Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
1999-04-01
2001-01-30
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C701S072000, C280S005512, C280S005515
Reexamination Certificate
active
06181997
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates to a vehicle suspension control system and method.
BACKGROUND OF THE INVENTION
Some automotive vehicles are equipped with vehicle dynamic stability controls that apply braking force at specific corners of the vehicle to initiate changes in vehicle yaw rate. But the application of a braking force at a specific corner also creates a body pitch motion at that corner that can cause a tilting motion of the vehicle body around a diagonal axis. For example, in order to reverse an excessive yaw rate to the right, the stability control may apply a braking force at the left front corner of the vehicle, or a greater braking force at the left front corner than at the right front corner. But this also produces a downward pitch of the left front corner of the vehicle and a reacting upward pitch of the right rear corner of the vehicle that essentially create a tilting motion of the body about a diagonal axis with the left front corner of the vehicle dipping and the right rear of the vehicle rising. A similar movement, with the right front corner dipping and the left rear corner rising, tends to result from application of a greater braking force to the vehicle brake at the front right corner to initiate a vehicle yaw rate change in the opposite direction. Such body movement may be undesirable to occupants of the vehicle.
Many automotive vehicles have suspensions that vary damping force in response to control commands determined by a computer controller, in order to improve overall vehicle ride comfort and handling. Such systems are generally responsive to vehicle body motions to reduce the diagonal body tilting motion described above, but such general response requires the undesirable body motion to occur and be sensed before the system can react to it. In addition, since the cause of the undesirable body motion is not known by such a system, the response must be general in nature and may not be optimal for the specific dynamic situation.
It is also known in the art to provide a signal indicating activation of a vehicle brake pedal or braking system generally to provide immediate stiffening of both front suspension dampers so as to minimize brake induced vehicle pitch (dive). But such systems do not optimally control a pitch on only one side, with a resulting tilting of the vehicle body around a diagonal axis.
SUMMARY OF THE INVENTION
This invention adapts a variable damping suspension to be responsive to a specific active brake signal from a vehicle braking control that is applying a greater braking force to one front corner than the other to affect vehicle yaw rate so as to optimally control pitch at the one front corner and the diagonally opposed rear corner and thus the resulting tilting motion of the vehicle body about a diagonal axis.
More specifically, a vehicle suspension system is responsive to an active brake signal from a brake system indicating the application of a greater braking force to one front corner brake than to the other front corner brake to affect vehicle yaw rate. The vehicle suspension system determines the relative velocities of the front corner suspension adjacent the front corner brake receiving the greater braking force and the diagonally opposed rear corner suspension and further determines a compression damping command for the front corner suspension and a rebound damping command for the rear corner suspension. While the active brake signal is present, the suspension control applies the compression damping command for the front corner suspension when its relative velocity indicates that it is in compression and applies the rebound damping command for the rear corner suspension when its relative indicates that it is in rebound.
In a preferred embodiment, the control also derives demand force commands for dampers at each corner of the vehicle from relative velocity signals at the corners of the vehicle and applies the demand force command to each damper only when a comparison of the direction of the demand force command for a damper with the sensed relative velocity of the damper indicates that a force corresponding to the demand force command can be effectively exerted by the damper. But the compression and rebound damping commands are applied to the appropriate dampers according to the direction of relative velocity only, without regard to the direction of the demand force command for the corner.
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Badenoch Scott Wilson
Connair Karen Marie
Fratini Albert Victor
Hamilton Harold David
Shal David Andrew
Arthur Gertrude
Cuchlinski Jr. William A.
Delphi Technologies Inc.
Sigler Robert M.
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