Method of implementing control logic of compression-ignition engine

A method of implementing control logic of a compression-ignition engine, the engine comprising:

• a injector configured to inject fuel to be supplied in a combustion chamber;
• a variable valve operating mechanism configured to change a valve timing of an intake valve;
• an ignition plug configured to ignite a mixture gas inside the combustion chamber;
• at least one sensor configured to measure a parameter related to an operating state of the engine;
• and a controller including a processor configured to execute the control logic and a memory in which the control logic is stored, the controller being configured to perform a calculation according to the control logic corresponding to the operating state of the engine in response to the measurement of the at least one sensor, and output a signal to the injector, the variable valve operating mechanism, and the ignition plug, the controller outputting the signal to the injector and the variable valve operating mechanism so that a gas-fuel ratio (G/F) that is a weight ratio of an entire gas of the mixture gas inside the combustion chamber to the fuel becomes leaner than a stoichiometric air fuel ratio, and an air-fuel ratio (A/F) that is a weight ratio of air contained in the mixture gas to the fuel becomes the stoichiometric air fuel ratio or richer than the stoichiometric air fuel ratio, and outputting a signal to the ignition plug so that unburnt mixture gas combusts by self-ignition after the ignition plug ignites the mixture gas inside the combustion chamber, and the method comprising:
• determining a geometric compression ratio ε of the engine;
• executing, by the processor, the control logic defining a valve close timing IVC of the intake valve;
• and
• closing, by the variable valve operating mechanism, the intake valve when the valve close timing IVC (deg.aBDC) is determined so that the following expression is satisfied:
• if the fuel is a low octane fuel, and
• if the geometric compression ratio ε is 10≤ε<15.7,
• 0.4234ε2−21.826ε+178.75+C≤IVC≤−0.4234ε2+321.826ε−138.75+C
• and if the geometric compression ratio ε is 15.7≤ε<18.7,
• −0.5603ε2+34.859ε−377.22+C≤IVC≤−0.4234ε2+21.826ε−138.75+C
• or
• 0.4234ε2−32.826ε+178.75+C≤IVC≤1.9211ε2−85.076ε+862.01+C
• and if the geometric compression ratio ε is 18.7≤ε≤30,
• −0.5603ε2+34.859ε−377.22+C≤IVC≤120
• or
• −80≤IVC≤1.9211ε2−85.076ε+862.01+C
• where C is the correction term according to an engine speed NE (rpm),
• C=3.3×10−10NE3−1.0×10−6NE2+7.0×10−4NE.

A method of implementing control logic of a compression-ignition engine, the engine comprising:

• a injector configured to inject fuel to be supplied in a combustion chamber;
• a variable valve operating mechanism configured to change a valve timing of an intake valve;
• an ignition plug configured to ignite a mixture gas inside the combustion chamber;
• at least one sensor configured to measure a parameter related to an operating state of the engine;
• and a controller including a processor configured to execute the control logic and a memory in which the control logic is stored, the controller being configured to perform a calculation according to the control logic corresponding to the operating state of the engine in response to the measurement of the at least one sensor, and output a signal to the injector, the variable valve operating mechanism, and the ignition plug, the controller outputting the signal to the injector and the variable valve operating mechanism so that an air-fuel ratio (A/F) that is a weight ratio of air contained in the mixture gas to the fuel becomes leaner than the stoichiometric air fuel ratio, and outputting a signal to the ignition plug so that unburnt mixture gas combusts by self-ignition after the ignition plug ignites the mixture gas inside the combustion chamber, and the method comprising:
• determining a geometric compression ratio ε of the engine;
• executing, by the processor, the control logic defining a valve close timing IVC of the intake valve;
• and
• closing, by the variable valve operating mechanism, the intake valve when the valve close timing IVC (deg.aBDC) is determined so that the following expression is satisfied:
• if the geometric compression ratio ε is 10≤ε<20,
• 0.9949ε2−41.736ε+401.16+C≤IVC≤−0.9949ε2+41.736ε−361.16+C
• and if the geometric compression ratio ε is 20≤ε<25,
• −35+C≤IVC≤75+C
• and if the geometric compression ratio ε 25≤ε≤30,
• −4.7481ε2+266.75ε2−3671.2+C≤IVC≤75+C
• or
• −35+C≤IVC≤4.47581ε2−266.75ε+3711.2+C
• where C is a correction term according to an engine speed NE (rpm),
• C=3.3×10−10NE3−1.0×10−6NE2+7.0×10−4NE.

A method of implementing control logic of a compression-ignition engine, the engine comprising:

• a injector configured to inject fuel to be supplied in a combustion chamber;
• a variable valve operating mechanism configured to change a valve timing of an intake valve;
• an ignition plug configured to ignite a mixture gas inside the combustion chamber;
• at least one sensor configured to measure a parameter related to an operating state of the engine;
• and a controller including a processor configured to execute the control logic and a memory in which the control logic is stored, the controller being configured to perform a calculation according to the control logic corresponding to the operating state of the engine in response to the measurement of the at least one sensor, and output a signal to the injector, the variable valve operating mechanism, and the ignition plug, the controller outputting the signal to the injector and the variable valve operating mechanism so that an air-fuel ratio (A/F) that is a weight ratio of air contained in the mixture gas to the fuel becomes leaner than a stoichiometric air fuel ratio, and outputting a signal to the ignition plug so that unburnt mixture gas combusts by self-ignition after the ignition plug ignites the mixture gas inside the combustion chamber, and the method comprising:
• determining a geometric compression ratio ε of the engine;
• executing, by the processor, the control logic defining a valve close timing IVC of the intake valve;
• and
• closing, by the variable valve operating mechanism, the intake valve when the valve close timing IVC (deg.aBDC) is determined so that the following expression is satisfied:
• if the fuel is a low octane fuel, and
• if the geometric compression ratio ε is 10≤ε<18.7,
• 0.9949ε2−39.149ε+348.59+C≤IVC≤−0.9949ε2+39.149ε−308.59+C
• and if the geometric compression ratio ε is 18.7≤ε<23.7,
• −35+C≤IVC≤75+C
• and if the geometric compression ratio ε is 23.7≤ε≤30,
• −3.1298ε2+172.48ε−2300+C≤IVC≤75+C
• or
• −35+C≤IVC≤3.1298ε2−172.48ε+2340+C
• where C is the correction term according to an engine speed NE (rpm),
• C=3.3×10−10NE3−1.0×10−6NE2+7.0×10−4NE.