Abstract:
A steering column control module comprises a housing having at least two receptacles. A printed circuit board is mounted in the housing, the printed circuit board carrying first and second electrical connectors. A third electrical connector is mounted in the housing remote from the printed circuit board. A ribbon cable is connected between the second and third electrical connectors. The receptacles are adapted to receive respective switch modules. The first and third electrical connectors are positioned and configures so that, when plugged into respective receptacles, the switch modules connect to respective ones of the first and third electrical connectors.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention is directed to an arrangement for connecting multi-switch modules to a steering column control module. 
       BACKGROUND 
       [0002]    A number of electromechanical systems are mounted on the steering wheel and steering column of typical, present day motor vehicle. A steering column control module (“SCCM”), positioned on the steering column just below the steering wheel, functions as a central nexus for the systems. Stalk lever switches are attached to the left and right sides of the SCCM. These, as well as steering-wheel mounted controls and systems (e.g. radio controls, cruise controls, horn switches, and air bags), are interconnected with other vehicular systems through the SCCM. The SCCM includes arrangements of circuit boards, wire cables, and multi-pin connectors for providing the necessary junctions between systems. U.S. Pat. Nos. 6,393,011, 7,595,457 and 7,819,427 show examples of such switches and control modules. 
         [0003]    The SCCM surrounds the steering column, and it can be challenging to design the SCCM to provide efficient and effective routing of electrical connections between the many components and subsystems in the steering column assembly. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention provides a steering column control module having an efficient and effective connecting arrangement between various circuit and system elements. 
         [0005]    In accordance with one example embodiment of the present invention, a steering column control module is described that includes a housing having at least two receptacles. A printed circuit board is mounted in the housing and has a first module connector and a ribbon connector mounted thereon. A second module connector is mounted in the housing at a location remote from the printed circuit board. A ribbon cable connects the ribbon connector and the second module connector. The first and second module connectors are positioned such that, when switch modules are inserted into respective receptacles, the switch modules connect to respective ones of the first and second module connectors. 
         [0006]    In accordance with a specific example embodiment of the present invention, a steering column control module is described that includes a housing adapted for mounting on a steering column of a motor vehicle, where the housing has at least two receptacles for receiving respective plug-in multi-switch modules. The two receptacles are disposed on opposite sides of said steering column when the housing is installed on a steering column. A printed circuit board is mounted in the housing. The printed circuit board carries electrical bus interface components for digital communication with downstream vehicle systems. The printed circuit board a plurality of electrical connectors mounted thereon including (a) a first module connector adapted to receive and mate with a matching electrical connector on a plug-in multi-switch module, (b) a ribbon connector adapted to receive one end of a ribbon cable, (c) an upstream connector adapted for connection with electrical components upstream from the module, and (d) a downstream connector adapted for connection with vehicle systems downstream from the module. A ribbon cable having first and second ends is included in the module. The second end is plugged into the ribbon connector on the printed circuit board. A second module connector is mounted in the module, remote from the printed circuit board. The second module connector is adapted to receive and mate with a matching connector on a plug-in multi-switch module. The first end of the ribbon cable is electrically joined to the second module connector. The first and second module connectors are mounted with respect to respective receptacles so that, when the multi-switch modules are plugged into the respective receptacles, each said first and second module connectors receives and mates with the matching connector of the respective multi-switch module. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The foregoing and other features and advantages of the present invention will become apparent to those skilled in the art to which the present invention pertains upon reading the following description with reference to the accompanying drawings, in which: 
           [0008]      FIG. 1  is a schematic representation of a steering column assembly, showing the location of the SCCM relative to other parts of the assembly; 
           [0009]      FIG. 2  is an exploded rear perspective view of the SCCM housing showing its printed circuit board and connectors; 
           [0010]      FIG. 3  is an exploded rear perspective view of the SCCM housing and cover; 
           [0011]      FIG. 4  is an exploded perspective view of a ribbon cable and a connector arrangement attached to one end thereof; 
           [0012]      FIG. 5  is a perspective view of the ribbon cable assembly and its relation to the printed circuit board; and, 
           [0013]      FIG. 6  is a functional block diagram of the SCCM showing its interconnections with other steering column and vehicular systems. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Referring to  FIG. 1 , a steering column assembly  10  for a motor vehicle is shown. The core of the assembly  10  is a steering column  12  having one axial end  14  to which a steering wheel  16  is attached and a second axial end  18  to which the vehicle&#39;s steering mechanism, e.g. a power rack &amp; pinion steering gear, not shown, is attached. The steering column  12  and steering wheel  16  are secured to rotate together about the axis of the steering column within a mounting structure  20 . The mounting structure  20  has a square cross section, is rigidly fixed to the frame of the vehicle (not shown), and passes through the firewall of the engine compartment (also not shown). The steering column is rotationally supported by bearings in the mounting structure  20 . 
         [0015]    A steering column control module (“SCCM”)  22  is affixed to the mounting structure  20 , and thus to the vehicle, and serves as a central interconnection nexus for many electrical systems that are mounted on the steering column assembly  10 . The SCCM has a housing including, for purposes of reference, a front surface  24 , a top surface  26 , and a right surface  28 , the remaining surfaces being hidden in the  FIG. 1  view. A rectangular hole is defined in the SCCM, running from the front to the back of the SCCM housing, and is sized and configured to receive the steering wheel mounting structure  20 . When the steering column assembly is being constructed, the SCCM  22  is slipped over and fastened to mounting structure  20  before the steering wheel  16  is installed on the end  14  of the steering column  12  via a conventional hub and spoke arrangement, not shown in detail. 
         [0016]    Right and left stalk switch modules  30  and  32  plug into the SCCM  22 . The stalk switch modules, which are of conventional design, include multiple electro-mechanical switches and are therefore, in a more generic sense, multi-switch modules. Each module includes one or more stalk or lever-actuated switches disposed in a switch block at the root of the stalk and one or more rotary switches operable with a knob mounted at the distal end of the stalk. Commonly, the right stalk switch module  30  is configured as windshield wiper controls and the left stalk switch module  32  is configured as headlamp controls. 
         [0017]    The housing of the SCCM  22  has associated side recesses defining receptacles for receiving the right and left stalk switch modules  30  and  32 . Only the receptacle  34  for the right stalk switch module  30  is visible in  FIG. 1 , but a similar side receptacle ( 58 , see  FIGS. 2 and 3 ) exists on the left side of the SCCM  22  for receiving the left stalk switch module  32 . Each receptacle has mounted in the bottom thereof an electrical module connector that mates with a matching connector on the bottom of the respective stalk switch module. These module connectors are not shown in  FIG. 1  but will be discussed in greater length below. 
         [0018]    A number of other electrical controls and elements are located in front of the SCCM (closer to the driver), generally in the area of the hub  36  of the steering wheel  16 . Such controls will sometimes be described herein as ‘upstream’ from SCCM  22 , meaning that they are further away, or more remote, from the vehicle wiring harness and the vehicle body control modules than is SCCM  22 . Among these controls and elements may be radio controls, cruise controls, a vehicle horn, and squibs or igniters of a single or multiple stage driver-side air bag. The hub-mounted controls and elements, which are not individually shown, are connected to other vehicle systems via the SCCM. An electrical cable running from the hub-mounted controls and elements plugs into an upstream connector  38  on the front face of the SCCM  22 . 
         [0019]    The controls and elements rotate with the steering wheel and steering column, however SCCM  22  and thus upstream connector  38  are fixed and do not rotate. To accommodate the rotation of the controls and elements, a so-called ‘clock-spring mechanism’ is mounted between the steering wheel hub  36  and the SCCM  22 . The clock-spring mechanism, which is conventional and is not shown, includes a wire cable wound around the steering column with sufficient slack so that the steering wheel can turn, for example, two and one half full turns, lock to lock, without imposing undue tension upon the cable. 
         [0020]    Referring to  FIGS. 2 and 3 , the housing  50  of the SCCM  22  has mounted therein a printed circuit board (“PCB”)  52 . PCB  52  is connected to, and receives electrical signals from, the connectors for the stalk switch modules  30  and  32  and the upstream connector  38 . PCB  52  combines the signals in various ways and forwards them to other vehicle systems via a downstream connector  54 . Downstream connector  54 , which is directly mounted on the rear of PCB  52  in such a position as to be accessible through a window in a rear cover  56  of SCCM  22 , will mate with a matching connector on the vehicle wiring harness. The vehicle wiring harness will distribute the signals to the vehicle body control module and other vehicle systems. Systems and components coupled to SCCM  22  via downstream connector  54  are considered ‘downstream’ from SCCM  22 . 
         [0021]    Electrical connectors must be mounted at several locations around the SCCM  22 , and notably adjacent side receptacles  34  and  58 . The side receptacles  34  and  58  are on opposite sides of the central mounting hole  60 . In previous known designs, a printed circuit board was provided that had an elongated profile designed to extend around the central mounting hole  60 . This profile from the known design was used so that the printed circuit board could carry connectors for both receptacles. This known printed circuit board design was relatively fragile and inconvenient to install. Further, the spacing between the two connectors in the known design was established by the rigid dimensions of the printed circuit board, hence the connector location relative to the respective receptacle was not independent for each receptacle. 
         [0022]    In the example embodiment being described of the present invention, a new approach is used for providing connectors adjacent each receptacle, where the arrangement is flexible and each connector is located independently of the other. 
         [0023]    The housing surfaces defining side receptacles  34  and  58  each have a corresponding back window  62 ,  64  for receiving an associated connector. PCB  52  is mounted directly over window  64 , its position established by a locating pin  66  molded into the housing  50  and by a screw fastener (not shown). A stalk switch module connector  68 , not visible in the drawings but identical to connector  74  to be described hereafter, is mounted directly to the PCB on its front face, in registration with the window. The pins of the module connector face the open end of the side receptacle  58  such that, upon installation of the left stalk switch module  32 , they mate with the pins of the complementary connector carried by the left stalk switch module  32 . 
         [0024]    A connector plate  70  is mounted directly over the other window  62  and, as with the PCB, the connector plate&#39;s position is established by a locating pin  72  and by a screw fastener (not shown). Connector plate  70 , which is perhaps best seen in the component drawings of  FIGS. 4 and 5 , serves as a support base for a stalk switch module connector  74 . As shown in  FIGS. 4 and 5 , stalk switch module connector  74  is physically and electrically attached to a flexible ribbon cable  76 . To provide a robust physical connection to the ribbon cable, connector  74  is provided with two metal solder feet  78 , one on either side thereof. The solder feet  78  include upright tabs that are press-fit into slots on either side of the connector. Module connector  74  further includes a series of pins  80  for solder connection to individual conductors on ribbon cable  76 . 
         [0025]    Ribbon cable  76  includes multiple parallel electrical conductors running along its length, embedded in and covered by a non-conductive plastic covering, and terminating at ribbon cable ends  82  and  84 . The first end  82  of the ribbon cable has a number of solder pads  86 , including two large pads for solder attachment to the feet  78  of connector  74  and an array for smaller solder attachments for the pins  80  of connector  74 . The large pads are not electrically connected to any of the ribbon cable conductors, but each of the smaller solder attachments of the array of solder pads is in fact an end of a corresponding one of the conductors of the ribbon cable  76 . Solder connections are formed between pins  80  and feet  78  on the one hand, and solder pads  86  on the other hand, by reflow soldering. The first end  82  of ribbon cable  76 , in turn, is fixed to connector plate  70  by a heat-activated adhesive. Alignment holes  88  in the ribbon cable  76  are used during the manufacturing process for precise alignment of end  82  of ribbon cable  76  with the connector  74 , on the one side, and connector plate  70 , on the other side. 
         [0026]    At the second end  84  of ribbon cable  76 , the insulating cover of the ribbon cable is stripped from one side of the cable to expose terminal ends  90  of the cable. The exposed terminal ends  90  are gold plated, and the end  84  is reinforced for stiffness by the addition of a small square of additional plastic  92  (see  FIG. 5 ) on the side opposite the exposed terminal ends  90 . 
         [0027]    As best seen in  FIG. 5 , PCB  52  has mounted thereon a zero-insertion-force ribbon connector  94  for receiving and securely holding the second end  84  of ribbon cable  76 , thereby providing electrical and mechanical connections with that end of the ribbon cable. Electrical continuity is thus established from the switches in the right stalk switch module  30 , through the mating connectors of the receptacle  34  (i.e., the unnumbered connector on the bottom of the right stalk switch module  30  and the connector  74  at the first end of the ribbon cable  76 ), through the ribbon cable  76 , through the zero-insertion-force ribbon connector  94 , and into the heart of PCB  52 . 
         [0028]    The length and geometry of the ribbon cable  76  is chosen to match the routing path of the cable in the SCCM housing  50 , and is deliberately made somewhat longer than the path length so that, when the connector plate  70  and PCB  52  are fixed in place over the receptacle windows  62  and  64 , some slack exists in the ribbon cable. The slack insures that the positioning of connector plate  70  and PCB  52  can be properly defined by their respective locator pins and fasteners. The ribbon cable  76  has an elongated slot  96  for receiving a pin  98  molded into the housing  50 . The pin is friction captured in the elongated slot, assisting in routing of the ribbon cable and in reducing vibration of the cable. 
         [0029]    Following installation of the components (including PCB  52 , ribbon cable  76 , and connector plate  70 ) into the housing  50 , the back  56  is temporarily snapped in place over the housing. The back  56  is then fixed more securely in place with four screws, not shown. The right and left stalk switch modules are pressed into the respective side receptacles  34  and  58  and each is fastened to housing  50  with two screws. The assembled SCCM is then ready for installation on the steering column of a motor vehicle. 
         [0030]    The connection between SCCM  22  and other parts of the steering wheel assembly is shown in block diagram form in  FIG. 6 . As shown in this figure, PCB  52  is equipped with four connectors. Module connector  68  provides electrical connection to left stalk switch module  32 . Ribbon connector  94  provides electrical connection to ribbon cable  76 , which in turn is connected to right stalk switch module  30  via module connector  74 . Upstream connector  38  provides electrical connection to a clockspring mechanism  100 , which in turn is connected to steering wheel controls and elements  102 , all located upstream of the SCCM  22 . Downstream connector  54  provides electrical connection to systems downstream of the SCCM  22  via the vehicle wiring harness, from which the signals are distributed to the vehicle body control module, safety control module, and other vehicle systems, indicated collectively at  104 . 
         [0031]    The role of PCB  52  in this arrangement is to provide the proper interconnection path between these various elements. Some electrical lines, such as the firing lines for the driver side air bag, are more or less routed directly through the PCB  52  from one connector to another without change. However, PCB  52  is populated with electronic components for conditioning and/or combining other signals from the various elements into a form suitable for communication to other, downstream vehicle system. In particular, PCB  52  will include digital bus interface components designed to interface the switches and other steering wheel hardware with standard vehicle serial communication busses, including for example LIN and CAN busses and one or more safety system busses. 
         [0032]    From the above description of the invention, those skilled in the art will perceive improvements, changes and modifications. Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims.