EV Lubricant Warming via Motor Rotation During Charging
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Solution Overview
Problem
In electric vehicles, reduced lubricant temperature increases viscosity, leading to reduced power transmission efficiency and shorter travel distances due to increased rotational resistance in the power transmission path.
Innovation Solution
A controller is used to perform warming control by rotating the electric motor during external charging when the lubricant temperature is low, using heat generated and lubricant stirring to elevate the temperature, ensuring the lubricant is sufficiently warmed before vehicle operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the electric motor is rotated to warm the lubricant during external charging, then the lubricant temperature is increased and power transmission efficiency is improved, but the charging time is extended
Solution Approach 1:
The system performs lubricant warming as a preliminary action during the external charging period, before the vehicle is operated. By utilizing the charging time to warm the lubricant in advance, the system ensures optimal lubricant temperature is achieved before driving, thereby improving power transmission efficiency without extending the actual charging duration required for vehicle operation.
2Productivity
If the lubricant temperature is low, then the viscosity increases and rotational resistance increases, but the power transmission efficiency is reduced and travel distance is shortened
Solution Approach 1:
The control device continuously monitors the lubricant temperature and uses this feedback information to determine when to activate the electric motor for warming. By comparing the measured lubricant temperature against predetermined thresholds, the system activates warming control only when necessary, thereby optimizing power transmission efficiency while avoiding unnecessary energy consumption during charging.
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 increases lubricant temperature, enhancing power transmission efficiency and extending the vehicle's travel distance by maintaining optimal lubricant viscosity.
Implementation Method 1
a first electric motor... configured to be cooled by lubricant of the power transmitting device
Implementation Method 2
the temperature of lubricant for a transmission, gears, etc., provided in a power transmission path between the electric motor and drive wheels is reduced, the viscosity of the lubricant increases
Implementation Method 3
the viscosity of the lubricant increases, resulting in increase of the rotational resistance
Data Source
AI summary
In an electric vehicle, an automatic transmission is provided between a differential unit and drive wheels. The differential unit includes a motor-generator and a power split device, and the motor-generator is cooled by lubricant of the automatic transmission. A battery charger is operable to charge a power storage device using a power supply outside the vehicle. When the temperature of the lubricant is lower than a predetermined temperature upon execution of charging of the power storage device using the charger, and the automatic transmission is in a neutral state, or a power cutting-off state, the controller rotates the motor-generator of the differential unit so as to perform warming control for raising the temperature of the lubricant.