Sealed passive proximity switch with permanent magnetic mechanism

Abstract

The invention relates to the technical field of manufacturing of proximity switches for the nuclear industry, in particular to a sealed passive proximity switch with a permanent magnetic mechanism, which comprises a shell, an execution mechanism, a first fastening nut, a sealed base and a cable outgoing line, and is characterized in that the upper end of the execution mechanism is connected with the bottom of the shell, and the lower end of the execution mechanism is connected with the fastening nut in a matched manner; the bottom of the fastening nut is connected with the sealing base in a matched mode, and the cable outgoing line is arranged at the bottom of the sealing base. Compared with the prior art, the contact system has the beneficial effects that the contact system not only has the characteristics of accurate induction action of an external magnetic object, high stability of the contact system and high sealing protection grade, but also has long-term contact stability under a severe environment condition, and realizes long-term reliable work of the whole machine.

Description

Technical Field

[0001] The invention relates to the technical field of manufacturing proximity switches for nuclear industry, in particular to a sealed passive proximity switch with a permanent magnet mechanism. Background Art

[0002] As the country pays more attention to environmental pollution and in the process of searching for alternative energy sources, people begin to pay more and more attention to the application of nuclear energy. The most important application of nuclear energy is power generation. Nuclear energy, a clean energy, will occupy a large market share in power generation. As the trend of localization becomes stronger, the existing proximity switches can no longer meet the needs of nuclear power sites.

[0003] In the prior art, proximity switches are prone to occasional poor contact, contact surface oxidation, normally closed contacts being disconnected and normally open contacts being unable to be reliably connected due to their structural characteristics. These switches are unable to reflect the actual operating conditions of the monitored objects inside a nuclear power plant and may result in switch misjudgment.

[0004] At the same time, the contact system cavity of this type of proximity switch is sealed with glue, which can only meet the IP60 protection requirements and can only prevent dust from entering. It cannot isolate the contact system contacts from contamination by moisture, salt spray, and hydrogen sulfide atmosphere, causing unstable contact and leading to switch misjudgment.

[0005] Therefore, a new sealed passive proximity switch with a permanent magnetic mechanism is needed to solve the above-mentioned problems. Summary of the invention

[0006] The purpose of the present invention is to solve the deficiencies in the prior art and to provide a proximity switch that can work reliably for a long time at high temperatures, can provide a stable holding force for the contact system, and can avoid poor contact of the contact system due to stress changes in elastic materials under harsh environmental conditions such as high temperature and strong vibration.

[0007] To achieve the above object, the present invention provides a sealed passive proximity switch structure with a permanent magnet mechanism, comprising:

[0008] A housing, an actuator, a first fastening nut, a sealing base and a cable lead, wherein the upper end of the actuator is connected to the bottom of the housing, the lower end of the actuator is matched with the fastening nut, the bottom of the fastening nut is matched with the sealing base, and the cable lead is arranged at the bottom of the sealing base;

[0009] The actuator includes a permanent magnet mechanism and a contact system, wherein the permanent magnet mechanism is arranged on the top of the contact system, and the permanent magnet mechanism includes:

[0010] An induction permanent magnet, a fixed permanent magnet, an action permanent magnet, an assembled moving contact, a gasket and a second fastening nut. The induction permanent magnet, the fixed permanent magnet and the action permanent magnet are connected in sequence from top to bottom. A moving contact is provided at the bottom of the action permanent magnet. The moving reed is provided on one side of the moving contact. The gasket is provided at the bottom of the moving reed and is connected to the moving contact through the second fastening nut.

[0011] The contact system comprises a contact system base and a dynamic spring assembly, wherein the contact system base is an injection molded body base, and the dynamic spring assembly comprises an upper static spring, a middle spring and a lower static spring, wherein the upper static spring and the lower static spring are matched and connected, and the bottom of the upper static spring and the top of the lower static spring are respectively provided with assembly static contacts, and the bottoms of the upper static spring, the middle spring and the lower static spring are all fixedly arranged on the surface of the injection molded body base;

[0012] When the proximity switch is in a non-operating state, the normally closed contact is closed. When the proximity switch is in an operating state, the movable reed assembly is disconnected from the normally closed contact and closed with the normally open contact.

[0013] Preferably, the induction permanent magnet comprises a first permanent magnet steel, the permanent magnet steel outer shell is provided with a fixing cover, and the fixing cover is cooperatively connected with the permanent magnet steel.

[0014] Preferably, the fixed permanent magnet includes a mounting cover and a second permanent magnet, the mounting cover is sleeved on the outside of the second permanent magnet, the top of the second permanent magnet is cooperatively connected with a third fastening nut, and the bottom of the second permanent magnet is sleeved with a guide column.

[0015] Preferably, the action permanent magnet comprises a connecting rod and a third permanent magnet, the bottom of the connecting rod is cooperatively connected with the top of the third permanent magnet, and the bottom of the third permanent magnet is cooperatively connected with the plastic-encapsulated body.

[0016] Preferably, the injection molded body base comprises a sealing bottom plate, a surface of the sealing bottom plate is provided with a plurality of lead pins, and the plurality of lead pins are respectively connected with glass insulators.

[0017] Preferably: the shell has a cavity chamber, the top of the cavity chamber is a closed end, the bottom of the cavity chamber is an open end, the open end is provided with internal threads and external threads, the internal threads are used to install the fastening nut for fastening, and the external threads are used to connect the gland or NPT connector.

[0018] Preferably, the first permanent magnet mechanism, the second permanent magnet mechanism and the third permanent magnet mechanism are made of samarium praseodymium cobalt rare earth materials.

[0019] Preferably, the movable spring assembly adopts a semicircular flexible contact structure.

[0020] Compared with the prior art, the technical solution proposed in this application has the following beneficial effects:

[0021] 1. The difficulty of assembling the proximity switch is reduced, and the adjustment and detection are simple and accurate. The key indicators such as sensing action distance, contact pressure, and action sensitivity are more accurately controlled;

[0022] 2. It can intuitively and accurately adjust and detect the contact pressure and contact surface to ensure contact stability; at the same time, the detection window can intuitively detect the sensitivity of the proximity switch by visual inspection, which improves the stability and reliability of the key technical indicators of the proximity switch;

[0023] 3. Design a permanent magnet mechanism consisting of three groups of permanent magnets, namely a fixed permanent magnet, an induction permanent magnet and an action permanent magnet. The permanent magnets used in the permanent magnet mechanism designed by the present invention can work reliably for a long time at high temperatures, can provide a stable holding force for the contact system, and avoid poor contact of the contact system due to stress changes in elastic materials under harsh environmental conditions such as high temperature and strong vibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0025] Figure 1 This is an overall structural diagram of the proximity switch of the present invention;

[0026] Figure 2 Another connection diagram of the proximity switch of the present invention;

[0027] Figure 3 It is a structural diagram of the actuator of the present invention;

[0028] Figure 4 It is a structural diagram of the permanent magnet mechanism of the present invention;

[0029] Figure 5 This is a structural diagram of a fixed permanent magnet of the present invention;

[0030] Figure 6 It is a structural diagram of the action permanent magnet of the present invention;

[0031] Figure 7 This is a structural diagram of the induction permanent magnet of the present invention;

[0032] Figure 8 is a structural diagram of the contact system of the present invention;

[0033] Fig. 9 It is the overall structure diagram of the contact system of the present invention;

[0034] Fig.10 It is a structural diagram of the contact system base of the present invention;

[0035] Fig.11 is a side view of the present invention;

[0036] Fig.12 This is a diagram of a non-working state of the proximity switch of the present invention;

[0037] Fig.13 This is a working state diagram of the proximity switch of the present invention.

[0038] In the figure: 1. housing, 2. actuator, 3. first fastening nut, 4. sealing base, 5. cable lead, 6. permanent magnet mechanism, 7. contact system, 8. induction permanent magnet, 9. fixed permanent magnet, 10. actuating magnet, 11. moving contact, 12. moving reed, 13. gasket, 14. second fastening nut, 15. third fastening nut, 16. second permanent magnet, 17. guide column, 18. mounting cover, 19. connecting rod, 20. third permanent magnet, 21. plastic package, 22. first permanent magnet mechanism, 23. fixed cover, 24. upper static reed, 25. static contact, 26. lower static reed, 27. middle reed, 28. injection molding base, 29. soft copper wire, 30. sealing bottom plate, 31. lead pin, 32. glass insulator. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe and discuss the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings of the present invention. Obviously, what is described here is only a part of the examples of the present invention, not all the examples. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0040] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may also be a component centered. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may also be a component centered. When a component is considered to be "set on" another component, it may be directly set on the other component or there may also be a component centered. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0042] The present invention discloses a sealed passive proximity switch structure with a permanent magnet mechanism, comprising a proximity switch housing 1, an actuator 2, a fastening nut 3, a sealing base 4, and a cable lead 5. Figure 1 shown.

[0043] The actuator includes a permanent magnet mechanism 6 and a contact system 7. Figure 3 As shown, the key technical indicators of the proximity switch, such as contact stability, action flexibility, and sensing distance, can all be accurately achieved on the actuator.

[0044] Adjustment and detection windows are designed at the contact position of the actuator housing to accurately adjust and detect the contact pressure and contact surface to ensure contact stability; the detection window can intuitively detect the sensitivity of the proximity switch action through visual inspection, thereby improving the stability and reliability of the proximity switch technical indicators.

[0045] The contact system-base is formed by high temperature resin injection molding of the upper static spring piece 24 for assembling the static contact 25, the lower static spring piece 26 for assembling the static contact 25, and the middle spring piece 27 into a base 28. The contact system-base is installed in the permanent magnet mechanism, and the moving spring piece assembly and the middle spring are welded and connected by soft copper wire 29. After the debugging and testing process is qualified, the fixing pin is installed.

[0046] Install the actuator into a special debugging fixture, adjust and detect the window on the actuator housing, accurately adjust and detect the contact pressure and contact surface to ensure contact stability; use a special dynamometer to detect the contact pressure in the detection window; use the magnetic detection body in the special magnetic test fixture to test key indicators such as sensing action distance and action sensitivity.

[0047] The key indicators of the original foreign proximity switches, such as sensing action distance, contact pressure, and action sensitivity, are to be assembled in a closed cavity, which is complex to assemble and difficult to detect.

[0048] The permanent magnet mechanism is composed of an induction permanent magnet 8, a fixed permanent magnet 9, an action permanent magnet 10, a moving reed 12 for assembling a moving contact 11, a gasket 13, and a fastening nut 14. Figure 4 shown.

[0049] The fixed permanent magnet is composed of a fastening nut 15, a permanent magnet steel 16, and a guide column 17, which are molded in a mounting shell 18 by high temperature resin injection molding. Figure 5 shown.

[0050] The action permanent magnet is formed by a connecting rod 19 and a permanent magnetic steel 20 and is molded in a plastic body 20 by high temperature resin injection molding. Figure 6 shown.

[0051] The shell has a cavity chamber, the top of the cavity chamber is a closed end, the bottom of the cavity chamber is an open end, and the open end is provided with two parts of threads, the internal thread is used for installing a fastening nut to play a fastening role, and the external thread is used for connecting a gland or an NPT connector for various wiring methods.

[0052] The actuator is installed in the housing cavity. The upward position is limited by the housing cavity, and the downward position is limited by the tightening nut, ensuring that key parameters such as the sensing distance of the precisely adjusted actuator do not change.

[0053] The sealed base is made of a metal base, and the four lead pins are fixed on the metal base through the glass insulator sintering technology. It not only has high strength, but also realizes the insulation and sealing performance of the lead pins and the shell.

[0054] The sealed base is installed in the housing cavity, and the connection strength and sealing are ensured by laser welding. The contact reliability of the contact system is protected under harsh conditions such as moisture and salt spray by vacuum baking, filling with inert gas, and sealing the process holes of the base.

[0055] The induction permanent magnet is fixed in the fixed cover 23 by the permanent magnetic steel 22 through the sealing process. Figure 7 shown.

[0056] The contact system is composed of a contact system base and a moving spring assembly, and the moving spring assembly and the middle spring are welded and connected by soft copper wire 29, such as Fig. 9 The contact system base is formed by injecting a high temperature resin into a base 28 by an upper static spring piece 24 for assembling a static contact 25, a lower static spring piece 26 for assembling a static contact 25, and a middle spring piece 27. Figure 8 shown.

[0057] The sealing base is made of a sealing bottom plate 30, four lead pins 31, and four glass insulators 32 through a base sintering process. Fig.10 shown.

[0058] The permanent magnet mechanism is composed of an induction permanent magnet, a fixed permanent magnet, an action permanent magnet, a moving reed assembly, a gasket, and a fastening nut. Figure 4 As shown. Install the moving reed 12, gasket 13 and fastening nut 14 of the moving contact 11 into the reed interface of the action permanent magnet in sequence, and tighten the fastening nut with a tool; then install the permanent magnet with the reed assembly into the mounting shell of the fixed permanent magnet, screw the induction permanent magnet into the connecting rod thread of the action permanent magnet, and debug the up and down movement flexibility of the permanent magnet mechanism and detect the key indicators of magnetic induction.

[0059] The actuator includes a permanent magnet mechanism 6 and a contact system 7. The contact system-base is installed in the mounting shell of the permanent magnet mechanism, and the moving spring assembly and the middle spring are welded and connected by soft copper wire 29. After the mechanical and electrical parameters of the contacts, the induction action distance and other requirements are debugged and tested, the fixing pins are installed.

[0060] The actuator 2 is installed in the proximity switch housing 1 and fixed with a fastening nut 3; after the key indicators are tested and qualified, the sealing base 4 is installed. The sealing base and the proximity switch housing are sealed by laser welding, and then vacuum baked. Inert gas is filled into the contact system cavity for protection, and the process hole of the sealing base is sealed to ensure that the inert gas in the contact system cavity does not leak. After the corresponding color of the cable lead wire 5 is welded to the corresponding lead pin, the proximity switch assembly is completed.

[0061] The proximity switch is connected to a gland and an NPT connector through a thread at the rear of a proximity switch housing, thereby forming a plurality of connection modes of a lead wire, a gland and a connector.

[0062] Install the moving reed 12, gasket 13 and fastening nut 14 of the assembled moving contact 11 into the reed interface of the actuating permanent magnet in sequence, and tighten the fastening nut with a tool; then install the permanent magnet with the installed reed assembly into the mounting shell of the fixed permanent magnet. After qualified debugging, screw the induction permanent magnet into the connecting rod thread of the actuating permanent magnet, debug the up and down movement flexibility of the permanent magnet mechanism and detect the key indicators of magnetic induction.

[0063] The permanent magnet mechanism designed by the present invention, which is composed of three groups of permanent magnets, namely, an induction permanent magnet, a fixed permanent magnet and an action permanent magnet, has long-term working stability in harsh environments.

[0064] The permanent magnets used in the permanent magnet mechanism are all made of hard magnetic alloys made of samarium-praseodymium-cobalt rare earth materials with a temperature resistance of 280°C. They have high magnetic energy levels and excellent characteristics under high temperature and long life test conditions. This solves the problem that foreign proximity switches use elastic materials such as springs, which fail due to factors such as changes in elastic stress under high temperature and long-term operation.

[0065] Permanent magnet mechanisms can provide greater force than other structural spring materials, providing the contact system with greater contact pressure and redundancy.

[0066] Due to the large magnetic holding force of the permanent magnet mechanism, the switching speed between the working state and the non-working state is faster than that of the mechanical structure with spring force.

[0067] When the proximity switch is not in operation, the normally closed contact is closed. The downward magnetic holding force is generated by the suction force generated by the induction permanent magnet and the fixed permanent magnet in the permanent magnet mechanism + the downward magnetic holding force generated by the action permanent magnet and the fixed permanent magnet in the permanent magnet mechanism. The above two magnetic holding forces provide a stable and reliable contact pressure redundancy for the closing state of the moving contact and the static contact in the normally closed contact of the contact system, improving the contact reliability of the proximity switch mechanism under harsh conditions.

[0068] When the external magnetic object reaches the inductive action distance of the switch, as the inductive distance decreases, the inductive permanent magnet and the external magnetic object produce a greater upward attraction. The characteristics of permanent magnet steel: the smaller the inductive distance, the greater the attraction. Overcoming the downward holding force of the permanent magnet mechanism, the inductive permanent magnet drives the moving reed assembly on the action permanent magnet to disconnect from the normally closed contact and close with the normally open contact, completing the circuit switching and entering the working state. At this time, the upward attraction produced by the inductive permanent magnet and the external magnetic object ensures the contact reliability of the contact system under harsh environmental conditions.

[0069] When the external magnetic object exceeds the induction action distance of the switch, the attraction between the induction permanent magnet and the external magnetic object decreases rapidly as the induction distance increases. When the downward holding force of the permanent magnet mechanism is greater than the upward attraction produced by the induction permanent magnet and the external magnetic object, the downward holding force of the permanent magnet mechanism drives the moving reed assembly on the action permanent magnet to disconnect from the normally open contact and close with the normally closed contact, returning to the non-working state.

[0070] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and one or more of the above embodiments are combined into one embodiment. Those skilled in the art can make various changes or modifications or combinations within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other at will.

Claims

1. A sealed passive proximity switch structure with a permanent magnet mechanism, characterized in that: include: A housing, an actuator, a first fastening nut, a sealing base and a cable lead, wherein the upper end of the actuator is connected to the bottom of the housing, the lower end of the actuator is matched with the fastening nut, the bottom of the fastening nut is matched with the sealing base, and the cable lead is arranged at the bottom of the sealing base; The actuator includes a permanent magnet mechanism and a contact system. The permanent magnet mechanism is arranged on the top of the contact system. The permanent magnet mechanism includes: An induction permanent magnet, a fixed permanent magnet, an action permanent magnet, a moving contact, a gasket and a second fastening nut, wherein the induction permanent magnet, the fixed permanent magnet and the action permanent magnet are sequentially connected from top to bottom, a moving contact is provided at the bottom of the action permanent magnet, the moving reed is provided on one side of the moving contact, the gasket is provided at the bottom of the moving reed, and is connected to the moving contact through the second fastening nut, The contact system comprises a contact system base and a dynamic spring assembly, wherein the contact system base is an injection molded body base, and the dynamic spring assembly comprises an upper static spring, a middle spring and a lower static spring, wherein the upper static spring and the lower static spring are matched and connected, and the bottom of the upper static spring and the top of the lower static spring are respectively provided with assembly static contacts, and the bottoms of the upper static spring, the middle spring and the lower static spring are all fixedly arranged on the surface of the injection molded body base; When the proximity switch is in a non-operating state, the normally closed contact is closed. When the proximity switch is in an operating state, the movable reed assembly is disconnected from the normally closed contact and closed with the normally open contact.

2. A sealed passive proximity switch structure with a permanent magnet mechanism according to claim 1, characterized in that: The induction permanent magnet comprises a first permanent magnet steel, a fixing cover is disposed on the outer shell of the permanent magnet steel, and the fixing cover is cooperatively connected with the first permanent magnet steel.

3. A sealed passive proximity switch structure with a permanent magnet mechanism according to claim 1, characterized in that: The fixed permanent magnet includes a mounting cover and a second permanent magnet, wherein the mounting cover is sleeved on the outside of the second permanent magnet, the top of the second permanent magnet is cooperatively connected with a third fastening nut, and the bottom of the second permanent magnet is sleeved with a guide column.

4. A sealed passive proximity switch structure with a permanent magnet mechanism according to claim 1, characterized in that: The action permanent magnet comprises a connecting rod and a third permanent magnet steel, the bottom of the connecting rod is cooperatively connected with the top of the third permanent magnet steel, and the bottom of the third permanent magnet steel is cooperatively connected with the plastic-encapsulated body.

5. A sealed passive proximity switch structure with a permanent magnet mechanism according to claim 1, characterized in that: The injection molding body base comprises a sealing bottom plate, a surface of the sealing bottom plate is provided with a plurality of lead pins, and the plurality of lead pins are respectively connected with glass insulators.

6. A sealed passive proximity switch structure with a permanent magnet mechanism according to claim 1, characterized in that: The shell has a cavity chamber, the top of the cavity chamber is a closed end, the bottom of the cavity chamber is an open end, and the open end is provided with internal threads and external threads. The internal threads are used to install fastening nuts for fastening, and the external threads are used to connect a gland or NPT connector.

7. A sealed passive proximity switch structure with a permanent magnet mechanism according to any one of claims 1 to 4, characterized in that: The first permanent magnet mechanism, the second permanent magnet mechanism and the third permanent magnet mechanism are made of samarium praseodymium cobalt rare earth materials.

8. A sealed passive proximity switch structure with a permanent magnet mechanism according to claim 1, characterized in that: The movable spring assembly adopts a semicircular flexible contact structure.

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