Abstract:
Disclosed is a support ( 10 ) for a sensor element ( 11 ). The support ( 10 ) is for potting and manufacturing a rotational speed sensor. The support ( 10 ) comprises an at least partially hollow body for accommodating electric contacts and a potting compound. According to the invention, a cover ( 25 ) is provided for covering and filling a recess defined by the at least partially hollow body.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is the National Stage of International Application No. PCT/EP2015/001634, filed on 7 Aug. 2015, which claims priority to and all advantages of German Patent Application No. 10 2014 013 356.7, filed on 8 Sep. 2014, the content of which is hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention generally relates to a support and, more specifically, to a support for a sensor element, an assembly including the same, and to a rotational speed sensor. 
       BACKGROUND OF THE INVENTION 
       [0003]    Active rotational-speed sensors for motor vehicles or other applications may exhibit a Hall sensor by way of sensor element. Such a Hall sensor is also designated as a Hall IC and interacts with a pulse wheel. Depending on the type of construction, the pulse wheel is a magnetic multipole wheel or a toothed wheel that is not magnetized. In the latter case, a permanent magnet is assigned to the Hall sensor. An active wheel-speed sensor with Hall sensor element with permanent magnet and punched ring by way of pulse transmitter is disclosed in WO 2011/012399 A1. 
         [0004]    The operation of the sensor element can easily be impaired by dust, dirt and moisture. The sensor element may therefore have been completely encapsulated by an injection-molding compound, see DE 10 2009 008 457 A1. 
         [0005]    In the course of encapsulation a defined position of the sensor element and, where appropriate, of the permanent magnet has to be guaranteed. For this purpose it is known to hold the sensor element or the permanent magnet in a support, see KR 20110057455 (A). 
         [0006]    The sensor element exhibits electrical contacts which in the region of the support have to be connected to contact wires of electrical leads. A connecting region of electrical contacts and contact wires has to be accessible for the connection of the same. The support exhibits apertures or recesses for this purpose. 
         [0007]    A relatively large amount of injection-molding compound has to be supplied through the apertures and recesses in the course of encapsulating the support and the sensor element. Associated with this are a high influx of thermal energy and also the risk of impairments of the components that are present in the course of encapsulation and/or in the course of the subsequent cooling of the injection-molding compound. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention provides a support that is particularly well suited for encapsulation with an injection-molding compound. 
         [0009]    The support according to the invention comprises an at least partially hollow body for receiving electric contacts and a potting compound. The support further comprises a cover for covering and filling out a recess defined by the body. The existing recess of the body is at least partially filled out by the cover. By virtue of this measure, the injection-molding compound to be injected into the support altogether and the resulting thermal loading can be distinctly reduced. The cover may also have been adapted to the external shape of the support, so that the external surface of the support becomes more uniform by virtue of the cover than without the cover. Greatly differing cross sections and thicknesses of the injection-molding compound are avoided by virtue of the cover. 
         [0010]    In certain embodiments, the body exhibits a substantially cylindrical basic shape. At the same time, the cover can be inserted into the recess along a part of a radially exterior side. In this way, the cover complements the cylindrical basic shape and contributes to filling it out. 
         [0011]    In these or other embodiments, the body is of elongated design, and that the recess is located along a part of a longitudinal side. In particular, the cover and the recess each exhibit a length that corresponds to approximately one half of the length of the body. In this way, the recess has been dimensioned sufficiently to enable access to the electrical contacts during production. The cover fills out the contour of the recess—also in the direction toward the contacts—as far as possible. 
         [0012]    The depth of the recess typically corresponds to approximately one half of the thickness of the body. The same typically applies to the cover, though the latter may also exhibit a somewhat smaller depth. 
         [0013]    In certain embodiments, the cover exhibits an external surface, and that the body defines an outlet aperture for the potting compound, the outlet aperture of the body and the external surface of the cover being designed and arranged relative to one another in such a way that the potting compound emerging from the outlet aperture presses against the external surface of the cover. In the course of the supply of the injection-molding compound into the support, some of it emerges from the outlet aperture, presses against the external surface, and in this way holds the cover securely in its closed position. As a result, it is guaranteed that the cover will not be lifted by the flowing injection-molding compound. 
         [0014]    In various embodiments, the external surface extends, at least partially, obliquely with respect to a longitudinal extent of the body or of the cover. Opposite the external surface the cover may exhibit a detent element which holds the cover securely. The detent element then acts at one end of the cover, and the injection-molding compound applied to the external surface acts at the other end. 
         [0015]    In certain embodiments, the body is of elongated design and in the region of a front side exhibits an inlet aperture for the potting compound. The inlet aperture is typically connected to the aforementioned outlet aperture or is arranged adjacent thereto. The outlet aperture has then also been provided close to the front side. 
         [0016]    In various embodiments, the cover and/or the body exhibit(s) surfaces with elevations directed radially outward. In this case it is typically a question of burls, spigots or lugs for centering in a mold in the course of potting. At the same time, the elevations have the effect of spacers from insides of the mold. As a result, after the potting all the external surfaces of the body and the cover have been covered with the potting compound, where appropriate apart from front faces or external surfaces of the elevations. 
         [0017]    In certain embodiments, the body exhibits at least one aperture for access to the electrical contacts, in particular to the contacts to be connected to one another. The aperture is typically an aperture situated opposite the recess of the body. Without a cover, the contacts are accessible from two sides, namely through the aperture, on the one side, and through the recess, on the other side. 
         [0018]    In various embodiments, the body is of elongated design. At the same time, a receptacle for a sensor element has been provided in the region of a front side. Moreover, a partition may have been provided between the receptacle and the body, in particular with a passage for the potting compound. By virtue of the partition, the thermal loading of the sensor element in the course of potting is reduced. 
         [0019]    The invention also provides an assembly, in particular for producing a rotational-speed sensor, with at least one sensor element and with a support according to the invention. The support and the sensor element have typically already been potted together. 
         [0020]    Finally, the invention also provides a rotational-speed sensor, with a support according to the invention and with a sensor element, the support and the sensor element having been potted together. A rotational-speed sensor designed in such a manner can be produced inexpensively and is reliable in application. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    Further features of the invention will become apparent from the description in other respects, and from the claims. Advantageous exemplary embodiments of the invention will be elucidated in more detail in the following on the basis of drawings, in which: 
           [0022]      FIG. 1  shows a representation of various stages in the production of a rotational-speed sensor, 
           [0023]      FIG. 2  shows a support with raised cover in a side view; 
           [0024]      FIG. 3  shows the support with cover according to  FIG. 2  in a front view, 
           [0025]      FIG. 4  shows the support with cover according to  FIG. 2  in perspective representation, 
           [0026]      FIG. 5  shows the support with cover according to  FIG. 2  in a radial top view, 
           [0027]      FIG. 6  shows the support with attached cover in a side view, 
           [0028]      FIG. 7  shows the support with attached cover according to  FIG. 6  in a radial top view, 
           [0029]      FIG. 8  shows the support with cover according to  FIG. 6  in perspective representation, 
           [0030]      FIG. 9  shows a support with raised cover in side view, similar to  FIG. 2  but with differently configured cover, 
           [0031]      FIG. 10  shows the finished rotational-speed sensor in a representation analogous to  FIG. 9 , namely with cover sketched radially outside and with representation of the direction of flow of the material in the course of hypothetical potting of the support without cover, and 
           [0032]      FIG. 11  shows a representation corresponding to  FIG. 10 , but with inserted cover, with representation of the direction of flow of the material in the course of potting of the support. 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    In  FIG. 1 , various components and manufacturing stages of a complete rotational-speed sensor can be discerned. Inside the rotational-speed sensor, a support  10  with sensor element  11  and connecting lead  12  has been provided. An external casing of the rotational-speed sensor is formed by a metal cylinder  13  which is open on one side. 
         [0034]    Above the stated parts  10 ,  11  a further cylindrical part  14  is visible. It is a question of the support  10  at a certain stage of manufacture, namely surrounded by the potting compound and after removal from an injection mold. The metal cylinder  13  is pushed over part  14 , so that a circumferential collar  15  of the metal cylinder  13  extends over a circumferential shoulder  16  of part  14 . For the purpose of sealing, an O-ring (not shown) has been provided under the collar  15 . 
         [0035]    The connecting lead  12  consists here of at least three different portions, namely a cable  17 , two conductors  18  and two conductor contacts  19 . Part  16  exhibits at one end an elbow  20 , into which the connecting lead  12  has been potted. Part  14 , however, has been drawn in  FIG. 1  without the connecting lead  12 . In fact, only the cable  17  protrudes upward out of the elbow  20 . 
         [0036]    The sensor element  11  has been provided with sensor contacts  21  which have been electrically connected in the support  10  to the conductor contacts  19 . 
         [0037]    The support  10  comprises a partially hollow body and exhibits an elongated, cylindrical basic shape, with a front region  22  for receiving the sensor element  11 , with an opposing front region  23  for entry of the connecting lead  12 , with a central region  24  of reduced thickness, and with a cover  25  abutting the central region  24 . The cover compensates for the smaller thickness of the central region  24  and is situated, just like the central region  24 , between the two front regions  22 ,  23 . The combination of cover  25  and central region  24  exhibits a somewhat smaller cross section or outer perimeter than the two front regions  22 ,  23 . 
         [0038]      FIG. 3  shows the front view of front region  22  for receiving the sensor element  11 . 
         [0039]    The central region  24  is shown in greater detail in  FIG. 4 . Discernible are a partly solid region  26 , adjacent to front region  23  and with two parallel channels extending in the longitudinal direction, the apertures  27  of which are visible in  FIG. 4 . The conductors  18  are guided in the channels. 
         [0040]    Between region  26  and front region  22  the central region  24  exhibits, in addition, a window region  28 , with two windows  29  extending parallel to one another. The stated channels with the apertures  27  lead laterally into the windows  29 . The windows  29  are permeable at right angles to the longitudinal direction or, to be more exact, in the radial direction of the support  24 . In the region of the windows  29 , contacts  19  are connected to contacts  21  in overlapping manner. By virtue of the arrangement of the windows  29 , it is possible to machine the contacts  19 ,  21  inserted into the support  24  for the purpose of connecting the contacts, for example to solder them together, in the view of  FIG. 2  from above and from below. 
         [0041]    The central section  24  exhibits in a longitudinally-directed plane a circumferential frame  30  on which the cover  25  comes to be situated in a closed position. For this purpose the cover  25  may exhibit on its underside a circumferential shoulder  31 —see, in particular,  FIG. 2 . The shoulder  31  is bounded inwardly by a projection  32  which can be inserted into the frame  30  in fitting manner. As a result, the cover  25  has been positioned unambiguously on the support  24 . 
         [0042]    On its front sides  33 ,  34  the cover  25  may exhibit detent elements which interact with detent elements, not shown, of the front regions  22 ,  23  of the support  24 . 
         [0043]    Channels, not shown, for the transmission of the potting compound may have been provided in the cover  25 . Discernible in  FIG. 4  are a cover-side outlet aperture  35  in front region  23  and an outlet aperture  36  on front side  33 . Outlet apertures directed toward the support  24  may also have been provided on the cover  25 , in particular so as to correspond to the windows  29 . 
         [0044]    On its front regions  22 ,  23  the support  10  exhibits elevations directed radially outward, namely burls  37 ,  38 . In the present exemplary embodiment, each front region  22 ,  23  exhibits circumferentially four burls  37  and  38 , respectively. Analogously thereto, the cover  25  has been provided on its upper side with burls  39  which follow one another in the longitudinal direction of the support  10 . 
         [0045]    The burls  37 ,  38 ,  39  bring about a centering of the support  10  in the course of the potting in the mold which is not shown. At the same time, it is ensured by the burls  39  that the cover  25  does not lift off in the course of potting. 
         [0046]    Front region  23  for the connecting lead  12  is bipartite. A frontal end  40  exhibits a somewhat larger diameter than a portion  41  directed toward the central region  24 ; see, in particular,  FIGS. 6 and 7 . The end  40  exhibits on its front side  42  at the edge a depression  43  for entry of the connecting lead  12 . In addition, apertures, not shown, may have been provided for the entry of the potting compound, in particular so as to correspond to the outlet aperture  35 . 
         [0047]    Front region  22  is substantially of pot-like design with a thick circumferential wall  44 , with a circumferential front face  45  of the wall  44 , and with a partition  46  with respect to the central region  24 ; see  FIG. 3 . The partition  46  may have been provided with an aperture  47  for the  2   5  passage of the potting compound, and with channel apertures  48  for the passage of contacts  21 . 
         [0048]    The circumferential wall  44  is interrupted by a resilient detent element  49 —see, in particular,  FIG. 7 —with which the sensor element  11  inserted into front region  22  is held there. 
         [0049]    Elevations  50  may have been provided on the circumferential front face  45 . The elevations act, like the burls  37 ,  38 ,  39 , in centering manner and/or for the purpose of guiding the potting compound in the course of potting. 
         [0050]      FIGS. 9 to 11  show a modified embodiment of the support  10  and the cover  25 . The cover  25  here has been provided with an oblique external surface  51  which is subjected to incident flow of the potting material in the course of potting (in the injection-molding process); see, in particular,  FIG. 11 . With respect to a longitudinal axis of the support  10  the oblique external surface  51  exhibits an angle of approximately 30 degrees and faces toward the outlet aperture  35 . The potted support  10  in the metal cylinder  13  is shown in  FIG. 11 . A thick arrow  52  points in the longitudinal direction toward front side  42  and indicates from which direction and at which point the potting compound was injected into the mold, which is not represented in any detail. The many small black arrows  53  illustrate the path of the potting compound through front region  23 . A long, narrow arrow  54  points from the oblique external surface  51  to the central region  24  and illustrates the location and direction of the force acting on the cover  25  by virtue of the flowing potting compound. 
         [0051]      FIG. 10  shows, purely hypothetically for the purpose of clarification on the basis of arrows  53 , the flow of the potting compound if no cover were attached. In this case, the potting compound would arrive directly through the windows  29  at a connecting region  55  of the contacts  19 ,  21  and would subject the contacts to a relatively high pressure from above, with higher pressure than from below. The connection can be impaired thereby. In the connecting region  55  a low pressure and a low rate of flow are striven for. This too is obtained by virtue of the cover  25  and the configuration thereof described with reference to the figures.