Methods of operating a series hybrid vehicle

• US 20050145426A1
• Filed: 02/14/2005
• Published: 07/07/2005
• Est. Priority Date: 09/25/2003
• Status: Active Grant

• Current Assignee: GOV of The USA As Represented By The Administrator of The US Environmental Protection, The Agency
• Original Assignee: GOV of The USA As Represented By The Administrator of The US Environmental Protection, The Agency
• Inventors: Gray, Charles L. Jr.
• Granted Patent: US 7,857,082 B2
• Time in Patent Office: Days
• US Class Current: 180/65.245
• CPC Class Codes: B60K 5/08 comprising more than one engine
• CPC Class Codes: B60K 6/46 Series type
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 50/61 by batteries charged by engine-driven generators, e.g. series hybrid electric vehicles
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/26 for electrical energy, e.g. batteries or capacitors
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/13 in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• 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

Abstract

The invention is directed toward methods for operating a series hybrid vehicle in a manner that responds to the operator'"'"'s demand for power output, while maximizing engine efficiency and minimizing disruptions in vehicle drivability. According to principles of the present invention, when the driver of a series hybrid vehicle makes a demand for power output, whether the secondary power source(s) is supplied with secondary energy stored in an energy storage device(s), direct input energy generated by an engine(s), or both, depends on the amount of available secondary energy stored in the vehicle'"'"'s secondary storage device(s) alone, and in combination with vehicle speed. During the time that the engine is used to generate secondary energy, the power efficiency level at which the engine is operated also depends on the vehicle speed and the amount of available secondary energy stored in the vehicle'"'"'s secondary storage device alone, and in combination with vehicle speed. Further, in some embodiments, when the engine is not generating secondary energy, the engine is selectively turned off or idled in response to various operating conditions.

Claims

1. A method of operating a series hybrid vehicle having a primary power source and a secondary power source, the method comprising:

selectively generating an amount of primary power from the primary power source;

converting a first portion of the amount of primary power from the primary power source into an amount of direct input energy;

powering the secondary power source directly with the amount of direct input energy;

monitoring an amount of available stored energy within an energy storage device;

generating the amount of primary power from the primary power source when the amount of available stored energy is below a first selected level;

operating an engine at one of a plurality of preselected power levels to generate the amount of primary power; and

selecting the one of the plurality of preselected power levels based on the amount of available stored energy.

2. The method according to claim 1, further comprising:

turning the engine off when the amount of available stored energy is above the first selected level.

3. The method according to claim 1, further comprising:

idling the engine when the amount of available stored energy is above the first selected level.

4. The method according to claim 1, further comprising:

idling the engine when the amount of available stored energy is above the first selected level; and

turning the engine off when the amount of available stored energy is above the first selected level and a command to decelerate the vehicle is issued.

5. The method according to claim 1 wherein the plurality of preselected power levels includes a predefined minimum power level for efficient operation of the engine, and the engine is operated at or near the predefined minimum power level when the amount of available stored energy is within a predetermined range of available stored energy.

6. The method according to claim 1 wherein the plurality of preselected power levels includes a predefined maximum power level for efficient operation of the engine, and the engine is operated at or near the predefined maximum power level when the amount of available stored energy is within a predetermined range of available stored energy.

7. The method according to claim 6 wherein the predetermined range of available stored energy comprises a range at or near complete depletion of the available stored energy.

8. The method according to claim 1 wherein a number of the plurality of preselected power levels reside within a predefined range of power levels for efficient operation of the engine, and the one of the plurality of preselected power levels is within the predefined range of power levels when the amount of available stored energy is within a predetermined range of available stored energy.

9. The method according to claim 8 wherein the one of the plurality of preselected power levels correlates directionally to the power demanded by the vehicle driver.

10. The method according to claim 8 wherein the one of the plurality of preselected power levels is about inversely proportional to the amount of available stored energy within the predetermined range.

11. The method according to claim 1 wherein the engine is comprised of a first and a second engine, the first selected level of available stored energy is higher than each of a second and a third selected level of available stored energy, and the second selected level is higher than the third selected level, the method further comprising:

operating the first engine when the amount of available stored energy is below the first selected level; and

operating the second engine when the amount of available stored energy is either

     1) below a second selected level and a command to power the vehicle exceeds a predetermined level of power demand, or

     2) when the amount of available stored energy is below the third selected level.

12. The method according to claim 11 wherein when the second engine is operated, the one of the plurality of preselected power levels for the first engine is at or near a predefined maximum power level for efficient operation of the first engine and the one of the plurality of preselected power levels for the second engine is at or near one of 1) a power level within a predefined range of power levels that is inversely proportional to the amount of available stored energy within a predetermined range of available stored energy and 2) a predefined maximum power level for efficient operation of the second engine.

13. The method according to claim 1 wherein the primary power source is comprised of a variable displacement engine, the variable displacement engine having a first number of cylinders defining the first engine and a second number of cylinders defining the second engine.

14. The method according to claim 1 wherein the primary power source is either 1) an internal combustion engine, or 2) a Stirling engine.

15. The method according to claim 1, further comprising:

based on the amount of available stored energy, selectively powering the secondary power source with either

     1) a portion of the amount of available stored energy,

     2) a portion of an amount of direct input energy, or

     3) a combination of the portion of the amount of available stored energy and the portion of the amount of direct input energy.

16. The method according to claim 15, further comprising:

powering the secondary power source with the portion of the amount of available stored energy, instead of the portion of the amount of direct input energy, when the available stored energy is above the first selected level.

17. The method according to claim 15, further comprising:

powering the secondary power source with the portion of the amount of direct input energy, instead of the portion of the amount of available stored energy, when the available stored energy is either

     1) below the first selected level and the amount of direct input energy is sufficient enough to meet a power demand, or

     2) below a second selected level.

18. The method according to claim 15, further comprising:

powering the secondary power source with the combination of the portion of the amount of available stored energy and the portion of the amount of direct input energy when the available stored energy is either

     1) below the first selected level and above a second selected level, and the amount of direct input energy is not sufficient enough to meet a power demand, or

     2) above the second selected level.

19. The method according to claim 1 wherein the primary power source can provide at least 60% to 70% of the desired peak acceleration power level for the vehicle.

20. The method according to claim 1 wherein the energy storage device can efficiently sustain a charge rate matching at least 20% to 25% of the primary power source'"'"'s maximum rated horsepower.

21. The method according to claim 1 wherein the secondary power source is either 1) an electric motor, or 2) a hydraulic motor.

22. A method of powering a secondary power source in a series hybrid vehicle, the method comprising:

monitoring an amount of available stored energy within an energy storage device;

monitoring vehicle speed; and

based on the amount of available stored energy at a given vehicle speed, selectively powering the secondary power source with either

     1) a portion of the amount of available stored energy,

     2) a portion of an amount of direct input energy, or

     3) a combination of the portion of the amount of available stored energy and the portion of the amount of direct input energy.