Abstract:
A multifunction stalk switch combines a pivoting lever and an internal rod which can be independently rotated and slid in an axial direction to control multiple functions, including separate control of wiper on/off/intermittent settings, an intermittent delay setting, and a washer spray function. A robust design is achieved by avoiding the need for any wiring or circuit boards within the lever arm itself and locating all electrically conductive components in the base. Relief notches in the lever prevent sliding contacts from moving away from the circuit board when the lever arm is pushed in a direction perpendicular to the desired pivot plane.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates in general to a stalk-type lever switch for mounting to an automotive steering column, and, more specifically, to a stalk switch with provision for separately controlling wiper on/off/intermittent settings, an intermittent delay setting, and a washer spray function. 
     Stalk-type lever controls mounted to an automotive steering column for controlling windshield wiper and washer functions have become well accepted in the automotive industry. Various arrangements have been conceived for controlling multiple functions. These typically use various electrical switches and sliding contacts at the base and in the head of the stalk. Functions that may be controlled include wiper motor on continuous, wiper motor on intermittent, intermittent wiper delay setting, washer spray on, headlights and/or running lights on/off, high beam headlights on/off, turn signal lights on/off, etc. 
     In order to be successful, a stalk-type lever control should be robust, durable, and inexpensive to manufacture. To achieve the multiple control actions, however, the lever controls have become complicated. A lever often combines several different control action movements including axial rotation, circumferential rotation, and longitudinal displacement. Axial rotation may typically include either pivoting in a plane perpendicular to the axis of the steering column (as is sometimes used for controlling windshield wipers) or pivoting in a plane parallel with the axis of the steering column (as is sometimes used for controlling headlamp high beams). Circumferential rotation includes pivoting a ring around the longitudinal axis of the lever (as is used for controlling intermittent wiper delay). Longitudinal displacement may include a push button at the tip of the lever (as is sometimes used for controlling windshield washers). Combining these actions in a single structure has continued to be a challenge. 
     Robustness of a structure includes the ability to withstand forces applied in directions other than those being used for control actions. For example, a lever designed to pivot in only one plane (e.g., perpendicular to the axis of the steering column) must not malfunction if the lever is pushed in a direction outside that plane (e.g., in a direction parallel to the axis of the steering column). 
     SUMMARY OF THE INVENTION 
     The present invention provides an improved structure for a multifunction stalk-mounted switch having the advantages of robustness, durability, and ease of manufacture. 
     In one aspect, the multifunction switch apparatus comprises a lever including a lever arm having a distal end for manually manipulating the switch apparatus, a control frame at a proximal end of the lever, and a longitudinal bore. A case pivotally retains the control frame for movement in a pivot plane defined by a pivot axis. A circuit board is mounted in the case and comprises circuit traces on a surface thereof. A first contact is mounted to the control frame and slidably contacts the circuit traces. A rod is movably retained in the longitudinal bore and has a proximal end and a distal end. The rod includes a radial control arm and a drive surface at the proximal end. A contact carrier is rotatably mounted within the control frame and is coupled to the radial control arm so that the contact carrier rotates in response to axial rotation of the rod. A second contact is mounted to the contact carrier and slidably contacts the circuit traces. A plunger is biased in a first position and has a cam surface for receiving the drive surface and moves into a second position in response to longitudinal movement of the rod. The plunger includes an actuator surface. An on/off contact switch is mounted to the circuit board and makes selectable contact in response to the actuator surface. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front plan view of a multifunction switch according to the present invention. 
     FIG. 2 is a front exploded view of the switch. 
     FIG. 3 is a bottom exploded view of the switch. 
     FIG. 4 is a central cross section view of the switch. 
     FIG. 5 is a perspective view of a portion of the switch showing the contact carrier in one position. 
     FIG. 6 is similar to FIG. 5 showing the contact carrier moved into a second position by rotation of the rod. 
     FIG. 7 is a perspective view showing interaction of the rod and plunger. 
     FIG. 8 is a partial perspective view of the lever showing relief notches between the control frame and the lever arm. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to FIG. 1, a multifunction switch apparatus  10  includes a lever  11  and a housing  12 . In a preferred embodiment, switch apparatus  10  is shown as a wiper control stalk. Lever  11  is pivoted as indicated by arrows A for setting a wiper motor to settings of off, intermittent, low, or high as is indicated on switch apparatus  10  by wiper-function graphics  13 . An intermittent control ring  14  may be circumferentially rotated as shown by arrow B to control delay time when the wiper motor setting is set at intermittent. A washer push button or cap  15  can be depressed in the direction of arrow C to activate a washer motor that produces a washer spray. 
     Retainer clips  29  of housing  12  snap into a housing for a steering column (not shown). A collar  30  provides a bezel for interfacing switch apparatus  10  with the steering column. 
     Referring to FIG. 2, lever  11  includes a lever arm  16  and a control frame  17 . An integrally formed pivot post  18  extends above and below lever  11  and provides a pivot axis according to arrows A in FIG.  1 . Housing  12  includes a pivot hole  20  for receiving pivot post  18  and a cover plate  21  for attaching to housing  12  includes a pivot hole  22  for receiving the opposite end of pivot post  18 . Pivot post  18  provides the pivot axis for pivot movement of lever  11  in accordance with arrows A (FIG.  1 ). 
     A contact carrier  23  includes a sleeve  24  for fitting over pivot post  18  so that contact carrier  23  rotates in the interior of control frame  17 . A sliding contact  25  comprised of a conductive metal wiper is mounted to the bottom side of contact carrier  23 . A sliding contact  26  also comprised of a conductive metal wiper is mounted to the bottom side of control frame  17 . 
     A printed circuit board  27  containing conductive traces for implementing desired switch functions is retained in housing  12  between the bottom side of control frame  17  and cover plate  21 , so that sliding contacts  25  and  26  slidably engage the conductive traces. A plurality of connector pins  28  extend from circuit board  27  and through cover plate  21  for joining with a wiring harness (not shown) in the steering column. 
     Lever  11  contains a longitudinal bore  31  extending from the distal end of lever arm  16  to its proximal end to merge with the interior space of control frame  17 . A rod  32  is retained in bore  31  for longitudinal (or axial) and radial movement. Rod  32  has a distal end  33  and a proximal end  34 . A control arm  35  at proximal end  34  includes a ball  36  at its end which engages a socket  37  in contact carrier  23 . Ball  36  acts as a drive surface for pushing against socket  37 . Offset from distal end  33  is an alignment guide  38  which engages a bur  40 . Bur  40  is captured in intermittent control ring  14  so that rotation of ring  14  results in rotation of ball  36 . 
     A knobcase  41  is solidly connected to lever arm  16  in a manner that does not interfere with rotation of ring  14 . Washer push button  15  extends through knobcase  41  to received distal end  33  of rod  32 . A push surface inside washer push button  15  (not shown) abuts with distal end  33  when in its unactivated position such that the abutment does not interfere with rotation of rod  32 . 
     Proximal end  34  of rod  32  abuts with a plunger  42  which extends through circuit board  27 . Plunger  42  is biased into an upward position by a bias spring  43 . One end of a leaf contact  44  is attached to circuit board  27  by a rivet  45 . Leaf contact  44  is shaped so that the other end of leaf contact  44  is biased against a pair of contact rivets  46  on circuit board  27 . The bias of plunger  42  overcomes the bias of leaf contact  44  to break the connection, and the action of distal end  34  of rod  32  against plunger  42  causes contact of leaf contact  44  with contact rivets  46  as is discussed below with reference to FIG.  7 . 
     Contact frame  17  includes a detent holder  47  which captures a detent finger  48  and a detent spring  50 . A detent roller  51  is carried at the end of detent finger  48  to engage detent slots on the interior surface of housing  12  and to thereby establish detent positions for pivoting of lever  11  in the direction of arrows A (FIG. 1) to control wiper motor settings. 
     Lever arm  16  includes slots for receiving detent springs  52  and ball bearings  53  at diametrically opposite sides of lever arm  16 . Ball bearings  53  engage an interior race in ring  14  with recess points for providing detent positions for the rotation of ring  14  along arrows B (FIG. 1) to control intermittent delay time. 
     FIG. 3 is a bottom, partially exploded view of the switch apparatus showing the mounting of sliding contacts  25  and  26  to contact carrier  23  and control frame  17 , respectively. Cover plate  21  includes a plunger box  54  for receiving plunger  42  and a connector box  55  for receiving connector pins  28 . 
     The cross-sectional view of FIG. 4 shows a groove  56  in housing  12  for receiving a tongue  57  formed along the outside edge of control frame  17 . The tongue and groove are arranged to help guide the pivot motion of lever  11  in the desired pivot plane in conjunction with pivot post  18  and pivot holes  20  and  22 . 
     Referring to FIGS. 5 and 6, the action of ball  36  controlling rotation of contact carrier  23  within control frame  17  is illustrated. When rod  32  is rotated under manual control of ring  14 , ball  36  swings a corresponding arc. Since ball  36  is received in socket  37 , contact carrier  23  swings its own corresponding arc between respective detent positions of FIGS. 5 and 6. Consequently, sliding contact  25  moves to the respective circuit traces on circuit board  27  corresponding to the detent positions to obtain each respective intermittent wiper delay time or rate. Contact carrier  23  also moves whenever control frame  17  is pivoted under control of lever arm  16 . However, this motion is not important since sliding contact  25  is only used when control frame  17  is in the position corresponding to the wipers being set to intermittent. 
     Referring to FIG. 7, actuation of the on/off washer spray switch by longitudinal movement of rod  32  will be described in greater detail. Plunger  42  has a slanted cam surface  63  for slidably engaging a drive surface  64  at the proximal end of rod  32 . When plunger  42  is in its first position shown in FIG. 7, drive surface  64  has not yet acted on cam surface  63 . Plunger  42  has a disengagement arm  61  terminating in an actuator surface  62  which pushes up on leaf contact  44  to separate their contact ends from rivets  46 . 
     When washer push button  15  is pressed, rod  32  moves longitudinally (as shown by the dashed arrow) so that drive surface  64  pushes against cam surface  63  and plunger  42  moves to a second position (shown by dashed lines). Actuator surface  62  is retracted and leaf contact  44  follows its natural bias and moves into contact with rivets  46 . When washer push button  15  is released, plunger  42  moves back to the first position as a result of action by bias spring  43  thereby breaking contact between leaf contact  44  and rivets  46 . By providing a positive disengagement between leaf contact  44  and rivets  46 , any potential contact welding as a result of arcing is avoided. 
     Lever  11  is intended to pivot only in the pivot plane defined by pivot post  18 , pivot holes  20  and  22 , tongue  57 , and groove  56  (arrows A in FIG.  1 ). Nevertheless, it is possible that forces not aligned with the pivot plane would be applied to lever  11  such as indicated by arrows D in FIG.  8 . Components of such forces that are perpendicular to the pivot plane could tend to cause sliding contacts  25  and  26  to disengage the circuit traces on circuit board  27  due to the necessary clearances to permit rotation of lever  11  within housing  12 . Consequently, the present invention provides isolators  65  and  66  between control frame  17  and lever arm  16  in order to isolate control frame  17  from movement of lever arm  16  which is perpendicular to the pivot plane. Isolators  65  and  66  are substantially rigid with respect to forces applied in the pivot plane but are flexible with respect to forces applied perpendicular to the pivot plane. 
     In a preferred embodiment, isolators  65  and  66  are comprised of flexible joints  68  which are created by forming relief notches  67  in lever  11 . Flexible joints  68  can flex when lever arm  16  is moved in the direction shown by arrows D to allow contacts  25  and  26  to stay in sliding contact with circuit board  27 .