MHSG Wheel Teeth for Engine Restart Without Position Sensors
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Solution Overview
Problem
Mild hybrid electric vehicles face challenges in starting the engine when camshaft or crankshaft position sensors malfunction, as existing systems rely on these sensors to determine fuel injection timing and cylinder position, leading to engine shutdown and delayed restarts.
Innovation Solution
An apparatus and method utilizing a mild hybrid starter & generator (MHSG) wheel with unique teeth configurations and a position detector to determine top dead center, allowing the controller to control engine operations independently of faulty sensors, enabling engine start without delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If camshaft position sensor or crankshaft position sensor is used to detect cylinder position and engine rotation speed, then the engine can be controlled properly, but the engine cannot be restarted when these sensors malfunction
Solution Approach 1:
The MHSG wheel acts as an intermediary component between the MHSG motor and the engine crankshaft. By attaching the MHSG wheel to the crankshaft and using its teeth as a reference, the system can determine TDC position and control engine restart without relying on the camshaft position sensor or crankshaft position sensor, thus resolving the contradiction between reliability and device complexity
Solution Approach 2:
The MHSG wheel serves multiple functions: it transmits rotational motion from the MHSG motor to the crankshaft, provides a reference for detecting TDC position through its teeth, and enables engine restart control. This multi-functionality reduces dependency on separate sensors, improving reliability while managing device complexity
2Productivity
If traditional sensor-based system is used to determine top dead center and fuel injection timing, then precise control is achieved, but engine restart is delayed when sensors fail
Solution Approach 1:
The MHSG wheel is pre-attached to the crankshaft with its teeth positioned to correspond with specific cylinder positions. When the MHSG motor rotates the crankshaft, the teeth pass by the MHSG position detector, which preliminarily identifies the TDC position before fuel injection occurs. This preliminary action enables immediate engine restart without delay, improving both productivity and reliability
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
Enables the engine to start promptly even if camshaft or crankshaft position detectors are defective, ensuring continuous operation by using the MHSG position detector to determine cylinder position and control engine operations.
Implementation Method 1
an MHSG position detector detecting a plurality of positions of the teeth
Implementation Method 2
a mild hybrid starter & generator (MHSG) including a stator and a rotor internally disposed within 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; a mild hybrid starter & generator (MHSG) including a stator and a rotor internally disposed within the stator, and starting the engine or generating electricity according to an output of 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 configured for determining a top dead center (TDC) of a predetermined cylinder according to a signal of the MHSG position detector, and rotating the MHSG to start the engine.