Brushless Electric Starter Motor Control for Engine Cranking
Solution Overview
Problem
Current starter systems for powertrains face challenges in achieving efficient and quick engine starts and restarts while minimizing voltage dip and maintaining compact packaging, especially during engine autostop events in vehicles.
Innovation Solution
A starter system utilizing a brushless electric starter motor with a power inverter, solenoid, and electronic control system that selectively engages the pinion gear with the crankshaft, allowing for efficient cranking and restarts without supplemental power boosting, by determining engine speed and enabling the starter motor only when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a brush-type starter motor is used, then the engine can be cranked, but the start time is longer and voltage dip occurs due to high current draw
Solution Approach 1:
The patent replaces the traditional brush-type electrical starter motor with a brushless electrical starter motor. This substitution eliminates carbon brushes and commutators, using permanent magnets and electronic control instead. The brushless design reduces electrical resistance and energy losses, resulting in lower current draw during cranking while delivering higher torque and faster engine start times, directly resolving the contradiction between speed improvement and energy consumption.
2Productivity
If a brushless electric starter motor is used, then engine start time is reduced and current draw is lowered, but the system complexity increases due to power inverter and electronic control
Solution Approach 1:
The brushless starter motor is designed to serve multiple functions: it acts as both a starter motor during engine cranking and as a generator during engine operation. The power inverter and electronic control system enable the motor to operate in different modes (motoring and generating) based on system needs. This multi-functionality justifies the increased complexity by providing additional capabilities beyond simple starting, improving overall system efficiency and enabling energy recovery during braking.
3Volume of moving object
If traditional starter motor packaging is used, then space is occupied, but the brushless motor allows for more efficient space utilization
Solution Approach 1:
The brushless starter motor system integrates multiple components into a compact nested arrangement. The power inverter is positioned to work in conjunction with the motor, and the electronic control system is integrated within the starter assembly. This nested configuration allows the brushless motor system to occupy similar packaging space as traditional starters while providing superior performance, effectively resolving the contradiction between volume reduction and manufacturing complexity.
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 brushless electric starter motor provides quicker and more consistent engine starts with reduced current draw, eliminating voltage dips and allowing for smaller, more efficient packaging without the need for additional power boosting, enhancing fuel economy and performance.
Implementation Method 1
a power inverter operable to convert direct current provided from the battery power pack to multi-phase alternating current to drive the brushless electric starter motor
Implementation Method 2
a solenoid operatively connected to the pinion gear, and further includes an electronic control system that is operable to control the brushless electric starter motor
Implementation Method 3
The brushless electric starter motor may provide advantages such as a long life-cycle, a relatively low inertia, and consistent and quick engine starts and restarts
Data Source
AI summary
A starter system includes a brushless electric starter motor and a battery power pack, the motor operatively connectable to an internal combustion engine of a powertrain. A power inverter converts direct current provided from the battery power pack to multi-phase alternating current to drive the motor. A pinion gear with one-way clutch is rotatably driven by the motor and movable between a disengaged position and an engaged position in which the pinion gear is meshingly engaged with a ring gear operatively connected to a crankshaft of the engine. A solenoid is operatively connected to the pinion gear. An electronic control system controls the motor to crank the engine using power provided from the battery power pack, and to separately command the solenoid to a disabled or an enabled state. A method of controlling the starter system controls the motor to crank the engine in a restart following an autostop.