Patent Publication Number: US-2023164941-A1

Title: Process for reversibly connecting a sensor to an inlet

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is related to and claims the priority benefit of German Patent Application No. 10 2018 127 014.3, filed on Oct. 30, 2018, and U.S. patent application Ser. No. 16/668,936, filed Oct. 30, 2019, the entire contents of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a process connection for a sensor and to a manufacturing method for such a process connection. 
     BACKGROUND 
     Process connections for sensors are used in a wide variety of industrial processes. Process connections serve to bring various kinds of sensors, for example a conductivity sensor, into contact with the process medium of the process. The device carrying the process, for example a pipe or other container, has a process inlet for this purpose. The process inlet and the process connection must be connected to each other in a leakproof and disconnectable manner. In order to achieve a leakproof closure of the process inlet, a process seal is installed between the process connection and the process inlet. In addition, a fixing element is used, for example a clamp, a screw or a union nut, in order to connect the process connection to the process inlet in a disconnectable manner. The fixing element presses the process connection onto the process seal in order to prevent the process medium from escaping. The disconnectable connection of process inlet and process connection makes maintenance of the process connection or of the sensor possible. 
     Certain properties of the process connection and of the process inlet are subject to various requirements, depending on the field of application, which are defined by national and international standards (such as, for example, DIN 11851, DIN 11864-1, ISO 2852, etc.) or industry quasi-standards of the application sectors (for example, “Varivent,” “Biocontrol,” etc.). Particularly in processes of the food and beverage industry, there are strict regulations regarding the hygiene of process connections. 
     The hygienic properties of process connections are mainly affected by any gaps, edges or seals present, since deposits can easily form there. There are hygienic process connections which have, for example, few seals, but which in turn only fit precisely one process inlet having a particular diameter. However, since there is a multiplicity of process inlets each having different inlet diameters, the cost of realizing a variety of process connections for a sensor family is very high. 
     SUMMARY 
     An object of the present disclosure is to provide a process connection for a sensor which can deliver excellent hygienic properties and be usable for a plurality of process inlets in an economical manner. 
     This object is achieved by claim  1 . 
     The present disclosure relates to a process connection for a sensor. The process connection is suitable for being connected to a process inlet via a process seal and a fixing element. The process connection includes a sensor housing and a clamping element. The sensor housing has a housing body and a housing collar. The housing body is designed to receive the sensor. The housing collar extends around the housing body and has a first sealing section encircling the housing body and also has a contact area. The housing collar is formed integrally with the housing body. The first sealing section is suitable for receiving the process seal in order to connect the process inlet to the housing collar in a fluid-tight manner. The clamping element has a contact area which is suitable for coming into contact with the contact area of the housing collar in order to press the housing collar onto the process seal. 
     The process connection according to the present disclosure offers many advantages, wherein only a few advantages are to be mentioned below as examples. One advantage which arises from the single-piece design of the sensor housing, especially, of the housing body and of the housing collar, is that additional sealing points are avoided. On the one hand, there are thus fewer gaps in which deposits could form, which has an advantageous effect on the hygienic properties of the sensor housing, and on the other hand, there are fewer elements to be maintained in the process connection. The advantage of a separate clamping element is that the clamping element can be used to receive the contact forces of the fixing element and transfer them to the sensor housing. The housing collar can thus be optimized for the particular manufacturing method and adapted to the respective diameters of the process inlets. Thanks to the process connection according to the present disclosure, it is thus possible to achieve flexible production and at the same time a reliable sealing effect. 
     According to one embodiment, the clamping element is annular and has an axially circumferential first sealing section which is suitable for contacting the process seal in order to connect the process inlet to the clamping element in a fluid-tight manner. 
     According to one embodiment, the process connection comprises an annular sealing element which is arranged between the sensor housing and the clamping element. 
     According to one embodiment, the annular sealing element is arranged between the housing body of the sensor housing and the clamping element. 
     According to one embodiment, the first sealing section of the housing collar is arranged on one end face at a radially outer end of the annular housing collar. 
     According to one embodiment, the first sealing section has one of the following cross-sectional shapes: flat, conical or groove-shaped, especially, semicircular or rectangular. 
     According to one embodiment, the sensor housing has a transition region which is arranged between the housing collar and the housing body and has a radius between 3.2 mm and 6 mm or greater than 6 mm. 
     The present disclosure also relates to a manufacturing method for the process connection according to the present disclosure as claimed in claim  8 . 
     For a prespecified process inlet and for a prespecified process seal, the manufacturing method according to the present disclosure for the process connection according to the present disclosure comprises the following steps: fabricating the sensor housing so that the housing body and the housing collar are integrally formed; adapting the housing collar so that the housing collar has an outer diameter as well as a first sealing section which are suitable for the prespecified process inlet and process seal; and fabricating the clamping element. 
     The manufacturing method according to the present disclosure has the advantage that the sensor housing can be manufactured in a material-saving manner. A high-quality material can thus be used for the sensor housing without the production costs thereof being excessively burdened. By adapting the housing collar to the outer diameter of the process inlet, it is possible to adapt the sensor housing to any outer diameter of a process inlet. 
     According to one embodiment, the sensor housing is manufactured by injection molding. 
     According to one embodiment, the adaptation step of the housing collar is carried out by a separating method, for example a machining method. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure is explained in more detail on the basis of the following description of the figures in which: 
         FIG.  1    shows a cross-sectional view of a process connection according to the present disclosure connected via a sealing ring to a process connection; 
         FIG.  2    shows a cross-sectional view of an embodiment of the process connection shown in  FIG.  1   ; 
         FIG.  3    shows a detail view of  FIG.  2   ; 
         FIG.  4    shows a cross-sectional view of an alternative embodiment of a process connection; 
         FIG.  5    shows a cross-sectional view of an alternative embodiment of the process connection shown in  FIG.  2   ; 
         FIG.  6    shows a cross-sectional view of an alternative embodiment of the process connection shown in  FIG.  2   ; and 
         FIG.  7    shows a cross-sectional view of an alternative embodiment of the process connection shown in  FIG.  2   . 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    shows a process connection  1  for a sensor. The process connection  1  includes a sensor housing  10  and a clamping element  20 . The process connection  1  is configured for being connected to a process inlet  2  via a process seal  3  and a fixing element  4  (shown in  FIGS.  2  and  3   ). 
     The sensor housing  10  has a housing body  11  and a housing collar  12 . The housing body  11  is designed to receive the sensor. The housing body  11  enables the sensor to analyze a process medium through the process inlet  2 . If the sensor is, for example, an inductive conductivity sensor, the measuring coils of the inductive conductivity sensor are enclosed by the housing body  11  and can thus be immersed into the process medium, for example, a liquid. In the case of an optical sensor, the housing body  11  enables the sensor, for example, to have only optical access to the process medium. 
     The housing collar  12  extends around the housing body  11  as shown in  FIGS.  1 - 7   . The housing collar  12  has a first sealing section  13  at a periphery of the housing body  11 . The first sealing section  13  is configured for receiving the process seal  3  to connect the process inlet  2  to the housing collar  12  in a fluid-tight manner (e.g., liquid-tight or air-tight). The housing collar  12  is designed in such a way that the first sealing section  13  seats on the process seal  3  when the process connection is fastened to the process inlet  2 . 
     The housing collar  12  extends from the housing body  11 . In one embodiment, the housing collar  12  has a thickness between 2 mm and 3.1 mm. This makes it possible to save material on the sensor housing  10 . The material thickness of the housing collar  11  is selected depending on the preferred manufacturing method to achieve a desired quality and/or a desired cost saving. 
     The housing collar  12  has a contact area  14 . The contact area  14  is configured for experiencing a contact force so that the sensor housing  10  is pressed onto the process seal  3 . 
     The housing collar  12  is formed integrally with the housing body  11 . Sealing points in addition to the process seal  3  are thus not needed. 
     The clamping element  20  of the process connection  1  has a contact area  22 , as shown in  FIG.  1   . The contact area  22  is configured for contacting the contact area  14  of the housing collar  12  in order to press the housing collar  12  onto the process seal  3 . 
     As shown in  FIG.  3   , the clamping element  20  is partially enclosed by two potential leakage paths L 1 , L 2 . The first leakage path L 1  is harmless for a sensor arranged in the process connection  1  since the leakage path L 1  cannot penetrate into the interior of the process connection  1 . The second leakage path L 2  is potentially harmful for a sensor arranged in the process connection  1  since the second leakage path L 2  does penetrate into the interior of the process connection  1 . 
     The clamping element  20  is annular in that the clamping element  20  forms a closed ring. The radial cross-section of the annular clamping element  20  can take any form. 
     The clamping element  20  has an axially circumferential first sealing section  21  and an axially circumferential second sealing section  23  (see  FIG.  3   ). 
     The first sealing section  21  is configured for contacting the process seal  3  in order to connect the process inlet  1  to the clamping element  20  in a fluid-tight manner. Due to the circumferential first sealing section  21  of the clamping element  20 , the clamping element  20  also comes into contact with the process seal  3  in addition to the sensor housing  10  and thus forms a further sealing point between the interior and exterior of the process seal  3  so that a sealing effect between the housing collar  12  and the clamping element  20  is achieved only with the already required process seal  3 . 
     In an alternative embodiment (see  FIG.  7   ), the clamping element  20  does not touch the process seal  3 . 
     The second sealing section  23  is configured for contacting an annular sealing element  15 . The annular sealing element  15  is disposed between the sensor housing  10  and the second sealing section  23  of the clamping element  20  (see  FIGS.  2 - 4   ). The potential second leakage path L 2  of the process medium between the clamping element  20  and the sensor housing  10  is thus sealed. The process medium thus cannot penetrate into the interior of the sensor housing  10  when the process seal  3  fails. 
     In one embodiment (not shown), the clamping element  20  has a leakage hole. The leakage hole is arranged between the first sealing section  21  and the second sealing section  23  of the clamping element in such a way that a process medium flowing along the second leakage path L 2  is at least partially discharged through the leakage hole. The leakage hole is configured for making visible to a user the discharge of the process medium along the potential second leakage path L 2 . 
     The annular sealing element  15  is arranged, for example, between the clamping element  20  and the housing body  11 , as shown in  FIGS.  2 - 4   . The annular sealing element  15  may have various cross-sectional shapes. For example, the annular sealing element  15  may be an O-ring seal. The clamping element  20  is designed to precisely fit the housing body  11 . The sensor housing  10  has a second sealing section  17  disposed on the housing body  11  in order to come into contact with the sealing element  15 . The sealing element  15  may be, for example, an elastomer seal. 
     Alternatively, the sealing element  15 , the second sealing section  23  of the clamping element  20 , and the second sealing section  17  of the sensor housing  10  can be arranged such that the sealing point formed by the sealing element  15  is formed between the clamping element  20  and the housing collar  12  of the sensor housing  10  (not shown). 
     As shown in  FIG.  4   , in an alternative embodiment of the process connection  1 , the first sealing section  13  of the housing collar  12  is arranged on an end face  18  of the housing collar  12 . The end face  18  of the housing collar  12  is located at a radially outer end of the annular housing collar  12 . 
     The first sealing section  13  of the housing collar  12  may have various cross-sectional shapes. For example, the first sealing section  13  may be flat or may be a groove (e.g., semicircular or rectangular). The process connection  1  is thus suitable, for example, for process inlets  2  that satisfy the requirements of SMS 1147, DIN 11851 or ISO 2852. 
     The sensor housing  10  has a transition region  16  which is arranged between the housing collar  12  and the housing body  11  and has a radius between 3.2 mm and 6 mm or greater than 6 mm, which can be seen particularly well in  FIG.  3   . Alternatively, the transition region  16  has a radius greater than 6 mm. This allows the process connection  1  to be less susceptible to deposits of the process medium. The hygienic properties of the process connection  1  are thereby improved. 
     The manufacturing method of the above-described process connection  1  according to the present disclosure is now described below. 
     In a first step, the sensor housing  10  is manufactured. During this manufacturing step, the housing body  11  and the housing collar  12  are integrally formed. Manufacturing the housing body  11  and the housing collar  12  as a single piece prevents gap formations at the process connection and avoids additional sealing points. 
     The sensor housing  10  can be manufactured in such a way that the housing collar  12  has an outer diameter D (as shown in  FIG.  1   ) such that the sensor housing  10  is larger than the largest process inlet  2  of a category of process inlets. Only a single “standard contour” of the sensor housing  10  thus needs to be manufactured for a plurality of process inlets, which reduces manufacturing costs and non-productive times. 
     The sensor housing  10  may be manufactured by a primary forming method (e.g., casting), a forming method (e.g., pressure forming), a cutting method (e.g., machining), or combinations of the aforementioned methods. 
     In order to manufacture the sensor housing  10 , for example, a material may be selected from one of the following materials: thermoplastics, thermosets, polyether ether ketones, thermoplastic polyether ether ketones, metal, ceramic or glass. 
     The sensor housing  10  is manufactured by an injection molding method, for example. This has the advantage that identical parts can be manufactured cost-effectively in large numbers and closed sensor housings can be produced in a hygienic design with a high degree of freedom of shape. Furthermore, a closed, seal-free surface can thus be realized with a high degree of freedom of design. 
     In a next step, the housing collar  12  is adapted in such a way that the housing collar  12  has an outer diameter D, which is configured for a prespecified process inlet  2 . This makes it possible to adapt the standard type of sensor housing to a particular process inlet  2  in order to achieve the maximum precision for the process connection  1 . If the housing collar  12  is to be adapted to the largest process inlet  2  of a category of process inlets, the adaptation step serves to achieve a higher accuracy of fit for the process inlet. 
     As shown in  FIGS.  5 - 7   , the adaptation step of the housing collar  12  also comprises the adaptation of the first sealing section  13  of the sensor housing  10  so that the sealing section  13  is configured for receiving a particular process seal  3 . The sealing section  13  is, for example, flat, conical or groove-shaped, semicircular or rectangular. 
     For example, during the adaptation step, the first sealing section  13  may be formed such that a molded seal in accordance with ISO 2852 may be received by the first sealing section  13  (see  FIG.  5   ). 
     For example, during the adaptation step, the first sealing section  13  may be formed such that a flat ring seal in accordance with SMS 1147 may be received by the first sealing section  13  (see  FIG.  6   ). 
     As a further example, during the adaptation step, the first sealing section  13  may be formed such that a D-ring seal in accordance with DIN 11851 may be received by the first sealing section  13  (see  FIG.  7   ). 
     The adaptation step of the housing collar  12  takes place, for example, by machining the housing collar  12 . This has the advantage of a high degree of flexibility in material and geometry coupled with a higher precision. 
     In a further step, the clamping element  20  is manufactured. The clamping element  20  is manufactured in such a way that it is configured for the sensor housing  10  for the particular process inlet  2 . 
     The clamping element  20  may be manufactured by a primary forming method (e.g., casting), a forming method (e.g., pressure forming), a cutting method (e.g., machining), or combinations of the aforementioned methods. The manufacturing method for the clamping element  20  can also be selected depending on the manufacturing method selected for the sensor housing  10 . 
     For manufacturing the clamping element  20 , a material is, for example, selected from one of the following materials: thermoplastics, thermosets, polyether ether ketones, thermoplastic polyether ether ketones, metal, ceramic or glass. 
     The clamping element  20  is fabricated, for example, by a machining process. This has the advantage that a flexible, requirement-appropriate selection of the material of the clamping element  20  and a high precision in the manufacture of the clamping element  20  are achieved at a favorable cost.