Crankshaft-Angle Engine Starting With Torque-Staged ETM Control
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Solution Overview
Problem
Existing internal combustion engine starting systems, particularly in small vehicles like snowmobiles, face challenges with weight, fuel efficiency, and handling due to the use of electric starting systems, and require a method to efficiently manage the torque and voltage of motor-generator units during starting and generating operations.
Innovation Solution
A system and method utilizing an electric turning machine connected to the crankshaft, with a sensor providing absolute angular position data to a controller, which calculates and delivers torque levels to efficiently start the engine by rotating the crankshaft, optimizing torque delivery to overcome compression and manage voltage during engine startup and operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an electric starting system with battery and starter is used, then the engine can be started conveniently, but the vehicle weight increases and fuel efficiency decreases
Solution Approach 1:
The patent combines the starter and generator into a single motor-generator unit that is directly coupled to the crankshaft. This integrated unit serves dual functions: acting as a starter motor to crank the engine during starting, and as a generator to produce electrical power during engine operation, thereby eliminating the need for separate battery-starter and generator systems and reducing overall vehicle weight.
Solution Approach 2:
The motor-generator unit is designed to perform multiple functions: it operates as an electric motor during engine starting to rotate the crankshaft, and subsequently operates as an electric generator during engine operation to generate electrical power. This multi-functional design replaces traditional single-function components (starter and generator) with a universal unit, reducing system complexity and weight.
2Reliability
If a motor-generator unit is sized to provide sufficient starting torque, then the engine can be reliably started, but the unit generates excessive voltage at high rotational speeds
Solution Approach 1:
The patent implements dynamic control of the motor-generator unit through electronic control that adjusts its operating characteristics based on real-time conditions. During starting, the controller optimizes torque delivery to reliably crank the engine. During generating operation, the controller dynamically regulates voltage output to match electrical system requirements, preventing excessive voltage generation at high rotational speeds while maximizing electrical power production.
Solution Approach 2:
The controller modifies operational parameters of the motor-generator unit based on its operating mode. In motor mode during starting, parameters are optimized for high torque output. In generator mode during operation, parameters are adjusted to control voltage output and maximize electrical power generation, thereby resolving the contradiction between reliable starting and excessive voltage generation.
3Power
If the motor-generator unit operates at high rotational speeds as a generator, then electrical power is produced, but voltages far exceed the needs of vehicle components
Solution Approach 1:
The patent implements a feedback control system that continuously monitors the electrical output of the motor-generator unit and compares it with the actual electrical power needs of the vehicle. The controller uses this feedback information to dynamically adjust the generator's output characteristics, ensuring that voltage and power delivery match the requirements of electrical components while preventing excessive voltage generation during high-speed operation.
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
This approach enables a lighter and more efficient electrical start procedure, reducing the weight and assembly complexity of starting systems while improving fuel efficiency and handling, and effectively manages torque and voltage to enhance engine starting and operation.
Implementation Method 1
The motor-generator unit can be used as a starter or as a generator. By applying current to the motor-generator unit, the motor-generator unit operates as a starter and turns the crankshaft to enable starting of the engine. When the motor-generator is operated as a generator, the rotation of the crankshaft causes the motor-generator to generate electricity.
Implementation Method 2
In order to start the engine, the torque applied to the crankshaft to make it turn has to be sufficiently large to overcome the compression inside the engine's cylinders resulting from the pistons moving up in their respective cylinders as the crankshaft rotates.
Data Source
AI summary
A method and a system for starting an internal combustion engine (ICE) having a crankshaft and an electric turning machine (ETM) operatively connected to the crankshaft are disclosed. An absolute angular position of the crankshaft related to a top dead center position of a piston in a combustion chamber of the ICE is determined. Electric power is delivered to the ETM at a first level to rotate the crankshaft. Electric power is then delivered to the ETM at a second level greater than the first level when the piston reaches a predetermined position before the TDC position. Fuel is injected in the combustion chamber after the piston has passed beyond the TDC position. The fuel is then ignited. In an implementation, the ICE is started in less than 110 degrees of rotation of the crankshaft.