Abstract:
An interlock device includes a housing and a toggle interlock mechanism with an extendable interlock pin. The interlock device also includes a preassembled switch, an electromechanical device, and a lead frame interconnecting the switch and electromechanical device. The lead frame conductors are formed as one piece, but are separated after assembly into the housing. The conductors and mating components include mating non-releasable contacts that telescope together in a manner that forms a robust assembly and that facilitates automation of the assembly process. A method related to the above is also disclosed.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a shift interlock device, and more particularly to a brake-transmission-shift-ignition (BTSI) interlock device and circuit integrated into a shifter. 
     Brake-transmission-shift-ignition (BTSI) interlock devices and circuits are known in the art, and further it is known to incorporate a toggle mechanism and preassembled switch into such devices. For example, see U.S. Pat. No. 5,759,132 to Osborn, issued Jun. 2, 1998. A known existing BTSI shifter similar to U.S. Pat. No. 5,759,132 is described in the discussion below entitled “Prior Art”. (See FIGS. 1-2 of the present disclosure.) This known existing BTSI shifter includes a preassembled micro switch that is soldered onto a circuit board. The subassembly is then operably positioned in and secured to the handle of a shift lever assembly of a vehicle shifter. However, this shift lever assembly is undesirably expensive, partially because of the cost of the circuit board, but also because of secondary process costs (e.g. soldering, manual placement and attachment within the handle, and electrical connections). Also, circuit boards have quality and warranty concerns because they are not well suited for the vibrations and harsh environments commonly associated with vehicle shifters (e.g. temperature and humidity variations in the passenger compartment associated with day and night, and/or temperature extremes associated with winter and summer, and/or vibrations and with shifting the shift lever and/or associated with traveling at high speeds along a bumpy road and/or when an engine idles). Accordingly, further improvement is desired in this assembly, including reducing component costs and increasing the automation and efficiency of assembly, and improving the durability and robustness of the shift lever assembly. 
     It is also known to use a lead frame in a brake shifter interlock having a toggle mechanism. For example, see Withey U.S. Pat. No. 5,938,562, which discloses a lead frame incorporated into a toggle interlock device. In the Withey arrangement, the lead frame incorporates conductive components forming a switch. But this switch arrangement can have quality problems, since the conductive components are subject to distortions and dimensional variations, wear, and other problems that occur during installation and use and during the wide temperature variations commonly experienced by shifters. This can lead to poor and unreliable operation of the integral switch. It is desirable to incorporate a preassembled switch into a circuit using a lead frame. However, problems still remain in terms of assembly and warranty problems associated with soldering and/or other electrical connections. Also, the problems associated with dimensional inconsistencies and part-handling common in lead frames need to be addressed, as well as the overall ability to automatically assemble the components. 
     Accordingly, a shifter is desired solving the aforementioned problems and having the aforementioned advantages. 
     SUMMARY OF THE INVENTION 
     The present invention includes a shifter for a vehicle having an electrical control circuit. The shifter includes a base, a shift lever pivoted to the base, and an interlock device on one of the base or the shifter that engages an abutment surface on the other. The abutment surface is configured to be selectively engaged by the interlock device to control movement of the shift lever. The interlock device includes a preassembled switch, an electromechanical device, and a lead frame having at least four conductors. The electromechanical device has an interlock member movable to an extended position for engaging the abutment surface and movable to a retracted position for operating the switch and allowing the shift lever to move. The four conductors operably interconnect the switch and the electromechanical device and define a three-prong terminal adapted for electrical connection to the vehicle control circuit for operating the electromechanical device and for signaling to the vehicle control circuit that the interlock member has been operated. 
     In another aspect of the present invention, a preassembled interlock device includes a housing and a toggle interlock mechanism including an extendable pin operably positioned in the housing. The pin is extendable to a position outside the housing for engaging an abutment surface. A preassembled switch, an electromechanical device, and a lead frame are attached to the housing in an arrangement where the electromechanical device operates the switch when the extendable pin is retracted. The lead frame includes at least four conductors operably interconnected to the switch, the electromechanical device, and to a terminal adapted for electrical connection to a control circuit for operating the electrical mechanical device, and for signaling to the vehicle control circuit that the extendable pin has been moved. 
     In still another aspect of the present invention, a method of assembly for an interlock device comprises steps of providing a housing, and positioning a lead frame in the housing. The method further includes operably positioning a toggle interlock mechanism in the housing, the interlock mechanism including an electromechanical device having a pin extendable to a position outside of the housing. The method also includes positioning a preassembled switch in the housing, including electrically connecting the switch to the lead frame. The method also includes electrically connecting the electromechanical device to the lead frame so that the electromechanical device operates the switch when the extendable pin is retracted. The method further includes separating parts of the lead frame to form at least four separate conductors that operably interconnect the switch and the electromechanical device to a terminal adapted for electrical connection to a control circuit for operating the electromechanical device, and for signaling to the control circuit that the interlock member has been extended. 
     In yet another aspect of the present invention, a preassembled interlock device includes a housing having a plurality of protrusions, and a toggle interlock mechanism including an extendable pin positioned in the housing but extendable to a position outside of the housing. The interlock device also includes an electromechanical device attached to the housing, a preassembled switch in the housing including a plurality of first contacts, and a lead frame having at least four conductors including a plurality of second contacts. When the electromechanical device is energized, it retracts the pin and operates the switch. The first contacts are positioned and oriented to telescopingly engage the second contacts during assembly. The second contacts each include a mechanical retainer that retains the first contacts in operable engagement with the second contacts and further they are adapted to electrically operably interconnect the electrical mechanical device to a control circuit for operating the electrical mechanical device. The lead frame further includes a plurality of location holes with retaining tines that engage the housing protrusions to non-releasably and accurately locate the lead frame in the housing. 
     In still another aspect of the present invention, a shifter for a vehicle having an electrical control circuit includes a base component, a shift lever component operably positioned on the base component, and an interlock device on one of the base and shift lever components. The interlock device is configured and adapted to selectively engage an abutment surface on the other of the components for interlocking the shift lever in a selected gear position. The interlock device includes a preassembled switch and a lead frame, with the preassembled switch having at least three first contacts and the lead frame having at least three second contacts engaged with the first contacts. The first contacts are positioned and oriented to telescopingly engage the three second contacts during assembly, and at least one of the first and second contacts each include a mechanical retainer for securely retaining the first contacts in operable engagement with the second contacts after assembly. 
     These and other aspects, objects, and features of the present invention will be understood and appreciated by those skilled in the art upon studying the following specification, claims, and appended drawings. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS SHOWING PRIOR ART 
     FIG. 1 is a side view of a prior art shifter utilizing an interlocking device; and 
     FIG. 2 is an exploded perspective view of the prior art interlocking device of FIG.  1 . 
     BRIEF DESCRIPTION OF DRAWINGS SHOWING PRESENT INVENTION 
     FIG. 3 is an exploded perspective view of the present inventive interlock device according to the present invention; 
     FIG. 4 is a perspective view of the lead frame shown in FIG. 3; 
     FIG. 5 is a fragmentary perspective view showing the micro switch of FIG.  3  and one female connector of the lead frame of FIG. 4 for non-releasably engaging a male connector on the micro switch; 
     FIGS. 6 and 7 are top and perspective views of the female connector of the lead frame as shown in FIG. 5, with the female connector being supported in the housing of the interlock device of FIG. 3; 
     FIG. 8 is a plan view of the present interlock device of FIG. 3, with the top cover removed to better show internal components, the internal toggle mechanism being in an over-center interlocked position with the extendable pin extended; 
     FIG. 9 is a plan view similar to FIG. 8, but with the toggle mechanism being in a retracted position with the extendable pin retracted; 
     FIG. 10 is a perspective view of a continuous strip of lead frames; and 
     FIG. 11 is a flow diagram of a method of assembly for the interlock device of FIG.  3 . 
    
    
     DESCRIPTION OF A PRIOR ART SHIFTER 
     A prior art shifter  5  (FIG. 1) includes a base  6 , a shift lever  7  pivoted to the base  6 , and an interlock device  8  incorporating a toggle mechanism  9  (FIG.  2 ), a return spring  10 , an electromechanical device  11 , and a preassembled switch  12  all positioned in or attached to top and bottom housing components  13  and  14 . The electromechanical device  11  includes an electrical coil and an extendable pin  15 . A circuit board  16  includes conductors (not specifically shown) forming a branch circuit adapted for connection to a vehicle control circuit, and leads from the switch  12  and coil of the electromechanical device  11  are soldered to the conductors on the circuit board  16 . 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An interlock device  20  (FIG. 3) includes a housing  22  formed by opposing housing halves  46 ,  48 , a toggle interlock mechanism  24  including an extendable pin  26 , a preassembled micro switch  28 , an electromechanical device  30 , and a lead frame  32 . The lead frame  32  has a plurality of conductors  72 ,  74 ,  76 , and  78 , all operably attached to the bottom half  46  of the housing  22  between the opposing halves  46 ,  48 . When the extendable pin  26  is retracted (FIG.  9 ), the electromechanical device  30  operates the switch  28 . The lead frame conductors  72 ,  74 ,  76 ,  78  form a terminal that operably interconnects the switch  28  and the electromechanical device  30  to a vehicle control circuit (not shown) for operating the electromechanical device and for signaling the vehicle control circuit that the extendable pin has been retracted. The present arrangement, including the lead frame, permits an efficient automated assembly, and further does this using mechanical forming and assembly operations that are controllable and relatively low-cost. Thus, the present inventive concepts provide the advantages of reducing manufacturing and assembly costs while increasing the overall reliability and robustness of the interlock device. 
     The housing bottom half  46  (FIG. 3) is a molded polymeric component that includes integral molded-in protrusions  50  adapted to matingly engage “rosebud” apertures  106  formed on the lead frame  32 . A plurality of the protrusions  50  and apertures  106  are formed on the housing half  46  and in the conductors  70 ,  72 ,  74  and  76  of the lead frame  32 , and also various features are formed in the housing to trap and retain the lead frame conductors  70 ,  72 ,  74 ,  76 , so that each conductor is accurately located and retained in the housing  22 . This allows the lead frame  32  to be assembled as a unit by pressing the conductors  70 ,  72 ,  74 ,  76  downwardly, such that tines on the “rosebud” apertures flex and bite into the protrusions  50 . This results in a simple assembly that can be easily automated, such as by using a strip advance mechanism and downward pressing plunger. (See FIGS. 10-11.) 
     The electromechanical device  30  includes a coil (not specifically shown) and an extendable plunger  56 . Conductors extend from the coil for energizing the coil to extend the plunger  56 , the conductors terminate in two contacts  54  adapted to telescopingly mate with contacts  90 ,  92  on the lead frame, as discussed below. The plunger  56  is spring-loaded to be in a normally retracted position, and is operably interconnected to the driver  58  of the toggle interlock mechanism  24  by a magnet. 
     The toggle mechanism  24  includes a T-shaped arrangement of interconnected links. It is operably supported in the cavity of housing halves  46 ,  48  for movement between an overcenter interlock position (FIG. 8) and an unlocked retracted position (FIG.  9 ). 
     As noted above, the lead frame  32  includes four conductors or branches  70 ,  72 ,  74 ,  76  (FIG.  8 ). The first conductor  70  includes a male contact  80  and a female contact  82  (also called connectors  82 ,  86 ). The second conductor  72  further includes a male contact  84  and a female contact  86 . The third conductor  74  includes a male contact  88  and a female contact  90 . Finally, the fourth conductor  76  includes female contact ends  92  and  94 . The first, second, and third input male contact ends  80 ,  84 , and  88  are arranged and form a terminal shaped to receive a female plug of a wire harness from the main vehicle power train electrical system. The female contacts  82 ,  86 , and  94  are arranged to receive and electrically connect to the male connectors  96 ,  98 ,  100  extending from the switch  28 . Further, the female contacts  90  and  92  are configured and arranged to engage the contacts  54  that communicate electrical power to the electromechanical device  30 . Up tabs  102  and  104  are formed on the third and fourth conductors  74  and  76  respectively to engage opposite ends of diodes that extend between the third and fourth conductors  74  and  76 . A plurality of apertures  106  with angled retainer tines are formed along the four conductors  70 ,  72 ,  74 ,  76  to retain the branches accurately in place on housing protrusions  50 . 
     The female contacts  82 ,  86 ,  90 ,  92 ,  94  are formed to mechanically retain corresponding male connectors. This may be but is not limited to, for example, a spade type of connector or terminal. 
     The female contacts  82 ,  86 ,  90 ,  92  and  94  are similar to each other, such that only the contact  94  need be shown and described. The contact  94  (FIGS. 5-7) has a C-shaped cross section, and includes opposing sidewalls  120  with inwardly-formed downwardly-angled barbs  122 . The female contact  94 , including the barbs  122 , slidably engage and permit a telescoping engagement in a direction  101  by the male contact  96 , such that the switch  28  can be pressed into position and simultaneously electrically connected. However, the barbs  122  have a relatively sharp pointed tip that digs in and prevents removal of the male contact  96  from the female contact  94  once assembled. The housing bottom half  46  includes a C-shaped wall  124  that receives and supports the C-shaped female contact  94 , providing the support needed to prevent the C-shaped female contact from spreading apart. This maintains a pressure of the barbs  122  on the male contact  96 . This both provides an initial secure assembly, but also reduces warranty problems from connections coming loose and separating when in service. 
     A method of assembly (FIG. 11) for the interlock device  20  may be as follows. A lead frame  32  is stamped into the desired configuration out of a single piece of electrically conductive material. This lead frame may be produced in continuous form as shown in FIG.  10 . The lead frame  32  is then accurately positioned above the housing and then pressed mechanically down into housing  22  onto the housing protrusions  50 . Lead frame barbed apertures  106  non-releasably engage and accurately position the lead frame  32  to the housing  22 . The electromechanical device  30  is then positioned in housing  22 , including telescopingly engaging the male contacts  54  into female contacts  90  and  92 . Preassembled switch  28  with its associated switch contacts  96 ,  98 ,  100  is also pressed downward to telescopingly engage the male contacts  96 ,  98 ,  100  with the associated lead frame female contacts  82 ,  86 , and  94 . The four conductors  70 ,  72 ,  74 ,  76  are electrically separated by cutting the frangible tabs  60 , producing an operable interconnection between the lead frame  32 , electromechanical device  30 , switch  28 , and, when connected in a vehicle, to the vehicle control system (not shown). The toggle interlock mechanism  24  and retainer spring  44  are then positioned in housing  22 . Finally, housing cover  48  is installed over the lower housing half  46  and securely affixed thereto, such as by snap-attachment, screws, adhesive, sonic welding, or other means. 
     Interlock device  20  is shown in its natural state (FIG. 8) with the extendable pin  26  engaging a pocket in the shift lever ( 7 ) to prevent the pawl of the shift lever ( 7 ) from being moved, such that the shift lever ( 7 ) cannot be moved out of its park position. In operation (FIG.  9 ), if the vehicle circuit shows that predetermined vehicle conditions are met, it actuates the coil of device  30 , thereby electromechanically extending the plunger  56  of electromechanical device  30  outward, which causes the toggle mechanism  24  to be driven from an inline position (FIG. 8) to an off-centered position (FIG.  9 ). The toggle mechanism  24  as it is being driven off-center, acts to retract the extendable pin  26  from any abutment surface or cavity. The extendable pin  26  may be used to prevent relative movement of any parts. In the illustrated arrangement, it is used to lock a vehicle shifter in a park position on its base until the brake is depressed by preventing a pawl on the shifter from being moved out of a park position. Simultaneously when the pin  26  is retracted, the toggle mechanism depresses the switch  28 . Thus, the switch  28  can be used to input data to the vehicle&#39;s electrical control circuit. 
     It is contemplated that the present interlock device  20  could be used in other automotive or non-automotive applications. For example, it is contemplated that device  20  could be used on hotel door locks, and other locking arrangements using an extendable pin. Also, it is contemplated that the pin ( 26 ) of the interlock device ( 20  can engage an irregular surface having multiple locking locations, such that the lever or component being controlled could be held in any one of several different operative positions until predetermined conditions of the control circuit are met and the pin ( 26 ) is retracted. 
     It is to be understood that variations and modifications can be made on the aforementioned structure without departing from the concept of the present invention, and further it is understood that such concepts are intended to be covered by the following claims unless these claims by their language expressly state otherwise.