Controlled engine shutdown for a hybrid electric vehicle

• US 6,961,654 B2
• Filed: 05/03/2001
• Issued: 11/01/2005
• Est. Priority Date: 05/03/2001
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Peters, Mark William, Robichaux, Jerry D., Kotre, Stephen John, Boggs, David Lee
• Primary Examiner(s): Vo, Hieu T.
• Application Number:
  US09/848,492
• Publication Number:
  US 20020165660A1
• Time in Patent Office: 1,643 Days
• Field of Search: 701/112, 701/109, 701/108, 701/102, 123/198.DB, 123/520, 123/568.12, 123/679, 123/497, 123/478, 180/65.2, 180/65.8, 180/165
• US Class Current: 701/112
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60L 2240/441 Speed
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/15 Control strategies specially adapted for achieving a particular effect
• CPC Class Codes: B60W 2510/0638 Engine speed
• CPC Class Codes: B60W 2710/0616 Position of fuel or air injector
• CPC Class Codes: B60W 2710/0644 Engine speed
• CPC Class Codes: F02D 17/04 rendering engines inoperative or idling, e.g. caused by abnormal conditions dependent on lubricating conditions F01M1/22; dependent on cooling F01P5/14
• CPC Class Codes: F02D 37/02 one of the functions being ignition
• CPC Class Codes: F02D 41/0002 Controlling intake air
• CPC Class Codes: F02D 41/003 Adding fuel vapours, e.g. drawn from engine fuel reservoir
• CPC Class Codes: F02D 41/0055 Special engine operating conditions, e.g. for regeneration of exhaust gas treatment apparatus
• CPC Class Codes: F02D 41/042 for stopping the engine
• CPC Class Codes: F02D 41/123 the fuel injection being cut-off
• CPC Class Codes: F02M 25/08 adding fuel vapours drawn from engine fuel reservoir electrical control of purge system F02D41/003
• CPC Class Codes: Y02T 10/40 Engine management systems
• CPC Class Codes: Y02T 10/62 Hybrid vehicles

Abstract

A method and system to control engine shutdown in a hybrid electric vehicle (HEV) are provided. Tailpipe emissions are reduced during the many engine shutdowns and subsequent restarts during the course of an HEV drive cycle, and evaporative emissions are reduced during an HEV “soak” (inactive) period. The engine shutdown routine can ramp off fuel injectors, control engine torque (via electronic throttle control), control engine speed, stop spark delivery by disabling the ignition system, stop purge vapor flow by closing a vapor management valve (VMV), stop exhaust gas recirculation (EGR) flow by closing an EGR valve, and flush the intake manifold of residual fuel (vapor and puddles) into the combustion chamber to be combusted. The resulting exhaust gas byproducts are then converted in the catalytic converter.

Claims

1. A system to control an engine shutdown for a hybrid electric vehicle (HEV) wherein vehicle tailpipe and evaporative emissions are reduced, the system comprising:

at least one controller configured to control an engine shutdown routine, including controlling engine torque and controlling engine speed.

2. The system of claim 1, wherein the engine shutdown routine further includes:

ramping off fuel injectors;

stopping firing of spark plugs by disabling ignition system;

stopping purge flow from a vapor management valve (VMV);

stopping exhaust gas recirculation (EGR) flow from an EGR valve; and

flushing an engine intake manifold of residual fuel once all sources of fuel (injectors, VMV, and EGR valve) are halted.

3. The system of claim 2 further comprising an abort engine shutdown control if an engine is required to run again and fuel injector ramping has not yet begun.

4. The system of claim 2 further comprising a power sustain control after the engine and vehicle are “

keyed off”

to allow a generator to continue to spin the engine (after injectors are shut off) whereby residual fuel is flushed from the engine intake manifold into engine cylinders to be combusted, and then on to a hot catalytic converter to have the resulting exhaust gas byproducts converted.

5. The system of claim 2 wherein the fuel injectors are ramped off in a calibratable manner.

6. The system of claim 5 wherein a fuel injector calibration turns all injectors off at once.

7. The system of claim 5 wherein a fuel injector calibration turns one injector off at a time.

8. The system of claim 5 wherein a fuel injector calibration turns two injectors off at a time.

9. The system of claim 2 wherein a spark control shuts off spark when engine speed is less than some calibratable level.

10. The system of claim 1, wherein the controller is configured to control engine shutdown in two stages, the first stage including controlling engine torque and controlling engine speed.

11. A method to control an engine shutdown for a hybrid electric vehicle (HEV) comprising the steps of:

controlling engine torque; and

controlling engine speed.

12. The method of claim 11 further comprising the steps of:

ramping off fuel injectors;

stopping the firing of spark plugs by disabling an ignition system;

stopping purge flow from a vapor management valve (VMV);

stopping exhaust gas recirculation (EGR) flow from an EGR valve; and

flushing an engine intake manifold of residual fuel after halting all sources of fuel in the fuel injectors, VMV, and EGR valve.

13. The method of claim 12 further comprising the step of aborting the HEV engine shutdown if engine demand changes to require the engine to run again and fuel injector ramping has not yet begun.

14. The method of claim 12 further comprising the step of sustaining power after “

keying-off”

the engine and vehicle to allow a generator to continue spinning the engine (after injectors are shut off) whereby residual fuel is flushed from the engine intake manifold into engine cylinders to be combusted, and then on to a hot catalytic converter to have the resulting exhaust gas byproducts converted.

15. The method of claim 12 further comprising the step of shutting off spark when engine speed if less than a calibratable level.

16. The method of claim 12 wherein ramping off fuel injectors is done in a calibratable manner.

17. The method of claim 16 wherein ramping off fuel injectors turns one injector off at a time.

18. The method of claim 16 wherein ramping off fuel injectors turns two injectors off at a time.

19. The method of claim 12 wherein ramping off fuel injectors turns all injectors off at once.

20. The method of claim 11, wherein the engine shutdown is controlled in two stages, the first stage including controlling engine torque and controlling engine speed.