Abstract:
A modular sensor assembly for performing measurement or calibration is disclosed, comprising a sensing module comprising a threaded spigot, a first slip ring conductive track, and a second slip ring conductive track; a base module comprising a threaded receptacle, a first conductor, and a second conductor; wherein the sensing module is detachably mounted to the base module by rotating the threaded spigot into the threaded receptacle thereby forming a first electrical connection between the first slip ring conductive track and the first conductor, and a second electrical connection between the second slip ring conductive track and the second conductor.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates generally to modular sensor assemblies, and more particularly to mechanical and electrical connection of a detachable sensing module to a base module. 
         [0002]    Sensors of pressure, temperature, current, etc. are used in a wide range of industrial and consumer applications, including measurement and calibration of components and instruments. Flexibility to use one measurement or calibration system for various measurement or calibration tasks can be achieved by providing detachable sensing modules which can be used with the same base module. Depending upon a particular application, the measurement or calibration system should be able to operate under harsh environmental, vibration, impact, and other operating conditions. The connection between the sensing module and the base module should be able to withstand high pressure for applications involving pressure measurement or calibration. 
         [0003]    Known solutions, e.g., Heise PTE-1 Handheld Pressure calibrator available from Dresser Inc. of Newtown, Conn., BETAGAUGE II Pressure Documenting Calibrator available from Hotek Technologies of Tacoma, Wash., MFT 4000 Multifunctional Modular Calibrator available from Meriam Process Technologies of Clevelend, Ohio, and Quickcal 190 Automated Pressure Calibrator available from Transmation Inc. of Everett, Wash., mostly employ sensing modules mountable inside a base module. Mounting a sensing module inside the base module can be undesirable, e.g., in hand held applications where the size of the base unit is of a paramount importance. Conversely, mounting a sensing module outside of the base module poses numerous challenges related to providing reliable mechanical and electrical connection. 
         [0004]    Thus, a need exists to provide means and methods of reliable mechanical (including pressure-resistant) and electrical connection of detachable sensing modules to a base module. A further need exists to ensure that the ability of each of the modules (i.e., sending modules and base module) to withstand environmental, handling, storage, and other operational conditions is not dependent upon the modules being mated together. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0005]    A modular sensor assembly for performing measurement or calibration is disclosed, comprising a sensing module comprising a threaded spigot, a first slip ring conductive track, and a second slip ring conductive track; a base module comprising a threaded receptacle, a first conductor, and a second conductor; wherein the sensing module is detachably mounted to the base module by rotating the threaded spigot into the threaded receptacle thereby forming a first electrical connection between the first slip ring conductive track and the first conductor, and a second electrical connection between the second slip ring conductive track and the second conductor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  illustrates an exploded view of one embodiment of an interface between a sensing module and a base module of a measurement or calibration device. 
           [0007]      FIG. 2  illustrates a cross-section view of one embodiment of an interface between a sensing module and a base module of a measurement or calibration device. 
           [0008]      FIG. 3  illustrates one embodiment of a base module of a measurement or calibration device adapted to receive two sensing modules. 
           [0009]      FIG. 4  illustrates a cross section view of one embodiment of an interface between a sensing module and a base module of a measurement or calibration device. 
           [0010]      FIG. 5  illustrates an electrical diagram of one embodiment of a sample implementation of the physical layer of a data interface between a sensing module and a base module of a measurement or calibration device. 
       
    
    
       [0011]    The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the present invention. In the drawings, like numerals are used to indicate like parts throughout the various views. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0012]    There is provided a modular sensor assembly including a base module of a measurement or calibration device, and one or more interchangeable sensing modules externally mountable to the base module.  FIG. 1  shows an exploded view, and  FIG. 2  shows a cross-section of one embodiment of the interface of a sensing module and a base module. In one aspect, the sensing module  100  can be provided, depending upon the application requirements, e.g., by a pressure sensor, a voltage sensor, a temperature sensor, a humidity sensor, a flow sensor, a pressure calibrating module, a voltage calibrating module, a current calibrating module, etc. A skilled artisan would appreciate the fact that the present invention can be practiced with alternative types and configurations of sensing modules, and hence the description set forth herein is not intended to restrict or limit the practice of the present invention to any particular type of a sensing module. 
         [0013]    The sensing module  100  can be externally mountable to a base module  202 , as best viewed in  FIG. 3 .  FIG. 3  illustrates a base module  202  which is adapted to receive two sensing modules  100  and  101 . In alternative embodiments, the base module  202  can be adapted to receive one or more sensing modules  100 . 
         [0014]    Referring again to  FIGS. 1 and 2 , components of the sensing module  100  can, in one aspect, be incorporated in a housing  102 . In one aspect, the sensing module  100  can have substantially cylindrical form factor. In another aspect, the sensing module  100  can include a threaded spigot  104 . The threaded spigot  104  can provide a mechanical attachment of the sensing module  100  to the interface part  120  of the base module  202 . The threaded spigot  104  can be threadably attached to the base module receptacle  122  having an internal threaded part. The sensing module  100  can be driven into engagement with the base module  202  by an operator placing the spigot  104  into the base module receptacle  122  and rotating the sensing module  100  relative to the base module  202 . Thus, the threaded interface can provide for establishing reliable mechanical connection of the sensing module  100  to the base module  202  using only hand movement force of the operator. 
         [0015]    In another aspect, the diameter  106  of the spigot  104  can be the only controlled dimension of the interface between the sensing module  100  and the base module  202 , thus allowing the sensing module  100  to be shaped in numerous form factors and in continuum of dimensions to satisfy alternative application needs, as well as be adapted to facilitate a secure grip of the sensing module  100  by the operator&#39;s hand. 
         [0016]    In another aspect, the spigot  104  can be hollow, i.e., can have an opening  132  which, together with the opening  134  in the base module receptacle  122 , can allow gas or liquid to move freely between the inside volumes of the sensing module  100  and the base module  202 , which can be necessary for certain applications, e.g., pneumatic or hydraulic pressure measurement or calibration. 
         [0017]    In one embodiment, the mechanical connection between the sensing module  100  and the base module  202  can be sealed to withstand high pressure values, which can be necessary, e.g., for applications involving pneumatic or hydraulic pressure measurement or calibration. For example, in one embodiment the mechanical connection between the sensing module  100  and the base module  202  can withstand pressure values up to 1000 bar. In one embodiment, the environmental sealing of the connection can be provided by one or more O-rings  302 ,  303 , as best viewed in  FIG. 4 . 
         [0018]    In another aspect, both the sensing module  100  and the base module  202  can remain sealed when disconnected from each other.  FIG. 4  illustrates the base module interface part  120  being equipped with the isolation valve  304  which is in a normally closed state supported by a loaded spring  306  when no sensing module  100  is connected to the base module  202 , thus shuttering the opening to the base module  202 . The isolation valve  304  can be pushed to an open state by the spigot  104  when the sensing module  100  is rotatably tightened and connected to the base module  202 . Conversely, when the sensing module  100  is being rotatably loosened and disconnected from the base module  202 , the isolation valve  304  returns to its normally closed state, preventing the ejection of gas or liquid from the base module  202 . A skilled artisan would appreciate the fact that other designs of the isolation valve  304  are within the spirit and the scope of the present invention. 
         [0019]    In another aspect, the sensing module  100  can comprise one or more slip ring conductive tracks  110 ,  111  providing electrical coupling between the components of the sensing module  100  and the base module  202 . In one embodiment, best viewed in  FIG. 2 , the slip ring conductive track  110  provides power transmission between the base module  202  and the sensing module  100 . The slip ring conductive track  111  provides data transmission between the base module  202  and the sensing module  100 . A skilled artisan would appreciate the fact that one or more conductive tracks providing power transmission, data transmission, and other functions are within the scope and spirit of the present invention. 
         [0020]    In one embodiment, the slip ring conductive tracks  110 ,  111  can be provided by precious metal plating embedded into a non-conductive material (e.g., plastic). 
         [0021]    In one embodiment, best viewed in  FIG. 4 , a pair of conductors in the form of spring loaded pins  310 ,  311  can be mounted on the interface part  120  of the base module  202  and can be adapted to make electrical contact with the respective slip ring conductive tracks  110 ,  111  when the sensing module  100  and the base module  202  are connected together. The pins  310 ,  311  can be made of a conductive material and be electrically coupled to the data transmission and power transmission circuitries of the base module  202 . 
         [0022]    In a further aspect, the spigot  104  and base module receptacle  122  can be made of a conductive material, and adapted to carry electrical ground connection between the sensing module  100  and the base module  202 . 
         [0023]    In one embodiment, bi-directional data transmission between the sensing module  100  and the base module  102  can be performed via a single data wire including a slip ring conductive track  111  in contact with a spring loaded pin  311  as described herein. The single-wire interface can provide half-duplex serial data transmission and operate according to the following sample specifications: 1 start bit, 8 data bits, 1 stop bit, odd parity, 115 Kbaud. The electrical diagram of a sample implementation of the physical layer of the data interface is shown in  FIG. 5 . A universal asynchronous receiver/transmitter (UART)  402  on the sensing module  100  side can communicate with a UART  403  on the base module  202  side over a single data line  404  via two non-inverting open collector drivers  406  and  407  buffering the output of the respective transmission ports  408 ,  409  of the two UARTs. The data line  404  can be pulled high by a pull-up resistor  410  when a transmission port is driven high. The respective receiving ports  412 ,  413  of the two UARTs can be coupled to the data line  404 , thus providing half-duplex serial data communication via a single data line  404 . 
         [0024]    The power line  420  can be provided by a second conductive slip ring track  110  in contact with a spring loaded pin  310  as described herein, and the ground line  430  can be provided by the conductive spigot  104  in contact with the base module receptacle  122 , as described herein. 
         [0025]    In a further aspect, a specific hardware and software protocols can be employed to facilitate the data exchange over the data transmission line provided by the slip ring conductive track  111  and one or more brushes or pins. 
         [0026]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.