Patent Publication Number: US-2013241187-A1

Title: Sensor

Description:
The invention relates to a sensor, in particular for triggering a vehicle occupant restraint system, for example for triggering a locking mechanism of a belt retractor. 
     A sensor of this type is known, for example, from German laid-open application DE 10 2004 032 190 A1. This previously known sensor has a lower rolling surface which is defined by a track which runs in a curved manner, extends convexly with respect to the inertia body and is designed without a step. The inertia body can execute a translatory rolling movement on the lower rolling surface. 
     The invention is based on the object of specifying a sensor in which production of noise is avoided or is at least kept as small as possible. 
     This object is achieved according to the invention by a sensor with the features according to patent claim  1 . Advantageous refinements of the sensor according to the invention are specified in dependent claims. 
     Accordingly, the invention provides a sensor with an inertia body which has an oscillating bearing permitting an oscillating movement and, in the event of an acceleration, can be set by inertia into an oscillating movement, and a triggering lever which interacts with the inertia body and is deflected when a predetermined amplitude of oscillation is exceeded. 
     A substantial advantage of the sensor according to the invention is considered that of avoiding annoying rolling noises therein. This is because, in contrast to the previously known sensor described at the beginning, the sensor according to the invention uses an oscillating movement rather than a rolling movement. Rolling noises are therefore avoided. 
     It is considered advantageous if the sensor has a holding element, wherein a first section of the holding element is guided through the oscillating bearing of the inertia body and holds the inertia body pivotably, and a second section of the holding element is guided through a pivot bearing of the triggering lever and holds the triggering lever pivotably. In this refinement, an independent and self-supporting oscillating unit which comprises the holding element, the inertia body and the triggering lever is formed by a single additional component, namely the holding element. 
     The first and the second sections preferably extend parallel, and therefore the pivot axes of the inertia body and those of the triggering lever are preferably also parallel. 
     The first section is preferably designed in such a manner that the inertia body can be pivoted out in all directions. For this purpose, the oscillating bearing of the inertia body and/or that section of the inertia body which is indirectly or directly adjacent to the oscillating bearing can have, for example, conically converging side walls. 
     Particularly preferably, the holding element has a third section which enables fitting of the oscillating unit formed by the holding element, the inertia body and the triggering lever, in particular to or in a housing or to an external vehicle-side support. 
     The third section of the holding element preferably extends perpendicularly to the first and/or to the second section of the holding element. 
     With regard to a high degree of stability and low degree of friction in the oscillating bearing of the inertia body and in the pivot bearing of the triggering lever, it is considered advantageous if the holding element is formed by a multiply bent, single-part rod element, and the first, second and third sections of the holding element are sections of said single-part rod element. The rod element can be formed by a multiply bent, single-part metal wire, preferably made of spring steel. Alternatively, the rod element can be composed of plastic or of a metal and plastic composition, i.e. partially of plastic and partially of metal. 
     The same applies to the oscillating bearing of the inertia body and the pivot bearing of the triggering lever: said bearings are also preferably composed of metal, plastic or a metal and plastic composition. 
     If the sensor has a frame or a housing, it is considered advantageous if the third section of the holding element is hooked into the frame or the housing of the sensor and thereby fixes the position of the oscillating unit formed by the holding element, the inertia body and the triggering lever relative to the frame or relative to the housing. 
     It is also considered advantageous if the inertia body has an upper oscillating section and a lower oscillating section, wherein the upper and the lower oscillating sections are separated from each other by the oscillating bearing. The lower oscillating section is preferably composed of metal, for example iron. 
     The end section of the upper oscillating section may be, for example, plate-shaped or in the shape of a point. In the case of a plate-shaped configuration, a flat, round or conical plate shape is considered advantageous. 
     The shape of the triggering lever is preferably matched to the shape of the upper oscillating section. If the upper oscillating section is in the shape of a point, a dish-shaped triggering lever is considered advantageous, wherein the point of the upper oscillating section is preferably guided in a dish section of the dish-shaped triggering lever. 
     If the end section of the upper oscillating section is plate-shaped, a triggering lever with a cup-shaped section is considered advantageous, wherein the plate-shaped end section of the upper oscillating section is preferably guided in the cup-shaped section of the triggering lever. 
     Furthermore, it is considered advantageous if the mass of the upper oscillating section is smaller than the mass of the lower oscillating section. The mass of the lower oscillating section is preferably at least ten times larger than that of the upper oscillating section. 
     The arrangement of the oscillating bearing, the lever length of the upper and lower oscillating sections and the respective mass of the upper and lower oscillating sections determine the oscillating behavior of the inertia body and the sensitivity of the sensor. The parameters mentioned can be adapted to one another depending on the desired sensitivity of the sensor. 
     In order to avoid unnecessary triggering of the sensor in the event of small vehicle accelerations, it is considered advantageous if the triggering lever has a supporting section which, in the oscillation-free rest position of the inertia body, rests on the upper oscillating section and, by means of gravitational force, opposes an oscillating movement of the inertia body. In this refinement, the supporting section can be caused by gravitational force to press with the mass thereof against the upper oscillating section and can avoid oscillating in the event of only small vehicle accelerations. 
     Alternatively, it is considered advantageous if the triggering lever has an interaction section which, in the oscillation-free rest position of the inertia body, is spaced apart from the upper oscillating section and is brought into contact with the upper oscillating section only in the event of an oscillating movement, the amplitude of which exceeds a predetermined threshold. 
     It is also considered advantageous if the oscillating bearing is formed by a ball and socket joint, since ball and socket joints enable deflection of the inertia body and oscillation in all directions. 
     The invention also relates to an arrangement with a sensor, as described above, and with a vehicle, wherein the holding element is hooked into a vehicle-side support. 
     The invention furthermore relates to a belt retractor with a locking mechanism which is provided with a sensor of the described type. With regard to the advantages of the belt retractor according to the invention, reference is made to the abovementioned advantages of the sensor according to the invention. The belt retractor will produce less noise than previously known belt retractors, since the sensor contained therein operates quietly. 
    
    
     
       The invention is explained in more detail below with reference to exemplary embodiments, in which, by way of example 
         FIG. 1  shows a first exemplary embodiment of a sensor according to the invention in the rest position thereof, 
         FIG. 2  shows the sensor according to  FIG. 1  with a deflected inertia body, 
         FIG. 3  shows the sensor according to  FIGS. 1 and 2  in a three-dimensional view, 
         FIG. 4  shows a second exemplary embodiment of a sensor according to the invention in the rest position thereof, 
         FIG. 5  shows an exemplary embodiment of a sensor according to the invention with a ball element, 
         FIG. 6  shows the sensor according to  FIG. 5  in a three-dimensional illustration, 
         FIG. 7  shows a further exemplary embodiment of a sensor according to the invention with a ball and socket joint, 
         FIGS. 8-9  show an example in more detail of an oscillating bearing for the first exemplary embodiment according to  FIGS. 1 to 3  and the second exemplary embodiment according to  FIG. 4 , and 
         FIG. 10  shows the possibility of a “noiseless position” of the inertia body by means of a form fit. 
     
    
    
     For the sake of clarity, the same reference numbers are always used for identical or comparable components in the figures. 
       FIG. 1  shows a sensor  10  which comprises an inertia body  20 . The inertia body  20  has a lower oscillating section  21  and an upper oscillating section  22 . An oscillating bearing  23  is located between the two oscillating sections  21  and  22  of the inertia body  20 . 
     It can be seen in  FIG. 1  that the end section  24  of the upper oscillating section  22  is configured in a plate-shaped manner and forms an upper, flat or planar supporting surface  25 . 
       FIG. 1  furthermore shows a holding element  30  which is formed by a multiply bent, single-part rod element. A first section  31  of the holding element  30  is guided through the oscillating bearing  23  of the inertia body  20  and, for said oscillating bearing  23 , forms a first shaft about which the inertia body  20  can pivot. 
     A second section  32  of the holding element  30  is guided through a pivot bearing of a triggering lever  40  where it forms a second shaft, namely a pivot shaft for the triggering lever  40 . The triggering lever  40  can pivot about said second shaft. The pivot bearing of the triggering lever  40  is identified in  FIG. 1  by the reference number  41 . 
     The inertia body  20  and the triggering lever  40  are connected to each other by the holding element  30 , and therefore an independent and self-supporting oscillating unit  50  is formed by the three components, namely the inertia body  20 , the holding element  30  and the triggering lever  40 . 
     It can also be seen in  FIG. 1  that the first section  31 —or the first shaft—and the second section  32 —or the second shaft—of the holding element  30  are preferably arranged parallel, and therefore the pivot axis of the inertia body  20  and that of the triggering lever  40  are also parallel. By means of such a parallel arrangement, a particularly compact construction of the oscillating unit  50  can be achieved. 
     The first section  31  of the holding element  30  is preferably arranged in such a manner that the inertia body  20  can execute an oscillating movement in the longitudinal direction of the vehicle. An oscillating movement in the longitudinal direction of the vehicle is identified by a double arrow and the reference symbol P in  FIG. 1 . 
     It can furthermore be seen in  FIG. 1  that the triggering lever  40  is provided with a supporting section  42  by which the triggering lever  40  rests on the upper supporting surface  25  of the end section  24  of the inertia body  20 . The resting of the supporting section  42  is brought about by gravitation, since the triggering lever  40 , because of the gravitational force thereof, will pivot downward about the pivot bearing  41  thereof in the pivoting direction P 1 . 
     In the illustration according to  FIG. 1 , the inertia body  20  is in a rest position, i.e. does not oscillate. The supporting section  42  therefore rests silently on the upper supporting surface  25 , and therefore a locking section  43  of the triggering lever  40  is not in engagement with a locking base  60 . The locking base  60  is part of a locking mechanism (not illustrated in more detail) of a belt retractor (likewise not illustrated in more detail). 
     The effect achieved on account of the dead weight of the triggering lever  40  and on account of the supporting section  42  of the triggering lever  40  pressing onto the upper supporting surface  25  of the inertia body  20  is that an oscillating movement of the inertia body  20  is suppressed, or at least made difficult, at smaller changes in acceleration of the vehicle. An undesirable production of noise is therefore prevented in the event of only small changes in acceleration of the vehicle. If, by contrast, a pronounced change in the acceleration or a jerky movement of the vehicle occurs, the triggering lever  40  will no longer be able to prevent the inertia body  20  from oscillating, and therefore the triggering lever  40  will be deflected and the locking section  43  will engage in the locking base  60 . 
     In addition, a silent position of the inertia body  20  can also be brought about by a form fit, as shown by way of example in  FIG. 10 .  FIG. 10  shows a depression  200  in the inertia body  20 , in which depression the supporting section  42  of the triggering lever  40  can engage with a form fit. 
     Furthermore, a third section  33  of the holding element  30  can be seen in  FIG. 1 . Said third section  33  of the holding element  30  serves to fasten the holding element  30  and therefore the entire oscillating unit  50  to a support or a housing. Such a fastening is explained in more detail in conjunction with  FIGS. 2 and 3 . 
       FIG. 2  shows the oscillating unit  50  according to  FIG. 1  after the third section  33  (cf.  FIG. 1 ) has been pushed into an elongate holding hole in a housing  70  of the sensor  10 . The oscillating unit  50  is therefore hooked in the housing  70  by the third section of the holding element  30 , and the position of the oscillating unit  50  relative to the housing  70  is defined. 
     The third section of the holding element  30  is preferably oriented perpendicularly to the first section  31  and perpendicularly to the second section  32  of the holding element  30  in order to achieve as compact a construction of the sensor  10  as possible. 
     Furthermore, it can be seen in  FIG. 2  that the inertia body  20  is in an oscillating movement and the upper supporting surface  25  of the end section  24  of the inertia body  20  has raised the supporting section  42  of the triggering lever  40 , as a result of which the triggering lever  40  has been pivoted about the pivot bearing  41  thereof. By pivoting of the triggering lever  40  upward in the arrow direction P 2 , the locking section  43  enters into engagement with the locking base  60  such that the locking base  60  is locked, rotation of the locking base is prevented and therefore, for example, extension of a belt strap of a seat belt is stopped. 
       FIG. 3  shows the sensor  10  according to  FIGS. 1 and 2  once again in a three-dimensional view. It is seen that the upper supporting surface  25  of the inertia body  20  has pivoted the supporting section  42  of the triggering lever  40  upward such that the locking section  43  can enter into engagement with the locking base  60 . 
       FIG. 4  shows a second exemplary embodiment of a sensor  10 . An inertia body  20 , a holding element  30  and a triggering lever  40 , which together form an oscillating unit  50 , are seen. In the exemplary embodiment according to  FIG. 4 , the triggering lever  40  does not have a supporting section which would rest on the upper supporting surface  25  of the inertia body  20  in the rest state. Instead, an interaction section  45  is provided, said interaction section entering into contact with the upper supporting surface  25  only in the event of an oscillating movement of the inertia body  20 . In order to achieve a spatial separation and a distance “a” between the triggering lever  40  and between the interaction section  45  and the upper supporting surface  25 , the sensor  10  is provided with a stop  90  on which the locking section  43  of the triggering lever  40  rests in the rest state. In the rest state, i.e. if there is no oscillating movement of the inertia body  20 , the triggering lever  40  and the inertia body  20  are therefore separated from each other such that there is neither friction between the triggering lever  40  and inertia body  20  nor production of noise. 
     If, on account of an abrupt change in the acceleration of the vehicle, an oscillating movement of the inertia body  20  then occurs, at a sufficient amplitude of the oscillating movement the upper supporting surface  25  of the inertia body  20  will strike against the interaction section  45  of the triggering lever  40  and pivot the triggering lever upward in the arrow direction P 2  such that the locking section  43  of the triggering lever  40  can engage in the locking base  60 . 
       FIGS. 8 and 9  show an exemplary embodiment of the oscillating bearing  23  of the sensor  10  according to  FIGS. 1 to 3  and of the oscillating bearing of the sensor  10  according to  FIG. 4  in more detail. It can be seen that the inertia body  20  can pivot in all directions. In the exemplary embodiment according to  FIGS. 8 and 9 , the oscillating bearing  23  has side walls  23   a  converging conically. 
       FIG. 5  shows a third exemplary embodiment of a sensor  10 . The sensor  10  has an inertia body  20  with a lower oscillating section  21  and an upper oscillating section  22 . The two oscillating sections  21  and  22  are separated from each other by a spherical section  28  of the inertia body  20 . The spherical section  28  together with an associated bearing  100  forms a ball and socket joint  110  which supports the inertia body  20  pivotably. 
     It is furthermore seen in  FIG. 5  that the upper oscillating section  22  is in the shape of a point and has an upper point  120 . In the event of an oscillating movement of the inertia body  20 , the upper point  120  will correspondingly oscillate at the same time. 
       FIG. 6  shows the sensor according to  FIG. 5  in a three-dimensional illustration. It is seen that the sensor  10  has a dish-shaped triggering lever  40  which is provided with a dish section  48 . The shape of the dish section  48  is matched to the shape of the point  120  of the inertia body  20  such that, in the event of an oscillating movement of the inertia body  20 , the dish-shaped triggering lever  40  can be deflected and the locking section  43  can be brought into engagement with the locking base  60 . 
       FIG. 7  shows a fourth exemplary embodiment of a sensor  10 . Also in this exemplary embodiment, the inertia body  20  is provided with a spherical section  28  which is held by a bearing  100 . The end section  24  of the upper oscillating section is configured in a plate-shaped manner. The shape of the triggering lever  40  is matched to the plate shape of the end section  24 : the triggering lever  40  thus has a cup-shaped section  49  in which the plate-shaped end section  24  engages. 
     If, in the event of a change in the acceleration of the vehicle, an oscillating movement of the inertia body  20  occurs, the resultant oscillating movement of the plate-shaped end section  24  will lead to a deflection of the triggering lever  40  such that a locking section  43  of the triggering lever  40  can engage in a locking base  60 . 
     It can be seen in  FIG. 7  that the cup-shaped section of the triggering lever  40  has an at least approximately planar base surface which, in the rest state of the inertia body  20 , is oriented at an angle relative to the upper supporting surface  25  of the inertia body  20 . 
     LIST OF DESIGNATIONS 
       10  sensor 
       20  inertia body 
       21  lower oscillating section 
       22  upper oscillating section 
       23  oscillating bearing 
       23   a  side walls 
       24  end section 
       25  supporting surface 
       28  spherical section 
       30  holding element 
       31  first section 
       32  second section 
       33  third section 
       40  triggering lever 
       41  pivot bearing 
       42  supporting section 
       43  locking section 
       45  interaction section 
       48  dish section 
       49  cup-shaped section 
       50  oscillating unit 
       60  locking base 
       70  housing 
       90  stop 
       100  bearing 
       110  ball and socket joint 
       120  point 
     a distance 
     P oscillating movement 
     P 1  pivoting direction 
     P 2  arrow direction