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

Patent metadata

Field	Value
Publication number	US-2019093529-A1
Application number	US-201816108699-A
Country	US
Kind code	A1
Filing date	Aug 22, 2018
Priority date	Sep 22, 2017
Publication date	Mar 28, 2019
Grant date	—

Abstract

In an engine which includes an oxidation catalyst and an SCR catalyst in an exhaust passage, a first flow regulating control in which a control valve is controlled so as to decrease a flow rate of an exhaust gas which passes through the oxidation catalyst and the SCR catalyst is performed in a case where the oxidation catalyst is in a low temperature state at the time of performing deceleration fuel cut, and a second flow regulating control in which the control valve is controlled so as to increase the flow rate of the exhaust gas which passes through the oxidation catalyst and the SCR catalyst is performed in a case where 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.

First claim

1 . An exhaust purification device of an engine comprising:
an exhaust passage through which an exhaust gas discharged from an 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; a control valve capable of regulating a flow rate of the exhaust gas which flows through the exhaust passage; and a controller which controls the urea injector and the control valve, wherein the controller is configured to perform a first flow regulating control in which the control valve is controlled so as to decrease the 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 deceleration fuel cut for stopping supply of fuel into the engine body during deceleration is established, and the controller is configured to perform a second flow regulating control in which the control valve is controlled so as to increase the flow rate of the exhaust gas which passes through the oxidation catalyst and the SCR catalyst compared to the first flow regulating control 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.

2 . The exhaust purification device of an engine according to claim 1 , wherein
the controller is configured to perform a normal control which includes no flow rate regulation of the exhaust gas in response to respective temperature states of the respective catalysts in a case where a third temperature condition that both the oxidation catalyst and the SCR catalyst are at a temperature state higher than the low temperature state at the time of performing the deceleration fuel cut is established.

3 . The exhaust purification device of an engine according to claim 2 further comprising:
a first exhaust temperature sensor which detects a temperature of the exhaust gas which flows upstream of the oxidation catalyst; and
a second exhaust temperature sensor which detects the temperature of the exhaust gas which flows between the oxidation catalyst and the SCR catalyst,
wherein the controller is configured to determine the temperature state of the oxidation catalyst and the temperature state of the SCR catalyst based on respective detection temperatures of the first and second exhaust temperature sensors.

4 . The exhaust purification device of an engine according to claim 3 , wherein
the controller is configured to determine that the first temperature condition is established in a case where the detection temperature of the first exhaust temperature sensor is below a preset first threshold value and the detection temperature of the second exhaust temperature sensor is below a preset second threshold value, the controller is configured to determine that the second temperature condition is established in a case where the detection temperature of the first exhaust temperature sensor is below the first threshold value and the detection temperature of the second exhaust temperature sensor is equal to or above the second threshold value, and the controller is configured to determine that the third temperature condition is established in a case where the detection temperature of the first exhaust temperature sensor is equal to or above the first threshold value.

5 . The exhaust purification device of an engine according to claim 1 , wherein
the engine includes an intake passage through which air introduced into the engine body flows, the control valve is a throttle valve openably and closably disposed in the intake passage, and the controller is configured to lower an opening degree of the throttle valve at the time of performing the first flow regulating control.

6 . The exhaust purification device of an engine according to claim 5 , wherein
the engine includes: an EGR passage which makes the intake passage and the exhaust passage communicate with each other; and an EGR valve disposed openably and closably in the EGR passage, and the controller is configured to bring the EGR valve into a valve open state at the time of performing the first flow regulating control.

7 . The exhaust purification device of an engine according to claim 6 , wherein
the controller is configured to lower an opening degree of the EGR valve without lowering the opening degree of the throttle valve at the time of performing the second flow regulating control.

8 . 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.

9 . The vehicle engine according to claim 8 , wherein
the controller is configured to maintain the opening degree of the EGR valve at the same opening degree as the opening degree immediately before starting the deceleration fuel cut at the time of performing the first flow regulating control.

10 . The vehicle engine according to claim 8 , wherein
the controller is configured to maintain the opening degree of the throttle valve at the same opening degree as the opening

Assignees

• Mazda Motor

Inventors

• Katsuta Masato
• Uesugi Yasunori
• Minamoto Hiroshi

Classifications

• F01N2900/08

  said parameters being related to the engine · CPC title

• F01N2900/1602

  Temperature of exhaust gas apparatus · CPC title

• F01N2900/1411

  Exhaust gas flow rate, e.g. mass flow rate or volumetric flow rate · CPC title

• F01N2560/14

  having more than one sensor of one kind · CPC title

• F01N2240/36

  an exhaust flap · CPC title