Hybrid Vehicle Electric Oil Pump Control for Clutch Protection
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Solution Overview
Problem
Hybrid vehicles with only an electric oil pump face challenges in maintaining hydraulic pressure to prevent damage to the engine clutch due to centrifugal force, especially during deceleration or gear shifts, which can lead to reduced energy efficiency and clutch durability.
Innovation Solution
A method for controlling the electric oil pump (EOP) that adjusts its RPM based on the vehicle's deceleration mode and gear shifts, adding an additional RPM to ensure sufficient flow rate of automatic transmission fluid to the balance chamber of the engine clutch, thereby preventing damage and improving durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the electric oil pump is driven at minimum RPM to improve energy efficiency, then energy efficiency is improved, but the flow rate of ATF supplied to the balance chamber becomes insufficient causing engine clutch damage
Solution Approach 1:
The EOP control system dynamically adjusts the pump's operating state based on real-time vehicle conditions. The controller monitors turbine RPM and automatically increases EOP speed from minimum RPM to a higher RPM when turbine RPM exceeds a predetermined threshold, ensuring adequate ATF flow to the balance chamber only when necessary to prevent clutch damage while minimizing energy consumption during normal operation
Solution Approach 2:
The system changes the operating parameters of the EOP based on turbine RPM conditions. When the turbine RPM is below the threshold, the EOP operates at minimum RPM for energy efficiency. When turbine RPM exceeds the threshold, the controller increases EOP RPM to provide additional ATF flow rate to the balance chamber, thereby preventing clutch pack damage while maintaining energy efficiency during normal operation
2Reliability
If the electric oil pump operates continuously at high RPM to ensure sufficient hydraulic pressure, then engine clutch protection is improved, but energy consumption increases
Solution Approach 1:
Instead of continuous high-RPM operation, the system uses periodic or conditional high-RPM operation triggered only when turbine RPM exceeds the predetermined threshold. The controller monitors the threshold condition and activates high-RPM EOP operation only during these specific periods, thereby providing clutch protection when needed while minimizing overall energy consumption
Solution Approach 2:
The system applies partial action by increasing EOP RPM only to the extent necessary to provide sufficient ATF flow to the balance chamber during high-turbine-RPM conditions, rather than maintaining continuously excessive high RPM. This targeted intervention provides adequate clutch protection while avoiding unnecessary energy consumption during normal 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 approach enhances the energy efficiency of hybrid vehicles by minimizing EOP operation while ensuring adequate hydraulic pressure, reducing the risk of engine clutch damage and improving its durability.
Implementation Method 1
an electric oil pump (EOP) configured to generate the hydraulic pressure of oil to facilitate operation, lubrication and cooling of a transmission
Implementation Method 2
a piston moves forwards due to applied hydraulic pressure and thus generates frictional force towards a plurality of clutch packs
Implementation Method 3
generates frictional force towards a plurality of clutch packs
Implementation Method 4
the piston moves backwards due to a return spring and thus releases the frictional force from the clutch packs
Implementation Method 5
the oil remaining in the engine clutch causes the piston to undesirably pressurize the clutch packs due to centrifugal force
Data Source
AI summary
A method for controlling an electric oil pump (EOP) of a hybrid vehicle may include determining whether or not the hybrid vehicle is in a decelerating situation in an EV mode, driving the EOP at an RPM at a point L, corresponding to a minimum RPM of the EOP to form a target line pressure of a transmission, upon determining that the hybrid vehicle is decelerating in the EV mode, determining whether or not an RPM of a turbine is equal to or greater than a predetermined reference RPM, and driving the EOP at an RPM acquired by adding a predetermined additional RPM to secure an additional flow rate of automatic transmission fluid supplied to a balance chamber of an engine clutch to the RPM at the point L, upon determining that the RPM of the turbine is equal to or greater than the predetermined reference RPM.