Hybrid electric vehicle control apparatus for maximizing vehicle engine operating efficiency

• US 6,173,574 B1
• Filed: 07/06/1999
• Issued: 01/16/2001
• Est. Priority Date: 07/07/1998
• Status: Expired due to Term

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Obayashi, Kazuyoshi, Tsuji, Hiroya, Egami, Tsuneyuki
• Primary Examiner(s): NGUYEN, HOANG M
• Application Number:
  US09/348,011
• Time in Patent Office: 560 Days
• Field of Search: 606/98, 607/06, 607/10
• US Class Current: 60/710
• CPC Class Codes: B60K 2006/262 the motor or generator are used as clutch, e.g. between engine and driveshaft
• CPC Class Codes: B60K 6/365 with the gears having orbital motion
• CPC Class Codes: B60K 6/448 Electrical distribution type
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60L 15/2045 for optimising the use of energy
• CPC Class Codes: B60L 2220/52 Clutch motors
• 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 20/15 Control strategies specially adapted for achieving a particular effect
• CPC Class Codes: B60W 2710/0605 Throttle position
• CPC Class Codes: Y02T 10/40 Engine management systems
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• 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
• CPC Class Codes: Y02T 10/84 Data processing systems or methods, management, administration
• CPC Class Codes: Y10S 903/91 : Orbital, e.g. planetary gears

Abstract

A control apparatus for a hybrid electric vehicle that minimizes vehicle fuel-consumption. A fuel consumption coefficient relating to overall efficiency of a hybrid engine is calculated. An engine operating point whereat this fuel-consumption coefficient is optimized is then determined, and the engine is controlled to operate at the determined engine operating point. When such control is performed, overall engine efficiency in all operating regions can be optimized, and further improvements in fuel consumption can be realized.

Claims

1. A control system for a hybrid electric vehicle comprising:

a motive power transmitter comprising a motor to convert at least a portion of engine power to electrical power, and for generating at least a portion of vehicle drive power;

an electricity storage device for transmitting to and receiving from said motor charge and discharge electrical power, respectively;

an operating point determining device for determining an engine operating point of respective portions of said hybrid system including an engine operating point that maximizes overall efficiency based on overall system efficiency-related information extracted from engine input information, as well as a relationship between said overall-efficiency-related information and said engine operating point; and

an operation control device for controlling operation of said hybrid-system based on said determined engine operating point.

2. The control system of claim 1, wherein said engine operating-point determining device calculates said overall-efficiency-related information as a function of efficiency of said engine and efficiency of said motive power transmitter.

3. The control system of claim 1, wherein said operating-point determining device calculates said overall efficiency based on a fuel-consumption quantity of said engine, said charge and discharge electrical power, and a vehicle drive-power requirement value.

4. The control system of claim 3, wherein said operating-point determining device determines said engine operating point so that said overall efficiency is maximized when a total of said vehicle drive-power requirement value, a charge and discharge power requirement value, and loss, coincides with an engine-power requirement value.

5. The control system of claim 1, wherein said operating-point determining device calculates said overall efficiency while shifting said engine operating point by a predetermined amount, and determines said engine operating point so that said overall efficiency is maximized.

6. The control system of claim 1, wherein said operating-point determining device determines a present value of said engine operating point according to shift from a predetermined initial value, and establishes said initial value in a region wherein one of engine efficiency and said overall efficiency is maximized.

7. The control system of claim 1, wherein said operating-point determining device stores a predetermined vehicle operating point, and a previously-determined engine operating point corresponding to said predetermined vehicle operating point, and determines a present engine operating point based on a comparison between said stored predetermined vehicle operating point and a presently-detected vehicle operating point.

8. The control system of claim 1, wherein said operating-point determining device determines said engine operating point solely during a predetermined steady state of operation.

9. The control system of claim 8, wherein said operating-point determining device calculates said overall efficiency while shifting said engine operating point by a predetermined amount, said operating-point determining device shifting said engine operating point from an engine maximum efficiency point so that said overall efficiency is maximized, and performing restriction so that a total shift quantity of said shifted engine operating point does not exceed a predetermined upper-limit value.

10. A hybrid electric vehicle controller comprising:

a device for determining engine operating points of respective engine portions including an engine operating point that maximizes overall efficiency based on overall engine efficiency-related information extracted from engine input information, as well as a relationship between said overall-efficiency-related information and said engine operating point; and

an engine operation control device for controlling engine operation based on said determined engine operating points.

11. The controller of claim 10, wherein said device for determining engine operating points calculates said overall efficiency-related information as a function of engine efficiency and motive power device efficiency.

12. The controller of claim 10, wherein said operating-point determining device calculates said overall efficiency based on an engine fuel-consumption quantity, motive power device charge and discharge electrical power, and a vehicle drive-power requirement value.

13. The controller of claim 12, wherein said operating-point determining device determines said engine operating-point so that said overall efficiency is maximized when a total of a vehicle drive-power requirement value, a charge and discharge power requirement value, and loss, coincides with said engine-power requirement value.

14. The controller of claim 10, wherein said operating-point determining device calculates said overall efficiency while shifting said engine operating point by a predetermined amount, and determines said engine operating point so that said overall efficiency is maximized.

15. The controller of claim 10, wherein said operating-point determining device determines a present engine operating-point according to shift from a predetermined initial value, and establishes said present value in a region wherein one of engine efficiency and overall efficiency is maximized.

16. The controller of claim 10, wherein said operating-point determining device stores a predetermined vehicle operating point, and a predetermined engine operating point corresponding to said stored vehicle operating point, and determines said engine operating point based on a comparison of said stored predetermined vehicle operating point and said present vehicle operating point.

17. The controller of claim 10, wherein said operating-point determining device determines said engine operating point solely during a predetermined steady state of operation.

18. The controller of claim 17, wherein said operating-point determining device calculates said overall efficiency while shifting said engine operating point by a predetermined amount, shifts said engine operating point from an engine maximum efficiency point so that said overall efficiency is maximized, and performs restriction so that a total shift quantity of said shifted engine operating point does not exceed a predetermined upper-limit value.

19. A method for controlling a hybrid electric vehicle comprising:

causing at least a portion of engine power to be saved as stored power when said engine power is above a predetermined power level;

causing at least a portion of vehicle drive power to be provided from at least one of power generation and said stored power when said engine power is below a predetermined level;

determining engine operating points including an engine operating point that maximizes overall system efficiency based on overall system efficiency-related information extracted from engine input information, as well as based on a relationship between said overall efficiency-related information and said engine operating point; and

controlling operation of said hybrid-system based on said engine operating point.

20. The controller of claim 19, wherein said step of determining engine operating points further comprises maximizing said overall efficiency based on a fuel-consumption quantity of said engine, said steps of causing, and a vehicle drive-power requirement value.