Engine Starting Control via Cylinder Pressure Monitoring
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Solution Overview
Problem
Existing engine starting control systems face challenges in determining whether autonomous starting can be performed successfully before switching to starter motor assistance, leading to potential slowness in engine restart due to variations in crankshaft kinetic energy and cylinder pressure during the restarting process.
Innovation Solution
A starting control device with an ECU that monitors cylinder pressure and crankshaft conditions to determine if the pressure is sufficient for autonomous starting, injecting fuel and igniting the air-fuel mixture only when the pressure meets a predetermined threshold, and switching to starter motor assistance if not.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fuel injection and ignition are performed when the piston returns to a predetermined position in the vicinity of the top dead center, then autonomous starting is attempted, but the crankshaft may rotate forward again before ignition and autonomous starting may fail
Solution Approach 1:
The ECU performs preliminary determination of cylinder pressure before initiating fuel injection and ignition. By checking whether the cylinder pressure is equal to or greater than a predetermined pressure at the time point of firing, the system ensures that autonomous starting conditions are met before attempting combustion, preventing starting failure due to premature ignition.
2Reliability
If autonomous starting is attempted without sufficient cylinder pressure, then starting may fail, but switching to starter motor after rotation stops causes perceived slowness
Solution Approach 1:
The ECU continuously monitors cylinder pressure and provides feedback to determine whether autonomous starting should be performed. By determining whether the cylinder pressure meets the predetermined threshold at the time point of firing, the system makes real-time decisions to either proceed with autonomous starting or switch to starter motor assistance, optimizing both reliability and response time.
3Adaptability or versatility
If the piston does not return to the predetermined position due to variation in crankshaft kinetic energy, then cylinder pressure is insufficient and combustion torque decreases
Solution Approach 1:
The system changes the decision parameter from piston position to cylinder pressure. Instead of determining autonomous starting feasibility based on piston position in the vicinity of top dead center, the ECU determines feasibility based on whether cylinder pressure is equal to or greater than a predetermined pressure at the time point of firing. This parameter change allows the system to adapt to variations in crankshaft kinetic energy and intake air amount, ensuring reliable autonomous starting decisions under varying operating conditions.
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
Ensures rapid and smooth engine restart by accurately determining the feasibility of autonomous starting and preventing driver-perceived slowness by ensuring the cylinder pressure is adequate for successful ignition.
Implementation Method 1
ignites an air-fuel mixture using an ignition plug
Implementation Method 2
ignites an air-fuel mixture using an ignition plug to start the engine
Implementation Method 3
injects fuel into the expansion stroke cylinder from a fuel injection valve
Data Source
AI summary
A starting control device for an engine includes an ECU configured to: i) execute an autonomous starting control in which the ECU injects fuel into the cylinder from a fuel injection valve after a crank shaft rotates reversely before the crank shaft stops its rotation and then ignites an air-fuel mixture using an ignition plug to start the engine without using a starter motor; ii) determine whether a pressure in the cylinder increasing due to the reverse rotation is equal to or greater than a predetermined pressure at a time point of firing of the air-fuel mixture by the ignition; and iii) prohibit starting of the engine under the autonomous starting control when the ECU determines that the pressure in the cylinder is not equal to or greater than the predetermined pressure.