Method and structure for controlling an apparatus, such as a fuel injector, using electronic trimming

A method of operating a plurality of electronically-controlled fuel injectors of the type having a nominal start of injection characteristic wherein fuel injection is controlled by a fuel delivery signal, comprising the steps of:

• measuring, for each injector, a respective start of injection characteristic;
• associating, for each injector, the measured start of injection characteristic with the respective injector;
• adjusting, for each injector, the fuel delivery signal as a function of the variation of the respectively associated measured start of injection characteristic from the nominal start of injection characteristic;
• controlling each injector in accordance with the respective adjusted fuel delivery signal to reduce start of injection variation.

A method of operating a plurality of electronically-controlled fuel injectors wherein fuel injection is controlled by a fuel delivery signal, the injectors being of the type having a nominal delivery characteristic as a function of operating conditions, comprising the steps of:

• measuring, for each injector, a respective delivery characteristic at a plurality of operating conditions;
• associating, for each injector, the measured delivery characteristic with the respective injector;
• adjusting for each injector, the fuel delivery signal as a function of the variation of the respectively associated measured delivery characteristic from the nominal delivery characteristic at each operating condition of the injector;
• controlling each injector in accordance with the respective adjusted fuel delivery signal to minimize injector to injector delivery variation.

A method of operating a plurality of electronically-controlled fuel injectors wherein fuel injection is controlled by a fuel delivery signal generated by a control means having a memory means, the injectors being of the type having a nominal start of injection characteristic and nominal delivery characteristic, comprising the steps of:

• measuring, for each injector, a respective start of injection characteristic and delivery characteristic;
• categorizing each injector into one of a plurality of trim categories as a function of the variation of the measured start of injection and delivery characteristics from the respective nominal start of injection and delivery characteristics, each trim category having an associated start of injection and delivery offset value;
• recording the category into which each injector was categorized in said categorizing step on a respective injector;
• storing the respective category recorded on each injector in the memory means;
• calculating the fuel delivery signal as a function of actual operating conditions based on nominal start of injection and delivery characteristics;
• adjusting the fuel delivery signal for each injector as a function of the respective start of injection and delivery offset values;
• controlling each injector in accordance with the respective adjusted fuel delivery signal to reduce start of injection and delivery variation.

A system for controlling the delivery of fuel through a plurality of fuel injectors to an engine, each injector being of the type characterized by at least one observed performance parameter, comprising:

• sensor means for detecting a plurality of operating parameters and generating a respective plurality of operating parameter signals indicative of the parameter detected;
• control means responsive to said operating parameter signals for generating a base fuel delivery signal for each injector;
• each fuel injector being coupled with said control means to receive a respective base fuel delivery signal for controlled fuel delivery to the engine;
• memory means coupled with said control means for storing trim signals for each injector, said trim signals being derived from observed performance parameter values taken at a plurality of operating conditions;
• means for communicating said trim signals to said memory means;
• said control means being responsive to said trim signals for trimming said base fuel delivery signal for each injector as a function of said trim signals and as a function of said operating parameter signals for reducing performance parameter variation.