Abstract:
An igniter ( 10 ) for use in a protecting device for vehicle occupants comprises a member selected from the group of a base body ( 12 ) and a base body ( 12 ) surrounded by a base body ring ( 42 ), as well as contact pins ( 32 ) received in the base body ( 12 ), a sleeve ( 14 ) adjoining the base body ( 12 ) or the base body ring ( 42 ) and for receiving an ignition charge ( 16 ), and a cover ( 22 ) closing the sleeve ( 14 ). The base body ( 12 ) and the sleeve ( 14 ), or the base body ring ( 42 ) and the sleeve ( 14 ), are made in one piece with each other.

Description:
FIELD OF THE INVENTION  
         [0001]    The invention relates to an igniter for use in a protecting device for vehicle occupants, comprising a base body and contact pins received in the base body or a base body ring surrounding the base body with the contact pins, a sleeve adjoining the base body or the base body ring and for receiving an ignition charge, and a cover closing the sleeve.  
         BACKGROUND OF THE INVENTION  
         [0002]    A conventional ignition device for the propellant charge of an occupant protecting device is described in DE 101 11 715 A1, for example. The ignition device of this type has a housing with a base and a metal cap joined therewith. Placed on the base is a fitting ring which receives contact pins that are fused in an insulating glass material, the heads of which are connected with a resistance wire. A plastic sleeve placed on the fitting ring forms together with the metal cap an ignition chamber which is filled with ignition material. The ignition material is in contact with the resistance wire. Usually, the cap and the fitting ring are welded to each other such that a connection is formed which is gas-tight and impervious to fluids. The contact pins projecting out of the base can be partially provided with a plastic coating.  
         SUMMARY OF THE INVENTION  
         [0003]    The known igniters have the disadvantage that they are made up of numerous components and for that reason can not be produced at favorable costs. In contrast to this, the present invention makes available an igniter for use in a protecting device for vehicle occupants, the production of which is simple and attractively-priced due to its uncomplicated construction. According to the invention, there is provided an igniter comprising a base body and contact pins received in the base body and, optionally, a base body ring surrounding the base body, a sleeve adjoining the base body or the base body ring and for receiving an ignition charge, and a cover closing the sleeve, which is characterized in that the base body and the sleeve or the base body ring and the sleeve are made in one piece with each other.  
           [0004]    The igniter according to the invention has the advantage that the sleeve serving for receiving the ignition charge does not have to be welded any more with the base body or the base body ring, respectively, whereby an additional production step is dispensed with. Moreover, the construction according to the invention is mechanically more stable and has less susceptibility to failure.  
           [0005]    The base body and the sleeve are preferably formed together in one piece from plastic, resin or another material for electrical insulation. In this embodiment, the base body ring can be dispensed with completely, as it is defined by a first end of the sleeve. Manufacture of the igniter according to the invention can be performed according to usual processing techniques in an injection-molding mold. This makes possible a particularly simple production feasibility.  
           [0006]    As an alternative to this, the base body can be formed from glass, as is described in prior art, and can be surrounded by a base body ring. In that case the base body ring and the sleeve together are made in one piece from metal. The contact pins are fused in the base body ring so as to form a connection which is gastight and impervious to fluids. In this embodiment, the one-piece component consisting of base body ring and sleeve can also serve at the same time as the outer housing of the igniter. In this case, too, the construction of the igniter is realized with few components and, hence, a low-cost production is achieved.  
           [0007]    It is particularly preferred that the cover is received in one axial end of the sleeve opposite to the base body. Further, the cover can have an edge-surrounding shoulder which directly adjoins the axial end of the sleeve and is connected therewith. The connection can be effected by welding, gluing, soldering or other joining techniques.  
           [0008]    The igniter is tightly sealed by the cover, and depending on the demands, also hermetically tightly sealed. The cover further can have a predetermined breaking point which allows a defined opening behavior. The cover additionally may include a device by means of which the ignition jet, generated upon activation of the ignition charge, is guided in a predefined direction.  
           [0009]    The contact pins usually are connected to an ignition bridge which is in contact with the ignition charge. The ignition bridge preferably is a resistance bridge, a spark bridge or a semiconductor bridge.  
           [0010]    A gap may be provided between the ignition bridge and the base body, this improving the adherence of the ignition charge in the sleeve and the contact between the ignition bridge and the ignition charge. The fixation of the ignition charge in the sleeve can also be improved by an appropriate design of the surface of the base body or of the inner wall of the sleeve, for instance by knobs applied on the inner wall, or by longitudinal or transverse grooves.  
           [0011]    The contact pins finally can have at least one curved section in the base body, or squeezed or upset portions, or other irregular surface structures. The tightness and the mechanical stability of the igniter are further improved thereby. This prevents the contact pins from being pressed out of the hollow body easily.  
           [0012]    For producing the igniter according to the invention there is provided a prefabricated component made up of the base body and the sleeve formed in one piece therewith, with the contact pins being received in the base body and adjoining the ignition chamber delimited by the base body and the sleeve. An alternative is to provide a component which consists of the charge sleeve formed in one piece with the base body ring, with a base body made of glass and fused in therein. Here too, the base body of glass already receives the contact pins which adjoin the igniter chamber formed by the base body and the charge sleeve.  
           [0013]    In a next step the ignition bridge is axially introduced into the component and firmly connected with the contact pins by soldering, welding or gluing. In case there is used a resistance wire as the ignition bridge, the ignition wire can be radially inserted into the ignition chamber through lateral openings in the sleeve and likewise be connected with the contact pins by soldering, welding or gluing. In the completed igniter, the lateral openings in the charge sleeve can function as radial discharge openings.  
           [0014]    Loading the ignition chamber with the ignition charge can be performed by a wet processing, for example by immersion, or by the pulverulent ignition charge being pressed in. Subsequently, the cover is placed into the charge sleeve and joined therewith by gluing, soldering or welding so as to form a connection which is impervious to humidity. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    Further advantages of the invention will be apparent from the following description of preferred embodiments and the appended drawing in which:  
         [0016]    [0016]FIG. 1 shows a section taken through an igniter of the invention according to a first embodiment;  
         [0017]    [0017]FIG. 2 shows a section taken through an igniter according to a second embodiment of the invention;  
         [0018]    [0018]FIG. 3 shows a section taken through an igniter according to a third embodiment of the invention;  
         [0019]    [0019]FIG. 4 shows a section taken through an igniter according to a fourth embodiment of the invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]    In FIG. 1 there is shown an igniter  10  according to the invention, which has a base body  12  and a sleeve  14  for receiving an ignition charge  16 . In the embodiment shown here, the base body  12  and the sleeve  14  are formed together in one piece from plastic. As is shown here, the ignition charge  16  can be composed of a primary ignition composition  18  and a secondary ignition composition or booster charge  20 . It is also possible, however, to use a uniformly composed ignition material, or one which consists of more than two components.  
         [0021]    A cover  22  is inserted in one axial end of the sleeve  14  opposing the base body  12  and connected with the sleeve  14  by welding, gluing or soldering so as to form a connection impervious to humidity. Thus, the cover  22  closes off the ignition chamber  24  delimited by the base body  12  and the sleeve  14 . In the embodiment illustrated in the left-hand half of FIG. 1, the cover has a disc-shaped section  26  resting on the ignition charge  16  and a wall section  28  arranged essentially at right angles thereto. The wall section  28  directly adjoins the inner surface of the sleeve  14  and forms a connection with this which is impervious to humidity. On the other hand, in the embodiment illustrated in the right-hand half of FIG. 1, the cover  22  has an edge-surrounding shoulder  30 . In this embodiment the cover  22  rests against the inner surface of the sleeve  14  and against the end surface thereof.  
         [0022]    Two contact pins  32  are received in the base body  12  in a gas-tight manner and in a fashion impervious to fluids. One end each of the two contact pins  32  adjoins the ignition chamber  24  and is connected to an ignition bridge  34 , preferably a resistance bridge, a spark bridge or a semiconductor bridge. In the embodiment shown here, the ignition bridge  34  in the ignition chamber  24  directly rests on the base body  12 . The ignition charge  16  and the ignition bridge  34  have direct contact with each other. The free ends, projecting out of the base body  12 , of the contact pins  32  serve for being connected with a corresponding plug representing an interface to a detecting and evaluating unit. In case of an accident of the vehicle, an electrical pulse is delivered via the plug, which will flow through the ignition bridge  34 . In the process, the latter is heated and ignites the ignition charge  16 . Due to the increase in pressure in the ignition chamber  24  the connection between the sleeve  14  and the cover  22 , or a predetermined breaking point in the cover  22 , will be torn open. The released combustion products of the ignition charge  16  will then ignite the propellant charge of an occupant protecting device.  
         [0023]    In the second embodiment of the igniter  10  according to the invention shown in FIG. 2, the contact pins  32  received in the base body  12  have a curved section  26 . Thereby the connection between the contact pins  32  and the base body  12  is significantly improved and the mechanical stability of the igniter  10  is enhanced. Here, the contact pins  32  can be pressed out of the base body  12  not so easily. All other parts of the igniter shown in FIG. 2 correspond in terms of their construction and function to those of the first embodiment.  
         [0024]    In the embodiment of the igniter  10  according to the invention shown in FIG. 3, the contact pins  32  project into the ignition chamber  24 . With this, a gap  38  is formed between the ignition bridge  34  and the base body  12 , which gap likewise is filled with ignition charge  16 . Thereby the ignition charge  16  can be reliably fixed within the ignition chamber  24 . What is more, the contact between ignition charge  16  and ignition bridge  34  is improved.  
         [0025]    Moreover, the sleeve  14  has its inner surface provided with a bead  40  oriented radially inwards, which preferably is formed so as to be continuously surrounding. The bead  40  likewise serves for additional fixation of the ignition charge  16  in the ignition chamber  24 . As further means of fixation there can be provided transverse grooves, longitudinal grooves or knobs formed, for example, in the bottom or on the side walls of the ignition chamber  24 .  
         [0026]    All other parts of the embodiment of the igniter shown in FIG. 3 correspond in terms of their construction and function to the parts shown in FIG. 1, with identical parts being referenced by the same reference symbols.  
         [0027]    In FIG. 4 there is shown an igniter  10  according to the invention, which has a base body  12  with contact pins  32  that are received therein in a gas-tight manner and in a fashion impervious to humidity. Here, the base body  12  is formed from glass and received in a base body ring  42 . The base body ring  42  adjoins a sleeve  14  for receiving an ignition charge  16  and is formed in one piece therewith from metal. Also in this case the ignition charge  16  can be composed of a primary ignition composition  18  and a secondary ignition composition or booster charge  20 .  
         [0028]    Inserted into the axial end of the sleeve  14  opposite the base body  12  is a cover  22  which is connected with the sleeve  14  by welding, gluing or soldering. Just like in the embodiments shown above, the cover can have a disc-shaped section  26  and a wall section  28  arranged substantially at right angles thereto. The wall section  28  rests against the inner surface of the sleeve  14  and is connected with this by welding, gluing or soldering so as to form a connection impervious to humidity. This is illustrated in the left-hand half of FIG. 4. As an alternative to this, an edge-surrounding shoulder  30  can be formed on the cover. The cover  22  is then inserted into the sleeve  14  with the shoulder  30  and rests against the inner surface of the sleeve  14  and against the end face thereof. The contact region between the cover  22 , or respectively between the shoulder  30  and the sleeve  14 , is closed off here by welding, gluing or soldering so as to be impervious to humidity.  
         [0029]    In the embodiment shown here, the base body  12 , the sleeve  14  and the cover  22  delimit the ignition chamber  24 . At the bottom of the ignition chamber  24  and on the base body  12 , there is provided an ignition bridge  34  to which the contact pins  32  are connected. The opposite, free ends of the contact pins  32  are inserted into a corresponding plug, as described above. The ignition bridge  34  can be a resistance wire, a spark bridge or a semiconductor bridge. It makes direct contact with the ignition substance  16  in order to ensure a reliable ignition.  
         [0030]    For a better sealing of the igniter  10 , the contact pins  32  projecting out of the base body  12  as well as the base body ring  42  and parts of the sleeve  14  can be provided with a plastic coating  44  which may define the assembly dimensions of the igniter. The contact pins  32  can have a curved section in the base body  12  or a surface structure modified in another way, just like in the embodiment described in connection with FIG. 2. A gap can be provided between the ignition bridge  34  and the base body  12 , as is shown in FIG. 3.  
         [0031]    For better fixation of the charge  16  in the ignition chamber  24 , the sleeve  14  finally can be provided with recesses or bulged-out portions  46 . Another possibility is, as described above, to form longitudinal grooves, transverse grooves or knobs on the base body  12  and the inner surface of the sleeve  14 , respectively.  
         [0032]    For manufacture of the igniter as shown in FIG. 4, the base body  12  together with the contact pins  32  is fused in the base body ring  42  defined by a lower end of the sleeve  14 . Thereafter, the ignition bridge  34  is introduced into the sleeve  14  in axial direction and conductively connected with the ends of the contact pins  32  by gluing, for instance. Next, the primary ignition composition  18  and, optionally, the secondary ignition composition or the booster charge  20  is introduced in liquid or solid form into the sleeve  14 , so that a safe contact with the ignition bridge  34  is guaranteed. Finally, the cover  22  is inserted in the free axial end of the sleeve  14  opposite the base body  12  and is connected therewith so as to form a connection impervious to humidity. For better sealing, the contact pins  32  projecting out of the base body  12  can be provided in an injection-molding mold with an injection-molded plastic coating  44 .  
         [0033]    The igniter described above has a simple construction and therefore can be produced at favorable costs.