Abstract:
A sensor device for detecting rotation, having a position transmitter with a shaft element having first and second shaft ends. The rotation to be detected is introduced via the first shaft end. The shaft element contains a magnet element at the second shaft end, a sensor element for detecting the rotation of the magnet element, and a housing part with at least two sections are separated from each other. The shaft element of the position transmitter is mounted on the first section, and the sensor element is arranged in the second section. The housing part and the shaft element each have a first bearing portion shaped so as to taper towards the shaft end in the region of the second shaft end, the shaft element supported on the housing part on the first bearing portion in order to support the position transmitter on the housing part.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is the U.S. National Phase Application of PCT/EP2015/072035, filed Sep. 24, 2015, which claims priority to German Patent Application No. 10 2014 219 390.7, filed Sep. 25, 2014, the contents of such applications being incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a sensor device for sensing a rotation. 
       BACKGROUND OF THE INVENTION 
       [0003]    A ride-height sensor is known from DE 10 2007 034 099 A1, which is incorporated by reference. The ride-height sensor shown in said document has a lever arm which is connected at a first end to a moving element. At the other end, the lever arm is connected to a shaft, wherein the shaft has a signal-emitting element such that the rotation of the lever arm is able to be determined via the movement of the shaft. The shaft is fitted within a housing. The shaft  14  circumferentially has, at its end remote from the lever arm, a rotationally symmetrical collar having a shoulder. The collar is located in a corresponding collar receiving region of the bearing chamber, the diameter of which is greater than the diameter of the rest of the bearing chamber. The solution shown in said document has the drawback that the shaft cannot be formed integrally with the lever element. 
         [0004]    DE 10 2011 118 775 B3, which is incorporated by reference, shows a similar ride-height sensor, wherein, in order to be mounted, the shaft has a portion in the form of a spherical cap. Although it is possible, by means of the portion in the form of a spherical cap, to introduce the shaft into the housing part and latch it in place therein, it is relatively complicated to produce the portion in the form of a spherical cap with a precise fit. 
       SUMMARY OF THE INVENTION 
       [0005]    Therefore, an aspect of the invention is a sensor device having a shaft element that is able to be produced easily and is able to be incorporated into a housing of the sensor device with little effort. 
         [0006]    An aspect of the invention is based on the basic idea of using the portion that narrows toward the shaft end to make it easy to produce radial and axial mounting of the shaft element of the position encoder. The narrowing of the bearing portion can be realized by means of a portion that narrows continuously or is shaped in the form of a cone. However, it is also conceivable to realize the narrowing in a stepped manner. The latter variant can be realized for example by means of a blind hole. In any case, the shaft element bears on the housing part in the region of the bearing portion such that the shaft element is supported both in the radial direction and in an axial direction. In the case of the stepped configuration of the bearing portion, at least one contact face oriented transversely to the longitudinal axis of the shaft and an adjoining contact face, extending radially about the longitudinal axis, between the shaft element and the housing part are produced. 
         [0007]    The arrangement of the narrowing portion at the second shaft end, where a magnet element is also arranged as signal encoder, has the advantage that this positionally sensitive region is mounted directly and thus remains in an accurate position. As a result, even with one bearing portion, sufficient positional accuracy of the shaft element can be ensured. As a result of the shape narrowing toward the shaft end, the shaft element can also be inserted into the interior of the housing part from the outside and/or from above, such that it is possible to form the shaft element integrally with the lever element and at the same time to mount it in one step inside the housing part, wherein further adjustment steps thereof are not taken into consideration. This structure also simplifies the separation of the two portions of the housing part and thus also the separation of the sensor element from external influences which can exist inside the first portion of the housing part. 
         [0008]    Within the meaning of an aspect of the invention, the term bearing portion is used to describe a portion or region in which the shaft element or housing part is shaped in accordance with the invention in order to mount the shaft element on the housing part. Therefore, the bearing portions on the shaft element and on the housing part are oriented with respect to one another such that they are in contact with one another. As a result of the direct contact between the housing part and the shaft element in the region of the bearing portion, friction occurs between the two parts upon rotation of the shaft element. However, this friction is acceptable to a certain extent for many applications. In order to avoid excessive friction between the housing part and the shaft element, however, there is no contact between the two parts away from the bearing portion. Thus, there is an air gap between the shaft element and the housing part away from the bearing portion. In this way, the bearing portions can also be oriented with respect to one another in order to set the degree or intensity of friction as desired by way of production measures or construction measures. 
         [0009]    The housing part may be configured as a part that is separate from the housing of the sensor device and can be connected to the housing by overmolding or can be integrated into the housing. Alternatively, the housing part represents a region or portion of an integrally formed housing. The first and second portions of the housing part are preferably separated from one another such that it is not possible for moisture in the form of water, oil or comparable media to flow through from one portion to the other, for example in order to protect the sensor element therefrom. 
         [0010]    The sensor device according to an aspect of the invention is advantageously developed in that the first bearing portion is shaped in a manner narrowing in a stepped manner. The stepped embodiment of the bearing portion has the advantage of easy producibility. Furthermore, this embodiment has the advantage that the region toward the second shaft end can be sealed off by means of the contact faces between the shaft element and the housing part. In this way, the region between the magnet element and the housing can be effectively protected from dirt and moisture which could possibly negatively affect the action of the sensor element. Furthermore, the stepped embodiment of the bearing portion allows the axial spacing between the magnet element and the sensor element to be set as precisely as possible. 
         [0011]    The sensor device according to an aspect of the invention is advantageously developed in that the first bearing portion has a substantially horizontally extending contact face and a substantially vertically extending contact face, which immediately adjoin one another. By means of the contact faces oriented substantially orthogonally to one another, it is particularly easy to mount the shaft element. 
         [0012]    The sensor device according to an aspect of the invention is advantageously developed in that the housing part and the shaft element are produced with a precise fit in the region of the first bearing portion. As a result of the precision fit, high positional accuracy and good sealing off of the region of the second shaft end are achieved. 
         [0013]    The sensor device according to an aspect of the invention is advantageously developed in that the position of the horizontal contact faces is produced with a precise fit. In this way, the axial spacing between the magnet element and the sensor element can be set particularly precisely. In this connection, a precise fit is therefore intended to mean that the tolerance range for producing or machining the region or portion in question with respect to other regions is significantly smaller, in order to achieve greater precision of the dimensions and relative positions. 
         [0014]    The sensor device according to an aspect of the invention is advantageously developed in that the second shaft end is not in contact with the housing part. Although the spacing between the magnet element and the sensor element is increased as a result, friction upon rotation of the shaft element is avoided as a result of a small air gap between the housing part and the second shaft end, this allowing smoother rotation of the shaft element overall. 
         [0015]    The sensor device according to an aspect of the invention is advantageously developed in that the housing part and the shaft element each have, between the first shaft end and the first bearing portion, a second bearing portion for radially mounting the shaft element. According to this embodiment, the shaft element is mounted only by the two bearing portions and is also only in contact with the housing part in the region of the bearing portions. As a result of the further radial mounting at the second bearing portion, tilting of the shaft element about the longitudinal axis is effectively prevented. In this way, it is possible to keep the shaft element in a particularly accurate position relative to the housing part and thus also to the sensor part. The shaft element and the housing part are advantageously produced with a precise fit with respect to one another in the region of the second bearing portion. Although further radial bearing portions are also conceivable, the combination of the first and second bearing portions provides the ideal solution for cost-effective and secure mounting of the shaft element. 
         [0016]    The sensor device according to an aspect of the invention is advantageously developed in that the shaft element is formed, in the second bearing portion, with a protrusion having a contact face, extending substantially parallel to the longitudinal axis of the shaft element, with respect to the housing part. In this way, it is particularly easy to realize the mounting on the second bearing portion. 
         [0017]    The sensor device according to an aspect of the invention is advantageously developed in that the surface of the housing part or shaft element has a lubricant at least in the region of one bearing portion. In this way, the friction between the shaft element and the housing part can be effectively reduced. For example, the contact face on the shaft element or on the housing part could be provided with a lubricating layer, for example PTFE, applied to the surface. However, it is also conceivable to form the shaft element or the housing part itself by means of a material that is as low-friction as possible, at least in the region of one bearing portion. 
         [0018]    The sensor device according to an aspect of the invention is advantageously developed in that the housing part has contact faces formed in a segmented manner in the region of at least one bearing portion, wherein the contact faces are separated from one another by means of grooves or recesses. The segmented contact faces, or contact faces that are configured in a segmented manner, moreover ensure the mounting of the shaft element on the housing part. By means of the clearances between the contact faces, the size of the overall contact face is reduced as a whole, such that the friction between the shaft element and the housing part is reduced. Furthermore, the clearances or grooves have the advantage that dirt particles or the like do not collect in the region of the contact faces but are conveyed into the grooves by the rotation of the shaft element. The grooves arranged between the contact faces can also be used as stores for lubricant. 
         [0019]    The sensor device according to an aspect of the invention is advantageously developed in that the grooves or recesses are provided to receive a lubricant. The bearing portions are provided with a lubricant before the shaft element is mounted in the housing part. By way of the grooves, a greater quantity of lubricant can be introduced into the bearing portions. 
         [0020]    The sensor device according to an aspect of the invention is advantageously developed in that the fit in the region of the bearing portion is designed so as to seal off the region of the second shaft end. 
         [0021]    The sensor device according to an aspect of the invention is advantageously developed in that the sensor element has a chip, wherein the housing part has, in the first portion, a recess for receiving the chip or an electronic component for sensing the magnetic field of the magnet element, wherein the position of the recess is aligned precisely with the position of the shaft element. This ensures that the sensor element also maintains the relative position with respect to the magnet element throughout the service life of the sensor device. 
         [0022]    The sensor device according to an aspect of the invention is advantageously developed in that the position encoder has a lever element which is arranged at the first shaft end and is formed integrally with the shaft element, wherein, in the region between the shaft element and the lever element, a recess is formed, via which the position encoder is able to be latched in place in the housing part. In this way, the position encoder can be mounted with particularly little effort. The latching of the position encoder in place on the housing part in the connecting region between the lever element and the shaft element furthermore has the advantage that the penetration of dirt and moisture into the housing part can be prevented in part. Depending on the application, this region can also be provided with an additional seal. 
         [0023]    An aspect of the invention also covers using the sensor device as a ride-height sensor. The abovementioned embodiments are particularly well suited in particular for use in a ride-height sensor, since in this case the rotational speeds and rotary strokes are relatively small and thus contact mounting between the shaft element and the housing part is durable even over a relatively long service life. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    The invention is described in more detail in the following text by way of figures and an exemplary embodiment. In the figures: 
           [0025]      FIG. 1  shows a perspective view in partial section of a first exemplary embodiment of the sensor device according to the invention, 
           [0026]      FIG. 2  shows a perspective view in partial section of parts of the sensor device, 
           [0027]      FIG. 3  shows a sectional view of a subregion of the parts shown in  FIG. 2 , 
           [0028]      FIG. 4  shows a perspective view of the underside of the housing part with a sensor element, 
           [0029]      FIG. 5  shows a perspective view in partial section of the housing part of a second exemplary embodiment, and 
           [0030]      FIG. 6  shows a cross-sectional view of the housing part from  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0031]    For the sake of clarity, some reference signs have been omitted from some figures. These missing reference signs should be mentally added from the other figures. Therefore, the description is also likewise applicable to the elements that are sometimes not provided with reference signs. 
         [0032]      FIG. 1  shows a sensor device  1  for sensing a rotation, having a position encoder  2 , a sensor element  5 , and a housing part  70  integrated into a housing  7 . The sensor device  1  is used as a ride-height sensor, in particular for determining the height of a motor vehicle body. 
         [0033]    To this end, the sensor device  1  is connected to a height adjusting device of the motor vehicle, for example a strut. When the height of the vehicle body is adjusted, the height of the adjustment can be determined by means of the sensor device  1 . In this application, the sensor device is exposed to dirt and water since it is arranged in the region of the wheels. 
         [0034]    Therefore, it is necessary to protect the functionally essential parts of the sensor device  1  from external influences. This relates in particular to the electronics. In particular with regard to a long service life, it is essential for the interior of the sensor device  1  to remain substantially dry. 
         [0035]    The position encoder  2  has a shaft element  20  with a first and a second shaft end  21 ,  22 . The position encoder  2  furthermore has a lever element  40  which is arranged at the first shaft end  21 . The shaft element  20  and the lever element  40  are integrally formed. The lever element  40  and the shaft element  20  are preferably manufactured as an injection-molded part. At the free end, the lever element  40  has a bore  41  (see  FIG. 2 ) via which the shaft element  40  is able to be coupled in a form-fitting manner to a moving element, for example a strut. The shaft element  20  is arranged at the opposite end of the lever element  40  from the free end. In this way, the movement of the moving element can be transmitted to the shaft element  20  via the lever element  40 , whereupon the shaft element  20  rotates. 
         [0036]    The lever element  40  is configured in the form of a flat bar. The upper and lower sides  43 ,  44  of the shaft element  40  are formed in a substantially planar manner. The first embodiment, shown in  FIGS. 1-3 , has a plurality of recesses  45  on the upper and lower sides  43 ,  44  of the lever element  40 , in order to achieve a uniform wall thickness of the lever element  40 . The two ends of the lever element are rounded. Formed at the second end of the lever element is a collar  46  via which the lever element and the shaft element  20  are able to be latched in place on the housing part  70 . In this case, the collar  46  has an outer lip  46   a  and an inner lip  46   b  which are connected together via the upper side or top side  43  of the shaft element and in this way form a U-shaped collar. In the region of the upper edge  72  of the housing part  70 , the inner lip  46   b  has a small protrusion  47  (see for example  FIG. 3 ) in order to latch the lever element  40  and the shaft element  20  in place on the housing part  70 . The shaft element  20  and the collar  46  are configured such that the lever element  40  does not sit on the upper edge  72  of the housing part, but rather a small air gap arises between the collar in the transition region of the lips  46   a,    46   b  and the top edge  72  of the housing part. 
         [0037]    The shaft element  20  is oriented perpendicularly to the lever element  40 . It extends away from the underside  44  of the lever element, wherein the transition from the inner lip  46   b  to the shaft element  20  is smooth. In a non-integral embodiment of the shaft element  20  and of the lever element  40 , the connection between the two elements could be realized by means of a plug connection or the like. The shaft element  20  is formed in a cylindrical or slightly conical manner and has a shape that narrows slightly toward the shaft end  22 . The radius of the shaft element  20  is selected such that there is no contact between the shaft element  20  and the inner side  74  of the housing part  70 . Rather, the shaft element  20  has two bearing portions  24 ,  29 , via which the shaft element  20  bears on the inner side  74  of the housing part  70  and thus mounts the shaft element  20 , but also the lever element  40  indirectly in the radial and axial direction on the housing part  70 , or housing  7 . 
         [0038]    The first bearing portion  24  is arranged approximately in the middle between the second shaft end  22  and the protrusion  47  on the inner lip  46   b.  The first bearing portion  24  mounts the shaft element  20  in the radial direction, this being illustrated in  FIG. 3  by the arrows  25 . To this end, the first bearing portion  24  has a protrusion that protrudes from the lateral surface of the shaft element  20  and has a contact face  26  extending parallel to the inner side  74  of the housing part  70 . Provided between the contact face  26  and the lateral surface of the shaft element  20  are continuously extending transition surfaces, in order to prevent tilting or the like. 
         [0039]    The second bearing portion  29  is arranged in a manner spaced apart from the first bearing portion  24  in the axial direction and is located in the region of the second shaft end  22  of the shaft element  20 . The second bearing portion  29  has a portion that is shaped in a manner narrowing toward the shaft end. In this case, the shaft element  20  bears on the housing part. In the exemplary embodiment, the second bearing portion is configured as a shaft ledge which interacts with a corresponding blind hole in the housing part  70  in order to mount the shaft element  20  both in the radial and in an axial direction, as is illustrated in  FIG. 3  by the arrows  30 ,  31 . The narrowing portion is thus formed in a manner narrowing in a stepped manner in this exemplary embodiment. It has a face  29   a  extending transversely to the longitudinal axis of the shaft element  20 , and a face  29   b  extending parallel to the inner side  74  of the housing part  70 , said faces immediately adjoining one another. For the sake of clarity, the reference signs are only indicated in  FIG. 3 . The face  29   b  extending parallel to the inner side  74  also extends substantially parallel to the longitudinal axis A of the shaft element  20 . The faces, or contact faces  29   a,    29   b  are arranged substantially orthogonally to one another, such that the shaft element  20  forms a perpendicular ledge. It is conceivable to provide the transition between the contact faces  29   a,    29   b  with a small rounding. It is not necessary for the shaft element  20  to bear on the housing part  70  in the region of the transition between the contact faces  29   a,    29   b.  As can be seen in  FIG. 3 , the housing part  70  also has a rounded edge in this region, this being advantageous for injection-molding reasons. However, it is also conceivable to provide diagonal faces, several steps or a combination of diagonal faces and stepped portions, in order to achieve radial and axial mounting of the shaft element  20 . 
         [0040]    The second shaft end  22  in turn is formed such that it is not in contact with the housing part  70 . As can be seen in  FIG. 3 , an air gap arises between the second shaft end  22  and the housing part  70 , in order to avoid friction between the second shaft end and the housing part  70 . Also provided at the second shaft end  22  is a recess  33  for receiving a magnet element  51 . The recess  33  is configured in a multistep manner, representing a negative of the shape of the magnet element  51 . The magnet element  51  and the recess  33  are configured such that the magnet element  51  terminates flush with the end face of the shaft element  20 . 
         [0041]    Advantageously, the shaft element  20  is produced with a precise fit in the region of the bearing portions  24 ,  29 . This relates to the tolerance with regard to the position relative to the longitudinal axis A of the shaft element. In particular, it is advantageous to produce the horizontal contact face  29   a  with a precise fit, or with a low tolerance, with regard to the spacing from the end face of the second shaft end  22 . Furthermore, the precision fit also relates to the radial dimensions of the contact faces  29   b  and  26  of the first and second bearing portions  24 ,  29 , in order to achieve fixed mounting with simultaneously low friction. The friction can also be reduced for example by means of lubricant, a suitable material or material pair of the housing part  70  and shaft element  20 . However, a high precision fit furthermore has the advantage that the region of the second shaft end is able to be sealed off without additional sealants. 
         [0042]    As clearly illustrated in  FIG. 2 , the housing part  70  is configured to receive the shaft element  20  and the sensor element  5 . The housing part  70  is able to be divided into two portions  80 ,  90 , wherein the first portion is configured to receive the shaft element  20  and the second portion  90  is substantially configured to receive the sensor element  5 . There is no passage between the two portions  80 ,  90 , and so it is impossible for moisture to penetrate from the first portion into the second portion  80 ,  90  of the housing part  70 . On the contrary: a wall  85  separates the cavity which is intended to receive the shaft element  20  from the second portion  90  of the housing part  70 . 
         [0043]    The first portion  80  of the housing part  70  has a cylindrical basic shape (see  FIG. 4 ). The outer face of the first portion extends substantially in a planar manner, wherein a plurality of triangular ribs  81  are arranged on the outer lateral surface. These ribs  81  serve to anchor the housing part  70  within the housing  7 , as can be seen in  FIG. 1 . Furthermore, the first portion has a recess or a cavity in which the shaft element  20  is received. The shaping of the cavity is configured in order to allow mounting of the shaft element  20 , as described above. 
         [0044]    The second portion  90  of the housing part  70  is formed in a substantially platelike manner and arranged on the end side of the first portion, or on the wall  85 , which is located opposite the opening. As can be seen in  FIGS. 2 and 3 , the top side  91  of the second portion is configured in a substantially planar manner. By contrast, the underside  92  has a profiled structure in order to receive the sensor element  5 . Reference is made to  FIG. 4  in this regard. It can be seen therein that the underside  92  has an edging  93  which forms a recess into which the sensor element  5  is able to be inserted. Furthermore, a plurality of riblike and pinlike protrusions  94 ,  95  are provided, such that conductor tracks  59  of the sensor element  5  are able to be positioned exactly and are held in the intended position. The underside  92  of the second portion  90  is open toward the outside, such that the sensor element  5  is able to be inserted easily into the recess. The housing part  70  is overmolded together with the sensor element and the shaft element  20 . A cover for the sensor element  5  is not necessary. 
         [0045]    The housing  7  of the sensor device  1  has a plurality of fastening members  99 , of which only one is indicated by way of example in  FIG. 1 , via which the housing  7  is able to be fastened to a motor vehicle by means of screws or the like. Furthermore, the housing  7  has a sleeve  73 , configured in an oval manner, which serves to receive a plug connection. In the sleeve  73 , it is possible for example to accommodate a plug for a circuit board, which is connected to the conductor tracks  59  of the sensor element  5 . This sleeve  73  is adjoined by a portion  98  enclosing the housing part  70 . This portion  98  encloses the housing part  70  virtually completely apart from a region which is comprised by the collar  46 . In particular, the first portion  80  of the housing part  70  is also enclosed by the housing  7 , in particular overmolded therewith. In this way, the wall of the first portion  80  of the housing part  70  is pressed against the bearing portions  24 ,  29  of the shaft element  20 . This ensures that the second bearing portion  24  bears directly on the inner side  74  of the housing part  70 . 
         [0046]      FIGS. 5 and 6  illustrate a second exemplary embodiment which differs substantially by way of a different design of the inner side  74  of the housing part  70 . Therefore, the abovementioned reference signs are used in the following text as long as the elements are identical elements. 
         [0047]    According to the second exemplary embodiment, the housing part  170  has, on the inner side  74  of the recess, a plurality of contact faces  175 ,  176  which are formed in a segmented manner and which interact with the first and second bearing portions  24 ,  29  of the shaft element  20 . In the region of the bearing portions  24 ,  29 , the inner face  74  is subdivided into a plurality of contact face segments  175 ,  176  by means of grooves  177 ,  178 . The grooves  177 ,  178  extend substantially parallel to the longitudinal axis A of the shaft element, or in a vertical direction. In the region of the first bearing portion  24 , a plurality of contact faces  175 , configured in a rectangular manner, are thereby produced in a manner extending around the circumferential face, said contact faces  175  being interrupted by means of the grooves  177 . In the region of the second bearing portion  29 , the grooves extend in a manner corresponding to the shape of the blind hole, or in a stepped manner, such that the contact faces  176  are separated from one another here, too. The depth of the grooves  177 ,  178  can vary depending on the application. They serve as a lubricant reservoir. Furthermore, these grooves can also be used in order to receive dirt particles or the like. As a whole, less friction arises in this way upon rotation of the shaft element  20  within the housing part  70 . 
         [0048]    The claims associated with the application do not represent any renunciation of the achievement of further protection. 
         [0049]    If it is found in the course of the procedure that a feature or a group of features is not absolutely necessary, the applicant&#39;s aim is now already to draft at least one independent claim which no longer has the feature or group of features. This may involve, for example, a subcombination of a claim present on the filing date or a subcombination, limited by further features, of a claim present on the filing date. Such claims or combinations of features which are to be newly drafted should be understood as also being covered by the disclosure of this application. 
         [0050]    It should furthermore be noted that configurations, features and variants of the invention which are described in the various embodiments or exemplary embodiments and/or shown in the figures are combinable with one another as desired. Individual features or several features can be exchanged with one another as desired. Combinations of features which result therefrom should be understood as also being covered by the disclosure of this application. 
         [0051]    Back-references in dependent claims should not be understood as being any renunciation of the achievement of independent, objective protection for the features of the dependent claims with back-references. These features can also be combined with other features as desired. 
         [0052]    Features which are disclosed only in the description or features which are disclosed in the description or in a claim only in conjunction with other features can in principle be of independent significance which is essential to the invention. Therefore, they can also be adopted individually into claims for delimitation from the prior art.