Electric Oil Pump Controller Reducing Restart Heat
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Solution Overview
Problem
The electric oil pump in vehicles experiences repeated restarts due to insufficient power supply and high heat generation, leading to increased power consumption and reduced service life, especially when operated in sensorless mode without positional sensors.
Innovation Solution
A controller for the electric oil pump that implements a preoperation mode with a low target rotational speed and shifts to a determination mode based on actual rotational speed and current thresholds, limiting restarts according to the pump's operation history to reduce power consumption and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the electric oil pump is rotated at a high preoperation rotational speed to prepare for operation in advance, then the oil temperature rises and viscosity decreases, but current at extremely low temperature increases excessively, leading to high power consumption and heat generation
Solution Approach 1:
The system performs preliminary action by rotating the electric oil pump at a low preoperation rotational speed before actual operation to gradually raise oil temperature and reduce viscosity, preparing the system for subsequent high-speed operation while avoiding excessive current draw at extremely low temperatures
Solution Approach 2:
The system dynamically adjusts the rotational speed of the electric oil pump based on operating conditions, transitioning from a low preoperation rotational speed to a higher operational speed as needed, rather than maintaining a fixed high speed that would cause excessive power consumption and heat generation
2Reliability
If the electric oil pump is restarted repeatedly due to insufficient power supply or high heat generation, then operational readiness is maintained, but power consumption increases and service life is reduced
Solution Approach 1:
The system uses feedback mechanisms to monitor the operation history of the electric oil pump, including the number of restarts and operational parameters, and uses this information to control future restart operations, preventing excessive restarts that would reduce service life while maintaining operational readiness
Solution Approach 2:
Instead of repeated restarts, the system implements periodic preoperation rotation at a low speed to maintain operational readiness, reducing the frequency of full restart cycles and thereby extending the service life of the electric oil pump
3Device complexity
If the electric oil pump operates in sensorless mode without positional sensors, then device complexity is reduced, but positioning control during restart becomes difficult, requiring large current
Solution Approach 1:
The system performs preliminary positioning control at a low preoperation rotational speed before full operation, which reduces the current required for positioning in sensorless mode, thereby maintaining the simplicity of sensorless operation while reducing energy consumption during restart
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
The controller reduces the number of electric oil pump restarts, conserving power and extending the service life by optimizing operational conditions and minimizing heat generation.
Implementation Method 1
a motor M and an inverter INV that executes pulse width modulation (PWM) control over motor M
Implementation Method 2
a pump unit P and a motor M for driving the pump unit P, wherein the pump unit P is configured to pump oil from an oil pan to a transmission
Implementation Method 3
an inverter INV that executes pulse width modulation (PWM) control over motor M
Data Source
AI summary
An electric oil pump (ELOP) provided in parallel to a mechanical oil pump driven by an engine supplies oil to a clutch of a transmission. The ELOP is rotated in advance of a request to operate the ELOP at a targeted relatively-low first preoperation rotational speed. When an actual rotational speed matches the first preoperation rotational speed and an actual current matches a threshold, the ELOP is rotated at a targeted relatively-high second preoperation rotational speed. At least when an actual rotational speed matches a second predetermined rotational speed not higher than the second preoperation rotational speed, it is determined that preoperation is completed. If the number of restarts during the preoperation as one operation history of the ELOP reaches or exceeds the predetermined number of times, the current supply to the ELOP is interrupted to limit the restart, thereby reducing the number of repeated restarts of the ELOP.