VEHICLE MOTION CONTROL DEVICE

• US 20100332099A1
• Filed: 06/24/2010
• Published: 12/30/2010
• Est. Priority Date: 06/30/2009
• Status: Active Grant

• Current Assignee: Advics Company Limited (Aisin Corp.)
• Original Assignee: Advics Company Limited (Aisin Corp.)
• Inventors: KATO, Toshihisa
• Granted Patent: US 8,589,050 B2
• Time in Patent Office: Days
• US Class Current: 701/90
• CPC Class Codes: B60T 2230/03 Overturn, rollover
• CPC Class Codes: B60T 8/17554 specially adapted for enhancing stability around the vehicles longitudinal axle, i.e. roll-over prevention road vehicle drive control systems for roll-over prevention otherwise than by controlling a particular sub-unit B60W30/04

Abstract

A vehicle motion control device obtains an actual slip ratio and a physical quantity representing a state of motion of the vehicle in a direction of lateral overturn. The device is in an anti-lateral overturn mode when the physical quantity is larger than or equal to a motion state threshold. The device obtains an increase gradient and determines whether or not the increase gradient is larger than or equal to a predetermined increase gradient threshold, wherein the increase gradient is a ratio of an increase amount of the physical quantity to a decrease amount of the actual slip ratio. The device decreases, when the device is in the anti-lateral overturn mode and the increase gradient is larger than or equal to the increase gradient threshold, a speed of depressurization of a wheel cylinder pressure.

Claims

1. A vehicle motion control device, comprising:

a motion state obtaining means for obtaining, once per a predetermined calculation period, a physical quantity and an actual slip ratio being actually generated at a wheel of a vehicle, the physical quantity representing a state of motion of the vehicle in a direction of lateral overturn;

a mode setting means for being, in an anti-lateral overturn mode when the physical quantity obtained by the motion state obtaining means is larger than or equal to a motion state threshold, the anti-lateral overturn mode being for suppressing the lateral overturn of the vehicle;

an increase gradient obtaining means for obtaining an increase gradient which is a ratio of an increase amount of the physical quantity to a decrease amount of the actual slip ratio;

an increase gradient determination means for determining whether or not the increase gradient obtained by the increase gradient obtaining means is larger than or equal to a predetermined increase gradient threshold; and

a depressurization speed suppression means for decreasing, when the vehicle motion control device is in the anti-lateral overturn mode and the increase gradient determination means determines that the increase gradient is larger than or equal to the increase gradient threshold, a speed of depressurization of a wheel cylinder pressure at a wheel cylinder for generating a brake force at the wheel, compared to when it is neither determined that the increase gradient is larger than nor equal to the increase gradient threshold.

2. The vehicle motion control device according to claim 1, wherein the depressurization speed suppression means changes a way of decreasing the speed of the depressurization based on a total weight of the vehicle so that the speed of the depressurization becomes smaller as the total weight of the vehicle increases.

3. The vehicle motion control device according to claim 1, wherein

the increase gradient obtaining means:

sets a range of the actual slip ratio within which the increase gradient is larger than a predetermined increase gradient threshold;

determines that the increase gradient is larger than or equal to the increase gradient threshold when the actual slip ratio obtained by the motion state obtaining means is within the range; and

determines that the increase gradient is neither larger than nor equal to the increase gradient threshold when the actual slip ratio obtained by the motion state obtaining means is not within the range, and

the increase gradient determination means determines whether or not the increase gradient is larger than or equal to the increase gradient based on the result of determination of the increase gradient obtaining means.

4. The vehicle motion control device according to claim 1, wherein

the increase gradient obtaining means:

includes a reference slip ratio setting means for obtaining a largest value of the absolute value of the physical quantity obtained during a time range between a present calculation period and a time instance when the vehicle motion control device enters the anti-lateral overturn mode, and also for setting a reference slip ratio to the actual slip ratio obtained when the largest value of the absolute value of the physical quantity is obtained;

determines that the increase gradient is larger than or equal to the increase gradient threshold when the actual slip ratio obtained at the present calculation period by the motion state obtaining means is within a range between the reference slip ratio and a sum of the reference slip ratio and a predetermined constant value; and

determines that the increase gradient is neither larger than nor equal to the increase gradient threshold when the actual slip ratio obtained at the present calculation period by the motion state obtaining means is not within the range between the reference slip ratio and the sum of the reference slip ratio and a predetermined constant value, and

the increase gradient determination means determines whether or not the increase gradient is larger than or equal to the increase gradient based on the result of determination of the increase gradient obtaining means.

5. The vehicle motion control device according to claim 4, wherein the depressurization speed suppression means changes the way of decreasing the speed of the depressurization so that the speed of the depressurization becomes smaller as the difference between the actual slip ratio obtained at the present calculation period by the motion state obtaining means and the reference slip ratio set by the reference slip ratio setting means is smaller.

6. The vehicle motion control device according to claim 1, wherein the increase gradient obtaining means directly obtains the increase gradient which is the ratio of the increase amount of the physical quantity to the decrease amount of the actual slip ratio.

7. The vehicle motion control device according to claim 6, wherein the depressurization speed suppression means changes the way of decreasing the speed of the depressurization so that the speed of the depressurization becomes smaller as the increase gradient directly obtained by the increase gradient obtaining means increases.

8. The vehicle motion control device according to claim 1, further comprising a boosting speed enhancement means for increasing, when the vehicle motion control device is in the anti-lateral overturn mode and the increase gradient determination means determines that the increase gradient is larger than or equal to the increase gradient threshold, a speed of pressure boosting of the wheel cylinder pressure at the wheel cylinder for generating the brake force at the wheel, compared to when it is neither determined that the increase gradient is larger than nor equal to the increase gradient threshold.

9. The vehicle motion control device according to claim 2, wherein

the increase gradient obtaining means:

sets a range of the actual slip ratio within which the increase gradient is larger than a predetermined increase gradient threshold;

determines that the increase gradient is larger than or equal to the increase gradient threshold when the actual slip ratio obtained by the motion state obtaining means is within the range; and

determines that the increase gradient is neither larger than nor equal to the increase gradient threshold when the actual slip ratio obtained by the motion state obtaining means is not within the range, and

the increase gradient determination means determines whether or not the increase gradient is larger than or equal to the increase gradient based on the result of determination of the increase gradient obtaining means.

10. The vehicle motion control device according to claim 2, wherein

the increase gradient obtaining means:

includes a reference slip ratio setting means for obtaining a largest value of the absolute value of the physical quantity obtained during a time range between a present calculation period and a time instance when the vehicle motion control device enters the anti-lateral overturn mode, and also for setting a reference slip ratio to the actual slip ratio obtained when the largest value of the absolute value of the physical quantity is obtained;

determines that the increase gradient is larger than or equal to the increase gradient threshold when the actual slip ratio obtained at the present calculation period by the motion state obtaining means is within a range between the reference slip ratio and a sum of the reference slip ratio and a predetermined constant value; and

determines that the increase gradient is neither larger than nor equal to the increase gradient threshold when the actual slip ratio obtained at the present calculation period by the motion state obtaining means is not within the range between the reference slip ratio and the sum of the reference slip ratio and a predetermined constant value, and

the increase gradient determination means determines whether or not the increase gradient is larger than or equal to the increase gradient based on the result of determination of the increase gradient obtaining means.

11. The vehicle motion control device according to claim 10, wherein the depressurization speed suppression means changes the way of decreasing the speed of the depressurization so that the speed of the depressurization becomes smaller as the difference between the actual slip ratio obtained at the present calculation period by the motion state obtaining means and the reference slip ratio set by the reference slip ratio setting means is smaller.

12. The vehicle motion control device according to claim 2, wherein the increase gradient obtaining means directly obtains the increase gradient which is the ratio of the increase amount of the physical quantity to the decrease amount of the actual slip ratio.

13. The vehicle motion control device according to claim 12, wherein the depressurization speed suppression means changes the way of decreasing the speed of the depressurization so that the speed of the depressurization becomes smaller as the increase gradient directly obtained by the increase gradient obtaining means increases.

14. The vehicle motion control device according to claim 2, further comprising a boosting speed enhancement means for increasing, when the vehicle motion control device is in the anti-lateral overturn mode and the increase gradient determination means determines that the increase gradient is larger than or equal to the increase gradient threshold, a speed of pressure boosting of the wheel cylinder pressure at the wheel cylinder for generating the brake force at the wheel, compared to when it is neither determined that the increase gradient is larger than nor equal to the increase gradient threshold.