Control device for internal combustion engine

A control device for an internal combustion engine,

• the internal combustion engine including an EGR device that includes:
• an EGR passage configured to connect an intake air passage of the internal combustion engine with an exhaust gas passage thereof;
• an EGR cooler arranged at the EGR passage;
• an EGR cooler bypass passage through which, when at least a part of EGR gas flowing through the EGR passage bypasses the EGR cooler, the at least a part of EGR gas flows;
• and
• a flow-rate-ratio control valve equipped with a valve disc and capable of controlling, by adjustment of an opening degree of the valve disc, a flow rate ratio of a flow rate of a cooler passing-through gas that is an EGR gas flowing through the EGR cooler and a flow rate of a bypass passing-through gas that is an EGR gas flowing through the EGR cooler bypass passage,
• wherein the control device is configured, when an opening degree control execution condition is met, to execute a vibration reduction control for controlling the flow-rate-ratio control valve such that the opening degree of the valve disc becomes greater than or equal to a vibration reduction opening degree that is greater than a minimum opening degree within an opening degree control range of the valve disc, and
• wherein the opening degree control execution condition includes a requirement that a parameter that becomes greater when exhaust pulsation acting on the valve disc is greater is equal to or greater than a first threshold value.