Electric vehicle drive train with direct coupling transmission

• US 5,403,244 A
• Filed: 04/15/1993
• Issued: 04/04/1995
• Est. Priority Date: 04/15/1993
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Tankersley, Jerome B., Konrad, Charles E., Boothe, Richard W.
• Primary Examiner(s): Wright, Dirk
• Application Number:
  US08/016,798
• Time in Patent Office: 719 Days
• Field of Search: 477/20, 180/65.3, 180/65.8, 475/153
• US Class Current: 477/20
• CPC Class Codes: B60K 1/00 Arrangement or mounting of electrical propulsion units B60K7/00 takes precedence; arrangement or mounting of plural diverse prime-movers for mutual or common propulsion B60K6/00; electric transmission arrangements B60K17/12; electric equipment or propulsion of electrically-propelled vehicles per se B60L; current-collectors for power supply lines of electrically-propelled vehicles B60L5/00
• CPC Class Codes: B60K 1/04 of the electric storage means for propulsion exchanging batteries for electric propulsion of vehicles B60L53/80; for auxiliary purposes only B60R16/04; supplying batteries to, or removing batteries from, vehicles B60S5/06
• CPC Class Codes: B60K 17/08 of mechanical type
• CPC Class Codes: B60K 17/16 of differential gearing
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/115 with planetary gears
• CPC Class Codes: B60W 2510/081 Speed
• CPC Class Codes: B60W 2710/1005 Transmission ratio engaged
• CPC Class Codes: B60W 30/18 Propelling the vehicle
• CPC Class Codes: F16H 2059/083 Overdrive or overdrive cut-off
• CPC Class Codes: F16H 61/0437 by using electrical signals F16H61/0403 and F16H61/061 take precedence

Abstract

An electric vehicle drive train includes an electric motor and an associated speed sensor, a transmission operable in a speed reduction mode or a direct coupled mode, and a controller responsive to the speed sensor for operating the transmission in the speed reduction mode when the motor is below a predetermined value, and for operating the motor in the direct coupled mode when the motor speed is above a predetermined value. The controller reduces the speed of the motor, such as by regeneratively braking the motor, when changing from the speed reduction mode to the direct coupled mode. The motor speed may be increased when changing from the direct coupled mode to the speed reduction mode. The transmission is preferably a single stage planetary gearbox.

Claims

1. A drive train for an electric vehicle, said drive train comprising:

a traction battery;

an electric motor associated with said traction battery and operable in one of a drive mode for driving one or more wheels of the vehicle and a regenerative braking mode for recharging said traction battery;

sensing means connected to said electric motor for sensing rotational speed thereof;

transmission means connected to said electric motor for rotatably driving one or more wheels of the vehicle in one of a speed reduction mode and a direct coupled mode; and

control means connected to said traction battery, said electric motor, and said transmission means, and being responsive to said sensing means for operating said transmission means in said speed reduction mode when a rotational speed of said electric motor is below a first predetermined value and for operating said transmission means in said direct coupled mode when a rotational speed of said electric motor is above a second predetermined value, said control means comprising speed synchronizing means for operating said electric motor in said regenerative braking mode to reduce a rotational speed of said electric motor to a corresponding reduced rotational speed of said transmission means in said direct coupled mode when changing said transmission means from said speed reduction mode to said direct coupled mode.

2. A drive train according to claim 1 wherein said transmission means further comprises freewheeling means for decoupling said electric motor and said transmission means;

and wherein said control means further comprises means cooperating with said freewheeling means for decoupling said electric motor and said transmission means while changing rotational speed of said electric motor to facilitate changing between said speed reduction mode and said direct coupled mode.

3. A drive train according to claim 2 wherein said speed synchronizing means comprises means for increasing rotational speed of said electric motor to substantially match to a corresponding increased rotational speed of said transmission means in said speed reduction mode when changing said transmission means from said direct coupled mode to said speed reduction mode.

4. A drive train according to claim 1 further comprising driver selector means connected to said control means and cooperating therewith for permitting a driver to select said transmission means to operate only in said speed reduction mode irrespective of a rotational speed of said motor.

5. A drive train according to claim 1 wherein said transmission means has a predetermined reduction ratio in the range of about 5:

1 to 15;

1 when in said speed reduction mode.

6. A drive train according to claim 1 wherein said transmission means comprises a single stage planetary gearbox.

7. A drive train according to claim 6 wherein said single stage planetary gearbox comprises a housing, a releasably lockable ring gear positioned within said housing, a plurality of planet gears and an associated planetary carrier positioned within said housing, and a sun gear cooperating with said planet gears;

and wherein said sun gear is connected to said motor and said planetary carrier drives the one or more wheels of the vehicle when said transmission means is in said speed reduction mode.

8. A drive train according to claim 1 wherein said electric motor is an induction motor.

9. A drive train according to claim 1 further comprising sensing means associated with said transmission means for sensing a rotational output speed thereof.

10. A drive train for an electric vehicle, said drive train comprising:

a traction battery;

an electric motor having an output shaft and being associated with said traction battery and operable in one of a drive mode for driving one or more wheels of the vehicle and a regenerative braking mode for recharging said traction battery;

a sensor associated with the output shaft of said electric motor for sensing a rotational speed thereof;

transmission means connected to said electric motor and comprising an output shaft for rotatably driving one or more wheels of the vehicle, said transmission means further comprising a planetary gearbox having an input coupled to said output shaft of said electric motor for operating in a speed reduction mode, and direct coupling means for coupling said motor output shaft to said output shaft of said transmission means for operating in a direct coupled mode; and

control means connected to said traction battery, said electric motor, and said transmission means, and being responsive to said sensor for operating said transmission means in said speed reduction mode when a rotational speed of said electric motor is below a first predetermined value and for operating said transmission means in said direct coupled mode when a rotational speed of said electric motor is above a second predetermined value,,., said control means comprising speed synchronizing means for operating said electric motor in said regenerative braking mode to reduce a rotational speed of said electric motor to a corresponding reduced rotational speed of said transmission means in said direct coupled mode when changing said transmission means from said speed reduction mode to said direct coupled mode.

11. A drive train according to claim 10 wherein said transmission means further comprises freewheeling means for decoupling said motor output shaft and said input of said transmission means;

and wherein said control means further comprises means cooperating with said freewheeling means for uncoupling said electric motor output shaft and said output shaft of said transmission means while changing rotational speed of said electric motor to facilitate changing said transmission means between said speed reduction mode and said direct coupled mode,

12. A drive train according to claim 11 wherein said speed synchronizing means comprises means for increasing rotational speed of said electric motor output shaft to substantially match to a corresponding increased rotational speed of said input of said transmission means in said speed reduction mode when changing said transmission means from said direct coupled mode to said speed reduction mode.

13. A drive train according to claim 10 further comprising driver selector means connected to said control means and cooperating therewith for permitting a driver to select said transmission means to operate only in said speed reduction mode irrespective of a rotational speed of said electric motor.

14. A drive train according to claim 10 wherein said planetary gearbox has a predetermined reduction ratio in the range of about 5:

1 to 15;

1.

15. An electric vehicle comprising:

a frame;

one or more wheels rotatably mounted to said frame;

a traction battery carried by said frame;

an electric motor connected to said traction battery and operable in one of a drive mode for driving one or more wheels of the vehicle and the regenerative braking mode for recharging said traction battery;

sensing means associated with said electric motor for sensing rotational speed thereof;

transmission means connected to said electric motor for rotatably driving the one or more wheels of the vehicle in one of a speed reduction mode and a direct coupled mode; and

control means connected to said transmission means and responsive to said sensing means for controlling said transmission means to operate in said speed reduction mode when a rotational speed of said electric motor is below a first predetermined value and for controlling said transmission means to operate in said direct coupled mode when a rotational speed of said electric motor is above a second predetermined value, said control means comprising speed synchronizing means for operating said electric motor in said regenerative braking mode to reduce a rotational speed of said electric motor to a corresponding reduced rotational speed of said transmission means in said direct coupled mode when changing said transmission means from said speed reduction mode to said direct coupled mode.

16. An electric vehicle according to claim 15 wherein said transmission means further comprises freewheeling means for decoupling said electric motor and said transmission means;

and wherein said control means further comprises means cooperating with said freewheeling means for decoupling said electric motor and said transmission means while changing rotational speed of said electric motor to facilitate changing between said speed reduction mode and said direct coupled mode.

17. An electric vehicle according to claim 16 wherein said speed synchronizing means further comprises means for increasing rotational speed of said motor to substantially match to a corresponding increased rotational speed of said transmission means in said speed reduction mode when changing said transmission means from said direct coupled mode to said speed reduction mode.

18. An electric vehicle according to claim 15 further comprising driver selector means connected to said control means and cooperating therewith for permitting a driver to select said transmission means to operate only in said speed reduction mode irrespective of a rotational speed of said motor.

19. A method for driving one or more wheels of an electric vehicle including a traction battery connected to an electric motor which is connected to the drive wheels through a transmission, the electric motor being operable in one of a drive mode for driving one or more of the drive wheels of the vehicle and a regenerative braking mode for recharging the traction battery, and the transmission being operable in either a speed reduction mode or a direct coupled mode, said method comprising the steps of:

sensing rotational speed of the electric motor;

operating the transmission in the speed reduction mode when a rotational speed of the electric motor is below a first predetermined value and operating the transmission in the direct coupled mode when a rotational speed of the electric motor is above a second predetermined value; and

substantially synchronizing rotational speed of the electric motor and the transmission when changing the transmission from the speed reduction mode to the direct coupled mode by operating the electric motor in the regenerative braking mode to reduce a rotational speed of the electric motor to substantially match to the transmission.

20. A method according to claim 19 further comprising the step of decoupling the electric motor and the transmission while changing rotational speed of the electric motor to match the transmission.

21. A method according to claim 19 further comprising the step of substantially synchronizing rotational speed of the electric motor and the transmission when changing the transmission from the direct coupled mode to the gear reduction mode by increasing a rotational speed of the electric motor to substantially match to the transmission.

22. A method according to claim 19 further comprising the step of operating the transmission only in the speed reduction mode irrespective of a rotational speed of the motor responsive to a driver selection of only the speed reduction mode.