Control apparatus and method for internal combustion engine

• US 20070199305A1
• Filed: 02/23/2007
• Published: 08/30/2007
• Est. Priority Date: 02/24/2006
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Hoshi, Koichi
• Granted Patent: US 7,836,683 B2
• Time in Patent Office: Days
• US Class Current: 60/285
• CPC Class Codes: F01N 13/009 having two or more separate purifying devices arranged in series
• CPC Class Codes: F01N 13/011 having two or more purifying devices arranged in parallel
• CPC Class Codes: F02D 2200/0804 Estimation of the temperature of the exhaust gas treatment apparatus
• CPC Class Codes: F02D 41/0082 per groups or banks F02D41/0087 takes precedence
• CPC Class Codes: F02D 41/0087 Selective cylinder activation, i.e. partial cylinder operation deceleration cut-off F02D41/123
• CPC Class Codes: F02D 41/0235 in relation with the state of the exhaust gas treating apparatus control of exhaust gas treating apparatus per se F01N
• CPC Class Codes: F02D 41/123 the fuel injection being cut-off

Abstract

A control apparatus for an internal combustion engine that includes right and left banks, first and second catalysts provided in the right and left exhaust pipes, respectively, and a downstream catalyst provided in a common exhaust pipe downstream of the upstream catalysts is adapted to alternately switch execution of catalyst degradation minimization and execution of fuel cut between the two banks if at least one of the temperature of the first catalyst and temperature of the second catalyst is higher than a predetermined value during deceleration of the internal combustion engine.

Claims

1. A control apparatus for an internal combustion engine including:

a first cylinder group;

a second cylinder group;

a first exhaust passage provided for the first cylinder group;

a second exhaust passage provided for the second cylinder group;

a first upstream catalyst provided in the first exhaust passage;

a second upstream catalyst provided in the second exhaust passage; and

a downstream catalyst provided in a third exhaust passage provided downstream of a confluence of the first exhaust passage and the second exhaust passage, the confluence being located downstream of the first upstream catalyst and the second upstream catalyst, the control apparatus comprising;

a fuel supply suspending portion that suspends supply of fuel to at least one of the first cylinder group and the second cylinder group under a predetermined state of the internal combustion engine;

a fuel supply suspension prohibiting portion that prohibits execution of the fuel supply suspension control by the fuel supply suspending portion when at least one of a temperature of the first upstream catalyst and a temperature of the second upstream catalyst is higher than a predetermined value; and

a fuel supply suspension prohibition switching portion that alternately switches the cylinder group in which the fuel supply suspension prohibiting control is executed by the fuel supply suspension prohibiting portion between the first cylinder group and the second cylinder group.

2. The control apparatus according to claim 1, wherein:

the internal combustion engine is a V-type multi-cylinder engine;

the first cylinder group is in a first bank of the V-type multi-cylinder engine; and

the second cylinder group is in a second bank of the V-type multi-cylinder engine.

3. The control apparatus according to claim 1, further comprising:

an air-fuel ratio controlling portion that controls an air-fuel ratio in the cylinder group in which the fuel supply suspension prohibiting control is executed by the fuel supply suspension prohibiting portion to a stoichiometric air-fuel ratio.

4. The control apparatus according to claim 1, further comprising:

a fuel supply suspension time calculating portion that calculates a total time of the fuel supply suspending control by the fuel supply suspending portion, wherein the fuel supply suspension prohibition switching portion switches the cylinder group in which the fuel supply suspending control is executed from one of the first cylinder group and the second cylinder group to the other if the total time calculated by the fuel supply suspension time calculating portion is longer than a predetermined value.

5. The control apparatus according to claim 1, further comprising:

a first oxygen concentration obtaining portion that obtains an oxygen concentration in the first upstream catalyst;

a second oxygen concentration obtaining portion that obtains an oxygen concentration in the second upstream catalyst; and

a running time obtaining portion that obtains a running time, wherein the fuel supply suspension prohibition switching portion switches the cylinder group for the fuel supply suspension based on a reference value reflecting at least one of a catalyst temperature in the cylinder group in which the fuel supply suspending control is being executed, an oxygen concentration in the same cylinder group, and a running time.

6. The control apparatus according to claim 1, further comprising:

a first catalyst degradation degree estimating portion that estimates the degree of degradation of the first upstream catalyst;

a second catalyst degradation degree estimating portion that estimates the degree of degradation of the second upstream catalyst; and

a degradation degree comparing portion that compares the degree of degradation of the first upstream catalyst and the degree of degradation of the second upstream catalyst, wherein the fuel supply suspension prohibiting portion executes the fuel supply suspension prohibiting control in the cylinder group with the catalyst that the degradation degree comparing portion determines to have degraded to a higher degree.

7. The control apparatus according to claim 1, further comprising:

an EGR control portion that controls the amount of re-circulated exhaust gas, wherein the EGR control portion makes the amount of re-circulated exhaust gas for the cylinder group in which the fuel supply suspension prohibiting control is executed larger than the amount of re-circulated exhaust gas for the other cylinder group.

8. The control apparatus according to claim 1, wherein the fuel supply suspending portion suspends supply of fuel to at least one of the first cylinder group and the second cylinder group during deceleration of the internal combustion engine.

9. The control apparatus according to claim 1, wherein the fuel supply suspension prohibiting portion estimates the temperature of the first upstream catalyst based on at least one of the amount of intake air supplied to the first cylinder group and the engine speed in the first cylinder group, and estimates the temperature of the second upstream catalyst based on at least one of the amount of intake air supplied to the second cylinder group and the engine speed in the second cylinder group.

10. The control apparatus according to claim 6, further comprising:

a first oxygen concentration obtaining portion that obtains an oxygen concentration in the first upstream catalyst;

a second oxygen concentration obtaining portion that obtains an oxygen concentration in the second upstream catalyst; and

a degradation degree comparing portion that compares the degree of degradation of the first upstream catalyst and the degree of degradation of the second upstream catalyst, wherein;

the first catalyst degradation degree estimating portion calculates a maximum adsorbed oxygen amount of the first upstream catalyst based on a target air-fuel ratio for the first cylinder group and the oxygen concentration in the first upstream catalyst that is obtained by the first oxygen concentration obtaining portion, and estimates the degree of degradation of the first upstream catalyst based on the maximum adsorbed oxygen amount of the first upstream catalyst; and

the second catalyst degradation degree estimating portion calculates a maximum adsorbed oxygen amount of the second upstream catalyst based on a target air-fuel ratio for the second cylinder group and the oxygen concentration in the second upstream catalyst that is obtained by the second oxygen concentration obtaining portion, and estimates the degree of degradation of the second upstream catalyst based on the maximum adsorbed oxygen amount of the second upstream catalyst.

11. The control apparatus according to claim 10, wherein:

the first catalyst degradation degree estimating portion makes the degree of degradation of the first upstream catalyst higher as the maximum adsorbed oxygen amount of the first upstream catalyst is smaller; and

the second catalyst degradation degree estimating portion makes the degree of degradation of the second upstream catalyst higher as the maximum adsorbed oxygen amount of the second upstream catalyst is smaller.

12. A control method for an internal combustion engine including:

a first cylinder group;

a second cylinder group;

a first exhaust passage provided for the first cylinder group;

a second exhaust passage provided for the second cylinder group;

a first upstream catalyst provided in the first exhaust passage;

a second upstream catalyst provided in the second exhaust passage; and

a downstream catalyst provided in a third exhaust passage provided downstream of a confluence of the first exhaust passage and the second exhaust passage, the confluence being located downstream of the first upstream catalyst and the second upstream catalyst, the control method comprising;

suspending supply of fuel to at least one of the first cylinder group and the second cylinder group under a predetermined state of the internal combustion engine;

prohibiting execution of the fuel supply suspension control when at least one of a temperature of the first upstream catalyst and a temperature of the second upstream catalyst is higher than a predetermined value; and

alternately switching the cylinder group in which the fuel supply suspension prohibiting control is executed between the first cylinder group and the second cylinder group.

13. A control apparatus for an internal combustion engine including:

a first cylinder group;

a second cylinder group;

a first exhaust passage provided for the first cylinder group;

a second exhaust passage provided for the second cylinder group;

a first upstream catalyst provided in the first exhaust passage;

a second upstream catalyst provided in the second exhaust passage; and

a downstream catalyst provided in a third exhaust passage provided downstream of a confluence of the first exhaust passage and the second exhaust passage, the confluence being located downstream of the first upstream catalyst and the second upstream catalyst, the control apparatus comprising;

fuel supply suspending means for suspending supply of fuel to at least one of the first cylinder group and the second cylinder group under a predetermined state of the internal combustion engine;

fuel supply suspension prohibiting means for prohibiting execution of the fuel supply suspension control by the fuel supply suspending means when at least one of a temperature of the first upstream catalyst and a temperature of the second upstream catalyst is higher than a predetermined value; and

fuel supply suspension prohibition switching means for alternately switching the cylinder group in which the fuel supply suspension prohibiting control is executed by the fuel supply suspension prohibiting means between the first cylinder group and the second cylinder group.