METHODS AND SYSTEMS FOR ENGINE STARTING

• US 20120104767A1
• Filed: 10/27/2010
• Published: 05/03/2012
• Est. Priority Date: 10/27/2010
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Gibson, Alex O'Connor, Gale, Allan Roy, DeMarco, John Anthony, Boscheratto, Vincent John
• Granted Patent: US 8,569,902 B2
• Time in Patent Office: Days
• US Class Current: 290/36.R
• CPC Class Codes: B60L 1/003 to auxiliary motors, e.g. for pumps, compressors
• CPC Class Codes: B60L 15/20 for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/441 Speed
• CPC Class Codes: B60L 2240/445 Temperature
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 58/20 having different nominal voltages
• CPC Class Codes: F02N 11/08 Circuits or control means specially adapted for starting of engines
• CPC Class Codes: F02N 11/0866 comprising several power sources, e.g. battery and capacitor or two batteries
• CPC Class Codes: F02N 11/087 Details of the switching means in starting circuits, e.g. relays or electronic switches
• CPC Class Codes: F02N 2011/0888 DC/DC converters
• CPC Class Codes: F02N 2250/02 Battery voltage drop at start, e.g. drops causing ECU reset
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

A system for improving engine starting is disclosed. In one example, an engine starting is improved by providing a predictable load to the engine during engine starting. The predictable load may be provided by controlling alternator field voltage during the engine start.

Claims

1. An engine starting system, comprising:

an engine;

an engine starter;

a first battery in electrical communication with the engine starter during an engine start; and

an alternator mechanically coupled to the engine, the alternator having a field coil excitation circuit that is electrically buffered from the first battery during an engine start, the field coil excitation circuit in electrical communication with a power source other than the first battery during the engine start.

2. The engine starting system of claim 1, wherein the power source is a second battery.

3. The engine starting system of claim 1, wherein the power source is a DC/DC converter configured to electrically buffer the field coil excitation circuit from the first battery during the engine start.

4. The engine starting system of claim 1, wherein the field coil excitation circuit includes a voltage controller for regulating an alternator field voltage during the engine start.

5. The engine starting system of claim 1, further comprising a controller, the controller including instructions for selectively shutting down the engine during engine idle-stop conditions and selectively restarting the engine during restart conditions.

6. The engine starting system of claim 4, further comprising a switch coupled in parallel to the power source, the field coil excitation circuit electrically buffered from the first battery when the switch is open.

7. The engine starting system of claim 5, wherein the controller includes further instructions for opening the switch during the engine start, and closing the switch after a voltage at an input of the power source exceeds a threshold voltage or after a predetermined amount of time after engine speed reaches a threshold engine speed.

8. The engine starting system of claim 7, further comprising a diode in a circuit that electrically couples the first battery to the field coil excitation circuit, wherein a cathode of the diode is oriented toward the field coil excitation circuit, and wherein an anode of the diode is oriented toward the first battery, the diode electrically buffering the field coil excitation circuit from the first battery via limiting current flow in a direction from the field coil excitation circuit to the first battery.

9. A vehicle system, comprising:

an engine that is selectively shut-down during engine idle-stop conditions;

a battery;

a starter;

a DC/DC converter electrically coupled to the battery, the DC/DC converter configured to provide a regulated voltage output;

an alternator including an alternator field coil excitation circuit, the alternator field coil excitation circuit electrically coupled to an output of the DC/DC converter during an engine start, the alternator mechanically coupled to the engine; and

a controller with computer readable instructions for,

during an engine restart from idle-stop conditions, adjusting engine torque via at least one torque actuator.

10. The vehicle system of claim 9, wherein the starter is powered by the battery during the engine start.

11. The vehicle system of claim 9, wherein an armature of the alternator is in electrical communication with the battery, the battery supplying power to the DC/DC converter, and wherein the alternator field coil excitation circuit is electrically buffered from the battery via the DC/DC converter.

12. The vehicle system of claim 9, wherein an output voltage of the DC/DC converter is greater than a voltage of the battery during engine cranking.

13. The vehicle system of claim 9, further comprising a diode in a circuit that electrically couples the battery to the alternator field coil excitation circuit, a cathode of the diode oriented towards the alternator field coil excitation circuit, and an anode of the diode oriented towards the battery, the diode electrically buffering the alternator field coil excitation circuit from the battery by limiting current flow in a direction from the alternator field coil excitation circuit to the battery.

14. The vehicle system of claim 13, further comprising a switch coupled in parallel with the DC/DC converter, the controller including further instructions for,

during the engine restart, opening the switch to electrically buffer the alternator field coil excitation circuit from the battery;

and

following the engine restart, closing the switch to bypass a buffer circuit between the alternator field coil excitation circuit and the battery.

15. The vehicle system of claim 9, wherein the DC/DC converter is further electrically coupled to one or more auxiliary electrical loads including interior vehicle lighting.

16. The vehicle system of claim 9, further comprising a power steering system electrically coupled to the alternator, the controller including further instructions for controlling a current supplied to the power steering system by the alternator during the engine start.

17. A method of controlling a vehicle system including an engine that is selectively shut-down during engine idle-stop conditions, comprising:

during an engine start,

electrically buffering an alternator field coil excitation circuit of an alternator from a battery supplying power to a starter; and

maintaining an alternator field coil excitation circuit input voltage to control a load applied to the engine via an alternator rotor.

18. The method of claim 17, further comprising, bypassing the electrical buffering of the field coil excitation circuit of the alternator after a voltage at the battery is greater than a threshold voltage.

19. The method of claim 18, wherein maintaining the alternator field coil excitation circuit input voltage includes maintaining the alternator field coil excitation input voltage via a DC/DC converter.

20. The method of claim 17, wherein the electrical buffering is via a switch.