Hybrid Engine Start Clutch Control for Smooth Torque Transition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hybrid electric vehicles experience torque fluctuations and jerking during transitions from electric drive mode to hybrid drive mode, leading to an unsettling ride and potential drivetrain loading, as existing solutions have not adequately addressed these issues.
Innovation Solution
A technique involving a clutch control system that slips to rotate the engine, then disengages to fuel the engine and synchronize speeds with the electromechanical device before fully engaging, ensuring smooth transitions and maintaining driver torque demand.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electromechanical device torque is reduced to start the engine, then the engine can be started, but the driver feels reduced torque at the wheels and the vehicle may jerk
Solution Approach 1:
The clutch is slipped in advance to gradually accelerate the engine crankshaft to near-operating speed before full engagement, preventing sudden torque changes. This preliminary action prepares the engine for smooth coupling with the electromechanical device, eliminating jerks and maintaining driver comfort during the transition from electric to hybrid drive mode.
2Reliability
If the transmission is disengaged or slipped during engine starting, then the engine can be started without affecting drive wheels, but the driver feels reduced torque and the transition is not smooth
Solution Approach 1:
The clutch engagement is made dynamic and progressive rather than static or abrupt. The clutch slip ratio is continuously adjusted during the starting process, allowing the engine speed to smoothly track the electromechanical device speed. This dynamic control maintains vehicle speed stability and eliminates the unsettling sensations experienced by the driver during mode transitions.
3Productivity
If the engine speed does not match the electromechanical device speed at engagement, then the engine can be started quickly, but torque oscillations and jerking occur during transition
Solution Approach 1:
The engine crankshaft is preliminarily accelerated to a speed close to the electromechanical device operating speed through controlled clutch slip before full engagement. This preliminary speed matching prevents large speed differentials at the moment of coupling, thereby eliminating torque oscillations and jerking sensations while maintaining efficient engine starting performance.
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 minimizes torque oscillations and jerk, providing a smoother ride and maintaining vehicle speed stability during transitions, thus enhancing fuel economy and reducing drivetrain stress.
Implementation Method 1
slipping a clutch between the engine and the electromechanical device with the vehicle in the electric drive mode to rotate the engine
Implementation Method 2
disengaging the clutch so that the engine is fueled to obtain a speed that approximates the speed of the electromechanical device
Data Source
AI summary
An engine starting system and technique for transitioning from an electric drive mode to a hybrid drive made in a hybrid electric vehicle is disclosed. In an electric drive mode the torque demand of the hybrid electric vehicle is met by an electromechanical device. The starting technique includes slipping a clutch between the engine and electromechanical device with the vehicle in the electric drive mode to rotate the engine, disengaging the clutch so that the engine is fueled to obtain a speed that approximates a speed of the electromechanical device, and engaging the clutch to couple the engine and the electromechanical device to the drive shaft to meet driver torque demand.