Drive system for electric automobiles

• US 5,453,930 A
• Filed: 12/30/1992
• Issued: 09/26/1995
• Est. Priority Date: 02/08/1991
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Fukuyama, Yuichi, Fukino, Masato, Imaseki, Takashi, Origuchi, Masato
• Primary Examiner(s): Teska, Kevin J.
• Assistant Examiner(s): PARK, COLLIN
• Application Number:
  US07/998,974
• Time in Patent Office: 1,000 Days
• Field of Search: 364/424.01, 364/424.05, 364/425, 280/65.1, 280/65.2, 280/65.3, 280/65.5, 280/65.6, 280/65.8, 280/907, 318/139, 318/432, 318/433, 318/434
• US Class Current: 701/22
• 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 15/2036 Electric differentials, e.g. for supporting steering vehicles
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

A wheel motor drive system for electric automobiles comprises a car battery mounted on a vehicle body, at least two electric motors connected to vehicle wheels independently of each other, each of the motors having inherent torque characteristics with regard to a rotational speed and a maximum torque, sensors for monitoring a vehicle travelling condition, and a controller responsive to the vehicle travelling condition and the torque characteristics of the motors for controlling the motors at a low power consumption mode wherein at least one of the motors is driven within a high motor efficiency range so as to assure a long travel distance per one battery discharge.

Claims

1. A drive system for an electric automobile using a battery, comprising:

at least two electric motors connected to vehicle wheels independently of each other;

sensor means for monitoring a vehicle travelling condition;

means for deriving a required driving torque to be generated by said motors on the basis of said monitored vehicle travelling condition; and

control means responsive to the magnitude of said required torque, for controlling said motors at a low power consumption mode wherein an electric power supply to each of said motors is controlled so that said motors are driven to generate said required torque within a highest possible motor efficiency range,

wherein said control means includes decision means for comparing said required torque with a maximum torque of each of the motors and command means for controlling said electric power supply to each motor based on comparison results from said decision means and for operating at least one of said motors which would provide the highest possible motor efficiency at said required torque.

2. A drive system for an electric automobile using a battery, comprising:

at least two electric motors connected to vehicle wheels independently of each other, each of said motors having inherent torque characteristics with regard to a rotational speed and a maximum torque;

sensor means for monitoring a vehicle travelling condition;

memory means for storing torque characteristic data representative of said torque characteristics of said motors;

means for deriving a required driving torque to be generated by said motors on the basis of said monitored vehicle travelling condition and said torque characteristic data; and

control means responsive to the magnitude of said required torque, for controlling said motors at a low power consumption mode wherein an electric power supply to each of said motors is controlled so that said motors are driven to generate said required torque within a highest possible motor efficiency range,

wherein said control means includes decision means for comparing said required torque with a maximum torque of each of the motors and command means for controlling said electric power supply to each motor based on comparison results from said decision means and for operating at least one of said motors which would provide the highest possible motor efficiency at said required torque.

3. A wheel motor drive system for an electric automobile using a car battery, comprising:

a front-wheel drive motor having a driving connection with a front vehicle wheel;

a rear-wheel drive motor having a driving connection with a rear vehicle wheel, torque characteristics of said rear-wheel drive motor being different from those of said front-wheel drive motor;

sensor means for monitoring a vehicle travelling condition;

memory means for storing torque characteristic data representative of said torque characteristics of said motors;

means for deriving a required driving torque to be generated by said motors on the basis of said monitored vehicle travelling condition and said torque characteristic data;

control means responsive to the magnitude of said required torque, for controlling said motors at a low power consumption mode wherein an electric power supply to each of said motors is controlled so that said motors are driven to generate said required torque within a highest motor possible efficiency range; and

said control means selecting one of three motor drive modes comprising a first drive mode wherein only said rear-wheel drive motor is driven, a second drive mode wherein only said front-wheel drive motor is driven, and a third drive mode wherein both said front-wheel and rear-wheel drive motors are driven simultaneously with each other,

wherein said control means includes decision means for comparing said required torque with a maximum torque of each of the motors and command means for controlling said electric power supply to each motor based on comparison results from said decision means and for operating at least one of said motors which would provide the highest possible motor efficiency range at said required torque,

wherein one of said motors is a high-power motor and the other is a low-power motor, and said command means provides said first drive mode when said required torque is less than a maximum torque of said low-power motor, said second drive mode when said required torque is equal to or greater than the maximum torque of said low-power motor and less than a maximum torque of said high-power motor, and said third drive mode when said required torque is equal to or greater than the maximum torque of said high-power motor.

4. The wheel motor drive system as set forth in claim 3, wherein said sensor means includes a vehicle speed sensor for monitoring a vehicle speed and an accelerator sensor for monitoring a depressing amount of an accelerator-pedal, and said deriving means derives said required torque based on said monitored accelerator-pedal depressing amount and a maximum torque generated by each of said motors at said monitored vehicle speed.

5. The wheel motor drive system as set forth in claim 3, wherein said front-wheel drive motor is said high-power motor and said rear-wheel drive motor is said low-power motor.

6. The wheel motor drive system as set forth in claim 3, wherein said rear-wheel drive motor is said high-power motor and said front-wheel drive motor is said low-power motor.

7. A wheel drive system for an electric automobile using a battery, comprising:

at least two electric motors connected to vehicle wheels independently of each other;

sensor means for monitoring a vehicle travelling condition;

means for deriving a required driving torque to be generated by said motors on the basis of said monitored vehicle travelling condition;

means for determining whether said required torque exceeds a maximum torque of each of the motors and for generating a decision instruction; and

control means responsive to said decision instruction for deriving a combination of said motors necessary to provide a highest possible motor efficiency while producing said required torque and for controlling an electric power supply to each of said motors on the basis of said combination.

8. The wheel motor drive system as set forth in claim 7, wherein said control means controls the electric power supply to each motor to drive all of said motors when said means for determining outputs said decision instruction indicating that said required torque exceeds each of the maximum torque of the motors, and said control means controls the electric power supply to each motor in accordance with said combination.

9. The wheel motor drive system as set forth in claim 7, wherein said sensor means comprises a vehicle speed sensor for monitoring a vehicle speed and an accelerator sensor for monitoring a depressing amount of an accelerator-pedal, and said deriving means derives said required torque based on said accelerator-pedal depressing amount and said vehicle speed.

10. A wheel motor drive system for an electric automobile using a battery, comprising:

a front-wheel drive motor having a driving connection with a front vehicle wheel;

a rear-wheel drive motor having a driving connection with a rear vehicle wheel;

sensor means for monitoring a vehicle travelling condition;

means for deriving a required driving torque to be generated by said motors on the basis of said monitored vehicle travelling condition;

means for determining whether said required torque exceeds a maximum torque of each of the motors, and for generating a decision instruction; and

control means responsive to said decision instruction for deriving a combination of said motors necessary to provide a highest possible motor efficiency while producing said required torque and for controlling an electric power supply to each of said motors on the basis of said combination,

wherein one of said motors is a high-power motor and the other is a low-power motor, and said control means controls the power supply to each motor so that said both motors are driven with said high-power motor driven at its maximum torque when said required torque exceeds the maximum torque of said high-power motor, and that only said high-power motor is driven when said required torque is greater than or equal to the maximum torque of said low-power motor and less than the maximum torque of said high-power motor, and that only said low-power motor is driven when said required torque is less than the maximum torque of said low-power motor.

11. The wheel motor drive system as set forth in claim 10, wherein said front-wheel drive motor is said high-power motor and said rear-wheel drive motor is said low-power motor.

12. The wheel motor drive system as set forth in claim 10, wherein said rear-wheel drive motor is said high-power motor and said front-wheel drive motor is said low-power motor.