SYSTEM AND METHODS FOR IMPROVING FUEL ECONOMY

• US 20170306893A1
• Filed: 04/26/2016
• Published: 10/26/2017
• Est. Priority Date: 04/26/2016
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Leone, Thomas G., Miller, Kenneth James, Martin, Douglas Raymond
• Granted Patent: US 9,856,829 B2
• Time in Patent Office: Days
• CPC Class Codes: B60K 6/365 with the gears having orbital motion
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/24 including control of energy storage means
• CPC Class Codes: B60W 10/26 for electrical energy, e.g. batteries or capacitors
• 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 20/16 for reducing engine exhaust emissions
• CPC Class Codes: B60W 2030/206 related or induced by the engine
• CPC Class Codes: B60W 2510/068 Engine exhaust temperature
• CPC Class Codes: B60Y 2300/474 Catalyst warm up
• CPC Class Codes: F02B 37/16 by bypassing charging air
• CPC Class Codes: F02B 37/24 by using pumps or turbines with adjustable guide vanes
• CPC Class Codes: F02D 17/02 Cutting-out cutting-out engines in multiple engine arrangements F02D25/04
• CPC Class Codes: F02D 2200/101 Engine speed
• CPC Class Codes: F02D 2200/1012 Engine speed gradient
• CPC Class Codes: F02D 41/005 according to engine operating conditions
• CPC Class Codes: F02D 41/0087 Selective cylinder activation, i.e. partial cylinder operation deceleration cut-off F02D41/123
• CPC Class Codes: F02D 41/064 at cold start F02D41/067 takes precedence
• CPC Class Codes: F02D 41/123 the fuel injection being cut-off
• CPC Class Codes: F02M 26/01 : Internal exhaust gas recirculation, i.e. wherein the residual exhaust gases are trapped in the cylinder or pushed back from the intake or the exhaust manifold into the combustion chamber without the use of additional passages
• CPC Class Codes: F02M 26/43 : in which exhaust from only one cylinder or only a group of cylinders is directed to the intake of the engine
• CPC Class Codes: Y02T 10/40 : Engine management systems
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles

Abstract

Methods and systems are provided for controlling engine operation in a hybrid vehicle, where the vehicle engine comprises one or more cylinders dedicated to recirculating exhaust to the intake manifold. In one example, if an engine load decreases below a level where dedicated exhaust gas recirculation may lead to combustion stability issues, engine load may be increased above the demanded load and the excess power used to charge a system battery, or if the battery state of charge is above a threshold, the engine may be shut down and the vehicle propelled via battery power. In this way, fuel economy and combustion stability issues may be improved, NOx emissions reduced, and costs for implementation of dedicated exhaust gas recirculation decreased.

Claims

1. A method comprising:

recirculating exhaust gases from one or more cylinders of an engine to remaining cylinders without controlling the amount of the recirculated exhaust gases;

controlling power output of the engine to a desired power; and

under light loads of the engine, increasing the power beyond the desired power, and recharging an onboard energy storage device to reduce the power to the desired power while maintaining the amount of recirculated exhaust gases.

2. The method of claim 1, wherein the desired power comprises a desired wheel power or a desired engine idle speed;

and

wherein the onboard energy storage device comprises one or more of a battery, a mechanical flywheel storage device, or a hydraulic pressure accumulator.

3. The method of claim 1, wherein light loads of the engine comprise a torque demand below an engine output torque threshold where recirculating exhaust gases from one or more cylinders of the engine to the remaining cylinders without controlling the amount of the recirculated exhaust gases results in combustion instability;

wherein the engine output torque threshold is greater than a tip-out event torque level by a predetermined amount;

wherein light loads further comprise torque demand lower than the engine output torque threshold, but greater than the tip-out event torque level; and

where a tip-out event includes one or more of braking of a vehicle, lifting off of a gas pedal of the vehicle, or a combination of braking and lifting off of the gas pedal.

4. The method of claim 3, further comprising:

responsive to light loads of the engine and an energy storage capacity of the energy storage device greater than a predetermined amount, or responsive to a tip-out event;

stopping fuel injection to the one or more engine cylinders that recirculate exhaust gas to an intake manifold of the engine and the remaining cylinders, and stopping fuel injection to the remaining cylinders; and

propelling the vehicle via energy from the energy storage device;

wherein the energy storage capacity of the energy storage device greater than the predetermined amount comprises a level of storage capacity where the energy storage device is unable to accept further energy storage.

5. The method of claim 4, wherein stopping fuel injection to the one or more engine cylinders that recirculate exhaust gas to the intake manifold and the remaining engine cylinders, and stopping fuel injection to the remaining engine cylinders further comprises:

operating the energy storage device to spin the engine unfueled to purge the intake manifold of residual exhaust and replenish the intake manifold with fresh intake air;

where air supplied to the intake manifold is regulated by an intake throttle, and wherein the intake throttle is commanded open during spinning the engine unfueled; and

responsive to an indication that residual exhaust in the intake manifold is below a threshold level;

spinning the engine to rest via the onboard energy storage device.

6. The method of claim 4, wherein stopping fuel injection to the one or more engine cylinders that recirculate exhaust gas to the intake manifold and the remaining engine cylinders, and stopping fuel injection to the remaining engine cylinders further comprises:

indicating that engine operation is not required;

wherein engine operation being required comprises a request for vehicle cabin heat, or vehicle cabin air-conditioning.

7. The method of claim 6, wherein responsive to an indication that engine operation is required during either light loads of the engine where the energy storage capacity of the energy storage device is greater than the predetermined amount, or a tip-out event:

stopping fuel injection to the one or more engine cylinders that recirculate exhaust gas to the remaining engine cylinders such that the one or more engine cylinders that recirculate exhaust gas to the remaining cylinders are operated with air;

operating the onboard energy storage device to increase engine speed to a predetermined threshold engine speed; and

operating the onboard energy storage device to cancel torque pulsations resulting from an imbalance between torque produced from combusting and non-combusting cylinders;

where cancelling torque pulsations includes supplying torque to a driveline of the vehicle, to provide a substantially similar level of torque as previous and/or subsequent combusting cylinders.

8. The method of claim 5, further comprising subsequent to spinning the engine to rest and responsive to an engine restart event:

indicating whether the restart event comprises a cold start event, where a cold start event comprises an engine temperature or engine coolant temperature below a threshold temperature.

9. The method of claim 8, wherein responsive to an indication that the engine restart event does not comprise a cold start event:

concurrently starting fuel injection to both the remaining engine cylinders that do not recirculate exhaust gas to the intake manifold and to the one or more engine cylinders that recirculate exhaust gas to the intake manifold; and

increasing engine torque to at least the engine output torque threshold, and recharging the energy storage device;

where the energy storage capacity of the energy storage device is indicated to be less than the predetermined amount.

10. The method of claim 8, wherein responsive to an indication that the engine restart event does not comprise a cold start event:

activating the engine by starting fuel injection to the remaining engine cylinders that do not recirculate exhaust gas to the intake manifold, and not starting fuel injection to the one or more engine cylinders that recirculate exhaust gas to the intake manifold;

monitoring an engine speed; and

responsive to the engine speed reaching a threshold engine speed, where a rate of change in engine speed is further indicated to be less than a threshold rate of change;

maintaining activated the remaining engine cylinders that do not recirculate exhaust gas to the intake manifold, and starting fuel injection to the one or more engine cylinders that recirculate exhaust gas to the intake manifold;

where starting fuel injection to the one or more engine cylinders that recirculate exhaust gas to the intake manifold further comprises an indication of engine torque demand greater than the engine output torque threshold.

11. The method of claim 8, wherein responsive to an indication that the engine restart event comprises a cold start event:

activating the engine by starting fuel injection to the remaining engine cylinders that do not recirculate exhaust gas to the intake manifold, and not starting fuel injection to engine cylinders that recirculate exhaust gas to the intake manifold;

monitoring an engine speed; and

responsive to the engine speed reaching a threshold engine speed, where a rate of change in engine speed is further indicated to be less than a threshold rate of change, and where the energy storage capacity of the energy storage device is indicated to be less than the predetermined amount;

increasing engine torque to at least the engine output torque threshold, recharging the onboard energy storage device; and

starting fuel injection to engine cylinders that recirculate exhaust gas to the intake manifold.

12. The method of claim 11, further comprising:

responsive to an indication that a desired engine torque is equal to or greater than the engine output torque threshold;

maintaining activated the remaining engine cylinders that do not recirculate exhaust gas to the intake manifold and maintaining activated the engine cylinders that recirculate exhaust gas to the intake manifold; and

operating the engine at the desired engine torque.

13. A method comprising:

recirculating exhaust gases from one or more cylinders of an engine to an intake manifold of the engine and to remaining cylinders without controlling an amount of the recirculated exhaust gases;

controlling power output of the engine to a desired power to propel a motor vehicle driven by the engine at a desired speed; and

when engine loads are less than a preselected load and when a charge state of an energy storage device is less than a predetermined amount, increasing the power beyond the desired power, and recharging the energy storage device to reduce the power to the desired power while maintaining the amount of recirculated exhaust gases, the energy storage device comprising one or more of a battery, a mechanical flywheel storage device, or a hydraulic pressure accumulator; and

when engine loads are less than the preselected load and when charge state of the energy storage device is greater than the predetermined amount, propelling the vehicle at least in part by energy from the energy storage device.

14. The method of claim 13, further comprising stopping fueling of at least the one or more engine cylinders that recirculate exhaust gas to the remaining cylinders when engine loads are less than the preselected load and when charge state of the energy storage device is greater than the predetermined amount.

15. The method of claim 14, further comprising ceasing the vehicle propulsion from the energy storage device and resuming fueling the one or more cylinders that recirculate exhaust gas to the remaining cylinders when the charge state of the energy storage device exceeds a predetermined value.

16. The method of claim 13, wherein engine loads below the preselected load during recirculating exhaust gases from one or more cylinders of the engine to the remaining cylinders results in combustion instability;

wherein the preselected load is greater than a tip-out event load by a predetermined amount, a tip-out event comprising one or more of braking of the vehicle, lifting off of a gas pedal of the vehicle, or a combination of braking and lifting off of the gas pedal; and

wherein a tip-out event comprises shutting off at least the one or more cylinders that recirculate exhaust gas to the remaining cylinders and propelling the vehicle at least in part by energy from the energy storage device, independent of whether the charge state of the energy storage device is greater than, or less than, the predetermined amount.

17. The method of claim 16, further comprising:

indicating whether engine operation is required, wherein required engine operation comprises a request for vehicle cabin heat, or air-conditioning;

under conditions wherein the charge state of the energy storage device is greater than the predetermined amount and engine load is below the preselected load but greater than a tip-out event, or responsive to a tip-out event independent of the charge state of the energy storage device;

shutting off the one or more cylinders that recirculate exhaust gas to the remaining cylinders and shutting off the remaining cylinders, and propelling the vehicle wholly by energy from the energy storage device;

where engine operation is not indicated to be required.

18. The method of claim 17, further comprising:

wherein engine operation is indicated to be required; and

responsive to conditions wherein the charge state of the energy storage device is greater than the predetermined amount and engine load is below the preselected load but greater than a tip-out event, or responsive to a tip-out event independent of the charge state of the energy storage device;

stopping fuel injection to the one or more engine cylinders that recirculate exhaust gas to the remaining engine cylinders such that the one or more engine cylinders that recirculate exhaust gas to the remaining cylinders are operated with air;

operating the energy storage device to increase engine speed to a predetermined threshold engine speed; and

operating the energy storage device to cancel torque pulsations resulting from an imbalance between torque produced from combusting and non-combusting cylinders;

where cancelling torque pulsations includes supplying torque to a driveline of the vehicle, to provide a substantially similar level of torque as previous and/or subsequent combusting cylinders.

19. The method of claim 17, wherein shutting off the one or more cylinders that recirculate exhaust gas to the remaining cylinders and shutting off the remaining cylinders, and propelling the vehicle wholly by energy from the energy storage device further comprises:

operating the energy storage device to spin the engine unfueled to purge the intake manifold of residual exhaust and replenish the intake manifold with fresh intake air;

where air supplied to the intake manifold is regulated by an intake throttle, and wherein the intake throttle is commanded open during spinning the engine unfueled; and

responsive to an indication that residual exhaust in the intake manifold is below a threshold level;

spinning the engine to rest via the energy storage device.

20. A hybrid vehicle system, comprising:

an engine including an intake passage and an exhaust passage;

an energy storage device;

vehicle wheels propelled using torque from one or more of the engine and energy from the energy storage device;

a first set of one or more cylinders that route exhaust to an exhaust passage;

a second set of one or more cylinders that route exhaust directly from the second set of cylinder(s) to an intake manifold of the engine;

a controller, storing instructions in non-transitory memory, that when executed, cause the controller to;

control power output of the engine to a desired power to propel the vehicle driven by the engine at a desired speed, and when engine loads are less than a preselected load and when a charge state of the energy storage device is less than a predetermined amount, increase the power beyond the desired power, and charge the energy storage device to reduce the power to the desired power; and

when engine loads are less than the preselected load and when charge state of the energy storage device is greater than the predetermined amount, stop fueling at least the one or more cylinders that route exhaust gas to the intake manifold and propelling the vehicle at least in part by energy from the energy storage device;

wherein the onboard energy storage device comprises one or more of a battery, a mechanical flywheel storage device, or a hydraulic pressure accumulator.