Hybrid Starter Generator Torque Control for Engine Clutch Shock
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Solution Overview
Problem
In hybrid electric vehicles, the motor cannot accurately compensate for transmission torque of the engine clutch during fuel cut-off, leading to clutch slip and shock due to engine friction torque, as the transmission torque cannot be calculated accurately.
Innovation Solution
A method and apparatus that control the engine clutch of a hybrid electric vehicle by determining the need to release the clutch, calculating engine friction torque, increasing the output torque of an integrated hybrid starter and generator (HSG) by the absolute value of the friction torque, and releasing the clutch when the HSG torque matches the friction torque, while also decreasing motor torque and adjusting HSG output torque accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the motor performs torque compensation by reflecting transmission torque of the engine clutch, then shock can be prevented, but the torque compensation cannot be controlled accurately because transmission torque cannot be calculated accurately
Solution Approach 1:
The patent replaces the mechanical torque transmission system with an electrical system. The HSG motor provides electrical torque compensation instead of relying on mechanical torque calculation and transmission through the clutch. This substitution eliminates the need for accurate transmission torque calculation while achieving effective shock prevention through direct electrical torque control.
Solution Approach 2:
The HSG motor acts as an intermediary between the engine and the drivetrain. It provides a controllable torque source that can compensate for clutch slip and shock without requiring direct measurement or calculation of transmission torque. The HSG serves as a mediator that decouples the torque transmission path while maintaining torque balance.
2Loss of energy
If the engine clutch is released during fuel cut-off operation, then fuel efficiency is improved, but clutch slip occurs due to hydraulic pressure decrease and shock occurs due to engine friction torque
Solution Approach 1:
The HSG motor applies preliminary counter-torque to offset the engine friction torque before the clutch is fully released. By calculating the friction torque and applying an equal and opposite torque through the HSG, the system prevents clutch slip and shock from occurring in the first place, enabling clean clutch disengagement during fuel cut-off operation.
Solution Approach 2:
The patent replaces the purely mechanical clutch engagement/disengagement system with an electro-mechanical system. The HSG motor provides controlled torque to manage clutch release, replacing reliance on hydraulic pressure alone and eliminating the harmful effects of uncontrolled clutch slip and shock.
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 prevents shock from engine friction torque, improves drivability, reduces fuel consumption, and minimizes fuel injection, thereby enhancing fuel efficiency and reducing exhaust emissions.
Implementation Method 1
an integrated hybrid starter and generator (HSG) configured to start the engine or generate power by an engine torque
Implementation Method 2
an electric motor which generates torque from an electric battery
Implementation Method 3
an engine which generates torque from fuel combustion
Data Source
AI summary
An apparatus and a method for controlling an engine clutch of a hybrid electric vehicle control a torque of an input shaft of the engine clutch to 0 by using an integrated hybrid starter and generator (HSG) and releases the engine clutch. The method may include: determining whether a release of the engine clutch is required while the hybrid electric vehicle is operating with fuel cut off; calculating an engine friction torque; increasing an output torque of the HSG by an absolute value of the calculated engine friction torque; decreasing a motor torque corresponding to the output torque of the HSG; and releasing the engine clutch when the output torque of the HSG is equal to the engine friction torque.