Generator control device for an electrical automobile

• US 6,470,985 B1
• Filed: 09/04/1998
• Issued: 10/29/2002
• Est. Priority Date: 09/05/1997
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Kaneko, Yutaro, Hirano, Hiroyuki, Kikuchi, Toshio, Idoguchi, Ryuichi, Aso, Takeshi, Inada, Eiji, Kitada, Shinichiro
• Primary Examiner(s): Johnson, Brian L.
• Assistant Examiner(s): PHAN, HAU VAN
• Application Number:
  US09/148,701
• Time in Patent Office: 1,516 Days
• Field of Search: 180/65.1, 180/65.2, 180/65.4, 180/309, 180/65.3, 180/65.6, 701/22, 748/62, 748/66, 477/43, 477/44, 477/46
• US Class Current: 180/65.245
• CPC Class Codes: B60K 6/46 Series type
• CPC Class Codes: B60L 2240/445 Temperature
• 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 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 2510/0676 Engine temperature
• CPC Class Codes: B60W 2510/068 Engine exhaust temperature
• CPC Class Codes: B60W 2710/0644 Engine speed
• CPC Class Codes: B60W 2710/0666 Engine torque
• CPC Class Codes: Y02T 10/40 Engine management systems
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y10S 903/903 having energy storing means, e.g. battery, capacitor
• CPC Class Codes: Y10S 903/917 with transmission for changing gear ratio

Abstract

An engine is activated to drive a generator when an electrical output is required. The required electrical output (PO) is searched and the necessary engine output is calculated. The basic driving point (NO, TO) which obtains maximum fuel efficiency is set at that output (S101-S105). The load of the generator is controlled so as to reach the set basic driving point. When the catalyst temperature is lower than a set value, while maintaining the required electrical output, the basic driving point is varied to a driving point (Ncold, Tcold) which will raise the exhaust gas temperature (S106-108). Furthermore when the temperature of the peripheral engine components in the engine room is higher than a set value, while maintaining the required electrical output, the driving point is varied to a driving point (Nheat, Theat) which will lower the exhaust gas temperature (S109-S111). Hence while maintaining the electrical output, it is possible satisfy each component temperature condition. Therefore while maintaining drivability, fuel efficiency performance, lowering exhaust gas emissions and component deterioration can suppressed.

Claims

1. A generator control device for a hybrid automobile which includes an electrical motor used to drive the automobile, a battery which supplies electricity to said electrical motor, a generator which supplies electricity to said electrical motor and to said battery, an exhaust gas purification catalyst disposed in an exhaust passage, and an engine which drives said generator, the generator control device comprising:

a controller which controls output of the engine at least when a charge of the battery falls below a set value so that the generator is driven and an amount of electrical output meets a required electrical output wherein

said controller includes a microcomputer and is programmed to;

maintain an engine output which is equal to an engine output at a basic driving point when a temperature of the catalyst is lower than a set temperature, said basic driving point is a point of optimal efficiency of the engine, and

vary a rotation speed of said engine and a torque of said engine as to raise the temperature of the catalyst when the temperature of the catalyst is lower than said set temperature, while maintaining a constant engine output by an increase of the engine rotation speed and a decrease of the engine load, so the temperature of the catalyst is raised.

2. A generator control device according to claim 1, wherein said controller, on comparison with an engine exhaust gas temperature at maximum fuel efficiency driving conditions at an equal engine output, employs different variation characteristics with respect to the rotation speed when a required exhaust gas temperature is high and when the required exhaust gas temperature is low.

3. A generator control device according to claim 2, wherein said controller, as an exhaust gas temperature condition of said engine, varies the load on the generator towards a rotation speed that increases the exhaust gas temperature while maintaining a constant engine output when the temperature of the catalyst is lower than the set value.

4. A generator control device according to claim 3, wherein said controller varies the load on the generator depending on a deviation of the temperature of said catalyst from the set temperature.

5. A generator control device according to claim 4, wherein said controller estimates the catalyst temperature on an elapsed time after the activation of the engine.

6. A generator control device according to claim 5, wherein said controller varies the generator load towards a rotation speed that lowers the exhaust gas temperature at an equal engine output when the temperature of peripheral engine components of an engine room are higher than a set temperature.

7. A generator control device according to claim 6, wherein said controller, when the engine exhaust gas temperature is not lowered sufficiently to reach the set temperature even if the load on said generator is varied towards a rotation speed that lowers the exhaust gas temperature, said controller gradually reduces the engine output while maintaining a rotation speed to minimize the exhaust gas temperature.

8. A generator control device which controls output of an engine to drive a generator when a charge of a battery, which supplies electricity to an electrical motor to drive an automobile, is lower than a set value, so that electrical output achieves required electrical output, the generator control device comprising:

a microcomputer that is programmed to;

maintain an engine output which is equal to an engine output at a basic driving point when a temperature of an exhaust gas purification catalyst disposed in an exhaust passage is lower than a set temperature, said basic driving point is a point of optimal efficiency of the engine,

determine required conditions of engine exhaust gas temperature, and

vary a rotation speed of said engine and a torque of said engine as to raise the temperature of the catalyst when the temperature of the catalyst is lower than said set temperature by an increase of the engine rotation speed and a decrease of the engine load at a maximum fuel efficiency such that the required conditions of engine exhaust gas temperature are achieved.

9. A method of operating a generator control device of a series hybrid electrical vehicle that includes an electric motor used to drive the automobile, a battery which supplies electricity to said electric motor, a generator which supplies electricity to said electric motor and to said battery, an exhaust gas purification catalyst disposed in an exhaust passage and an engine which drives said generator, the method comprising:

maintaining an engine output which is equal to an engine output at a basic driving point when a temperature of an exhaust gas purification catalyst disposed in an exhaust passage is lower than a set temperature, said basic driving point is a point of optimal efficiency of the engine; and

varying a rotation speed of said engine and a torque of said engine as to raise the temperature of the catalyst when the temperature of the catalyst is lower than said set temperature, while maintaining a constant engine output by an increase of the engine rotation speed and a decrease of the engine load, so the temperature of the catalyst is raised.

10. The method according to claim 9, further comprising:

when said catalyst temperature is lower than said set temperature, calculating a temperature differential of said set temperature and said catalyst temperature, and wherein said varying step further comprises

sending an engine rotation command to the engine to adjust a rotation of the engine when said catalyst temperature is lower than said set temperature.

11. The method according to claim 10, wherein said maintaining step comprises:

sending a generator load command to the generator to adjust the load on the generator to increase said catalyst temperature.

12. The method according to claim 9, further comprising:

determining whether a temperature of a first sensor has reached a temperature corresponding to a functional limit of said first sensor when said catalyst temperature is greater than said set temperature.

13. The method according to claim 12, further comprising:

reducing required electrical output when said temperature corresponding to a functional limit equals an output minimum exhaust temperature;

determining engine rotation speed and generator load values; and

sending command signals to the engine and the generator corresponding to said engine rotation speed and generator load values.

14. The method according to claim 9, further comprising:

reading a degree of charge of the battery and a change in the charge of the battery;

determining whether electricity is to be produced, wherein when it is determined that electricity is to be produced,

activating the generator, and

determining a generator electrical output; and

setting a generator load value and an engine rotation speed command based on predetermined basic driving points that represent maximum fuel efficiency on the basis of engine rotation speed and engine load.

15. The method according to claim 14, wherein said generator electrical output is determined corresponding to said degree of charge, said change in the charge of the battery, and vehicle speed.

16. The method according to claim 14, further comprising:

determining a first and second elapsed time after said activation;

determining engine rotation speed and engine load corresponding to the generator electrical output at said first and second elapsed times; and

wherein said varying comprises

varying the load on the generator to change the rotation speed of the engine on a basis of the engine rotation speed and engine load determinations at said first and second elapsed times to maximize fuel efficient operation.