Abstract:
An automatic seatbelt retractor has a winding shaft for winding and unwinding seatbelt webbing and at least one pre-locking device for pre-locking the winding shaft against further rotation and for driving into a main locking means. Forces exerted by the seatbelt webbing are introduced into a frame connected to a vehicle. The pre-locking device has an actuating device that actuates at least one securing component as a function of a predetermined extracted length of the seatbelt webbing from the winding shaft to hold the winding shaft in the pre-locking position. For actuation of the securing component by the actuating device a single intermediate element, which can be moved reversibly by the actuating device from a rest position into a locking position, is provided between the actuating device and the securing component.

Description:
FIELD OF THE INVENTION 
     The present invention relates to an automatic seatbelt retractor for a seatbelt system in a motor vehicle. 
     BACKGROUND OF THE INVENTION 
     Automatic seatbelt retractors return a seatbelt automatically back to its&#39; original position after use. An automatic seatbelt retractor should prevent catching in the otherwise slack seatbelt located inside a vehicle when getting in and out, or loading and unloading, etc. Of course, automatic seatbelt retractors contain those components of a seatbelt system that prevent a forward movement of a person secured by the seatbelt when the motor vehicle is subjected to rapid deceleration. A locking device that prevents unwinding of the seatbelt in such cases carries this out. To distinguish from further locking devices which may be provided, this module is described as the main locking means. 
     Further locking devices of this type can include a so-called vehicle-sensitive and/or webbing-sensitive locking or blocking device. Both blocking devices serve to prevent a forward movement of the person secured by the seatbelt system even during decelerations of the motor vehicle which are lower than the decelerations releasing the main locking means. As these blocking devices come into action before activation of the main locking means, they are frequently also described as pre-locking or pre-blocking devices. The respective pre-blocking device is able to lock the seatbelt system to prevent further unwinding of the seatbelt webbing also via the main locking means. 
     As the seatbelt frequently secures not only a person but also child seats or other bulky objects transported inside the vehicle, a further pre-locking device is frequently provided in the known automatic seatbelt retractors, in order to lock the automatic seatbelt retractor against further extraction after extraction of a predetermined length of seatbelt webbing from the winding shaft. Although the seatbelt can be retracted again until the child seat and/or the bulky object is firmly secured by the seatbelt, the seatbelt cannot be further extracted. This prevents the object secured in this way from moving during deceleration of the motor vehicle. This pre-locking device is frequently referred to as a child seat locking device. 
     DISCUSSION OF THE PRIOR ART 
     European Patent 0 625 449 discloses an automatic seatbelt retractor of the type mentioned at the outset with a child seat locking device in which a rotatably mounted securing lever is provided. The securing lever acts at both ends and can be pivoted from a rest position into a locking position according to the predetermined extracted length of the seatbelt by means of an actuating device. The securing lever is biased into the rest position by means of a spring, exceeds its&#39; dead center position during actuation thereof by the actuating device and is then biased into the locking position again by the spring. The securing lever engages teeth of a wheel non-rotatably connected to the winding shaft, the teeth on the exterior of this wheel being in the form of saw teeth. The saw teeth point in the unwinding direction. The securing lever can therefore pass over the wheel in the take-in direction of the seatbelt webbing as the locking position is released and can finally pivot back into its&#39; rest position. 
     This well functioning child seat locking device contains, in addition to the actuating device, two separate components that are small in construction owing to the restricted space in automatic winding devices of this type. This makes assembly, in particular of the springs, difficult and time-consuming. This is a drawback, in particular if assembly is to be carried out using automatic assembly devices. 
     SUMMARY OF THE INVENTION 
     There is provided in accordance with the present invention an automatic seatbelt retractor of the type mentioned at the outset in which the child seat locking device has fewer components compared to those of the prior art. 
     Since only a single intermediate element is required for actuation of the securing components by the actuating device, with the solution according to the invention. Not only are the pure material and production costs reduced as the number of components is diminished, but also the assembly costs are reduced, since only a single component has to be assembled in addition to the components already used in the past. 
     In this connection, it should be pointed out that the intermediate element is able to act on an independent securing component for the child seat locking device. It is also possible for the intermediate element to act on an existing securing component of one of the above-mentioned pre-locking devices, in particular the vehicle-sensitive prelocking or pre-blocking device. The securing component can be a pre-blocking pawl that engages in the teeth of a gear wheel that is non-rotatably connected to the winding shaft. 
     For a compact construction of the automatic seatbelt retractor according to the invention, the vehicle-sensitive pre-blocking device can comprise a carrier disc on which the intermediate element and optionally the securing component are rotatably or pivotally mounted. 
     In order to maintain this position, it is in principle sufficient for either the actuating device or the intermediate element to be releasably lockable in the locking position of the pre-locking device or of the child seat locking device, in order to maintain this position. To achieve greater security, however, the actuating device and the intermediate element can also be releasably lockable, independently of one another, in the locking position of the pre-locking device. Catch pins for fixing the actuating device and the intermediate element can be provided on the carrier disc for this purpose. 
     In order to maintain actuation of the intermediate element as simple as possible, it has proven advantageous if the intermediate element comprises at least one cam portion which is in engagement with the actuating device, and one actuating portion which actuates the securing component triggering the pre-locking of the winding shaft. 
     To prevent the pre-locking position from being released prematurely, it is preferably also proposed that the intermediate element have a locking portion for the releasable locking of the intermediate element in its&#39; locking position. 
     In principle, it would be conceivable for the actuating device to be actuated merely by a movement derived from the winding shaft. It is advantageous, however, if the actuating device is a reduction gear that is in direct rotational connection with the winding shaft. 
     Furthermore, the actuating device can again have any construction. It is advantageous if the actuating device contains a tumbling disc which is arranged eccentrically on the winding shaft, is rotatably connected thereto and, as a function of the extracted length of the seatbelt webbing, actuates an activation disc which is rotatably mounted on the winding shaft and is in engagement with the intermediate element. The tumbling disc can have external teeth that roll on internal teeth that are stationary relative to the rotating tumbling disc. 
     For actuating the cam portion of the intermediate element, the activating disc can be provided, on its&#39; outer circumference, with a corresponding control contour that scans the cam portion. 
     To enable the activating disc to actuate the intermediate element when the predetermined length of seatbelt webbing is extracted, the activating disc can have an arcuate recess in which engages a driving pin non-rotatably connected to the tumbling disc. Starting with completely retracted seatbelt webbing, initially the winding shaft, and therefore also the tumbling disc, are set into rotation as the seatbelt webbing is extracted. When a first predetermined extracted length is reached, the driving pin of the tumbling disc comes into contact with one edge of the arcuate recess of the activating disc and entrains the activating disc. The cam portion of the intermediate element therefore slides on the control contour of the outer circumference of the activating disc and, after reaching the second predetermined extracted length, actuates the securing component of the pre-locking device. 
     To avoid premature release of the pre-locking device, the activating disc can also be lockable in the pre-locking position. This catching of the activating disc in the pre-locking position can be achieved by means of a catch lever which is provided at the outer circumference of the activating disc and rests releasably on a catch pin which is stationary in the pre-locking position of the catch lever. This catch pin can in turn be provided on the vehicle-sensitive pre-locking device. To enable the catch lever of the activating disc to be released from the catch pin on release of the pre-locking position, the catch pin can also have a contour that is such that the catch lever is not blocked on the catch pin. 
     To achieve secure locking, it is also advantageous if the securing component is formed by a pawl which is pivotally mounted and which can be pivoted by the intermediate element into the pre-locking position in which the pawl engages in the saw teeth of external teeth of a wheel non-rotatably connected to the winding shaft, the saw teeth pointing in the unwinding direction. 
     For reducing the weight of the automatic seatbelt retractor according to the invention and the production costs, it is of further advantage that the intermediate element is produced from a plastic material. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view of the front face of an automatic seatbelt retractor according to the invention in which the child seat locking device is shown in its&#39; rest position. 
     FIG. 2 is a view similar to FIG. 1 showing the child seat locking device in an intermediate position before attainment of the locking position. 
     FIG. 3 is a view similar to FIG. 1 showing the child seat locking device in the locked position. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Further advantageous developments and an embodiment will be described hereinafter with reference to the accompanying drawings. The terms “top”, “bottom”, “right” and “left” used in conjunction with the description of the embodiments refer to the orientation of the drawings as viewed with a normally legible description of the figures. It should also be noted that identical components are identified by identical reference numerals in the drawings. 
     FIGS. 1 to  3  show an end face of an automatic seatbelt retractor  5  according to the invention with a child seat blocking or child seat locking device. The automatic seatbelt retractor comprises a winding shaft  10  that is made of metal. The winding shaft is mounted in a metal frame of the automatic seatbelt retractor (not shown in detail) that is rigidly connected to the vehicle chassis. Seatbelt webbing (also not shown) of the seatbelt system can be wound onto the winding shaft. In the embodiment shown in FIGS. 1 to  3 , the winding shaft  10  extends substantially horizontally and perpendicularly to the plane of the drawings. For the rotational driving of various components of the seatbelt system, the winding shaft  10  is constructed as a serrated shaft. 
     The shaft end  10   a,  shown in FIGS. 1 to  3 , of the winding shaft  10  passes through a carrier disc  12 , produced from a plastic material, of a vehicle-sensitive pre-blocking device  45 . The carrier disc  12  is arranged concentric with the winding shaft  10  freely rotatably thereon and is secured axially and radially by a plurality of resilient clips  14 , made for example of a plastic material. The clips  14 , one of which is shown in FIGS. 1 to  3 , are arranged along the outer circumference of the carrier disc  12 . The clips are shaped on a casing part made of a plastic material (which is not shown in detail) and is rigidly connected to the metal frame of the automatic seatbelt retractor. 
     The vehicle-sensitive pre-blocking device  45  comprises an inertia body, for example a ball (not shown in detail) which is mounted movably in a casing-like receiver  16  shaped on the lower outer circumference of the carrier disc  12 . A pre-blocking pawl  18  is a securing component that engages the teeth of a gear wheel that is non-rotatably connected to the winding shaft. The inertia body acts on the pre-blocking pawl  18  which is produced from a plastic material and is mounted pivotal about a pivot axis  20  extending parallel to the winding shaft  10  on the receiver  16  of the carrier disc  12 . The pre-blocking pawl  18  is pivoted radially inward by the inertia body during a displacement of the inertia body in the receiver  16  owing to a corresponding deceleration of the motor vehicle. The pre-blocking pawl comes into engagement with a pre-blocking gear wheel  22  that is made of a plastic material and is arranged non-rotatably on the winding shaft  10  behind the carrier disc  12  in the axial direction of the winding shaft  10 . The teeth of the pre-blocking gear wheel  22  are designed in the manner of saw teeth, the saw teeth  22   a  pointing in the unwinding direction of the seatbelt webbing. The pivoting movement of the pre-blocking pawl  18  radially outward is limited by a stop  16   a  located on the receiver  16 . 
     On the side facing the observer, the carrier disc  12  is provided with internal teeth  12   a.  The internal teeth  12   a  are arranged on a carrier ring (not shown in detail) which is formed integrally with the carrier disc  12  and has a diameter which is smaller than the external diameter of the carrier disc. The carrier ring for the internal teeth projects axially from the carrier disc. 
     A tumbling disc  24  made of a plastic material is also provided on the side of the carrier disc  12  facing the observer. The tumbling disc  24  is arranged on the winding shaft  10  eccentrically to the axis A of the winding shaft. For rotational driving by the winding shaft the tumbling disc  24  is provided with a bore-hole  24   a  of which the bore-hole axis (not shown in detail) extends parallel, but eccentrically to the axis of the winding shaft when assembled. With this bore-hole  24   a,  the tumbling disc  24  rests on a hub  10   b  which similarly has an external contour eccentric to the axis A of the winding shaft and is connected non-rotatably to the winding shaft. The tumbling disc  24  has a smaller diameter than the carrier disc  12 . On its&#39; exterior, the tumbling disc  24  has external teeth  24   b  which engage the internal teeth  12   a  of the carrier disc  12  and roll along the internal teeth  12   a  during rotation of the winding shaft  10 . The external teeth  24   b  of the tumbling disc  24  and the internal teeth  12   a  of the carrier disc  12  together form a reduction gear which reduces the rotation of the winding shaft  10  toward the tumbling disc  24 . The thickness of the tumbling disc  24  in the direction of the axis A of the winding shaft  10  roughly corresponds to the thickness of the carrier ring for the internal teeth  12   a,  so that the tumbling disc  24  is received in the carrier ring and ends flush with it. 
     Concentric with the axis A of the winding shaft  10  is an activating disc  26  made of a plastic material that is mounted to rotate freely on the winding shaft. The diameter of the winding shaft  10  is greater than that of the tumbling disc  24  but smaller than that of the carrier disc  12  that is also provided on the side of the tumbling disc  24  facing the observer. The activating disc  26  is secured in its&#39; radial and axial position by a plurality of resilient clips  28  that are shaped integrally on the carrier disc  12  but do not prevent the rotational movement of the activating disc  26 . The activating disc  26  has a circular depression (not shown in detail) which is directed toward the carrier disc  12  and has an internal diameter such that it overlaps the carrier ring for the internal teeth  12   a.  This depression has a depth roughly corresponding to the thickness of the carrier ring for the internal teeth  12   a  in the axial direction. Owing to the axial and radial fixing of the activating disc  26 , the tumbling disc  24  is also secured axially and radially via the circular depression. 
     The activating disc  26  is also provided with an arcuate recess  26   a  extending concentric to the winding shaft  10  over an angle that is smaller than about 180°. As shown in FIGS. 1 to  3  the external radius of the recess  26   a  corresponds roughly to the internal radius of the internal teeth  12   a  of the carrier disc  12 . A driving pin  24   c  formed integrally with the tumbling disc  24  engages in the recess  26   a.    
     An intermediate element  32  made of a plastic material is also mounted rotatably on the side of the carrier disc  12  facing the observer by means of an shaft  30  mounted rigidly on the carrier disc  12 . The shaft  30  is made of a plastic material and extends substantially parallel to the axis A of the winding shaft  10  and is arranged on the carrier disc  12  at the bottom in the region of the vehicle-sensitive pre-blocking device  45 . 
     The intermediate element  32  possesses several functional portions that will be described hereinafter. Thus, the intermediate element  32  comprises a cam portion  32   a,  a catch lever portion  32   b  and an actuating lever portion  32   f.    
     The cam portion  32   a  scans a control contour  34  that is provided on the outer circumference of the activating disc  26  and will be described in more detail hereinafter. The cam portion  32   a  rests on this control contour  34  during the entire actuation of the intermediate element  32  or of the activating disc  26  and has the form of a truncated cone projected into a plane. 
     The catch lever portion  32   b  arranged in a position about 90° in a clockwise direction relative to the cam portion  32   a  is designed as a radially resilient lever. The catch lever portion  32   b  is integrally connected at one end to the intermediate element  32  and initially extends radially outward and then, while maintaining a space  32   c,  in the circumferential direction of the intermediate element  32 . At the free end, the catch lever portion  32   c  is provided with a radially inwardly extending triangular extension  32 d in such a way that the space  32   c  is closed on all sides. The extension  32   d  preferably rests on the outer circumference of the intermediate element  32 . On the projection  32   d,  the catch lever portion  32   b  is provided with a contact contour  32   e  that is directed in the circumferential direction of the intermediate element  32  and with which the catch lever portion  32  rests on a catch pin  36  in a locking position which will be described hereinafter. In the rest position of the intermediate element  32  shown in FIG. 1 the catch lever portion  32   b  comprises the catch pin  36  which is preferably produced from a plastic material and is rigidly mounted on the carrier disc  12  in an orientation substantially parallel to the winding shaft  10 . 
     The actuating lever portion  32   f  of the intermediate element  32  is provided roughly at an angle of 180° opposite the cam portion  32   a.  The actuating lever portion  32   f  is connected integrally to the intermediate element  32  at one end and projects roughly radially outward from the intermediate element. At its&#39; free end, the actuating lever portion  32   f  has an S-shaped contour with a rounded end  32   g.  With this end  32   g,  the actuating lever portion acts on the pre-blocking pawl  18  of the vehicle-sensitive pre-blocking device  45  or on a lever extension  18   a  connected to the pre-blocking pawl. 
     The control contour  34  that is provided on the outer circumference of the activating disc  26  and is scanned by the cam portion  32   a  of the intermediate element  32  has a plurality of control regions  34   a - 34   c.  The first control region  34   a  is formed by the unchanged outer contour of the activating disc  26  and can be described as a control region for the rest position of the intermediate element  32 . The intermediate element is at rest while the cam portion  32   a  of the intermediate element scans this control region  34   a.  The control regions  34   b,    34   c,  i.e. the second and third control regions adjoining the first control region  34   a  in the extraction direction of the seatbelt webbing are formed by the lateral edges of a substantially U-shaped recess  26   b  provided on the activating disc  26 . During the scanning of these control regions  34   b,    34   c  by the cam portion  32   a  of the intermediate element  32 , the intermediate element is pivoted in a clockwise or anticlockwise direction in a manner which will be described hereinafter. 
     In the belt extraction direction, a resiliently designed catch lever  26   c  that directly adjoins the recess  26   b  is provided on the outer circumference of the activating disc  26 . The lateral edge of the recess  26   b  forming the third control region  34   c  is identical to the outer edge of the catch lever  26   c  . The catch lever  26   c  is connected integrally at one end to the activating disc  26 , extends radially outward from there and then, while maintaining a space  38  in the belt extraction direction, in the circumferential direction of the activating disc. At its&#39; free end the catch lever  26   c  is provided with a radially outwardly extending triangular extension  26   d.  With the side of the triangle facing in the belt extraction direction of the extension  26   d,  the catch lever  26   c  rests on a catch pin  40 , made of a plastic material, in a locking position which will be described in more detail hereinafter. The catch pin  40  is mounted on the side of the carrier disc  12  facing the observer in an orientation extending substantially parallel to the winding shaft  10 . The catch lever  26   c  is designed in such a way that it can deflect radially. 
     As already described hereinbefore, FIG. 1 shows the rest position of the child seat locking or pre-blocking device. Starting from this position, the automatic seatbelt retractor according to the invention operates as follows. 
     If the seatbelt webbing is unwound from the winding shaft  10  in a clockwise direction, the pre-blocking gear wheel  22  also rotates in a clockwise direction. Owing to the eccentric arrangement of the tumbling disc  24  relative to the winding shaft  10  and owing to the engagement of the external teeth  24   b  of the tumbling disc  24  with the internal teeth  12   a  of the carrier disc  12 , the tumbling disc  24  is simultaneously set into rotation in a counter clockwise direction. 
     After extraction of a first predetermined length of belt webbing, the driving pin  24   c,  which is non-rotatably connected to the tumbling disc  12  and which engages in the arcuate recess  26   a  of the activating disc  26 , comes into contact with the face end of the recess  26   a  directed in a counter clockwise direction, as shown in FIG.  2 . 
     Since the activating disc  26  is freely rotatable relative to the winding shaft  10 , the activating disc is therefore engaged by the driving pin  24   b  during continued extraction of the seatbelt webbing. The activating disc  26  is therefore rotated in a counter clockwise direction. The cam portion  32   a  scans the control contour  34  at the outer circumference of the activating disc and, after a the extraction of a further predetermined length of the seatbelt webbing, comes into engagement with the recess  26   b,  as shown in FIG.  2 . The cam portion  32   a  comes into contact with the third control region  34   c  of the control contour  34  (see FIG. 2) so that, during further extraction of the seatbelt webbing, the intermediate element  32  begins to pivot or rotate in a clockwise direction. Owing to this pivoting movement, the actuating lever portion  32   f  of the intermediate element  32  again comes into contact with the pre-blocking pawl  18  or the lever extension  18   a  of the vehicle-sensitive pre-blocking device  45 . At the same time, the catch lever portion  32   b  of the intermediate element  32  begins to move past the catch pin  36  by pivoting radially outward. Furthermore, the catch lever  26   c  of the activating disc  26  begins to move past the catch pin  40  mounted rigidly on the carrier disc  12 , while pivoting radially inward owing to contact with the catch pin as shown in FIG.  2 . 
     During further extraction of the seatbelt webbing, the activating disc  26  is rotated further in a counter clockwise direction owing to the engagement of the driving pin  24   b,  so that the actuating lever portion  32   f  of the intermediate element  32  pivots the pre-blocking pawl  18  radially inward via the lever extension  18   a  of the vehicle-sensitive pre-blocking device  45 , so that the pre-blocking device comes into engagement with the teeth  22   a  of the pre-blocking gear wheel  22  as shown in FIG.  3 . At the same time, the catch lever portion  32   b  engages behind the catch pin  36  and the catch lever  26   c  behind the catch pin  40 . The locking position of the child seat locking device is thus achieved. Further extraction of seatbelt webbing is prevented by the engagement of the blocking pawl  18  in the teeth  22   a  of the pre-blocking gear wheel  22 , so that a forward movement of an object, for example a child seat, held by the seatbelt webbing, is avoided. However, the seatbelt webbing can be retracted again at any time as, in this case, the pre-blocking pawl  18  slips over the teeth  22   a.  Premature release of the locking position is prevented by the catch lever portion  32   b  and the catch lever  26   c  contacting the respective catch pin  36 ,  40 . 
     For releasing the locking position, the seatbelt webbing is wound on the winding shaft  10  again by known measures. During this winding, the pawl  18  passes over the teeth  22   a  that are now rotating in a counter clockwise direction. After a predetermined length of seatbelt webbing, the driving pin  24   b  comes into contact with the face end, directed in a clockwise direction, of the recess  26   a  of the activating disc  26 . The activating disc is therefore rotated in a clockwise direction, the catch lever  26   c  disengaging from the catch pin  40  and the catch lever portion  32   b  disengaging from the catch pin  36 . The intermediate element  32  is pivoted in a counter clockwise direction by the second control region  34   b  of the control contour  34 , so that the actuating lever portion  32   f  disengages from the pawl  18 . The pawl pivots from the path of movement of the pre-blocking gear wheel  22  owing to gravity or a spring element (not shown in detail) so that the position shown in FIG. 1 is finally adopted again. 
     In summary the automatic seat belt retractor  5  of the present invention has at least one pre-locking device comprising the pre-blocking pawl  18 , the pre-blocking gear wheel  22 , the activating disc  26  and the intermediate element  32 . That is to say the pre-locking device has an actuating device comprising the tumbling disc  24  and activating disc  26  which actuates at least one securing component in the form of the pre-blocking pawl  18  which is a component of the vehicle-sensitive pre-blocking device  45 . An automatic seatbelt retractor should prevent catching in the otherwise slack seatbelt located inside a vehicle when getting in and out, or loading and unloading, etc. Of course the automatic seatbelt retractor  5  of the present invention contains those well known components that prevent a forward movement of a person secured by the seatbelt when the motor vehicle is subjected to rapid deceleration. Any suitable well known locking device module that prevents unwinding of the seatbelt in such cases may be used in the practice of the present invention to carry this out. To distinguish from further locking devices which may be provided this module is referred to herein and in the appended claims as the main locking means. 
     While certain representative embodiments and details have been presented for the purpose of illustrating the invention, it will be apparent to those skilled in the art that various changes and modifications may be made thereto without departing from the scope of the invention as defined in the following claims.