Controller of compression-ignition engine

• US 6,772,585 B2
• Filed: 09/27/2002
• Issued: 08/10/2004
• Est. Priority Date: 09/28/2001
• Status: Expired due to Term

• Current Assignee: Hitachi Astemo Ltd. (Hitachi, Ltd.)
• Original Assignee: Hitachi, Ltd.
• Inventors: Ohsuga, Minoru, Yamaoka, Shiro, Iihoshi, Yoichi
• Primary Examiner(s): Tran, Binh Q.
• Application Number:
  US10/255,703
• Publication Number:
  US 20030061803A1
• Time in Patent Office: 683 Days
• Field of Search: 602/74, 602/76, 602/77, 602/85, 602/86, 602/95, 602/97, 603/01, 123/300, 123/305, 123/688, 123/295
• US Class Current: 60/277
• CPC Class Codes: F02B 1/12 with compression ignition with fuel-air charge ignited by compression ignition of an additional fuel F02B7/00
• CPC Class Codes: F02D 2041/0017 by simultaneous control of throttle and exhaust gas recirculation
• CPC Class Codes: F02D 41/0057 Specific combustion modes combustion modes per se F02D41/3017
• CPC Class Codes: F02D 41/006 using internal EGR control of valve overlap for internal EGR F02D13/0261; arrangements for internal EGR F02M26/01
• CPC Class Codes: F02D 41/0087 Selective cylinder activation, i.e. partial cylinder operation deceleration cut-off F02D41/123
• CPC Class Codes: F02D 41/0295 Control according to the amount of oxygen that is stored on the exhaust gas treating apparatus
• CPC Class Codes: F02D 41/1402 Adaptive control
• CPC Class Codes: F02D 41/1441 Plural sensors
• CPC Class Codes: F02D 41/1454 the characteristics being an oxygen content or concentration or the air-fuel ratio
• CPC Class Codes: F02D 41/146 the characteristics being an NOx content or concentration
• CPC Class Codes: F02D 41/1465 with determination means using an estimation
• CPC Class Codes: F02D 41/222 relating to the failure of sensors or parameter detection devices
• CPC Class Codes: F02D 41/2441 characterised by the learning conditions
• CPC Class Codes: F02D 41/2454 Learning of the air-fuel ratio control
• CPC Class Codes: F02D 41/3011 according to or using specific or several modes of combustion
• CPC Class Codes: F02D 41/3035 a mode being the premixed charge compression-ignition mode
• CPC Class Codes: F02D 41/3064 with special control during transition between modes
• CPC Class Codes: F02D 41/402 Multiple injections
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A control system for a compression injection engine can prevent deterioration in exhaust purification at the time of the switching of combustion between spark ignition and compression ignition, at the time of said spark ignition combustion and said compression injection combustion, and can diagnose any deterioration of an NO x detector and a three way catalyst. The control system includes a catalytic converter installed within an exhaust passage of the compression ignition engine for compressing and igniting a pre-mixture of a fuel and air, an air/fuel ratio detector for detecting an air/fuel ratio at upstream side of said catalytic converter, and an NO_x detector for detecting NO_x at downstream side of said catalytic converter.

Claims

1. A control system for a compression ignition engine comprising:

an ignition coil for igniting a spark;

a catalytic converter installed within an exhaust passage of the compression ignition engine, said compression engine functioning in a compression ignition mode and an spark ignition compression mode for compressing and igniting a pre-mixture of a fuel and air;

an air/fuel ratio detector for detecting an air/fuel ratio at upstream side of said catalytic converter; and

an NO_x detector for detecting NO_x at downstream side of said catalytic converter.

2. A control system for a compression ignition engine as set forth in claim 1, wherein said control system uses an output signal of said NO_x detector for preventing deterioration of exhaust gas purification performance.

3. A control system for a compression ignition engine as set forth in claim 1, wherein said control system prevents deterioration of exhaust gas purification performance using an output signal of said NO_x detection upon switching transition of combustion mode between said spark ignition mode and said compression ignition mode, during spark ignition mode combustion and during compression ignition mode combustion.

4. A control system for a compression ignition engine as set forth in claim 1, wherein said control system further comprises:

combustion mode switching means for switching between a spark ignition mode and compression ignition mode;

exhaust deterioration factor predicting means for predicting a factor causing deterioration of exhaust gas purification performance on the basis of an NO_x detection value upon switching transition of the combustion mode; and

switching learning means for leaning control amount and control object of said combustion mode switching means on the basis of said factor causing deterioration of exhaust gas purification performance.

5. A control system for a compression ignition engine as set forth in claim 4, wherein said switching learning means learns a spark ignition timing.

6. A control system for a compression ignition engine as set forth in claim 4, wherein said switching learning means learns a throttle valve control amount.

7. A control system for a compression ignition engine as set forth in claim 4, wherein said switching learning means learns a fuel injection amount.

8. A control system for a compression ignition engine as set forth in claim 4, wherein said switching leaning means learns a fuel cut-off period before switching to said compression ignition mode combustion.

9. A control system for a compression ignition engine as set forth in claim 4, wherein said switching learning means learns one of a target intake air flow rate and a target EGR amount.

10. A control system for a compression ignition engine as set forth in claim 4, wherein said switching learning means learns an engine operational range for switching combustion mode between said spark ignition mode combustion and said compression ignition mode combustion.

11. A control system for a compression ignition engine as set forth in claim 1, wherein said control system performs fuel injection between an expansion stroke and an exhaust stroke in said compression ignition mode combustion.

12. A control system for a compression ignition engine as set forth in claim 1, wherein said control system comprises:

air/fuel ratio control means for controlling an output of said air/fuel ratio detector toward a target air/fuel ratio;

a target air/fuel ratio calculating means for calculating said target air/fuel ratio for optimizing purification ratio of said catalytic converter,

said target air/fuel ratio calculating means calculates said target air/fuel ratio on the basis of an output signal of said NO_x detector.

13. A control system for a compression ignition engine as set forth in claim 12, wherein said control system temporarily sets said target air/fuel ratio rich side when said NO_x detection value exceeds a predetermined value.

14. A control system for a compression ignition engine as set forth in claim 1, wherein said control system comprises NO_x detector diagnosis means for diagnosing abnormality of said NO_x detector for controlling the air/fuel ratio so that an output of said air-fuel ratio detector becomes stoichiometric value.

15. A control system for a compression ignition engine as set forth in claim 1, wherein said control system comprises combustion deterioration detecting means for detecting deterioration of combustion on the basis of an NO_x detection value in said compression ignition mode combustion.

16. A control system for a compression ignition engine as set forth in claim 15, wherein said combustion deterioration detecting means detects deterioration of combustion in said compression ignition mode combustion when an output of said air/fuel ratio detector indicates a lean mixture condition.

17. A control system for a compression ignition engine as set forth in claim 15, wherein said control system comprises combustion improvement control means for controlling improvement of combustion in said compression ignition mode when deterioration of combustion is detected by said combustion deterioration detecting means.

18. A control system for a compression ignition engine as set forth in claim 17, wherein said control system controls the air/fuel ratio so that the output of said air/fuel ratio detector becomes stoichiometric value when deterioration of combustion is detected by said exhaust deterioration detecting means after implementation of said combustion improvement control means.

19. A control system for a compression ignition engine as set forth in claim 1, wherein said control system comprises air/fuel ratio detector diagnosing means for detecting abnormality of said air/fuel ratio detector, for correcting a fuel injection amount on the basis of said output signal of said NO_x detector when abnormality of said air/fuel ratio detector is detected.

20. A control system for a compression ignition engine as set forth in claim 1, wherein said control system prevents deterioration of exhaust gas purification performance by detecting fatigue of at least one of said NO_x detector and said catalytic converter.

21. A control system for a compression ignition engine as set forth in claim 20, wherein said control system comprises fuel cut-off means for interrupting fuel injection during deceleration, and fatigue of NO_x detector is detected on the basis of the output signal of said NO_x detector during fuel cut-off.

22. A control system for a compression ignition engine as set forth in claim 21, wherein said control system comprises fuel recovery means for recovering fuel injection after fuel cut-off, abnormality of said NO_x detector is judged when a difference said NO_x detection value during fuel recovery and said NO_x detection value during fuel cut-off is less than or equal to a predetermined value.

23. A control system for a compression ignition engine as set forth in claim 20, wherein said control system comprises air/fuel ratio control means for controlling air/fuel ratio so that an output of said air/fuel ratio detector becomes close to a target air/fuel ratio, for diagnosis of fatigue of said catalytic converter on the basis of the output signal of said NO_x detector when said target air/fuel ratio is set at stoichiometric value.

24. An automotive vehicle having a control system for a compression ignition engine defined in claim 1.