Abstract:
An electrical switch for use in an automotive vehicle includes a rotary carrier rotatable in response to engagement of a finger projecting from a movable main carrier. A detent structure is provided within a switch housing for engagement by a projection extending from the rotary carrier. The rotary carrier supports a conductive rotary contactor which is selectively actuable to conduct electrical current to a high beam headlamp conductive trace or a low beam headlamp conductive trace. The present invention provides a method for operating the electrical switch having a rotary mechanism. A channel is disposed between a plurality of conductive traces and the switch housing.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to electrical switches and specifically to an electrical switch having a rotary mechanism for use in an automotive vehicle. 
     Within the automotive industry, it is common to provide rocker type switches for selectively conducting electrical current from a positive current electrically conductive terminal to a variety of other conductive terminals feeding window lift motors, interior reading lamps, radios or the like. It is also known to provide rocker switches having an internally mounted and spring biased plunger for selectively depressing against one or more portions of a fulcrummed contactor. Examples of such conventional devices are disclosed within U.S. Pat. No. 5,293,507 entitled &#34;Movable Contact Piece Support Structure of a Seesaw Switch&#34; which issued to Hayakawa on Mar. 8, 1994, and U.S. Pat. No. 3,586,796 entitled &#34;Electrical Switch with Improved Common Terminal Housing Retaining Means for Pivoted Contact&#34; which issued to Simovits, Jr. on Jun. 22, 1971. 
     A traditional construction for a high beam/low beam headlamp dimmer switch is shown in U.S. Pat. No. 5,385,067 entitled &#34;Turn Signal Cancellation Mechanism&#34; which issued to Wiersing et al. on Jan. 31, 1995, which is assigned to the assignee of the present invention and is incorporated by reference herewithin. This patent discloses a driven end of a turn signal handle that engages within a slot of a carrier. A compression spring loaded contactor is mounted upon this carrier for electrical engagement between a plurality of conductive stamping. 
     It is also known to employ a foot actuated head lamp dimmer switch upon the floor boards of older vehicles. Depression of this large switch actuates a pair of plungers, each biased by approximately one-half inch diameter springs, for toggling a large pivoting contactor. In general, these foot actuated dimmer switches lack precision of movement, electrical reliability, low travel actuation and high effort actuation. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a preferred embodiment of an electrical switch for use in an automotive vehicle includes a rotary carrier rotatable in response to engagement of a finger projecting from a movable main carrier. In another aspect of the present invention, a detent structure is provided within a switch housing for engagement by a projection extending from the rotary carrier. In a further aspect of the present invention, the rotary carrier supports a conductive rotary contactor which is selectively actuable to conduct electrical current to a high beam headlamp conductive trace or a low beam headlamp conductive trace. Yet another aspect of the present invention provides a method for operating the electrical switch having a rotary mechanism. In still another aspect of the present invention, a channel is disposed between a plurality of conductive traces and the switch housing. 
     The present invention is advantageous over conventional designs since the electrical switch of the present invention provides a cock-and-fire mechanism for achieving low travel actuation of an electrical switch such as a high beam/low beam headlamp dimmer switch. Furthermore, the high beam/low beam switch of the present invention also feels crisp upon actuation. Another advantage of the present invention is that minimal forces are required to actuate the switch due to the part geometries and cock-and-fire mechanism. The rotary mechanism further causes less electrical errosion of the conductive traces as compared to traditional linear contactor movement which causes excessive friction and travel as well as electrical arcing. The electrical switch of the present invention also achieves a more reliable electrical contact. It is further noteworthy that the present invention can be easily preassembled without the traditional fear of the compression springs exploding components away from each other during assembly. Moreover, the channels provide a receptacle for undesired debris created within most switches during electrical arcing; this allows for a cleaner contact surface between the rotary contactor and the conductive traces. Additional advantages and features of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a turn signal cancellation mechanism within which the preferred embodiment of an electrical switch of the present invention is employed; 
     FIG. 2 is a cross sectional view, taken along line 2--2 of FIG. 1, showing a turn signal handle engaging a portion of the preferred embodiment electrical switch of the present invention; 
     FIG. 3 is a perspective view showing a portion of the preferred embodiment electrical switch of the present invention; 
     FIG. 4 is an exploded perspective view, taken opposite that of FIG. 3, showing the preferred embodiment electrical switch of the present invention; 
     FIG. 5 is a perspective view, taken opposite that of FIG. 3, showing the preferred embodiment electrical switch of the present invention; 
     FIG. 6 is an enlarged perspective view showing a finger employed in the preferred embodiment electrical switch of the present invention; 
     FIG. 7 is an enlarged top elevational view showing a spring and the finger employed in the preferred embodiment electrical switch of the present invention; 
     FIG. 8 is a fragmentary side elevational view showing an alternate embodiment finger and spring employed in the electrical switch of the present invention; 
     FIG. 9 is an enlarged perspective view, taken opposite that of FIG. 3, showing a rotary mechanism employed in the preferred embodiment electrical switch of the present invention; 
     FIG. 10 is a top elevational view showing a housing and conductive traces employed in the preferred embodiment electrical switch of the present invention; 
     FIG. 11 s an enlarged and fragmentary top elevational view showing the preferred embodiment electrical switch of the present invention; 
     FIG. 12 is a side elevational view, with a portion of the housing broken away therefrom, showing the preferred embodiment electrical switch of the present invention; 
     FIG. 13 is a diagrammatic side elevational view showing an interaction between movable contactors and the conductive traces employed in the preferred embodiment electrical switch of the present invention; 
     FIG. 14 is an electrical schematic diagram for the preferred embodiment electrical switch of the present invention; and 
     FIGS. 15-18 are cross sectional views, taken along line 15--15 of FIG. 11, showing a series of operational positions of the preferred embodiment electrical switch of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A turn signal cancellation mechanism for use in an automotive vehicle is shown in FIGS. 1 and 2. This device includes a housing 31 mounted to a vehicle steering column and a turn signal handle 33 having a driver accessible end 35. Handle 33 is pivotable about the arrows shown in FIG. 2 for operating a flash-to-pass headlamp feature and a high beam/low beam headlamp dimming switch feature. An actuator 37 is provided which contains a nominal detent position 39, a flash-to-pass detent position 41 and a high beam/low beam switching detent position 43. A spring biased plunger 45 within handle 33 engages with one of these detent positions. A driven end 47 of handle 33 is engagably received within a slot 49 within a main carrier 51. 
     Referring now to FIGS. 3-7, the preferred embodiment of an electrical switch 61 of the present invention includes a rotary mechanism 63, a plurality of conductive traces 65, a finger 67, and a linear contactor 69, as well as housing 31 and main carrier 51. Main carrier 51 has a centrally positioned interior chamber 71 for receiving a cap 73 of finger 67. A preloaded clock spring 75 upwardly biases cap 73 against receptacle 71 of main carrier 51. Finger 67 further has an elongated lever 77 with a tip 79, a pair of shoulders 81 and a head 83. Head 83 movably rests along an internal shell 85 of cap 73 while a compression spring biases shoulders 81 of lever 77 away from a lower surface of cap 73. Compression spring 87 and clock spring 75 act to center finger 67 in relation to main carrier 51. As will be discussed in greater detail hereinafter, the biased interaction between finger 67, a rotary carrier 101 and detent formations 307 and 309, defines the cock and fire mechanism. 
     Return flanges of linear contactor 69 are movably received within a leg 89 of main carrier 51. A compression spring 91 is also located between leg 89 of main carrier 51 and a depressed center of linear contactor 69 for biasing linear contactor 69 away from main carrier 51 and toward various of the plurality of conductive traces 65. Main carrier 51 further has four lateral flanges 93 for slidably engaging within a pair of facing tracks 95 integrally molded within housing 31. 
     Rotary mechanism 63 includes rotary carrier 101, a rotary contactor 103 and a projection or plunger 105. Rotary contactor 103 is secured to rotary carrier 101 for rotation therewith about a boss 107 integrally or separately attached to a segment 109 of housing 31. A pair of compression springs 111 serve to bias rotary contactor 103 away from rotary carrier 101 and toward various of the conductive traces 65. Rotary contactor 103 also has three raised contact points 113 extending from a nominal surface thereof. Plunger 105 is outwardly biased from within a groove 121 of rotary carrier 101 by a compression spring 123. 
     Segment 109 can be integrally molded as part of the remainder of housing 31 or may be separately applied to the remainder of housing 31 by sonic welding, heat staking, snap fitting or the like after rotary mechanism 63 and main carrier 51 have been preassembled thereto. Preassembly of these switching components to segment 109 achieves a modularized unit thereby promoting easy access and vision during assembly so as to reduce assembly cost and scrap while improving placement, accuracy and quality. 
     A supporting surface 151 of housing 31 has a pair of channels 153 integrally molded therein behind the plurality of conductive traces 65. This is illustrated in FIGS. 4 and 10-12. These channels 153 act to receive burned plastic, grease, metal oxides and other debris created during electrical arcing during switching and from the often dusty environment within which automotive vehicles are commonly used. These channels 153 aid in reducing debris build up between the contactors and conductive traces 65. Conductive traces 65 include a high beam headlamp stamping 181, a low beam headlamp stamping 183, a first positive current stamping 185 and a second positive current stamping 187. All of these stampings include substantially parallel electrical connector blades 189 for disengagably connecting to a wire harness electrical connector (not shown). Furthermore, all of these conductive traces 65 terminate in a contact section 191 disposed in a co-planar manner along surface 151 of housing 31. Unlike many traditional head lamp high beam/low beam switch constructions, such as that disclosed within the aforementioned U.S. Pat. No. 5,385,067, the conductive traces do not extend along a bottom surface 193 of the switch receiving cavity of housing 31. This provides for more efficient trace packaging and lower part costs. 
     Housing 31, rotary carrier 101, and main carrier 51 are all preferably injection molded from glass filled nylon such as DuPont Zytel® grade 70G30. Contactors 69 and 103 as well as conductive traces 67 are all preferably stamped from CA10194 copper. 
     An alternate embodiment of finger 267 is shown in FIG. 8. This finger embodiment employs a lever 277 integrally molded with cap 273. A leaf spring 287 has both ends captured within slots in a main carrier 251 and serves to center and retain finger 267 in relation to main carrier 251. 
     Referring to FIGS. 12-14, the high beam/low beam dimmer switch function 211 is achieved by rotation of rotary contactor 103 between high beam stamping 181 and low beam stamping 183. Rotary contactor 103 is always in electrical contact with first positive current stamping 185 which is electrically connected to a headlamp on/off switch 213. Meanwhile, a flash-to-pass switching function is achieved by linear movement of linear contactor 69 between second positive current stamping 187 and high beam headlamp stamping 181. A vehicle battery 215 is always feeding electrical current (B+) to second positive current stamping 187. 
     The operation of the cock and fire mechanism aspect of the present invention can best be observed in FIGS. 15-18. FIG. 15 illustrates main carrier 51 being moved toward rotary carrier 101 such that lever 77 has slid down a sloping surface 301, defined between a peak 303 and a first engagement surface 305 of rotary carrier 101. Rotary carrier 101 is shown disposed in a high beam rotated position such that plunger 105 engages a high beam detent formation 307. FIG. 16 illustrates lever 77 pushing, and thereby rotating, rotary carrier 101 as main carrier 51 continues to move toward rotary carrier 101. Finger 67 is in its fully cocked position. Referring now to FIG. 17, main carrier 51 is shown fully moved toward rotary carrier 101 such that lever 77 is fully pivoted, or has been fired, and rotary carrier 101 has been moved to a low beam rotated position. In this position, plunger 105 has engaged a low beam detent formation 309 within housing 31. FIG. 18 shows main carrier 51 moving away from rotary carrier 101 such that lever 77 is returned to its nominal central position. Returned linear movement of main carrier 51 toward rotary carrier 101 will subsequently engage lever 77 with an opposite engagement surface 311 for rotating rotary carrier 101 back to the rotated position shown in FIG. 15. Lever 77 does not need to engage rotary carrier 101 when only the flash-to-pass function is being operated. 
     While the preferred embodiment of this electrical switch has been disclosed, it will be appreciated that various modifications may be made without departing from the present invention. For example, the main carrier could pivot in relation to the housing as long as it serves to operate a rotary mechanism operable for switching between high beam and low beam modes. Furthermore, the disclosed cock and fire mechanism can be employed in a variety of other non-headlamp switches. Many other finger, contactor, carrier and conductive trace shapes and motions may be employed as long as the various aspects of the present invention are achieved. Various materials have been disclosed in an exemplary fashion, however, other materials may of course be employed. It is intended by the following claims to cover these and any other departures from the disclosed embodiments which fall within the true spirit of this invention.