Driving condition control method and system

• US 20040262067A1
• Filed: 06/17/2004
• Published: 12/30/2004
• Est. Priority Date: 06/18/2003
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Fujii, Takehito, Sawada, Mamoru, Matsumoto, Toshiki, Tashiro, Tsutomu, Kataoka, Motoaki, Mabuchi, Mamoru
• Granted Patent: US 7,169,083 B2
• Time in Patent Office: Days
• US Class Current: 180/282
• CPC Class Codes: B60K 28/16 responsive to, or preventing, skidding of wheels brake control systems for vehicle drive stability B60T8/1755; arrangements responsive to a speed condition for adjusting wheel braking force B60T8/32; control of vehicle driving stability otherwise than by controlling the propulsion unit only B60W30/02; preventing wheel slippage by reducing power in rail vehicles B61C15/00
• CPC Class Codes: B60K 28/165 acting on elements of the vehicle drive train other than the propulsion unit and brakes, e.g. transmission, clutch, differential acting on brakes B60T8/17
• CPC Class Codes: B60T 8/1755 Brake regulation specially adapted to control the stability of the vehicle, e.g. taking into account yaw rate or transverse acceleration in a curve road vehicle drive control systems for control of driving stability otherwise than by controlling a particular sub-unit B60W30/02
• CPC Class Codes: B60T 8/1766 Proportioning of brake forces according to vehicle axle loads, e.g. front to rear of vehicle
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/10 including control of change-speed gearings
• CPC Class Codes: B60W 10/184 with wheel brakes
• CPC Class Codes: B60W 2520/263 Slip values between front and rear axle
• CPC Class Codes: B60W 2520/28 Wheel speed

Abstract

In a driving condition control system, a sensing unit senses a first physical quantity indicative of a rotation of the first rotatable axle assembly and a second physical quantity indicative of a rotation of the second rotatable axle assembly. A determining unit compares the first and second physical quantities of the rotations of the first and second rotational axle assemblies and determines whether a driving condition of the vehicle is unstable according to the compared result. As a result, the unstable condition of the vehicle can be rapidly detected without detecting a yaw moment of the vehicle.

Claims

1. A driving condition control system installed in a vehicle, wherein said vehicle has a source of power for generating power, a first rotatable axle assembly to which a front wheel is attached, and a second rotatable axle assembly to which a rear wheel is attached, said power being transferred to the second rotatable axle assembly so that the second rotatable axle assembly is rotated, said driving condition control system comprising:

a sensing unit configured to sense a first physical quantity indicative of a rotation of the first rotatable axle assembly and a second physical quantity indicative of a rotation of the second rotatable axle assembly; and

a determining unit configured to compare the first and second physical quantities of the rotations of the first and second rotational axle assemblies and to determine whether a driving condition of the vehicle is unstable according to the compared result.

2. A driving condition control system according to claim 1, wherein said sensing unit is configured to sense a first rotational speed of the first rotational axle assembly and a second rotational speed of the second rotational axle assembly as the first and second physical quantities.

3. A driving condition control system according to claim 2, wherein said determining unit is configured to compare the first rotational speed of the first rotational axle assembly and the second rotational speed of the second rotational axle assembly and to determine whether the vehicle becomes a first unstable condition of inside turning or a second unstable condition of outside turning according to the compared result.

4. A driving condition control system according to claim 1 further comprising:

when said determining unit determines that the driving condition of the vehicle is unstable, an adjusting unit configured to adjust the power generated by the source of power.

5. A driving condition control system according to claim 4 further comprising an acceleration detecting unit configured to detect an acceleration of the vehicle and to determine whether or not the vehicle is being accelerated or being braked according to the detected acceleration, and

wherein, when the acceleration detecting unit determines that the vehicle is being accelerated or being braked, said adjusting unit adjusts the power in different manners according to the determination result representing that the vehicle is being accelerated or is being braked.

6. A driving condition control system according to claim 5, wherein, when the determining unit determines that the driving condition of the vehicle is unstable and the acceleration detecting unit determines that the vehicle is being accelerated, said adjusting unit is configured to decrease the power so that the decreased power is smaller than predetermined power, said predetermined power being set by an operation of a driver in a case where the determining unit determines that the driving condition of the vehicle is stable.

7. A driving condition control system according to claim 5, wherein, when the determining unit determines that the driving condition of the vehicle is unstable and the acceleration detecting unit determines that the vehicle is being accelerated, said adjusting unit is configured to keep the power constant.

8. A driving condition control system according to claim 5, wherein, when the determining unit determines that the driving condition of the vehicle is unstable and the acceleration detecting unit determines that the vehicle is being braked, said adjusting unit is configured to increase the power so that the increased power is larger than predetermined power, said predetermined power being set by an operation of a driver in a case where the determining unit determines that the driving condition of the vehicle is stable.

9. A driving condition control system according to claim 5, wherein, when the determining unit determines that the driving condition of the vehicle is unstable and the acceleration detecting unit detects that the vehicle is being braked, said adjusting unit is configured to perform one of processes to keep the power constant and to decrease the power.

10. A driving condition control system according to claim 1, further comprising:

a plurality of brake force generating units mechanically connected to the (front and rear) wheels of the vehicle and configured to generate brake forces to apply the brake forces to the front and rear wheels, respectively; and

a brake force control unit operatively connected to the plurality of brake force generating units and configured to control the generated brake forces,

when said determining unit determines that the driving condition of the vehicle is unstable, said brake force control unit controls the plurality of brake force generating units to generate the brake forces, thereby adjusting the power by the brake forces.

11. A driving condition control system according to claim 10 further comprising an acceleration detecting unit configured to detect an acceleration of the vehicle and to determine whether or not the vehicle is being accelerated or being braked according to the detected acceleration, and

wherein, when the acceleration detecting unit determines that the vehicle is being accelerated or being braked, said brake force control unit controls the brake forces in different manners according to the determination result representing that the vehicle is being accelerated or is being braked.

12. A driving condition control system according to claim 11, wherein, when the determining unit determines that the driving condition of the vehicle is unstable and the acceleration detecting unit determines that the vehicle is being accelerated, said brake force control unit is configured to adjust the brake forces to decrease them so that the decreased brake forces are smaller than predetermined force, said predetermined force being set by an operation of a driver in a case where the determining unit determines that the driving condition of the vehicle is stable.

13. A driving condition control system according to claim 10, wherein, when the determining unit determines that the driving condition of the vehicle is unstable and the acceleration detecting unit determines that the vehicle is being accelerated, said brake force control unit is configured to adjust the brake forces so that the brake force distributed to the front wheel is different from the brake force distributed to the rear wheel.

14. A driving condition control system according to claim 2, further comprising:

a plurality of brake force generating units mechanically connected to the front and rear wheels of the vehicle and configured to generate brake forces to apply the brake forces to the front and rear wheels, respectively; and

a brake force control unit operatively connected to the plurality of brake force generating units and configured to control the generated brake forces; and

an acceleration detecting unit configured to detect an acceleration of the vehicle and to determine whether or not the vehicle is being accelerated or being braked according to the detected acceleration,

wherein, when the determining unit determines that the driving condition of the vehicle is unstable, said brake force control unit controls the brake force generating units to generate the brake forces, thereby adjusting the power by the brake forces,

and wherein, when the determining unit determines that the driving condition of the vehicle is unstable, the acceleration detecting unit determines that the vehicle is being braked, and the sensing unit senses that the first rotational speed of the first rotational axle assembly is faster than the second rotational speed of the second rotational axle assembly, said brake force control unit controls the brake forces so that the brake force distributed to the front wheel is smaller than the brake force distributed to the rear wheel.

15. A driving condition control system according to claim 14, wherein, when the determining unit determines that the driving condition of the vehicle is unstable, the acceleration detecting unit determines that the vehicle is being braked, and the sensing unit senses that the first rotational speed of the first rotational axle assembly is later than the second rotational speed of the second rotational axle assembly, said brake force control unit controls the brake forces so that the brake force distributed to the front wheel is larger than the brake force distributed to the rear wheel.

16. A driving condition control system according to claim 1, wherein said vehicle is equipped with an automatic transmission that has a gear box and mechanically connected between the source of power and the second rotatable axle assembly, said automatic transmission changing gear ratios of the gear box to convert the power generated by the source to torque based on the gear ratios, thereby transferring the torque to the second axle assembly, further comprising:

when said determining unit determines that the driving condition of the vehicle is unstable, an adjusting unit electrically connected to the automatic transmission and configured to control the automatic transmission to change the gear ratios, thereby adjusting the torque transferred to the second axle assembly.

17. A driving condition control system according to claim 1, further comprising a turning determining unit configured to determine whether the vehicle is turning,

wherein said sensing unit starts to sense the first physical quantity of the rotation of the first rotatable axle assembly and the second physical quantity indicative of the rotation of the second rotatable axle assembly in response to the determination of the turning determining unit 1 in that the vehicle is turning.

18. A program product having a computer-readable medium storing therein a program readable by an electronic control unit, said electronic control unit being installed in a vehicle, wherein said vehicle has a source of power for generating power, a first rotatable axle assembly to which a front wheel is attached, a second rotatable axle assembly to which a rear wheel is attached, said power being transferred to the second rotatable axle assembly as torque so that the second rotatable axle assembly is rotated, and a sensing unit that senses a first physical quantity indicative of a rotation of the first rotatable axle assembly and a second physical quantity indicative of a rotation of the second rotatable axle assembly, said program causing an electronic control unit to:

receive the first physical quantity indicative of the rotation of the first rotatable axle assembly and the second physical quantity indicative of the rotation of the second rotatable axle assembly from the sensing unit;

compare the first and second physical quantities of the rotations of the first and second rotational axle assemblies;

determine whether a driving condition of the vehicle is unstable according to the compared result; and

when said determining step determines that the driving condition of the vehicle is unstable, adjust the torque transferred to the second axle assembly.

19. A method of controlling a driving condition of a vehicle, wherein said vehicle has a source of power for generating power, a first rotatable axle assembly to which a front wheel is attached, and a second rotatable axle assembly to which a rear wheel is attached, said power being transferred to the second rotatable axle assembly so that the second rotatable axle assembly is rotated, said method comprising:

sensing a first physical quantity indicative of a rotation of the first rotatable axle assembly and a second physical quantity indicative of a rotation of the second rotatable axle assembly; and

comparing the first and second physical quantities of the rotations of the first and second rotational axle assemblies to determine whether a driving condition of the vehicle is unstable according to the compared result.

20. A method of controlling a driving condition of a vehicle according to claim 19, wherein said sensing step includes sensing a first rotational speed of the first rotational axle assembly and a second rotational speed of the second rotational axle assembly as the first and second physical quantities.

21. A method of controlling a driving condition of a vehicle according to claim 19, wherein said determining step includes comparing the first rotational speed of the first rotational axle assembly and the second rotational speed of the second rotational axle assembly to determine whether the vehicle becomes a first unstable condition of inside turning or a second unstable condition of outside turning according to the compared result.

22. A method of controlling a driving condition of a vehicle according to claim 19 further comprising:

when said determining step determining that the driving condition of the vehicle is unstable, adjusting the power generated by the source of power.

23. A method of controlling a driving condition of a vehicle according to claim 22, further comprising detecting an acceleration of the vehicle to determine whether or not the vehicle is being accelerated or being braked according to the detected acceleration, and

wherein, when said detecting step determines that the vehicle is being accelerated or being braked, said adjusting step adjusts the power in different manners according to the determination result representing that the vehicle is being accelerated or is being braked.

24. A method of controlling a driving condition of a vehicle according to claim 23, wherein, when the determining step determines that the driving condition of the vehicle is unstable and the detecting step determines that the vehicle is being accelerated, said adjusting step decreases the power so that the decreased power is smaller than predetermined power, said predetermined power being set by an operation of a driver in a case where the determining step determines that the driving condition of the vehicle is stable.

25. A method of controlling a driving condition of a vehicle according to claim 23, wherein, when the determining step determines that the driving condition of the vehicle is unstable and the detecting step determines that the vehicle is being accelerated, said adjusting step keeps the power constant.

26. A method of controlling a driving condition of a vehicle according to claim 23, wherein, when the determining step determines that the driving condition of the vehicle is unstable and the detecting step determines that the vehicle is being braked, said adjusting step increases the power so that the increased power is larger than predetermined power, said predetermined power being set by an operation of a driver in a case where the determining step determines that the driving condition of the vehicle is stable.

27. A method of controlling a driving condition of a vehicle according to claim 23, wherein, when the determining step determines that the driving condition of the vehicle is unstable and the detecting step detects that the vehicle is being braked, said adjusting step performs one of processes to keep the power constant and to decrease the power.

28. A method of controlling a driving condition of a vehicle according to claim 19, further comprising:

generating brake forces to apply the brake forces to the front and rear wheels, respectively; and

controlling the generated brake forces,

when said determining step determines that the driving condition of the vehicle is unstable, said controlling step using the generated brake forces to adjust the power by the brake forces.

29. A method of controlling a driving condition of a vehicle according to claim 28, further comprising detecting an acceleration of the vehicle to determine whether or not the vehicle is being accelerated or being braked according to the detected acceleration, and

wherein, when the detecting step determines that the vehicle is being accelerated or being braked, said controlling step controls the brake forces in different manners according to the determination result representing that the vehicle is being accelerated or is being braked.

30. A method of controlling a driving condition of a vehicle according to claim 29, wherein, when the determining step determines that the driving condition of the vehicle is unstable and the detecting step determines that the vehicle is being accelerated, said controlling step decreases the brake forces so that the decreased brake forces are smaller than predetermined force, said predetermined force being set by an operation of a driver in a case where the determining unit determines that the driving condition of the vehicle is stable.

31. A method of controlling a driving condition of a vehicle according to claim 28, wherein, when the determining step determines that the driving condition of the vehicle is unstable and the detecting step determines that the vehicle is being accelerated, said controlling step controls the brake forces so that the brake force distributed to the front wheel is different from the brake force distributed to the rear wheel.

32. A method of controlling a driving condition of a vehicle according to claim 20, further comprising:

generating brake forces to apply the brake forces to the front and rear wheels, respectively; and

controlling the generated brake forces; and

detecting an acceleration of the vehicle to determine whether or not the vehicle is being accelerated or being braked according to the detected acceleration,

wherein, when the determining step determines that the driving condition of the vehicle is unstable, said controlling step uses the generated brake forces to adjust the torque by the brake forces,

and wherein, when the determining step determines that the driving condition of the vehicle is unstable, the detecting step determines that the vehicle is being braked, and the sensing step senses that the first rotational speed of the first rotational axle assembly is faster than the second rotational speed of the second rotational axle assembly, said controlling step controls the brake forces so that the brake force distributed to the front wheel is smaller than the brake force distributed to the rear wheel.

33. A method of controlling a driving condition of a vehicle according to claim 32, wherein, when the determining step determines that the driving condition of the vehicle is unstable, the detecting step determines that the vehicle is being braked, and the sensing step senses that the first rotational speed of the first rotational axle assembly is later than the second rotational speed of the second rotational axle assembly, said controlling step controls the brake forces so that the brake force distributed to the front wheel is larger than the brake force distributed to the rear wheel.