CLOSED LOOP PRESSURE CONTROL FOR DUAL AIR SPRING CONFIGURATION

• US 20100253017A1
• Filed: 04/01/2009
• Published: 10/07/2010
• Est. Priority Date: 04/01/2009
• Status: Active Grant

• Current Assignee: ArvinMeritor Technology LLC (Meritor, Inc. (Nevada))
• Original Assignee: ArvinMeritor Technology LLC (Meritor, Inc. (Nevada))
• Inventors: VanRaaphorst, David A.
• Granted Patent: US 8,899,603 B2
• Time in Patent Office: Days
• US Class Current: 280/5.504
• CPC Class Codes: B60G 17/0155 pneumatic unit
• 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 17/0485 the springs being pneumatic springs with a flexible wall, e.g. with levelling valves
• CPC Class Codes: B60G 17/0521 the spring having a flexible wall
• CPC Class Codes: B60G 2202/152 Pneumatic spring
• CPC Class Codes: B60G 2202/314 The spring being a pneumatic spring
• CPC Class Codes: B60G 2202/412 Pneumatic actuator
• CPC Class Codes: B60G 2400/252 vertical
• CPC Class Codes: B60G 2400/51 in suspension unit
• CPC Class Codes: B60G 2400/51222 Pneumatic
• CPC Class Codes: B60G 2500/202 Height or leveling valve for air-springs
• CPC Class Codes: B60G 2500/2041 for variable volume air springs, e.g. using accumulators as expansion chambers
• CPC Class Codes: B60G 2600/09 Feedback signal
• CPC Class Codes: B60G 2600/124 Error signal
• CPC Class Codes: B60G 2600/182 Active control means
• CPC Class Codes: B60G 2600/1877 Adaptive Control
• CPC Class Codes: B60G 2600/20 Manual control or setting means
• CPC Class Codes: B60G 2600/70 Computer memory; Data storage, e.g. maps for adaptive control
• CPC Class Codes: B60G 2800/012 Rolling condition
• CPC Class Codes: B60G 2800/014 Pitch; Nose dive
• CPC Class Codes: B60G 2800/162 : Reducing road induced vibrations
• CPC Class Codes: B60G 2800/702 : Improving accuracy of a sensor signal
• CPC Class Codes: B60G 2800/91 : Suspension Control
• CPC Class Codes: F16F 2230/08 : Sensor arrangement
• CPC Class Codes: F16F 9/057 : characterised by the piston

Abstract

An active air suspension system includes an air spring assembly that has a piston airbag and a primary airbag mounted around the piston airbag to provide a variable force and rate dual air spring configuration. The air suspension system is configured to accurately control pressure within the piston airbags in a closed-loop manner. Continuous control of the piston pressure provides an accurate increase or decrease of spring rate or force depending on the controller inputs.

Claims

1. An air suspension system comprising:

at least one air spring assembly including a piston airbag and a primary air bag mounted around said piston airbag;

at least one pressure sensor that continuously measures pressure within said piston airbag, said pressure sensor generating a pressure signal that corresponds to a measured pressure;

a valve assembly that controls air supply into and out of said piston airbag; and

a controller that receives said pressure signal as an input, compares this input to at least one desired piston airbag characteristic, and generates an output signal to modify pressure within said piston airbag if said input is different from said desired piston airbag characteristic.

2. The air suspension system according to claim 1 wherein said desired piston airbag characteristic comprises a desired piston airbag diameter to provide a desired spring stiffness.

3. The air suspension system according to claim 2 wherein said controller continuously receives pressure input signals from said pressure sensor indicating pressure changes within said piston airbag, and wherein said controller actively adjusts pressure within said piston airbag in response to the pressure changes to maintain said desired spring stiffness in a closed-loop manner.

4. The air suspension system according to claim 3 wherein said controller generates electric control signals to actively control said valve assembly to control air flow into and out of said piston airbag.

5. The air suspension system according to claim 2 wherein said at least one air spring assembly comprises a plurality of air spring assemblies each having one primary airbag and one associated piston airbag, said valve assembly comprises a separate valve assembly for each air spring assembly, and said at least one pressure sensor comprises a plurality of pressure sensors with one pressure sensor being associated with each piston airbag, and wherein said controller continuously receives pressure input signals from each of said pressure sensors indicating specific pressure changes within said associated piston airbag, and wherein said controller actively adjusts pressure within each of said piston airbags in response to the pressure changes to maintain said desired spring stiffness in a closed-loop manner.

6. The air suspension system according to claim 5 wherein said controller generates a plurality of control signals to control air supply into and out of each piston airbag independently of all other piston airbags.

7. The air suspension system according to claim 5 including at least one damper mounted to each air spring assembly.

8. The air suspension system according to claim 7 wherein said at least one damper comprises an electrically controlled shock absorber.

9. The air suspension system according to claim 5 wherein each of said separate valve assemblies includes an inlet valve and an outlet valve that are separate from each other and are controlled independently of each other.

10. The air suspension system according to claim 5 wherein said controller continuously adjusts spring force and spring rate of each of said air spring assemblies by individually controlling air flow into and out of each piston airbag and each primary airbag.

11. A method of controlling airflow within an air suspension system comprising the steps of:

(a) providing at least one air spring assembly including a piston airbag and a primary air bag mounted around the piston airbag, and providing a valve assembly that controls air supply into and out of the piston airbag;

(b) continuously measuring pressure within the piston airbag and generating a pressure signal that corresponds to a measured pressure; and

(c) receiving pressure signals from step (b) as an input, comparing this input to at least one desired piston airbag characteristic, and generating an output control signal to modify pressure within the piston airbag via the valve assembly if the input is different from the desired piston airbag characteristic.

12. The method according to claim 11 wherein the desired piston airbag characteristic comprises a desired piston airbag diameter to provide a desired spring stiffness.

13. The method according to claim 11 including continuously receiving pressure input signals from a pressure sensor indicating pressure changes within the piston airbag, and actively adjusting pressure within the piston airbag in response to the pressure changes to maintain the desired spring stiffness in a closed-loop manner.

14. The method according to claim 11 wherein the at least one air spring assembly comprises a plurality of air spring assemblies each having one primary airbag and one associated piston airbag, the valve assembly comprises a separate valve assembly for each air spring assembly, and including providing a plurality of pressure sensors with one pressure sensor being associated with each piston airbag, and including the steps of continuously receiving pressure input signals from each of the pressure sensors indicating specific pressure changes within the associated piston airbag, and actively adjusting pressure within each of the piston airbags in response to the pressure changes to maintain the desired spring stiffness for each air spring assembly in a closed-loop manner.