Vehicle Control Device for Ignition Start Torque Optimization
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Solution Overview
Problem
The ignition start in a cylinder stopped in the expansion stroke may not generate sufficient explosion torque to overcome the engine's friction torque, leading to decreased engine startability due to reduced oxygen concentration caused by exhaust valve opening, resulting in misfires or low torque generation.
Innovation Solution
A control device that switches the cylinder for initial combustion based on exhaust valve actuation during engine rotation stop, using reversal starts and fuel injection during negative rotation to enhance oxygen homogenization and compression, ensuring high explosion torque generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If fuel is injected and ignited in a cylinder stopped in the expansion stroke to perform ignition start, then the engine rotation speed can be increased by explosion torque, but the oxygen concentration in the cylinder is reduced due to exhaust valve opening and backward flow of exhaust gas, leading to insufficient explosion torque and decreased engine startability
Solution Approach 1:
The control device temporarily opens the exhaust valve before causing combustion in the expansion stroke cylinder. This preliminary action allows fresh air to enter the cylinder and replace the low-oxygen exhaust gas, ensuring sufficient oxygen concentration is available when fuel injection and ignition occur, thereby enabling generation of high explosion torque for successful engine start
Solution Approach 2:
Instead of directly igniting fuel in the expansion stroke cylinder with reduced oxygen concentration, the control device inverts the sequence by first temporarily opening the exhaust valve to refresh the air-fuel mixture, then causing combustion. This inverted approach transforms the harmful low-oxygen condition into a favorable high-oxygen condition for combustion
2Power
If the exhaust valve is temporarily opened to increase oxygen concentration, then high explosion torque can be generated, but the engine rotation speed may increase excessively causing overshoot beyond electric motor rotation speed, delaying clutch engagement
Solution Approach 1:
The control device uses feedback control to monitor engine rotation speed and adjust the combustion timing and intensity accordingly. By detecting the actual rotation speed and comparing it with the target speed, the control device can modulate the fuel injection amount and ignition timing to achieve the desired rotation speed increase without excessive overshoot, ensuring timely clutch engagement
Solution Approach 2:
The control device changes combustion parameters such as fuel injection amount, injection timing, and ignition timing based on the temporarily opened exhaust valve condition. By adjusting these parameters, the explosion torque is optimized to produce controlled engine rotation speed increase that avoids excessive overshoot while still achieving successful engine start
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
Improves engine startability by generating high explosion torque even with reduced oxygen concentration, suppressing overshoot and facilitating complete clutch engagement, thereby enhancing engine rotation speed and drivability.
Implementation Method 1
opening of an exhaust valve of the cylinder in the expansion stroke reduces the oxygen concentration in the cylinder due to a backward flow of exhaust gas
Implementation Method 2
performing an ignition start causing combustion in a cylinder of the engine to rotate the engine at a start of the engine
Implementation Method 3
putting the cylinder into a state in which a high explosion torque is generated before causing the combustion in the cylinder
Data Source
AI summary
A control device of a vehicle including an engine, an electric motor, and a clutch disposed on a power transmission path between the engine and the electric motor, the control device of a vehicle performing an ignition start causing combustion in a cylinder of the engine to rotate the engine at a start of the engine, the control device of a vehicle switching a cylinder in which combustion is first caused in the engine based on an actuation during a rotation stop process of the engine of an exhaust valve in a cylinder stopped in an expansion stroke, when performing the ignition start at the start of the engine.