Electric Oil Pump Reverse Rotation to Eliminate Negative Pressure
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Solution Overview
Problem
High negative pressure inside the pump chamber of electric oil pumps, especially when shut down, leads to air entry and hindered oil circulation due to high viscosity oil conditions, particularly in cold temperatures.
Innovation Solution
The electric oil pump is controlled to rotate reversely by a predetermined angle, typically 360 degrees, before shutdown to reduce or eliminate negative pressure, preventing air entry and ensuring smooth oil circulation upon restart.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric oil pump is shut down directly without reverse rotation, then the shutdown response is fast and simple, but high negative pressure remains in the pump chamber causing air entry and poor oil circulation
Solution Approach 1:
The patent applies preliminary action by rotating the pump in reverse direction before shutdown to eliminate negative pressure in the pump chamber. This preliminary reverse rotation prevents air from being sucked into the pump chamber through the intake port, ensuring reliable oil supply when the pump restarts, especially under high viscosity conditions.
2Reliability
If the pump rotates reversely before shutdown, then negative pressure is reduced and air entry is prevented, but the control complexity increases
Solution Approach 1:
The control unit automatically determines when reverse rotation is needed by monitoring pump operation status and oil viscosity conditions. The system self-manages the reverse rotation control without requiring external intervention or complex additional devices, simply using the existing motor control capability to rotate the pump in reverse direction for a predetermined angle before shutdown.
3Productivity
If reverse rotation is implemented, then immediate smooth oil circulation is achieved upon restart, but energy consumption increases
Solution Approach 1:
The patent applies partial action by rotating the pump in reverse direction for only a predetermined angle (not a full 360 degrees) before shutdown. This partial reverse rotation is sufficient to eliminate negative pressure and prevent air entry, achieving the goal of smooth oil circulation upon restart while minimizing unnecessary energy consumption compared to continuous or excessive reverse rotation.
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 approach effectively prevents air from entering the pump chamber and allows for immediate smooth oil supply and circulation, even at high viscosity coefficients, without the need for additional pressure measurement devices.
Implementation Method 1
the oil 40 is taken into the pump chamber through the intake side 31 and negative pressure is generated inside the pump chamber
Implementation Method 2
the motor 12 is caused to rotate reversely by a predetermined angle in a direction opposite to the rotation direction during supply of the oil 40
Data Source
Figure 1~2
Figure 3
Figure 4(a)~4(e)
AI summary
The objective of the present invention is to provide an oil supply device in which a negative pressure in a pump chamber is reduced or eliminated when an electric oil pump is shut down, thereby preventing air from entering the pump chamber and allowing oil to be supplied or recirculated smoothly. This oil supply device (10) includes: an electric oil pump (11) in which a rotary volumetric change pump (20) provided with an inner rotor (21) and an outer rotor (22) is caused to operate by means of a motor (12); and an electric oil pump controller (13) which controls the motor in such a way that, when the electric oil pump (11) is to be shut down, the rotary volumetric change pump (20) is caused to temporarily stop, after which the rotary volumetric change pump (20) is caused to rotate by a predetermined angle in the opposite direction to the direction of rotation during oil supply, and is then shut down.