초록 ▼

A system and method for transient torque control of a direct injection spark ignition engine include controlling airflow and fuel flow rather than ignition timing so that spark timing may be set for best fuel economy. The system and method are particularly suited for variable cam timing or variable

A system and method for transient torque control of a direct injection spark ignition engine include controlling airflow and fuel flow rather than ignition timing so that spark timing may be set for best fuel economy. The system and method are particularly suited for variable cam timing or variable valve timing DISI engines where valve timing enables a sufficiently fast engine torque response to achieve transient control. The present invention may be used for torque-based speed control strategies, such as idle speed control or cruise control. The invention includes determining a maximum available airflow to determine whether a desired torque and air/fuel ratio can be achieved using airflow. Otherwise, the invention uses fuel flow control based on the maximum available air flow to provide the desired engine output torque and air/fuel ratio.

대표청구항 ▼

[ What is claimed is:] [1.]1. A method for transient torque control on a direct injection spark ignition internal combustion engine, the method comprising:determining a desired value for engine torque based on current engine operating conditions;determining a desired value for cylinder air/fuel rati

[ What is claimed is:] [1.]1. A method for transient torque control on a direct injection spark ignition internal combustion engine, the method comprising:determining a desired value for engine torque based on current engine operating conditions;determining a desired value for cylinder air/fuel ratio based on current engine operating conditions;determining an air flow upper bound for currently available cylinder air flow based on current engine operating conditions;determining desired fuel flow and air flow values with minimum deviation from MBT spark timing to obtain the desired engine torque and air/fuel ratio values; andcontrolling at least one fuel flow actuator and at least one air flow without altering spark timing to deliver the desired cylinder fuel flow and the desired cylinder air flow if the desired cylinder air flow is less than the upper bound, and setting the desired cylinder air flow to the upper bound if the desired cylinder airflow exceeds the upper bound.