Electric Excavator Battery Cooling With Switchable Thermal Modes
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Solution Overview
Problem
Electric work machines, such as electric excavators, face challenges in managing the cooling of large lithium-ion batteries due to harsh operating environments and limited cooling from ambient air movement, which is different from conventional vehicles.
Innovation Solution
An integrated thermal management system that includes a battery module with natural convection cooling, a radiator with a coolant loop, and a chiller with a refrigerant loop, along with a controller to switch between passive, semi-passive, and active cooling modes using a fan, coolant pump, and compressor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If natural convection cooling is used for the battery, then the system complexity is reduced, but the cooling effectiveness is insufficient under harsh operating conditions
Solution Approach 1:
The cooling system dynamically transitions between passive natural convection mode and active forced convection mode (using fans and coolant pumps) based on real-time temperature conditions. This allows the system to maintain simplicity during normal operation while providing enhanced cooling capability when needed, resolving the contradiction between system complexity and cooling effectiveness.
Solution Approach 2:
The system utilizes natural convection currents and ambient air flow to provide baseline cooling without requiring external power or control systems. The battery housing design incorporates natural airflow paths that enable self-cooling during low-stress operations, reducing system complexity while maintaining adequate cooling for moderate conditions.
2Reliability
If forced convection cooling with fans and coolant pumps is implemented, then cooling effectiveness is improved, but energy consumption increases
Solution Approach 1:
The cooling system operates dynamically, activating fans and coolant pumps only when temperature thresholds are exceeded. During normal operating conditions, the system relies on passive natural convection, minimizing energy consumption. When high thermal loads are detected, the system transitions to active forced convection to maintain cooling effectiveness, thus balancing energy use with cooling performance.
3Temperature
If active refrigeration with chiller and compressor is used, then battery temperature control is enhanced, but the device complexity and energy consumption increase significantly
Solution Approach 1:
The chiller system uses a coolant as an intermediary substance to transfer heat from the battery to the ambient environment. The coolant circulates through heat exchangers, absorbing heat from the battery and dissipating it externally. This intermediary approach enables precise temperature control without requiring direct contact between the battery and complex refrigeration components, reducing overall system complexity while maintaining effective temperature management.
4Productivity
If integrated thermal management system is implemented, then overall system efficiency is improved, but the device complexity increases
Solution Approach 1:
The thermal management system merges multiple cooling functions (natural convection, forced convection with fans, coolant circulation, and chiller refrigeration) into a single integrated system. The controller coordinates these different cooling mechanisms to work together, selecting and combining appropriate modes based on real-time thermal conditions. This integration improves overall system efficiency by optimizing heat dissipation across all components while managing complexity through unified control.
Solution Approach 2:
The thermal management system is designed with multi-functionality, where a single system architecture can handle various cooling requirements from passive natural convection to active refrigeration. The same basic infrastructure (coolant loops, heat exchangers, control systems) supports multiple operating modes and can adapt to different thermal loads, reducing the need for separate dedicated systems and thereby managing complexity while maintaining high efficiency.
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
Effectively manages battery temperature across varying conditions, ensuring efficient cooling and extending battery lifespan in harsh environments by utilizing natural convection, forced convection, and active refrigeration as needed.
Implementation Method 1
an air passage configured to allow natural convection cooling of the battery by ambient air
Implementation Method 2
the fan is operative to provide forced convection cooling by passing ambient air across the radiator
Implementation Method 3
a chiller including a first flow path and a second flow path in heat exchange relation with each other
Data Source
AI summary
An integrated vehicle and battery thermal management system for an electric work machine may include a battery module, a radiator, a fan to move air across the radiator, a battery coolant loop including a coolant pump, a refrigerant loop including a compressor, and a chiller providing heat transfer from the battery coolant loop to the refrigerant loop. A controller is operably connected to the coolant pump, the compressor and the fan and is configured to provide a passive cooling mode, a semi-passive cooling mode, and an active cooling mode, dependent upon monitored temperatures in the system.