Exhaust Purification Device of Engine, Vehicle Engine Including Exhaust Purification Device, and Method of Controlling Engine

A vehicle engine capable of purifying an exhaust gas and mounted on a vehicle, the vehicle engine comprising:

• an engine body;
• a fuel injection valve which supplies fuel into the engine body;
• an intake passage through which air introduced into the engine body flows;
• an exhaust passage through which an exhaust gas discharged from the engine body flows;
• an EGR passage which makes the intake passage and the exhaust passage communicate with each other;
• a throttle valve disposed openably and closably in the intake passage;
• an EGR valve disposed openably and closably in the EGR passage;
• an oxidation catalyst which is disposed in the exhaust passage and purifies HC and CO contained in the exhaust gas;
• a urea injector which is disposed in the exhaust passage downstream of the oxidation catalyst and supplies urea into the exhaust passage;
• an SCR catalyst which is disposed in the exhaust passage downstream of the urea injector and purifies NOx in the exhaust gas by a reduction action of ammonium produced from the urea;
• and
• a controller which controls the fuel injection valve, the throttle valve, the EGR valve, and the urea injector,
• wherein the controller is configured to perform deceleration fuel cut for stopping supply of the fuel by the fuel injection valve during deceleration in which an opening degree of an accelerator pedal of a vehicle is set to zero,
• the controller is configured to perform a first flow regulating control in which an opening degree of the throttle valve is lowered compared to the opening degree of the throttle valve immediately before starting of the deceleration fuel cut in a case where a first temperature condition that the oxidation catalyst is in a low temperature state at the time of performing the deceleration fuel cut is established, and
• the controller is configured to perform a second flow regulating control in which an opening degree of the EGR valve is lowered compared to the opening degree of the EGR valve immediately before starting of the deceleration fuel cut in a case where a second temperature condition that the oxidation catalyst is in a temperature state higher than the low temperature state and the SCR catalyst is in a low temperature state at the time of performing the deceleration fuel cut is established.

A method for controlling an engine which includes:

• an engine body;
• a fuel injection valve which supplies fuel into the engine body;
• an exhaust passage through which an exhaust gas discharged from the engine body flows;
• an oxidation catalyst which is disposed in the exhaust passage and purifies HC and CO contained in the exhaust gas;
• a urea injector which is disposed in the exhaust passage downstream of the oxidation catalyst and supplies urea into the exhaust passage;
• an SCR catalyst which is disposed in the exhaust passage downstream of the urea injector and purifies NOx in the exhaust gas by a reduction action of ammonium produced from the urea;
• and
• a control valve capable of regulating a flow rate of the exhaust gas which flows through the exhaust passage, the method comprising the steps of:
• performing deceleration fuel cut for stopping supply of the fuel by the fuel injection valve during deceleration;
• controlling the control valve so as to decrease a flow rate of the exhaust gas which passes through the oxidation catalyst and the SCR catalyst in a case where a first temperature condition that the oxidation catalyst is in a low temperature state at the time of performing the deceleration fuel cut is established;
• and
• controlling the control valve so as to increase the flow rate of the exhaust gas which passes through the oxidation catalyst and the SCR catalyst, compared to the case where the first temperature condition is established, in a case where a second temperature condition that the oxidation catalyst is in a temperature state higher than the low temperature state and the SCR catalyst is in a low temperature state at the time of performing the deceleration fuel cut is established.