Idle Stop-and-Go System Crankshaft Position Control
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Solution Overview
Problem
Modern vehicle idle stop-and-go systems face inefficiencies during engine restart, requiring high torque and energy to restart the engine, leading to increased vibration and reduced energy efficiency.
Innovation Solution
A vehicle system that includes a controller to manage the crankshaft position by applying calculated electric loads through an alternator, using a capacitor and battery to optimize engine restart torque and reduce energy consumption, with modes such as brake-recuperation, capacitor restart, and battery restart to enhance fuel efficiency and smooth restarts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the starter motor generates greater torque to restart the engine at top-dead-center of compression stroke, then the engine can be restarted successfully, but the energy efficiency decreases and vibration increases
Solution Approach 1:
The system applies electric load to the alternator during idle stop mode to advance the crankshaft position before restart, preparing the engine to be in a more favorable position (away from top-dead-center of compression stroke) when the starter motor operates, thereby reducing the torque and energy required for successful restart
2Reliability
If the starter motor generates greater torque to restart the engine, then the engine can be restarted successfully, but the vibration of the engine increases
Solution Approach 1:
The system uses the alternator with applied electric load to advance the crankshaft position before restart, ensuring the engine is positioned away from top-dead-center of compression stroke when restart occurs, thereby reducing the torque spike and associated vibration during starter motor operation
3Loss of energy
If the engine stops with piston at top-dead-center of compression stroke, then the idle stop mode is achieved, but the starting torque requirement increases significantly
Solution Approach 1:
During idle stop mode, the system applies electric load to the alternator to advance the crankshaft position from top-dead-center of compression stroke to a more favorable position, thereby preparing the engine for easier restart and reducing the starting torque requirement when restart is needed
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 system reduces engine restart torque and energy consumption, minimizing vibration and improving fuel efficiency by precisely controlling the crankshaft position and utilizing stored electric power effectively.
Implementation Method 1
an alternator operatively connected to the crankshaft of the engine and configured to generate electric power
Implementation Method 2
a capacitor electrically connected to the alternator, the battery, and the starter motor, and configured to store the generated electric power based on a state of charge (SOC) of the battery and capacitor
Implementation Method 3
a starter motor electrically connected to a battery and configured to start the engine
Data Source
AI summary
The present disclosure provides a vehicle system including: an engine having a crankshaft to generate power; a starter motor electrically connected to a battery to start the engine; an alternator operatively connected to the crankshaft of the engine so as to generate electric power and charge the battery; a capacitor electrically connected to the alternator, the battery, and the starter motor, and enable to store the generated electric power based on a state of charge (SOC) of the battery and capacitor; and a controller to control electric connections between the alternator, the capacitor, the battery, and the starter motor. In particular, the controller determines an idle stop mode and controls a position of the crankshaft by applying a calculated electric load to the alternator such that the crankshaft position is located in a predetermined range.