Optimizing combustion recipes to improve engine performance and emissions for variable displacement engines

Patent metadata

Field	Value
Publication number	US-11619187-B2
Application number	US-202217714880-A
Country	US
Kind code	B2
Filing date	Apr 6, 2022
Priority date	Dec 11, 2020
Publication date	Apr 4, 2023
Grant date	Apr 4, 2023

Abstract

A system and method for transitioning a firing fraction of a variable displacement internal combustion engine when generating a desired torque output. During and following the transition to the second firing fraction, a combustion recipe is ascertained and used operating the cylinders of the variable displacement internal combustion engine to generate the desired torque output. The recipe is preferably optimized for the engine operating at the second firing fraction, at least relative to the previous charge of the previous combustion recipe used with the first firing fraction.

First claim

What is claimed is:

1. A method of operating an Internal Combustion Engine (ICE), the method comprising:
operating the ICE at a first firing fraction and a first combustion recipe during a first-time interval and operating the ICE at a second firing fraction and a second combustion recipe during a second time interval after the first-time interval; and
operating the ICE to generate a same output torque during both the first-time interval using the first firing fraction and first combustion recipe and the second time interval using the second firing fraction and the second combustion recipe.

2. The method of claim 1 , further comprising operating one or more cylinders of the ICE as an Air Spring (AS) during one or more skipped working cycles when operating at either the first firing fraction or the second firing fraction.

3. The method of claim 1 , further comprising operating one or more cylinders of the ICE as a Low-Pressure Exhaust Spring (LPES) during one or more skipped working cycles when operating at either the first firing fraction or the second firing fraction.

4. The method of claim 1 , further comprising operating one or more cylinders of the ICE as a High-Pressure Exhaust (HPES) during one or more skipped working cycles when operating at either the first firing fraction or the second firing fraction.

5. The method of claim 1 , wherein operation of the ICE using the second firing fraction and the second combustion recipe results in a change of one or more operational parameter(s) relative to operating the ICE at the first firing fraction and the first combustion recipe.

6. The method of claim 5 , wherein the one or more operational parameter(s) include:
(a) reduced fuel consumption of the ICE;
(b) improved performance of the ICE;
(c) temperature control of an aftertreatment system fluidly coupled to the ICE; or
(d) reduced emissions from the aftertreatment system.

7. The method of claim 1 , further comprising adjusting fuel injection parameters while operating cylinders of the ICE using the second firing fraction and second combustion recipe relative to operating the ICE using the first firing fraction and the first combustion recipe, the adjustment of the fuel injection parameters including one of the following:
(a) adjusting a start time of fuel injection;
(b) using a different number of pulses of fuel; or
(c) a combination of both (a) and (b).

8. The method of claim 1 , further comprising:
ascertaining a number of cylinder recharging events expected to occur during at least a portion of the second time interval the ICE is operating at the second firing and using the second combustion recipe while generating the same torque as during the first time interval while operating at the first firing fraction using the first combustion recipe, wherein each of the ascertained number of cylinder recharging events involves inducting a charge into a chamber of a cylinder, while no combustion occurs, during a skipped firing event;
adjusting at least one component of the second combustion recipe to compensate for the ascertained number of cylinder recharging events; and
operating the ICE to generate the same output torque using the second firing fraction and the second combustion recipe with the at least one component adjusted to compensate for the number of cylinder recharging events.

9. The method of claim 8 , wherein the adjustment of the at least one component of the second combustion recipe further comprises increasing a charge volume of the second combustion recipe to compensate for the ascertained number of cylinder recharging events.

10. The method of claim 1 , further comprising periodically recharging cylinders of the ICE operating as a pneumatic gas spring and adjusting a charge provided to one or more of the cylinders of the ICE to compensate for one or more additional induction events associated with the periodic recharging of the cylinders.

11. The method of claim 1 , wherein the first combustion recipe and the second combustion recipe each include one of the following:
(a) fresh air;
(b) Exhaust Gas Recirculation (EGR);
(c) compression of the fresh air;
(d) cooling of the fresh air; or
(e) any combination of (a) through (d).

12. The method of claim 1 , wherein the second combustion recipe further comprises adjusting, relative to the first combustion recipe, amounts of one or more of (a) fresh air, (b) EGR, (c) compression of the fresh air, and/or (d) cooling of the fresh air.

13. The method of claim 1 , further comprising adjusting a mass of a second charge of the second combustion recipe relative to a first charge of the first combustion recipe.

14. The method of claim 1 , further comprising adjusting a mass of fresh air included in a second charge of the second combustion recipe relative to a first charge of the first combustion recipe.

15. The method of claim 1 , further comprising adjusting a mass of EGR provided in a second charge of the second combustion recipe relative to a first charge of the first combustion recipe.

16. The method of claim 1 , further comprising adjusting a degree of compressed fresh air provided in a second charge of the second combustion recipe relative to a first charge of the first combustion recipe.

17. The method of claim 1 , further comprising adjusting a degree of cooling of fresh air provided in a second charge of the second combustion recipe relative a first charge of the first combustion recipe.

18. The method of claim 1 , further comprising increasing an oxygen mole fraction of a charge provided to a select cylinder of the ICE for a select firing opportunity, the increased oxygen mole fraction mitigating an ignition delay for the select cylinder caused by a cooling of the select cylinder.

19. The method of claim 1 , further comprising reducing an amount of cooling of a charge provided to select cylinder of the ICE for a select firing opportunity, the reduced amount of cooling of the charge mitigating an ignition delay during the select firing opportunity caused by a cooling of the select cylinder.

20. The method of claim 1 , further comprising increasing compression of a charge provided to a select cylinder of the ICE for a select firing opportunity, the increased compression of the charge resulting in an increased oxygen mole fraction of the charge.

21. The method of claim 1 , further comprising:
reducing an amount of fuel provided to a select cylinder of the ICE that is to be fired if a degree of compressed air in a charge to be provided to the select cylinder is sufficiently low, the reduction of the amount of fuel mitigating an excessive smoke condition; and
reducing an amount of EGR included in a charge provided to a select cylinder of the ICE that is to be fired during a firing opportunity if an amount of compressed air in the charge is too low.

22. The method of claim 1 , wherein the ICE is a variable displacement ICE capable of operating in one or more of the following modes:
(a) a skip fire mode where at least one cylinder is fired, skipped and either fired or skipped over successive working cycles while the ICE is operating at an effective reduced displacement that is less than full displacement of the ICE;
(b) in a dynamic skip fire mode wherein decisions to either fire or skip the cylinders of the ICE are dynamically made either (i) on a firing opportunity-by-firing opportunity basis or (ii) on an engine cycle-by-engine cycle basis;
(c) a fixed firing pattern where a first group of one or mor

Assignees

• Tula Technology Inc
• Cummins Inc

Inventors

• Serrano Louis J
• Cai Xiaoping
• Chen Shikui Kevin
• Wolk Benjamin M
• Brahma Avra
• Lee Justin R

Classifications

• Y02T10/40

  Engine management systems · CPC title

• F02D41/0007

  for control of turbo-charged or super-charged engines (control of the pumps per se F02B37/12) · CPC title

• F02B29/0493

  Controlling the air charge temperature · CPC title

• F02M26/05

  High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor · CPC title

• F02B29/0418

  the intake air cooler having a bypass or multiple flow paths within the heat exchanger to vary the effective heat transfer surface · CPC title