Powertrain Lubrication Heating for Low-Temperature Pump Start
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Solution Overview
Problem
At very low temperatures, the viscosity of lubrication oil in electric vehicles increases, leading to decreased lubricity and difficulty in starting the lube oil pump, which affects the normal operation of the power system.
Innovation Solution
A powertrain system that disconnects the transmission connection between the drive motor and the wheel based on lube oil parameters, uses idling to stir the lube oil and convert kinetic energy into heat to raise temperature, and employs a locked-rotor state for the oil pump motor to generate heat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lube oil pump is started at very low temperatures, then the power system can operate, but the pump cannot be started due to high viscosity and poor fluidity of the lube oil
Solution Approach 1:
The system performs preliminary heating of the lube oil through the oil cooler acting as a heat exchanger before the pump starts. The control unit detects low temperature conditions and activates the heating function in advance, converting the oil cooler into a heat exchanger that pre-heats the lube oil, thereby ensuring the pump can start reliably without direct heating of the pump motor.
Solution Approach 2:
The oil cooler serves as an intermediary device that mediates between the heat source and the lube oil. Instead of directly heating the pump or lube oil with a heater, the system uses the oil cooler as a heat exchanger to indirectly heat the lube oil, providing a controlled and efficient thermal transfer path that improves heating effectiveness while protecting sensitive components.
2Temperature
If the drive motor is disconnected from the wheel to heat the lube oil through idling, then the lube oil temperature rises rapidly, but energy consumption increases
Solution Approach 1:
The system applies partial action by controlling the drive motor to rotate at a specific speed range (1000-3000 rpm) rather than full speed, and limiting the idling duration to when temperature conditions are met. This partial rotation provides sufficient kinetic energy to heat the lube oil through the transmission structure while avoiding excessive energy consumption that would occur at full motor speed.
Solution Approach 2:
The control unit continuously monitors the lube oil temperature and automatically controls the connection state between the drive motor and wheel based on temperature feedback. When the temperature meets the preset conditions, the system establishes the idling connection to heat the oil; when the temperature rises sufficiently, the system automatically disconnects, creating a closed-loop control that optimizes energy consumption while ensuring adequate heating.
3Force
If the drive motor is connected to the wheel during idling, then torque is transmitted to the wheel, but the lube oil is not effectively heated
Solution Approach 1:
The system dynamically adjusts the connection state between the drive motor and wheel based on real-time temperature conditions. The control unit detects whether the lube oil temperature meets the preset conditions and automatically switches the transmission connection accordingly. This dynamic control ensures that the motor is connected only when heating is needed and disconnected when temperature is sufficient, preventing unnecessary torque transmission while ensuring effective heating when required.
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
Improves lubricity and facilitates smooth starting of the lube oil pump at low temperatures by rapidly heating the lube oil, reducing energy consumption and preventing torque transmission to the wheel.
Implementation Method 1
In the process of idling of the drive motor, the lube oil in the transmission structure of the drive motor is rapidly stirred. In the process in which the lube oil is stirred, kinetic energy is converted into intrinsic energy, and the temperature rises rapidly.
Implementation Method 2
A locked-rotor state for the oil pump motor to generate heat
Data Source
AI summary
A powertrain, a control apparatus, and a motor control unit. The powertrain includes a drive motor and a transmission device. The transmission device disconnects a transmission connection between the drive motor and a wheel based on a result of a comparison between a temperature or a viscosity of a lube oil and a preset parameter value, and a rotational speed of the drive motor varies with the result of the comparison between the temperature or the viscosity of the lube oil and the preset parameter value. The drive motor stirs the lube oil through idling, to make the temperature of the lube oil rise rapidly. The powertrain, the control apparatus and the motor control unit provided can improve fluidity of the lube oil at very low temperatures, so that a lube oil pump can be started smoothly.