CONTROL DEVICE, EXHAUST GAS PURIFICATION SYSTEM, AND CONTROL METHOD OF ENGINE

Provided is a control device configured to be able to execute a forced regeneration process in an engine which includes a DOC and DPF disposed in an exhaust passage of the engine, and a temperature increase unit including an exhaust throttle valve, for increasing a temperature of each of the DOC and the DPF. The forced regeneration process includes a first temperature increase process of controlling the temperature increase unit such that the temperature of the DOC is increased to a first temperature, and a second temperature increase process of controlling the temperature increase unit such that the temperature of the DPF is increased to a second temperature which is higher than the first temperature after completion of the first temperature increase process. The control device includes a valve opening/closing operation execution part configured to cause the exhaust throttle valve to execute a valve opening/closing operation of increasing an opening degree of the exhaust throttle valve to be greater than a predetermined opening degree for a predetermined time, when the forced regeneration process is switched from the first temperature increase process to the second temperature increase process.