System and methods for improving fuel economy

Patent metadata

Field	Value
Publication number	US-9925974-B2
Application number	US-201615139146-A
Country	US
Kind code	B2
Filing date	Apr 26, 2016
Priority date	Apr 26, 2016
Publication date	Mar 27, 2018
Grant date	Mar 27, 2018

Abstract

Methods and systems are provided for controlling hybrid vehicle engine operation, where the vehicle engine comprises one or more cylinders dedicated to recirculating exhaust to an intake manifold. In one example, during an engine cold-start event or other event where temperature of one or more exhaust catalysts are below a temperature needed for catalytic activity, fuel injection to the dedicated exhaust gas recirculation cylinder(s) is maintained shut off, while its intake and exhaust valves are maintained activated, thus enabling the dedicated exhaust gas recirculation cylinder(s) to route air to the intake manifold of the engine, resulting in exhaust gas lean of stoichiometry that may serve to heat the catalyst. In this way, during cold start events and other events where temperature of one or more exhaust catalysts are below a temperature for catalytic activity, combustion stability issues may be avoided, and exhaust catalyst(s) rapidly heated, thereby reducing undesired tailpipe emissions.

First claim

The invention claimed is:

1. A method, comprising:
coupling an exhaust from one or more cylinders of a multiple cylinder combustion engine to an intake manifold of the engine; and
during starting and warm-up of the engine under a first set of operating conditions, shutting off fuel and spark to the one or more cylinders while maintaining intake and exhaust valves activated on the one or more cylinders.

2. The method of claim 1 , wherein the first set of operating conditions are related to temperature of one or more exhaust catalysts being below a temperature needed for catalytic activity.

3. The method of claim 2 , wherein the temperature is determined from one or more of the following: a direct temperature measurement of the one or more catalyst(s); temperature of a coolant coupled to the engine; time since the engine was last running; a determination of exhaust temperature based on engine running conditions such as load, speed, air/fuel ratio, and/or spark timing.

4. The method of claim 2 , wherein starting and warming up the engine under the first set of operating conditions by shutting off fuel and spark to the one or more cylinders while maintaining intake and exhaust valves activated on the one or more cylinders decreases a light-off time of the one or more exhaust catalysts, wherein light-off includes the one or more catalysts being above the temperature needed for catalytic activity.

5. The method of claim 1 , further comprising retarding ignition of the engine during starting and warm-up of the engine under the first set of operating conditions.

6. The method of claim 1 , wherein operating the one or more cylinders with intake and exhaust valves activated while fuel is shut off routes air instead of exhaust to the intake manifold of the engine, and spark timing and fuel injection to the remaining cylinders is adjusted to account for said air instead of exhaust.

7. The method of claim 1 , further comprising supplying fuel and spark to the one or more cylinders and to remaining cylinders during starting and of the engine under a second set of operating conditions;
where the remaining cylinders do not couple exhaust to the intake manifold of the engine.

8. The method of claim 7 , wherein the second set of operating conditions comprises one or more of the following: a determination that temperature of one or more exhaust catalyst(s) is at or above a predetermined temperature; time since last engine start being less than a preselected time; an indication exhaust gas temperatures are above a predetermined value; or, temperature of a coolant coupled to the engine being above a threshold value.

9. The method of claim 7 , wherein starting the engine under the second set of operating conditions further comprises:
increasing engine torque to at least an engine output torque threshold, the engine output torque threshold comprising a condition wherein coupling the exhaust from the one or more cylinders to the intake manifold of the engine does not result in combustion instability, and charging an onboard energy storage device when its energy storage capacity is indicated to be less than a predetermined amount; and
wherein the onboard energy storage device comprises one or more of a battery, a mechanical flywheel storage device, or a hydraulic pressure accumulator.

10. The method of claim 9 , further comprising:
responsive to starting the engine under the second set of operating conditions and wherein the energy storage capacity of the energy storage device is indicated to be greater than the predetermined amount;
activating the engine by starting fuel injection and spark to the remaining cylinders, shutting off fuel and spark to the one or more cylinders and not activating intake and exhaust valves on the one or more cylinders;
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 fuel injection to the remaining engine cylinders, and starting fuel injection and spark to the one or more cylinders;
where starting fuel injection and spark to the one or more cylinders that couples exhaust to the intake manifold of the engine further comprises an indication of engine torque demand greater than the engine output torque threshold.

11. A method, comprising:
coupling an exhaust from one or more cylinders of a multiple cylinder combustion engine to an intake manifold of the engine;
in a first condition, including a cold start and warm-up of the engine when temperature of one or more exhaust catalysts is below a predetermined threshold temperature needed for catalytic activity, shutting off fuel and spark to the one or more cylinders while maintaining intake and exhaust valves activated on the one or more cylinders; and
resuming fueling and maintaining activated intake and exhaust valves on the one or more cylinders in a second condition.

12. The method of claim 11 , wherein the second condition comprises an indication that temperature of one or more exhaust catalysts has reached the predetermined threshold temperature.

13. The method of claim 11 , wherein the second condition is related to an indication of engine starting and warm-up.

14. The method of claim 13 , wherein the indication of engine starting comprises an engine speed greater than a threshold speed, and a rate of change of engine speed less than a threshold change rate.

15. The method of claim 11 , further comprising:
in the second condition, responsive to an engine torque below an engine output torque threshold, the engine output torque threshold comprising a condition wherein coupling the exhaust from the one or more cylinders to the intake manifold of the engine does not result in combustion instability:
increasing engine torque to at least the engine output torque threshold, and charging an onboard energy storage device;
wherein an energy storage capacity of the energy storage device is indicated to be less than a predetermined amount;
wherein the onboard energy storage device comprises one or more of a battery, a mechanical flywheel storage device, or a hydraulic pressure accumulator; and wherein
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 and the one or more cylinders and operating the engine at the desired engine torque without charging the onboard storage device;
where the remaining cylinders do not couple exhaust to the intake manifold of the engine.

16. The method of claim 15 , further comprising:
in the second condition, responsive to an engine torque below an engine output torque threshold, and the energy storage capacity of the energy storage device greater than the predetermined amount:
maintaining shutting off fuel and spark to the one or more cylinders and deactivating the intake and exhaust valves on the one or more cylinders, wherein deactivating the intake and exhaust valves comprises configuring both the intake and exhaust valves closed; and
responsive to an indication that the desired engine torque is equal to or greater than the engine output torque threshold:
maintaining activated the remaining engine cylinders, and resuming fueling and spark, and activating intake and exhaust valves on the one or more cylinders.

17. 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

Assignees

• Ford Global Tech Llc

Inventors

• Leone Thomas G
• Miller Kenneth James
• Martin Douglas Raymond

Classifications

• B60K6/28

  characterised by the electric energy storing means, e.g. batteries or capacitors · CPC title

• B60K6/24 Primary

  characterised by the combustion engines · CPC title

• F02D21/08

  the other gas being the exhaust gas of engine · CPC title

• B60W20/13

  in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion · CPC title

• B60K6/48

  Parallel type · CPC title