Electric Excavator Thermal Layout for Cabin Heating Retention

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Solution Overview

Problem

In compact electric hydraulic excavators, the installation space constraints lead to reduced heating efficiency due to the proximity of the cooling fan and second reserve tank, which causes the cooling air to lower the temperature of the second heat exchange liquid.

Innovation Solution

A partition wall is provided between the cooling fan and the electrical heater, with the first reserve tank located on the same side as the cooling fan and the second reserve tank on the same side as the electrical heater, preventing the cooling air from hitting the second reserve tank.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the cooling fan and second reserve tank are arranged close to each other due to space constraints, then the installation space is efficiently utilized, but the heating efficiency is reduced because cooling air lowers the temperature of the second heat exchange liquid

Engineering Contradiction:
Improveinstallation spaceVSAvoidtemperature of second heat exchange liquid
Core Design Contradiction:
Area of stationary objectVSTemperature

Solution Approach 1:

The interior of the housing is divided into a first space and a second space by a partition wall. The first space contains the cooling fan and first reserve tank for cooling the electric motor, while the second space contains the electrical heater and second reserve tank for heating the second heat exchange liquid. This segmentation prevents the cooling air from the cooling fan from reaching the second reserve tank, thereby maintaining heating efficiency while utilizing compact space arrangement.

Inventive Principle:
Principle #1Segmentation

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 enhances the heating efficiency of the second heat exchange liquid by preventing temperature reduction while maintaining effective cooling of the first heat exchange liquid.

Implementation Method 1

a radiator that cools a first heat exchange liquid warmed by cooling the electric motor

Methodology Applied
Scientific EffectHeat transfer: Convection

Implementation Method 2

a cooling fan that applies cooling air to the radiator

Methodology Applied
Scientific EffectForced convection: Forced Convection

Implementation Method 3

an electrical heater for heating a second heat exchange liquid to be supplied to the heater core

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 4

a heater core for heating

Methodology Applied
Scientific EffectHeat transfer: Convection

Data Source

PatentEP4582636A1Electric construction machine
Publication Date: 2025.07.09 HITACHI CONSTRUCTION MACHINERY TIERRA CO LTD
  • EP4582636A1 patent drawingFigure 1
  • EP4582636A1 patent drawingFigure 2
  • EP4582636A1 patent drawingFigure 3

AI summary

An electric hydraulic excavator (1) is provided with a heater core (34) for heating, an electrical heater (35) for heating a second heat exchange liquid to be supplied to the heater core (34), and a second reserve tank (39) into which the second heat exchange liquid flows and from which the second heat exchange liquid flows out. On top of this, a partition wall (12) is provided to partition between a first cooling fan (28) and the electrical heater (35), and a first reserve tank (29) is located on the same side as the first cooling fan (28) on a basis of the partition wall (12) as a boundary, and a first heat exchange liquid for cooling an electric motor (15) and the like flows into and flows out from the first reserve tank (29) with a change in temperature. On the other hand, the second reserve tank (39) is located at the opposite side to the first cooling fan (28) on a basis of the partition wall (12) as a boundary.