Abstract:
Exemplary embodiments of the present invention relate to a steering wheel arrangement for motor vehicles having a steering wheel, an airbag module held at the steering wheel and movable in the direction of the axis of the steering wheel, and an electrical contact system arranged between the steering wheel and the airbag module for the actuation of an electrical functional unit, in particular of a vehicle horn by a relative movement between the steering wheel and the air-bag module taking place in the direction of the steering wheel axis, where-in the contact system includes elongate extended electrical conductors which are attached to mutually confronting sides of the steering wheel and of the airbag module or only to the steering wheel or to the airbag module and extend in such a way that conductors spaced apart in the direction of the steering wheel axis cross at at least one contact position.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation-in-part of U.S. patent Ser. No. 11/085,817, filed Mar. 21, 2005, attorney docket number DP-313602, the contents of which are incorporated herein by reference thereto. 
     
    
     TECHNICAL FIELD  
       [0002]     The present invention relates to horn contact mechanisms and more particularly the present invention relates to an apparatus and method for providing a horn contact mechanism, which also provides a means for securing an airbag module to a vehicle component.  
       BACKGROUND  
       [0003]     Vehicles are supplied with driver side airbag modules; generally the driver side airbag module is located in the center of the steering wheel. This is also the same location where a horn-activating switch has traditionally been mounted. In addition, other inflatable cushions or airbag modules have been installed in vehicles.  
         [0004]     Various mounting mechanisms have been used for securing airbag modules to support structures in a vehicle. Non-limiting examples of such support structures include steering wheels and vehicle instrument panels. In one known mounting mechanism, mounting bolts are passed through openings in the vehicle support structures wherein a threaded portion of the mounting bolts engages a complimentary nut or threaded portion of the airbag module.  
         [0005]     Another mechanism for use with a driver side airbag module includes a means for providing a horn activation circuit wherein horn contact members are forced into contact in order to complete a horn activation circuit.  
         [0006]     In addition, increasingly higher demands are being made on electrical contacts, in particular horn contacts in steering wheel units for motor vehicles. This applies in particular for so-called floating horn systems in which the airbag module serves to actuate the vehicle horn and for this purpose is fixed to the steering wheel so that it is movable in the direction of the steering wheel axis—i.e. “floatingly”. The higher requirements relate in particular to the working life and the electrical operability of the contacts. Contact mechanisms electrically insulated from the steering wheel are increasingly demanded which, in the case of the horn systems which are of principal interest are also known under the catchword “isolated floating horn”. In such contact mechanisms, so-called open contacts can in particular to be used such as for example contact rivets or, with higher switching demands, encapsulated microswitches.  
         [0007]     In known steering wheel units an enormous degree of cost and complexity is sometimes used for the electrical insulation of the contacts, which considerably increases the manufacturing costs. Therefore, it is desirable to provide an apparatus and method for providing a horn contact mechanism that uses a minimal amount of components and is easy to install and manufacture.  
       SUMMARY  
       [0008]     Exemplary embodiments are directed to a method and apparatus for providing a horn switch assembly for securing an inflatable cushion to a steering wheel armature. In one embodiment, the horn switch assembly comprises: a backing plate defining a receiving area, the receiving area being configured to receive at least a portion of the inflatable cushion, the receiving area being defined by a peripheral wall of the backing plate; a plurality of mounting members depending outwardly and away from the peripheral wall, the plurality of mounting members providing a mounting surface, wherein the mounting surface of the plurality of mounting members is configured to receive a mounting mechanism therein, wherein each of the plurality of mounting members further comprises a contact point secured thereto; a non-conductive isolation mechanisms being configured to be secured to the steering wheel armature, wherein the isolation mechanism comprises at least one guide pin and at least one locking pin for guiding and movably securing the mounting mechanism thereto and the isolation mechanism comprises a portion of a wire having a non-insulated portion disposed proximate to the contact point of one of the plurality of mounting members; and a biasing member disposed between each of the mounting members and the isolation mechanism, wherein the backing plate is capable of movement between a first position and a second position, wherein the contact point of one of the plurality of mounting members makes contact with the non-insulated portion of the pair of wires in the second position providing a conductive path therebetween.  
         [0009]     In another exemplary embodiment, a horn switch assembly for securing an airbag module to a steering wheel armature is provided, the horn switch assembly comprising: a plurality of mounting mechanisms each being secured to the steering wheel armature, each mounting mechanism providing a means for securing the airbag module thereto; and a plurality of horn activation switches secured to the mounting mechanisms, each horn activation switch comprising: a housing; a plunger slidably received within the housing, the plunger having an airbag module contact end, a conductive horn circuit activation end, and an annular member disposed therebetweeen; and a biasing spring disposed about the plunger between the annular member and the conductive horn circuit activation end, wherein the biasing member makes contact with an inner flange of the housing; and a pair of wires each having a non-insulated portion disposed proximate the conductive horn circuit activation end, wherein the biasing member maintains the conductive horn circuit activation end in a facing spaced relationship with respect to the non-insulated portion of the pair of wires, and application of a force to the airbag module contact end causes the conductive horn circuit activation end to make contact with the non-insulated portion of the pair of wires and complete a horn activation circuit.  
         [0010]     In another exemplary embodiment, a backing plate for mounting an inflatable cushion to a vehicle is provided. The backing plate comprising: a receiving area configured to receive at least a portion of the inflatable cushion, the receiving area being defined by a peripheral wall of the backing plate; and a plurality of mounting members depending outwardly and away from the peripheral wall, the plurality of mounting members providing a mounting surface.  
         [0011]     Other exemplary embodiments are directed to a steering wheel arrangement for motor vehicles having a steering wheel, an airbag module held at the steering wheel and movable in the direction of the axis of the steering wheel, and an electrical contact system arranged between the steering wheel and the airbag module for the actuation of an electrical functional unit, in particular of a vehicle horn, by a relative movement between the steering wheel and the airbag module taking place in the direction of the steering wheel axis.  
         [0012]     The object of exemplary embodiment of the invention is to provide a steering wheel arrangement of the initially named kind which requires the smallest possible number of components in order to realize a reliable and permanently operable, and in particular low resistance contact system, and which makes the manufacture as simple as possible and as cost-favourable as possible, this should in particular also be possible for the integration of an “isolated floating horn” mechanism.  
         [0013]     Thus, in accordance with exemplary embodiments of the invention the contact system arranged between the steering wheel and the airbag module includes elongate electrical conductors which are attached to mutually oppositely disposed sides of the steering wheel and of the airbag module, or only to the steering wheel or to the airbag module, and which extend in such a way that conductors spaced apart in the direction of the steering wheel axis cross at at least one contact position. In this arrangement the conductors can each be electrically insulatedly mounted.  
         [0014]     The concept of the invention, of realizing a “switch” for the actuation of a functional unit, in particular of a vehicle horn simply by using crossing electrical conductors of elongate, extended shape, for example by correspondingly laid contact wires brings a plurality of advantages, without compromises having to be made when satisfying the initially discussed requirements, which is necessary, such as are placed on modern steering wheel units.  
         [0015]     Thus the elongate electrical conductors can already be integrated in a simple manner during the manufacture of the airbag module and of the steering wheel, or of the relevant components, whereby a considerable cost reduction can be achieved. Furthermore, the switch concept of the invention is characterized by an actuating feel or so-called “contactile feeling” which is perceived by the user as being particularly pleasant and which is, for example, to be preferred from the point of view of the user to that of known microswitches or so-called snap-disk contacts. The electrical function of the crossing conductors is at least equivalent with respect to contact resistance, working life and reliability to the known contact arrangements. This applies in particular, when, in accordance with a preferred embodiment, the crossing conductors have a round cross-section and in particular a circular cross-section. If required the electrical operability can be further improved by surface coating or special contact elements.  
         [0016]     Through the invention a contact mechanism can be realized in advantageous manner which is characterized by a low conducting resistance over the working life with a small current load in the range of a few thousandths of an ampere and which can be insulated relative to the steering wheel ground or to the vehicle ground or relative to other electrical systems. The high demands which are placed on a contact system with such a low current load in the range of a few thousandths of an ampere can be satisfied by the invention, since burning free or so-called “electrical fritting” of the contact surface is not possible.  
         [0017]     The invention furthermore makes it possible to achieve a small contact resistance at a plurality of distributed contact points of the electrical functional unit, in particular of a horn switch. The invention is based on the consideration that every contact surface has a foreign layer resistance which can be reduced by a cunning contact arrangement, with it being possible to destroy the foreign layer with power-free switching using comparatively high forces and a suitable geometry. Contacts between the contact pieces which come close to an ideal point contact yield particularly good results. In this connection the invention enables a self-cleaning of the contact positions without disturbing mechanical or electrical wear. Insulating foreign layers can be destroyed with the contact system of the invention with an adequately high contact force with plastic deformation of the contact pieces by mechanical microcracks or microfractures.  
         [0018]     The arrangement of the conductors arranged spaced apart in the direction of the steering wheel axis can take place in diverse manner and means. Thus, one conductor can be attached to the airbag module and one conductor to the steering wheel. In accordance with an exemplary embodiment, two crossing conductors can be jointly attached either to the airbag module or to the steering wheel. The attachment of the conductors can also take place at a so-called contact bridge associated with either the steering wheel or the airbag module, such as is frequently used in customary steering wheel arrangements. In all cases the relative movement between the airbag module and the steering wheel on actuation is exploited in order to allow the conductors to enter into electrical contact with one another at the at least one contact position.  
         [0019]     These considerations can be particularly favourably realized in practice with mutually crossing round conductors, i.e. with electrical conductors which have a round or circular cross-section.  
         [0020]     Advantageous further developments of the invention can be seen from the dependent claims, the description and also the drawing.  
         [0021]     An eventual requirement for electrical insulation of the contact system, in particular with respect to the vehicle ground or to the electrical systems can be particularly simply realized, in accordance with a preferred further development of the invention, in that the conductors are each attached to a component of the airbag module and/or of the steering wheel which is manufactured from an electrically insulating material, in particular of plastic.  
         [0022]     The contact system is preferably a component of a floating horn mechanism, such as was, for example, initially explained.  
         [0023]     The steering wheel or the airbag module can include a contact bridge and at least one conductor can be attached to the contact bridge. The contact bridge is in particular a component of a floating horn system: For the actuation of a vehicle horn the airbag module which is latched to the steering wheel or connected to it in some other way and means is pressed downwardly relative to the steering wheel in the direction of the steering wheel axis and thus—when the contact bridge is attached to the steering wheel—against the contact bridge, whereby a horn contact is actuated, i.e., in accordance with the invention, the crossing conductors are electrically contacted at the contact position.  
         [0024]     The contact bridge can alternatively also be attached to the airbag module. In the context of the present explanation of the invention the contact bridge can thus be seen, at least in the finally installed state, as a component of the steering wheel or of the airbag module, i.e. when there is talk of attachment of one or more conductors to the steering wheel or to the airbag module, then this also includes the possibility that the conductor or the conductors is or are attached to a contact bridge associated with the steering wheel and/or with the airbag module. The floating horn mechanism can be provided in accordance with the invention at the steering wheel or at the airbag module.  
         [0025]     The airbag module can include a carrier for a gas generator of the airbag module and at least one conductor can be attached to the generator carrier.  
         [0026]     A contact bridge and a gas generator carrier are preferably manufactured of plastic and the crossing conductors are attached on the one hand to the contact bridge and on the other hand to the generator carrier and thus electrically insulated relative to the steering wheel and the airbag module.  
         [0027]     At least one conductor is preferably disposed within a plane extending perpendicular to the steering wheel axis. At least one conductor can be provided in the form of a contact wire which preferably has a round and in particular circular cross-section.  
         [0028]     Furthermore, at least one conductor can have a surface which is achieved by a special surface treatment, in particular by an upgrade. Thus, by way of example, the conductor surface can be provided with a noble metal such as for example gold or silver or with a corresponding alloy.  
         [0029]     At least one conductor can be directly attached to the airbag module or to the steering wheel.  
         [0030]     Furthermore, provision can be made that at least one conductor is an integral component of the airbag module or of the steering wheel. For this purpose the conductor can be embedded into the material of the airbag module and/or of the steering wheel, and/or in each case of a corresponding component, by injection moulding plastic around it. The manufacture of the steering wheel unit in accordance with the invention can thus, in particular, be simplified and improved cost-wise in that plastic is already injection-moulded around the electrical conductors during or shortly after the manufacture of the airbag module and/or of the steering wheel and/or of the corresponding plastic components (in particular the gas generator and/or the contact bridges).  
         [0031]     Alternatively at least one conductor can be attached by a shape-locked and/or force-transmitting connection to the airbag module or to the steering wheel, in particular by a latch-connection or a clip connection. In this connection the relevant conductor can be directly latched or clipped to the airbag module and/or to the steering wheel. It is also possible that the airbag module and/or the steering wheel is provided with a plurality of individual holders to which the conductor is connected in shape-locked and/or force-transmitting manner. Such individual holders can be integral components of the airbag module and of the steering wheel.  
         [0032]     In order to improve the electrical operability and in particular the conduction resistance at least one conductor can be provided at a contact position with an additional contact section, in particular with a contact rivet. The contact section can also be connected to the conductor by a soldering, brazing or welding process. The contact section can in particular be a welded contact. The welded contacts or contact rivets are preferably specially surface-refined and indeed in a manner such as has already been discussed above.  
         [0033]     Through the matched contact geometries and special surface treatments particularly high working lives and particularly contact characteristics can be achieved in accordance with the invention. Electrical conductors in the form of contact wires which are executed as round wire or profiled wire are particularly advantageous as a result of their ideal shape. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0034]      FIG. 1  is a perspective view of an airbag module and a steering wheel configured to receive the airbag module;  
         [0035]      FIG. 2  is a perspective view of an airbag module;  
         [0036]      FIG. 3  is a top plan view of a base plate or backing plate constructed in accordance with an exemplary embodiment of the present invention;  
         [0037]      FIG. 4  is a perspective view of a base plate or backing plate constructed in accordance with an exemplary embodiment of the present invention;  
         [0038]      FIG. 5  is a perspective view of a base plate or backing plate constructed in accordance with an exemplary embodiment of the present invention secured to a steering wheel armature;  
         [0039]      FIGS. 6-8  are partial perspective views of a base plate or backing plate and isolation mechanism constructed in accordance with an exemplary embodiment of the present invention;  
         [0040]      FIGS. 9-11  are partial perspective views of a base plate or backing plate and isolation mechanism constructed in accordance with an alternative exemplary embodiment of the present invention;  
         [0041]      FIG. 12  is a perspective view of a base plate or backing plate constructed in accordance with an alternative exemplary embodiment of the present invention;  
         [0042]      FIG. 13  is a side view of a base plate or backing plate constructed in accordance with an alternative exemplary embodiment of the present invention;  
         [0043]      FIGS. 14A-24  are views of a mounting mechanism and horn activation switch constructed in accordance with alternative exemplary embodiments of the present invention;  
         [0044]      FIGS. 25-29  are views of a mounting mechanism and horn activation switch constructed in accordance with other alternative exemplary embodiments of the present invention;  
         [0045]      FIG. 30  is an illustration of principle of a part of a steering wheel arrangement in accordance with the invention with a closed horn contact;  
         [0046]      FIG. 31  is an illustration corresponding to  FIG. 30  with an open horn contact; and  
         [0047]      FIGS. 32-38  are further exemplary embodiments of the present invention in schematic representation. 
     
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0048]     Exemplary embodiments of the present invention are directed to an apparatus and method for providing a horn activation mechanism. In addition, exemplary embodiments are directed to horn activation mechanisms configured for use with and/or comprising a portion of the mechanism for attaching the driver side airbag module to the vehicle.  
         [0049]     This application is related to U.S. Pat. Nos. 5,380,037; 6,092,832; 6,196,573; 6,237,944; U.S. patent application Ser. No. 10/373,161, filed Feb. 24, 2003; U.S. patent Ser. No. 10/797,440 filed Mar. 10, 2004 and U.S. Provisional Patent Application No. 60/608,595, filed Sep. 4, 2004, the contents each of which are incorporated herein by reference thereto.  
         [0050]     In particular, exemplary embodiments of the present invention are directed to an airbag module connection assembly for use with “snap-in” driver side airbag modules and/or floating horns switches and exemplary embodiments are directed to apparatus and methods for limiting the number of components necessary to provide both a horn activation switch and a method or means for securing an airbag module to a steering wheel armature. An exemplary embodiment comprises a backing plate or base plate stamped from a piece of stock material such as steel wherein the backing plate defines a mounting area for a portion of the airbag module and a plurality of mounting members are configured to depend away from the mounting area, wherein the mounting members are configured for securement to the steering wheel.  
         [0051]     Referring now to  FIGS. 1 and 2 , a driver side airbag module  10  is illustrated. Driver side airbag module  10  is typically mounted to a hub or armature  11  of a steering wheel  12 . Typically, some form of mounting mechanism is provided to mount the airbag module to the steering wheel. As will be disclosed herein exemplary embodiments of the present invention are directed to mounting mechanisms for mounting the airbag module to the steering wheel as well as providing a horn activation circuit wherein the cost and complexity of the same is reduced. Generally, airbag modules include a base plate or backing plate  14  configured for receiving and engaging an inflatable cushion  16  and an inflator each of which is secured to the backing plate, which is then secured to the steering wheel. Although a driver side airbag module is illustrated, alternative exemplary embodiments of the present invention, without horn activation circuits are not intended to be limited to be used solely with driver side airbag modules. Other non-limiting uses include mounting mechanisms for side airbag modules, roof rail airbags and passenger airbags.  
         [0052]     Generally, and referring now to driver side airbag modules, the backing plate will include a central opening  18  configured for receiving a portion of the inflator therein. As is known in the related arts, the inflatable cushion is constructed out of a material configured for inflation upon receipt of an inflation gas from the inflator when certain predetermined vehicle conditions are sensed. The inflatable cushion is normally folded and covered by a plastic cover  20 , which preferably has an outer soft pad. As is known in the related arts the cover may be secured to the backing plate in any suitable manner, such as by cover tabs snapped over indented portions in the backing plate, as best shown in  FIG. 2 . In addition, the cover preferably includes tear lines or weakened portions that permit the cover to open during inflation of the inflatable cushion.  
         [0053]     Referring now to  FIGS. 3-8 , exemplary embodiments of the present invention are illustrated.  FIGS. 3 and 4  illustrate backing plate  14  wherein the backing plate is configured to define a receiving area  22  for receiving a portion of component parts of the airbag module (e.g., inflator, inflatable cushion, retainer ring, etc.) and a plurality of mounting flanges  24 , which depend away from a periphery  26  of the receiving area. In accordance with an exemplary embodiment three mounting flanges depend away from periphery  26 , two at either side of the receiving area and one located between the other two. This configuration provides stability to the mounting of the airbag module to the armature as it moves between horn activating and non-horn activating positions. Of course, it is understood that any number of mounting flanges are contemplated to be within the scope of the present invention. As will be discussed herein mounting flange or mounting member  24  provides a surface area for mounting the airbag module to the steering wheel. In addition, the mounting flanges are provided with apertures for facilitating the securement of the base plate to the steering wheel armature.  
         [0054]     Referring now to  FIGS. 5-8  and in accordance with one exemplary embodiment, the securement of backing plate  14  to the steering wheel armature is illustrated. In accordance with an exemplary embodiment the backing plate is movably secured to the steering wheel armature wherein an applied force to the airbag module will cause the backing plate to move from a facing spaced relationship towards the steering wheel armature. In addition,  FIGS. 5-8  also illustrate the features of the horn activation mechanism or switch. As illustrated, each mounting flange has a contact point  28  secured thereto. In accordance with an exemplary embodiment contact point  28  comprises an electrically conductive material which will close or complete a circuit of a horn activation mechanism when the backing plate is moved toward the armature from a first position to a second position, wherein the contact point will complete the horn activation circuit and activate the horn. A non-limiting example of an embodiment of contact point  28  is a copper rivet. In addition, and in this embodiment backing plate  14  is also formed out of a conductive material, which is provided with an electrical current thus contact point  28  is provided with a current or a conductive path to complete a circuit or close a horn activation switch when contact point  28  makes contact with another portion of the horn activation circuit. A non-limiting example of the conductive material for backing plate  14  is steel.  
         [0055]     As illustrated in  FIGS. 5-8 , a non-conductive isolation mounting mechanism  30  is secured to the armature. The non-conductive isolation mounting mechanism comprises guide pins  34  and locking pins  36  integrally molded therein. The locking pins are configured to engage a locking pin proximate to an opening in a mounting feature or mounting mechanism  38 , which is secured to the mounting flanges by snapping or securing the same into at least one opening in at least one mounting flange. In an exemplary embodiment, mounting mechanism  38  and isolation mounting mechanism  30  comprise a non-conductive material, such as plastic, which is easily molded into the configurations illustrated in the attached figures. Also, and as illustrated mounting mechanism  38  and non-conductive isolation mounting mechanism  30  each comprise a single unitary structure having a “U” shaped configuration. Of course, other configurations are contemplated to be within the scope of the present invention. Thus, mounting features or mounting mechanism  38  and non-conductive isolation mounting mechanisms  30  provide a non-conductive securement between steering wheel armature  11  and base plate  14 . In order to secure locking pins  36  to the backing plate locking spring members  39  are secured to the mounting feature via bolts or rivet  41 , wherein locking spring member  39  is positioned to engage an opening or slot in the locking pin. The locking springs are positioned and configured to be biased into a locking configuration wherein the airbag module is prevented from being completely removed from the steering wheel armature unless the locking spring is urged into a non-locking position by a tool such as a screwdriver blade wherein the locking spring is no longer engaged in the opening of the locking pin, thereby allowing removal of the airbag module from the steering wheel armature. In addition, rivets, bolts or fastener  41  may be used to secure mounting mechanism  30  to the mounting members  24 .  
         [0056]     In addition, the insulator is also configured to have an opening or slots  43  in a sidewall to allow for biasing of the locking spring into the non-engagement position. Accordingly, the locking pins are configured to engage a portion of the locking spring, which provides a means for securing the airbag module to the steering wheel armature.  
         [0057]     Locking pins  36  comprises an opening (illustrated in  FIG. 12  as item  62 ) for engaging the spring member disposed proximate to an opening in feature  38 . The opening of the locking pin is configured to have a height or width large enough to allow movement of the backing plate to and from the armature while preventing disengagement of the locking pin from the opening in the mounting feature.  
         [0058]     In addition, guide pins  36  are configured to have a partial frustoconical shape for slidably engaging openings  44  of mounting feature  38 . Disposed about the guide pins and between the mounting members are biasing springs  46 . The biasing springs are under compression after locking pin  36  engages the locking member disposed proximate to the opening in the mounting feature. Thus, biasing springs  46  provide a biasing force for maintaining the backing plate in a facing spaced relationship with the steering wheel armature.  
         [0059]     Thus, and as a force is applied to the airbag module generally in the direction of arrow  47 , the mounting flanges are able to move towards the non-conductive isolation mechanisms wherein contact point  28  is able to contact a wire  48  disposed in a wire mounting feature  50  of non-conductive isolation mounting mechanism  30 . As illustrated in  FIG. 6 , a single wire may be positioned to have non-insulated portions located proximate to the backing plate. Once the contact point touches the wire a circuit of the horn activation system is completed and the horn is activated. In other words, contact point  28  comprises an electrically conductive material allowing a current to flow from the wire through the electrically conductive member of the backing plate, which is either connected to a ground or a power supply via another wire thus, completing a circuit wherein the completion of the circuit will cause the horn sound. Once the force is removed the biasing force of the biasing spring will return the backing plate and mounting members in a facing spaced relationship wherein the contact point will no longer complete the horn activation circuit. It is also noted in this embodiment that the armature is also configured to allow for the movement of the backing plate to and from the armature.  
         [0060]     As illustrated in  FIGS. 3-8 , portions of the mounting mechanism are formed and located on the backing plate while complementary features are secured to the armature in order to provide a mounting mechanism and a horn switch, wherein the complexity and number of components are reduced thus providing a more efficient means for securing the airbag module to the armature while also providing a horn activation circuit. In addition, the lead to the non-conductive isolation mounting mechanism is isolated from the armature by the non-conductive material of the mounting mechanism thereby preventing the same from inadvertently completing the horn activation circuit. Moreover, the configuration of the mounting member and the horn activation switch allows the number of parts to be reduced thus decreasing the costs and complexity associated with the mounting mechanism and horn activation switch.  
         [0061]     Referring now to  FIG. 8 , a middle mount portion  32  of the non-conductive isolation mounting mechanism is illustrated. Here a snap in pin  52  is configured to engage a locking pin  39  disposed proximate to an opening  54  in a mounting feature  56  of mounting mechanism  30 , which is mounted to mounting member  24 . Snap in pin  52  is configured to provide both features of locking pin  36  and guide pin  34 , wherein a biasing spring  58  is disposed about snap in pin  52 . Again, a wire  48  is disposed in a wire-mounting feature  50 , wherein the horn activation circuit is completed as contact portion  28  makes contact with any one of the un-insulated portion of the wire located proximate to the contact point  28 . In accordance with an exemplary embodiment, it is noted that the horn activation circuit is configured to activate the horn once one of the contact portions makes contact with an un-insulated portion of the wire. A non-limiting location of the middle mount non-conductive isolation mounting mechanism is at a six o&#39;clock position on the steering wheel.  
         [0062]     In an alternative exemplary embodiment a pair of non-conductive isolation mounting mechanisms  30  and a middle mount non-conductive isolation mounting mechanism  32  are each separately secured to the armature. Referring to the pair of non-conductive isolation mounting mechanisms  30 , each non-conductive isolation mounting mechanism comprises a guide pin  34  and a locking pin  36  integrally molded therein. Locking pin  36  is configured to engage a locking member proximate to an opening in a separate mounting feature or mounting mechanism  38 , which is secured to each mounting flange by snapping into at least one opening in the mounting flange. In an exemplary embodiment, mounting mechanism  38  comprises a non-conductive material, such as plastic. Thus, mounting features or mounting mechanisms  38  and non-conductive isolation mounting mechanisms  30  and  32  provide a non-conductive securement between steering wheel armature  11  and base plate  14 . Accordingly, and in this embodiment three separate non-conductive isolation mounting mechanisms and three mounting mechanisms  38  are provided to secure locking pins to the backing plate, wherein the middle mount non-conductive isolation mounting mechanism has a snap in pin configured to provide both features of the locking pin and the guide pin  34 . Again, a wire  48  is disposed in wire-mounting features  50 , wherein the horn activation circuit is completed as contact portion  28  makes contact with any one of the un-insulated portions of the wire located proximate to the contact point  28 . In accordance with an exemplary embodiment, it is noted that the horn activation circuit is configured to activate the horn once one of the contact portions makes contact with an un-insulated portion of the wire.  
         [0063]     Referring now to  FIGS. 9-13  an alternative exemplary embodiment of the present invention is illustrated. Here backing plate  14  is configured to have the locking pins stamped from the material comprising mounting flanges or mounting portions  24  and separate non-conductive isolation mounting mechanisms  30  and  32  are configured to have an opening  60  with a locking member  39  for engaging an engagement opening  62  of the locking pins. In addition, mounting mechanisms  38  may also be disposed on the mounting flanges to slidably receive the guide pins. In this embodiment, the locking pins are stamped from the stock material used for backing plate  14  at the same time the backing plate  14  is formed by a stamping process. Accordingly, the die or tool used during the manufacturing process of backing plate  14  is configured to both define backing plate  14  as well as the locking pins. In this embodiment operation of the horn activation switch or circuit is similar to the previous embodiments wherein the backing plate is applied with a current via wire and the circuit is complete or the switch is closed when the contact point makes contact with the non-insulated portion of wire  48 .  
         [0064]     Referring now to  FIGS. 14A-22 , other alternative exemplary embodiments of the present invention are illustrated. Here, a horn activation switch  64  is mounted proximate to a mounting mechanism  68 . Switch  64  is secured to mounting mechanism  68  by a reinforcement plate  70 . A non-limiting example of the material contemplated for reinforcement plate  70  is steel. Switch  64  comprises a housing  72  configured to slidably receive a plunger  74  therein. Plunger  74  is configured to have an airbag module contact portion  76 , a horn switch contact portion  78  and an annular member  80  disposed therebetweeen. Annular member  80  and plunger  74  are configured to locate a biasing member  82  between annular member  80  and a bottom portion  84  of housing  72 . Accordingly, plunger  74  is capable of movement between a non-horn activation position to a horn activation position wherein biasing member  82  is compressed. Therefore, once an actuating force is removed the biasing spring will move the airbag module and contact portion  76  away from a horn activating position.  
         [0065]     In one embodiment, and as illustrated in  FIGS. 14A and 14B , a portion  84  of mounting mechanism  68  is configured to have a shoulder portion  86  configured for engaging a mounting member of a backing plate of an airbag module. In addition, portion  84  is configured to extend past the steering wheel armature as well as provide a channel or receiving area  90 . Channel  90  is configured to allow a tool such as a screwdriver to be inserted therein to pry the mounting member away from shoulder portion  86  thereby allowing airbag module to be disengaged from the mounting mechanism. Alternatively, mounting mechanism  68  can be configured to include a feature that is engaged by a locking member and aperture disposed on the backing plate.  
         [0066]     Referring now to  FIG. 15 , an alternative arrangement of the mounting mechanism of  FIGS. 14A and 14B  is illustrated. Here a plurality of horn activation switches are configured for use with a plurality of horn mounting mechanisms  68 . As illustrated in  FIG. 15  horn activation switches are configured to be secured to a single mounting mechanism wherein the other two horn activation switches are secured to separate mounting mechanisms. In this embodiment, a pair of conduits  96  are provided. Each conduit  96  provides a passage for a pair of wires  48 , wherein an un-insulated portion of the pair of wires is disposed within the lower portion of the housing such that contact portions  78  of plungers  74  complete the horn activation circuit.  
         [0067]      FIG. 16  illustrates yet another exemplary embodiment wherein the mounting mechanism and horn activation switch of the  FIG. 15  embodiment is associated with a mass damper  100  movably secured to the steering wheel armature. Mass damper  100  will be secured to the steering wheel via a biasing member tuned to a specific frequency in order to cancel out unwanted vibrations in the steering wheel. In addition, some of the mounting members are configured to have guide portions  69  with guide openings  71  associated thereto. Openings  71  are configured to receive and engage datum locators  73  of a flange or a base plate  75  of an inflator  77 . Accordingly, the openings of the guide portions are configured to limit the X and Y movement of the inflator as taught by U.S. patent application Ser. No. 10/373,161, filed Feb. 24, 2003, the contents of which are incorporated herein by reference thereto.  
         [0068]      FIG. 17  illustrates the pair of wires and their un-insulated portions as viewed from the bottom of the housing of the horn activation switch. As illustrated, contact point  78  is configured to make contact with each of the un-insulated portions of the pair of wires so as to complete the horn activation circuit as the airbag module is depressed towards the steering wheel armature and the plungers are depressed and the contact point allows a horn activation circuit to be completed.  
         [0069]      FIG. 18  is a top perspective view of housing  64  wherein an inner opening  102  is illustrated. Inner opening  102  is configured to receive plunger  74  therein. Opening  102  comprises a flange portion  104  defining an inner opening  106 . Inner opening  106  is configured to allow a lower contact portion of the plunger to be slidably received therein. Flange portion  104  provides a surface for contacting with the biasing member or spring  82  configured to be disposed about to the lower portion of the plunger between annular portion  80  wherein spring  82  provides a biasing forced to plunger  74  via annular portion  80  and flange portion  104 . In addition, flange portion  104  prevents the biasing member or spring from making contact with the un-insulated portions of the wires disposed in housing  64  thus preventing inadvertent activation of the horn circuit. In the illustrated embodiment, and as shown in  FIGS. 15-18 , the mounting plate  70  provides a means for retaining plunger  74  in opening  102  as well as comprising an opening  110  configured to allow a portion of plunger  74  to slide therethrough thus making contact with the backing plate of the airbag module.  
         [0070]      FIG. 19  illustrates a bottom view of housing  64  wherein conduit openings  112  are defined partially by housing  64  and a lower housing mounting member  114 . Lower housing mounting member  114  is configured to have a pair of features  116  configured to be received within openings defined by a complementary pair of features  118  of housing  64 . Accordingly, and when lower housing mounting member  114  is secured to housing  64 , a pair of openings is provided for insertion of wires therein. As illustrated in  FIG. 17 , an un-insulated portion of the wires is received in the lower portion of the housing, wherein the contact point of the plunger is able to make contact and complete the horn activation circuit.  
         [0071]      FIG. 25-26  illustrate yet another alternative exemplary embodiment of the present invention wherein the mounting portions of the backing plate comprise integral locking pins  36 .  
         [0072]      FIGS. 27-29  illustrate yet another alternative exemplary embodiment wherein the backing plate comprises integral locking pins  36 , which are configured to be received within an opening  120  of a mounting member  30  and each locking pin  36  provides a guiding feature, a locking feature via opening  62  and a horn switch feature via a conductive tip portion  122  which makes contact with an un-insulated portion  124  of a wire  48  as the backing plate moves towards the mounting members. As illustrated, openings  62  engage a retaining member  126  configured and positioned to engage openings  62 .  
         [0073]     This embodiment reduces the stack tolerance of the airbag module through the incorporation of a horn contact mechanism into the attachment features of the airbag module. The backing plate of these embodiments may be constructed in accordance with the disclosure and teachings of U.S. provisional patent application Ser. No. 60/608,595, filed Sep. 10, 2004, the contents of which are incorporated herein by reference thereto.  
         [0074]     Referring now to  FIGS. 30-38  other alternative exemplary embodiments of the present invention are illustrated.  FIGS. 30 and 31  simply show, in schematic form, a carrier  213   a  for a gas generator of an airbag module  213  and also a contact bridge  211   a  associated in the context of this application with a steering wheel  211 .  
         [0075]     The steering wheel arrangement includes a so-called “isolated floated horn” mechanism by which a schematic illustrated vehicle horn  235  is actuated by depressing the airbag module and thus moving the generator carrier  213   a  downwardly in the direction of the contact bridge  211   a.    
         [0076]     The generator carrier  213   a  and the contact bridge  211   a  are provided at their mutually confronting sides with electrical contact wires  215 ,  217  which are laid, at least regionally, in a plane which extends perpendicular to the steering wheel axis  233 . The contact wires  215 ,  217  are attached by means of individual electrically insulating holders  221  to the generator carrier  213   a  and to the contact bridge  211   a  respectively. The individual holders  221  are either integral components of the generator carrier  213   a  and the contact bridge  211   a  or separate components which are secured to them following the manufacture of the generator carrier  213   a  and the contact bridge  211   a.    
         [0077]     The connection between the contact wires  215 ,  217  and the holders  221  takes place by clipping or latching.  
         [0078]     Alternatively, the holders  221  could also be omitted and the contact wires  215 ,  217  could be directly clipped or latched to the generator carrier  213   a  and the contact bridge  211   a . In accordance with a further alternative it is possible to dispense with such shape locked and/or force-transmitting connections and the contact wires  215 ,  217  could be integrated, during or after the manufacturing of the generator carrier  213   a  and the contact bridge  211   a , into the generator carrier  213   a  or the contact bridge  211   a  respectively, by injecting plastic material around them.  
         [0079]     The contact wires  215 ,  217  are laid in such a way that they cross at at least one contact position  219 . At this contact position  219  the contact wires  215 ,  217  consequently enter into contact with one another when the airbag module  213  or the generator carrier  213   a  is depressed by the user from the open position of  FIG. 31  and pressed towards the steering wheel  211 , i.e. the contact bridge  211   a , into the closed position in accordance with  FIG. 30 . Through the contact of the contact wires  215 ,  217  at the contact position or contact positions  219  an electrical circuit is closed and the vehicle horn is actuated.  
         [0080]     An advantage of this “contact wire switch” in accordance with the invention in comparison to customary contacting types, such as microswitches or so-called “snap-frogs” is the pronounced contactile feeling. Moreover, the unit costs for the steering wheel unit or the component assembly which is to be installed at the steering wheel can be considerably reduced as a result of the invention.  
         [0081]     In order to improve the electrical operability the contact wires  215 ,  217  are respectively provided at the contact position  219  or at the contact positions with a welded on contact piece  223 , for example of a silver alloy. A high working life and ideal contact characteristics can be hereby ensured with-out the danger of problems with voltage drops and transition resistances.  
         [0082]     As the example of  FIG. 32  shows the conductors  215 ,  217  which are attached via holders  221  can be supported in the region of the contact position or touching position  219  by support elements  225  at the airbag module  213 , or at the generator carrier  213   a , and at the steering wheel  211 , or at the contact bridge  211   a.    
         [0083]     One alternative exemplary embodiment is shown in  FIG. 33 . Here the airbag module  213  or the generator carrier  213   a  and the steering wheel  211  or the contact bridge  211   a  are provided with abutments  227  through which a minimal spacing is predetermined in the direction of the steering wheel axis. In this manner the actuating load for the conductors (contact force)  215 ,  217  is predetermined.  
         [0084]      FIG. 34  shows an example in which the conductors  215 ,  217  are each provided in the region of the contact position  219  with a contact rivet  229 . Respective support elements  225  are provided for the conductors  215 ,  217  on both sides of the conductor section provided with the rivet  229 .  
         [0085]     In the example of  FIG. 35  the conductors  215 ,  217  are each provided in the region of the contact position  219  with a brazed or welded contact section  231 .  
         [0086]     In the above the clipping or latching of contact wires  215 ,  217  to the holders  221  has been mentioned. Alternatively it is also possible, during the manufacture, to mould the plastic material of the holders  221  around the wires  215 ,  217 . Holders  221  of plastic can in particular also be injection moulded onto sheet metal parts, for example of a contact bridge. During this the injection molding can simultaneously take place around the wires  215 ,  217 .  
         [0087]     The holders  221  from the contact wires  215 ,  217  can also be manufactured of a different material. In particular an electrically insulating material for the holder  221  is not required. In practice the airbag module is frequently electrically insulatingly mounted and the generator carrier consists of metal. In these cases no electrical insulation is required between the relevant contact wire  217  and the airbag module for the generator carrier, so that the holders  221  for the contact wires  217  can be manufactured from any desired material and in particular also from electrically conducting material.  
         [0088]     Furthermore, mechanical end stops can be provided as protection for the contacts of the contact positions  219  between the airbag module and the steering wheel or its components and restrict the actuation path, for example during aggressive or panic-like actuation of the vehicle horn. An excessive loading of the contact positions  219 , in particular an excessive extension or bending of the contact wires  215 ,  217  is hereby avoided.  
         [0089]     In the foregoing the steering wheel side provision of the contact bridge has been mentioned as a variant of the invention. In this variant the contact bridge can thus be regarded as a component of the steering wheel. An inverted arrangement is likewise possible in accordance with the invention and in many cases represents the preferred embodiment. For example, in the inverted variant the floating horn system and thus the contact bridge are connected to the airbag module.  
         [0090]      FIG. 36  schematically shows a contact system in accordance with the invention in its inbuilt environment. A contact bridge  211   c  is attached to the steering wheel  211 . The constructional space  245  present between the con-tact bridge  211   c  and the steering wheel  211  can be utilized for a so-called vibration damper, which will not be discussed in more detail here. With the airbag module  213  “floatingly” mounted on the steering wheel and/or on the contact bridge  211   c  by means of spring arrangements  247 , the horn switch formed by the contact system in accordance with the invention can be actuated by depressing it as a whole (“floating horn”).  
         [0091]     In each case one or more contact wires  215  and  217  respectively held in individual holders  221  are attached to the upper side of the contact bridge  211   c  and to the lower side of the airbag module  213 . The wires  217  at the airbag module side and the wires  215  at the steering wheel side cross at a plurality of contact positions  219 .  
         [0092]     When the user depresses the airbag module  213  as a whole for the actuation of the vehicle horn and moves it in the direction of the fixed contact bridge  211   c  of the steering wheel  211 , then the wires  215 ,  217  enter into electrical contact at at least one contact position  219 , whereby the horn switch formed by this contact system is closed.  
         [0093]     The airbag module  213  is provided in this example with additional functional switches  241  which can alternatively also be attached to the steering wheel  211 .  
         [0094]      FIGS. 37 and 38  show an embodiment which has already been discussed in the introduction and which is distinguished from the above-explained variants amongst other things in that two contact wires  215 ,  217  are attached to a common component  237  which will be referred to generally as the “carrier” in the following. In other respects  FIG. 38  corresponds to  FIG. 36 . The carrier  237  can either be the steering wheel, the airbag module or a component of one of these two components, for example a contact bridge  211   a  (as in  FIG. 38 ).  
         [0095]     For the actuation of the electrical functional unit, in particular of the vehicle horn no relative movement of the two wires  215 ,  217  as a whole takes place. On the contrary—if the carrier  237  is, for example, the steering wheel  211  ( FIG. 38 )—the upper wire  217  disposed in  FIG. 37  closer to the airbag module is pressed downwardly in the region of the contact position  219  against the lower wire  215 . The upper wire  217  thus bends and can—as shown in  FIG. 37 —be made thinner than the lower wire  215  for which a support  239  can be provided disposed at the contact position  219 . For the loading of the wire  217  which is to be bent, the relevant component—in the example of  FIG. 38  the airbag module  213 —can be provided with a suitably positioned and shaped, for example spigot-like or pin-like actuating projection  243 , which, during the relative movement between the airbag module  213  and the steering wheel  211  loads the relevant wire  217  at the contact position  219  and thereby presses it against the other wire  215  in order to produce the desired electrical contact between the two wires  215 ,  217 .  
         [0096]     In accordance with  FIG. 38  contact wires  215 ,  217  which cross at a plurality of contact positions  219  are held in individual holders  221  and are attached to the upper side of the contact bridge  211   c . The airbag module  213  is provided at its lower side with a plurality of actuating projections  243  which, at each contact position  219 , press the upper wire  217  against the lower wire  215  when the user presses the airbag module  213  as a whole for the actuation of the vehicle horn and moves it in the direction of the fixed contact bridge  211   c  of the steering wheel  211  and thus closes the horn switch.  
         [0097]     While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the present application.