Abstract:
Axle seats are disclosed for incorporation into vehicle suspensions of the type having a laterally extending axle and a longitudinally extending leaf spring. The axle seat includes a seat portion, a clamp group mounting surface, and an air spring mounting flange. A sidewall of the axle seat connects the seat portion to the clamp group mounting surface and the air spring mounting flange. The clamp group mounting surface and air spring mounting flange are configured to be positioned at different heights when the seat portion is connected to an axle. A second sidewall and air spring mounting flange may be provided, in which case the air spring mounting flanges may be spaced apart to provide an area through which a leaf spring may extend.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of U.S. patent application Ser. No. 11/919,534, filed Nov. 2, 2009 now U.S. Pat. No. 8,029,008, which is a National Stage filing of PCT Patent Application No. PCT/US2006/015836, filed Apr. 26, 2006, which is a continuation of U.S. patent application Ser. No. 11/115,949, filed Apr. 27, 2005 now abandoned, all of which are hereby incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to vehicle suspensions and components thereof. More particularly, the present invention relates to leaf spring suspensions. 
     Leaf springs are commonly used as active components in vehicle suspensions. Examples of suspensions using a leaf spring are shown and described in U.S. Pat. No. 5,938,221 (Wilson), the disclosure of which is hereby incorporated herein by reference. 
     One of the shortcomings associated with the design of leaf spring suspensions is due to the fact that in order to lower the vertical spring rate to a desirable level, the leaf spring sometimes must be increased in length beyond the packaging constraints of the vehicle. In particular, in certain vehicles, there are limitations on the space available to accommodate the longer length spring required to achieve a lower spring rate for a given suspension. 
     Another shortcoming associated with the design of leaf spring suspensions is that the axle travel is conventionally limited by the maximum allowable leaf spring deflection, which is limited by the peak stress of the leaf spring and in turn is a characteristic based on the material of construction for the leaf spring. In some cases, leaf spring suspensions having a desired spring rate cannot be used because the stress imparted upon the leaf spring is too great and/or the maximum allowable leaf spring deflection would not support the load required within the maximum axle travel limits. 
     Another shortcoming associated with leaf spring suspensions that use air springs is that if the one or more air springs are not balanced about the vehicle axle centerline, excessive deflection and/or high stress gradients could be exerted on the leaf spring during vertical loading and would also add to spring windup during acceleration and braking. For front air suspensions using a single air spring, the maximum vehicle load would necessitate use of a large diameter air spring, which could be difficult to package in the available space. 
     Another shortcoming associated with leaf spring suspensions is that conventionally the attachment of the leaf spring to the vehicle axle has been carried out in a way that produces a mechanical metal-to-metal connection between the leaf spring and the axle. This conventional means of connecting the leaf spring to the vehicle axle negates utilization of a section of the leaf spring, namely its spring seat section, as part of the active component, giving the leaf spring a shorter effective length than its true physical length and increasing the overall spring rate of the leaf spring. In addition, this metal-to-metal connection can be a limitation of the fatigue life for the leaf spring. 
     Another shortcoming associated with leaf spring suspensions is that fabricated axle seats have not been applied to front fabricated steer axles. The vehicle components conventionally used have been more costly in terms of manufacturing and material costs. In addition, the conventional vehicle components have been heavier, which in the case of commercial vehicles, translates into reduced payload capacity. 
     Accordingly, it is desirable to overcome one or more of the foregoing shortcomings, or alternatively other shortcomings not specified herein but associated with prior leaf spring suspensions. 
     The benefits of the preferred forms of the novel subject matter set forth herein will become apparent from the following description. It will be understood, however, that an apparatus could still appropriate the invention claimed herein without accomplishing each and every one of those benefits gleaned from the following description. The appended claims, not the benefits of the novel subject matter set forth herein, define the subject matter protected by law. Any and all benefits are derived from the preferred forms of the invention, not necessarily the invention in general. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       In the following detailed description, reference will frequently be made to the following views of the drawing, in which like reference numerals refer to like components, and in which: 
         FIG. 1  is a perspective view of a vehicle axle and vehicle suspension components constructed in accordance with the principles and teachings set forth herein; 
         FIG. 2  is a side view of the vehicle axle and vehicle suspension components illustrated in  FIG. 1 ; 
         FIG. 3  is a rear view of the vehicle axle and vehicle suspension components illustrated in  FIGS. 1-2 ; 
         FIG. 4  is a front view of the vehicle axle and vehicle suspension components illustrated in  FIGS. 1-3 ; 
         FIG. 5  is a perspective view of the vehicle axle and axle clamp assembly components illustrated in  FIGS. 1-4 , showing a leaf spring extending transversely to the vehicle axle; 
         FIG. 6  is a perspective view of the vehicle axle and certain of the axle clamp assembly components illustrated in  FIGS. 1-5 ; 
         FIG. 7  is a perspective view illustrating another embodiment of the axle clamp assembly components; 
         FIG. 8  is a perspective view illustrating certain of the axle clamp assembly components illustrated in  FIG. 7 ; 
         FIG. 9  is a perspective view of a vehicle axle and vehicle suspension components constructed in accordance with the principles and teachings set forth herein; 
         FIG. 10  is a front view of the vehicle axle and vehicle suspension components illustrated in  FIG. 9 ; 
         FIG. 11  is a side view of the vehicle axle and vehicle suspension components illustrated in  FIGS. 9-10 ; 
         FIG. 12  is a perspective view of a vehicle axle and another embodiment of axle clamp assembly components; 
         FIG. 13  is a sectional view of  FIG. 12 , taken along lines  13 - 13  thereof; 
         FIG. 14  is a perspective view of another embodiment of axle clamp assembly components; 
         FIG. 15  is a sectional view of  FIG. 14 , taken along lines  15 - 15  thereof; 
         FIG. 16  is a perspective view of another embodiment of axle clamp assembly components; 
         FIG. 17  is a sectional view of  FIG. 16 , taken along lines  17 - 17  thereof; 
         FIG. 18  is a perspective view of a vehicle axle and certain vehicle suspension components; 
         FIG. 19  is a front view of the vehicle axle and vehicle suspension components illustrated in  FIG. 18 ; 
         FIG. 20  is a side view of the vehicle axle and vehicle suspension components illustrated in  FIGS. 18-19 ; 
         FIG. 21  is a perspective view of another embodiment of axle clamp assembly components; and 
         FIG. 22  is a sectional view of  FIG. 21 , taken along lines  22 - 22  thereof. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1-4  illustrate some of the vehicle components present on one side of a vehicle. Illustrated in  FIGS. 1-4  are a vehicle axle  30  and its associated vehicle suspension. Vehicle axle  30  is shown in the form of a front fabricated vehicle steering axle. The details of the structure of the illustrated vehicle axle  30  are set forth in U.S. Pat. No. 6,609,764 (Dudding et al.), the disclosure of which is hereby incorporated herein by reference. Vehicle axle  30  extends laterally across the vehicle. It will be understood that the opposite side of the vehicle includes the opposite side of vehicle axle  30  and duplicate suspension components. 
     The vehicle suspension illustrated in  FIGS. 1-4  includes a steering knuckle  32  having a spindle  34  mounted on the end of vehicle axle  30  in known manner by a king pin (not shown). Steering knuckle  32  and spindle  34  preferably embody one of the forms disclosed in U.S. Pat. No. 6,616,156 (Dudding et al.), the disclosure of which is also hereby incorporated herein by reference. A vehicle wheel (not shown) is mounted on spindle  34  in known manner. 
     A tie rod  36  is connected to a tie rod arm  32   a  of the steering knuckle and extends laterally across the vehicle centerline from one side of the vehicle to the other side. The opposite end of tie rod  36  is connected to the tie rod arm of the steering knuckle positioned on the opposite side of the vehicle. With this arrangement, tie rod  36  can be used to control steering of the vehicle. 
     The vehicle suspension also includes a shock absorber  38  connected between axle seat  44  and a vehicle frame rail (not shown). The referenced vehicle frame rail is preferably a longitudinally extending member having the standard C-shaped cross-section well known in the art and as shown in the incorporated U.S. Pat. No. 5,938,221. A first shock absorber mounting unit  40  including ears  40   a  and  40   b  is welded or otherwise attached to axle seat  44 . A second shock absorber mounting unit  42  is bolted or otherwise attached to the vehicle frame. The second shock absorber mounting unit  42  is illustrated in the form of a mounting bracket but may take other forms. Shock absorber  38  can be connected between first shock absorber mounting unit  40  and second shock absorber mounting unit  42  in the illustrated manner. 
     The vehicle suspension also includes an axle seat  44  press-fit to vehicle axle  30  in a manner such that the axle seat sits atop the vehicle axle. Axle seat  44  is preferably constructed as a fabricated assembly, but those skilled in the art will appreciate that this axle seat could also be made as a casting. The axle seat  44  illustrated in  FIGS. 1-4  is better illustrated in  FIGS. 5 and 6 . Accordingly, the details of axle seat  44  shall be described herein with reference to  FIGS. 5 and 6 . 
     The vehicle suspension also includes a leaf spring shown in the form of a dual-leaf leaf spring  46  extending longitudinally and connected to the vehicle frame at separated points thereof by frame hanger brackets, shackles or similar vehicle suspension components (not shown), as is well known in the art and as is illustrated in the incorporated U.S. Pat. No. 5,938,221. The dual-leaf leaf spring  46  includes a full leaf  46   a  having eyes  48 ,  50  on opposite ends thereof to allow the dual-leaf leaf spring to be connected to the vehicle frame rail at its opposite ends. The dual-leaf leaf spring  46  also includes a half leaf  46   b  having a military wrap  52  positioned on one end thereof. The other end of the half leaf  46   b  and a mid-portion of full leaf  46   a  are clamped to axle seat  44  through use of inverted U-bolts  54   a ,  54   b  (see also  FIG. 5 ). The full leaf  46   a  and half leaf  46   b  are also secured together by a spring clip  47  and by the military wrap  52  inasmuch as it extends around the outside of the outside diameter of leaf spring eye  48 . 
     Leaf spring  46  can be considered to have five general sections. The first section of leaf spring  46  is front spring eye  48 . The second section of leaf spring  46  is the front limb, which extends generally from the front spring eye  48  of the leaf spring to the front portion of the clamp group section of the suspension. The third section of leaf spring  46  is the spring seat section, which corresponds to that section of the leaf spring that extends along the clamp group section of the suspension. The fourth section of leaf spring  46  is the rear limb, which extends generally from the rear portion of the clamp group section of the suspension to the rear spring eye  50  of the leaf spring. The fifth section of leaf spring  46  is its rear spring eye  50 . The rear limb of leaf spring  46  is longer and thinner than the front limb of the leaf spring. With this construction, the rear limb of leaf spring  46  contributes less to the roll stiffness than the front limb of the leaf spring. The rear limb of leaf spring  46  adds to suspension articulation. 
     The vehicle suspension also includes a front air spring  62  seated on and secured to an axle clamp top pad  64  (see also  FIG. 5 ) and also secured to an air spring mounting bracket  66 . Air spring mounting bracket  66  is mounted to the longitudinally extending vehicle frame rail. 
     The vehicle suspension also includes a rear air spring  68  seated on and secured to axle seat  44  (see also  FIG. 5 ) and also secured to an air spring mounting bracket (not shown), which in turn is mounted to the vehicle frame rail. 
     As illustrated in  FIGS. 1-4 , front air spring  62  has a diameter smaller than the diameter of rear air spring  68 . Front air spring  62  is positioned in front of the vehicle axle centerline, and rear air spring  68  is positioned behind the vehicle axle centerline. 
     Referring to  FIGS. 5-6 , the axle seat  44  illustrated in  FIGS. 1-4  is illustrated therein.  FIGS. 5-6 , however, illustrate a mono-leaf leaf spring  70 , which preferably is constructed in accordance with the teachings of U.S. Pat. No. 5,938,221. It will be appreciated that the full leaf  46   a  of the dual-leaf leaf spring  46  illustrated in  FIGS. 1-4  also preferably has such construction. 
     As shown in  FIGS. 5-6 , the axle seat  44  includes a C-shaped seat portion  72  that extends over most of the front and rear sides of the axle body and over the top side of the axle body. With this construction, seat portion  72  of axle seat  44  has an open end. The axle seat portion  72  is press-fit onto the vehicle axle  30 . The front and rear sides of the seat portion  72  of axle seat  44  include racetrack shaped cutouts  74  that permit axle seat  44  to be welded to vehicle axle  30  (see also  FIG. 4 ). In particular, weld lines are formed about the perimeter of the racetrack shaped cutouts  74  on the front and rear sides of the axle body. The vertical and longitudinal loads are carried by the mechanical press-fit connection of axle seat portion  72  to vehicle axle  30 , while the braking, acceleration and lateral loads are carried by the weld formed about the perimeter of racetrack  74 . 
     Axle seat  44  also includes inboard and outboard sidewalls  76 ,  78  extending from the C-shaped seat portion  72 . Positioned on top of sidewalls  76 ,  78  at the front portion of the sidewalls is a clamp group mounting surface  80 . Clamp group mounting surface  80  is positioned forward of vehicle axle  30  and includes bores  82  sized to receive the legs of the inverted U-bolts. The legs of the inverted U-bolts preferably have threaded ends and are fastened to the underside of axle seat  44  by appropriate fastener nuts or similar fastening components. 
     Axle seat  44  also includes air spring mounting flanges  84  extending laterally from the inboard and outboard axle seat sidewalls  76 ,  78 . The air spring mounting flanges  84  have bores  86  extending through them to enable the rear air spring to be secured to the axle seat. The air spring mounting flanges  84  are spaced apart to provide an area through which leaf spring  70  may extend. 
     In that regard, leaf spring  70  extends longitudinally, as described above, such that the spring seat area thereof extends over clamp group mounting surface  80 . Axle clamp top pad  64  is positioned on top of the spring seat area of leaf spring  70  and inverted U-bolts  54   a ,  54   b  are used to clamp the leaf spring to axle seat  44  between axle clamp top pad  64  and the clamp group mounting surface  80  of the axle seat. The clamp group mounting surface  80  is positioned ahead of the vehicle axle such that the spring seat area of leaf spring  70  (i.e., that portion of the leaf spring clamped to the clamp group mounting surface) is not positioned symmetrically about the vehicle axle. A metal-to-metal mechanical connection between the leaf spring  70  and the axle seat  44  is achieved. Axle clamp top pad  64  includes grooved portions to accommodate the inverted U-bolts  54   a ,  54   b . Axle clamp top pad  64  also includes a bore  87  to permit the front air spring to be secured thereto. 
       FIGS. 7-8  illustrate an axle seat  144  having a construction similar to the axle seat  44  illustrated in  FIGS. 1-6 . Axle seat  144 , however, is secured to the axle body of vehicle axle  30  by fasteners  88  shown in the form of bolts, which extend through bores formed within the C-shaped seat portion of axle seat  144 . Further details regarding this use of fasteners in lieu of the described welding will be described hereinafter with reference to other figures in the drawing of this application. 
       FIGS. 9-11  illustrate a fabricated axle seat  244 . Fabricated axle seat  244  includes a C-shaped axle seat portion  272  that extends over most of the front and rear sides of the axle body and over the top side of the axle body, leaving an open end over the box-shaped axle body. The axle seat portion  272  is press-fit to the vehicle axle body. The front and rear sides of the seat portion  272  of axle seat  244  include racetrack shaped cutouts  274  that permit axle seat  244  to be welded to vehicle axle  30 . In particular, weld lines are formed about the perimeter of the racetrack shaped cutouts  274  on the front and rear sides of the axle body. 
     Axle seat  244  also includes inboard and outboard sidewalls  276 ,  278  extending from the C-shaped seat portion  272 . Positioned on top of sidewalls  276 ,  278  is a clamp group mounting surface  280 . Clamp group mounting surface  280  is positioned directly above vehicle axle  30 , as best shown in  FIG. 11 , and includes bores sized to receive fasteners. 
     Leaf spring  270  extends longitudinally, as described above, such that the spring seat area thereof extends over the clamp group mounting surface  280 . An axle clamp top pad  264  is positioned on top of the spring seat area of leaf spring  270  and bolts  254  are used to clamp leaf spring  270  between top pad  264  and axle seat  244  symmetrically about the centerline of the vehicle axle, as best shown in  FIG. 11 . A metal-to-metal mechanical connection between the leaf spring  270  and the axle seat  244  is achieved. 
     The vehicle suspension includes an air spring  265  seated on and secured to axle clamp top pad  264 . Air spring  265  is also secured to a vehicle frame rail (not shown) in known manner. The vehicle suspension also includes a leaf spring end attachment part  267 , which preferably is constructed in accordance with the teachings and principles of the invention disclosed in U.S. Pat. No. 6,485,040 (Dudding), the disclosure of which is also hereby incorporated herein by reference. As shown, leaf spring  270  does not have a rear leaf spring eye. Accordingly, the fifth general section of leaf spring  270  is not a rear spring eye, but rather the rear attachment part section. 
       FIGS. 12-13  illustrate a fabricated axle seat  344  having a construction similar to the fabricated axle seat  244  illustrated in  FIGS. 9-11 . Fabricated axle seat  344 , however, is secured to the axle body of vehicle axle  30  by fasteners  388  shown in the form of bolts, which extend through bores formed within the seat portion of the axle seat. With this axle seat and the others disclosed herein using fasteners, the fasteners could take a variety of forms such as rivets and Huckbolt® two-part fasteners having a pin and collar construction. In addition, as shown in  FIG. 13 , reinforcement components  389  shown in the form of tubes or channels are attached to the inside walls of the axle body to provide a more rigid structure. With this axle seat and the others disclosed herein using fasteners, the reinforcement components can be attached to the axle body by, for example, mechanical means (such as, for example, putting a coined recess in the axle body inner wall to receive a tube or channel reinforcement component and secure the reinforcement component by an interference fit). The reinforcement component may also be attached by adhesive or by welding (as shown). It will be appreciated that similar reinforcement components are also used with the other axle seats disclosed herein and using fasteners to attach to the axle. 
     Similar to  FIGS. 1-6 ,  FIGS. 14 and 15  illustrate axle seat  44  press-fit and welded to the axle body of vehicle axle  30 . In  FIGS. 14 and 15 , however, the spring seat section of leaf spring  70 , namely that section of leaf spring  70  within the clamp group section of the suspension, is surrounded by a high durometer rubber material  92  or other suitable elastomer. A top plate  94  is fastened to the clamp group mounting surface  80  by fasteners extending through bores  82  (see also  FIG. 6 ). The top plate  94  is sized and constructed to compress the rubber material  92  around the spring seat section of leaf spring  70  such that the forces due to such compression contain the leaf spring longitudinally and laterally. With this clamping technique, there is no hard mechanical (i.e. metal to metal) connection. 
     Similar to  FIGS. 7 and 8 ,  FIGS. 16 and 17  illustrate the axle seat  144  press-fitted and fastened to the axle body of vehicle axle  30  with the fasteners preferably extending through reinforcement components secured to the inner walls of the axle body.  FIGS. 16 and 17  illustrate use of the clamping technique illustrated above, namely the spring seat section of the leaf spring is encapsulated by a high durometor rubber material  92  and a top plate  94  is secured to the clamp group mounting surface of the axle seat. The top plate  94  compresses the rubber material  92 , as described above with reference to  FIGS. 14 and 15 . 
     Similar to  FIGS. 9-11 ,  FIGS. 18-20  illustrate axle seat  244  press-fit and welded to the axle body of vehicle axle  30 .  FIGS. 18-20  illustrate use of the clamping technique shown in  FIGS. 14-17  and described above. Similarly,  FIGS. 21 and 22  illustrate the axle seat  344  press-fit and fastened to the axle body of vehicle axle  30 , as shown in  FIGS. 12 and 13 ; however,  FIGS. 21 and 22  illustrate use of the clamping technique shown in  FIGS. 14-20  and described above with reference to  FIGS. 14-17 . 
     As described above, axle seat  44  illustrated in  FIGS. 1-6 ,  14 - 15  and axle seat  144  illustrated in  FIGS. 7-8 ,  16 - 17  have their clamp group mounting surfaces positioned forward of the vehicle axle such that the clamp group is not positioned symmetrically about the centerline of the vehicle axle. By moving the clamp group ahead of the axle, a longer rear limb length for the leaf spring used in the suspension is achieved. This yields a softer, more compliant rear limb. Conversely, a shorter front limb length for the leaf spring is achieved, yielding a stiffer front limb suitable to handle roll stiffness, as described in pending U.S. Ser. No. 09/572,736 (Dudding), filed May 17, 2000, the disclosure of which is hereby incorporated herein by reference. The movement of the clamp group forward of the vehicle axle is especially advantageous for suspensions used in those vehicles having limited available space for installing the suspension. Such packaging constraints are common in vocational truck vehicles, for example. 
     Having the clamp group positioned ahead of the vehicle axle also allows greater travel at the spindle/vehicle axle centerline due to the lever arm or motion ratio, which is based upon the ratio of the distance between the front leaf spring eye and the centerline of the clamp group section (first lever arm) to the distance between the front leaf spring eye and the vehicle axle centerline (second lever arm). In particular, maximum allowable deflection at a vehicle axle is typically limited due to the peak stress characteristic of the leaf spring material, which in turn limits the maximum spring deflection. With the axle clamp group positioned ahead of the vehicle axle, for a given deflection of the leaf spring at the axle clamp group, the spindle can deflect a greater distance due to the motion ratio. Accordingly, leaf spring stress for a given amount of axle travel is reduced, and maximum axle travel is increased beyond the limitations existing for conventional suspension designs having the clamp group configured symmetrically about the vehicle axle centerline. 
     The configuration of the front air spring  62  and rear air spring  68  positioned ahead of and behind the vehicle axle  30 , respectively, provides additional load carrying capacity for the suspension and balances loads about the vehicle axle centerline. Accordingly, the air springs will help prevent leaf spring windup during acceleration and braking. The air springs are located to provide support for suspension load by using the advantage of the motion ratios. The air springs are sized to fit within the packaging envelope and still allow room for motion of the vehicle steering arm. The air springs allow the vehicle ride height to be level when the vehicle is fully loaded or overloaded, without inducing greater stress on the leaf spring. 
     The combination of the leaf spring and air springs support the suspension loads while allowing suspension articulation and providing primary roll stiffness. 
     With reference to  FIGS. 14-22 , in each of those figures there is shown the clamping technique where the seat area section of the leaf spring is encapsulated in rubber under compression. Because the leaf spring-to-axle connection using this clamping technique does not employ a hard mechanical metal-to-metal connection, the entire length of the leaf spring (including the seat area section thereof) can be used to support the vehicle weight. This increases the effective (utilizable) length of the leaf spring, which reduces its spring rate and improves vehicle ride. In addition, fatigue life of the leaf spring is improved. 
     While this invention has been described with reference to certain illustrative aspects, it will be understood that this description shall not be construed in a limiting sense. Rather, various changes and modifications can be made to the illustrative embodiments without departing from the true spirit and scope of the invention, as defined by the following claims. Furthermore, it will be appreciated that any such changes and modifications will be recognized by those skilled in the art as an equivalent to one or more elements of the following claims, and shall be covered by such claims to the fullest extent permitted by law.