performance
Core Design Contradiction:
Use of energy by moving objectVSTemperature

Solution Approach 1:

The controller continuously monitors vehicle speed and uses this feedback to determine when to switch the condenser fan off. When vehicle speed exceeds the threshold, the system detects that sufficient natural airflow is available and automatically disables the fan, maintaining cooling performance while reducing energy consumption.

Inventive Principle:
Principle #23Feedback

3Reliability

If the condenser fan operates at full capacity to ensure adequate heat rejection, then reliable cooling is maintained, but electrical load on the TRU increases

Engineering Contradiction:
Improvecooling reliabilityVSAvoidelectrical load
Core Design Contradiction:
ReliabilityVSPower

Solution Approach 1:

The condenser fan operation is made dynamic by switching it off when vehicle speed exceeds a threshold value, allowing the system to adapt to changing airflow conditions. The controller monitors vehicle speed and automatically adjusts fan operation based on whether sufficient natural airflow is available from vehicle motion.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The vehicle's motion itself provides the airflow needed for condenser cooling when speed is sufficient, eliminating the need for the condenser fan to operate. The system utilizes the vehicle's kinetic energy and resulting air flow to serve the cooling function that would otherwise require dedicated fan power.

Inventive Principle:
Principle #25Self-service

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

Reduces fuel consumption and electrical load on TRUs by selectively switching off the condenser fan during vehicle motion, maintaining TRU performance with minimal operational impact.

Implementation Method 1

a condenser fan configured to move air across the condenser

Methodology Applied
Scientific EffectForced Convection: Forced Convection

Implementation Method 2

The TRUs remove or provide heat to the interior air based on setpoints

Methodology Applied
Scientific EffectHeat transfer: Heat Exchanger

Data Source

PatentEP4289645B1Method for reducing fuel consumption
Publication Date: 2025.08.06 CARRIER CORP
  • EP4289645B1 patent drawingFigure 1
  • EP4289645B1 patent drawingFigure 2
  • EP4289645B1 patent drawingFigure 3

AI summary

A method of operating a condenser of a transport refrigeration unit (TRU) of a vehicle, the method comprising: determining whether revolutions per minute (RPM) of an engine of the vehicle exceeds a predefined level; computing an air flow due to motion of the vehicle from the RPM of the engine if the RPM of the engine exceeds the predefined level; obtaining a nominal air flow due to motion of the vehicle for which the condenser is rated; determining whether the air flow due to motion of the vehicle is equal to or greater than the nominal value; and switching the condenser off if the air flow due to motion of the vehicle is equal to or greater than the nominal value.