Abstract:
A clockspring assembly is provided having means to indicate that the clockspring assembly is properly centered upon installation in a motor vehicle. The clockspring assembly includes a hub and a rotor that is rotatable relative to the hub. A ribbon cable is wound about the rotor and provided with one end attached to the rotor and another end attached to the hub. An electronic centering indicator is mounted to the hub and is configured to indicate a centered position of the hub relative to the rotor as a result of a condition occurring when the hub becomes centered with the rotor. Upon the occurrence of the condition, the centering indicator is configured to provide an electronic signal indicating that the clockspring is properly centered.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. provisional application No. 62/104,270 filed on Jan. 16, 2015, which is herein incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present invention generally relates to clockspring assemblies. More specifically, the invention relates to an electronic centering indicator for a clockspring assembly. 
     2. Description of Related Art 
     Substantially all automotive vehicles are now manufactured with one or more airbags. Typically, a driver&#39;s side airbag is provided in the steering wheel facing the driver of the vehicle, and a second airbag is provided in the portion of the instrument panel facing the front passenger seat of the vehicle. The present discussion concerns the airbag located in the steering wheel. 
     Because the various collision sensors of an automotive vehicle provide a signal causing inflation of the airbag instantaneously with initiation of a collision event, and sometimes prior to the collision event, the airbag must be in continuous electrical connection with the collision sensors and other electronics in the vehicle body. Thus, a driver side airbag requires that an electrical connection be continuously provided between the airbag, as it rotates with the steering wheel, and the stationary sensors and other electronics. 
     Electrical connections between rotatable and stationary parts are known. In one well known connection, an electric brush rests upon a conductive ring, with one of the parts being rotatable. However, with this type of connection there is a risk, during the early or pre-stages of a collision, that the brush may separate or lose contact with the conductive ring. This loss of contact may create a transient failure in the electrical connection, resulting in delayed deployment of the airbag. 
     Another type of connection between rotatable and stationary parts is a clockspring assembly or connector. Clockspring assemblies typically include an outer housing, a rotor member and a “clockspring.” The clockspring is a coil of flat cable having one end connected to a plug or terminal on the outer housing and the other end connected to a plug or terminal on the rotor. The terminal on the outer housing, also referred to as the hub, is further connected to the electronics in the car body and the terminal on the rotor is connected to other electronics on the steering wheel associated with the airbag. As the steering wheel rotates, the clockspring of the clockspring assembly is wound and unwound, depending on the direction of rotation, and provides a continuous wired connection between the two parts. 
     Clockspring assemblies are typically manufactured at the site of a specialty manufacturer and then shipped to the vehicle manufacturer where they are further installed with the steering wheel. Because of this, it is important that the position of the outer hub with respect to the rotor member remain in a known position so that the clockspring assembly can be installed in a centered position on the steering wheel. Such a position is one where the clockspring is capable of an equal amount of rotation in either direction, without the clockspring becoming completely wrapped or unwrapped around the rotor. 
     In view of the above, it is apparent that there is a need for a mechanism that ensures that the clockspring assembly is properly centered once installed on the column of the steering wheel, before the vehicle leaves the assembly plant, removing the possibility of over rotation of the clockspring assembly due to misassembly. 
     SUMMARY 
     In satisfying the above need, as well as overcoming the enumerated drawbacks and other limitations, the present invention provides a clockspring that provides an indication that the hub and rotor are properly centered with respect to one another. 
     In one aspect the present invention provides an clockspring assembly having a rotor with an inner circumferential wall; a hub mounted to the rotor and being rotatable relative to the rotor; a ribbon cable wound about the hub and positioned within a chamber defined between the hub and rotor, the ribbon cable having a first end attached to the rotor and a second end attached to the hub; an electronic centering indicator mounted to the hub and configured to indicate a centered position of the hub relative to the rotor as a result of a condition occurring when the hub becomes properly centered with the rotor, the centering indicator being configured to provide an electrical signal upon detecting the existence of the condition and the signal indicating that the clockspring is properly centered. 
     In another aspect, the centering indicator is a sensor. 
     In a further aspect, the sensor is mounted in a circumferential wall of the hub and opposes the ribbon cable. 
     In an additional aspect of the invention, the sensor senses an indicium provided on the ribbon cable. 
     In still another aspect, the indicium is detected by the sensor via a noncontact method. 
     In yet a further aspect, the indicium is optically detected by the sensor. 
     In an additional aspect of the invention, the indicium is a region of color. 
     In yet another aspect, the indicium is detected by the sensor via a contact method. 
     In still a further aspect, the indicium is a raised projection on the surface of the ribbon cable. 
     In an additional aspect, the raised projection projects radially outward from the surface of the ribbon cable. 
     In another aspect, the sensor is a tact sensor configured to engage a raised projection as the indicium when the raised projection moves past the sensor during relative rotation of the hub and rotor. 
     In a further aspect of the invention, an aperture is formed in an outer circumferential wall of the hub and the indicator is a sensor being mounted in the aperture. 
     In an additional aspect, the indicator includes a gear assembly driven by rotation of the rotor. 
     In yet another aspect, the gear assembly includes a drive gear mounted for rotation with the rotor and a driven gear supported by the hub in a fixed location relative to the rotor. 
     In still further aspect of the invention, the drive gear is a ring gear fixedly mounted to the rotor. 
     In an additional aspect, the driven gear rotates a threaded portion coupled to a non-rotatable follower member, the follower member moving axially with rotation of the threaded portion by the driven gear. 
     In still another aspect, the follower member includes a threaded part correspondingly engaging the threaded portion rotated by the driven gear, the follower member further including at least one electrical contact. 
     In yet a further aspect, the indicator includes a switch configured to be engaged by the at least one electrical contact during axial movement of the follower member. 
     In an additional aspect, engagement of the switch by the at least one electrical contact closes the switch indicating proper centering of the hub relative to the rotor. 
     In another aspect of the invention, the rotor is mounted to a steering assembly of a motor vehicle and is rotatable with rotation of a steering column of the motor vehicle. 
     Further objects, features and advantages of this invention will become readily apparent to persons skilled in the art after a review of the following description, with reference to the drawings and claims that are appended to and form a part of this specification. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevational view of an clockspring assembly embodying the principles of the present invention installed on the column of a steering wheel assembly; 
         FIG. 2A  is a partial sectional view through the clockspring assembly seen in  FIG. 1 ; 
         FIG. 2B  is a partial sectional view through the clockspring assembly seen in  FIG. 1  according to a second embodiment; 
         FIG. 3A  is a side elevational view of a portion of a clockspring in accordance with the embodiment seen in  FIG. 2A ; 
         FIG. 3B  is a side elevational view of a portion of a clockspring in accordance with embodiment seen in  FIG. 2B ; 
         FIG. 4  is a perspective view of an clockspring assembly, not mounted to a steering wheel column, embodying the principles of the present invention in an additional embodiment; 
         FIG. 5  is perspective view of the clockspring seen in  FIG. 4  with the hub removed and illustrating the rotor and the mechanism for indicating if the clockspring assembly is centered; and 
         FIG. 6  is an enlarged view of the portion of the clockspring assembly encircled by line  6 - 6  in  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings, a clockspring assembly embodying the principles of the present invention is illustrated therein and generally designated at  10 . The clockspring assembly  10  is mounted on the column  12  of a steering wheel assembly, the steering wheel of which is not illustrated. As its primary components, and as more fully seen in  FIG. 2A , the clockspring assembly  10  includes four basic components: an outer housing or hub  14 , a rotor  16 , a ribbon cable  18  and a centering indicator mechanism  20 . Each of the hub  14  and rotor  16  and further includes terminals, respectively designated at  22  and  24 . The terminals  22 ,  24  electrically connect the clockspring assembly  10  to additional electronics and sensors of the vehicle, in the case of terminal  22 , or to the airbag (not shown) of the steering wheel assembly, in the case of terminal  24 . 
     In an actual implementation of a clockspring assembly  10  incorporating the principles of the present invention, the hub  14  and rotor  16  may take on a variety of shapes and configurations, but for the purposes of the present description the construction is illustrated in one of its most simple forms. 
     As seen in  FIG. 2A , the rotor  16  includes a circumferential wall  26  that is fixedly mounted to the steering column  12  such that it will rotate with rotation of the steering column  12 . This circumferential wall  26  defines the radially innermost wall of the clockspring assembly  10 . Extending radially outward from one end of the circumferential wall  26  is a radial flange  27 . The radial flanged  27  maybe integrally or unitarily formed with the circumferential wall  26 . The rotor  16  can be made of a variety of materials, including metal or plastic. 
     The hub  14 , like the rotor  16 , can be made of a variety of materials including metal or plastic. The hub  14 , as illustrated, includes a circumferential wall  32  from which extends a radial flange  34 . This circumferential wall  32  engages at one end the distal end of the radial flange  27  of the rotor  16 . Similarly, the distal end of the radial flange  34  of the hub  14  engages the circumferential wall  26  of the rotor  16 . These engagements are provided such that the hub  14  and the rotor  16  are rotatable with respect to one another. The engagements may therefore be provided in any manner that facilitates this purpose, and, in the illustrated embodiment, the engaged ends of the rotor  16  and the hub  14  are each provided with corresponding interlocking lips  35 ,  36 . 
     Additionally, the hub  14  is provided with multiple anchor points  38 , in the form of tabs projecting radially outward from the cylindrical wall  32 . The anchor points  38  preferably include apertures  40  through which fasteners (not shown) may be inserted to engage with other components of the vehicle. By engaging the anchor points  38  with other components of the vehicle, the hub  14  is stationarily fixed. 
     Together, the hub  14  and the rotor  16  defined a chamber  38  within which the ribbon cable  18  is received and wound about the rotor  14 . The ribbon cable  18  is a flat, cable having multiple conductors that run parallel to each other within a long thin strip of insulating material. For the purpose of clarity, the ribbon cable  18  is illustrated without delineating the individual components of the ribbon cable  18 . Additionally, a first, inner end of the ribbon cable  18  is electrically connected to the terminal  24  of the rotor  16  and a second, outer end of the ribbon cable  18  is electrically connected to the terminal  22  of the hub  14 . Since the hub  14  is stationary, as further discussed below, the inner end of the ribbon cable  18  will move about a central axis  26  of the steering column  12 . Rotation of the steering column  12 , and therefore the rotor  16 , is generally indicated by  30  and is depicted in  FIG. 2A . 
     As previously discussed, it is important that the position of the hub  14  with respect to the rotor  16  remain in a centered position, once assembled, prior to and during installation of the clockspring assembly  10  on the steering column  12 . In such a position, the clockspring assembly  10  will be capable of an equal amount of rotation, in either direction, without the ribbon cable  18  becoming completely wrapped or unwrapped around the rotor  16 . The centering indicator  20  is provided to ensure that upon installation the clockspring assembly  10  is centered. 
     As seen in  FIG. 2A , a first embodiment of the centering indicator  20  is provided. In this embodiment, a sensor  44  is mounted within a window or aperture  46  defined in the circumferential wall  32  of the hub  14 . Provided on the surface of the ribbon cable  18  is an indicium  48  that is detected by the sensor  44 . When the indicium  48  is detected by the sensor  44 , it is an indication that the hub  14  and rotor  16  are in the centered position of the clockspring assembly  10 . 
     Two alternatives are provided for this first embodiment of the centering indicator  20 . In the first alternative, as seen in  FIGS. 2A and 3A , the indicium  48  is of the nature that it may be optically or proximally detected by the sensor  44 . As such, the indicium  48  may be a section  50  of distinguishable color, reflective material or other optically or proximally perceivable material provided on the outer surface  52  of the ribbon cable  18 . In the illustrated instance, the section  50  is a region of distinguishable color and the sensor  44  is configured to optically detect the presence of the color or the change in color as the section  50  is beneath or passes beneath the sensor  44 . 
     In the second alternative, shown in  FIGS. 2B and 3B , the indicium  48  is a physical projection or bump  54  provided on the surface  52  of the ribbon cable  18 . In this instance, the sensor  44  is a tact or physical switch that, upon engagement of its contact member  56  with the projection or bump  54 , indicates that the hub  14  and rotor  16  of the clockspring assembly  10  are centered with respect to each other. 
     Referring now to  FIGS. 4, 5 and 6 , illustrated therein is a second embodiment of a clockspring assembly  10  incorporating the principles of the present invention. In this embodiment, the centering indicator  20  includes a gear assembly  58  utilized in conjunction with a contact switch  60  for determining if the clockspring assembly  10  is properly centered. 
     Turning to  FIG. 5 , to better illustrate the present embodiment of the centering indicator  20 , the clockspring assembly  10  is shown with the hub  14  and the ribbon cable  18  removed therefrom. 
     The gear assembly  58  includes a ring gear  62  that rotates with the rotor  16 . Since the ring gear  62  rotates with the rotor  16 , the ring gear  62  may be unitarily formed with the rotor  16  or may be integrally provided with the rotor  16  to rotate therewith. The ring gear  62  may be provided at various locations on the rotor  16 , but is preferably provided on one axial end of the rotor  16  so as to circumscribe the circumferential wall  26 . As shown, the ring gear  62  is located about the circumferential wall  26  opposite from the radial flanged  27 . 
     The ring gear  62  is engaged by a driven gear  64 . As the ring gear  62  rotates, the driven gear  64  also rotates. In order to reduce the overall size of the driven gear  64 , and idler gear (not shown) may be provided between the ring gear  62  and the driven gear  64 . Extending from a lower surface of the driven gear  64  is a central collar  66  that also rotates with the driven gear  64 . The central collar  66  is internally threaded and receives therein a correspondingly threaded portion  70  of a follower shaft  72 . The follower shaft  72  is joined with a follower block  74  that is received within a guide  76  that is non-rotatably coupled to the hub  14  or a portion of the vehicle. Rails  78 , formed on the follower block  74  slidingly ride within channels (not shown) formed within the guide  76  and aligned in the direction of the follower shaft  72  interaction between the and the channels thus prevent rotation of the follower block  74  within the guide  76 . Since the follower shaft  72  and follower block  74  are configured so as not to rotate, upon rotation of the driven gear  64 , the threaded portion  70  of the follower shaft  72  axially moves up or down, depending on the direction of rotation, within the caller  66 . This upward or downward movement in turn causes upward or downward movement of the follower block  74  relative to the guide  76 . 
     As seen in  FIG. 6 , extending off of the follower block  74  are a pair of electrical contacts  80 . The electrical contacts  80  correspondingly move with the follower block  74 . The contacts  80  are biased against the housing  81  of a lead block  82  within which a pair of electrical leads  84  is provided. The housing  81  includes a pair of apertures  86  through which the leads  84  are exposed. As the contacts  80  are moved along the lead block  82  the contacts  80  move into the apertures  86  and engage the leads  84 . When the contacts  80  engage the leads  84 , the circuit of the contact switch  60  is closed causing a signal to be sent from the clockspring assembly  10  to the vehicle indicating that the rotor  16  and hub  14  are centered properly. This happens only once, during initial assembly of the clockspring assembly  10  on the steering column  12 . Opposite from the driven gear  64 , the central shaft  66  is provided with a threaded end  68 . 
     As a person skilled in the art will readily appreciate, the above description is meant as an illustration of implementation of the principles this invention. This description is not intended to limit the scope or application of this invention in that the invention is susceptible to modification, variation and change, without departing from spirit of this invention, as defined in the following claims.