Exhaust gas purification system for hybrid vehicle

Abstract

An exhaust gas purification system for a hybrid vehicle is disclosed. An internal combustion engine and an electric motor are each arranged for providing power output for the vehicle. An exhaust gas purification device is provided in an exhaust gas passage of the engine to treat exhaust gas components contained in the exhaust gas from the engine. A controller is arranged and configured to selectively perform a regeneration operation of the exhaust gas purification device to burn and remove deposits accumulated in the exhaust gas purification device. The controller is further arranged and configured to control the internal combustion engine and the electric motor such that the exhaust gas purification device is restrained from reaching an excessive temperature during the regeneration operation of the exhaust gas purification device.

Description

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a system diagram of a hybrid vehicle according to one embodiment of the present invention.

FIG. 2 is a block diagram for controlling the hybrid vehicle of FIG. 1.

FIG. 3 is a graph engine/motor output allocation versus total output that may be derived from an output allocation table as may be used under a normal vehicle operation mode (M=1).

FIG. 4 is a graph of torque versus rotation speed as may be derived from an internal combustion engine operating point table for optimum fuel consumption.

FIG. 5 is a graph of torque versus rotation speed as may be derived from an electric motor operating point table.

FIG. 6 is a graph engine/motor output allocation versus total output that may be derived from an output allocation table as may be used under a motor-based driving mode (M=2).

FIG. 7 is a graph of torque versus rotation speed as may be derived from an internal combustion engine operating point table as may be used under a motor-based driving mode (M=2).

FIG. 8 is a graph engine/motor output allocation versus total output that may be derived from an output allocation table as may be used under a charge level increasing mode (M=3).

FIG. 9 is a graph of battery state of charge (SOC) target value (Et) versus PM deposition count (C).

FIG. 10 is a graph showing a relationship between the output power boundaries limits values and the degree of divergence from the SOC target value.

FIG. 11 is a flowchart showing a control process.

FIG. 12 is a comparison time plot showing a plurality of control process parameters as a function of time for a control process as shown in the flowchart of FIG. 11.

FIG. 13 is a graph of battery state of charge (SOC) target versus PM deposition count according to another example.

FIG. 14 is a system diagram of a series type hybrid vehicle.

FIG. 15 a graph of torque versus rotation speed as may be derived from an electric motor operating point table that may be used with the series type hybrid vehicle.

FIG. 16 is a graph of SOC target value (Et) versus sulfur deposition count (C).

FIG. 17 is a block diagram for controlling a hybrid vehicle according to an alternative embodiment.

FIG. 18 is a graph of engine/motor output allocation versus total output that may be derived from an output allocation table as may be used under an engine output increasing mode (M=4).

FIG. 19 is a graph of torque versus rotation speed as may be derived from an internal combustion engine operating point table as may be used under an engine output increasing mode (M=4).

FIG. 20 is a graph of engine/motor output allocation versus total output that may be derived from an output allocation table as may be used under a motor output increasing mode (M=5).

FIG. 21 is a graph of torque versus rotation speed as may be derived from an internal combustion engine operating point table as may be used under the motor output increasing mode (M=5).

FIG. 22 is a flowchart showing a control process for an alternative embodiment.

FIG. 23 is a comparison time plot showing a plurality of control process parameters as a function of time for a control process as shown in the flowchart of FIG. 22 for an alternative embodiment.

Claims

1. An exhaust gas purification system for a hybrid vehicle comprising: an internal combustion engine and an electric motor each arranged for providing power output for the vehicle,an exhaust gas purification device disposed in an exhaust passage of the engine to treat exhaust gas components contained in exhaust gas from the engine,a controller arranged and configured to selectively perform a regeneration operation of the exhaust gas purification device to burn and remove deposits accumulated in the exhaust gas purification device, andthe controller further arranged and configured to control the engine and the electric motor such that the exhaust gas purification device is restrained from reaching an excessive temperature during the regeneration operation of the exhaust gas purification device.

2. The exhaust gas purification system of claim 1, wherein a rotational speed of the engine is increased by an increase in the power output of the electric motor to prevent the exhaust gas purification device from reaching the excessive temperature, when the regeneration operation of the exhaust gas purification device is completed.

3. The exhaust gas purification system of claim 2, wherein the rotational speed of the engine is controlled to be greater than or equal to a predetermined rotational speed when the increase in the power output of the electric motor to prevent the exhaust purification device from reaching the excessive temperature is performed.

4. The exhaust gas purification system of claim 3, wherein the power output of the engine is reduced when the increase in the power output of the electric motor to prevent the exhaust purification device from reaching the excessive temperature is performed.

5. The exhaust gas purification system of claim 4, wherein the increase in the power output of the electric motor to prevent the exhaust purification device from reaching the excessive temperature is continued until a temperature of the exhaust gas purification device drops to a predetermined temperature.

6. The exhaust gas purification system of claim 2 wherein a time to start the increase in the power output of the electric motor to prevent the exhaust purification device from reaching the excessive temperature is determined based upon an amount of the deposits accumulated in the exhaust gas purification device.

7. The exhaust gas purification system of claim 2, further comprising a battery arranged and configured to be selectively charged with electric power generated by the electric motor that is capable of being driven by the engine, andwherein the controller is further arranged and configured to control the engine by an increase in the power output of the engine to increase a state of charge of the battery before the increase in the power output of the electric motor to prevent the exhaust purification device from reaching the excessive temperature.

8. The exhaust gas purification system of claim 7, wherein the state of charge of the battery is controlled to a target charge value that is determined based upon an amount of the deposits accumulated in the exhaust gas purification device.

9. The exhaust gas purification system of claim 8, wherein the target charge value becomes larger as the amount of the deposits decreases.

10. The exhaust gas purification system of claim 7, wherein the control to increase the state of charge of the battery is performed with a compensation related to a distribution of the power output of the engine with respect to a requested total power output for the vehicle, the compensation being adapted to either increase an upper limit value of power output of the engine, decrease the requested total power output where the engine starts power output with respect to the requested total power output, or increase the power output of the engine with respect to either the requested total power output or the power output of the electric motor.

11. The exhaust gas purification system of claim 10, wherein the state of charge of the battery is controlled to a target charge value that is determined based upon an amount of the deposits accumulated in the exhaust gas purification; anda compensation amount of the compensation is determined according to a deviation amount between the target charge value and an actual charge value.

12. The exhaust gas purification system of claim 11, wherein the compensation is performed when the actual charge value is lower than the target charge value, but is prohibited to perform when the actual charge value is higher than the target charge value.

13. The exhaust gas purification system of claim 1, further comprising a section to determine the excessive temperature of the exhaust gas purification device, and wherein when the excessive temperature of the exhaust gas purification device is detected during the regeneration operation, the engine is controlled to increase the power output with a rich air-fuel ratio operation and an excess power output caused by the increase in the power output of the engine is used to generate electric power by the electric motor.

14. The exhaust gas purification system of claim 1, wherein the exhaust gas purification system further comprises a section to determine the excessive temperature of the exhaust gas purification device, andwhen the excessive temperature of the exhaust gas purification device is detected during the regeneration operation, the power output of the electric motor is increased so as to increase a rotational speed of the engine.

15. The exhaust gas purification system of claim 14, wherein the rotational speed of the engine is increased to be greater than or equal to a predetermined rotational speed when the excessive temperature of the exhaust gas purification device is detected during the regeneration operation.

16. The exhaust gas purification system of claim 14, wherein the power output of the engine is decreased when the excessive temperature of the exhaust gas purification device is detected during the regeneration operation.

17. The exhaust gas purification system of claim 13 further comprising: a battery connected to the electric motor, anda detecting section to determine a state of charge of the battery, andwherein, when the excessive temperature of the exhaust gas purification device is detected during the regeneration operation, a selection is made according to the state of charge as to whether the engine is controlled to increase the power output of the engine with a rich air-fuel ratio operation and the excess power output caused by the increase in power output of the engine is used to generate electric power by the electric motor, or the power output of the electric motor is increased so as to increase the rotational speed of the engine.

18. The exhaust gas purification system of claim 17, wherein when switching between the control for increasing the power output of the engine and the control for increasing the power output of the electric motor, the engine is operated with a transition via a high speed rotation and high load range of the engine.

19. The exhaust gas purification system under 17, wherein the control for increasing the power output of the engine is carried out after the state of charge of the battery has dropped below a first level and until the state of charge of the battery increases to a second level that is set higher than the first level.

20. The exhaust gas purification system of claim 17, wherein the control for increasing the power output of the electric motor is carried out after the state of charge of the battery has increased higher than a second level and until the state of charge of the battery drops to a first level that is set lower than the second level.

21. The exhaust gas purification system of claim 19, wherein when the state of charge of the battery is between the first level and the second level when the excessive temperature of the exhaust gas purification device is first determined, the control for increasing the power output of the electric motor is carried out in priority to the control for increasing the power output of the engine.

22. The exhaust gas purification system of claim 19, wherein the first and the second levels are set lower as a temperature of the exhaust gas purification device becomes higher.

23. The exhaust gas purification system of claim 20, wherein when the state of charge of the battery is between the first level and the second level when the excessive temperature of the exhaust gas purification device is first determined, the control for increasing the power output of the electric motor is carried out in priority to the control for increasing the power output of the engine.

24. The exhaust gas purification system of claim 20, wherein the first and the second levels are set lower as a temperature of the exhaust gas purification device becomes higher.

25. An exhaust gas purification system for a hybrid vehicle equipped with an internal combustion engine and an electric motor each arranged for providing power outputs for the vehicle, the exhaust gas purification system comprising: purification means, disposed in an exhaust gas passage of an internal combustion engine, for purifying exhaust gas components contained in exhaust gas from the internal combustion engine, andcontrol means, operatively connected to the internal combustion engine and an electric motor, for performing a regeneration of the purification means by burning the deposits accumulated in the purification means such that the purification means is restrained from reaching an excessive temperature during the regeneration of the purification means.

26. A method for controlling an exhaust gas purification system for a hybrid vehicle equipped with an internal combustion engine and an electric motor each arranged for providing power outputs for the vehicle, comprising: performing a regeneration of an exhaust gas purification device disposed in an exhaust passage of an internal combustion engine to burn and remove deposits accumulated in the exhaust gas purification device, andcontrolling the internal combustion engine and an electric motor to restrain the exhaust gas purification device from reaching an excessive temperature during the regeneration of the exhaust gas purification device.