Fuel injection amount control apparatus for internal combustion engine, control system for power unit, and fuel injection amount control method for internal combustion engine

A control system for a power unit that includes an internal combustion engine, and an power transmission apparatus that has a torque converter that transmits power from the internal combustion engine, and a lockup mechanism that locks up the torque converter,

• the control system comprising:
• a fuel injection amount control apparatus which generates an injection command signal that commands an injector of the internal combustion engine to inject fuel, and which learns change in fuel injection performance of the injector under a pre-set learning condition, and which corrects the injection command signal according to a result of learning;
• and
• a lockup control apparatus that controls operation of the lockup mechanism of the automatic transmission,
• wherein
• the fuel injection amount control apparatus includes:
• a rotation speed detection portion that detects engine rotation speed of the internal combustion engine;
• a first determination portion that determines whether or not a first learning condition regarding operation state of the internal combustion engine is satisfied;
• a second determination portion that determines whether or not a second learning condition regarding operation state of the lockup mechanism is satisfied;
• a learning-purpose injection command portion that commands the injector to perform a learning-purpose injection with a pre-set commanded injection amount when it is determined that both the first learning condition and the second learning condition are satisfied;
• a performance value calculation portion that calculates an amount of change in the engine rotation speed of the internal combustion engine caused by the learning-purpose injection based on detected information from the rotation speed detection portion, when the learning-purpose injection is performed by the injector according to the command from the learning-purpose injection command portion, and calculating an injection performance value that corresponds to an actual injection amount of the injector based on the amount of change;
• a correction portion that corrects the injection command signal according to a difference between the actual injection amount of the injector that is specifically determined from the injection performance value and the commanded injection amount that is commanded to the injector;
• a third determination portion that determines whether or not a delay equal to or longer than a certain length of time which occurs in the learning process is permitted, based on whether or not the learning process, despite occurrence of the delay of the learning process, is able to be completed before the fuel injection performance of the injector reaches a pre-set permissible limit value;
• and
• a compulsive signal output portion that outputs to the lockup control apparatus a compulsive signal that forces a completely locked-up state of the lockup mechanism to be prohibited so as to satisfy the second learning condition, when it is determined by the first determination portion that the first learning condition is satisfied and it is determined by the second determination portion that the second learning condition is not satisfied while it is determined by the third determination portion that the delay of the learning process is not permitted,
• and wherein
• when the lockup control apparatus inputs the compulsive signal, the lockup control apparatus restricts action of the lockup mechanism within a range in which the lockup mechanism does not assume the completely locked-up state, and when it is determined by the third determination portion that the delay of the learning process is permitted, the control system permits the delay of the learning process until it is determined that both the first learning condition and the second learning condition are satisfied.

A fuel injection amount control method for an internal combustion engine which generates an injection command signal that commands an injector of the internal combustion engine to inject fuel, and executes a learning process of learning change in fuel injection performance of the injector under a pre-set learning condition, and corrects the injection command signal according to a result of the learning process, comprising:

• detecting engine rotation speed of the internal combustion engine;
• determining whether or not a first learning condition regarding operation state of the internal combustion engine is satisfied;
• determining whether or not a second learning condition regarding load connection state of the internal combustion engine is satisfied;
• commanding the injector to perform a learning-purpose injection with a pre-set commanded injection amount when it is determined that both the first learning condition and the second learning condition are satisfied;
• calculating an amount of change in the engine rotation speed of the internal combustion engine caused by the learning-purpose injection based on the engine rotation speed detected, when the learning-purpose injection is performed by the injector, and calculating an injection performance value that corresponds to an actual injection amount of the injector based on the amount of change;
• correcting the injection command signal according to a difference between the actual injection amount of the injector that is specifically determined from the injection performance value and the commanded injection amount that is commanded to the injector;
• determining whether or not a delay equal to or longer than a certain length of time which occurs in the learning process is permitted, based on whether or not the learning process, despite occurrence of the delay of the learning process, is able to be completed before the fuel injection performance of the injector reaches a pre-set permissible limit value;
• and
• outputting a compulsive signal that forces the load connection state of the internal combustion engine to be a specific connection state so as to satisfy the second learning condition, when it is determined that the delay of the learning process is not permitted, wherein
• when it is determined that the delay of the learning process is permitted, the delay of the learning process is permitted until it is determined that both the first learning condition and the second learning condition are satisfied.