Cable feedthrough

Abstract

A cable feedthrough, designed for pressure-tight feedthrough of a cable through a housing wall, in particular of a sensor housing of a measuring probe, comprising a serrated ring that is pressed against a spring element in order to preload the spring element.

Description

[0001] Cable entry

[0002] Reference to related applications

[0003] This application claims priority from German patent application No. 10 2023 205 726.3, filed on June 19, 2023, which is incorporated in its entirety by reference into this document.

[0004] Technical area

[0005] The present invention relates to a cable bushing designed for the pressure-tight passage of a cable through a wall of a sensor housing of a measuring probe. Furthermore, the present invention relates to a measuring probe for process automation in industrial or private environments, which has such a cable bushing, and to the use of such a cable bushing for a measuring probe, in particular for a pressure measuring probe.

[0006] background

[0007] In the field of process automation in industrial or private environments, measuring probes are used, for example, pressure measuring probes that are inserted into a container on a cable. The cable serves to electrically connect the measuring probes and mechanically secure them. Cables with an external metallic shield, e.g., enclosed in a plastic, are particularly suitable for this purpose. Power and / or signal lines can then be routed to the probe inside the shield, protected from external influences.

[0008] The cable leads from the probe out of the container to a higher-level unit, such as a power supply and / or further electronics. One application is level measurement using a pressure probe. The pressure probe is inserted into a container filled with a medium by means of the cable. The pressure measured by the pressure probe corresponds to the height of the medium column above the pressure probe and is therefore a measure of the level in the container.

[0009] In these applications, a cable entry may be required to seal the downstream electronics and / or higher-level unit. This cable entry has a housing through which the cable is routed. The housing can be part of the higher-level unit and / or part of a mounting device for the probe, for example, by mounting the housing at the measuring point, e.g., on a container, using a flange or thread.

[0010] Likewise, the cable entry can be arranged on the probe and connected, for example, to the probe or a probe housing (hereinafter also referred to as the sensor housing) and ensure that no filling material penetrates into the probe.

[0011] Summary

[0012] It is an object of the present disclosure to provide a cable feedthrough for pressure-tight passage of a cable through a wall of a sensor housing of a measuring probe, which is characterized by a simple structure and good sealing effect.

[0013] This problem is solved by the features of the independent patent claims. Further developments of the invention are set out in the subclaims.

[0014] A first aspect of the present disclosure relates to a cable feedthrough configured for pressure-tight passage of a cable through a wall of a sensor housing of a measuring probe. The cable feedthrough comprises a housing with an opening configured for passing the cable into the interior of the housing. The housing of the cable feedthrough and the sensor housing may be the same housing and, in particular, constructed in one piece. However, it is also possible for the sensor housing to be detachably connected to the housing of the cable feedthrough, for example, they are screwed together, for example, by means of a screwable plug connection.

[0015] The cable entry has a molded seal inside the housing, located in the area in front of the opening to ensure pressure-tight cable passage. A spring element is provided, which is configured to exert a spring force on the molded seal in order to press the molded seal toward the opening by exerting a compressive force. To preload the spring element, a serrated ring or the like is provided, which is pressed against the spring element, thus being located on the opposite side of the molded seal compared to the housing opening.

[0016] According to one embodiment of the present disclosure, the housing tapers in the area of ​​the opening so that the molded seal can be easily pressed.

[0017] According to a further embodiment of the present disclosure, the housing is constructed in one piece. An interface to the sensor housing of the measuring probe can be provided at the end opposite the opening, or the measuring probe can be located in the housing of the cable feedthrough, for example, at this very end.

[0018] According to a further embodiment of the present disclosure, the housing is tubular, resulting in particular in low manufacturing costs and high stability.

[0019] According to a further embodiment of the present disclosure, the serrated ring has a plug-in tongue for contacting the cable.

[0020] The term "pronged ring" refers to a retaining element that rests against the inside of the housing wall and is frictionally connected to it, allowing it to exert the required pressure on the spring element. This refers to mechanical means that fulfill this function, such as a pronged ring. However, other solutions are also possible that allow this retaining element to be spread or wedged against the inside of the housing wall. The pronged ring represents only one simple way to provide this function. Therefore, the term "pronged ring" should be interpreted broadly.

[0021] According to a further aspect of the present disclosure, a measuring probe is provided, configured for process automation in an industrial or private environment, which comprises a sensor unit with a sensor housing, a cable configured to connect the sensor unit to a power supply and / or an evaluation unit located outside the measuring probe, and the cable feedthrough described above and below.

[0022] The sensor housing can be integrally connected to the cable entry housing or the sensor unit can be located in the cable entry housing.

[0023] For example, the measuring probe is a pressure measuring probe.

[0024] The term "process automation in industrial environments" can be understood as a branch of technology that includes measures for operating machines and systems without human intervention. One goal of process automation is to automate the interaction of individual components of a plant in the chemical, food, pharmaceutical, petroleum, paper, cement, shipping, or mining industries. A variety of sensors can be used for this purpose, which are specifically adapted to the specific requirements of the process industry, such as mechanical stability, insensitivity to contamination, extreme temperatures, and extreme pressures. Measured values ​​from these sensors are usually transmitted to a control room, where process parameters such as fill level, limit level, flow rate, pressure, or density are monitored, and settings for the entire plant can be changed manually or automatically.

[0025] A sub-area of ​​process automation in the industrial environment concerns the logistics automation of plants and the logistics automation of supply chains. With the help of distance and angle sensors, processes inside or outside a building, or within a single logistics facility, are automated in the field of logistics automation. Typical applications for logistics automation systems include baggage and freight handling at airports, traffic monitoring (toll systems), retail, parcel distribution, and building security (access control). What the aforementioned examples have in common is that the respective application requires presence detection in combination with precise measurement of the size and location of an object.For this purpose, sensors based on optical measuring methods using lasers, LEDs, 2D cameras or 3D cameras that measure distances according to the time of flight (ToF) principle can be used.

[0026] Another sub-area of ​​process automation in the industrial environment concerns factory-to-production automation. Applications for this can be found in a wide variety of industries, such as automotive manufacturing, food production, the pharmaceutical industry, and packaging in general. The goal of factory automation is to automate the production of goods using machines, production lines, and / or robots, i.e., to run the process without human intervention. The sensors used here and the specific requirements regarding measurement accuracy for detecting the position and size of an object are comparable to those in the previous example of logistics automation.

[0027] The terms used in the claims should be construed to give them the broadest possible reasonable interpretation consistent with the foregoing description. For example, the use of the article "a" or "the" in introducing an element should not be construed to exclude a plurality of elements. Similarly, the mention of "or" should be construed to include a plurality of elements, so that the mention of "A or B" does not exclude "A and B" unless it is clear from the context or the preceding description that only one of A and B is intended.Furthermore, the phrase "at least one of A, B, and C" should be understood as one or more elements from a group of elements consisting of A, B, and C, and should not be interpreted as requiring at least one of each of the listed elements A, B, and C, whether A, B, and C are related as categories or otherwise. Furthermore, the reference to "A, B, and / or C" or "at least one of A, B, or C" should be interpreted to include each individual unit of the listed elements, e.g., A, each subset of the listed elements, e.g., A and B, or the entire list of elements A, B, and C.

[0028] A further aspect of the present disclosure relates to the use of a cable feedthrough described above and below for a measuring probe, in particular for a pressure measuring probe.

[0029] Further embodiments of the present disclosure are described below with reference to the figures. Where the same reference numerals are used in the following description of the figures, they denote identical or similar elements. The representations in the figures are schematic and not to scale.

[0030] Short description of the characters

[0031] Fig. 1 shows a cable bushing with a measuring probe according to a

[0032] Embodiment.

[0033] Fig. 2 shows a cross-sectional view of a cable bushing according to an embodiment.

[0034] Fig. 3 shows a serrated ring according to one embodiment.

[0035] Detailed description of embodiments

[0036] Fig. 1 shows a cable bushing 100, at the end of which is a measuring probe 200. At the other end, an outlet opening is provided through which the cable 101 is passed.

[0037] Fig. 2 shows a cross-sectional view of a cable bushing 100, designed for the pressure-tight passage of a cable 101 through the wall of the housing 102 of the cable bushing. The cable 101 has one or more wires 109, as well as a ground connection 110, and a plastic sheath. The ground connection 110 is connected at its end 111 to the plug-in tongue 106 of the serrated ring 105. The serrated ring 105 wedges against the inner wall of the housing 102 so that it cannot slip. In doing so, it presses against the spring element 106. A disk 107 can be located between the spring element 106 and the serrated ring 105. In turn, the spring element 106 presses against the molded seal 104, which is located at the tapered end of the housing 102, and thus presses against the cable 101 to achieve a good sealing effect.A disc 108 can also be arranged between the molded seal 104 and the spring element 106 to evenly distribute the pressure across the molded seal 104. The cable 101 exits the cable gland 100 through the opening 103 at the tapered end.

[0038] To compensate for the diminishing sealing effect on the cable 101 or the housing 102 due to aging, the clamped molded seal 104, which can be made of an elastomer, is pressed against it by the spring element 106, for example a compression spring, in addition to its own restoring force. To enable the compression spring to transmit force, the preload is generated via the serrated ring 105. A multi-part design of the housing 102 using a threaded connection is not necessary. Also, no forming (flanging) is required. Since the housing does not have to be plastically formed to achieve the contact pressure (and thus a sealing effect), the manufacturing effort is reduced. Additionally, encapsulation can, but does not have to, be provided to further increase the sealing effect.

[0039] The housing 102 can be designed as a one-piece housing tube with the function of a sealing area and a potting area. Assembly is performed in the figure from the left side of the housing, i.e., the side with the larger opening, by sliding all components toward the smaller opening 103.

[0040] The components formed seal 104, spring element 106, and, if required, two support discs 107, 108 are inserted or pressed into the tube 102 together with the serrated ring 105. The serrated ring 105 is mounted so that the smaller diameter portion is inserted into the tube first. The two discs 107, 108 are not essential for the function, but serve to improve and more even force transmission to the formed seal 104 when a spiral compression spring is used.

[0041] Once the serrated ring 105 is inserted into the pipe 102 and the serrations are in contact with the inner diameter, the angled serrations ensure frictional adhesion to the pipe's inner surface. The serrated ring 105 can now only be moved in the direction of the molded seal 104.

[0042] There are several options for assembly with a specific spring preload on the molded seal 104. For example, a punch can be used to compress the spring element 106 to a defined extent. Alternatively, a force-controlled press can be used, with which the desired pressing force can be adjusted.

[0043] The serrated ring 105 prevents the molded seal 104 from retracting and relaxing. Depending on the dimensions of the serrated ring 105, a force of 800 Newtons can be withstood with a nominal diameter of 20 mm. A special shape of the serrated ring 105, e.g., with a plug-in tongue 106, also provides the possibility of contact between the cable 101 and the housing 102 for electrical purposes, e.g., for shielding or grounding.

[0044] The housing 102 can, in particular, be constructed in one piece and have a potting area. A multi-part housing is not required, and thus, there is no need for a connection process using a thread with a seal or welding of the two housing parts.

Claims

Patent claims 1. A cable feedthrough (100) configured for the pressure-tight passage of a cable (101) through a wall of a housing, in particular a sensor housing of a measuring probe (200), comprising: a housing (102) with an opening (103) configured for the passage of the cable; a molded seal (104) inside the housing in the region in front of the opening to provide the pressure-tight passage of the cable; a spring element (106) configured to exert a spring force on the molded seal to press the molded seal towards the opening; a serrated ring (105) pressed against the spring element to preload the spring element.

2. Cable bushing (100) according to claim 1, wherein the housing (102) tapers in the area in front of the opening (103) 3. Cable bushing (100) according to claim 1 or 2, wherein the housing (102) is made in one piece.

4. Cable bushing (100) according to one of the preceding claims, wherein the housing is tubular.

5. Cable bushing (100) according to one of the preceding claims, wherein the toothed ring (105) has a plug-in tongue (106) for contacting the cable.

6. A measuring probe (200) configured for process automation in an industrial or private environment, comprising: a sensor unit (201) with a sensor housing; a cable (101) configured for connecting the sensor unit to a power supply and / or an evaluation unit; a cable feedthrough (100) according to one of claims 1 to 5, configured for pressure-tight passage of the cable through a wall of the sensor housing.

7. Measuring probe (200) according to claim 6, wherein the measuring probe is a pressure measuring probe.

8. Use of a cable bushing (100) according to one of claims 1 to 5 for a measuring probe, in particular for a pressure measuring probe.

Images