Object end position sensor

Abstract

This utility model relates to devices for monitoring the position of moving parts of mechanisms, in particular for monitoring the opening of manhole covers in accordance with GOST 3634-2019, installed in manholes in accordance with GOST 8020-2016. The technical result of improving the end-of-life sensor is a reduction in metal consumption and manufacturing labor while maintaining functionality.The technical result is achieved in that in the object limit position sensor, comprising a non-magnetic housing, a reed switch with a unit for electrically connecting it to the cores of the alarm cable, introduced into the housing through a cable entry, and a spring-loaded rod with a permanent magnet, the housing is made of two mechanically fastened pipes, one of the ends of the first pipe is plugged, a cable entry is installed in the second end by a thread, and a reed switch with a unit for electrically connecting it to the cores of the alarm cable is placed in the internal cavity, a spring-loaded rod with a permanent magnet is placed in the second pipe, mated with its internal diameter by a sliding fit through two rings secured at its ends. 7 c.p. phyl., 5 fig.

Description

[0001] The utility model relates to devices for monitoring the positions of moving parts of mechanisms, in particular for monitoring the opening of hatch covers in accordance with GOST 3634-2019, installed in wells in accordance with GOST 8020-2016.

[0002] The TERMINAL-M-LRW manhole opening sensor, manufactured by Novouchet in Kazan, is designed for remote monitoring of manhole cover openings. The sensor is mounted under the manhole cover on a flexible U-shaped bracket and is triggered by its limit switch when the cover is opened, generating a radio alarm. The sensor's limit switch is an electric contact microswitch that contacts the manhole cover via a movable rod equipped with a sealing gasket. The sensor's microswitch, with its electronic circuit, is housed in a housing with a cover and a cable entry (Novouchet LLC website: https: / / novouchet.ru / product / datchik-otkrytija-ljukov / ).The disadvantage of this sensor is its low degree of protection against water (IP), due to the presence of an electrical contact microswitch in the design, which operates unstable in conditions of low temperatures and high humidity, which gets to the microswitch through the connection of the moving rod with the housing and the extended seal of the housing cover.

[0003] A similar manhole cover opening sensor, the DL-108, is known. It features a self-powered battery and radio data transmission for remotely monitoring manhole covers in real time. The sensor consists of a cylindrical housing with threaded covers fitted with elastic seals. Inside the housing is a microswitch with an electronic circuit, which is activated by a moving rod whose other end contacts the monitored object. The sensor's water resistance is increased by using a bellows at the junction of the rod and the housing, and by using threaded covers with seals instead of rectangular ones (Glonass-Service website, St. Petersburg: https: / / glonasss.com / product / datchik-otkrytiya-kryshki-lyuka / ).A disadvantage of this sensor is its low IP rating, due to the presence of an electrical contact microswitch. This microswitch operates unstable in low temperatures and high humidity conditions. Humidity is generated by temperature fluctuations within the sensor housing (dew point changes) and is released when the sensor battery is replaced or its position is adjusted. Furthermore, reliable radio transmission is not always possible in dense industrial environments with industrial electromagnetic interference.

[0004] Explosion-proof limit switches are known, comprising a box-shaped housing with a rectangular cover, in the internal cavity of which an electric contact microswitch is placed, electrically connected to the wires of an external alarm cable, which is introduced into the cavity of the housing through a cable entry. A hole is made in the body of the housing, in which a spring-loaded rod moves, one end of which contacts the microswitch, and the other end directly or through a drive system contacts the controlled object, causing the microswitch to operate. To protect against dust and water, the rod is equipped with an elastic seal (Limit and travel switches in explosion-proof design of the KPV series. Operating Manual. SMD 642230, 480 000 RE https: / / smd-tlt.ru / image / tehndoc / manual / manual-pkv-vikluchateli.pdf).

[0005] A disadvantage of this sensor is its low water protection rating (IP), due to the presence of an electric contact microswitch in the design. This protection rating is unstable in low temperatures and high humidity. Humidity is generated by temperature fluctuations within the sensor housing and penetrates the housing during installation of the external alarm cable with the cable entry removed and the housing cover open, as well as through the seal of the sliding rod. The closest in purpose, technical essence, and achieved result to an object limit switch is the explosion-proof magnetic contact limit switch model KV-01, manufactured by ZAO "Tsentravtomatika" in Voronezh. Instead of an electric contact microswitch, as in similar limit switches, it uses a reed switch, which is more resistant to moisture and temperature.This switch comprises a rectangular non-magnetic housing with a cover, screwed together through an elastic seal. The housing interior houses a reed switch with an electrical connection for its terminals to the alarm cable cores, which is inserted into the housing through a threaded cable entry. A blind hole in the bottom of the housing houses a spring-loaded, two-stage cylindrical rod with a permanent magnet, which acts on the reed switch through the bottom of the non-magnetic housing, triggering it to operate at specific rod positions. The electrical connection for the reed switch terminals to the alarm cable cores is a printed circuit board with terminal blocks.The solid-machined two-stage rod with magnet is secured to the housing using a nut with a sealing ring at the smaller diameter stage of the rod, while the spring is located between the bottom of the housing's blind hole and the inner end of the rod at its larger diameter. The rod's measuring tip is formed by rounding the end of the smaller diameter rod (Fig. A2 of the manual). The limit switch is secured to the supporting surface using a separate L-shaped bracket (angle) with M3 screws in the corresponding threaded holes in the bottom of the housing (Fig. A1 of the manual). The design of the KV-01 limit switch provides protection against dust and water IP65 according to GOST 14254-2015 (IEC60529-2013) in the temperature range from minus 60 to plus 60°C (LIMIT SWITCHES KV. OPERATION MANUAL TsKLG.642251.005 RE https: / / www.centravtomat.ru / 2support / 2_1_doc / kv_re.pdf).A disadvantage of the KV-01 limit switch is its high metal content and labor intensity. The box-shaped switch housing and cover are machined, milled, and drilled from a single piece. This requires a thicker bottom to accommodate a blind hole for the magnet rod and threaded holes for attaching the mounting bracket. When using this type of enclosure for explosion-proof applications, the thickness of the enclosure and cover walls is significantly increased due to the requirements of GOST IEC 60079-1-2011 for the width of the enclosure walls and the end clearance between them. This prevents flames from escaping the enclosure in the event of a possible explosion of a hazardous mixture inside.In addition, the switch has insufficient protection against exposure to water under conditions of complete periodic flooding, due to the presence of an extended connection between the housing and the cover through an elastic seal, which requires a significant amount of compression force over its entire surface, and a blind hole for placing a movable rod with a magnet, into which moisture can enter and accumulate through the external elastic sealing ring, followed by its freezing.

[0006] The task solved by the object's end position sensor is to reduce the cost of its production and improve technical characteristics.

[0007] The technical result of improving the object's end position sensor is a reduction in metal consumption and labor intensity of manufacturing while maintaining functionality.

[0008] The specified technical result is achieved by the fact that in the sensor of the final positions of the object, containing a non-magnetic housing, a reed switch with a unit for its electrical connection to the cores of the alarm cable, introduced into the housing through a cable entry, and a spring-loaded rod with a permanent magnet, the housing is made of two mechanically fastened pipes, one of the ends of the first pipe is plugged, a cable entry is installed in the second end along a thread, and in the internal cavity a reed switch is placed with a unit for its electrical connection to the cores of the alarm cable, in the second pipe a spring-loaded rod with a permanent magnet is placed, mated with its internal diameter along a sliding fit through two rings secured at its ends.In addition, the rod is made of a pipe, fastened in its middle part with a washer of smaller outer diameter than the inner diameter of the second pipe, a spring is placed between the washer and one of the rings, a magnet is placed inside the rod, the magnet is fixed with a compound, one of the pipes is fastened to a mounting bracket having a supporting surface for mounting the sensor on a plane or a curved surface, the axes of the pipes are parallel, the axes of the pipes are perpendicular, one of the rings is made removable, at least one of the rings is made with through holes or grooves, the rings are equipped with an elastic rod seal.

[0009] Making the housing from two non-magnetic tubes mechanically fastened together, such as by welding, significantly reduces the metal content and manufacturing labor by eliminating the need to fabricate a hollow housing from a solid rectangular blank. This also reduces the housing wall thickness while maintaining its strength and impact resistance. The use of mass-produced tubes significantly reduces the cost of housing materials and the labor required for its manufacture. This allows for the rapid creation of sensors with varying chemical resistance to external influences due to the wide range of tubes available, such as stainless steel, titanium, brass, and others. The absence of an extended elastic seal between the cover and housing increases the sensor's resistance to external liquids and dusty environments.By making one of the ends of the first pipe plugged and installing a fixed, certified cable entry with its own elastic seals into its second end via a thread with a standardized torque, the cable entry forms a sealed internal cavity of the first pipe, where moisture-sensitive electrical connections are located, namely: the terminals of the reed switch with the unit of their electrical connection with the cores of the external alarm cable, which ensures the operability of the sensor under increased external influences of liquid, including its flooding.

[0010] Placing a spring-loaded rod with a permanent magnet in a second non-magnetic tube reduces the requirements for its tightness and the tightness of the entire sensor under external influences, due to the absence of electrical connections in it.

[0011] The sliding fit of the rod's outer surface to the second pipe's inner diameter through two rings secured to its ends, at least one of which is removable, ensures reliable, coaxial, and unambiguous movement of the rod and, consequently, the magnet relative to the second pipe's surface, even under parasitic radial forces acting on the rod's end. This ensures not only the entry but also the exit of fluid from the second pipe, especially when it is positioned vertically on the monitored object and the gap with the rod is provided by at least one larger ring. The removable design of one of the rings allows for assembly / disassembly of the entire sensor during manufacturing and repair, as well as maintenance (cleaning) of the second pipe by unqualified personnel without access to the sensor's electrical connections.

[0012] Making the rod from a pipe, fastened in its middle part with a washer, smaller in outer diameter than the inner diameter of the second pipe, allows for the installation of a rod spring between it and one of the end rings of the second pipe, which eliminates the need for a technologically complex blind hole and allows for the use of either a compression spring or an extension spring, depending on the task being solved by the sensor, taking into account its dimensions.

[0013] The placement of the magnet inside the tubular rod with the ability to install it in a specific position allows for the rapid adjustment of the sensor response moment during assembly, taking into account actual deviations from the nominal characteristics of the reed switch and magnet, by moving it in the rod, and protecting the magnet from impacts at the end positions of the rod, compared to the design of the sensor with an external ring magnet on the rod.

[0014] Fixing the position of the magnet in the rod with a compound allows for a technologically simple, shock-resistant and hermetic connection with the inner surface of the rod.

[0015] Fastening one of the pipes to a mounting bracket that has a supporting surface with holes for attaching the sensor to a plane or a round supporting surface allows you to immediately obtain a finished product ready for installation on the project site and change the height of the axis of the rod movement relative to the supporting plane or surface of the controlled object of a specific sensor model within the diameter of the pipes during the manufacture of the sensor by changing the fastening of the same bracket to one or another pipe.

[0016] The design of the sensor, in which the axes of the two pipes are parallel, allows for the technologically simple fastening of non-magnetic pipes directly, for example, by tack welding in the area of ​​their ends, without disrupting the magnetic conductivity of the middle sections of the pipes.

[0017] By connecting two pipes so that their axes are perpendicular, it is possible to create a sensor with an angular cable entry branch perpendicular to the rod's movement trajectory. This is important when installing the sensor in confined spaces during monitoring, particularly when using rigid alarm cables, as well as cables laid in pipes or metal sleeves that have a significant allowable bending radius.

[0018] In the sensor design version, when one or two of its rings are made with through holes or grooves, which, together with the gap between the washer on the rod and the inner diameter of the second pipe, makes it possible to create a “partially leaky (IP X0)” sensor while maintaining resistance to liquid exposure (IP 68) for the entire sensor, in which external liquid not only enters the internal cavity of the second pipe, but also flows out of it, which allows maintaining the operability of the sensor in conditions of liquid freezing.

[0019] The sensor version, when its rings are equipped with an elastic rod seal, allows the creation of a sensor for the technological needs of industrial automation in conditions of strong dust formation at the control object.

[0020] Examples of possible implementation of the claimed object end position sensor are explained by drawings.

[0021] Fig. 1 shows a general view with local sections of the sensor in the embodiment where the axes of the two pipes that form its body are parallel, and the plane passing through their axes is parallel to the supporting surface of the bracket.

[0022] Fig. 2 shows a view of the sensor in a version where the axes of the two pipes forming the body are parallel, and the plane passing through their axes is perpendicular to the supporting surface of the bracket.

[0023] Fig. 3 shows a view of the sensor in the embodiment where the axes of the two pipes forming the body are perpendicular.

[0024] Fig. 4 shows view B of Fig. 1 in the embodiment of sensor rings with through holes.

[0025] Fig. 5 shows section B-B of Fig. 2 in the embodiment of the sensor ring with an elastic rod seal.

[0026] The object end position sensor comprises a first non-magnetic tube 1, fastened, for example, by tack welding 2, to a second non-magnetic tube 3 at their ends, forming the sensor housing. Tubes 1 and 3 can also be fastened via a shaped mounting bracket similar in design to Fig. 3. For example, stainless steel pipes 12Kh18N10T according to GOST 9941-91 can be used as pipes, and welding is performed according to GOST 16037-80 with a type U 17 seam. Pipe 1 has one plugged end, made, for example, by rolling or welding a separate bottom, and a thread is cut along the internal diameter at the other end of pipe 1 for installing a certified cable entry 4 with a sealing ring 5, for example, manufactured by Block LLC http: / / block-ex.ru / or Atex Electro LLC atelex.ru, providing IP68 protection from dust and water according to GOST 14254-2015.Cable gland 4 is selected from the range of manufactured cable glands for the required alarm cable 6 at a given specific facility based on the diameter of its belt insulation and the method of installation at the facility (open, in a pipe, in a metal sleeve). The cores 7 of the alarm cable 6 are electrically connected to the terminals of the reed switch 8 via its electrical connection unit 9. The other end of the alarm cable 6 is connected to the control device of the facility (not shown in the drawing). The electrical connection unit 9, depending on the sensor version, can be made of various designs, namely: in the case of a sensor manufactured with a permanently connected specific alarm cable 6 (the manufacturer's cable), its cores 7 are soldered to the terminals of the reed switch 8 and dielectrically insulated, for example, with heat-shrinkable tubing of the TNTng-LS type from the KVT plant with an insulation strength of 15 kV / mm or insulated sleeves of the GSI-T type according to GOST 23469.3-79, etc.(not shown in the drawing), in case of manufacturing the sensor with electrical connection to cable cores of different brands (customer's cable), reed switch 8 is mounted on a printed circuit board with soldered terminals, for example, Wago terminals of the 2060 and 2061 series (shown conditionally in the drawing). The inner cavity of pipe 1 or a part thereof can be filled with a dielectric compound to increase vibration resistance, for example, of the ED-20, Viksint PK68A, PentElas 711 type, or placed in a dielectric cap forming double insulation in accordance with the requirements of clause 15.2 of GOST 31610.0 (not shown in the drawing). Note: in case of manufacturing the sensor in explosion-proof design, depending on the required dimensions of the sensor and the technological capabilities of the manufacturer, the design of pipe 1 can be made in accordance with Russian Federation patents No. 123219, 190447, 208340.

[0027] Pipe 3 contains rod 10, made of a non-magnetic pipe, such as stainless steel, with measuring tip 11, which can be fastened to rod 10 by welding or threading with a thread locking compound, such as Anaerobe 304 TU 20.30.22-001-06533594-2017, manufactured by Burkraft LLC. The shape of tip 11 may vary depending on the trajectory of movement and the shape of the test object: spherical, roller, or with a roller drive, for example, as shown in Fig. B1, taken as the prototype of the KV-01 limit switch. A stepped washer 12 is fixedly secured in the middle section of rod 10, for example by welding. Its outer diameter is smaller than the inner diameter of pipe 3, and its surface facing tip 11 can be conical with through holes or grooves for fluid drainage (not shown in the drawing). Rings 13 and 14, whose inner diameters are coaxial, are mounted on the two ends of pipe 3.At least one of the rings is removable, for example, ring 13, threaded into the interior of pipe 3. The other ring, 14, can be a permanent, two-stage design and welded into pipe 3. Rings 13 and 14 form a sliding fit with stem 10 with a clearance. This, together with washer 12, allows any liquid trapped inside pipe 3 to drain, especially when the sensor is installed vertically. Between the non-removable ring 14 and the washer 12, there is a compression spring 15, which is centered with its internal diameter in the pipe 3 on the smaller diameter steps of the washer 12 and the non-removable ring 14. It is also possible to install an extension spring between the washer 12 and the removable ring 13. One of the pipes, for example, pipe 1, is mechanically fastened, for example, by welding, to a mounting bracket 16, which has a supporting surface 17 with holes 18 for mounting the sensor on flat or curved surfaces of the test object; the bracket 16 can also be equipped with an external grounding stud 19.The mounting bracket 16 may be made in the form of a flat plate, for example, according to Russian patent No. 123219, or U-shaped with segmented cutouts according to Russian patent No. 197572. A permanent cylindrical magnet 20 is placed inside the rod 10 and is fixed with compound 21. Fig. 3 shows a variant of angular fastening of pipes 1 and 3 through a shaped square bracket 22 with segmented cutouts of different heights, orienting pipes 1 and 3 perpendicular to each other. It should be noted that fastening pipes 1 and 3 in Figs. 1 and 2 is also possible by using similar shaped brackets of different heights, and not only directly along their outer surfaces. In the variant of execution of pipe 3 of the sensor (Fig.4) to control the opening of the hatch of periodically flooded wells in the cold season, to improve the flow of non-magnetic liquid from the pipe 3, small through holes or grooves 23 can be made in the non-removable lower ring 14, or the sliding fit of the rod 10 in the non-removable ring 14 can be made with a larger gap than in the removable ring 13. In the embodiment of the pipe 3 of the sensor (Fig. 5) with increased protection from dust and moisture, for example, for monitoring in dusty rooms, grooves can be made in the rings 13 and 14 along their inner diameter, into which sealing rings 24 are installed, for example, according to GOST 9833-73, contacting with the outer diameter of the rod 10. The sensor is assembled as follows. At the manufacturer's technological stand (not shown in the drawing), the electrical connection of the reed switch 8 is made via its electrical connection unit 9 to a control device, for example, an ohmmeter.By moving the magnet 20 along the internal cavity of the rod 10 with the positions of the rod 10 fixed, its location is determined, corresponding to the standardized technical characteristics of the sensor, taking into account the deviations of the characteristics of the actual magnet 20 and the reed switch 8 from the nominal ones, after which the location of the magnet 20 in the rod 10 is fixed with compound 21.

[0028] The installation and maintenance of the sensor on the monitored object is carried out as follows. The sensor is secured by means of mounting bracket 16 or 23, through openings 18 on the monitored object in such a way that the movement of the movable part of the object (hatch cover) contacts tip 11, and the stroke of rod 10 causes the actuation of reed switch 8, but does not compress spring 15 to the stop. In cases where the coaxial mounting surfaces of bracket 16 of the sensor (the internal diameter of the hatch or concrete ring of the well) and the moving monitoring surface (hatch cover) differ significantly in diameter, bracket 16 is secured through an intermediate support (not shown in the drawing), for example, similar to the U-shaped support of the TERMINAL-M-LRW model hatch opening sensor. Unscrew cable entry 4 with sealing ring 5 from pipe 1 and put them on alarm cable 6. Strip cable 6 to its cores 7.The reed switch 8 is removed from the body of the pipe 1 together with its electrical connection unit 9 and electrically connected to the cores 7 of the cable 6. The reed switch 8 and its electrical connection unit 9 are inserted back into the pipe 1. The sealing ring 5 with the cable entry 4, previously placed on it, is moved along the alarm cable towards the end of the pipe 1 and, by sequentially tightening the components of the cable entry 4 with the standardized torque, the elastic seals of the ring 5 and the cable entry 4 are compressed, thereby obtaining a hermetic cavity of the pipe 1 up to IP68, depending on the characteristics and certificate for the cable entry 4.When the rod 10 moves, caused by the movement of the movable part of the controlled object (hatch cover) beyond the permissible values ​​(opening of the hatch cover), the spring-loaded rod 10 with the magnet 20 moves and the reed switch 8 is triggered by a change in the effect of the field of the permanent magnet 20 on it, which is recorded by an external device for monitoring the state of the object (not shown in the drawing), connected to the alarm cable 6. During technical maintenance of the sensor, the smooth movement of the rod 10, clogging of the pipe 3, the absence of damage to the internal parts are checked, for which purpose the removable ring 13 is unscrewed and the cavity and parts of the pipe 3 are inspected, without disassembling the pipe 1 with its electrical connections.

[0029] Thus, the design of the body of the object's end position sensor in the form of two mechanically fastened non-magnetic tubes allows for a reduction in the cost of manufacturing the sensor and an increase in its protection against the effects of liquids, as well as simplification of its maintenance.

Claims

1. A sensor for the final positions of an object, comprising a non-magnetic housing, a reed switch with a unit for its electrical connection to the cores of an alarm cable, introduced into the housing through a cable entry, and a spring-loaded rod with a permanent magnet, characterized in that the housing is made of two mechanically fastened pipes, one of the ends of the first pipe is plugged, a cable entry is installed in the second end by a thread, and a reed switch with a unit for its electrical connection to the cores of an alarm cable is placed in the internal cavity, a spring-loaded rod with a permanent magnet is placed in the second pipe, mated with its internal diameter by a sliding fit through two rings secured at its ends.

2. A sensor for the final positions of an object according to paragraph 1, characterized in that the rod is made from a pipe, fastened in its middle part to a washer, the outer diameter of which is smaller than the inner diameter of the second pipe.

3. A sensor for the final positions of an object according to paragraph 1, characterized in that one of the pipes is fastened to a mounting bracket having a support surface for fastening the sensor to a plane or curved surface.

4. A sensor for the final positions of an object according to paragraph 1, characterized in that the axes of the pipes are parallel.

5. A sensor for the final positions of an object according to paragraph 1, characterized in that the axes of the pipes are perpendicular.

6. A sensor for the final positions of an object according to paragraph 1, characterized in that one of the rings is removable.

7. A sensor for the final positions of an object according to paragraph 2, characterized in that the spring is placed between the washer and one of the rings.

8. The sensor for the final positions of an object according to paragraph 2, characterized in that the magnet is placed inside the rod and fixed with a compound.

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