Patent Publication Number: US-2019168565-A1

Title: Pneumatic anti-roll system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of and priority to U.S. Patent Application No. 62/378,081, filed Aug. 22, 2016, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     This patent application is directed to vehicle suspension and, more specifically, to anti-roll systems. 
     BACKGROUND 
     A typical mechanical anti-roll bar or sway bar is a torsion spring connected between the left and right sides of a vehicle&#39;s suspension. The anti-roll bar acts independently of the main suspension springs. As one side of the suspension moves, the anti-roll bar tends to force the opposite side of the suspension, via the torsion spring, to move in the same direction. Thus, the anti-roll bar increases the vehicle suspension&#39;s roll stiffness, which increases the vehicle&#39;s resistance to rolling in turns. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the pneumatic anti-roll system introduced herein may be better understood by referring to the following Detailed Description in conjunction with the accompanying drawings, in which like reference numerals indicate identical or functionally similar elements: 
         FIG. 1  is a side view in elevation of a representative semi-trailer truck. 
         FIG. 2  is a schematic representation of a conventional air ride suspension height control system. 
         FIG. 3  is a schematic representation of a pneumatic anti-roll system according to a representative embodiment. 
         FIG. 4  is an enlarged view of a height control valve shown in  FIG. 3 . 
         FIG. 5  is a rear view of the semi-trailer shown in  FIG. 1 . 
         FIG. 6  is an isometric view of a double wishbone independent trailer suspension. 
         FIG. 7  is an end view of the suspension shown in  FIG. 6 . 
         FIG. 8  is a schematic representation of a pneumatic anti-roll system according to another representative embodiment. 
     
    
    
     The headings provided herein are for convenience only and do not necessarily affect the scope or meaning of the claimed embodiments. Further, the drawings have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be expanded or reduced to help improve the understanding of the embodiments. Moreover, while the disclosed technology is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the embodiments described. On the contrary, the embodiments are intended to cover all modifications, equivalents, and alternatives falling within the scope of the embodiments as defined by the appended claims. 
     DETAILED DESCRIPTION 
     Overview 
     A pneumatic anti-roll system for use on a vehicle suspension is disclosed. The pneumatic anti-roll system reduces the impact of lateral load transfer on a vehicle, such as a trailer, improving vehicle handling and control and decreasing tire wear under normal driving conditions. In heavy trucks and trailers an air ride suspension uses air springs as the main springs of the suspension. The disclosed pneumatic anti-roll system leverages these air springs to achieve the desired anti-roll performance but without the need to add the extra weight and complexity of a torsional spring (e.g., anti-roll bar). 
     In an embodiment, the pneumatic anti-roll system includes left and right side air springs connectable between a chassis of the vehicle and an axle of the vehicle suspension. Left and right side height control valves are mounted to the chassis and left and right side linkages connect between the left and right side height control valves and corresponding left and right end portions of the axle. Left and right side control air lines connect between the left and right side height control valves and the corresponding left and right side air springs, respectively. 
     General Description 
     Various examples of the device and systems introduced above will now be described in further detail. The following description provides specific details for a thorough understanding and enabling description of these examples. One skilled in the relevant art will understand, however, that the techniques discussed herein may be practiced without many of these details. Likewise, one skilled in the relevant art will also understand that the technology can include many other features not described in detail herein. Additionally, some well-known structures or functions may not be shown or described in detail below so as to avoid unnecessarily obscuring the relevant description. 
     The terminology used below is to be interpreted in its broadest reasonable manner, even though it is being used in conjunction with a detailed description of some specific examples of the embodiments. Indeed, some terms may even be emphasized below; however, any terminology intended to be interpreted in any restricted manner will be overtly and specifically defined as such in this section. 
       FIG. 1  illustrates a typical semi-trailer truck  10  including a tractor unit  12  connected to a semi-trailer  14 . Semi-trailer  14  includes a tandem axle suspension  16  having two axles  18 . Typically, each axle  18  includes four wheels  20 . With further reference to  FIG. 2 , a conventional tandem axle suspension  16  includes a pneumatic height control system  24 . The pneumatic height control system  24  includes an air supply e.g., air-tank  30 , a height control valve  26 , and four air springs  22 . Each axle  18  is supported on both ends by a corresponding air spring  22 . 
     The height control valve  26  is used to adjust the ride height of the semi-trailer  14  in response to varying loads by changing the air pressure in the air springs  22 . The height control valve  26  is mounted on the trailer chassis and the valve lever  28  is connected to the middle of one of the axles  18 . When the trailer  14  is at the desired ride height, the lever  28  is approximately level and the valve is “CLOSED”. If additional weight is added to the trailer  14 , the air springs  22  will be compressed under the added load consequently reducing the ride height. This will push the lever  28  upward into the “INFLATE” position, opening the valve  26 , which adds compressed air from tank  30  to all four of the air springs  22  until the air springs  22  are sufficiently inflated to restore the correct ride height. If the additional weight is removed from the trailer  14 , the air springs  22  will extend, consequently increasing the trailer&#39;s ride height above the desired height. This will, in turn, move the lever  28  downward into the “EXHAUST” position, which allows compressed air to escape from the air springs  22 , thereby reducing the ride height until the desired height is restored. 
     In the pneumatic anti-roll system  100  shown in  FIG. 3 , multiple height control valves are used to control the ride height of the trailer  14  as well as compensate for asymmetric loading due to cornering. One particular embodiment uses a pair of valves  126   L  and  126   R , for the left and right sides of the trailer  14 . By separating the pressure control of the left  122   L  and right  122   R  side air springs it is possible to adjust for asymmetric loading on the trailer due to weight transfer under cornering or due to uneven loading of cargo in the trailer. 
     The pneumatic anti-roll system  100  includes an air supply e.g., air-tank  130  connected to the left and right side height control valves  126   L  and  126   R  via supply line  136 . As shown in  FIG. 4 , each height control valve  126   L  and  126   R  is connected to a control line to selectively supply air to the air springs from air-tank  130  and vent pressure from the air springs through an exhaust. For example, height control valve  126   L  is operative to supply air pressure from air-tank  130  to left side air springs  122   L  via control line  140   L  and to vent excess pressure from air springs  122   L  through exhaust  138   L . Returning to  FIG. 3 , each height control valve  126   L  and  126   R  is mounted to the trailer chassis with a corresponding bracket, such as left side valve bracket  134   L . Each height control valve  126   L  and  126   R  also includes a corresponding valve lever  128   L  and  128   R  connected the left and right ends of axle  18  via linkages  132   L  and  132   R , respectively (also see  FIG. 5 ). 
     When trailer  14  rounds a right-hand corner as shown in  FIG. 5 , the left end portion of the axle  18  moves upward toward the chassis whereby the outside (i.e., left) air springs  122   L  are compressed; locally reducing the ride height, thereby opening the height control valve  126   L  so that extra compressed air will be added to left-side air springs  122   L . On the inside of the turn (i.e., right), air springs  122   R  are extended; locally increasing the ride height, whereby the height control valve  126   R  exhausts compressed air from the right-side air springs  122   R . Adding air to the left-side air springs  122   L  and exhausting air pressure from right-side air springs  122   R  acts to push back against the lateral loading created by cornering such that the trailer tends to remain level and body roll of the trailer is reduced. 
     In situations of asymmetric loadings caused by single wheel loading due to the bumps in the road such as a pothole, the responsiveness of the system is slow enough that it will not impact the pressure in any of the air springs. However, when cornering, the resulting asymmetric loading created by the lateral loading, is held long enough that the system is able to respond. 
     The pneumatic anti-roll system described herein provides the desired functionality of a mechanical anti-roll bar but without the added weight and complexity because it uses the existing air springs of the main suspension. This also means that as the overall weight of the vehicle is increased the pneumatic system is easily able to adapt to the increased load of extra cargo. This is not possible with a mechanical torsion spring, which would be sized for the gross weight of the vehicle. Thus, it would be over sized for all but the heaviest loading conditions. The pneumatic based system also lends itself to computer control or activation and can be adapted for an active suspension system. In some embodiments, the responsiveness of the system can be tuned by altering the sizing of the valving in order to control fill rates and exhaust rates. In some embodiments, the mechanical valving could be replaced by a computer control system so that this system could become part of an active suspension control system. In another representative embodiment, the system can use height control valves for each wheel. Accordingly, a tandem axle system would have four valves, for example. 
     Although the pneumatic anti-roll system has been described with respect to conventional tandem solid axle trailer suspensions, the disclosed technology can be applied to single axle suspensions or suspensions with more than two axles. Furthermore, the pneumatic anti-roll system can be applied to other suspension system configurations incorporating air springs. For example, the pneumatic anti-roll system can be applied to the double wishbone independent trailer suspension  200  shown in  FIGS. 6 and 7 . The double wishbone suspension  200  includes a sub-frame  202  supporting multiple wheel spindles  204 . Each spindle  204  is suspended on upper  208  and lower  206  wishbone control arms. Multiple air springs  210  are positioned between the upper control arm  208  and the sub-frame  202  to support the weight of the trailer. A shock absorber  212  (e.g., damper) is connected between the lower control arm  206  and the sub-frame  202  to help control movement of the suspension. In at least one embodiment, the height control valves of the pneumatic anti-roll system are mounted to the sub-frame  202  and linkages connect the valve lever to the upper or lower control arms to actuate the height control valve. The double wishbone suspension is further described in co-pending U.S. Patent Application No. 62/378,077 (Attorney Docket No. 89143-8080.US00), filed Aug. 22, 2016, entitled DOUBLE WISHBONE INDEPENDENT TRAILER SUSPENSION, the disclosure of which is incorporated herein by reference in its entirety. 
       FIG. 8  illustrates a pneumatic anti-roll system  300  according to another representative embodiment. The pneumatic anti-roll system  300  includes a set of electronic micro-computer controlled pneumatic valves  326 . Built into each air spring  322  is a non-contact height sensor  323 , a device that is able to measure the distance between the upper  342  and lower  344  mount plates of the air spring  322 . The height sensors  323  output electrical signals to a small micro-computer  350  which uses these signals to determine the ride height of the vehicle at each wheel. If the micro-computer  350  senses that a wheel end is no longer at a predetermined nominal ride height it is then able to adjust the air pressure in a given air spring by operating the corresponding valve  326  to either supply more air pressure from tank  330  to the air spring  322  or exhaust air pressure from the air spring  322  through an exhaust outlet  346 . In some embodiments, the predetermined nominal ride height comprises a range of acceptable ride heights, such as a nominal ride height plus or minus a tolerance, for example and without limitation ±0.25 inches. Some examples of suitable air springs with non-contact height sensors are further described in U.S. Pat. No. 9,694,640, filed Apr. 9, 2014, entitled NON-CONTACT POWER SUPPLY FOR HEIGHT SENSOR WITH SINGLE CABLE, the disclosure of which is incorporated herein by reference in its entirety. 
     This system offers a number of advantages. For example, the height sensor  323  is located inside the air spring  322  and thus is protected from the weather, dirt, and other contaminants. The pneumatic control valves  326  can also be positioned so that they are not exposed to contamination or weather. The system is micro-computer controlled and so the responsiveness of the system and the control algorithm used to determine the roll control of the vehicle can be easily adjusted through software changes. 
     Remarks 
     The above description and drawings are illustrative and are not to be construed as limiting. Numerous specific details are described to provide a thorough understanding of the disclosure. However, in some instances, well-known details are not described in order to avoid obscuring the description. Further, various modifications may be made without deviating from the scope of the embodiments. Accordingly, the embodiments are not limited except as by the appended claims. 
     Reference in this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Moreover, various features are described which may be exhibited by some embodiments and not by others. Similarly, various requirements are described which may be requirements for some embodiments but not for other embodiments. 
     The terms used in this specification generally have their ordinary meanings in the art, within the context of the disclosure, and in the specific context where each term is used. It will be appreciated that the same thing can be said in more than one way. Consequently, alternative language and synonyms may be used for any one or more of the terms discussed herein, and any special significance is not to be placed upon whether or not a term is elaborated or discussed herein. Synonyms for some terms are provided. A recital of one or more synonyms does not exclude the use of other synonyms. The use of examples anywhere in this specification, including examples of any term discussed herein, is illustrative only and is not intended to further limit the scope and meaning of the disclosure or of any exemplified term. Likewise, the disclosure is not limited to various embodiments given in this specification. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. In the case of conflict, the present document, including definitions, will control.