SPCCI Engine Torque Control via Fuel Reduction
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Solution Overview
Problem
The challenge is to execute vehicle attitude control in an engine capable of SPCCI combustion without affecting the combustion performance, as ignition retardation during SPCCI combustion can lead to misfires due to insufficient in-cylinder pressure for CI combustion.
Innovation Solution
A control method that selects between SI and SPCCI combustion modes based on the steering angle, using ignition timing retardation and fuel injection reduction to adjust torque output, ensuring sufficient in-cylinder temperature and pressure for SPCCI combustion without misfires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If ignition timing is retarded to reduce engine output torque for vehicle attitude control, then vehicle attitude control is achieved, but in-cylinder pressure becomes insufficient for CI combustion causing misfire
Solution Approach 1:
The system dynamically switches between two torque reduction strategies based on combustion mode: for SI combustion, ignition timing is retarded to reduce torque; for SPCCI combustion, fuel injection amount is reduced instead. This dynamic adaptation allows the system to maintain combustion stability while achieving vehicle attitude control in SPCCI mode by preserving the ignition timing necessary for sufficient in-cylinder pressure generation.
Solution Approach 2:
The control system changes the controlled parameter based on combustion mode: in SI mode, ignition timing is adjusted; in SPCCI mode, fuel injection amount is adjusted. This parameter switching enables torque reduction for vehicle attitude control in SI mode while maintaining ignition timing for adequate in-cylinder pressure in SPCCI mode, thus preventing misfire.
2Power
If fuel injection amount is reduced to decrease engine output torque, then torque reduction for vehicle attitude control is achieved, but combustion performance and power output are compromised
Solution Approach 1:
The system dynamically selects the appropriate torque control strategy based on combustion mode. In SPCCI mode, when combustion efficiency is prioritized, the system uses fuel injection amount reduction rather than ignition timing retardation, thereby maintaining combustion performance while still achieving the required torque reduction for vehicle attitude control.
3Power
If ignition timing is retarded during SPCCI combustion, then torque is reduced for vehicle attitude control, but the late phase CI combustion cannot be sustained due to insufficient pressure
Solution Approach 1:
The control system changes the controlled parameter based on combustion mode: in SI mode, ignition timing is adjusted; in SPCCI mode, fuel injection amount is adjusted. This parameter switching enables torque reduction for vehicle attitude control in SI mode while maintaining ignition timing for adequate in-cylinder pressure in SPCCI mode, thus preventing misfire.
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 allows for effective vehicle attitude control without compromising SPCCI combustion performance, preventing misfires by maintaining adequate in-cylinder conditions during SPCCI combustion.
Implementation Method 1
a part of an air-fuel mixture is forcibly combusted by flame propagation triggered by spark ignition (SI combustion)
Implementation Method 2
the remaining unburned air-fuel mixture is combusted by self-ignition (CI combustion)
Implementation Method 3
controlling the fuel injector based on the torque reduction amount set in the decremental torque setting step so as to reduce a fuel injection amount
Data Source
AI summary
When an incremental amount of a steering angle exceeds a reference incremental amount, an ECU 60 executes vehicle attitude control of reducing an output torque of an engine, and, in a given operating range, drives a spark plug 16 in a manner allowing an air-fuel mixture to be self-ignited at a given timing, thereby executing SPCCI combustion. When there is a request for an additional deceleration from the vehicle attitude control (#12: YES), and the SPCCI combustion is performed (#13: YES), the ECU 60 executes fuel amount reduction control of reducing the amount of fuel to be supplied into a cylinder 2 (#14), so as to attain torque reduction for the vehicle attitude control. On the other hand, when the SPCCI combustion is not performed (#13: NO), the ECU 60 executes ignition retardation control of retarding an ignition timing of the spark plug 16 (#15).