Electric Oil Pump Cold-Start Heating via Stator Coils
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Solution Overview
Problem
Automotive electric oil pumps face challenges in starting up at low temperatures due to high viscosity of oil, which causes viscous friction and impedes rotor rotation, requiring an overpowered motor and risking damage.
Innovation Solution
An automotive electric oil pump with a control module that energizes stator coils during a cold-start phase to heat the oil, reducing viscosity and allowing startup with a smaller motor, using a direct convective heat transfer and a closed oil circuit for efficient heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pump is started at low temperatures with cold oil, then the pump can be started, but the high viscosity of the oil causes viscous friction that impedes rotor rotation and may cause damage
Solution Approach 1:
The control module activates the stator coils before the pump rotor starts rotating to heat the oil in the motor chamber. This preliminary heating action reduces the oil viscosity before the rotor begins to turn, eliminating the harmful viscous friction that would otherwise impede rotation and cause damage during cold-start conditions
Solution Approach 2:
The stator coils, which normally only generate electromagnetic fields to drive the rotor, are instead used to generate heat through resistive heating. This converts the harmful cold oil viscosity into a beneficial heating effect, using the stator coils themselves as heating elements to warm the oil and enable successful pump startup
2Reliability
If an overpowered electric drive motor is used to rotate the pump rotor at low temperatures, then the pump can start, but the motor size and torque requirements increase
Solution Approach 1:
By heating the oil in advance using the stator coils before rotor rotation begins, the oil viscosity is reduced beforehand. This preliminary action means that when the rotor finally starts to rotate, it encounters much lower viscous friction, allowing a smaller motor with lower torque requirements to successfully start the pump during cold conditions
3Temperature
If the stator coils are energized continuously to heat the oil, then the oil temperature is maintained, but energy consumption increases
Solution Approach 1:
The control module energizes the stator coils only during specific periods - namely during cold-start conditions when oil heating is required. Once the pump is running and the oil has been heated to the appropriate temperature, the stator coils are de-energized. This periodic, conditional activation maintains oil temperature when needed while avoiding continuous energy consumption
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 successful startup at low temperatures with reduced motor size and torque requirements, shortening the start-up phase and extending the operating temperature range.
Implementation Method 1
The control module is configured to energize the plurality of stator coils in a cold-start phase if a temperature of the oil within the motor chamber is below a defined temperature value
Implementation Method 2
a partial volume of the oil within the pumping chamber thereby flows through the motor chamber
Data Source
AI summary
An automotive electric oil pump includes a static pump housing, an electric drive motor, a rotatable pump wheel, and a control module. The static pump housing defines a pumping chamber and a motor chamber which are fluidically connected to each other. The electric drive motor is arranged within the motor chamber. The electric drive motor has a motor stator and a motor rotor. The motor stator has stator coils. The rotatable pump wheel pumps oil through the pumping chamber, wherein a partial volume of the oil within the pumping chamber thereby flows through the motor chamber. The control module energizes the stator coils in a cold-start phase if a temperature of the oil within the motor chamber is below a defined temperature value and inhibits a rotation of the motor rotor. The motor stator directly contacts the oil.