Three-Cylinder Engine Stop Control for Vibration Reduction
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Solution Overview
Problem
In three-cylinder internal combustion engines, the variability in the cylinder brought into compression stroke at engine stop causes precession, leading to vibrations during startup, which are exacerbated by the phase of torque application to the crankshaft, resulting in significant vibrations.
Innovation Solution
A control apparatus that manages the electric motor's output torque to stop the engine with a specific cylinder in either compression or expansion stroke, ensuring that the same cylinder is brought into the compression stroke at startup, thereby canceling out the precession-induced vibration components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the engine is stopped without controlling the cylinder position, then the control complexity is reduced, but the vibration at startup increases due to precession
Solution Approach 1:
The control apparatus determines the crank angle position before stopping the engine and adjusts the stopping timing in advance to ensure a specific cylinder is in the compression stroke. This preliminary positioning prevents precession-induced vibrations during subsequent startup without requiring complex real-time adjustments.
Solution Approach 2:
The invention changes the parameter of crank angle position at which the engine is stopped. By controlling the engine to stop when a specific cylinder is in the compression stroke (specific crank angle range), the vibration characteristics are optimized to reduce startup vibrations while maintaining simple control logic.
2Object-affected harmful factors
If the engine is stopped with a specific cylinder in compression stroke, then the startup vibration is reduced, but the control precision requirement increases
Solution Approach 1:
Instead of requiring precise control of the crank angle to a narrow range, the invention uses a broader specified crank angle range that ensures the specific cylinder is in the compression stroke. This partial precision approach achieves vibration reduction without demanding excessively high measurement and control precision.
3Adaptability or versatility
If the engine stop position is randomized, then the system adaptability is improved, but the vibration magnitude increases due to precession phase variation
Solution Approach 1:
The invention creates a homogeneous stopping condition where the engine always stops with the same specific cylinder in the compression stroke. This consistency in stopping position ensures that the precession phase remains constant, allowing the vibration components to cancel each other out effectively and reducing overall vibration magnitude.
Data Source
AI summary
A control apparatus of the invention is applied to a three-cylinder internal combustion engine that is mounted in a vehicle and in which a first MG is connected to a crankshaft in a manner capable of transmitting power. When stopping the internal combustion engine, a vehicle control unit controls output torque of the first MG such that the internal combustion engine is stopped in a state where a preset particular cylinder is in a compression stroke. The particular cylinder is a cylinder in which a mutually weakening relationship is established between a vibration component that is generated due to precession in the internal combustion engine when the internal combustion engine is started from the state where this particular cylinder is in the compression stroke and a vibration component that is predicted to be generated in the vehicle when it is assumed that torque to be applied to the crankshaft at a startup of the internal combustion engine is applied to the crankshaft in a state where a piston and a connecting rod of each cylinder are detached.