Abstract:
A suspension system for use with a frame comprising a first side suspension opposite a second side suspension, the first side suspension having a complete parallelogram suspension proximate the first side, and the second side suspension having a complete parallelogram suspension proximate the second side. The suspension system also includes a cross tube disposed at least partially between the first side and the second side, as well as at least one spring for resiliently controlling the vertical movement of the first and second side suspensions.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from U.S. Provisional Patent Application Ser. No. 61/170,885 filed Apr. 20, 2009; the disclosure of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    The invention relates generally to an improved vehicle suspension system. More particularly, the invention relates to air spring suspension systems with parallelogram components for land vehicles. Specifically, the invention relates to a parallelogram style suspension system with an independent, full parallelogram suspension at each wheel. 
         [0004]    2. Background Information 
         [0005]    Suspensions are available in the prior art which utilize air springs to provide a comfortable ride, even for large over-the-road trucks and other heavy vehicles. The air springs are typically used in industrial vehicle single axle units tandem or multi-axle arrangements of two or more axles which are either driven or non-driven. 
         [0006]    One drawback of air spring suspensions is that an air spring is essentially an air inflated bag and requires auxiliary stabilization. An air suspended axle must have separate independent mechanical location and attitude controls and stabilized components or it will not function. Absent stabilization, the air spring will extend to its maximum length or width in the direction of least resistance. Also, uneven transverse load distribution on a vehicle supported on unstable air springs will cause vehicle lean and tip-over. 
         [0007]    A significant number of air spring suspensions have been developed which to a greater or lesser extent, control axle location and attitude. A number of suspensions that have been developed are roll rigid, while others are roll flexible, each generally being designed for a specific application. The most common roll rigid configuration is the trailing beam type suspension, most of which use the axle as a torsion rod to provide roll rigidity. 
         [0008]    Another type of suspension which has been developed is the parallelogram suspension which is not inherently roll rigid, and does not inherently provide lateral stiffness. Again, ancillary devices such as an anti-roll bar, track bars, or guide mechanisms have been utilized to stabilize typical parallelogram designs. As such, parallelogram type suspensions, even with the ancillary devices attached, were often only suitable for low center of gravity loads, or on specialized vehicles stabilized by other vehicle suspension mechanisms. 
         [0009]    Trailing arm suspensions are brake reactive. That is, when the vehicle brakes are applied, the suspension will tend to compress thereby reducing the suspensions effectiveness. Similarly, when the brakes are applied as the vehicle moves in reverse, the suspension will tend to raise up, and pivot about the single trailing arm pivot, again reducing the suspensions effectiveness. Further, most trailing arm suspensions suffer from dock walk such that they move toward or away from the loading dock as the suspension moves up or down with the brakes locked. This movement is caused from air draining off the air springs, or as a result of loads added to or removed from the vehicle, or the temperature changes that occur as the trailer remains parked by the dock. Dock walk occurs, primarily because of rotation of the beam, axle and tire assembly when the brakes are locked. As the suspension travels vertically with the brakes locked it rotates the tires causing the tires to move the vehicle horizontally. If the trailer is positioned adjacent a dock, it causes the trailer to move toward or away from the dock as a result of the movement or rotation about the single pivot point. 
         [0010]    Similarly, trailing arm suspensions do not utilize the air springs full capacity as the air spring plates are not parallel in extreme operating positions, again as a result of the trailing arm pivoting about a single pivot point. 
         [0011]    Parallelogram suspensions were developed to solve a number of the problems associated with trailing arm type suspensions. However, parallelogram suspensions create problems not present in trailing arm type suspensions. Specifically, parallelogram suspensions are not inherently roll rigid or provide lateral stiffness. Parallelogram suspensions have been found to be a significant advancement over the prior art as they provide a relatively stable, safe, and comfortable ride for all types of loads. Some of these parallelogram suspensions are included in U.S. Pat. Nos. 4,114,923, 4,132,432 and 4,309,045. 
         [0012]    Advantages of the parallelogram type air spring suspensions include that the air suspended axle in a parallelogram suspension moves a very short linear distance between the loaded and unloaded positions and has no rotational component to the motion. This reduces the problem of dock walk inherent in trailing arm type suspensions. 
         [0013]    Further, the parallelogram stabilized suspension permits the air spring&#39;s full-load capacity to be utilized. The top and bottom air spring plates remain substantially parallel throughout the full range of air spring travel whether the vehicle is fully loaded or unloaded. Specifically, when the air spring is mounted on the parallel moving link of the parallelogram it allows the utilization of the air springs full travel and full load capacity. In comparison, in the typical trailing arm design where the air spring travels in an arc and “fans” open stretching the rearmost fibers of the spring while not utilizing even the full travel of the forward part of the air spring. 
         [0014]    Parallelogram type suspensions are also typically not brake reactive. That is, they do not dive or raise when brake torque is applied to the suspension system. 
         [0015]    The parallelogram suspension inherently provides the above advantages, and also locates the axle relative to the longitudinal axis of the vehicle by controlling the forward and rearward motion of the axle relative to the frame. Moreover, a parallelogram suspension also controls the path which the air spring follows as it operates to take up irregularities in the road surface. 
         [0016]    Therefore, a need exists for an air spring suspension which incorporates the benefits of a parallelogram suspension, an independent wheel suspension, and an air ride suspension. 
       SUMMARY OF THE INVENTION 
       [0017]    The present invention broadly comprises a suspension system including a base, a first parallelogram suspension having a first axis, a second parallelogram having a second axis whereby the first axis and the second axis are coaxial, and whereby movement of the first parallelogram suspension does not translate force to the second parallelogram suspension. The first and second parallelogram suspensions maybe mounted to the base and each parallelogram includes a lower connecting arm, in which each lower connecting arm is formed as a box beam. 
         [0018]    The present invention also broadly comprises a suspension system including a first side opposite a second side, a first suspension having a complete parallelogram suspension proximate the first side, and a second suspension having a complete parallelogram suspension proximate the second side. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The preferred embodiment of the invention, illustrative of the best modes in which Applicant has contemplated applying the principles of the invention, is set forth in the following description and is shown in the drawings. 
           [0020]      FIG. 1  is a side view of a truck towing a trailer having a preferred embodiment suspension system; 
           [0021]      FIG. 2  is a front view of the preferred embodiment suspension system with a trailer body attached to the frame taken generally along line  2 - 2  of  FIG. 1 ; 
           [0022]      FIG. 3  is a perspective view of the driver side of a preferred embodiment suspension system; 
           [0023]      FIG. 4  is a side view of the driver side of a preferred embodiment suspension system with the trailer wheel removed; 
           [0024]      FIG. 5  is a top view of the driver side of a preferred embodiment suspension system; 
           [0025]      FIG. 6  is a bottom view of the driver side of a preferred embodiment lo suspension system; 
           [0026]      FIG. 7  is a partial cross-sectional view of the driver side of a preferred embodiment suspension system taken generally along line  7 - 7  of  FIG. 5 ; 
           [0027]      FIG. 8  is a side partial cross-sectional view of the driver side of a preferred embodiment suspension system taken generally along line  8 - 8  of  FIG. 6 ; 
           [0028]      FIG. 9  is a partial side cross-sectional view of the driver side of a preferred embodiment suspension system in the design position viewed from a point between the driver and passenger sides; 
           [0029]      FIG. 10  is a partial side cross-sectional view of the driver side of a preferred embodiment suspension system in the jounce position viewed from a point between the driver and passenger sides; and, 
           [0030]      FIG. 11  is a partial side cross-sectional view of the driver side of a preferred embodiment suspension system in the rebound position viewed from a point between the driver and passenger sides. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0031]    At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical, or functionally similar, structural elements of the invention. While the present invention is described with respect to what is presently considered to be the preferred embodiments, it is to be understood that the invention as claimed is not limited to the disclosed aspects. 
         [0032]    Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs. Although any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of the invention, the preferred methods, devices, and materials are now described. 
         [0033]    The improved vehicle suspension of the present invention is indicated generally at suspension system  12  and rear suspension system  13 , as is particularly shown in  FIGS. 1 through 11 . Inasmuch as both suspension system  12  and rear suspension system  13  are identical being merely located on parallel but offset axes, only suspension system  12  will be described in detail. Averting to  FIG. 1 , suspension system  12  is shown secured to a trailer body  14  and being pulled by a truck  16 .  FIG. 2  shows suspension system  12  with a driver side suspension system  18  and a passenger side suspension system  20 . Trailer body  14  includes side walls  22  extending upwards and away from suspension system  12 , as well as a frame  24  interposing suspension system  12  and body  14 . Accordingly, the suspension must be sufficient to support the weight of the frame and the trailer body, as well as absorb shock due to variations in the roadway. 
         [0034]    Suspension system  12  includes a cross tube, or bending beam,  26  generally forming the front of suspension system  12  and between driver side suspension system  18  and passenger side system  20 . Cross tube  26  is preferably a rectangular tube, but may also be any suitable shape including but not limited to square, cylindrical, triangular, or any parallelepipeds. Inasmuch as both driver side suspension system  18  and passenger side suspension system  20  are identical, except that the passenger side suspension system is opposite of the driver side suspension system, only driver side suspension system  18  will be described in detail. Further, cross tube  26  may extend only partially across the vehicle or the driver side suspension system and the passenger side suspension system could each have their own cross tube without departing from the spirit and scope of the present invention. 
         [0035]    Averting to  FIG. 3 , which is a perspective view of the driver side suspension system, a mounting support, or base,  28  generally forms the upper portion of the suspension system while a control arm  30  forms the lower and outer portion of the suspension system. Although mounting support  28  forms the upper portion of the suspension system, it is within the spirit and scope of the invention as claimed for the frame or any other suitable stationary member to form the upper portion of the suspension system. 
         [0036]    Control arm  30  is preferably arc-like in shape to provide two perpendicular surfaces for forming a lower suspension portion and a mounting location for a tire-wheel assembly  62 , although the control arm may be any size or shape suitable for interaction with the suspension system, including a solid bar. Control arm  30  also includes an outer support cover  25  and an inner support cover  27  arranged to provide additional structural integrity to the control arm. Mounting support  28  includes a top surface abutting frame  24 , a bottom surface arranged to receive a spring, and two sidewalls  29  (not shown in  FIGS. 3) and 31  extending perpendicularly downward from the top surface to generally form a hanger bracket. Mounting support  28  has a pair of complimentary shaped openings  23  which are parallel to and share a common axis with one another, but may also have only one opening instead of two. Openings  23  receive and are adjacent to the outer walls of cross tube  26 . Further, a spindle  32  extends outward from the outer portion of control arm  30  and is arranged to receive a wheel and brake assembly (not shown). 
         [0037]    In accordance with one of the main features of the present invention, an upper connecting arm  34  includes a first end  36  secured to cross tube  26  at a pivot joint  37 . The pivot joint connects a pivot bracket  38  and mounting support  28  via a through hole in the side wall of mounting support  28 . The upper connecting arm also includes a second end  40  secured to control arm  30  through a pivot joint  39  at mounting tabs  42  integral to and extending away from control arm  30 . First and second ends  36  and  40  are preferably arcuate in shape and the central body of upper connecting arm  34  is preferably rectangular, although any suitable shape may be utilized. Pivot joints  37  and  39  include flexible rubber or urethane bushings, or a similarly situated material, to provide rotational control. Upper connecting arm  34  includes a through hole in both first end  36  and second end  40  arranged to accept a bolt. 
         [0038]    In accordance with another of the main features of the invention,  FIG. 4  shows a lower connecting arm  44  having a first end  46  secured to mounting support  28  via a through hole in sidewall  29  of mounting support  28 . Control arm  30  includes brackets  51  and  57  ( FIG. 7 ) to connect a second end  48  of the lower connecting arm at pivot joints  50  and  54 . First and second ends  46  and  48  are preferably arcuate in shape and the central body of lower connecting arm  44  is preferably rectangular. As discussed below in greater detail, the first and second ends of the lower connecting arm are secured to mounting support  28  and control arm  30  with a nut and bolt assembly  52  extending through first end  46  and through second end  48 , respectively, in a split tube attachment method. The split tube attachment method incorporates a pair of split tubes with a hole in which a bolt passes. The camber and toe are then adjusted to meet specifications and the split tube is then welded to prevent movement of the split tube assembly. 
         [0039]    Similar to upper connecting arm  34 , lower connecting arm  44  also includes a through hole in each of first end  46  and second end  48  which may, in contrast to the upper connecting arm, include roller bearings instead of bushings. Due to the increased width of the lower connecting arm, each through hole may have a pressed roller bearing in each end. Further, roller bearings are preferably located at all connection points between lower connecting arm  44  and mounting support  28 . Similar to pivot joints  39 , the connections between lower connecting arm  44  and control arm  30  may include roller bearings to allow controlled rotational movement of the suspension and full vertical movement of the control arm. 
         [0040]    Averting now to  FIGS. 5 and 6 , first end  46  of lower connecting arm  44  is secured to mounting support  28  in two places, at outer side wall  29  and inner side wall  31  of mounting support  28 . Further, the lower connecting arm is approximately the same width as the distance between the sidewalls of mounting support  28  with the addition of a thrust washer of approximately 0.125 inches thick. Lower connecting arm  44  is secured to the mounting support at pivot joints  53  and  55 . Second end  48  of lower connecting arm  44  is secured to control arm  30  through outer pivot joint  50  on bracket  51  and inner pivot joint  54  on bracket  57  with nuts and bolts or any other suitable connecter. Similar to the first side, second end  48  is approximately the same width as the distance between pivot brackets  51  and  57 . 
         [0041]    Accordingly, a full parallelogram suspension is formed at driver side suspension system  18  with mounting support  28  forming the base of the parallelogram, while control arm  30  forms the opposing side of the parallelogram. Upper connecting arm  34  and lower connecting arm  44  form the two remaining parallel sides which are adjacent to the mounting support and control arm. Thus, each side of suspension system  12  incorporates a full parallelogram suspension at each wheel which is independent of the parallelogram suspension at the opposing wheel. 
         [0042]    In accordance with another of the main features of the invention,  FIGS. 7 and 8  are partial cross-sectional views of driver side suspension system  18  showing an air spring  56 . Air spring  56  is intermediate mounting support  28  and control arm  30 . In particular, both mounting support  28  and control arm  30  have openings to allow bolts  58  to secure the air spring between the mounting support and the control arm. Air spring  56  also includes an air line inlet  60 , as seen in  FIGS. 3 and 5 , to regulate the air springs dampening characteristics through an air compressor. 
         [0043]    As set forth hereinabove, suspension system  12  has been described in detail. As should be apparent to one of ordinary skill in the art, suspension system  12  may be utilized when only a single axle suspension system is required. However, if tandem axle arrangements are required, for example those arrangements utilized on known trailer vehicles, suspension system  12  is utilized in combination with rear suspension system  13  as shown specifically in  FIG. 1 . Rear suspension system  13  is arranged in the same manner and orientation as suspension system  12 . 
         [0044]    In a preferred embodiment, when trailer body  14  traverses an irregularity in the road, the force from the irregularity will cause tire-wheel assembly  62  to raise toward trailer body  14 . As tire-wheel assembly  62  raises, the parallelogram suspension at that tire-wheel assembly will pivot upwardly. Taking driver side suspension system  18  for example in  FIG. 4 , vertical movement of spindle  32  in the direction indicated by arrow A translates into rotational movement at the pivot joints and particularly upper connecting arm  34  and lower connecting arm  44  in the direction indicated by arrow B. 
         [0045]    Rotational movement also creates an axial movement in control arm  30  generally along the compression axis of air spring  56  in the direction indicated by arrow A ( FIG. 4 ). The rotational movement of the suspension system is resisted by air spring  56  which acts to dampen the resulting vertical movement of control arm  30 . Since the rotational movement of the parallelogram suspension is confined to each individual tire-wheel assembly  62 , passenger side suspension system  20  is not affected and is capable of full independent travel. 
         [0046]    Referring to  FIG. 9 , driver side suspension system  18  of the present invention is shown with air spring  56  in the design position, which may occur when the air springs are inflated for travel and trailer body  14  is loaded with cargo. The distance between spindle  32  and the ground is represented by distance SLR and is preferably 14.3 inches in the design position, jounce (see infra), and rebound (see infra) when a 17.5 inch tire is used, although a 22.5 inches tire or any other size tire is within the spirit and scope of the present invention as claimed. Outer cover support  25  is approximately 5.1 inches from the ground, while distance DP represents the distance between the ground and mounting support  28 , which is approximately 13.5 inches in the preferred embodiment. 
         [0047]      FIG. 10  is driver side suspension system  18  shown in the jounce, or compressed, position when the air is exhausted from air spring  56 . As previously noted, the distance between spindle  32  and the ground is still approximately 14.3 inches in the jounce position. In this position, the distance between outer cover support  25  and the ground is approximately 5.1 inches, while distance JP is approximately 11 inches. 
         [0048]      FIG. 11  is driver side suspension system  18  shown in the rebound position with the suspension fully extended in the vertical direction. The distance between spindle  32  and the ground again remains approximately 14.3 inches in the rebound position. In this position, the distance between outer cover support  25  and the ground is approximately 5.1 inches, while distance RP is approximately 15.9 inches. Further, in a preferred embodiment, the spindle has a vertical travel of approximately 4.9 inches and a horizontal travel of approximately 1.1 inches. 
         [0049]    As can be seen in  FIGS. 9 through 11 , control arm  30  shares a common axis with air spring  56 . In particular, since air spring  56  is secured directly between control arm  30  and mounting support  28 , the air spring and control arm share the same horizontal axis. Advantageously, this arrangement allows full use of air spring  56  without any fanning of the air spring due to the minimal amount of off-center loading. In particular, since the control arm and air spring share a common axis, all movement of control arm  30  is equally imposed on air spring  56 . Accordingly, the spring rate of air spring  56  can be reduced to approximately one-fourth of a traditional parallelogram suspension spring rate and provide a remarkably better ride quality. 
         [0050]    In summary, suspension system  12  provides a parallelogram suspension with all the advantages known in the art, while still providing an independent wheel action. Driver side suspension system  18  operates such that as tire-wheel assembly  62  moves, control arm  30  moves vertically and upper connecting arm  34  and lower connecting arm  44  pivot in unison to maintain a constant angle throughout the path of travel. Similarly, inasmuch as suspension system  18  incorporates a full parallelogram suspension at each tire-wheel assembly  62 , forces encountered at driver side suspension system  18  are absorbed by air spring  56  and are not transferred to the tire-wheel assembly at passenger side suspension system  20 . Thus, suspension system  12  enhances the ride quality and damping characteristics of the suspension system by isolating each parallelogram suspension from one another. 
         [0051]    Accordingly, the suspension system is an effective, safe, inexpensive, and efficient device that achieves all the objectives of the invention, provides for eliminating difficulties encountered with prior art devices, and systems, and solves problems and obtains new results in the art. 
         [0052]    In the foregoing description, certain terms have been used for brevity, clearness, and understanding; but no unnecessary limitations are to be implied therefrom beyond the requirement of the prior art, because such terms are used for descriptive purposes and are intended to be broadly construed. 
         [0053]    Moreover, the description and illustration of the invention is by way of example, and the scope of the invention is not limited to the exact details shown or described. 
         [0054]    Having now described the features, discoveries, and principles of the invention, the manner in which the suspension system is constructed and used, the characteristics of the construction, and the advantageous new and useful results obtained; the new and useful structures, devices, elements, arrangement, parts, combinations, and methods are set forth in the appended claims.