Patent Publication Number: US-6220778-B1

Title: Apparatus for retaining and aligning an electrical switch housing in a cast housing member

Description:
RELATED APPLICATIONS 
     This application is a continuation application of U.S. patent application Ser. No. 08/728,691 filed Oct. 10, 1996, U.S. Pat. No. 6,069,332, which is a continuation-in-part application of U.S. patent application Ser. No. 08/415,656 filed on Apr. 3, 1995, U. S. Pat. No. 5,596,180 for an Ignition Switch with Electrically Conductive Leaf Spring Members. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a mechanism for aligning and retaining a first member or housing that is slidably receivable within an aperture formed in a second member or housing, and more particularly, to a device for retaining and aligning an electrical ignition switch of a motor vehicle with a respect to a steering column housing or casting. 
     BACKGROUND OF THE INVENTION 
     It has been known in the past to attached first and second members, such as an electrical switch housing and steering column housing, with respect to one another using various types of threaded fasteners. While this type of attachment has provided adequate connection of the first and second members with respect to one another, it has not provided the desired ease of installation. In addition, this type of connection has not provided adequate, automatic compensation for differences in the tolerance of various assembled parts and proper alignment and interaction of those parts after installation of the switch housing with respect to the steering column housing. 
     SUMMARY OF THE INVENTION 
     The present invention seeks to address all of the deficiencies of the prior known fasteners for connecting a first member with a respect to a second member, and more particularly, to an electrical switch housing with respect to a steering column housing. An apparatus according to the present invention holds a first member with a respect to a second member, and more particularly retains and aligns an electrical ignition switch of a motor vehicle with a respect to a steering column housing. The apparatus can include a switch housing means having a first wall for supporting the electrical switch and at least one first aperture. The steering column housing is adapted for slidably receiving the switch housing means therein. The steering column housing has a second wall and at least one second aperture. Plunger means is engagable within the first aperture and moveable between a first position retracted within the first aperture and a second position extended outwardly with respect to the first aperture. The plunger means engages within the second aperture when the switch housing means is slidably engaged and fully seated within the steering column housing. The plunger means holds the switch housing means with respect to the steering column housing. Biasing means is provided for urging the plunger means toward the second position. 
     The present invention can also include guide means for guiding the switch housing means with respect to the steering column housing during insertion therein. The guide means can include the switch housing means having at least one guide rail disposed thereon, and the steering column housing having at least one complementary guide slot form therein for receiving the guide rail of the switch housing means during insertion of the switch housing means within the steering column housing. In the preferred embodiment, the first aperture is formed in the guide rail of the switch housing means for receiving the plunger means therein, and the second aperture is formed in a side wall defining the guide rail slot in the steering column housing. 
     Other objects, advantages and applications of the present invention will become apparent to those skilled in the art when the following description of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: 
     FIG. 1 is an exploded perspective view of an electrical ignition switch according to the present invention; 
     FIG. 2 is a simplified, exploded perspective view of a steering column housing or casting for slidably receiving an assembled electrical ignition switch housing according to the present invention; 
     FIG. 3 is a detailed, plan view of plunger means for retaining and aligning a switch housing of a motor vehicle with respect to a steering column housing according to present invention; 
     FIG. 4 is a side elevational view of the plunger means according to the present invention; 
     FIG. 5 is a detail cross sectional, side view of the plunger means according to the present invention engagable within a second aperture of the steering column housing; and 
     FIG. 6 is a cross sectional, detail view of the plunger means reciprocally received within a first aperture of the switch housing according the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention relates to a first member, such as an electrical ignition switch generally designated as numeral  10 , particularly for use as an ignition switch in vehicles for controlling the starter, ignition and accessory functions. Referring now to FIG.  1 , the electrical switch  10  according to the present invention includes a first cover  12 , or lower cover as illustrated in FIG. 1, to substantially enclose a first electrically conductive leaf spring means  14  with respect to a first part  16  of housing means  18 . Preferably, the leaf spring means  14  is constructed of electrically conductive, resiliently flexible material. A metallic material such as beryllium copper (BeCu) has been found suitable for switching 35 amps of continuous power up to peaks of approximately 50 amps, as well as low amperage applications down to the milli-amp range. The first leaf spring means  14  can include at least one electrically conductive leaf spring member  20 , and preferably a plurality of electrically conductive leaf spring members  20  independently operable and flexible with respect to one another, such as the three leaf spring members  20  illustrated as part of the first leaf spring means  14  in FIG.  1 . Each leaf spring member  20  includes an electrical contact  22  adjacent one end of the elongate leaf spring member  20 . The opposite end of the elongate leaf spring member  20  is fixedly secured in place, so that the cantilevered electrical contact  22  on each leaf spring member  20  can be flexed outwardly toward the first cover  12  while simultaneously resiliently biased by the resiliency of the leaf spring member  20  toward an original position of the leaf spring member  20 . Preferably, the first leaf spring means  14  is formed by injection molding plastic portions with respect to the electrically conductive leaf spring member  20 . A common support  24  is preferably molded at the one anchored end of each leaf spring member  20  for holding the one end of each leaf spring member  20  fixedly secured in a relative position with respect to one another and including apertures  26  for attachment to the housing means  18 . In addition, each leaf spring member  20  has at an opposite free cantilevered end an injection molded plastic pad  28  for operably receiving the driving force causing the leaf spring member  20  to flex outwardly from a normal position, generally in planar configuration, outwardly to a flexed position. As illustrated, each electrical contact  22  is in a closed position when in the normal unflexed position relative to the housing means  18  and is in an open position when flexed outwardly toward the first cover  12  away from the housing means  18 . Preferably, the first electrically conductive leaf spring means  14  as illustrated in FIG. 1 is a low current leaf spring means  14  capable of controlling the energization and deenergization of accessories and the like for the vehicle requiring current in the milli-amp range. The lower current leaf spring members  20  can be differentiated with respect to high current leaf spring member  118  by the reduced cross-section required for carrying the lower current. 
     The housing means  18  includes a first part  16  and a second part  30  which are separable from one another. The first part  16  of the housing means  18  includes a first wall  32  for supporting at least one electrical contact. The number of electrical contacts supported by the first wall  32  generally will correspond to the number of leaf spring members  20  existing for the particular application. By way of illustration, and not limitation, the present invention will be disclosed with reference to a plurality of electrical contacts. At least one electrically conductive member or plate is connected to each electrical contact. Preferably, the electrically conductive member is injection molded as an insert into the first part  16  of the housing means  18 . Adjacent each electrical contact, at least one aperture  38  extends through the first wall  32 , such that the aperture  38  opens opposite from the pad  28  formed on the outer cantilevered end of the elongated leaf spring member  20  corresponding to the electrical contact and corresponding aperture  38 . Plunger means  40  is provided extending through each aperture  38  extending from the pad  28 , or in contact with the pad  28 , for actuating the flexing movement of the cantilevered end supporting the electrical contact  22  corresponding to the electrical contact supported on the first wall  32  of the first part  16  of the housing means  18 . 
     As illustrated in FIG. 1, the plunger means  40  includes a plurality of separate, individually reciprocal actuator plungers  42  individually engaged within each aperture  38  formed in the first wall  32  of the housing means  18 . The first and second parts,  16  and  30  respectively, of the housing means  18  are engagable with one another to form a substantially enclosed chamber therebetween. Extending inwardly within the chamber from the first wall  32  is a pivot support  44 . A wave washer  46  is disposed on the pivot support  44  between the first wall  32  and rotatable means  48 . The rotatable means  48  is connected to the housing means  18  for at least limited angular rotating movement about a pivot axis extending generally normal to the first wall  32 . The rotatable means  48  includes a radially extending first side wall. The radially extending first side wall has at least one concentric cam surface extending arcuately along at least a sector of the rotatable means  48  and opposing the at least one aperture  38  in the first wall  32 . Preferably, a plurality of concentric cam surfaces can be provided corresponding in number to the number of apertures  38  and electrical contacts to be individually controlled by the electrical switch  10 . Each concentric cam surface can include a ramp portion extending between a lower, or longitudinally inward surface and an upper, or longitudinally outward surface, such that as the rotatable means  48  is rotated between angular positions, the plunger means  40  engages the corresponding inward surface, ramp portion and outward surface. While the plunger means  40  is engaging the pad  28  at one end and is opposite the inward surface at another end, the electrical contacts are closed with respect to one another creating an energized circuit, and after passing the ramp portion, with one end of the plunger means  40  engaging the pad  28  and the other end engaging the outer surface, the electrical connects are spaced from one another in an open position to deenergize an electrical circuit. By appropriately positioning the ramp portions between the inward surface and outward surface, various electrical circuits can be individually controlled independently of one another based on the angular position of the rotatable means  48 . 
     The rotatable means  48  preferably includes a generally cylindrical, disk-like member  60 . The disk  60  preferably has a plurality of gear teeth  62  formed along at least a portion of the periphery of the disk  60  for engagement with a corresponding gear member actuated by the key lock/ignition of the motor vehicle (not shown). Of course, other methods of actuating rotation of the disk member  60  can be provided. Along the other portion of the periphery of the disk  60 , a generally smooth longitudinally extending surface  64  is provided interrupted by a plurality of detents  66  for defining various angular positions of rotation for the rotatable means  48 . The plurality of detents  66  can correspond to an accessory detent, an ignition off or stop detent, a run detent and a start portion or detent. The smooth longitudinally extending surface  64  and detents  66  are engaged by a radially inwardly biased projection  76 . The projection  76  is preferably radially inwardly biased by a compression spring  78 . The projection  76  and spring  78  can be disposed within a radially outwardly extending aperture  80  formed in the housing means  18 . A torsion spring  82  is anchored to the housing means  18  at one end through an aperture formed in the first wall  32 , while the opposite end of the torsion spring  82  engages the rotatable means  48  to bias the rotatable means  48  in a desired rotational direction, preferably corresponding to movement of the rotatable means  48  from the start position to the run position when pressure is released from the ignition key of the motor vehicle. 
     The second part  30  of the housing means  18  is also illustrated in FIG.  1 . The second part  30  is similar to the construction of the first part  16  of the housing means  18 . The second part  30  preferably includes a second wall  94  for supporting at least one electrical contact  96 . Preferably, a plurality of electrical contacts  96  can be provided for individually controlling a plurality of electrical circuits. As illustrated in FIG. 1, the first part  16  is the low current side of the housing means  18 , while the second part  30  is the high current side of the housing means  18 . At least one electrically conductive member or plate  98  is connected to each electrical contact  96 . Preferably, the electrically conductive member  98  is injection molded as an insert into the second part  30  of the housing means  18 . At least one aperture  100  is formed through the second wall  94  adjacent to each electrical contact  96  for passage of plunger means  102  through the aperture  100 . The plunger means  102  may include elongate, individual actuator plungers  104  disposed within each individual aperture  100  for longitudinal reciprocation therethrough independently of one another. 
     The rotatable means  48  can include a radially extending second side wall opposing the second wall  94  of the second part  30  of the housing means  18 . Preferably, the second side wall can include at least one concentric cam surface. Preferably, a plurality of concentric cam surfaces are provided corresponding to the number of apertures in the second wall  94  of the second part  30 . Each cam surface includes a ramp portion extending between a lower or longitudinally inward surface and an upper, or longitudinally outward surface, such that the plunger means  102  slidably engages the second side wall of the rotatable means  48  and reciprocates in longitudinal direction in response to rotation of the rotatable means  48  as it engages the inward surface, ramp portion and outward surface. The opposite end of each elongate, actuator plunger  104  engages a cantilevered free end of a second electrically conductive leaf spring means  116 . The plunger means  102  is similar to the plunger means  40  and is engageable through the aperture  100  in the second wall  94  for slidably engaging the cam surface with a first end and for moving a second end corresponding to a contour of the cam surface as the cam surface moves with respect to the first end of the plunger means  102  when the rotatable means  48  is rotated between different angular positions. 
     Preferably, the second electrically conductive leaf spring means  116  includes at least one electrically conductive leaf spring member  118 . By way of illustration, and not limitation, the present invention is disclosed with respect to three individual, independently operable leaf spring members  118  for operably energizing and deenergizing high current electrical circuits capable of handling 35 amps of continuous current with peaks up to approximately 50 amps. Preferably, each leaf spring member  118  is formed of an electrically conductive material having resilient flexibility for urging or biasing the plunger means  102  toward it&#39;s respective cam surface. It has been found that a suitable electrically conductive metallic material for the leaf spring members  118  is beryllium copper (BeCu). Preferably, each leaf spring member  118  is insert molded with a common support  120  for fixedly securing one end of each leaf spring member  118  while leaving the opposite end of each leaf spring member  118  cantilevered for free flexing movement outwardly toward a second cover  122 . Preferably, each outer cantilevered end of the leaf spring member  118  is insert molded with an injection molded plastic pad  124  for engaging the opposite end of it&#39;s respective plunger means  102 . The common support  120  preferably includes apertures  126  aligned with apertures  26  through the common support  24  of the first leaf spring means  14  while passing through the first and second parts of the housing means  18  for assembling the electrical switch  10  in a final assembly with fasteners (not shown). 
     Locking means  86  is provided for releasably securing a first member, such as housing means  18 , with respect to a second member, such as an ignition switch steering column casting or housing  130 . The locking means  86  preferably includes reciprocal locking members  88  disposed on opposite sides of the housing means  18  within respective slots or first apertures  90  formed in the longitudinally extending side wall thereof. The locking members  88  are spring biased in a locking direction by compression springs  92 . The reciprocal locking members  88  are engagable within slots or second apertures  132  formed within the ignition switch casting  130  for the motor vehicle. Further details of the electrical switch according to present invention can be obtained from the pending U.S. Pat. No. 5,596,180 issued Jan. 21, 1997 entitled Ignition Switch With Electrically Conductive Leaf Spring Members, which is incorporated by reference herein in it&#39;s entirety. 
     Referring now to FIGS. 2-6, the steering column housing or ignition switch casting  130  slidably receives the switch housing means  18  therein. The switch housing means  18  supports the electrical switch and has at least one first aperture  90  formed therein. Locking means  86  is engagable within the first aperture  90  and is movable between a first position retracted within the first aperture  90 , and a second position extending outwardly with respect to the first aperture  90 . The locking means  86  engages within the second aperture  132  when the switch housing means  18  is slidably engaged and fully seated within the steering column housing  130 . The locking means  86  holds the switch housing means  18  with respect to the steering column housing  130  when in the fully seated position. Biasing means  134  is provided for urging the locking means  86  toward the second position. The biasing means  134  can include a compression spring  92 . Preferably, guide means  136  is provided for guiding the switch housing means  18  with respect to the steering column housing  130  during insertion therein. The guide means  136  can include the switch housing means  18  having at least one guide rail  138  disposed thereon. Preferably, the first aperture  90  is formed in the at least one guide rail  138 . The guide means  136  can also include the steering column housing  130  having at least one complementary guide slot  140  formed therein for receiving the guide rail  138  during insertion of the switch housing means  18  within the steering column housing  130 . Preferably, the second aperture  132  is formed in a side wall defining the at least one guide slot  140  in the steering column housing  130 . 
     Referring now to FIGS. 3-6, the locking means  86  preferably includes at least one reciprocal locking member  88  disposed within a first aperture  90  formed in the switch housing means  18 . Each reciprocal locking member  88  includes an aperture  142  formed therein for receiving a portion of the biasing means  134 . The aperture  142  may also include a closed end  144  defining a seat for one end of the compression spring  92 . In the preferred form, the reciprocal locking member  88  includes a first ramp surface  146  formed on an upper portion thereof extendible outwardly from the first aperture  90  of the switch housing means  18 . The first ramp surface  146  is disposed on the reciprocal locking member  88  for sliding engagement with the steering column housing  130 . Preferably, the first ramp surface  146  is disposed at an angle  148  with respect to a side wall  150  of the reciprocal locking member  88 . The angle  148  is preferably between 30° and 45° inclusive. The reciprocal locking member  88  can also include a second ramp surface  152  disposed at a second angle  154  with respect to a second side wall  156  of the reciprocal locking member  88 . Preferably, the second angle  154  is between 45° and 60° inclusive. 
     As best seen in FIG. 5, the steering column housing  130  can include an inclined surface  158  formed thereon. The inclined surface  158  may have at least one edge  160  engagable with the first ramp surface  146  of the locking means  86 . The one edge  160  of the inclined surface  158  is engagable with the first ramp surface  146  to hold the switch housing means  18  with respect to the steering column housing  130  when the switch housing means  18  is fully seated with respect to the steering column housing  130 . The inclined surface  158  preferably is disposed at an angle  162  with respect to a side wall  164  defining the second aperture  132  of the steering column housing  130 . The angle  162  is preferably between 45° and 60° inclusive. The second ramp surface  152  of the locking means  86  can define a leading surface during insertion of the switch housing mean  18  into the steering column housing  130 . In this configuration, the first ramp surface  146  of the locking means  86  defines a trailing surface during insertion of the switch housing mean  18  into the steering column  130 . The one edge  160  of the inclined surface  158  of the steering column housing  130  is engageable with the second ramp surface  152  during insertion of the switch housing means  18  slidably within the steering column housing  130 , until the switch housing means  18  is fully seated within the steering column housing  130 , such that the one edge  160  is engaged with the first ramp surface  146  to hold the switch housing means  18  in an aligned position with respect to the steering column housing  130 . As depicted in FIG. 5, the switch housing means  18  is engaged in a fully seated position with respect to the steering column housing  130 , so that the reciprocal locking member retains and aligns the switch housing means  18  with respect to the steering column housing  130  by engagement with edge  160 . 
     Referring now to FIGS. 3,  4  and  6 , the locking means  86  can include at least one, and preferably a plurality of ribs  166  extending outwardly along a longitudinal length of the reciprocal locking member  88 . A corresponding number of complementary grooves  168  can be formed in the side walls defining the first aperture  90  in the switch housing means  18 . The ribs  166  and complementary grooves  168  act in cooperation with one another to guide the reciprocal locking member  88  as it moves between the first and second positions. The locking means  86  is held within the first aperture  90  by the cooperating action between an end surface  170  formed on the reciprocal locking member  88  and a stop surface  172  formed as part of the housing  18  as best seen in FIG.  6 . 
     It has been determined through the performance of torque versus displacement and force testing that the required force to install the switch housing means  18  within the steering column housing  130  generally falls in the range of between approximately 7 Newtons and 10 Newtons inclusive. It has also been found through the performance of appropriate testing that the force needed to pull out the ignition switch housing means  18  from the fully seated position within the lock cylinder housing casting  130  is a maximum load generally in the range of approximately 300 Newtons to approximately 500 Newtons. An inspection after the tests found that the plastic holding tabs or locking members  88  on the ignition switch housing means  18  yielded at the maximum load. The test results listed above are given for purposes of illustration and by way of example, not by way of limitation. 
     While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.