Method and apparatus for determining optimum skip fire firing profile with adjustments for ambient temperature

• US 9,739,212 B1
• Filed: 05/06/2016
• Issued: 08/22/2017
• Est. Priority Date: 05/06/2016
• Status: Active Grant

• Current Assignee: Tula Technology, Incorporated
• Original Assignee: Tula Technology, Incorporated
• Inventors: Srinivasan, Vijay, Serrano, Louis J.
• Primary Examiner(s): Huynh, Hai
• Application Number:
  US15/148,826
• Time in Patent Office: 473 Days
• Field of Search: 123198 F, 123198 DB, 123198 DC, 123481
• CPC Class Codes: F02D 2200/021 Engine temperature
• CPC Class Codes: F02D 2200/501 Vehicle speed
• CPC Class Codes: F02D 2200/702 Road conditions
• CPC Class Codes: F02D 2250/18 Control of the engine output torque
• CPC Class Codes: F02D 41/0087 Selective cylinder activation, i.e. partial cylinder operation deceleration cut-off F02D41/123
• CPC Class Codes: F02D 41/021 Introducing corrections for particular conditions exterior to the engine conjoint control of vehicle sub-units for propelling the vehicle B60W30/18
• CPC Class Codes: F02D 41/0225 in relation with the gear ratio or shift lever position

Abstract

In one aspect, a skip fire engine controller is described. The skip fire engine controller includes a skip fire module arranged to determine an operational firing fraction and associated cylinder load for delivering a desired engine output. The skip fire engine controller also includes a firing controller arranged to direct firings in a skip fire manner that delivers the selected operational firing fraction. Various methods, modules, lookup tables and arrangements related to the selection of a suitable operational firing fraction are also described.

Claims

1. A skip fire engine controller comprising:

a skip fire profile module arranged to determine an operational firing fraction and associated cylinder load for delivering a desired engine output, wherein the operational firing fraction is selected at least in part based on at least one temperature affecting a coupling of noise and vibration to a vehicle cabin at the selected operational firing fraction; and

a firing controller arranged to direct firings in a skip fire manner that delivers the selected operational firing fraction.

2. A skip fire engine controller of claim 1, wherein:

the skip fire profile module is arranged to determine an operational firing fraction and associated cylinder load for delivering a desired engine output, wherein the skip fire profile module is arranged to select the operational firing fraction from a set of available firing fractions, wherein the set of available firing fractions varies as a function of cylinder load such that more firing fractions are available at lower cylinder loads than at higher cylinder load and the firing fraction is selected at least in part based on the at least one temperature affecting noise and vibration coupled to the vehicle cabin at the selected operational firing fraction.

3. The skip fire engine controller of claim 1, wherein the at least one temperature comprises a temperature of a power train mount system used to isolate engine excitations from the vehicle cabin.

4. The skip fire engine controller of claim 1, wherein the skip fire profile module is configured to adjust the operational firing fraction based on a temperature dependence of a stiffness of the set of power train mounts used to isolate engine excitations from the vehicle cabin.

5. The skip fire engine controller of claim 1, wherein the skip fire profile module is configured to adjust the operational firing fraction based on a temperature dependence of a frequency response function of an isolation system used to isolate engine excitations from the vehicle cabin.

6. The skip fire engine controller of claim 5, wherein the skip fire profile module is configured to adjust the operational firing fraction in response to a change in the temperature of the isolation system.

7. The skip fire engine controller of claim 1, wherein the at least one temperature is monitored based on at least one of a thermal sensor input, an engine temperature, and a thermal model.

8. The skip fire engine controller of claim 1, wherein the skip fire profile module is configured to monitor at least one additional temperature related to noise and vibration generated by the engine and utilize the at least one additional temperature to select the firing fraction.

9. The skip fire engine controller of claim 1, wherein the at least one temperature comprises a temperature of a portion of a fit or clearance of a component of a powertrain.

10. The skip fire engine controller of claim 1, wherein the selection of the operational firing fraction is based on at least one table indicative of allowable firing fractions for a set of engine operating parameters and a temperature adjustment of the at least one table is performed.

11. The skip fire engine controller of claim 10, wherein a correction factor to the at least one table is selected based on the at least one temperature.

12. The skip fire engine controller of claim 1, wherein the selection of the operational firing fraction is based on a set of tables for different temperature ranges and a selection is made of at least one table based on the at least one temperature.

13. The skip fire engine controller of claim 12, wherein the selection of the operational firing fraction involves selecting a lookup table, from a plurality of lookup tables, based on the at least one temperature.

14. The skip fire engine controller of claim 1, wherein the skip fire controller is configured to determine a correction to the firing fraction based on a system excitation model of a coupling of engine excitations to the vehicle cabin as a function of the at least one temperature.

15. The skip fire controller of claim 1, wherein the at least one temperature comprises a temperature of an isolation system used to isolate engine excitations from the vehicle cabin and skip fire profile module is configured to monitor the at least one temperature at least once subsequent to engine startup and adjust the selection of the firing fraction to maintain Noise, Vibration, and Harshness below a limit value.

16. The skip fire controller of claim 1, wherein a user may disable selection of the operational firing fraction and associated cylinder load based on the at least one temperature.

17. A skip fire engine controller comprising:

at least one lookup table embodied in a computer readable media, the at least one lookup table including table entries that indicate different maximum allowable cylinder loads at different vehicle operating parameters and provide adjustments based on at least one temperature associated with a temperature response of isolation of engine excitation from a vehicle cabin;

a skip fire profile module arranged to determine an operational firing fraction suitable for delivering a requested engine output, wherein the skip fire profile module utilizes the at least one lookup table to determine the operational firing fraction at the at least one monitored temperature; and

a firing controller arranged to direct firings in a skip fire manner that delivers the operational firing fraction.

18. The skip fire engine controller as recited in claim 17, wherein the at least one monitored temperature comprises a temperature of an isolation mount system.

19. The skip fire engine controller as recited in claim 17, wherein the at least one monitored temperature comprises an engine or powertrain component.

20. A skip fire engine controller as recited in claim 17 wherein:

the firing fraction determination is based at least in part on a base firing fraction;

the skip fire engine controller further comprises a base firing fraction calculator that indicates a base firing fraction that is substantially optimally fuel efficient for a given engine speed and engine output.

21. A method of selecting an operational skip fire firing profile suitable for use in operating an internal combustion engine in a skip fire manner to produce a desired engine output, the method comprising:

determining a desired engine output;

monitoring at least one temperature affecting coupling of noise and vibration from the engine to a vehicle cabin; and

selecting a firing fraction based at least in part on the coupling of noise and vibration to the vehicle cabin at the monitored at least one temperature.

22. The method of claim 21, further comprising:

selecting a plurality of candidate firing fractions from an allowed list of firing fractions;

calculating a candidate cylinder load for each of the plurality of candidate firing fractions such that the combination of the candidate cylinder load and each associated candidate firing fraction substantially yields the desired engine output, each such combination being a candidate skip fire firing profile;

selecting one of the candidate skip fire firing profiles as the operational skip fire firing profile; and

operating the internal combustion engine based at least in part on the operational skip fire firing profile.

23. A method as recited in claim 21 further comprising:

determining which of the candidate skip fire firing profiles is most fuel efficient in delivering the engine output wherein the selection of the operational skip fire firing profile is based on the fuel efficiency determination.

24. A method as recited in claim 21 wherein:

the plurality of candidate firing fractions includes a first and a second candidate firing fraction;

calculating a first candidate cylinder load such that a combination of the first candidate firing fraction and the first candidate cylinder load delivers the desired engine output and forms a first candidate skip fire firing profile; and

determining whether the first candidate skip fire firing profile is allowed wherein the allowance of the first candidate skip fire firing profile depends in part on whether the first candidate cylinder load exceeds a threshold wherein the threshold varies as a function of engine speed and transmission gear.

25. The method of claim 24, wherein the at least one temperature comprises a temperature of a mounting system associated with isolating engine excitations from the vehicle cabin.

26. The method of claim 25, wherein the mounting system has a temperature-dependent isolation response.

27. The method of claim 21, wherein the firing fraction is adapted at least once in response to detecting a change in the at least one temperature during operation of the engine.

28. The method of claim 21, wherein the mounting system has a frequency response function that varies with temperature and the firing fraction is adapted at least in part based on the excitation frequencies of the engine and the natural frequencies of the mounting system.