Patent Abstract:
An insert disposed between two cooperating leaf springs. The insert includes a body including a stem having a plurality of radially extending ribs inserted into an aperture in a first leaf spring. The body includes a face which slidably engages a second leaf spring. The face includes a plurality of circular protrusions extending therefrom. A pin is inserted into a central bore formed by cooperating fingers that form the body, causing an outwardly extending radial retention force to be exerted onto the surface of the aperture in the first leaf spring.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation of U.S. patent application Ser. No. 09/617,902 filed on Jul. 17, 2000. The disclosure of the above application is incorporated herein by reference. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to leaf springs and, more particularly, to an insert adapted to be disposed between leaf springs to reduce noise.  
         BACKGROUND OF THE INVENTION  
         [0003]    In a conventional manner, leaf springs are used at each side of a vehicle to provide the suspension mechanism between the frame of the vehicle and the axle. Leaf springs are used in many applications, and more prominently in pickup trucks and other large trucks. The general configuration of a leaf spring includes an upper leaf spring pivotally fixed at one end to the frame and the other end connected via a shackle to the frame of the vehicle. An axle is mounted at an intermediate point along the length of the spring. The arrangement results in a leaf spring having a generally elliptic contour. Usually, a plurality of leaf springs are mounted in decreasing length under the upper spring. The vertical displacement of an axle allows a leaf spring to flex according to factors such as spring thickness and mounting position. As a vertical force is introduced into the leaf spring configuration, the individual springs are encouraged to slidably engage each other as the elliptical contour flattens out and the displacement force is dampened. The sliding engagement of a first leaf spring and a second leaf spring can result in unpleasant frictional noises.  
           [0004]    The frictional noise associated with a leaf spring configuration have been addressed by providing a plastic insert having a disk portion and a stem portion. The stem portion is inserted through an aperture in a first leaf spring and the disk portion is aligned for slidable engagement with an opposing, second leaf spring. This approach reduces frictional noise but also presents drawbacks. Often the paint and sediment associated with the coating on a leaf spring becomes trapped between the insert and the spring resulting in added frictional noise. Further, existing inserts do not engage the leaf spring to which they are mounted as positively as possible.  
           [0005]    Thus, it is desirable to provide a textured surface on the face of the plastic insert to facilitate removal of the paint and sediments to prevent the formation of high spots on the spring. It is also desirable to provide an increased retention force from the stem onto the inner wall forming an aperture of the leaf spring.  
         SUMMARY OF THE INVENTION  
         [0006]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.  
           [0007]    It is an object of the present invention to provide an insert adapted to be disposed between an upper and lower leaf spring that is capable of decreasing the frictional noise created from conventional leaf spring configurations.  
           [0008]    It is another object of the present invention to provide an insert having a body including an aperture, a stem having a plurality of fingers including a plurality of radially extending ribs, and a pin adapted to be inserted through a central bore formed from the fingers and causing the side portions to expand in outward directions.  
           [0009]    It is a further object of the present invention to provide an insert having a body with a face including a plurality of protruding members which slidably engage the lower surface of an adjacent leaf spring.  
           [0010]    It is yet another object of the present invention to provide an insert with a body and a stem having an inwardly extending ridge portion that cooperates to secure an outwardly extending ridge portion on the pin.  
           [0011]    It is yet another object of the present invention to provide a pin having a first end and a second end. The first end has an outer diameter that increases when traversing the pin from the first end toward the second end.  
           [0012]    It is yet another object of the present invention to provide a one-piece molded component having a body including a stem with a pin interconnected thereto.  
           [0013]    It is yet another object of the present invention is to provide a leaf spring insert which is simple in structure, inexpensive to manufacture, and durable in use.  
           [0014]    The present invention is directed to an apparatus for reducing frictional noise between leaf springs. The apparatus includes a body having an aperture and a stem having a central bore defined by a plurality of fingers. The plurality of fingers has first and second ends, where the first ends of the plurality of fingers are coupled to a surface of the body around the perimeter of the aperture and projecting away from the surface body. A plurality of retainers are formed on an outer surface of at least one of the plurality of fingers. An insert portion is inserted through the central bore of the stem, thereby expanding the fingers in outward directions.  
           [0015]    This invention is also directed to a leaf spring assembly including a first leaf spring and a second leaf spring having an aperture. An insert is disposed between the first and second leaf springs. The insert includes a body portion and a stem portion. The stem portion has a plurality of fingers adapted to be inserted through the aperture of the second leaf spring. A pin is adapted inserted through a central bore formed by the plurality of fingers, thereby displacing said first and second fingers outwardly to engage said aperture.  
           [0016]    This invention is also directed to a method of reducing frictional noise associated with a first leaf spring and an adjacent second leaf spring. The method includes the step of molding a one piece component including a base, a stem portion having a central bore, and a pin interconnected to the stem portion. The method also includes the steps of inserting the stem portion through an aperture in a first leaf spring and removing the pin from the stem portion and displacing the pin into the central bore.  
           [0017]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood however that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.  
           [0018]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0020]    [0020]FIG. 1 is an exploded, side view of a conventional leaf spring configured with the leaf spring inserts of the present invention;  
         [0021]    [0021]FIG. 2 is a perspective view of the leaf spring insert as a single piece prior to separation of the pin insert from the stem portion;  
         [0022]    [0022]FIG. 3 is a cutaway view of the leaf spring insert shown disposed through an aperture in a leaf spring;  
         [0023]    [0023]FIG. 4 is a cutaway view of the leaf spring insert shown prior to insertion of the pin;  
         [0024]    [0024]FIG. 5 is a perspective view of the leaf spring insert installed in a leaf spring;  
         [0025]    [0025]FIG. 6 is a cutaway view of an installed leaf spring insert shown to illustrate the circular extensions of the upper face;  
         [0026]    [0026]FIG. 7 is a perspective view of the leaf spring insert to illustrate the textured surface of the upper face; and  
         [0027]    [0027]FIG. 8 is a flow diagram describing assembling the spring assembly utilizing the leaf spring insert of the present invention.  
         [0028]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0029]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0030]    Referring to the drawings, with specific reference to FIGS. 1 and 2, the leaf spring insert according to the teachings of the present invention is indicated generally with reference numeral  10 . The leaf spring inserts  10  are shown operatively located near the outer edge of a leaf spring  50  in a conventional leaf spring assembly  12  comprising individual leaf springs  13 ,  14 ,  15 ,  16 , and  17  as illustrated in FIG. 1. The uppermost leaf spring  17  includes attachment points  8  at the outer ends. A suitable fastener (not shown) connects attachment points  8  to the frame of the vehicle. Attachment point  9  is located at the centerpoint of spring  13  and connects each spring at the respective centerpoint. A fastener (not shown) suitably connects attachment point  9  to an axle of a vehicle and ultimately acts as the point where the wheel input force of the vehicle suspension system is realized. In the exemplary illustration, eight leaf spring inserts would be utilized to sufficiently separate the engagement surfaces of the individual leaves  13 ,  14 ,  15 ,  16 , and  17 . In a typical vehicle having two leaf spring assemblies, sixteen inserts would be utilized. More or fewer inserts may be incorporated depending upon the desired configuration, number of springs, and engagement surfaces.  
         [0031]    Turning now to FIGS. 2 and 3, the leaf spring insert  10  includes a body or base portion  20 , stem portion  30 , and an insert pin  40 . The stem portion  30  includes a plurality of fingers or arms  32  that expand to accept insert pin  40 . An aperture  58  is formed through leaf spring  50  and receives the stem portion  30  of spring insert  10 . Ribs  34  of fingers  32  arranged radially extend radially outward to grip the inner wall  56  of aperture  58  as insert pin  40  is inserted through central bore  31  of stem portion  30 . Body  20  concludes an inner face  22  which engages inner surface  57  of leaf spring  50 .  
         [0032]    The body  20 , stem portion  30 , and insert pin  40  are manufactured as one piece through a molding procedure. The configuration of the resultant molded piece is best shown in FIG. 2. The contact between insert pin  40  and stem portion  30  is such that the pin  40  may be detached from the stem portion  30  by an impact force, such as an impact by a hammer or other object. Detaching insert pin  40  enables insertion of insert pin  40  into stem portion  30  through central bore  31  formed by the fingers  32 . Insert pin  40  has a tapered outer diameter such that finger portions  32  expand as the insert pin  40  is slidably introduced into central bore  31 .  
         [0033]    Referring to FIG. 4, the leaf spring insert  10  is shown inserted through aperture  58  of leaf spring  50  prior to detaching insert pin  40 . Insert pin  40  includes a lower flared section  42  and an upper flared section  44 . Lip  43  separates flared sections  42  and  44  of insert pin  40  and retains insert pin  40  once it is sufficiently inserted into central bore  31  of stem portion  30 . Lip  43  is retained by ridge  29  formed along a circumferential inner surface of fingers  32 .  
         [0034]    Base  20  of leaf spring insert  10  includes an outer face  23 . Surface  23  includes circular protrusions  27 , best shown in FIG. 7, that engage surface  63  of opposing leaf spring  60 . As the wheel configured to cooperate with the associated leaf spring assembly encounters a force normal to the road surface, the individual leaf springs of the leaf spring assembly flex upward and downward with respect to the attachment points. The elliptical deflection causes surface  23  to slidably engage surface  63  of opposing leaf spring  60 .  
         [0035]    [0035]FIGS. 5 and 6 illustrate assembly of leaf spring insert  10  and spring  50 , with stem portion  30  inserted into and through aperture  58 . Fingers  32  extend completely through and beyond aperture  58 . The flared section  42  of insert pin  40  tapers to a smaller outer diameter than flared section  44  which improves the axial retention force at protruding end  68 . The cooperation between lip  43  with ridge  29  and the increased axial force supplied by flared section  44  on ribs  34  of fingers  32  provides adequate retention needed to secure leaf spring insert.  
         [0036]    Turning now to FIG. 7, circular protrusions  27  are extended from surface  23  of the body  20  to allow paints and sediments worn away from an adjacent spring to escape before a flush surface to surface contact is realized between surface  23  of body  20  and surface  63  of leaf spring  60 .  
         [0037]    [0037]FIG. 8 depicts a flow diagram  70  for assembling a spring assembly using the spring insert of the present invention. The assembly process begins at start block  72  and proceeds to process block  74 . At process block  74 , the spring insert is molded as a one piece unit as described above, preferably through an injection molding process. Control then proceeds to process block  76  in which the stem and attached insert pin are placed into an aperture of a spring to which the insert will be attached. At process block  78 , the insert  10  is struck using an impact tool, such as a hammer, to detach the insert pin from the stem, causing the insert pin to enter the central bore of the stem. Preferably, the insert pin includes a shoulder or a lip which engages a corresponding ridge in the central bore of the stem in order to retain insert pin within the stem, thereby causing the fingers to protrude outwardly, thereby increasing interference fit with the attached spring. Once the inserts are formed in the individual springs, individual springs are then assembled in the spring assembly, as shown at process block  80 . Control then terminates at process block  82 .  
         [0038]    While the invention has been described in the specification and illustrated in the drawings with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention as defined in the claims. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out this invention.

Technology Classification (CPC): 1