Electric Motor Cooling Control for Variable-Pressure Dump Truck Hydraulics
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Solution Overview
Problem
Electric dump trucks face challenges in balancing the miniaturization of electrical devices and stable cooling performance due to varying hydraulic pressure demands, particularly for operations like raising the body, steering, and braking, which require different hydraulic pressures and cooling capacities.
Innovation Solution
A temperature management device that includes a liquid circulation system with a heat exchanger and control unit to maintain the temperature of electrical devices within specific ranges, using cooling water and refrigerant to stabilize the operation of the electric motor and battery by adjusting the temperature through a control device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the capacity of the electric motor for the hydraulic pump is matched to the hydraulic pressure required for raising the body, then the hydraulic pressure for raising the body can be generated, but the size of the electric motor becomes very large and the weight increases
Solution Approach 1:
The patent applies dynamics by making the hydraulic pump's displacement variable rather than fixed. The hydraulic pump includes a variable displacement mechanism that adjusts the amount of hydraulic fluid discharged based on the required operation. For raising the body, the pump provides high displacement to generate high hydraulic pressure. For steering and braking, the pump provides lower displacement. This dynamic adjustment allows a smaller electric motor to deliver variable hydraulic power, resolving the contradiction between achieving high pressure and reducing motor weight.
2Weight of moving object
If the capacity of the electric motor is adjusted to match the hydraulic pressure required for steering and braking, then the electric motor size is reduced, but the hydraulic pressure for raising the body cannot be generated
Solution Approach 1:
The variable displacement hydraulic pump enables the system to overcome the pressure deficiency by dynamically increasing displacement when high pressure is needed. The pump's displacement can be increased during body raising operations to generate sufficient hydraulic pressure, while maintaining smaller motor size for normal operations like steering and braking.
Solution Approach 2:
The patent changes the operational parameters of the hydraulic pump by varying its displacement. The control system adjusts the pump's displacement parameter based on the required hydraulic pressure and flow rate for different operations. This parameter change allows the same pump-motor combination to deliver different levels of hydraulic power, enabling high pressure generation with a smaller motor.
3Area of stationary object
If a smaller capacity electric motor is installed to match steering and braking requirements, then space is saved, but strong cooling performance is required to match the heat generation during body raising
Solution Approach 1:
The variable displacement hydraulic pump reduces the heat generation problem by matching the motor's power output to the actual hydraulic demand. During body raising, the pump operates at high displacement, utilizing the motor's full capacity. During steering and braking, the pump operates at lower displacement, reducing motor load and heat generation. This dynamic power matching allows the use of a smaller motor with less demanding cooling requirements.
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
Enables stable cooling of electrical devices, allowing for miniaturization of the electric motor and increased payload capacity by maintaining temperature within manageable ranges, preventing failures and optimizing space utilization.
Implementation Method 1
a heat exchanger (40) that performs heat exchange with the cooling water by circulating a refrigerant
Implementation Method 2
a temperature sensor (24) that detects the temperature of the cooling water
Data Source
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AI summary
The object of the present invention is to provide a temperature management device that enables stable cooling of an electric motor. The temperature management device of the present invention is a temperature management device 10 for electric working machines, which includes an electric motor 120 having a predetermined first management temperature range, a power supply device 110 that supplies power to the electric motor and has a second management temperature range within the first management temperature range, a hydraulic pump 122 driven by the electric motor to pressurize the hydraulic fluid to a predetermined pressure, and a working device driven at a predetermined pressure by receiving the supply of hydraulic fluid pressurized by the hydraulic pump. Furthermore, the temperature management device includes a pump for pressurizing a heat exchange liquid, a liquid pipe 16 in which a power source, electric motor, and pump are arranged and the liquid circulates, a heat exchanger 90 that exchanges heat with the liquid that has exchanged heat with the power source and electric motor, and a temperature control unit 56 that controls the heat exchanger to maintain the temperature of the liquid within the second management temperature range.