Diesel engine

A diesel engine comprising:

• a fuel injection device configured to inject fuel into a combustion chamber;
• an exhaust-air throttle valve disposed in an exhaust-air path;
• a valve downstream-side DOC disposed on an exhaust downstream side of the exhaust-air throttle valve;
• a DPF disposed on an exhaust downstream side of the valve downstream-side DOC;
• and
• an electronic control device configured to control an opening degree of the exhaust-air throttle valve and fuel injection of the fuel injection device,
• wherein a regeneration process of the DPF and a regeneration process of the valve downstream-side DOC are performed,
• wherein, in the regeneration process of the DPF, post-injection control is started after a start condition of the regeneration process of the DPF in which PM is deposited is satisfied, and the PM deposited in the DPF is incinerated by exhaust air increased in temperature by catalytic combustion of post-injection fuel in the valve downstream-side DOC, and
• wherein, in a catalyst function recovery process of the valve downstream-side DOC, opening-degree reduction control for the exhaust-air throttle valve is performed after a start condition of the catalyst function recovery process of the valve downstream-side DOC whose function has deteriorated based on deposition of an unburned deposit of unburned fuel or the PM is satisfied, after-injection control is started after the exhaust air reaches a temperature equal to or higher than a predetermined after-injection permissible temperature, and the unburned deposit deposited in the valve downstream-side DOC is vaporized or incinerated by the exhaust air increased in temperature by combustion of after-injection fuel.

A diesel engine comprising:

• a fuel injection device configured to inject fuel into a combustion chamber;
• an exhaust-air throttle valve disposed in an exhaust-air path;
• a valve upstream-side DOC disposed on an exhaust upstream side of the exhaust-air throttle valve;
• a DPF disposed on an exhaust downstream side of the exhaust-air throttle valve;
• and
• an electronic control device configured to control an opening degree of the exhaust-air throttle valve and fuel injection of the fuel injection device,
• wherein a regeneration process of the DPF and a catalyst function recovery process of the valve upstream-side DOC are performed,
• wherein, in the regeneration process of the DPF, post-injection control is started after a start condition of the regeneration process of the DPF in which PM is deposited is satisfied, post-injection fuel is catalytically burned in the valve upstream-side DOC, and the PM deposited in the DPF is incinerated by heat of exhaust air increased in temperature, and
• wherein, in the catalyst function recovery process of the valve upstream-side DOC, opening-degree reduction control for the exhaust-air throttle valve is performed after a start condition of the catalyst function recovery process of the valve upstream-side DOC whose function has deteriorated based on deposition of an unburned deposit of unburned fuel or the PM is satisfied, after-injection control is started after the exhaust air reaches a temperature equal to or higher than a predetermined after-injection permissible temperature, post-injection control is started after the exhaust air reaches a temperature equal to or higher than a predetermined post-injection fuel permissible temperature by combustion of after injection fuel, the post-injection fuel is burned by combustion heat of the after-injection fuel, and the unburned deposit deposited in the valve upstream-side DOC is vaporized or incinerated by heat of the exhaust air increased in temperature.