Controlling device for purifying exhaust gas purifying
View Patent ↗A controlling device for purifying exhaust gas includes: a fuel cutting controller ( 2 ) that, if a predetermined condition for fuel cutting is satisfied, shuts off supply of fuel to an engine ( 10 ) after a predetermined delay time (B) elapses; a calculator ( 3 ) that calculates oxygen occludability of a catalyst ( 6, 7 ) being interposed in an exhaust system of the engine ( 10 ) and containing an oxygen occludable material; and a setter ( 4 ) that sets a length of the delay time (B) in accordance with the oxygen occludability calculated by the calculator ( 3 ).
1. A controlling device for purifying exhaust gas comprising:
a fuel cutting controller that, if a predetermined condition for fuel cutting is satisfied, shuts off supply of fuel to an engine after a delay time elapses;
a calculator that calculates oxygen occludability of a catalyst being interposed in an exhaust system of the engine and containing an oxygen occludable material; and
a setter that variously sets a length of the delay time in accordance with the oxygen occludability calculated by the calculator.
2. The controlling device according to claim 1 , wherein the setter sets the delay time to be shorter as the oxygen occludability is lower.
3. The controlling device according to claim 1 , further comprising:
an upstream sensor that detects an oxygen concentration of an upstream side of the catalyst; and
a downstream sensor that detects an oxygen concentration of a downstream side of the catalyst, wherein
the calculator determines that the oxygen occludability is lower as an output inverting time representing a time period from a response time of the upstream sensor to a change of an air-fuel ratio to a response time of the downstream sensor to the change of the air-fuel ratio is shorter.
4. The controlling device according to claim 2 , further comprising:
an upstream sensor that detects an oxygen concentration of an upstream side of the catalyst; and
a downstream sensor that detects an oxygen concentration of a downstream side of the catalyst, wherein
the calculator determines that the oxygen occludability is lower as an output inverting time representing a time period from a response time of the upstream sensor to a change of an air-fuel ratio to a response time of the downstream sensor to the change of the air-fuel ratio is shorter.
5. The controlling device according to claim 3 , wherein:
the catalyst comprises an upstream catalyst disposed on an upstream side in the exhaust system and a downstream catalyst disposed on a downstream side in the exhaust system;
the controlling device further comprises an intermediate sensor that detects an oxygen concentration between the upstream catalyst and the downstream catalyst; and
the calculator determines that the oxygen occludability is lower as a second output inverting time representing a time period from a response time of the upstream sensor to a change of the air-fuel ratio to a response time of the intermediate sensor to the change of the air-fuel ratio is shorter.
6. The controlling device according to claim 4 , wherein:
the catalyst comprises an upstream catalyst disposed on an upstream side in the exhaust system and a downstream catalyst disposed on a downstream side in the exhaust system;
the controlling device further comprises an intermediate sensor that detects an oxygen concentration between the upstream catalyst and the downstream catalyst; and
the calculator determines that the oxygen occludability is lower as a second output inverting time representing a time period from a response time of the upstream sensor to a change of the air-fuel ratio to a response time of the intermediate sensor to the change of the air-fuel ratio is shorter.
7. The controlling device according to claim 1 , wherein the calculator calculates the oxygen occludability based on a degree of aged deterioration of the catalyst.
8. The controlling device according to claim 2 , wherein the calculator calculates the oxygen occludability based on a degree of aged deterioration of the catalyst.
9. The controlling device according to claim 1 , wherein the calculator calculates the oxygen occludability when a condition that an operating state of the engine is stable for a predetermined time is satisfied.
10. The controlling device according to claim 2 , wherein the calculator calculates the oxygen occludability when a condition that an operating state of the engine is stable for a predetermined time is satisfied.
11. The controlling device according to claim 1 , wherein the calculator calculates the oxygen occludability when a condition that temperature of the catalyst is within a predetermined temperature range.
12. The controlling device according to claim 2 , wherein the calculator calculates the oxygen occludability when a condition that temperature of the catalyst is within a predetermined temperature range.