Device for controlling suspension shock absorbers of vehicles based upon phantom substitute therefor

• US 6,298,294 B1
• Filed: 06/14/2000
• Issued: 10/02/2001
• Est. Priority Date: 06/22/1999
• Status: Expired due to Fees

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Murata, Masahiro, Suzuki, Satoshi, Onuma, Toshio, Tomida, Koichi
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): ARTHUR JEANGLAUDE, GERTRUDE
• Application Number:
  US09/595,049
• Time in Patent Office: 475 Days
• Field of Search: 701/37, 701/38, 701/39, 188/299.1, 188/266.1, 280/5.512, 280/5.515
• US Class Current: 701/37
• CPC Class Codes: B60G 17/016 characterised by their responsiveness, when the vehicle is travelling, to specific motion, a specific condition, or driver input B60G17/017 takes precedence
• CPC Class Codes: B60G 17/018 characterised by the use of a specific signal treatment or control method

Abstract

A device for controlling damping coefficients of shock absorbers (22FL, 22FR, 22RL, 22RR) of a four wheeled vehicle constructs a phantom damping system composed of a phantom side shock absorber (122, 122F, 122R) disposed vertically at a lateral inside of a turn running of the vehicle to have a lower end movable along a ground surface together with the vehicle and an upper end vertically movable relative to the lower end with a first phantom damping coefficient (Cg, Cgf, Cgr) therebetween, and a phantom angular shock absorber (124, 124F, 124R) arranged to act between the upper end of the phantom side shock absorber and the vehicle body with a second phantom damping coefficient (Ca, Caf, Car) therebetween, whereby, when the damping coefficients of the shock absorbers are controlled to substantially equalize the phantom damping system with the actual damping system of the actual shock absorbers with respect to damping vertical and rolling movements of the vehicle body, the mass center of the vehicle body is lowered according to a rolling thereof during a turn running of the vehicle, as the vehicle body rolls around the upper end of the phantom side shock absorber located laterally inside of the turn running.

Claims

1. A device for controlling damping coefficients of shock absorbers of a four wheeled vehicle having a vehicle body, front left, front right, rear left and rear right wheels each supporting the vehicle body at a corresponding portion thereof, and the shock absorbers each acting between each of the wheels and the corresponding portion of the vehicle body, comprising:

means for constructing a phantom damping system composed of a phantom side shock absorber disposed vertically at a lateral inside of a turn running of the vehicle to have a lower end movable along a ground surface together with the vehicle and an upper end vertically movable relative to the lower end with a first phantom damping coefficient therebetween, and a phantom angular shock absorber arranged to act between the upper end of the phantom side shock absorber and the vehicle body with a second phantom damping coefficient therebetween, such that the phantom damping system provides the vehicle body with a substantially same phantom vertical damping force against a vertical movement of the vehicle body and a substantially same phantom angular damping moment against a rolling angular movement of the vehicle body as the shock absorbers acting between the wheels and the corresponding portions of the vehicle during a rolling of the vehicle body due to the turn running of the vehicle;

means for calculating values of at least the first and second phantom damping coefficients for obtaining an optimum rolling performance of the vehicle body by the phantom damping system during the turn running of the vehicle; and

means for controlling the damping coefficients of the shock absorbers acting between the wheels and the corresponding portions of the vehicle body based upon the calculated values of the first and second phantom damping coefficients.

2. A device according to claim 1, wherein the phantom damping system constructing means construct the phantom damping system as front and rear halves thereof corresponding separately to the shock absorbers acting between the front left and front right wheels and the corresponding portions of the vehicle body and to the shock absorbers acting between the rear left and rear right wheels and the corresponding portions of the vehicle body.

3. A device according to claim 2, wherein the calculating means further calculate lateral distances of the phantom side and angular shock absorbers of the front and rear halves of the phantom damping system according to a sum of an appropriately gained first product of steering angle and a square of vehicle speed and an appropriately gained second product of change rate of the steering angle and a square of vehicle speed, such that the lateral distances are generally increased according to an increase of the sum when the sum is not larger than a threshold value and are generally decreased according to an increase of the sum when the sum is larger than the threshold value.

4. A device according to claim 2, wherein the calculating means further calculate lateral distances of the phantom side and angular shock absorbers of the front and rear halves of the phantom damping system according to forces acting across the front and rear shock absorbers, such that lateral distances are generally increased according to an increase of the forces up to respective saturation values.

5. A device according to claim 2, wherein the calculating means further calculate a slip angle and a change rate of the slip angle of the vehicle body, thereby discriminating a slipping state of the vehicle about at least an oversteering state, and further calculate modification factor for proportionally modifying a lateral distance of the phantom side and angular shock absorber of the front half of the phantom damping system according to the absolute value of the slip angle of the vehicle body and the slipping state, such that when the vehicle is in the oversteering state, the modification factor for the lateral distance of the front half of the phantom damping system is generally increased according to an increase of the absolute value of the slip angle.

6. A device according to claim 2, wherein the calculating means further calculate a slip angle and a change rate of the slip angle of the vehicle body, thereby discriminating a slipping state of the vehicle about at least an understeering state, and further calculate modification factor for proportionally modifying a lateral distance of the phantom side and angular shock absorbers of the rear half of the phantom damping system according to the absolute value of the slip angle of the vehicle body and the slipping state, such that, when the vehicle is in the understeering state, the modification factor for the lateral distance of the rear half of the phantom damping system is generally increased according to an increase of the absolute value of the slip angle.

7. A device according to claim 2, wherein the calculating means further calculate a slip angle and a change rate of the slip angle of the vehicle body, thereby discriminating a slipping state of the vehicle about at least a dissipating state, and further calculate modification factors for proportionally modifying lateral distances of the phantom side and angular shock absorbers of the front and rear halves of the phantom damping system according to the absolute value of the slip angle of the vehicle body and the slipping state, such that, when the vehicle is in the dissipating state, the modification factors for the lateral distances of the front and rear halves of the phantom damping system are magnified to be larger than 1 and are further generally increased according to an increase of the absolute value of the slip angle.

8. A device according to claim 2, wherein the calculating means calculate a basic value of the first phantom damping coefficient of the phantom side shock absorber of the front half of the phantom damping system based upon a mean value of vertical accelerations of the portions of the vehicle body corresponding to the front left and front right wheels by looking at a map prepared therefor, and a basic value of the first phantom damping coefficient of the phantom side shock absorber of the rear half of the phantom damping system based upon a mean value of vertical accelerations of the portions of the vehicle body corresponding to the rear left and rear right wheels by looking at a map prepared therefor, and a basic value of the second phantom damping coefficient of the phantom angular shock absorber of the front half of the phantom damping system based upon a rotational acceleration of a mass of a front portion of the vehicle body corresponding to the front left and front right wheels by looking at a map prepared therefor, and a basic value of the second phantom damping coefficient of the phantom angular shock absorber of the rear half of the phantom damping system based upon a rotational acceleration of a mass of a rear portion of the vehicle body corresponding to the rear left and rear right wheels by looking at a map prepared therefor.

9. A device according to claim 8, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the first phantom damping coefficients of the front and rear halves of the phantom side shock absorbers according to a rate of throttle opening, such that the throttle opening rate dependent modification amounts for the front and rear halves are generally increased according to an increase of the throttle opening rate, the modification amount for the front half being more increased than the modification amount for the rear half.

10. A device according to claim 9, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the second phantom damping coefficients of the front and rear halves of the phantom angular shock absorbers according to the throttle opening rate, such that the throttle opening rate dependent modification amounts for the front and rear halves are generally increased according to an increase of the throttle opening rate, the modification amount for the front half being more increased than the modification amount for the rear half.

11. A device according to claim 8, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the first and second phantom damping coefficients and standard lateral distances of the front and rear halves of the phantom side and angular shock absorbers according to a deviation of a yaw rate of the vehicle from a standard yaw rate thereof theoretically calculatable from a steering angle and a vehicle speed, such that the yaw rate dependent modification amounts for the front and rear halves are generally increased in the absolute values thereof according to an increase in the absolute value of the yaw rate deviation, the sign of the yaw rate dependent modification amounts being dependent on the sign of the yaw rate deviation such that the signs of the yaw rate dependent modification amounts are reversed according to a reversal of the sign of the yaw rate deviation.

12. A device according to claim 8, wherein the calculating means further calculate modification factors for modifying shares of the first and second phantom damping coefficients and lateral distances of the front and rear halves of the phantom side and angular shock absorbers between the front and rear halves according to a rate of throttle opening, such that the throttle opening rate dependent modification factors for the front half are smaller as vehicle speed is higher and are generally decreased according to an increase of the throttle opening rate, the decrease being larger as the vehicle speed is higher, when the vehicle is a front drive vehicle.

13. A device according to claim 8, wherein the calculating means further calculate modification factors for modifying shares of the first and second phantom damping coefficients and lateral distances of the front and rear halves of the phantom side and angular shock absorbers between the front and rear halves according to a rate of throttle opening, such that the throttle opening rate dependent modification factors for the front half are larger as vehicle speed is higher and are generally increased according to an increase of the throttle opening rate, the increase being larger as the vehicle speed is higher, when the vehicle is a rear drive vehicle.

14. A device according to claim 8, wherein the calculating means further calculate modification factors for modifying shares of the first and second phantom damping coefficients and lateral distances of the front and rear halves of the phantom side and angular shock absorbers between the front and rear halves according to a brake stroke, such that the brake stroke dependent modification factors for the front half are generally increased according to an increase of the brake stroke, the increase being larger as the vehicle speed is higher, when the vehicle is an ordinary type vehicle.

15. A device according to claim 8, wherein the calculating means further calculate modification factors for modifying shares of the first and second phantom damping coefficients and lateral distances of the front and rear halves of the phantom side and angular shock absorbers between the front and rear halves according to a brake stroke, such that the brake stroke dependent modification factors for the front half are generally decreased according to an increase of the brake stroke, the decrease being larger as the vehicle speed is higher, when the vehicle is a sports type vehicle.

16. A device according to claim 8, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the first phantom damping coefficients of the front and rear halves of the phantom side shock absorbers according to front and rear masses of the vehicle body corresponding to the front and rear wheels, such that the mass dependent modification amounts for the front and rear halves are generally increased according to an increase of the front and rear masses.

17. A device according to claim 16, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the second phantom damping coefficients of the front and rear halves of the phantom angular shock absorbers according to the front and rear masses, such that the mass dependent modification amounts for the front and rear halves are generally increased according to an increase of the front and rear masses.

18. A device according to claim 8, wherein the calculating means further calculate modification factors for proportionally modifying the basic values of the first phantom damping coefficients of the front and rear halves of the phantom side shock absorbers according to vertically stroking velocities of front and rear portions of the vehicle body corresponding to the front and rear wheels, such that the vertically stroking velocity dependent modification factors for the front and rear halves are generally increased according to an increase of the vertically stroking velocities.

19. A device according to claim 18, wherein the calculating means further calculate modification factors for proportionally modifying the basic values of the second phantom damping coefficients of the front and rear halves of the phantom angular shock absorbers according to the vertically stroking velocities, such that the vertically stroking velocity dependent modification factors for the front and rear halves are generally increased according to an increase of the vertically stroking velocities.

20. A device according to claim 8, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the first phantom damping coefficients of the front and rear halves of the phantom side shock absorbers according to front and rear flapping indexes indicating liabilities of the front and rear wheels to flap, such that the flapping index dependent modification amounts for the front and rear halves are generally increased according to an increase of the flapping indexes.

21. A device according to claim 20, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the second phantom damping coefficients of the front and rear halves of the phantom angular shock absorbers according to the flapping indexes, such that the flapping index dependent modification amounts for the front and rear halves are generally increased according to an increase of the flapping indexes.

22. A device according to claim 8, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the first phantom damping coefficients of the front and rear halves of the phantom side shock absorbers according to a brake stroke, such that the brake stroke dependent modification amounts for the front and rear halves are generally increased according to an increase of the brake stroke, the modification amount for the front half being more increased than the modification amount for the rear half.

23. A device according to claim 22, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the second phantom damping coefficients of the front and rear halves of the phantom angular shock absorbers according to the brake stroke, such that the brake stroke dependent modification amounts for the front and rear halves are generally increased according to an increase of the brake stroke, the modification amount for the front half being more increased than the modification amount for the rear half.

24. A device according to claim 8, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the first phantom damping coefficients of the front and rear halves of the phantom side shock absorbers according to front and rear swaying indexes indicating liabilities of front and rear portions of the vehicle body corresponding to the front and rear wheels to sway, such that the swaying index dependent modification amounts for the front and rear halves are generally increased according to an increase of the swaying indexes.

25. A device according to claim 24, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the second phantom damping coefficients of the front and rear halves of the phantom angular shock absorbers according to the swaying indexes, such that the swaying index dependent modification amounts for the front and rear halves are generally increased according to an increase of the swaying indexes.

26. A device according to claim 25, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the first phantom damping coefficients of the front and rear halves of the phantom side shock absorbers according to front and rear flapping indexes indicating liabilities of the front and rear wheels to flap, such that the flapping index dependent modification amounts for the front and rear halves are generally increased according to an increase of the flapping indexes, and modification amounts for additively modifying the basic values of the second phantom damping coefficients of the front and rear halves of the phantom angular shock absorbers according to the flapping indexes, such that the flapping index dependent modification amounts for the front and rear halves are generally increased according to an increase of the flapping indexes, and then further select either the swaying index dependent modification amounts or the flapping index dependent modification amounts which are larger than the other as a whole for additively modifying the basic values of the first and second phantom damping coefficients.

27. A device according to claim 26, wherein the calculating means further calculate modification amounts for subtractively modifying the basic values of the first phantom damping coefficients of the front and rear halves of the phantom side shock absorbers according to front and rear rattling indexes indicating liabilities of front and rear portions of the vehicle body corresponding to the front and rear wheels to rattle, such that the rattling index dependent modification amounts for the front and rear halves are generally increased in the absolute values thereof according to an increase of the rattling indexes, and modification amounts for subtractively modifying the basic values of the second phantom damping coefficients of the front and rear halves of the phantom angular shock absorbers according to the rattling indexes, such that the rattling index dependent modification amounts for the front and rear halves are generally increased in the absolute values thereof according to an increase of the rattling indexes, and then further select either the selected swaying index dependent or flapping index dependent modification amounts or the rattling index dependent modification amounts which are larger than the other as a whole in the absolute values thereof for additively or subtractively modifying the basic values of the first and second phantom damping coefficients.

28. A device according to claim 8, wherein the calculating means further calculate modification amounts for subtractively modifying the basic values of the first phantom damping coefficients of the front and rear halves of the phantom side shock absorbers according to front and rear rattling indexes indicating liabilities of front and rear portions of the vehicle body corresponding to the front and rear wheels to rattle, such that the rattling index dependent modification amounts for the front and rear halves are generally increased in the absolute values thereof according to an increase of the rattling indexes.

29. A device according to claim 28, wherein the calculating means further calculate modification amounts for subtractively modifying the basic values of the second phantom damping coefficients of the front and rear halves of the phantom angular shock absorbers according to the rattling indexes, such that the rattling index dependent modification amounts for the front and rear halves are generally increased in the absolute values thereof according to an increase of the rattling indexes.

30. A device according to claim 1, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the first and second phantom damping coefficients the phantom side and angular shock absorbers when a maximum difference between leftward and rightward steering angles during a half of a cycle period of a consonant rolling of the vehicle body exceeds a threshold value predetermined therefor.

31. A device according to claim 1, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the first and second phantom damping coefficients of the phantom side and angular shock absorbers when a maximum difference between leftward and rightward lateral accelerations of the vehicle body during a half of a cycle period of a consonant rolling of the vehicle body exceeds a threshold value predetermined therefor.

32. A device according to claim 1, wherein the calculating means further calculate modification amounts for additively modifying the basic values of the first and second phantom damping coefficients of the phantom side and angular shock absorbers when a maximum difference between clockwise and counter-clockwise rolling accelerations of the vehicle body as viewed from the back of the vehicle during a half of a cycle period of a consonant rolling of the vehicle body exceeds a threshold value predetermined therefor.