VEHICLE SUSPENSION SYSTEM AND METHOD OF OPERATING SAME

• US 20080228352A1
• Filed: 03/12/2008
• Published: 09/18/2008
• Est. Priority Date: 03/12/2007
• Status: Active Grant

• Current Assignee: Driveright Holdings, Ltd.
• Original Assignee: BFS Diversified Products LLC (Bridgestone Corporation)
• Inventors: Bounds, Joseph A, Holbrook, Gregory A, Brookes, Graham R
• Granted Patent: US 7,957,865 B2
• Time in Patent Office: Days
• US Class Current: 701/37
• CPC Class Codes: B60G 17/0155 pneumatic unit
• 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 17/019 characterised by the type of sensor or the arrangement thereof B60G17/01941 takes precedence
• CPC Class Codes: B60G 21/10 not permanently interconnected, e.g. operative only on acceleration, only on deceleration or only at off-straight position of steering
• CPC Class Codes: B60G 2202/152 Pneumatic spring
• CPC Class Codes: B60G 2204/80 Interactive suspensions; arrangement affecting more than one suspension unit
• CPC Class Codes: B60G 2300/0262 Multi-axle trucks
• CPC Class Codes: B60G 2400/252 vertical
• CPC Class Codes: B60G 2500/30 Height or ground clearance
• CPC Class Codes: B60G 2600/02 Retarders, delaying means, dead zones, threshold values, cut-off frequency, timer interruption
• CPC Class Codes: B60G 2600/07 Inhibiting means
• CPC Class Codes: B60G 2600/12 Sampling or average detecting; Addition or substraction
• CPC Class Codes: B60G 2800/912 Attitude Control; levelling control
• CPC Class Codes: B60G 2800/914 Height Control System

Abstract

A suspension system for use on a vehicle having two or more rear axles. The suspension system includes a plurality of gas springs and plurality of height sensors capable of outputting signals having a relation to distances between the respective ends of the respective first and second rear axles and the sprung mass of the vehicle. A control system adapted to selectively inflate or deflate respective ones of the plurality of gas springs to thereby adjust a leveled orientation of the sprung mass. The control system includes a controller that is adapted to determine a rear axle vertical offset and a rear axle articulation offset. The controller is adapted to determine whether conditions are appropriate for adjusting the suspension system by comparing the rear axle vertical offset and/or the rear axle articulation offset to a corresponding vertical offset threshold and/or an articulation offset threshold. A method is also included.

Claims

1. A suspension system capable of supporting an associated sprung mass on an associated unsprung mass of an associated vehicle having a longitudinally extending midline and left and right sides relative to the midline, the associated unsprung mass including a front axle, a first rear axle and a second rear axle, said suspension system comprising:

a first left gas spring and a first right gas spring respectively disposed along left-side and right-side portions of the first rear axle;

a second left gas spring and a second right gas spring respectively disposed along left-side and right-side portions of the second rear axle;

a pressurized gas system including a pressurized gas source adapted to provide pressurized gas and a control device capable of selectively placing said gas springs in fluid communication with one of said pressurized gas source and a pressurized gas exhaust;

a first set of height sensors capable of outputting signals having a relation to relative distances between the first rear axle and the associated sprung mass, said first set of height sensors including a first left height sensor operatively connected along the left-side portion of the first rear axle and a first right height sensor operatively connected along the right-side portion of the first rear axle;

a second set of height sensors capable of outputting signals having a relation to relative distances between the second rear axle and the associated sprung mass, said second set of height sensors including a second left height sensor operatively connected along the left-side portion of the second rear axle and a second right height sensor operatively connected along the right-side portion of the second rear axle; and

,

a controller operatively connected to said first and second sets of height sensors for receiving said signals therefrom and operatively connected to said control device for selectively inflating or deflating respective ones of said gas springs to thereby adjust a leveled orientation of the associated sprung mass, said controller storing a vertical offset threshold and an articulation offset threshold, and said controller adapted to;

determine one or more relative distances between the associated sprung mass and at least one of the first and second rear axles based on said signals from at least a corresponding one of said first and second sets of height sensors;

determine that a condition exists for adjusting said leveled orientation of the associated sprung mass based at least in part on said one or more relative distances;

calculate a first rear axle to second rear axle vertical offset (RAVO) and a first rear axle to second rear axle articulation offset (RAAO) based at least in part on said one or more relative distances;

compare said RAVO to said vertical offset threshold and compare said RAAO to said articulation offset threshold; and

,

upon determining that both of said RAVO and said RAAO are less than said respective vertical and articulation offset thresholds, said controller adapted to actuate said control device to selectively inflate or deflate one or more of said gas springs and thereby adjust said leveled orientation of the associated sprung mass;

or,

upon determining that one of said RAVO and said RAAO is one of equal to or greater than a respective one of said vertical and articulation offset thresholds, said controller adapted to one of ignore said condition for adjusting said leveled orientation of the associated sprung mass and delay adjusting said leveled orientation of the associated sprung mass until both of said RAVO and said RAAO are less than said respective vertical and articulation offset thresholds.

2. A suspension system according to claim 1, wherein said second left gas spring is fluidically connected for selective fluid communication with said first left gas spring, and said second right gas spring is fluidically connected for selective fluid communication with said first right gas spring.

3. A suspension system according to claim 1 further comprising a third set of height sensors capable of outputting signals having a relation to relative distances between the front axle and the associated sprung mass, said third set of height sensors including a third left height sensor operatively connected along the left-side portion of the front axle and a third right height sensor operatively connected along the right-side portion of the front axle, and said controller adapted to determine one or more relative distances between the associated sprung mass and the front axle based on signals from said third set of height sensors.

4. A suspension system according to claim 3 further comprising a third left gas spring and a third right gas spring respectively disposed along left-side and right-side portions of the front axle.

5. A suspension system according to claim 3, wherein the controller is further adapted to:

store a front axle to rear axle articulation offset threshold;

calculate a front axle to first rear axle articulation offset (FRAAO) based at least in part on said one or more relative distances;

compare said FRAAO to said front to rear axle articulation offset threshold; and

,

upon determining that said FRAAO is less than said front to rear axle articulation offset threshold, said controller adapted to adjust said leveled orientation of the associated sprung mass by actuating said control device to selectively inflate or deflate one or more of said gas springs;

or,

upon determining that said FRAAO is one of equal to or greater than said front to rear axle articulation offset threshold, said controller adapted to one of ignore said condition for adjusting said leveled orientation of the associated sprung mass and delay adjusting said leveled orientation of the associated sprung mass until each of said RAVO, said RAAO and said FRAAO is less than said respective vertical offset threshold, said articulation offset threshold and said front to rear axle articulation offset threshold.

6. A suspension system according to claim 5, wherein at least one of said vertical offset threshold, said articulation offset threshold and said front to rear axle articulation offset threshold is variable based at least in part on one or more of a speed of the associated vehicle, a load of the associated sprung mass, and an ambient temperature of an associated environment of the associated vehicle.

7. A suspension system according to claim 3, wherein said controller is adapted to determine that said condition exists for adjusting said leveled orientation based at least in part on said one or more relative distances between the associated sprung mass and the front axle.

8. A suspension system according to claim 7, wherein the controller is further adapted to calculate a left-side rear axle height average (LSA) and a right-side rear axle height average (RSA) based at least in part on said one or more relative distances.

9. A suspension system according to claim 8, wherein said controller is adapted to calculate said FRAAO based at least in part on said LSA and said RSA.

10. A suspension system according to claim 9, wherein the controller is further adapted to:

store a LSA target height and a RSA target height; and

upon determining that each of said RAVO, said RAAO and said FRAAO is less than said respective vertical offset threshold, said articulation offset threshold and said front to rear axle articulation offset threshold, said controller adapted to actuate said control device to selectively inflate or deflate one or more of said gas springs until said LSA and said RSA approximately reach said LSA and said RSA target heights.

11. A method of operating a suspension system capable supporting a sprung mass of a vehicle on an unsprung mass thereof, the vehicle having a longitudinally-extending midline with left and right sides established relative to the midline, and the unsprung mass including a front axle, a first rear axle and a second rear axle each having left-side and right-side portions, said method comprising:

a) providing a controller capable of controlling performance of a leveling action for adjusting a leveled orientation of the sprung mass relative to the unsprung mass, and said controller storing a vertical offset threshold and an articulation offset threshold;

b) determining a first left height (FLH) between the sprung mass and the left-side portion of the first rear axle, a first right height (FRH) between the sprung mass and the right-side portion of the first rear axle, a second left height (SLH) between the sprung mass and the left-side portion of the second rear axle, and a second right height (SRH) between the sprung mass and the right-side portion of the second rear axle;

c) determining based on at least one of said first left height, said first right height, said second left height and said second right height that a condition exists for initiating a leveling action to adjust the leveled orientation of the sprung mass of the vehicle;

d) calculating at least one of a first rear axle to second rear axle vertical offset (RAVO) and first rear axle to second rear axle articulation offset (RAAO);

e) comparing said at least one of said RAVO and said RAAO with a corresponding one of said vertical offset threshold and said articulation offset threshold; and

,

f) if at least one of said RAVO and said RAAO is equal to or greater than said corresponding one of said vertical offset threshold and said articulation offset threshold, one of;

f1) delaying initiation of a leveling action until each of said RAVO and said RAAO is less than said corresponding one of said vertical offset threshold and said articulation offset threshold; and

,

f2) ignoring said condition for initiating a leveling action;

or,

g) if each of said RAVO and said RAAO is less than said corresponding one of said vertical offset threshold and said articulation offset threshold, initiating a leveling action to adjust the leveled orientation of the sprung mass of the vehicle.

12. A method according to claim 11, wherein calculating at least one of said RAVO and said RAAO in d) includes calculating said RAVO using the relation:

13. A method according to claim 11, wherein calculating at least one of said RAVO and said RAAO in d) includes calculating said RAAO using the relation:

14. A method according to claim 11, wherein b) includes determining a third left height (TLH) between the sprung mass and the left-side portion of the front axle and includes determining a third right height (TRH) between the sprung mass and the right-side portion of the front axle, and c) include determining that a condition exists for initiating a leveling action based at least in part on said third left height and said third right height.

15. A method according to claim 11, wherein providing said controller in a) includes said controller storing a front axle to rear axle articulation offset threshold value, wherein b) includes determining a third left height (TLH) between the sprung mass and the left-side portion of the front axle and includes determining a third right height (TRH) between the sprung mass and the right-side portion of the front axle, and said method further comprises:

calculating a front axle to rear axle articulation offset (FRAAO) based at least in part on said third left height and said third right height;

comparing said FRAAO to said front axle to rear axle articulation offset threshold value; and

,

if said FRAAO is equal to or greater than said front axle to rear axle articulation offset threshold value then performing one of f1) and f2);

or,

if said FRAAO is less than said front axle to rear axle articulation offset threshold value then performing g).

16. A method according to claim 15, wherein calculating said FRAAO includes using the relation:

17. A method according to claim 15, wherein calculating FRAAO includes using the relation:

18. A method of controlling a suspension system capable of supporting a sprung mass on an unsprung mass of a vehicle that has a longitudinally-extending midline with left and right sides disposed relative to the midline, the unsprung mass including a front axle, a first rear axle and a second rear axle each having left-side and right-side portions, said method comprising:

providing a plurality of gas springs with one of said plurality of gas springs disposed along a different one of each of the left-side and right-side portions of each of the front axle, the first rear axle and the second rear axle;

providing a plurality of height sensors with one of said plurality of height sensors operatively connected between the sprung mass and a different one of each of the left-side and right-side portions of each of the front axle, the first rear axle and the second rear axle, said plurality of height sensors being capable of outputting signals having a relation to a respective distance between the sprung mass and a respective one of said axles;

providing a pressurized gas system including a pressurized gas source adapted to provide pressurized gas and a control device capable of selectively placing said gas springs in fluid communication with one of said pressurized gas source and a pressurized gas outlet;

providing a controller in communication with said plurality of height sensors for receiving height signals therefrom, and said controller in communication with said control device for selectively inflating and deflating respective ones of said gas springs to adjust a leveled orientation of the associated sprung mass;

programming a vertical offset threshold into said controller;

determining one or more relative distances between the sprung mass and one or more of the front axle, the first rear axle and the second rear axle based on said signals from said plurality of height sensors;

determining that a condition exists for adjusting said leveled orientation of the sprung mass based at least in part on said one or more relative distances;

calculating a first rear axle to second rear axle vertical offset (RAVO) based at least in part on one or more of said relative distances;

comparing said RAVO to said vertical offset threshold; and

,

permitting a leveling activity upon determining that said RAVO is less than said vertical offset threshold and actuating said control device to selectively inflate or deflate one or more of said gas springs;

or,

prohibiting said leveling activity upon determining that said RAVO is equal to or greater than said vertical offset threshold, and one of ignoring said condition for adjusting said leveled orientation of the associated sprung mass and waiting until said RAVO is less than said vertical offset threshold before initiating said leveling activity.

19. The method of claim 18 further comprising:

programming an articulation offset threshold into said controller;

calculating a first rear axle to second rear axle articulation offset (RAAO) based at least in part on one or more of said relative distances;

comparing said RAAO to said articulation offset threshold; and

,

permitting said leveling activity upon determining that both of said RAVO and said RAAO are less than said respective vertical and articulation offset thresholds and actuating said control device to selectively inflate or deflate one or more of said gas springs;

or,

prohibiting said leveling activity upon determining that said RAAO is equal to or greater than said articulation offset threshold, and one of ignoring said condition for adjusting said leveled orientation of the associated sprung mass and waiting until said RAAO is less than said articulation offset threshold before initiating said leveling activity.

20. The method of claim 19 further comprising:

programming a front axle to rear axle articulation offset threshold into said controller;

calculating a front axle to rear axles articulation offset (FRAAO) based at least in part on one or more of said relative distances;

comparing said FRAAO to said front to rear axle articulation offset threshold; and

,

permitting said leveling activity upon determining that said RAVO is less than said vertical offset threshold, said RAAO is less than said articulation offset threshold and said FRAAO is less than said front to rear axle articulation offset threshold, and actuating said control device to selectively inflate or deflate one or more of said gas springs;

or,

prohibiting said leveling activity upon determining that said FRAAO is equal to or greater than said front to rear axle articulation offset threshold, and one of ignoring said condition for adjusting said leveled orientation of the associated sprung mass and waiting until said FRAAO is less than said articulation offset threshold before initiating said leveling activity.