Electric Vehicle Oil Temperature Control via Pump and Heat Exchanger
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Solution Overview
Problem
The viscosity of oil coolants in electric vehicle powertrains significantly varies with temperature, leading to a substantial decrease in heat dissipation performance due to large-scale temperature fluctuations, necessitating effective oil temperature control to maintain optimal operation.
Innovation Solution
A controller-based method that adjusts the oil temperature by bypassing or enabling the oil-water heat exchanger, modifying water flow rates, and adjusting the power of the oil pump based on detected temperatures to maintain the oil temperature within a target range, utilizing sensors and specified parameters like current, rotation speed, and water temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the oil cooling circuit is used to dissipate heat from the motor and inverter, then the heat dissipation function is improved, but the oil temperature fluctuates greatly causing viscosity changes that worsen heat exchange capability
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the water flow rate through the water pump and the power output of the oil pump based on detected oil temperature. When oil temperature is low, the system increases water flow rate and oil pump power to raise oil temperature. When oil temperature is high, the system decreases water flow rate and oil pump power to lower oil temperature. This dynamic parameter adjustment maintains oil temperature within the optimal range (40-80°C), ensuring stable viscosity and reliable heat exchange capability throughout the cooling process.
2Reliability
If the oil temperature is controlled within a target range, then the heat dissipation performance is maintained, but the control system complexity increases
Solution Approach 1:
The patent implements feedback control by using a temperature sensor to continuously detect the oil temperature in the oil cooling circuit and feeding this information back to the controller. The controller compares the detected temperature with the target temperature range (40-80°C) and automatically adjusts the water pump's flow rate and oil pump's power output accordingly. This closed-loop feedback mechanism maintains reliable heat dissipation performance while keeping the control system relatively simple through automated temperature-regulated adjustments.
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 method effectively stabilizes oil temperature within a target range, enhancing heat dissipation performance and maintaining efficient operation of the powertrain across varying conditions.
Implementation Method 1
transfers heat of the oil cooling circuit to a water cooling circuit by using an oil-water heat exchanger
Implementation Method 2
The water flow rate may be adjusted by adjusting a valve in a water circuit, or may be adjusted by changing a rotation speed of a water pump
Implementation Method 3
increasing a power of an oil pump; reducing a power of an oil pump
Data Source
AI summary
An oil temperature control method is applied to a controller of an electric vehicle that includes an oil cooling circuit, where the oil cooling circuit flows through a motor and an inverter. The method includes the following steps: determining an oil temperature at a detection point, where the detection point is a specified location in the oil cooling circuit; when the oil temperature is lower than a first target temperature, triggering one or more of the following operations: bypassing an oil-water heat exchanger, reducing a water flow rate, and increasing a power of an oil pump; or when the oil temperature is higher than a second target temperature, triggering one or more of the following operations: disabling a bypass path of an oil-water heat exchanger, increasing a water flow rate, and reducing a power of an oil pump.