Engine Starting System Controller Timing for Noise Reduction
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Solution Overview
Problem
Integrated starter generator (ISG) systems for internal combustion engines face challenges in efficiently starting the engine while maintaining fuel economy, as the overlap period between starter driving and power running modes can lead to either deteriorated fuel consumption due to redundant activation or increased output torque.
Innovation Solution
An engine starting system that controls a gear-connected starter and a belt-connected motor-generator, where a controller activates the starter, recognizes the motor-generator's rotation, and deactivates the starter before the rotational angular position reaches the compression top dead center, ensuring efficient starting and reducing gear noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the starter is activated to rotate the engine, then the engine can be started, but gear noise is generated due to pinion engagement with the ring gear
Solution Approach 1:
The patent utilizes the compression TDC position as a beneficial reference point to time the deactivation of the starter. By deactivating the starter precisely at compression TDC, the system converts the potentially harmful gear noise into a controlled event that occurs only during the necessary starting phase, while the belt-connected motor-generator takes over smoothly without engagement noise.
2Reliability
If the starter and motor-generator operate with an overlap period, then seamless transition is achieved, but fuel consumption deteriorates due to redundant activation
Solution Approach 1:
The patent implements preliminary action by having the motor-generator start rotating during the starter driving period, before the starter is deactivated. The motor-generator is prepared in advance to take over the torque application, ensuring a smooth transition while allowing the starter to be deactivated at the optimal moment (compression TDC) to minimize redundant operation and fuel consumption.
3Reliability
If the motor-generator starts operating during the starter driving period, then seamless transition is achieved, but the output torque of the motor-generator must be increased
Solution Approach 1:
The patent applies partial action by having the motor-generator provide supplementary torque during the overlap period rather than requiring it to provide full torque from the start. The starter continues to provide the majority of the torque needed for engine cranking, while the motor-generator contributes partially to ensure smooth transition, thereby avoiding the need for excessive motor-generator output torque.
4Use of energy by moving object
If the starter is deactivated early, then fuel economy is improved, but the motor-generator may not be ready to take over
Solution Approach 1:
The patent implements preliminary action by activating the motor-generator during the starter driving period, before the starter is deactivated. This ensures that the motor-generator is already rotating and ready to take over torque application immediately when the starter is deactivated at compression TDC, maintaining both fuel economy 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
This approach reduces gear noise and ensures proper overlap between starter and motor-generator operation, enhancing engine startability and fuel economy by optimizing the timing of starter deactivation and motor-generator activation.
Implementation Method 1
Recognize rotation of a rotor of the motor-generator resulting from drive of the engine by the starter
Data Source
AI summary
In an engine starting system, a first controller activates, in response to a driver's starting request, a first starting device to rotate the rotating shaft of an engine. A second controller is communicably connected to the first controller. The second controller recognizes rotation of the rotor of a second starting device resulting from an activation of the first starting device. The second controller starts a power running operation of the second starting device based on the recognition of the rotation of the rotor. The first controller determines whether the power running operation of the second starting device has been started. The first controller deactivates, when it is determined that the power running operation has been started, the first starting device before a rotational angular position of the rotating shaft of the engine arrives at a compression top dead center of the engine.