Abstract:
A restraining system for a motor vehicle with a seat belt retractor that accommodates the one end of a seatbelt component, which has a tightening device having a belt shaft and a drive cable connected to the belt shaft, in which a sleeve ( 26 ) that enlarges the outer circumference of the shaft element (25) is slid onto one end of the shaft element ( 25 ) and is axially and radially fixed to the shaft element ( 25 ), while the wall thickness of the sleeve ( 26 ) is dimensioned in such a way that the drive radius of the shaft element ( 25 ) and a reduction in speed of the tightening drive is provided as compared with a cable wrapped onto the belt shaft.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to German patent application Nos. DE 10 2005 050 426.4, filed Oct. 21, 2005, DE 10 2005 051 042.6, filed Oct. 25, 2005, and PCT/EP2006/009843, filed Oct. 12, 2006. 
     FIELD OF THE INVENTION 
     The invention relates to a retention system for a motor vehicle with a seat belt retractor accommodating one end of a seatbelt component which has a belt shaft and a pretensioner device having a drive connection with the belt shaft. 
     BACKGROUND OF THE INVENTION 
     A restraining system of the aforementioned type is described, for example, in DE 103 04 943 B3. With the known restraining system, the associated seat belt retractor is part of an end fitting pretensioner in which the end of the seat belt to be fixed on the motor vehicle structure is fixed on the retractor shaft, so that this end of the seatbelt is wound up on the shaft upon actuation of the pretensioner drive and is tightened in this way. The locking of the shaft element with the seat belt retractor housing is undertaken in such a way that the locking element is arranged in the radial interior of the shaft element, which has a hollow configuration, and is pretensioned by means of a passage opening configured in the shaft element by spring action over the outer circumference of the shaft element until it engages in the associated gearing of the housing leg that supports the belt shaft. Consequently, the locking element is in a permanent locking with the seat belt retractor housing so that the end of the seat belt is correspondingly fixed and therewith fixedly mounted on the motor vehicle. When the pretensioner drive is activated, the locking element ratchets away through the gearing of the housing leg in the corresponding direction of the belt shaft, while in the event of a rotation of the belt shaft in the belt withdrawal direction after completing the pretensioning rotation, the immediate locking of the belt shaft takes place. 
     It is an object of the invention to increase the pretensioning force of a restraining system of the type described above. 
     This object, including the advantageous embodiments and further developments of the invention, is attained with the features of the present invention described herein. 
     SUMMARY OF THE INVENTION 
     The invention provides in its basic conception to slide a sleeve, which enlarges the outer circumference of the shaft element in this area and is immovably axially and radially connected to the shaft element, on one end of the shaft element, in which the thickness of the wall of the sleeve is dimensioned in such a way that the drive radius of the shaft element is enlarged and a reduction in speed of the pretensioner drive is established as compared with wrapping the pretensioner cable directly onto the shaft element. Due to the arrangement of the sleeve, the tightening radius and therewith the tightening force are enlarged when the diameter of the shaft element, and therefore the winding radius of the wound-up belt webbing, remain constant because the drive cable is wound around the sleeve at a greater radial distance with respect to the central axis of the shaft element. 
     According to an exemplary embodiment of the invention, the belt shaft is configured as a hollow shaft with a locking element arranged in the interior of the shaft element, as is known from the prior technology as described by DE 103 04 943 B3, in which the sleeve is slid on the end that accommodates the locking element and is mounted in the housing leg, and has an opening that is flush with the passage opening of the shaft element for the locking element. 
     According to exemplary embodiments of the invention, it can be provided with respect to mounting of the drive cable on the belt shaft, that the drive cable extends through the sleeve and is mounted on the shaft element, or that the drive cable is mounted directly on the sleeve. It can also be provided that the drive cable is mounted both on the shaft element and the sleeve. 
     To the extent that a supporting of the locking element on the shaft element is to be ensured for transferring load from the belt shaft to the seat belt retractor housing, the locking element can be supported in the engaged state with the gearing of the housing leg on an edge region of the passage opening of the shaft element, which is configured as a nose. 
     As an alternative, the locking element can be braced in the engaged state with the gearing of the housing leg at an edge region of the opening configured in the sleeve, which is configured as a nose. 
     An especially secure force transmission results according to one embodiment of the invention when the locking element is braced in the engaged state with the gearing of the housing leg on the edge of the passage opening of the shaft element as well as the opening configured in the sleeve, which is configured as a joint nose. 
     With regard to the radial and axial fixation of the sleeve on the shaft element, it can be provided according to an exemplary embodiment of the invention that the connection of the sleeve and the shaft element is created by means of projections stamped out of the sleeve radially inward extending into associated recesses of the shaft element. 
     As long as the projections of the sleeve are inclined in axial direction of the shaft element, it is practical to arrange two projections with an opposite oriented inclination. 
     The force transmission is improved overall as long as, according to an exemplary embodiment of the invention, a multitude of recesses and projections are distributed over the circumference of the shaft element and the sleeve. 
     In a further embodiment of the invention, it is provided that two annular closed retaining elements with a smooth internal circumference enclosing the housing leg as well as the deflected locking element between them are slid on the shaft element for axial position securing of the belt shaft on the housing leg lockingly interacting with the locking element, in which the shaft element has a stop for the axial fixation of the internal retaining element, which comes to lie between the stop and the housing leg, and the outer sleeve lying outwardly against the housing leg as a further retaining element is fixed using an anti-sliding safety on the shaft element. The advantage that due to the axial shaft fixing device, an axial displacement of the belt shaft relative to the retractor housing is ruled out, especially due to the action of the tightening device coupled to the belt shaft. An axial shaft fixing device such as this is basically known from the generic restraining system disclosed in DE 103 48 461 A1. 
     As long as according to an exemplary embodiment of the invention it is provided that the stop provided on the shaft body is formed by stamping the shaft element as a radial elevation of the circumference of the shaft element, the advantage that the stop can be economically manufactured without an additional component is provided. 
     In accordance with a further exemplary embodiment of the invention, it is provided that the inner retaining element is configured as a retaining ring which can be slid on the shaft element, and the outer retaining element is configured as a sleeve which can be slid against the housing leg on the retaining element, while the drive cable is wound on the outer circumference of the sleeve. In this case, it can be provided that the anti-sliding safety for the sleeve consists of a cable suspension configured at the end of the drive cable, which passes through the sleeve as well as the shaft element of one opening in each case. The advantage that the anti-sliding safety is likewise realized without an additional component is associated with this. 
     According to an exemplary embodiment of the invention, it is provided that the retaining elements are provided in each case at their front end that faces the housing leg with an axial facet, in such a way that a linear installation of the retaining element on the housing leg results. In this way, friction losses due to the rotation of the belt shaft are minimized. It can moreover be provided that the facet of the retaining elements in each case bridges the opening configured in the shaft element for penetration of the toothed lock washer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings are depicted exemplary embodiments of the invention, which will be described in the following, and wherein; 
         FIG. 1  illustrates an overall view of a seat belt retractor and pretensioning device in accordance with the present invention, 
         FIG. 2  illustrates the device shown in  FIG. 1  in a side view, 
         FIG. 3  illustrates the latching element of the seat belt retractor shown in  FIG. 1 , 
         FIG. 4  illustrates the latching plane of the seat belt retractor in accordance with this invention shown in section, and 
         FIG. 5  illustrates an exemplary embodiment of the belt shaft with an axial locking device in section view. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The seat belt retractor and a pretensioning device  10  in accordance with this invention, which can be seen in  FIG. 1 , the seat belt retractor consists of a U-shaped seat belt retractor housing  11 , in whose housing legs  12  a belt spool or shaft  13  is mounted, on which a belt webbing  14  is wound. A belt buckle  15  is mounted on the free end of the belt webbing  14 , into which or from which a locking tongue  16  can be inserted or detached, wherein the locking latch plate tongue  16  is mounted on a seat belt  17 . Seat belt arrangements such as that described above are known. In order to be able to subject the belt buckle  15  to a tightening by winding up the belt webbing  14  on the belt shaft  13 , a pretensioning device  18  is fastened on a housing leg  12  consisting of a pretensioner tube  19  and a gas generator receptacle  20 . The connection between the pretensioning device  18  and the belt shaft  13  is carried out by means of a drive wire or cable  22 , which is wound on a shaft extension  24  of the belt shaft  13  and its end is affixed to the shaft. 
     As can also be seen in  FIG. 2 , the end of the drive cable  22  attached to the pretensioning device  18  is guided into the pretensioner tube  19  and is connected herein to a piston  21 , which can move within the tightening tube  19 . A gas generator  23  is arranged in the gas generator receptacle  20  of the pretensioner tube  19 , which upon activation releases gas, which drives the piston  21  in the pretensioner tube  19 , so that the drive cable  22  is unwound from the shaft extension  24  of the belt shaft  13  and consequently causes the belt shaft  13  to rotate which tightens or pretensions webbing  14 . 
     The belt shaft  13  has a shaft element  25 , which has a hollow configuration, on which the belt webbing  14  is wound. A locking element  27 , which passes with at least one tooth through a passage opening  28  arranged in the shaft element  25 , is arranged within the plane of the housing leg  12  in the shaft element  25 , through which passes the shaft extension  24 . A sleeve  26  on whose outer circumference the drive cable  22  is wound, is slid on the shaft extension  24 , which overlaps the shaft extension  24  in order to enlarge the tightening radius. The sleeve  26  has an opening  29  for the passage of the locking element  27 , which is flush with the passage opening  28  of the shaft element  25 , so that the locking element engages with the allocated gearing of the housing leg  12  when it is pivoted out into its locking position. As is not shown in detail, the locking element  27 , according to the description of DE 103 04 943 B3, which is herewith also being made into an object of the present disclosure, is pretensioned by a spring element into its pivoted out locking position, so that the locking element  27  ratchets away over the gearing of the housing leg  12  when the belt shaft  13  is rotated, and brings about the immediate locking of the belt shaft  13  in the belt withdrawal direction when the belt shaft  13  is rotated after the pretensioning rotation has ended. 
     As can be inferred in more detail from  FIG. 3 , the sleeve  26  is axially and radially fixedly mounted on the shaft element  25 , in that projections  30  are stamped in the plane of the shaft element  25 , which project from the sleeve  26  radially inwardly, which in turn engage into recesses  31  formed in the sleeve  26 . Two diametrically opposite projections  30  engaging with recesses  31  are represented in the shown exemplary embodiment, in which the projections  30  are aligned inclined in the axial direction of the shaft element  25  in such a way that their longitudinal axis intersects the longitudinal axis of the shaft element  25 . The mutually opposite projections  30  are preferably arranged therein with an opposite oriented inclination, so that the sleeve  26  is axially and radially immovably fixed on the shaft element  25 . In  FIG. 3  can furthermore be seen a cable end fitting or bushing  32  for the drive cable  22 , which in the shown exemplary embodiment is positioned in the interior of the shaft element  25 , so that the drive cable  22  runs toward its outer circumference through a corresponding clearance in the sleeve  26 . 
     In  FIG. 4  can finally be seen the arrangement and mounting of the locking element  27  in the hollow shaft element  25 , which corresponds to the description in the representative DE 103 04 943 B3. Here, the locking element  27 , which is mounted with a bearing arrangement  35  in a perforation  36  formed in the shaft element  25  as well as in the sleeve  26 , respectively, is supported when engaged with the gearing  37  of the allocated housing leg  12 , on an edge region of the opening  29  of the sleeve  26 , which is configured as an inwardly curved nose  33  that engages in a pocket  34  formed in the locking element  27 . Consequently, the introduction of the bracing force is carried out, on the one hand, into the sleeve  26 , and on the other hand, via the bearing attachment  35  into the sleeve  26  as well as into the shaft element  25 . 
     As can be seen in  FIG. 5 , the axial locking device of the belt shaft  13  is positioned on the housing leg  12  that interacts with the locking element  27 , and namely through an internal retaining element  41  slid on the shaft element  25 , which is configured, with the exception of the passage opening  28 , with a closed circumference. The internal retaining element  41  is located in the interior of the housing frame  11  between the housing legs  12  and is configured as a closed retaining ring, which is supported on a stop  42  configured by stamping or forming of the shaft element  25 . The sleeve  26 , on whose outer circumference the drive cable  22  is wound, is slid on the outside of the shaft extension  24 , which projects beyond the housing leg  12 . The drive element, which is provided at its end with a cable fitting  44 , is guided into the interior of the shaft element through an opening  43  formed in the sleeve  26  as well as in the shaft element  25  and is fixed by means of the cable fitting  44 . Due to this configuration, the cable fitting  44  together with the drive cable  22  extending from it acts at the same time as an anti-sliding safety for the external sleeve  26 , so that after the installation is complete, the sleeve is immovably fixed on the shaft element  25 . 
     In order to reduce friction losses during the rotation of the belt shaft  13 , the internal retaining element  41  as well as the external sleeve  26  are provided with a radial facet  45  which respectively face the housing leg  12 , so that a basically linear installation of the two retaining elements  41  or  26  on the housing leg  12  is achieved. Here, the facet  45  is formed in such a way that the passage opening  28 , which is configured in the shaft element  25  to allow the passage of the locking element  27 , is bridged in each case. 
     The features of object of these documents, which are disclosed in the previous description, the patent claims, the abstract, and the drawings, can be essential individually and also in any desired combinations for the realization of the invention in its various embodiments.