Mild Hybrid Starter Generator Engine Start Control
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Solution Overview
Problem
Mild hybrid electric vehicles experience prolonged engine start times in very cold weather due to inefficient engine starting mechanisms.
Innovation Solution
An apparatus and method that utilize a mild hybrid starter & generator (MHSG) with a stator and rotor, an ignition switch, external temperature detector, SOC detector, and controller to determine the optimal engine starting strategy based on temperature and battery state, ensuring simultaneous operation of the MHSG and starter when necessary to improve startability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If only the starter is used to start the engine in very cold weather, then the starting mechanism is simple, but the engine start time is prolonged and startability is reduced
Solution Approach 1:
The patent combines the starter and MHSG into a coordinated starting system where both motors operate simultaneously under cold temperature conditions. The controller activates both the starter and MHSG based on temperature detection, merging their torque output to improve engine startability and reduce start time in cold weather.
2Reliability
If the MHSG and starter operate simultaneously in cold weather, then engine startability is improved, but the control complexity increases
Solution Approach 1:
The system performs preliminary detection of external temperature and battery SOC before initiating the starting process. Based on these pre-detected conditions, the controller automatically determines whether to activate the starter alone or both the starter and MHSG simultaneously, eliminating the need for complex real-time decision-making during engine startup.
Solution Approach 2:
The controller continuously monitors external temperature and battery SOC, using this feedback information to adjust the starting strategy. When temperature is below the predetermined threshold and SOC is sufficient, the system activates both MHSG and starter; otherwise, it uses the starter alone, creating a closed-loop control system that adapts to environmental conditions.
3Measurement precision
If the MHSG is used to detect camshaft position for TDC determination, then the starting control precision is improved, but the device complexity increases
Solution Approach 1:
The MHSG wheel with teeth serves multiple functions: it acts as both the rotor component of the MHSG motor and the position sensing element for camshaft detection. The position detector mounted on the MHSG housing detects tooth positions to determine camshaft angle and TDC, eliminating the need for a separate position sensing system.
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 solution significantly improves engine startability in low temperatures by optimizing the engine starting process, ensuring faster and more efficient engine startup even in cold conditions.
Implementation Method 1
an MHSG position detector configured for detecting positions of the teeth
Implementation Method 2
a mild hybrid starter & generator (MHSG) including a stator and a rotor disposed inside the stator, and starting the engine or generating electricity according to an output of the engine
Data Source
AI summary
An apparatus for starting an engine of a mild hybrid electric vehicle may include: an ignition switch including a plurality of contact points; an external temperature detector configured for detecting an external temperature of the mild hybrid electric vehicle; an SOC detector configured for detecting a state of charge (SOC) of a battery; a mild starter & generator (MHSG) including a stator and a rotor disposed inside the stator, and starting the engine or generating electricity according to an output of the engine; a starter starting the engine; an MHSG wheel rotating integrally with the rotor, and having at least three teeth on a circumference thereof; an MHSG position detector configured for detecting positions of the teeth; and a controller determining a top dead center (TDC) of a predetermined cylinder based on a signal of the MHSG position sensor.