LEFT-RIGHT WHEEL DRIVE FORCE DISTRIBUTION CONTROL APPARATUS FOR A VEHICLE

• US 20130073160A1
• Filed: 07/05/2011
• Published: 03/21/2013
• Est. Priority Date: 07/09/2010
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Tsushima, Yohei
• Granted Patent: US 8,788,170 B2
• Time in Patent Office: Days
• US Class Current: 701/69
• CPC Class Codes: B60K 17/344 having a transfer gear
• CPC Class Codes: B60K 2023/043 Control means for varying left-right torque distribution, e.g. torque vectoring
• CPC Class Codes: B60K 23/04 for differential gearing
• CPC Class Codes: B60W 2720/30 Wheel torque
• CPC Class Codes: F16H 2048/205 using the steering as a control parameter
• CPC Class Codes: F16H 48/19 consisting of two linked clutches
• CPC Class Codes: G05D 17/00 Control of torque; Control of mechanical power

Abstract

When a rear wheel total drive force is smaller than a rear wheel drive force difference and the rear wheel drive force difference cannot be accomplished by dividing the rear wheel total drive force between the left and right rear wheels, an inside wheel target drive force is not set to 0 and an outside wheel target drive force is not set to. Instead, the inside wheel target drive force is set to a default drive force that is a minimum value required to prevent a three-wheel drive state from occurring, and the outside wheel target drive force is set a value equal to the sum of the default drive force and the rear wheel drive force difference, which is a value with which the rear wheel drive force difference can be achieved under the condition of the inside wheel target drive force being equal to the default drive force.

Claims

1. A vehicle left-right wheel drive force distribution control apparatus comprising:

a controller programmed to executes a distributed output of drive forces to left and right drive wheels in accordance with a front-rear wheel drive force distribution control, the controller including

a total drive force computing section that sets a total drive force target value for in accordance with a vehicle operating state;

a drive force distribution section that sets a left-right drive force difference between the drive forces to be distributed to the left and right drive wheels in accordance with the vehicle operating state and that computes a front-rear drive force distribution to be attained between front and rear drive wheels and a left-right drive force distribution for the left and right drive wheels based on the left-right drive force difference and the total drive force target value;

a vehicle drive force insufficiency determining section that determines whether the total drive force target value is equal to or larger than the left-right drive force difference; and

a target drive force limiting section that distributes drive forces to the left and right drive wheels at the left and right drive force distribution values computed by the drive force distribution section upon the wheel drive force insufficiency determining section having determined that the total drive force target value is equal to or larger than the left-right drive force difference, and that limits a smaller value of the left and right drive force distribution values computed by the drive force distribution section a minimum allowable value upon the wheel drive force insufficiency determining section determining that the total drive force target value is smaller than the left-right drive force difference.

2. The vehicle left-right wheel drive force distribution control apparatus according to claim 1, wherein

the target drive force limiting section sets a larger of the left and right drive force distribution values to a value obtained by adding the left-right drive force difference to the minimum allowable value, upon the wheel drive force insufficiency determining section having determined that the total drive force target value is smaller than the left-right drive force difference.

5. The vehicle left-right wheel drive force distribution control apparatus according to claim 1, wherein

the drive force distribution section sets the front-rear drive force distribution between the front and rear drive wheels in accordance with a drive slippage degree of the left and right drive wheels, a longitudinal acceleration of the vehicle and an accelerator opening degree.

6. The vehicle left-right wheel drive force distribution control apparatus according to claim 2, further comprising

the drive force distribution section sets the front-rear drive force distribution between the front and rear drive wheels in accordance with a drive slippage degree of the left and right drive wheels, a longitudinal acceleration of the vehicle and an accelerator opening degree.

7. The vehicle left-right wheel drive force distribution control apparatus according to claim 1, further comprising

the drive force distribution section computes the left-right drive force distribution of the left and right drive wheels by:

estimating a longitudinal acceleration of the vehicle and a lateral acceleration of the vehicle, finding a left-right drive force difference necessary to dissolve an under-steered state of the vehicle based on a combination of the longitudinal and lateral accelerations, and setting the same as a steady-state control amount;

computing a target yaw rate based on a steering angle and a vehicle speed, finding a left-right wheel drive force difference corresponding to the target yaw rate, and setting the same as a transient control amount; and

distributing a sum value of the steady-state control amount and the transient control amount such that a left-right rear wheel drive difference targeted during a vehicle turning behavior is obtained.

8. The vehicle left-right wheel drive force distribution control apparatus according to claim 2, further comprising

the drive force distribution section computes the left-right drive force distribution of the left and right drive wheels by:

estimating a longitudinal acceleration of the vehicle and a lateral acceleration of the vehicle, finding a left-right drive force difference necessary to dissolve an under-steered state of the vehicle based on a combination of the longitudinal and lateral accelerations, and setting the same as a steady-state control amount;

computing a target yaw rate based on a steering angle and a vehicle speed, finding a left-right wheel drive force difference corresponding to the target yaw rate, and setting the same as a transient control amount; and

distributing a sum value of the steady-state control amount and the transient control amount such that a left-right rear wheel drive difference targeted during a vehicle turning behavior is obtained.

9. The vehicle left-right wheel drive force distribution control apparatus according to claim 5, further comprising

the drive force distribution section computes the left-right drive force distribution of the left and right drive wheels by:

estimating a longitudinal acceleration of the vehicle and a lateral acceleration of the vehicle, finding a left-right drive force difference necessary to dissolve an under-steered state of the vehicle based on a combination of the longitudinal and lateral accelerations, and setting the same as a steady-state control amount;

computing a target yaw rate based on a steering angle and a vehicle speed, finding a left-right wheel drive force difference corresponding to the target yaw rate, and setting the same as a transient control amount; and

distributing a sum value of the steady-state control amount and the transient control amount such that a left-right rear wheel drive difference targeted during a vehicle turning behavior is obtained.

10. The vehicle left-right wheel drive force distribution control apparatus according to claim 1, wherein

the controller is programmed to execute the distributed output of the drive forces to rear wheels of the vehicle as the left and right drive wheels.

11. The vehicle left-right wheel drive force distribution control apparatus according to claim 2, wherein

the controller is programmed to execute the distributed output of the drive forces to rear wheels of the vehicle as the left and right drive wheels.

12. The vehicle left-right wheel drive force distribution control apparatus according to claim 5, wherein

the controller is programmed to execute the distributed output of the drive forces to rear wheels of the vehicle as the left and right drive wheels.

3. (canceled)

4. (canceled)