Method and system for controlling a dual mode vehicle suspension system

• US 20060284387A1
• Filed: 06/16/2005
• Published: 12/21/2006
• Est. Priority Date: 06/16/2005
• Status: Active Grant

• Current Assignee: FCA US LLC (Stellantis NV)
• Original Assignee: Chrysler LLC (Stellantis NV)
• Inventors: Klees, Gerard
• Granted Patent: US 7,380,800 B2
• Time in Patent Office: Days
• US Class Current: 280/5.519
• CPC Class Codes: B60G 17/0165 to an external condition, e.g. rough road surface, side wind
• CPC Class Codes: B60G 17/018 characterised by the use of a specific signal treatment or control method
• CPC Class Codes: B60G 2202/152 Pneumatic spring
• CPC Class Codes: B60G 2300/07 Off-road vehicles
• CPC Class Codes: B60G 2400/20 Speed
• CPC Class Codes: B60G 2400/252 vertical
• CPC Class Codes: B60G 2600/02 Retarders, delaying means, dead zones, threshold values, cut-off frequency, timer interruption
• CPC Class Codes: B60G 2600/12 Sampling or average detecting; Addition or substraction

Abstract

A method and system for controlling a vehicle suspension system switchable between two modes of operation, including a first mode for when the vehicle is experiencing an on-road driving condition and a second mode for when the vehicle is experiencing an off-road driving condition, includes a vehicle speed sensor for sensing a speed of the vehicle and generating a vehicle speed signal, which may be an inherent part of the vehicle required for other vehicle functions, such as ABS, speed, or other control. The system also includes a controller for detecting an off-road driving condition and comparing the vehicle speed signal to a predetermined speed threshold. The controller then controls the suspension system to switch to the second mode of operation upon detecting the off-road driving condition and the vehicle speed signal being less than the predetermined speed threshold.

Claims

1. A method for controlling a suspension system of a vehicle having a plurality of wheels including left and right front wheels and left and right rear wheels, the suspension system switchable between two modes of operation, including a first mode for when the vehicle is experiencing an on-road driving condition and a second mode for when the vehicle is experiencing an off-road driving condition, the method comprising:

sensing a speed of the vehicle and generating a vehicle speed signal;

detecting an off-road driving condition;

comparing the vehicle speed signal to a predetermined speed threshold; and

controlling the suspension system to switch to the second mode of operation upon detecting the off-road driving condition and the vehicle speed signal being less than the predetermined speed threshold.

2. The method as recited in claim 1 wherein controlling the suspension system to switch to the second mode of operation further comprises determining if the off-road driving condition occurs for more than a predetermined amount of time.

3. The method as recited in claim 1 wherein detecting the off-road driving condition comprises:

sensing a front displacement for each of the front wheels;

sensing a rear displacement for each of the rear wheels;

determining whether the front displacements of the front wheels are out of phase with the rear displacements of the rear wheels; and

detecting the off-road driving condition based on the front and rear displacements of the front and rear wheels, respectively, and the front displacements being out of phase with the rear displacements.

4. The method as recited in claim 3 wherein detecting the off-road driving condition based on the front and rear displacements of the front and rear wheels, respectively, further comprises:

determining a front relative displacement between the front displacements;

determining a rear relative displacement between the rear displacements;

determining if the front relative displacement exceeds a predetermined displacement threshold; and

determining if the rear relative displacement of exceeds the predetermined displacement threshold.

5. The method as recited in claim 1 further comprising:

sensing a predetermined event; and

controlling the suspension system to switch to the first mode of operation upon detecting the predetermined event.

6. The method as recited in claim 5 wherein the predetermined event is ignition off.

7. The method as recited in claim 5 wherein the predetermined event occurs when the vehicle speed signal exceeds the predetermined speed threshold.

8. A system for controlling a suspension system of a vehicle having a plurality of wheels including left and right front wheels and left and right rear wheels, the suspension system switchable between two modes of operation, including a first mode for when the vehicle is experiencing an on-road driving condition and a second mode for when the vehicle is experiencing an off-road driving condition, the system comprising:

a vehicle speed sensor for sensing a speed of the vehicle and generating a vehicle speed signal; and

a controller operative to;

detect an off-road driving condition,

compare the vehicle speed signal to a predetermined speed threshold, and

control the suspension system to switch to the second mode of operation upon detecting the off-road driving condition and the vehicle speed signal being less than the predetermined speed threshold.

9. The system as recited in claim 8 wherein the controller, in controlling the suspension system to switch to the second mode of operation, is further operative to determine if the off-road driving condition occurs for more than a predetermined amount of time.

10. The system as recited in claim 8 further comprising:

a height sensor coupled to each of the wheels for sensing a front displacement of each of the front wheels and a rear displacement for each of the rear wheels; and

the controller, detecting the off-road driving condition, is further operative to;

determine whether the front displacements of the front wheels are out of phase with the rear displacements of the rear wheels; and

detect the off-road driving condition based on the front and rear displacements of the front and rear wheels, respectively, and the front displacements being out of phase with the rear displacements.

11. The system as recited in claim 10 wherein the controller, in detecting the off-road driving condition based on the front and rear displacements of the front and rear wheels, respectively, is further operative to:

determine a front relative displacement between the front displacements;

determine a rear relative displacement between the rear displacements;

determine if the front relative displacement exceeds a predetermined displacement threshold; and

determine if the rear relative displacement of exceeds the predetermined displacement threshold.

12. The system as recited in claim 8 wherein the controller is further operative to:

sense a predetermined event; and

control the suspension system to switch to the first mode of operation upon detecting the predetermined event.

13. The system as recited in claim 12 wherein the predetermined event is ignition off.

14. The system as recited in claim 12 wherein predetermined event occurs when the vehicle speed signal exceeds the predetermined speed threshold.