Abstract:
A link of a top stack linkage for a convertible top of a vehicle is presented for immediate incorporation in a top stack linkage. The link is molded as a spine having a main body portion and an offset portion, and one or more lateral structural members including at least one reinforcing rib. The molding forms a unitary pivot link, installed in the top stack linkage as molded, to reduce finishing of the parts, and reducing fabrication time and linkage weight from known top stack linkage configurations. A method of manufacturing includes providing a mold defining an interior cavity that defines the shape of a pivot link, injecting molten magnesium into the mold, and molding the molten magnesium to form a spine and at least one of a plurality of lateral structural members that form a monolithic pivot link.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a division of U.S. application Ser. No. 12/252,102 filed Oct. 15, 2008, which, in turn, claims the benefit of U.S. provisional Application No. 60/979,922 filed Oct. 15, 2007, the disclosures of which are incorporated in their entirety by reference herein. 
     
    
     BACKGROUND 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a link for an articulated linkage, such as a convertible top stack linkage, that is formed by injection molding magnesium to form a link with integral reinforcing ribs, integral pivot pins and integral bushings. 
         [0004]    2. Background 
         [0005]    Vehicles may be provided with roofs that are movable between an extended position and a retracted position, such as convertible tops and retractable hardtops. These types of vehicle roofs are generally constructed to be moved between the extended and retracted position on an articulated linkage that is commonly referred to as a top stack linkage. It has previously been proposed in the Applicant&#39;s assignee&#39;s PCT application Serial No. PCT/US2005/006522, filed Feb. 28, 2005 to form parts of the bows and rails of the top stack with an injection molded magnesium forming process. The prior application disclosed the use of stamped metal links to interconnect the side rails and bows of the top stack. Some of the links also incorporated tubular portions that were formed into required shapes and provided with end fittings to secure the links to the side rail, other links and bows. 
       SUMMARY 
       [0006]    One aspect of the present invention is to provide an operational link of a top stack linkage for a convertible top of a vehicle. The link includes a spine extending through a length and a width of the link and may have a first side and a second side. The spine may have a main body portion and an offset portion. The offset portion is offset relative to the main body portion. The link further includes a plurality of reinforcing ribs integrally molded to the spine and extending from at least one of a first side or a second side of the link. The plurality of reinforcing ribs may also extend through the length and width of the spine. In one embodiment, the plurality of reinforcing ribs may extend from both the first and the second side of the link. The operational link further includes a plurality of lateral structural members integrally molded with the spine. The spine, the plurality of reinforcing ribs, and the lateral structural members may form a single and unitary link. 
         [0007]    In some embodiments, the link may have a front portion and a back portion that define planar flange portions of the pivot link. The front portion and the back portion may lack reinforcing ribs 
         [0008]    In other embodiments, the plurality of lateral structural members of the operation link may include a plurality of bushings. At least one of the plurality of bushings may include a plurality of radially extending ribs interconnected by a circumferentially extending rib for reinforcing the at least one bushing. 
         [0009]    In other embodiments, the plurality of lateral members of the operational link may include a peripheral wall and a plurality of integral pins. As such, the operation link may further include a pivot flange extending outwardly from the peripheral wall. The pivot flange may support at least one of the plurality of integral pins. The plurality of lateral structural members may include a plurality of ribs extending vertically from the link which reinforce the pivot flange. The peripheral wall may have one or more attachments secured to the peripheral wall by a fastener. For example, the one or more attachments may be a top support strap and the fastener may be a threaded fastener, rivet, or pin. The peripheral wall may have a fastener receptacle hole for securing the fastener to the peripheral wall. 
         [0010]    Another aspect of the present invention provides for a method of manufacturing a link of a top stack linkage for a convertible top of a vehicle. The method includes providing a mold defining an interior cavity that defines the shape of a pivot link. The method further includes injecting molten magnesium into the mold. The method further includes molding the magnesium injected mold to form a spine. The spine may have a plurality of lateral structural members that are integrally molded with the spine to form a single and unitary link. In one embodiment, the spine has a main body portion and at least one offset portion that is not coplanar relative to the main body portion. 
         [0011]    In some embodiments, the plurality lateral structural members may include a plurality of reinforcing ribs. Accordingly, the method may further include molding the plurality of reinforcing ribs to reinforce the pivot link and maintain a spatial orientation of the offset portion relative to the main body portion. 
         [0012]    In other embodiments, the pivot link may include a front portion and a back portion that define planar flange portions of the pivot link. Accordingly, the molding step may further include forming the planar flange portions for permitting a plurality of adjacent links to pivot relative to the pivot link. 
         [0013]    In other embodiments, the plurality of lateral structural members may include a plurality of pins disposed at spaced locations on the spine. Accordingly, the method may further include connecting a plurality of links and a plurality of bows to the pivot link. 
         [0014]    In other embodiments, the plurality of lateral structural members may include a plurality of bushings disposed at spaced locations on the spine. The plurality of bushings may be reinforced by a plurality of radially extending ribs interconnected by circumferentially extending ribs. Accordingly, the method may further include inserting a plurality of pins in the plurality of bushings for connecting adjacent links to the pivot link. 
         [0015]    Another aspect of the present invention provides for an operational link of a top stack linkage for a convertible top of a vehicle. The operation link includes a spine extending through a length and a width of the link. The link may have a first side and a second side. The spine may also have a main body portion and an offset portion. The offset portion is offset relative to the main body portion. The operation link further includes a plurality of reinforcing ribs extending from at least one of the first side or second side of the link. The reinforcing ribs may further extend through a length and width of the spine. In one embodiment, the plurality of reinforcing ribs may be varied in length. 
         [0016]    The operation link further includes a plurality of pins integral with the spine. The pins may be disposed at spaced locations on the spine for securing a plurality of other links and bows to the link. The operation link further includes a plurality of bushings integral with and disposed at spaced locations on the spine for connecting the link to a plurality of other links. The plurality of bushings may be reinforced by a plurality of radially extending ribs interconnected by circumferentially extending ribs. The operation link further includes an interior receptacle boss located at the offset portion of the spine. The boss may be supported about its periphery by a plurality of reinforcing ribs. The operational link further includes a peripheral wall substantially extending around the periphery of the link. The spine, the plurality of reinforcing ribs, the plurality of pins, the plurality of bushings, the interior receptacle boss, and the peripheral wall may be formed as a single and unitary pivot link. 
         [0017]    These and other aspects of the present invention will be better understood in view of the attached drawings and following detailed description of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further object and advantages thereof, may best be understood with reference to the following description, taken in connection with the accompanying drawings, which: 
           [0019]      FIG. 1  is a side elevation view of a prior art convertible top and top stack linkage made with fabricated operational links; 
           [0020]      FIG. 2  is a perspective view of a prior art pivot link that is stamped, machined and assembled in accordance with a prior art manufacturing method; 
           [0021]      FIG. 3  is a side elevation view of a control link made according to one embodiment of the present invention; 
           [0022]      FIG. 4  is a perspective view of the control link made according to one embodiment of the present invention; 
           [0023]      FIG. 5  is an inverted perspective view of the control link made according to one embodiment of the present invention; 
           [0024]      FIG. 6  is a cross-sectional view taken along the plane of section of line  6 - 6  in  FIG. 3 ; 
           [0025]      FIG. 7  is a cross-sectional view taken along the line of section of line  7 - 7  in  FIGS. 3 ; and 
           [0026]      FIG. 8  is a cross-sectional view taken along the plane of section of line  8 - 8  in  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. 
         [0028]    By way of background, the top stack linkage disclosed in Applicant&#39;s prior co-pending application will be generally described. Referring to  FIG. 1 , a convertible top  10  is illustrated, including a top stack  12 . The convertible top  10  includes a one bow  14  that is adapted to be secured to a windshield header  16 . Moving rearwardly from the one bow, the other bows of the top stack  12  are identified as a two bow  18 , a three bow  20 , a four bow  22  and a five bow  24 . The bows support a top cover  26  and extend transversely relative to the vehicle when the convertible top  10  is in its extended position. The two bow  18 , three bow  20  and four bow  22  are assemblies including extruded portions and injection molded magnesium portions. The one bow  14  is integrally formed with the front rail (not shown) which is connected to a center rail  32 . The center rail  32  is articulately connected to rear rail  34 . The one bow  14 , front rail, side rail  32  and rear rail  34  all may be formed as injection molded magnesium parts. The rails define a portion of the perimeter of the convertible top with the top cover fabric being secured to the rail to provide a tight fitting convertible top. 
         [0029]    In the prior implementation of this convertible top, it was believed to be necessary to form the operational links of the top stack as either stamped parts or formed tubular parts to obtain parts having the desired durability in a cost-effective manner. For example, the control link  36 , pivot link  40 , pressure link  42  and balance link  44  were all previously formed with either a metal stamping operation or tube forming and welding process. The cost associated required for stamping steel plate, hydroforming tubular members and welding adds to the cost of the parts. Also, the pivot points in many instances required machining operations and separate bushings that also added to the cost of the entire assembly. Assembling the parts together with separate pins required careful alignment of the pins and an intricate assembly procedure. Close tolerances must be met to provide a top stack linkage that can be reliably and repeatedly assembled without complications resulting from tolerance stack up. 
         [0030]    Referring to  FIG. 2 , a perspective view of the pivot link  40  is provided. The prior art pivot link is a complicated part that is critical to operation of the top. The pivot link  40  has a main body portion  46  that is generally formed to lie in a single plane. An offset portion  48  is offset from the plane of the main body portion  46 . A pivot pin  50  is provided for connecting the front end of the pivot link to the control link  36 . A tubular receptacle  52  is provided on the pivot link  40  that receives a fastener (not shown) for connecting the control link to the rear rail  34 . A pin  54  is secured to the rear portion of the pivot link  40  which connects the pivot link  40  to the pressure link  42 . In addition, a three bow opening  56  and four bow opening  58  are provided on the pivot link  40  for attachment to the three bow  20  and four bow  22 , respectively. To assure proper operation of the top  10 , five connection points on the pivot link  40  must conform to closely held tolerances. To assure such close tolerances, the orientation of the main body portion  46  relative to the offset portion  48  must be precisely aligned when initially manufactured. Through use, stamped parts and formed tubular members may be bent if the top is impacted by a foreign object, either from a source external to the vehicle or in the course of extending or retracting the convertible top. Any distortion of the formed part may complicate, or interfere with, proper operation of the top  10 . The present invention is directed to overcoming the problems identified above in regard to the prior top, and more specifically, with regard to the operational links thereof. 
         [0031]    Referring to  FIGS. 3-5 , a monolithic pivot link  100  is illustrated as an example of an operational link of a top stack linkage that may be made in accordance with the present invention. It should be understood that other operational links, including, but not limited to the links that would replace the prior art pressure link  42 , balance link  44  and other operational links, may be manufactured including various combinations of the structural elements of the monolithic pivot link  100 . The pivot link  100  includes a spine  102  in the form of a wall that extends through the length and width of a substantial portion of the pivot link  100  as shown in  FIGS. 3-5  and  6 - 8  at the end of the lead line for spine  102 . A plurality of reinforcing ribs  104  extend from one or both sides of the wall extending through a substantial portion of the pivot link  100 . The length, thickness, shape and orientation of the reinforcing ribs  104  may be varied depending upon the structural requirements of the pivot link  100 . These parameters may be varied depending upon the space available within the top stack linkage structure to allow for clearance of relatively movable parts of the top stack linkage. Planar flange portions  106  may be provided as required to permit adjacent links to pivot relative to the pivot link  100 . Such planar portions  106  may be provided where no reinforcing ribs are required in the planar flange portions  106 . 
         [0032]    Integral pins  108  may be provided at desired locations where other links and bows are secured to pivot link  100 . The integral pins  108  are formed to net size and shape in precisely located positions to assure easy assembly and smooth operation of connected parts. 
         [0033]    Integral bushings  110  may be formed on the pivot link  100  at desired locations to receive pins that connect the pivot link  100  to adjacent links and supporting structures. Integral bushings  110  are formed to net size and shape at desired locations precisely and without need for additional machining or surface finishing to provide a finished part because the pivot link  100  is formed of magnesium in an injection molding process. 
         [0034]    With particular reference to  FIG. 4  and continued reference to  FIGS. 3 and 5 , one of the integral bushings  110  is shown to include a plurality of radially extending ribs  116  that are interconnected by a circumferentially extending rib  118 . The radially extending ribs  116  and circumferentially extending rib  118  reinforce the integral bushing  110 . 
         [0035]    A pivot flange  120  supports integral pin  108 . The pivot flange  120  is reinforced by triangular ribs  122 . The triangular ribs  122  reinforce the opposite side of the pivot flange  120  from the pin  108 . The pivot flange  120  extends outwardly from a peripheral wall  124  of the pivot link  100 . 
         [0036]    The peripheral wall  124  extends substantially around the entire periphery of the pivot link  100 . The peripheral wall  124  provides additional reinforcement and a smooth exterior for the pivot link  100 . 
         [0037]    An interior receptacle boss  128  is provided that is supported about its periphery by reinforcing ribs  104 . The interior receptacle boss  128  will be further described below with reference to  FIG. 8 . 
         [0038]    The term “lateral structure members” as used in this disclosure generally refers to protrusions that extend laterally, or in the cross-car direction from the spine  102 . Examples of lateral structural members may include one or more of the following: reinforcing ribs  104 , pins  108 , bushings  110 , radially extending ribs  116 , circumferentially extending ribs  118 , triangular ribs  122 , peripheral wall  124 , or receptacle boss  128 . 
         [0039]    A top support strap  130  is shown in  FIGS. 3 and 4 . The top support strap  130 , or other types of attachments, may be secured to the peripheral wall  124  of the pivot link  100  by a fastener  132 . The fastener  132  may be a pin that is secured to the fastener receptacle hole  112 . The fastener  132  may be a threaded fastener, rivet or pin. The fastener  132  may be secured within the fastener receptacle hole  112  by a press-on spring nut (not shown) to facilitate assembly. 
         [0040]    With particular reference to  FIG. 5  and continued reference to  FIGS. 3 and 4 , the monolithic pivot link  100  may include a main body portion  136  of the spine  102 . In addition, an offset portion  138  of the spine  102  may be provided as part of the pivot link  100 . The offset portion  138  is disposed in a plane that is offset relative to the plane of the main body portion  136 . Multiple offset portions  138  may be provided along the spine  102 . The reinforcing ribs  104  function to reinforce the pivot link and also maintain the spatial orientation of the offset portion  138  relative to the main body portion  136 . 
         [0041]    Referring to  FIG. 6 , a section is taken through the main body portion  136 . An integral pin  108  is shown extending from a planar flange portion  106 . In addition, reinforcing ribs  104  are shown extending from one side of the main body portion  136 . The reinforcing ribs  104  may extend from the spine  102  to a varying extent as required to locally reinforce the spine  102 . The integral bushing  110  shown in  FIG. 6  is reinforced by radially extending ribs  116  that serve to reinforce and fix the position of the inner bushing  110 . 
         [0042]    Referring to  FIG. 7 , a different section is taken through the pivot link  100  in the main body portion  136  of the spine  102 . The reinforcing rib  104  is shown on the left side of  FIG. 7  that is substantially longer than the reinforcing rib shown on the right side of  FIG. 7 . The ability to vary the length of the reinforcing ribs  104  permits reinforcement of the spine  102  to a greater or lesser extent depending upon the clearance available on either side of the spine  102 . The peripheral wall  124  is also shown in  FIG. 7  which reinforces the periphery of the spine  102 . 
         [0043]    Referring to  FIG. 8 , a section is taken through the offset portion  138  of the spine  102  of the link  100 . An interior receptacle boss  128  is shown that is supported by reinforcing ribs  104 . The interior receptacle boss  128  provides a blind opening in one side of the pivot link  100  in which a screw or other fastener may be secured. A reinforcing rib  104  may be provided on the opposite side of the spine  102  from the interior receptacle boss  128 . The peripheral wall  124  reinforces the spine in the offset portion  138  on both sides of the interior receptacle boss  128 . 
         [0044]    The monolithic pivot link  100  is formed in an injection molding process in which molten magnesium is injected into a mold. The mold defines an interior cavity corresponding precisely to the net size and shape of the pivot link  100 . The injection molding process permits the spine  102 , including its main body portion  136  and offset portion  138 , to be molded in a single step. Reinforcing ribs  104 , planar flange portions  106 , integral pins  108 , and integral bushings are also formed as a single part that is integral with the spine  102 . Fastener receptacle holes  112  may be formed without the need to drill or machine the pivot link after the molding step. 
         [0045]    The manufacturing process may be applied to other operational links, as previously indicated, with design flexibility being obtained by defining the required planes of the spine  102  and then reinforcing one or both sides of the link using variable length reinforcing ribs. Joints in the link may be provided in the form of bushing or pins that are integrally formed on the link. 
         [0046]    According to the magnesium injection molding process described herein, a durable and extensively reinforced operating link may be provided that has precisely located pins, bushings and other connection points that require no machining. The link made according to the process results in substantial cost savings as a result of reducing the number of parts and manufacturing steps required to provide a robust link that may be adapted to a wide variety of link designs. 
         [0047]    While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.