Cylinder firing fraction determination and control systems and methods

• US 9,441,550 B2
• Filed: 06/10/2014
• Issued: 09/13/2016
• Est. Priority Date: 06/10/2014
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company), Tula Technology, Incorporated
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Li, Jinbiao, Liu, Haifeng
• Primary Examiner(s): Burgess, Ramya
• Assistant Examiner(s): HANNON, TIMOTHY
• Application Number:
  US14/300,469
• Publication Number:
  US 20150354470A1
• Time in Patent Office: 826 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: B60W 10/023 Fluid clutches
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/10 including control of change-speed gearings
• CPC Class Codes: B60W 30/1882 characterised by the working point of the engine, e.g. by using engine output chart
• CPC Class Codes: F02D 17/02 Cutting-out cutting-out engines in multiple engine arrangements F02D25/04
• CPC Class Codes: F02D 2200/0625 Fuel consumption, e.g. measured in fuel liters per 100 kms or miles per gallon
• 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 41/0215 in relation with elements of the transmission
• CPC Class Codes: F02D 41/1406 with use of a optimisation method, e.g. iteration

Abstract

A selection module selects a gear ratio for a transmission, a turbine speed for a torque converter, and a torque request for an engine. A fueling determination module determines a first fueling rate based on a first cylinder firing fraction, the torque request, and an engine speed and determines a second fueling rate based on a second cylinder firing fraction, the torque request, and the engine speed. A mapping module selects one of the first and second cylinder firing fractions based on a comparison of the first and second fueling rates and stores the selected one of the first and second cylinder firing fractions in an entry of a mapping corresponding to the gear ratio, the turbine speed, and the torque request.

Claims

1. An engine control system comprising:

a selection module that selects a gear ratio for a transmission, a turbine speed for a torque converter, and a first torque request for an engine;

a fueling determination module that determines a first fueling rate as a function of a first cylinder firing fraction, the first torque request, and an engine speed and that determines a second fueling rate as a function of a second cylinder firing fraction, the first torque request, and the engine speed;

a mapping module that selects one of the first and second cylinder firing fractions based on a comparison of the first and second fueling rates and that stores the selected one of the first and second cylinder firing fractions in an entry of a mapping corresponding to the gear ratio, the turbine speed, and the first torque request;

a torque request module that generates a second torque request based on at least one driver input; and

a cylinder control module that determines a target cylinder firing fraction based on the second torque request and using the mapping and that controls activation and deactivation of cylinders of the engine based on the target firing fraction.

2. The engine control system of claim 1 wherein the mapping module selects the first cylinder firing fraction when the first fueling rate is less than the second fueling rate and selects the second cylinder firing fraction when the second fueling rate is less than the first fueling rate.

3. The engine control system of claim 1 wherein:

the fueling determination module determines a third fueling rate as a function of a third cylinder firing fraction, the first torque request, and the engine speed; and

the mapping module selects one of the first, second, and third cylinder firing fractions based on a comparison of the first, second, and third fueling rates and stores the selected one of the first, second, and third cylinder firing fractions in the entry of the mapping corresponding to the gear ratio, the turbine speed, and the first torque request.

4. The engine control system of claim 1 wherein:

the selection module further selects a second gear ratio for the transmission, a second turbine speed for the torque converter, and a third torque request for the engine;

the fueling determination module determines a third fueling rate as a function of the first cylinder firing fraction, the third torque request, and a second engine speed and determines a fourth fueling rate as a function of the second cylinder firing fraction, the third torque request, and the second engine speed; and

the mapping module selects one of the first and second cylinder firing fractions based on a comparison of the third and fourth fueling rates and stores the selected one of the first and second cylinder firing fractions in a second entry of the mapping corresponding to the second gear ratio, the second turbine speed, and the third torque request.

5. The engine control system of claim 1 further comprising an engine speed module that determines the engine speed based on the turbine speed and a state of a torque converter clutch.

6. The engine control system of claim 5 wherein, when the torque converter clutch is disengaged, the engine speed module determines the engine speed based on the first torque request, a k-factor of the torque converter, and the turbine speed.

7. The engine control system of claim 5 wherein, when the torque converter clutch is engaged, the engine speed module determines the engine speed based on the turbine speed and a torque converter clutch slip.

8. The engine control system of claim 7 further comprising a slip limit module that determines a maximum torque converter clutch slip,

wherein the mapping module prevents the selection of the first cylinder firing fraction when the torque converter clutch slip is greater than the maximum torque converter clutch slip.

9. The engine control system of claim 1 further comprising a torque limit module that determines a maximum torque output of the engine based on the first cylinder firing fraction, the gear ratio, and the engine speed,

wherein the mapping module prevents the selection of the first cylinder firing fraction when the maximum torque output of the engine is less than the first torque request.

10. An engine control method for a vehicle comprising:

selecting a gear ratio for a transmission, a turbine speed for a torque converter, and a first torque request for an engine;

determining a first fueling rate as a function of a first cylinder firing fraction, the first torque request, and an engine speed;

determining a second fueling rate as a function of a second cylinder firing fraction, the first torque request, and the engine speed;

selecting one of the first and second cylinder firing fractions based on a comparison of the first and second fueling rates;

storing the selected one of the first and second cylinder firing fractions in an entry of a mapping corresponding to the gear ratio, the turbine speed, and the first torque request;

generating a second torque request based on at least one driver input;

determining a target cylinder firing fraction based on the second torque request and using the mapping; and

controlling activation and deactivation of cylinders of the engine based on the target firing fraction.

11. The engine control method of claim 10 further comprising:

selecting the first cylinder firing fraction when the first fueling rate is less than the second fueling rate; and

selecting the second cylinder firing fraction when the second fueling rate is less than the first fueling rate.

12. The engine control method of claim 10 further comprising:

determining a third fueling rate as a function of a third cylinder firing fraction, the first torque request, and the engine speed;

selecting one of the first, second, and third cylinder firing fractions based on a comparison of the first, second, and third fueling rates; and

storing the selected one of the first, second, and third cylinder firing fractions in the entry of the mapping corresponding to the gear ratio, the turbine speed, and the first torque request.

13. The engine control method of claim 10 further comprising:

selecting a second gear ratio for the transmission, a second turbine speed for the torque converter, and a third torque request for the engine;

determining a third fueling rate as a function of the first cylinder firing fraction, the third torque request, and a second engine speed;

determining a fourth fueling rate as a function of the second cylinder firing fraction, the third torque request, and the second engine speed;

selecting one of the first and second cylinder firing fractions based on a comparison of the third and fourth fueling rates; and

storing the selected one of the first and second cylinder firing fractions in a second entry of the mapping corresponding to the second gear ratio, the second turbine speed, and the third torque request.

14. The engine control method of claim 10 further comprising determining the engine speed based on the turbine speed and a state of a torque converter clutch.

15. The engine control method of claim 14 further comprising, when the torque converter clutch is disengaged, determining the engine speed based on the first torque request, a k-factor of the torque converter, and the turbine speed.

16. The engine control method of claim 14 further comprising, when the torque converter clutch is engaged, determining the engine speed based on the turbine speed and a torque converter clutch slip.

17. The engine control method of claim 16 further comprising:

determining a maximum torque converter clutch slip; and

preventing the selection of the first cylinder firing fraction when the torque converter clutch slip is greater than the maximum torque converter clutch slip.

18. The engine control method of claim 10 further comprising:

determining a maximum torque output of the engine based on the first cylinder firing fraction, the gear ratio, and the engine speed; and

preventing the selection of the first cylinder firing fraction when the maximum torque output of the engine is less than the first torque request.

19. An engine control system comprising:

a selection module that selects a gear ratio for a transmission, a turbine speed for a torque converter, and a first torque request for an engine;

a fueling determination module that determines a first fueling rate based on a first cylinder firing fraction, the first torque request, and an engine speed and that determines a second fueling rate based on a second cylinder firing fraction, the first torque request, and the engine speed;

a mapping module that selects one of the first and second cylinder firing fractions based on a comparison of the first and second fueling rates and that stores the selected one of the first and second cylinder firing fractions in an entry of a mapping corresponding to the gear ratio, the turbine speed, and the first torque request;

a torque request module that generates a second torque request based on at least one driver input; and

a cylinder control module that determines a target cylinder firing fraction based on the second torque request and using the mapping and that controls activation and deactivation of cylinders of the engine based on the target firing fraction,

a slip limit module that determines a maximum torque converter clutch slip,

wherein the mapping module prevents the selection of the first cylinder firing fraction when a torque converter clutch slip is greater than the maximum torque converter clutch slip.