Hybrid Vehicle Motor-Generator Cooling Layout to Prevent Rotor Submersion
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Solution Overview
Problem
Conventional cooling systems for hybrid vehicles disrupt the rotation of high-frequency operating motors due to stirring resistance when the oil pump is stopped, causing inefficient cooling and rotor submersion issues.
Innovation Solution
A cooling system configuration where the motor is positioned downstream of the pressurizing unit and the generator is positioned downstream of the motor and upstream of the pressurizing unit in the coolant recirculating direction, preventing rotor submersion and maintaining efficient cooling without disturbing motor rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the oil pump is stopped to save energy when motor temperature is low, then energy consumption is reduced, but the rotor becomes submerged in oil causing stirring resistance that disturbs motor rotation
Solution Approach 1:
The patent changes the spatial arrangement from horizontal (coaxial in transverse direction) to vertical (stacked in longitudinal direction), creating a height difference between motor and generator oil reservoirs. This dimensional change allows gravity to prevent oil backflow into the motor when the pump stops, eliminating stirring resistance while maintaining energy efficiency.
Solution Approach 2:
By positioning the motor higher than the generator, the system creates a gravitational potential difference that prevents oil from flowing back into the motor oil reservoir when the pump is stopped. The height difference establishes an equipotential barrier that maintains oil level separation without requiring additional active control mechanisms.
2Volume of moving object
If the motor and generator are disposed coaxially in the transverse direction with the same oil level, then the structure is compact, but the rotor becomes submerged in oil when the pump stops causing increased stirring resistance
Solution Approach 1:
The patent transitions from horizontal arrangement (coaxial in transverse direction) to vertical arrangement (stacked in longitudinal direction). This dimensional change maintains compact vehicle width while creating the necessary height difference to prevent oil backflow and stirring resistance in the motor.
Solution Approach 2:
The patent creates an asymmetric vertical positioning where the motor is placed higher than the generator. This asymmetric arrangement breaks the symmetry of oil levels that would otherwise cause both rotors to be submerged, selectively preventing oil backflow into the motor while maintaining compact overall structure.
3Ease of operation
If the motor is positioned higher than the generator in the longitudinal direction, then rotor submersion is prevented when the pump stops, but the device complexity increases due to vertical space requirements
Solution Approach 1:
The patent utilizes the vertical (longitudinal) dimension to solve the oil submersion problem, arranging the motor above the generator. This approach prevents rotor submersion through gravitational potential difference while using the available vertical space in the vehicle, avoiding the need for complex active control systems.
Solution Approach 2:
The patent combines the cooling systems of the motor and generator into a single integrated oil circulation system, with the oil pump serving both components. The vertical arrangement allows the same oil reservoir and pump to serve both devices while using gravity to prevent cross-contamination of oil levels, simplifying the overall system architecture.
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
Ensures efficient cooling of high-frequency operating motors without stirring resistance, even when the pressurizing unit is stopped, and reduces temperature variations in generators by optimizing coolant flow.
Implementation Method 1
an oil cooler 102 for cooling oil which cools the motor 100
Implementation Method 2
an oil pump 101 for pumping oil
Implementation Method 3
a cooling path in which a coolant for cooling the motor and the generator is recirculated
Data Source
AI summary
A cooling system to be mounted in a hybrid vehicle including a motor driven and a generator includes a cooling path and a pressurizing unit. In the cooling path, coolant for cooling the motor and the generator is recirculated. The pressurizing unit pumps the coolant. The motor is disposed downstream of the pressurizing unit in a recirculating direction of the coolant. The generator is disposed downstream of the motor and upstream of the pressurizing unit in the recirculating direction.