| CPC F02D 41/0052 (2013.01) [F02D 41/0047 (2013.01); F02D 2200/023 (2013.01); F02D 2200/0611 (2013.01)] | 4 Claims |
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1. An engine control device applicable to an engine of a spark ignition type, the engine being equipped with an ignition device, which is configured to perform ignition in a cylinder, and an EGR device, which is configured to recirculate exhaust gas to an air intake passage, the engine being configured to use a mixed fuel containing different types of fuel mixed with gasoline, the engine control device configured to, on a premise that gasoline is used, control an in-cylinder temperature immediately before combustion and control an EGR rate of the EGR device, the engine control device comprising:
an index calculation unit configured to calculate, as indices relating to a fuel property, a first index, which indicates a degree of anti-knocking margin, and a second index, which indicates a required ignition energy required for normal ignition;
a first determination unit configured to determine that the degree of anti-knocking margin, as the first index, deviates from a degree of anti-knocking margin in a case where gasoline is used;
a second determination unit configured to determine that the required ignition energy, as the second index, deviates from a required ignition energy in a case where gasoline is used;
a first control unit configured to
set a target in-cylinder temperature based on the first index and
control the in-cylinder temperature based on the target in-cylinder temperature to perform an in-cylinder temperature control to control the in-cylinder temperature immediately before combustion; and
a second control unit configured to
set a target EGR rate based on the second index and
control the EGR rate based on the target EGR rate to perform an EGR control to control the EGR rate of the EGR device, wherein
the engine control device is configured to, based on a determination result of the first determination unit and a determination result of the second determination unit, selectively
perform the in-cylinder temperature control to increase the target in-cylinder temperature to more than a target in-cylinder temperature in a case where gasoline is used and
perform the EGR control to increase the target EGR rate to more than a target EGR rate in a case where gasoline is used, and
the engine control device is configured to, when the first determination unit determines that the degree of anti-knocking margin is greater than the degree of anti-knocking margin in a case where gasoline is used, and when the second determination unit determines that the required ignition energy is not smaller than the required ignition energy in a case where gasoline is used,
determine whether the EGR control, which is to set the target EGR rate higher than the target EGR rate in a case where gasoline is used, is performable based on an EGR limit, which is an upper limit value of the EGR rate determined according to the required ignition energy, and an EGR limit extended amount, which determined according to the degree of the anti-knocking margin.
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