METHODS AND SYSTEMS FOR SELECTIVE ENGINE STARTING

• US 20150083079A1
• Filed: 09/26/2013
• Published: 03/26/2015
• Est. Priority Date: 09/26/2013
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Li, Yonghua, Hashemi, Siamak
• Granted Patent: US 9,631,595 B2
• Time in Patent Office: Days
• US Class Current: 123/350
• CPC Class Codes: F02N 11/08 Circuits or control means specially adapted for starting of engines
• CPC Class Codes: F02N 2200/022 Engine speed
• CPC Class Codes: F02N 2200/023 Engine temperature
• CPC Class Codes: F02N 2200/04 said parameters being related to the starter motor
• CPC Class Codes: F02N 2200/041 Starter speed
• CPC Class Codes: F02N 2200/046 Energy or power necessary for starting
• CPC Class Codes: F02N 2200/06 said parameters being related to the power supply or driving circuits for the starter
• CPC Class Codes: F02N 2200/063 Battery voltage
• CPC Class Codes: F02N 2200/064 Battery temperature
• CPC Class Codes: F02N 2200/122 Atmospheric temperature
• CPC Class Codes: F02N 2300/102 Control of the starter motor speed; Control of the engine speed during cranking
• CPC Class Codes: F02N 2300/104 Control of the starter motor torque
• CPC Class Codes: F02N 2300/2002 using different starting modes, methods, or actuators depending on circumstances, e.g. engine temperature or component wear
• CPC Class Codes: F02N 99/006 Providing a combustible mixture inside the cylinder

Abstract

Systems and methods for starting an engine are described. In one example, engine cranking speed for an engine of a hybrid vehicle is adjusted in response to operating conditions. The engine cranking speed may be reduced when capability of a battery that supplies power to rotate the engine is less than an amount of power to rotate the engine at a higher speed.

Claims

1. A method for starting an engine, comprising:

adjusting an engine cranking speed in response to battery power capability and an amount of power to crank an engine at a desired engine speed; and

cranking the engine at the adjusted cranking speed.

2. The method of claim 1, where engine cranking speed is an engine idle speed.

3. The method of claim 1, where engine cranking speed is a cold start cranking speed.

4. The method of claim 1, where engine cranking speed is lower than a cold start cranking speed.

5. The method of claim 1, where the engine cranking speed is adjusted to an engine idle speed in response to battery power capability being greater than the power to crank the engine at the desired engine speed, and where the desired engine speed is the engine idle speed.

6. The method of claim 1, where the engine cranking speed is adjusted to cold start cranking speed that is less than an engine idle speed in response to battery power capability being greater than the power to crank the engine at the cold start cranking speed and the battery power capability being less than the power to crank the engine at the engine idle speed.

7. The method of claim 1, where the engine cranking speed is adjusted to a speed lower than cold start cranking speed in response to battery power capability being less than the power to crank the engine at the cold start cranking speed.

8. A method for starting an engine, comprising:

adjusting a battery power capability in response to output of a battery cell having a lowest state of charge among a plurality of battery cells in a battery;

adjusting an engine cranking speed in response to the battery power capability and power to crank an engine at a desired engine speed; and

cranking the engine at the adjusted cranking speed.

9. The method of claim 8, where the battery power capability is based on power capability of a plurality of battery cells in a battery.

10. The method of claim 8, where the battery power capability is based on a state of charge of the battery cell, a temperature reading of the battery cell, and an pre-determined battery internal resistance as a function of battery cell temperature and SOC, and the ratio of cell crank potential and the battery internal resistance.

11. The method of claim 8, further comprising comparing a result of multiplying the battery power capability by efficiency of a motor rotating the engine with the power to crank the engine at the desired engine speed.

12. The method of claim 8, where power to crank the engine is estimated from engine temperature.

13. The method of claim 12, further comprising adjusting the power to crank the engine based on the engine cranking speed.

14. The method of claim 8, where the engine is cranked via a driveline integrated starter generator.

15. A vehicle system, comprising:

an electric machine;

an engine in mechanical communication with the electric machine; and

a controller including non-transitory instructions executable by a processor to crank the engine via the electric machine and adjust engine speed in response to battery state of charge and a plurality of predetermined engine cranking speeds.

16. The vehicle system of claim 15, where the plurality of predetermined engine cranking speeds include an engine idle speed, a cold start cranking speed, and a lower cranking speed.

17. The vehicle system of claim 16, where the cold start cranking speed is less than the engine idle speed, and where the lower cranking speed is less than the cold start cranking speed.

18. The vehicle system of claim 15, further comprising additional instructions for adjusting engine speed to the engine idle speed in response to battery power capability being greater than the power to crank the engine at the engine idle speed.

19. The vehicle system of claim 15, further comprising additional instructions for adjusting engine speed to the engine a cold start cranking speed in response to battery power capability being less than the power to crank the engine at the engine idle speed.

20. The vehicle system of claim 15, further comprising additional instructions to compare a result of multiplying a battery power capability by efficiency of the electric machine at a desired engine speed.