Abstract:
The present invention is a composite transmission selector lever that avoids the multiple manufacturing steps of current levers and in addition gives a reduction in cost. The lever comprises an elongated, structural element that defines an open interior. An electrically conductive wire for a switch is installed into the open interior. Molding material is applied around the structural element, thereby creating a layered construction with molding material on the outside of the structural element.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
       [0001]    The present application is a Continuation-In-Part of U.S. patent application Ser. No. 11/419,827, filed May 23, 2006 entitled COMPOSITE LEVER AND METHOD OF MAKING SAME, which is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to levers and more specifically to improvements in how such levers are made. 
         [0003]    Over the centuries, levers have been an essential part of any activity in which mechanical devices are controlled, actuated, manipulated, and the like. Usually, a lever consists of a base connecting to some part of the machinery, such as a linkage, a shaft which is either straight or bent according to the application and an operator handle to enable ergonometric and efficient grasping of the lever to induce the proper movement. The lever can be movement through an arc in a single plane or multiple planes, as in a gear shift. In some cases, the lever could even be rotated about its axis for further mechanical output. In recent years, there are many instances in which a lever providing a mechanical output must also provide an electrical output, usually by some form of switch. Levers of this type are most commonly found in the automotive field, although the present invention has an application not so limited by the automotive environment. 
         [0004]    For example, in the field of automatic transmission equipped vehicles designed to tow a boat or trailer, it is necessary to disable an automatic overdrive feature when towing. The transmission shift lever includes a base and an operator handle on which an electrical switch is attached to de-activate the overdrive control in the transmission control system. Thus, operation of the lever consists of physically moving the lever to engage gears/clutches and then electrically activate a solenoid or other device to activate or de-activate the overdrive control. Existing transmission selector levers are expensive machined assemblies requiring a solid shaft to provide the appropriate bending strength and a drilled hole extending through a substantial portion of the shaft. The through hole receives an electrical conductor that extends from a connector at the base of the lever to a switch assembly in the operator handle. This assembly requires machining and multi-steps to achieve a final product. Replacing the shaft with a thick-walled tubing to achieve the deflection strength reduces cost to some extent, but is still costly because thick-walled tubing is expensive to make. The use of these shafts is more problematic when the shaft must be bent, frequently in multiple places, to accommodate functional and operator ergonomic requirements. After the bending is completed, the wire must be threaded through the shaft. Because the hole is drilled, a subsequent and further step in fastening the switch terminal and/or connector must take place. Finally, the shaft must be painted or over-molded to match the handle color. 
         [0005]    Another alternative to forming the lever is to cast it from some form of plastic. Although this may simplify the manufacturing process when dealing with complex multiple bends and complex shapes, it does not have the requisite strength necessary to provide force input for devices like those used in transmissions. 
         [0006]    Thus, a need exists in the art for a lever that has the capability of being economically formed but at the same time meeting structural integrity requirements. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    In one form, the invention comprises an elongated structure having longitudinal edges. In another form, a tubular sleeve or tube is used for the elongated structure. The elongated structure is constructed and arranged so as to define an open interior. In the one form, the structure has a cross sectional configuration such that the interior walls are spaced from each other to form the open interior. In the other form, the tubular sleeve is closed with a generally circular cross section. Structural material is over-molded and can also be used to at least substantially fill the open interior, whereby the elongated structure and the molded structural material combine to reinforce one another, with either construction. 
         [0008]    In yet another form, the invention comprises a method for forming a lever comprising the steps of providing an elongated structure defining an open interior. Structural material is over-molded and can also be used to at least substantially fill the open interior of the elongated structure whereby the elongated structure and molded material combine to reinforce one another, with either construction. 
         [0009]    One object of the present invention is to provide a lever that is significantly less costly to manufacture, but which has the required strength for mechanical outputs. 
         [0010]    Related objects and advantages of the present invention will be apparent from the following description. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0011]      FIG. 1  is a top view of a lever embodying the present invention. 
           [0012]      FIG. 2  is a longitudinal section view of the lever of  FIG. 1  taken on lines  2 - 2  of  FIG. 1 . 
           [0013]      FIG. 3  is a cross sectional view of the lever shown in  FIGS. 1 and 2  taken on lines  3 - 3  of  FIG. 2 . 
           [0014]      FIG. 4  is a cross sectional view of the lever shown in  FIGS. 1 and 2  taken on lines  4 - 4  of  FIG. 2 . 
           [0015]      FIG. 5  is a side view of the lever of  FIGS. 1 and 2  taken on lines  5 - 5  of  FIG. 1 . 
           [0016]      FIG. 6  is a perspective view of one of the components of the lever of  FIG. 1  in an intermediate assembly position. 
           [0017]      FIG. 7  is a perspective view of the component of  FIG. 6  but in a later assembly position. 
           [0018]      FIG. 8  is a fragmentary side view of an alternative form of one of the components of the lever of  FIG. 1 . 
           [0019]      FIG. 9A  is an elevational view, in full section, of a lever assembly according to another embodiment of the present invention. 
           [0020]      FIG. 9B  is an elevational view of the  FIG. 9A  lever assembly. 
           [0021]      FIG. 9C  is an elevational view of the  FIG. 9A  lever assembly. 
           [0022]      FIG. 9D  is a perspective view of the  FIG. 9A  lever assembly. 
           [0023]      FIG. 10  is a front elevational view of a hollow, cylindrical tube comprising one portion of the  FIG. 9A  lever assembly. 
           [0024]      FIG. 11A  is an elevational view, in full section, of the  FIG. 10  tubular sleeve, as formed for use as part of the  FIG. 9A  lever assembly. 
           [0025]      FIG. 11B  is an elevational view of the  FIG. 11A  tubular sleeve arrangement. 
           [0026]      FIG. 12A  is a front elevational view of a base component that is assembled into the  FIG. 10  tubular sleeve, as illustrated in  FIG. 11A . 
           [0027]      FIG. 12B  is a side elevational view of the  FIG. 12A  base component. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0028]    For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. 
         [0029]      FIG. 1  shows a lever generally indicated by reference character  10 . Lever  10 , by way of example, is used as a transmission selector lever. However, it could be employed for any one of a multitude of functions providing a mechanical output. Lever  10  comprises a base  12  shown herein as cylindrical and having a through hole  14  for appropriate connection to a transmission selector mechanism. Base  12  is a separate, independent component part that is securely assembled into element  22 . This is in contrast to prior art constructions that gun drill a solid rod and machine the base as a unitary portion. 
         [0030]    Lever  10  has a shaft section generally indicated by reference character  16  and an operator handle  18  containing a switch assembly  20 . As described below, the lever has the function of movement to place a transmission into gear and, at the same time, the switch assembly  20  is engaged when certain conditions are experienced, such as towing. The shaft assembly  16  comprises an elongated structural element  22  extending from base  12  to handle assembly  18 . Elongated structural element  22 , as illustrated, is formed by stamping sheet metal of appropriate thickness and strength into a shape that will be described in detail later. The elongated element  22  receives a wire generally indicated by reference character  24  which extends from a location adjacent base  12  to the switch assembly  20 . As described below, the shaft assembly  16  and handle assembly  18  both comprise a structural material  62  that is molded over and around the structural element  22  to achieve significant reductions in manufacturing cost. The resulting lever fully meets the strength requirements that were heretofore met by solid steel shafts, drilled to receive a wire before assembly, and thick wall tubing shafts. 
         [0031]    Referring to  FIG. 5 , the base  12  is constructed and arranged to be received in the base end  26  of the structural element  22 . As stated previously, the structural element  22  is formed from sheet metal of appropriate thickness and strength to achieve the structural requirements of the application. One example of material that may be used for this is 0.060 inch  1018  to  1020  cold rolled steel (CRS). However, it should be apparent to those skilled in the art that many other forms of sheet material may be employed for this purpose. The structural assembly  22  starts out generally as a flat, elongated sheet element. Through a series of hits in a progressive die, it is formed into the shape shown in  FIG. 5 . That shape involves longitudinal edges  28  and  30  positioned closely adjacent one another as shown in  FIG. 5 . As shown in  FIG. 4 , longitudinal edges  28  and  30  are formed by curving structural element  22  over along a longitudinal side  32  to form, in a general sense, a triangular shape. The longitudinal edges  28  and  30  are curved in towards longitudinal line  32  at sections  34  and  36 . As is apparent from  FIG. 4 , this manner of folding the structural element  22  causes interior walls  38  and  40  to be spaced from one another, thereby forming an open interior  42  for the structural element  22 . The longitudinal edges  28  and  30  are spaced from one another in  FIG. 4  to permit sideways insertion of the wire  24  into the open interior  42  of the structural element  22  and sometimes adjacent to line  32 . Although the longitudinal edges  28  and  30  are spaced from one another, it should be apparent to those skilled in the art that if the lever is to be used without a wire assembly through the interior, the edges may be closer to one another and may even touch and/or interlock, as described below. In another embodiment, as disclosed herein, the structural element is seam-welded and drawn and finished into the closed cylindrical tube or tubular sleeve as illustrated in  FIGS. 9A-12B . 
         [0032]    As illustrated in  FIG. 4 , the cross section configuration of structural element  22  is generally triangular in shape and, with the curved section adjacent the longitudinal edges  28  and  30 , is generally heart-shaped. This is done to contribute maximum strength to the ultimate structure. It is, however, one of the many forms that may be employed for the longitudinal structural element  22 . One objective in the construction of element  22  is to be bent over on itself to form a shape that has an open interior and which is capable of being overmolded, as discussed below in detail. This desired open interior is provided by the tubular sleeve for the structural element as illustrated in  FIGS. 9A-12B . 
         [0033]    Referring now to  FIGS. 5 ,  6 , and  7  and  FIG. 3 , the structural element  22  makes a transition  45  from the generally triangular shape shown in  FIG. 4  to a cylindrical shaped section  44  shown in  FIG. 5  and in  FIG. 3 . This transition  45  to the cylindrical shape is so that the exterior of structural element  22  at its base end  26  conforms to the outer shape of base element  12 . As illustrated, the received end of base element  12  is cylindrical and the end of structural element  22  is cylindrically shaped to conform to its surface. It should be apparent, however, that base element  12  may be provided in any one of a number of configurations and that structural element end section  44  may be formed to conform to those configurations. Base element  12  has a pair of circumferential grooves  46  so that structural element  22  may be crimped at  48  (shown in  FIG. 2 ) to connect the structural element  22  to base  12 . Although crimping is illustrated, the fastening may take place using a variety of techniques, including welding, press-fit or interference fit and adhesives, etc. 
         [0034]    As shown in  FIG. 5 , structural element  22  has a first bend at  50  and a second bend at  52 . This is done for operator ergonomics to place the lever in such a position that it permits convenient manipulation. It should be apparent to those skilled in the art that the element  22  may be formed as a straight section, with one bend, or with more than two bends, as the application requires. The current capability of stamping techniques easily allows the formation of a structural element with the cross sectional configurations shown in  FIGS. 3 and 4  and maintaining uniform structural and minimum bowing of the material. The structural element has the cross section of  FIG. 4  from beyond the cylindrical section to an upper end  54 . 
         [0035]    The structural element  22  shown in  FIGS. 5 ,  6 , and  7  has an approximate triangular cross sectional shape and has longitudinal edges that leave a gap for the sideways insertion of the wire  24 . The longitudinal edges of the elongated structural element can be formed to be closer than that and even abut one another, as shown in  FIG. 8 .  FIG. 8  shows an alternative longitudinal structural element  72  having longitudinal edges  74  and  76  which abut one another after the forming process is complete. Longitudinal edges  76  and  74  may be locked together by a series of notches  78  in longitudinal edge  74  and interfitting tabs  80  in longitudinal edge  76 . The elements are then locked together similar to that found in a crossword puzzle. Since the edges  74  and  76  abut one another, it is necessary to lay the wire  24  into the interior of the structural element  72  prior to the final forming process of joining the longitudinal edges together. The completed structure is then overmolded with structural material, as in the embodiment shown in  FIGS. 1-7 . It should be noted that a plurality of holes  82  are formed in structural element  72  to obtain more uniform distribution of the molding material. 
         [0036]    As shown in  FIG. 5 , the wire  24  is laid into the gap between the longitudinal edges  28  and  30 . This allows for several advantages. The first is the ease with which the wire can be laid into the interior of the structural element  22  and the second is that the wire may have a preassembled connector  56  of significant proportions that would not permit threading through passages as drilled in the prior art and a preassembled switch terminal  58  positioned adjacent the upper end  54  of the structural element  22 . To enable the molding process set out below, a tubular element  60  is provided over the wire  24  adjacent one end of base element  12  to provide definition for the mold as the wire exits the space between the longitudinal edges  28  and  30  adjacent base element  12 . 
         [0037]    The assembly of the wire  24  and the structural element  22  and other parts is placed into a mold and then a structural material is molded over the exterior of structural element  22  to provide a uniform external cross section. As one option, structural material can be molded into the interior  42  of structural element  22 . As shown in  FIG. 3 , that cross section location is circular. However, it should be noted that many different forms of exterior shapes can be formed. The outlines of the structural molded material  62  are shown in phantom in  FIG. 5  and designated by reference character  62 . The molded structural material  62  forms an integral outer structure for the section  16  and also for the handle  18 . Structural material  62  may be any form of moldable material that optionally fills the interior  42  of structural element  22  to form a resultant structure that has superior structural integrity compared to a structural element  22  and structural molded material  62  separately. One example of such a material for the molded structural material  62  can be a thermoplastic of 40% glass and mineral filled nylon or polyamide  6 . It should be apparent to those skilled in the art that thermoplastic materials suitable for applications in this environment are constantly changing and that the structural material  62  may be formed from then-current materials that are available. The polyamide  6  has relatively low mold shrinkage and good fatigue resistance. It has a melting temperature range of approximately 230-280 degrees C. Because of the elevated temperature range for the molded material  62 , the wire  24  requires an electrical insulation material that has a melting point higher than that for the molded material  62 . A suitable material for insulating wire  24  is Teflon, although other high temperature materials may be employed. 
         [0038]    Once the material  62  is over-molded, the structure shown in  FIGS. 1 and 2  is the result. It can be seen that the normal features of the operator handle  18  making it suitable for operator manipulation are formed. These include axially extending ribs  64  positioned around the circumference and a plurality of axially extending recesses  66  positioned around the circumference of the handle. The switch terminal  58  receives a switch  68  that has an operator manipulated button  70  biased to an open position and can be depressed to establish electrical contact between the wires  24  and thus provide control input to the transmission. 
         [0039]    The resultant lever offers significant manufacturing economies because the process of providing a passage through the handle portion  16  from the operator handle  18  is already provided in the forming of the structural element  22 . Connecting the structural element  22  to the base  12  is a process that is easily automated and capable of a variety of fastening approaches to form an effective interconnection. The molding process by which the structural molded material  62  is over-molded over the exterior is also easily automated and, in one process, establishes a final product with a finish that meets customer requirements in its as-molded state. An added option is to mold material  62  into the interior of structural element  22 . The only remaining step in the process is to insert the switch assembly  68  into the operator handle. The resultant structure easily meets the strength requirements for such a lever in terms of bending, appearance, and other form and fit functions. By configuring base  12  as a separate component to be assembled into element  22 , greater design versatility is provided as contrasted to a unitary machining. Lower cost also results from this new construction technique. 
         [0040]    Referring now to  FIGS. 9A-12B , another embodiment is disclosed and illustrated. The lever  110  (see  FIGS. 9A-9D ) is constructed and arranged in a manner that is the same as lever  10 , except for the shape and construction of elongated structural element  122  which receives tail pin or base  112  as is illustrated in  FIGS. 11A and 11B . Not all of the structural details of lever  110  have been illustrated since their construction, arrangement, and function are virtually the same as the counterpart components of lever  10 . Included as part of lever  110  is an operator handle  118  and shaft assembly  116 . 
         [0041]    Referring to  FIG. 10 , the starting form of structural element  122  is illustrated. Structural element  122  is seam-welded and drawn and finished into a generally cylindrical tube or tubular sleeve with a generally circular cross section. Structural element  122  is constructed and arranged as an enclosed, hollow tubular sleeve that is open at each end. In the exemplary embodiment, the structural element  122  is used in a lever  110  that is constructed and arranged for use as a transmission shift or selector lever. The cylindrical sidewall  122   a  defines a generally cylindrical, open interior  122   b.    
         [0042]    In order to configure structural element  122  for use as part of lever  110 , the structural element  122  is bent and shaped as illustrated in  FIGS. 11A and 11B . The tail pin or base  112 , as illustrated in  FIGS. 12A and 12B , is inserted into end  122   c  of the structural element  122 . Generally, the construction and arrangement of base  112  corresponds to base  12  and the overall function and use relative to the remainder of the lever are the same for bases  112  and  12 . 
         [0043]    The use of an elongated, tubular or cylindrical sleeve for structural element  122  offers an alternative to the first embodiment and gives the designer another option in terms of cost, convenience, strength, and reliability for the lever construction, exemplified by lever  110 . Since structural element  122  includes (defines) an open interior  122   b , that open interior is able to receive the electrically conductive wire and, if desired as one option, the molding material consistent with what has been described for the first embodiment. The molding material is applied around the outer surface of the structural element  122  (i.e., over-molded). This construction technique of over-molding onto a metal tube results in reinforcement of the lever construction. If the option of adding molding material to the interior is selected, then the alternating lamination of layers, begins first with the molding material, followed by sidewall  122   a , and completed by the molding material. This also creates a reinforcing structure as described herein. Specifically, the elongated structural element  122  and the inner and outer layers of the molding material combine and cooperate with one another to reinforce one another. 
         [0044]    While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.