Electric Excavator Cooling Layout With Partitioned Airflow Reuse
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Solution Overview
Problem
In small electric hydraulic excavators, the existing cooling systems are inefficient due to a narrow layout space, leading to excessive cooling system size and difficulty in accommodating the battery unit, and temperature differences between winds from the radiator and oil cooler cause improper air-cooling.
Innovation Solution
The configuration includes an electric motor, a battery unit, a fan, a first heat exchanger for the refrigerant, a second heat exchanger for hydraulic oil, and a partition plate, where the heat exchangers are positioned overlapping the fan and displaced from each other, with the partition plate between them and the battery unit, allowing efficient air-cooling of the electric component and effective temperature partitioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single water cool path is used to cool the battery unit, electric motor, and electric component, then the cooling system is simplified, but the cool system becomes excessively large because the battery unit has low cool temperature requiring oversized cooling capacity
Solution Approach 1:
The patent divides the cooling system into two separate paths: a water cool path for the battery unit and an air cool path for the electric component. This segmentation allows each cooling path to be optimized independently, preventing the need for an oversized cooling system that would be required if a single path had to accommodate both the low-temperature battery cooling and high-temperature electric component cooling requirements.
Solution Approach 2:
The patent applies different cooling methods to different components based on their specific thermal requirements. The battery unit receives water cooling due to its low operating temperature needs, while the electric component receives air cooling suited for its higher temperature operation. This local differentiation of cooling quality optimizes the overall system size.
2Reliability
If two fans are provided for cooling the radiator and oil cooler separately, then each heat exchanger can be cooled effectively, but the space for placing fans becomes large, squeezing space for other components in small electric work machines
Solution Approach 1:
The patent combines the cooling functions of the radiator and oil cooler into a single fan unit. The fan is positioned to simultaneously blow air across both heat exchangers, which are arranged in parallel. This merging of cooling functions reduces the number of fans from two to one, significantly reducing the space required for fan placement while maintaining effective cooling of both components.
Solution Approach 2:
The single fan is designed to perform multiple cooling functions simultaneously - it cools both the radiator and the oil cooler through its airflow. This multi-functional design eliminates the need for separate dedicated fans for each heat exchanger, optimizing the layout space in compact electric work machines.
3Device complexity
If winds from the radiator and oil cooler are mixed for reuse, then the cooling system becomes simpler, but the mixed wind temperature becomes too high for effective air-cooling of the electric component
Solution Approach 1:
The patent segments the wind flow paths into separate channels using partition walls. The wind path from the radiator is kept separate from the wind path from the oil cooler, preventing mixing. This allows the cooler radiator wind to be directed specifically to the electric component for air-cooling without being contaminated by the hotter oil cooler exhaust wind, maintaining effective cooling temperatures.
Solution Approach 2:
The partition walls act as intermediaries that separate and direct different wind flows. By introducing these physical barriers, the system prevents the mixing of winds with different temperatures and directs the appropriate cooler wind from the radiator to the electric component, maintaining the temperature differential needed for effective cooling.
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
This configuration enables a compact layout for the electric work machine, efficiently cooling the electric component and effectively partitioning winds with different temperatures for reuse, optimizing space usage in small excavators.
Implementation Method 1
a fan, wherein the electric component, viewed from above, is positioned between the fan and the battery unit
Implementation Method 2
a first heat exchanger that cools a refrigerant which passes through the battery unit
Implementation Method 3
a second heat exchanger that cools the hydraulic oil
Data Source
AI summary
A hydraulic excavator as an electric work machine includes: an electric motor, a battery unit that stores electric power for driving the electric motor, an electric component to which the electric power is supplied from the battery unit, a first heat exchanger that cools a refrigerant which passes through the battery unit, a hydraulic pump that is driven by the electric motor thereby to discharge a hydraulic oil, a second heat exchanger that cools the hydraulic oil, a fan that has a rotary shaft, and a partition plate. The electric component, viewed from above, is positioned between the fan and the battery unit. The first heat exchanger and the second heat exchanger, viewed from a direction of the rotary shaft, are positioned overlapping the fan, and are so positioned as to be displaced from each other in one direction intersecting the rotary shaft. The partition plate, viewed from above, is positioned between the first heat exchanger and second heat exchanger, and the battery unit, and is positioned across the one direction.