Abstract:
A component for a sensor having a sensor element and having an output interface for the outputting of an electrical signal, which is dependent on a physical variable, from the sensor element to the output interface, including—a circuit with at least one first signal path for receiving the electrical signal from the sensor element and for conducting the electrical signal to the output interface, and a second signal path, which differs from the first signal path, for conducting the electrical signal to the output interface,—wherein an activity of the first signal path or of the second signal path is dependent on a position of the component in the sensor.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is the U.S. National Phase Application of PCT International Application No. PCT/EP2016/051571, filed Jan. 26, 2016, which claims priority to German Patent Application No. 10 2015 201 480.0, filed Jan. 28, 2015, the contents of such applications being incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a sensor for measuring a physical variable and a control device for a vehicle having the sensor. 
       BACKGROUND OF THE INVENTION 
       [0003]    WO 2010/037810 A1, which is incorporated by reference discloses a sensor for measuring a physical signal. The sensor has a leadframe which, as a circuit carrier, carries the sensor component parts of the sensor and at the same time connects the same together. 
       SUMMARY OF THE INVENTION 
       [0004]    An aspect of the invention aims to improve the known sensor. 
         [0005]    According to one aspect of the invention, a module for a sensor having a sensor element and an output interface for outputting an electrical signal which is dependent on a physical variable from the sensor element at the output interface comprises a circuit having at least one first signal path for receiving the electrical signal from the sensor element and for conducting the electrical signal to the output interface, and a second signal path, which differs from the first signal path, for conducting the electrical signal to the output interface, wherein an activity of the first signal path or of the second signal path depends on a position of the module in the sensor. 
         [0006]    The module specified is based on the thought that a sensor is generally used in an application-dependent application environment. Thus, it is possible that different control devices in a vehicle, in which the sensor can in principle be used, tap off the signal at different pins of the sensor. Although in this way the sensor element itself can be fabricated in a standardized manner and economically, the sensor itself once more has to be produced in an application-specific and therefore customer-specific manner, which drives up the production costs. 
         [0007]    Here, the specified module intervenes with the proposal to route the signals output from the sensor element. For this purpose, the specified module has the different signal paths. Depending on which signal path is active, a corresponding pin on an application arranged above the sensor can be supplied with the electrical signal from the sensor component. By means of simply offsetting the specified module in the sensor, it is thus possible to set the different application-dependent configurations, wherein both the sensor element and the module itself can be fabricated economically in a standardized form. 
         [0008]    In a preferred configuration, the output interface of the specified module therefore comprises various output pins, the two signal paths being configured to conduct the electrical signal to different output pins. 
         [0009]    In an alternative or additional configuration of the idea previously explained, the different signal paths can also be used to implement different application-dependent functions before the electrical signal is output to the output interface. For this purpose, there is at least one electric component in the module, via which the first and/or the second signal path is led. 
         [0010]    The electric component can, for example, be configured to filter interference out of the electrical signal. In this way, the electromagnetic compatibility of a sensor having the specified module can be raised. 
         [0011]    In an additional development of the module, the circuit can be encapsulated in an embedding compound. As a result of encapsulating the module, the signal paths and, if appropriate, the electric components, are protected. The module can then be touched without difficulty for the purpose of positioning in the sensor. In addition, mechanical stress on the modules can be reduced, since the modules can be positioned in the embedding compound at points of symmetry which represent so-called neutral fibers, at which the mechanical stress input is low. 
         [0012]    In order to achieve the highest possible protection of the electric component parts of the specified module, the specified module should comprise pin areas via which the signal paths are exposed to the outside from the embedding compound in order to make contact with the sensor element and the output interface. All other electric component parts of the specified module can thus be protected from the embedding compound. 
         [0013]    In another development of the specified module, the embedding compound can be a resin. 
         [0014]    According to a further aspect of the invention, a sensor for measuring a physical variable comprises a sensor element for measuring and outputting an electrical signal which is dependent on the physical variable, a substrate carrying the sensor element and having a conductor track, an output interface for outputting the electrical signal to a higher-order device, and one of the specified modules for conducting the electrical signal from the conductor track of the substrate to the output interface. 
         [0015]    According to a further aspect of the invention, a control device for a vehicle for controlling a behavior of the vehicle on the basis of a measured physical variable comprises a specified sensor for measuring the physical variable. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The above-described properties, features and advantages of this invention and the manner in which these are achieved become clearer and considerably more understandable in conjunction with the following description of the exemplary embodiments, which will be explained in more detail in conjunction with the drawings, in which: 
           [0017]      FIG. 1  shows a schematic view of a vehicle having a vehicle dynamic control system, 
           [0018]      FIG. 2  shows a basic illustration of a rotational speed sensor in the vehicle from  FIG. 1 , 
           [0019]      FIG. 3  shows a schematic illustration of a reading head of the rotational speed sensor from  FIG. 2  in an intermediate production state, 
           [0020]      FIG. 4  shows a schematic sectional view of an alternative reading head, 
           [0021]      FIG. 5  shows a schematic plan view of the alternative reading head from  FIG. 4 , 
           [0022]      FIG. 6  shows a schematic sectional view of a module from the alternative reading head, and 
           [0023]      FIG. 7  shows a schematic view of an ideal, theoretical arrangement of various components for the module from  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    In the figures, the same technical elements are provided with the same designations and are described only once. 
         [0025]    Reference is made to  FIG. 1 , which, in schematic form, shows a vehicle  2  having a chassis  6  carried on wheels  4 . Two of the wheels  4  are driven via an axle  8  by an internal combustion engine  10 . The basic mode of action of an internal combustion engine is known per se and is therefore not to be discussed further below. 
         [0026]    In a manner known per se, see for example DE 10 2012 206 552 A1, which is incorporated by reference, the valve control times of the internal combustion engine  10  can be set by a camshaft adjuster  12 , in order to influence the load point of the internal combustion engine  10  for better fuel utilization in various rotational speed ranges. For this purpose, a camshaft drive device  14  measures the rotational speed  20  of the internal combustion engine  10  via a rotational speed sensor  18  and, by using a control signal  22 , drives the camshaft adjuster  12  on the basis of the measured rotational speed  20 . The generation of the control signal  18  on the basis of the rotational speed  20  is known per se and is not to be explained further below. Details relating thereto will be found in the relevant specialist literature. 
         [0027]    The rotational speed sensor  18  is formed in a particular way within the context of the present explanation. Before this is discussed in more detail, the basic structure of the rotational speed sensor  18  itself should be explained in more detail. To this end, reference is made to  FIG. 2 , which shows a schematic view of a possible embodiment of the rotational speed sensor  18  in the motor vehicle  2  from  FIG. 1 . 
         [0028]    The rotational speed sensor  18  in the present embodiment is implemented as an active rotational speed sensor which comprises an encoder disk  26  rotationally firmly fixed to the rotor of the internal combustion engine  10  (not shown), and a reading head  28  fixed to the chassis  6  in a fixed location. 
         [0029]    The encoder disk  26  in the present embodiment consists of magnetic north poles  30  and magnetic south poles  32  lined up in a row, which jointly excite a magnetic encoder field  33  indicated by an exemplary arrow. If the encoder disk  26  fixed to the rotor of the internal combustion engine  10  rotates with the latter in the direction of rotation  34 , then the magnetic encoder field  33  rotates therewith. 
         [0030]    The reading head  28  in the present embodiment comprises a measuring sensor  35  which, depending on the movement of the magnetic encoder field  33 , generates an electrical transmitter signal  39 . For this purpose, it is possible to use any desired measuring principle, such as for example a measuring principle based on the magnetoresistive effect. The electrical transmitter signal  39  therefore depends on the rotational speed  20  that is to be measured. 
         [0031]    The transmitter signal  39  can then be conditioned in a signal processing circuit  40  arranged in the reading head  28 . As a rule, here a pulse signal  42  is generated from the transmitter signal  39 , wherein the pulse signal  42  comprises a number of pulses, which depends on the rotational speed to be measured, over a predetermined time interval. This pulse signal  42  is then output to the camshaft control device  14 , which is then able to derive the rotational speed  20  by counting the pulses in the pulse signal  42 . 
         [0032]    Since, because of the internal combustion engine  10 , not inconsiderable interference fields occur in a manner known per se, a supporting magnet  43  is arranged in the reading head  28 , counteracting these interference fields and thus permitting a measurement of the rotational speed  20  with low tolerances. The supporting magnet  43  should therefore be chosen to be correspondingly powerful in order to be able to counteract the interference fields adequately. 
         [0033]    Conventionally, the reading head  28  is implemented on a leadframe, such as is known, for example, from the prior art WO 2010/037810 A1, which is incorporated by reference, mentioned at the beginning. Such a leadframe is shown by way of example in  FIG. 3  and referenced by the designation  44 . The leadframe  44  comprises a holding frame  46 , a fitting island  48 , on which the reading head  28  is held and wired, two dam bars  50  and two contact terminals  52 . Here, the dam bars  50  hold the contact terminals  52  directly and the fitting island  48  via an auxiliary frame  53  on the holding frame  46 . In the leadframe  44 , the holding frame  46 , the fitting island  48 , the dam bars  50 , the contact terminals  52  and the auxiliary frame  53  are formed as one-piece punched parts or punched frames, in which the aforementioned elements are shaped by punching out of an electrically conductive metal sheet. 
         [0034]    On the fitting island  48 , within the context of the present embodiment, the measuring sensor  35 , for example in the form of a magnetoresistive element, and the signal evaluation circuit  40  are applied and electrical contact is made therewith, for example by soldering or adhesive bonding. The measuring sensor  35  and the signal evaluation circuit  40  are also connected to each other via a bonding wire  54 , so that the sample signal  39  can be transmitted between measuring sensor  35  and the signal evaluation circuit  40  via the fitting island  48  and the bonding wire  54 . 
         [0035]    In the present embodiment, the fitting island  48  is connected directly to one of the two contact terminals  52 , while the other of the two contact terminals  52  is isolated electrically from the fitting island  48  and is connected to the signal evaluation circuit  40  via a further bonding wire  54 . In this way, the data signal  42  can be output from the signal evaluation circuit  40  via the two contact terminals  56 . 
         [0036]    In the context of the present embodiment, the holding frame  46  has two transport strips  58 , which run in parallel with respect to each other and are connected to each other via connecting webs  60 . Formed on the transport strips  58  are transport holes  62 , in which a transport tool, not specifically illustrated, can engage and move the leadframe  44 . Also formed on the transport strips  58  is an index hole  64 , by means of which the position of the leadframe  44  can be determined and therefore controlled during transport. 
         [0037]    To protect the reading head  28 , a housing can be formed around the fitting island  48  carrying the reading head  28  and a part of the contact terminals  52 . The housing can, for example, be formed as a protective compound around the reading head  28 , for which purpose, for brevity, reference is made to the relevant prior art such as, for example, DE 10 2008 064 047 A1, which is incorporated by reference. 
         [0038]    As a rule, however, said reading head  28  not only transmits the pulse signal  42  to the camshaft drive device  14  but also other signals which, for example, can be used for fault detection. In addition, in sensors such as the rotational speed sensor  18  described, measures which increase the electromagnetic compatibility, called EMC, are also necessary. 
         [0039]    Depending on the type of the control device receiving the pulse signal  42 , such as the camshaft drive device  14 , or else also depending on the manufacturer of the latter, the pulse signal  42  must be output on another contact terminal  52 . 
         [0040]    Here, the exemplary embodiment intervenes with the proposal to use a module  65  illustrated in  FIGS. 4 and 5  as an adapter and to rewire the individual signals from the reading head  28  into the contact terminals  52  in a corresponding manner. For this purpose, the module  65  has multiple pin areas  66 . Each pin area  66  can both receive a signal from the measuring sensor  35  or the signal processing circuit  40  and also output a signal to an output interface  67 . The individual pin areas  66  can be wired to one another by signal paths, not specifically illustrated. 
         [0041]    The module  65  can have more pin areas  66  than is completely necessary for routing the signals such as the pulse signal  42 . In this way, by means of a simple positional change of the module  65  (for example by rotation in  FIG. 4 ), another wiring response of the signals in the reading head  28  can be brought about. 
         [0042]    Furthermore, additional components  68 , such as filter components, can be wired in the module  65  in order to filter out the aforementioned interference from the signals, such as the pulse signal  42 , and thus to increase the EMC. These components  68  can be embedded in the module  65  in the manner below, which is to be explained in more detail by using  FIGS. 6 and 7 . 
         [0043]    The module  65  can be implemented as a printed circuit board module and comprise multiple insulating layers  69  stacked one above another, to which conductor tracks  70  are applied. The aforementioned components  68  of the module  65 , which are intended to increase the electromagnetic compatibility of the reading head  28  and therefore of the rotational speed sensor  18 , are carried on the conductor tracks  70  or on the insulating layers  69 . The conductor tracks  70  themselves can be part of the aforementioned signal path or implement the latter completely. 
         [0044]    Some of the modules  68  in the present embodiment are embedded in an embedding compound  71  between two insulating layers  69  of the module  65  implemented as a printed circuit board module. In this way, these modules  68  are protected against external influences. The individual layers can be connected electrically to one another via contact-making holes  72 . Furthermore, soldering points, which implement the aforementioned pin areas  66 , can be present on the module  65 . 
         [0045]    The embedding according to  FIG. 6  should be carried out in a special way. Individual mechanical stress  73  which is brought about by the individual mechanical components  68 , for example as a result of temperature movements, and can add up to a total mechanical stress  74 , can deform the module  65 . As a result of this deformation, amongst other things the soldering points  72  can be detached from the higher-order circuit, and can lead to failure of the reading head  28  and therefore the rotational speed sensor  18 . 
         [0046]    Therefore, the module  65  should be implemented as symmetrically as possible, in order that the individual mechanical stress  73  brought about by the individual components  68  can be mutually canceled and thus a total mechanical stress  74  can be minimized. For this purpose, there are various compensating components in the module  65 , which are able to counteract an individual mechanical stress  73 . It is not absolutely necessary to implement all the compensating components shown actually in the module  65  in order to implement the idea behind the embodiment. The individual compensating components shown are intended to illustrate by way of example how the components  68  in the module  65  can be arranged symmetrically in order to keep the total mechanical stress  74  below a specific, tolerable limit. 
         [0047]    Firstly, it is possible to introduce, as a compensating component, a redundant conductor track  70 ′ and a redundant insulating layer  69 ′, in order to form the conductor track arrangement symmetrically in the printed circuit board module  66 . Consequently, a redundant embedding compound  71 ′ is also introduced here, which can be different from the embedding compound  71  or else chosen to be the same as the latter. 
         [0048]    As a further possibility, individual ones of the components  68  can be arranged symmetrically in relation to one another. The advantage here is that no redundant elements have to be introduced into the module  65  as compensating components. In order to compensate differences in the geometric, material or other condition between the two embedded components  68 , it is also possible to dimension the contact-making means  75  of the conductor tracks  70  to the individual embedded components  68  geometrically differently, which is indicated in  FIG. 6  by contact-making means  75  of different widths on the two embedded components  68 . 
         [0049]    In addition, redundant recesses  76  can be introduced into the printed circuit board module  66  as compensating components. 
         [0050]    The ideal case of the module  65  is illustrated in  FIG. 7 . Here, all the distances  77  between the individual components  68  are implemented symmetrically in relation to one another in relation to an axis of symmetry  78 . However, in practical terms this ideal concept cannot be implemented on its own, since the components  68  could then no longer make contact with the conductor tracks  70 . However, during the design of the module  65 , it should be attempted to reach the ideal case as far as possible. 
         [0051]    As a result of embedding the components  68  in the module  65 , it is possible to achieve considerable miniaturization. Furthermore, it is not necessary to encase the individual components  68  once more in an extra encapsulation step, for example by pressure injection molding, with the protective compound mentioned above in the context of  FIG. 3 . As a result of enclosing the entire area of the components with the embedding compound  71 , for example in the form of a resin, such a protective compound is obsolete. At the same time, a resin offers better thermal properties for dissipating heat generated by power loss of the component parts as, for example, air convection.