Driving Motor Cooling via Engine Oil Pump During Locked Rotor
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Solution Overview
Problem
In hybrid vehicles without an electric oil pump, a locked rotor condition during electric mode leads to low vehicle speed, resulting in insufficient coolant supply to the driving motor, which reduces its service life or causes it to burn out due to inadequate cooling.
Innovation Solution
A method and device that initiate the engine to drive the engine end oil pump and coolant flow path to cool the driving motor when a locked rotor condition is detected, adjusting the auxiliary cooling starting temperature and controlling the cooling fan and spill valve to ensure effective heat dissipation, thereby preventing overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the wheel end oil pump is used to cool the driving motor in electric mode, then the cooling system is simpler and energy consumption is reduced, but when locked rotor occurs the coolant supply becomes insufficient
Solution Approach 1:
The engine end oil pump is designed to serve dual functions: during engine mode it provides lubrication for the engine, and during electric mode with locked rotor it provides cooling for the driving motor. This multi-functionality resolves the contradiction by enabling a single pump to handle both reliability requirements without adding separate dedicated cooling equipment.
Solution Approach 2:
The engine end oil pump acts as an intermediary resource that can be activated to provide cooling capacity when the primary wheel end oil pump becomes insufficient. By controlling the engine to run and redirecting its oil pump output to the driving motor cooling circuit, the system mediates between the limited cooling capacity of the wheel end pump and the high heat dissipation requirements during locked rotor conditions.
2Reliability
If the engine is started to cool the driving motor during locked rotor, then sufficient coolant supply is ensured, but energy consumption increases and engine wear occurs
Solution Approach 1:
The system monitors temperature and locked rotor conditions in advance, and starts the engine proactively before the driving motor temperature reaches critical levels. By initiating cooling action early through engine start, the system prevents overheating while avoiding unnecessary prolonged engine operation, thus balancing reliability with energy consumption.
Solution Approach 2:
The control system continuously monitors the driving motor temperature and locked rotor status, and dynamically controls engine operation based on this feedback. When locked rotor is detected and temperature exceeds thresholds, the engine is started to provide cooling; when temperature drops below thresholds, the engine is stopped. This feedback mechanism ensures the engine runs only when necessary, minimizing energy consumption while maintaining adequate cooling.
3Reliability
If the auxiliary cooling starting temperature is lowered to ensure adequate cooling, then the driving motor is protected from overheating, but the engine starts more frequently increasing energy consumption
Solution Approach 1:
The system dynamically adjusts the auxiliary cooling starting temperature parameter based on the duration of locked rotor conditions. When locked rotor duration is short, a higher temperature threshold is used to avoid unnecessary engine starts. When locked rotor duration is extended, the threshold is lowered to ensure adequate cooling. This parameter adaptation resolves the contradiction by optimizing the trade-off between overheating protection and energy consumption under different operating conditions.
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 solution ensures sufficient coolant supply to the driving motor, preventing overheating and extending its service life by actively cooling the motor during locked rotor conditions in electric mode, even at low vehicle speeds.
Implementation Method 1
the engine end oil pump to drive a coolant in the cooling flow path to cool the driving motor
Implementation Method 2
a rotation speed of a cooling fan of the vehicle is increased to cool the driving motor
Data Source
AI summary
A method for cooling a driving motor with a locked rotor of a vehicle is disclosed. The vehicle includes the driving motor, an engine, an engine end oil pump, and a cooling flow path. The engine is configured to drive the engine end oil pump, and the cooling flow path connects the engine end oil pump to the driving motor. The method includes: in response to determining that a driving mode of the vehicle is an electric mode and that the vehicle meets a locked rotor motor trigger condition, and detecting that a current temperature of the driving motor is greater than an auxiliary cooling starting temperature of the engine, controlling the engine to start to cause the engine end oil pump to drive a coolant in the cooling flow path to cool the driving motor.