Vehicle and control method thereof

Abstract

When both catalyst degradation and catalyst odor need to be suppressed when a fuel cut condition is satisfied, a fuel cut control is executed giving priority to control for suppressing catalyst odor, though a required air amount G* for idling is drawn in at that time. Therefore, when shifting the engine into an idle state to suppress catalyst degradation after the catalyst odor has been eliminated, the required air amount G* for idling is already being drawn in so there is no need to adjust the air amount. As a result, there is no time delay for air amount adjustment. Therefore, after the control to suppress catalyst odor has ended, a smooth shift can be made into control to suppress degradation of the exhaust gas control catalyst.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and further objects, features and advantages of the invention will become apparent from the following description of preferred embodiments with reference to the accompanying drawings, wherein like numerals are used to represent like elements and wherein:

FIG. 1 is a block diagram schematically showing the structure of a hybrid vehicle according to one example embodiment of the invention;

FIG. 2 is a block diagram schematically showing the structure of an engine in the hybrid vehicle shown in FIG. 1;

FIGS. 3A, 3B is a flowchart illustrating one example of a control routine during braking, which is executed by a hybrid electronic control unit according to the example embodiment;

FIG. 4 is a flowchart illustrating an example of a routine for setting a catalyst degradation suppression flag which is executed by an engine electronic control unit according to the example embodiment;

FIG. 5 is a flowchart illustrating an example of a routine for setting a catalyst odor suppression flag which is executed by the engine electronic control unit according to the example embodiment;

FIG. 6 is a chart showing an example of a map used for setting required braking torque;

FIG. 7 is a view of one example of an alignment graph showing the mechanical relationship between torque and rotation speed of rotating elements of a power split device during braking that occurs with a fuel cut of the engine;

FIG. 8 is a flowchart illustrating an example of a control routine for suppressing catalyst degradation, which is executed by the engine electronic control unit according to the example embodiment;

FIG. 9 is a flowchart illustrating an example of a fuel cut control routine which is executed by the engine electronic control unit according to the example embodiment;

FIG. 10 is a block view schematically showing the structure of a hybrid vehicle according to a modified example of the example embodiment; and

FIG. 11 is a block diagram schematically showing the structure of a hybrid vehicle according to another modified example of the example embodiment.

Claims

1. A vehicle comprising: an internal combustion engine that burns a mixture of air and fuel;an exhaust gas control catalyst that purifies exhaust gas discharged from the internal combustion enginea fuel injection apparatus that injects fuel into the internal combustion engine;an air amount adjusting apparatus that adjusts the amount of air drawn into the internal combustion engine; anda control apparatus which, when a catalyst degradation condition and a catalyst odor producing condition are satisfied when a fuel cut condition is satisfied, sets a required air amount for idling based on an operating state of the vehicle, adjusts the air amount adjusting apparatus such that the required air amount is drawn in, and controls the fuel injection apparatus such that a fuel cut is performed, and when a predetermined catalyst odor eliminated condition is satisfied thereafter, controls the fuel injection apparatus and the air amount adjusting apparatus such that the internal combustion engine idles.

2. The vehicle according to claim 1, wherein the control apparatus makes the fuel cut condition a condition in which the speed of the internal combustion engine is in a predetermined high speed region and required braking torque is being generated.

3. The vehicle according to claim 1, wherein the control apparatus makes the catalyst degradation condition a condition in which the temperature of the exhaust gas control catalyst has reached a predetermined high temperature region.

4. The vehicle according to claim 1, wherein the control apparatus makes the catalyst odor producing condition a condition in which a total increase injection amount of fuel injected from the fuel injection apparatus has reached a predetermined large amount region.

5. The vehicle according to claim 1, wherein the control apparatus makes the catalyst odor eliminated condition a condition in which a cumulative value of the amount of air drawn into the internal combustion engine for a period of time during which the fuel cut is performed has reached a predetermined large air amount region.

6. The vehicle according to claim 1, wherein the air amount adjusting apparatus includes a throttle valve mounted such that an opening amount thereof is variable in an intake pipe of the internal combustion engine, and an actuator that changes the opening amount of the throttle valve by driving the throttle valve

7. The vehicle according to claim 1, wherein when the control apparatus sets the required air amount for idling based on the operating state of the vehicle, adjusts the air amount adjusting apparatus such that the required air amount is drawn in, and controls the fuel injection apparatus such that a fuel cut is performed, and the required air amount enters a predetermined small amount region, the control apparatus changes the required air amount to become a value that exceeds that small amount region.

8. The vehicle according to claim 1, wherein when the control apparatus sets the required air amount for idling based on the operating state of the vehicle, the control apparatus sets the required air amount for idling based on the speed of the internal combustion engine.

9. A control method for a vehicle that includes an internal combustion engine that burns a mixture of air and fuel, an exhaust gas control catalyst that purifies exhaust gas discharged from the internal combustion engine, fuel injecting means (126) for injecting fuel into the internal combustion engine, and air amount adjusting means for adjusting the amount of air drawn into the internal combustion engine, comprising the steps of: (a) when a catalyst degradation condition and a catalyst odor producing condition are satisfied when a fuel cut condition is satisfied, setting a required air amount for idling based on an operating state of the vehicle, adjusting the air amount adjusting means such that the required air amount is drawn in, and controlling the fuel injecting means such that a fuel cut is performed; and(b) when a predetermined catalyst odor eliminated condition is satisfied after step (a), controlling the fuel injecting means and the air amount adjusting means such that the internal combustion engine idles.