Brushless Motor Rotor Pre-positioning for Rapid Engine Start
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Solution Overview
Problem
Internal combustion engines in stop-start systems of motor vehicles face challenges in rapid and efficient restarting, particularly when the engine is shut off and needs to be quickly reactivated to maintain fuel efficiency and reduce emissions.
Innovation Solution
A method utilizing a brushless electric motor with a stator and rotor, controlled by an electronic controller, which determines the angular position of the rotor and applies electrical current to achieve a predetermined torque for rapid engine starting, incorporating Hall effect sensors and a quadrature encoder for precise positioning and speed management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the engine is shut off to maximize fuel efficiency and reduce emissions, then fuel consumption and emissions are reduced, but the engine cannot be quickly restarted
Solution Approach 1:
The system determines the present angular position of the rotor relative to the stator before starting the engine, and pre-positions the rotor to a predetermined starting angular position that provides maximum torque. This preliminary positioning action ensures the engine can be restarted as quickly as possible while maintaining fuel efficiency benefits during coasting or idling periods.
2Speed
If electrical current is applied to the electric motor to generate maximum torque, then the engine can be restarted quickly, but the electrical energy consumption increases
Solution Approach 1:
The controller applies electrical current to the motor windings in a specific sequence based on the determined angular position of the rotor, creating a rotating magnetic field that generates maximum torque. The system also dynamically adjusts voltage and current parameters during the starting process, and shorts the multi-phase windings when rotor speed exceeds maximum speed to recover energy and reduce overall electrical consumption.
Solution Approach 2:
The system uses Hall effect sensors and a quadrature encoder to continuously monitor the angular position and speed of the rotor, providing feedback to the controller. Based on this feedback, the controller adjusts the electrical current application to optimize torque generation while minimizing energy consumption, and determines when to short the windings for energy recovery.
3Speed
If the rotor is positioned to generate maximum torque, then the engine can be started rapidly, but the complexity of the control system increases
Solution Approach 1:
The system replaces traditional mechanical starting mechanisms with an electric motor-driven pinion gear system controlled by electronic sensors and a controller. The controller determines rotor angular position using Hall effect sensors and quadrature encoders, then applies electrical current to position the rotor for maximum torque, eliminating complex mechanical timing and positioning mechanisms.
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 rapid and efficient restarting of the internal combustion engine, optimizing fuel efficiency and reducing emissions by ensuring quick and reliable engine reactivation in stop-start scenarios.
Implementation Method 1
A starter assembly having a brushless electric motor including a stator and a rotor and configured to drive a pinion gear
Implementation Method 2
The starter assembly may include a quadrature encoder and at least one Hall effect sensor, each in electrical communication with the controller. In such an embodiment, the determining of the present angular position of the rotor relative to the stator may include initially detecting the angular position of the rotor in low resolution via the at least one Hall effect sensor
Data Source
AI summary
A method of rapid starting an internal combustion engine includes determining that the engine is stopped and detecting an engine start request. The method also includes enabling a starter assembly having a brushless electric motor including a stator and a rotor and configured to drive a pinion gear, and engaging the pinion gear with the engine flywheel. The method also includes determining a present angular position of the rotor relative to the stator configured to generate a first rotor torque. The method additionally includes applying an electrical current to the motor, in response to the determined angular position of the rotor, to turn the rotor to a predetermined starting angular position configured to provide a second torque that is greater than the first torque. Furthermore, the method includes commanding the motor to spin the rotor and thereby apply the second torque via the pinion gear to start the engine.