Sealed passive proximity switch with permanent magnet mechanism

Abstract

The present invention relates to the technical field of manufacturing of proximity switches for nuclear industry, and in particular to a sealed passive proximity switch with a permanent magnet mechanism. The sealed passive proximity switch comprises an actuating mechanism; the actuating mechanism comprises an induction permanent magnet, a fixed permanent magnet, an actuating permanent magnet and a normally closed contact; the induction permanent magnet, the fixed permanent magnet and the actuating permanent magnet are sequentially connected in the vertical direction; the induction permanent magnet, the fixed permanent magnet and the actuating permanent magnet are each provided with permanent magnet steel capable of generating magnetic force; and the normally closed contact comprises a movable contact and a stationary contact. Compared with the prior art, the present invention has the beneficial effects of not only having the characteristics of accurate induction action of external magnetic objects, high stability of contact units and high sealing protection grade, but also having long-term contact stability under a severe environment condition, achieving long-term reliable operation of the entire device.

Description

A sealed passive proximity switch with permanent magnet mechanism Technical Field

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

[0002] Nuclear power is one of the key construction projects of my country's "14th Five-Year Plan" and belongs to the category of clean energy. As the country pays more attention to environmental pollution, in the process of looking for alternative energy, people have begun 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. With the increasingly strong trend of localization, the existing proximity switches can no longer meet the needs of nuclear power sites.

[0003] In the existing technology, proximity switches are prone to occasional poor contact, contact surface oxidation, and unreliable contact conditions such as disconnection of normally closed contacts and inability to reliably connect normally open contacts due to their structural characteristics. These conditions cannot reflect the actual operating conditions of the monitored objects inside the actual nuclear power plant, and may lead to switch misjudgment.

[0004] At the same time, the contact unit 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 unit contacts from moisture, salt spray, and hydrogen sulfide atmosphere from contaminating them, causing unstable contact and leading to switch misjudgment.

[0005] Therefore, a new sealed passive proximity switch with a permanent magnet mechanism is needed to solve the above problems.

[0006] Summary of the Invention

[0007] The purpose of the present invention is to solve the deficiencies in the prior art and provide a proximity switch that can operate reliably for a long time at high temperatures, can provide a stable holding force for the contact unit, and can avoid poor contact of the contact unit caused by stress changes in the elastic material under harsh environmental conditions such as high temperature and strong vibration.

[0008] To achieve the above object, the present invention provides a sealed passive proximity switch structure with a permanent magnet mechanism, comprising:

[0009] 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;

[0010] 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:

[0011] An inductive permanent magnet, a fixed permanent magnet, an action permanent magnet, a moving contact, a gasket, and a second fastening nut 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.

[0012] The contact system includes a contact system base and a dynamic reed assembly, wherein the contact system base is an injection molded base, and the dynamic reed assembly includes an upper static reed, a middle reed, and a lower static reed. The upper static reed and the lower static reed are cooperatively connected, and the bottom of the upper static reed and the top of the lower static reed are respectively provided with assembly static contacts. The bottoms of the upper static reed, the middle reed, and the lower static reed are all fixedly arranged on the surface of the injection molded base.

[0013] When the proximity switch is in a non-working state, the normally closed contact is closed. When the proximity switch is in a working state, the movable reed assembly is disconnected from the normally closed contact and closed with the normally open contact.

[0014] Preferably, the induction permanent magnet comprises a first permanent magnet steel, the permanent magnet steel outer shell is provided with a fixed cover, and the fixed cover is cooperatively connected with the first permanent magnet steel.

[0015] 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 cooperated with the third fastening nut, and the bottom of the second permanent magnet is sleeved with a guide column.

[0016] Preferably, the action permanent magnet includes a connecting rod and a third permanent magnet, the bottom of the connecting rod is cooperatively connected to the top of the third permanent magnet, and the bottom of the third permanent magnet is cooperatively connected to the plastic-encapsulated body.

[0017] Preferably, the injection molded body base includes 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 to glass insulators.

[0018] Preferably, the housing 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 an internal thread and an external thread, the internal thread is used to install a fastening nut for fastening, and the external thread is used to connect a gland or an NPT connector.

[0019] Preferably, the first permanent magnet, the second permanent magnet and the third permanent magnet are made of samarium praseodymium cobalt rare earth material.

[0020] Preferably, the movable spring assembly adopts a semicircular flexible contact structure.

[0021] The present invention also provides a sealed passive proximity switch structure with a permanent magnet mechanism, comprising

[0022] An actuator, the actuator comprising an induction permanent magnet, a fixed permanent magnet, an action permanent magnet, and a normally closed contact, wherein the induction permanent magnet, the fixed permanent magnet, and the action permanent magnet are connected in sequence along a vertical direction, and each of the induction permanent magnet, the fixed permanent magnet, and the action permanent magnet is provided with a permanent magnet capable of generating magnetic force, and the normally closed contact comprises a moving contact and a static contact;

[0023] In the non-working state, the normally closed contact is closed, the induction permanent magnet and the permanent magnet in the fixed permanent magnet generate a downward magnetic holding force, the action permanent magnet and the permanent magnet in the fixed permanent magnet generate a downward magnetic holding force, and the resultant force of the two downward magnetic holding forces is greater than the upward contact reaction force generated by the normally closed contact, together forming a downward holding force to provide a stable contact pressure redundancy.

[0024] Preferably: an upward attractive force is generated between the external magnetic body and the induction permanent magnet, and the magnitude of the attractive force is negatively correlated with the distance between the external magnetic body and the induction permanent magnet. When the external magnetic body gradually approaches the induction permanent magnet until the upper limit of the induction action distance is reached, as the distance decreases, the upward attractive force generated by the induction permanent magnet and the external magnetic body increases, and is greater than the combined force of the downward magnetic force generated by the induction permanent magnet and the permanent magnets in the fixed permanent magnet and the downward magnetic force generated by the action permanent magnet and the permanent magnets in the fixed permanent magnet, that is, the attractive force is greater than the holding force, and the attractive force acts on the induction permanent magnet, driving the normally closed contact to disconnect and the normally open contact to close to complete the circuit switching, and at the same time, the induction permanent magnet and the external magnetic body form an upward holding force.

[0025] Preferably: when the external magnetic body gradually moves away from the induction permanent magnet and exceeds the induction action distance, the attraction between the induction permanent magnet and the external magnetic body decreases as the induction distance increases; when the downward holding force of the actuator is greater than the upward attraction generated by the induction permanent magnet and the external magnetic body, the downward holding force of the actuator drives the action permanent magnet and the normally closed contact to close and return to the non-working state.

[0026] Preferably: in the non-working state, the normally closed contact is closed, and the holding force generated by the induced permanent magnet and the fixed permanent magnet in the permanent magnet mechanism generates a downward magnetic holding force f2 + the downward magnetic holding force f1 generated by the moving permanent magnet and the fixed permanent magnet in the permanent magnet mechanism. The above two magnetic holding forces overcome the contact reaction force f3 of the moving contact and the static contact in the normally closed contact of the contact unit, forming a downward holding force f=f1+f2-f3, providing stable and reliable contact pressure redundancy, and improving the contact reliability of the proximity switch mechanism under harsh conditions.

[0027] Preferably, the upper end of the actuator is connected to the bottom of the housing, the lower end of the actuator is connected to the fastening nut, the bottom of the fastening nut is connected to the sealing base, and the cable lead is provided at the bottom of the sealing base;

[0028] Preferably: the actuator includes a permanent magnet mechanism and a contact unit, the permanent magnet mechanism is arranged at the top of the contact unit, the permanent magnet mechanism includes: an induction permanent magnet, a fixed permanent magnet, an action permanent magnet, a moving reed and a gasket, a moving reed is provided at the bottom of the action permanent magnet, the moving reed is arranged on one side of the moving contact, the gasket is arranged at the bottom of the moving reed, and is connected to the action permanent magnet through the fastening nut.

[0029] Preferably: the contact unit includes a contact unit base and a dynamic spring assembly, the contact unit base is an injection molded base, the contact unit base includes an upper static spring, a middle spring and a lower static spring, the upper static spring and the lower static spring are cooperatively connected, the bottom of the upper static spring and the top of the lower static spring are respectively provided with assembly static contacts, the upper static spring, the middle spring, the middle spring and the bottom of the lower static spring are all fixedly arranged on the surface of the injection molded base.

[0030] Preferably, the induction permanent magnet comprises a first permanent magnet steel, the first permanent magnet steel is provided with a fixed cover on its outer shell, and the fixed cover is cooperatively connected with the first permanent magnet steel;

[0031] 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 engaged with a third fastening nut, and the bottom of the second permanent magnet is sleeved with a guide column;

[0032] The action permanent magnet includes a connecting rod and a third permanent magnet. The bottom of the connecting rod is cooperatively connected to the top of the third permanent magnet, and the bottom of the third permanent magnet is cooperatively connected to the plastic-encapsulated body.

[0033] Preferably, the injection molded body base includes 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 to glass insulators.

[0034] Preferably, the housing 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 an internal thread and an external thread, the internal thread is used to install a fastening nut for fastening, and the external thread is used to connect a gland or an NPT connector.

[0035] Preferably, the movable spring assembly adopts a semicircular flexible contact structure.

[0036] The present invention also provides a sealed passive proximity switch, which is characterized in that it includes a permanent magnet mechanism consisting of an induction permanent magnet, a fixed permanent magnet and an action permanent magnet. In the non-working state, the normally closed contact is closed, and the holding force generated by the induction permanent magnet and the fixed permanent magnet in the permanent magnet mechanism generates a downward magnetic holding force f2 + the downward magnetic holding force f1 generated by the action permanent magnet and the fixed permanent magnet in the permanent magnet mechanism. The combined force of the above two magnetic holding forces overcomes the contact reaction force f3 of the moving contact and the static contact in the normally closed contact of the contact unit, forming a downward holding force f=f1+f2-f3, providing stable and reliable contact pressure redundancy, and improving the contact reliability of the proximity switch mechanism under harsh conditions.

[0037] Compared with the existing technology, the technical solution proposed in this application has the following beneficial effects:

[0038] 1. The assembly difficulty of the proximity switch is reduced, the adjustment and detection are simple and accurate, and the key indicators such as sensing action distance, contact pressure, and action sensitivity are more accurately controlled;

[0039] 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, improving the stability and reliability of the key technical indicators of the proximity switch.

[0040] 3. Design a permanent magnet mechanism consisting of three groups of permanent magnets: 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, provide a stable holding force for the contact unit, and avoid poor contact of the contact unit due to stress changes in the elastic material under harsh environmental conditions such as high temperature and strong vibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0042] FIG1 is an overall structural diagram of a proximity switch according to the present invention;

[0043] FIG2 is another connection diagram of the proximity switch of the present invention;

[0044] FIG3 is a structural diagram of the actuator of the present invention;

[0045] FIG4 is a structural diagram of a permanent magnet mechanism of the present invention;

[0046] FIG5 is a structural diagram of a fixed permanent magnet according to the present invention;

[0047] FIG6 is a structural diagram of an action permanent magnet of the present invention;

[0048] FIG7 is a structural diagram of an induction permanent magnet of the present invention;

[0049] FIG8 is a structural diagram of a contact unit according to the present invention;

[0050] FIG9 is a diagram showing the overall structure of the contact unit junction of the present invention;

[0051] FIG10 is a structural diagram of a contact unit junction base of the present invention;

[0052] FIG11 is a side view of the present invention;

[0053] FIG12 is a diagram of a proximity switch in a non-operating state according to the present invention;

[0054] FIG13 is a diagram showing the working state of the proximity switch of the present invention.

[0055] In the figure: 1. Housing, 2. Actuator, 3. First fastening nut, 4. Sealing base, 5. Cable lead, 6. Permanent magnet mechanism, 7. Contact unit, 8. Inductive 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-coated body, 22. First permanent magnet mechanism, 23. Fixed cover, 24. Upper static spring, 25. Static contact, 26. Lower static spring, 27. Middle spring, 28. Injection molding base, 29. Soft copper wire, 30. Sealing bottom plate, 31. Lead pin, 32. Glass insulator, 33. Gland, 34. Fixed pin, 35. Detection window, 36. External magnetic body. DETAILED DESCRIPTION

[0056] The following will clearly and completely describe and discuss the technical solutions in the embodiments of the present invention in conjunction with the 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.

[0057] 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 central component. 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 central component. 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 central component. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0058] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0059] Example 1

[0060] 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, as shown in FIG1 .

[0061] The actuator includes a permanent magnet mechanism 6 and a contact system 7, as shown in FIG3 . Key technical indicators of the proximity switch, such as contact stability, action flexibility, and sensing distance, can all be accurately achieved on the actuator.

[0062] An adjustment and detection window is 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.

[0063] The contact system-base is composed of an upper static spring 24, which holds a static contact 25; a lower static spring 26, which holds a static contact 25; and a middle spring 27, which are molded into a base 28 using high-temperature resin injection molding. The contact system-base is then assembled into a permanent magnet mechanism, and the moving spring assembly and the middle spring are welded together using soft copper wire 29. Once the commissioning and testing processes pass, the fixing pins are installed.

[0064] Install the actuator into a special debugging fixture, adjust and detect the contact pressure and contact surface in the actuator housing, and 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.

[0065] To solve the key indicators of foreign proximity switches such as sensing action distance, contact pressure, and action sensitivity, the switch must be assembled in a closed cavity, which is complex to assemble and difficult to detect.

[0066] 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 assembled with a moving contact 11, a gasket 13, and a fastening nut 14, as shown in FIG4 .

[0067] The fixed permanent magnet is composed of a fastening nut 15 , a permanent magnet 16 , and a guide column 17 , which are injection-molded in a mounting shell 18 through high-temperature resin, as shown in FIG5 .

[0068] The actuating permanent magnet is formed by a connecting rod 19 and a permanent magnet steel 20 and is injection-molded in a plastic body 20 through high-temperature resin, as shown in FIG6 .

[0069] The housing 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 to install a fastening nut for fastening, and the external thread is used to connect a gland or an NPT connector for various wiring methods.

[0070] The actuator is installed in the shell cavity. The upward position is limited by the shell cavity, and the downward position is limited by the fastening nut, ensuring that key parameters such as the sensing distance of the precisely adjusted actuator do not change.

[0071] The sealed base is made of a metal base, and the four lead pins are fixed to the metal base through glass insulator sintering technology. It not only has high strength, but also achieves insulation and sealing performance between the lead pins and the shell.

[0072] The sealed base is installed in the shell cavity, and the connection strength and sealing are guaranteed 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 base process holes.

[0073] The induction permanent magnet is fixed in the fixed cover 23 by the permanent magnetic steel 22 through a sealing process, as shown in FIG7 .

[0074] The contact system consists of a contact system base and a movable spring assembly, with the movable spring assembly and the middle spring welded together using soft copper wire 29, as shown in Figure 9. The contact system base is composed of an upper static spring 24 for mounting a static contact 25, a lower static spring 26 for mounting a static contact 25, and a middle spring 27, which are molded into a base 28 using high-temperature resin injection molding, as shown in Figure 8.

[0075] 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, as shown in FIG10 .

[0076] The permanent magnet mechanism consists of an induction permanent magnet, a fixed permanent magnet, an operating permanent magnet, a dynamic reed assembly, a gasket, and a fastening nut, as shown in Figure 4. The dynamic reed 12, gasket 13, and fastening nut 14, which are assembled with the moving contact 11, are sequentially installed into the reed interface of the operating permanent magnet, and the fastening nut is tightened using a tool. The permanent magnet with the reed assembly is then installed into the mounting housing of the fixed permanent magnet, and the induction permanent magnet is screwed into the connecting rod thread of the operating permanent magnet. The vertical movement flexibility of the permanent magnet mechanism is then debugged, and key magnetic induction indicators are tested.

[0077] The actuator comprises a permanent magnet mechanism 6 and a contact system 7. The contact system base is installed within the permanent magnet mechanism's mounting housing. The movable spring assembly and the center spring are welded together using soft copper wire 29. After the contact mechanical and electrical parameters, sensing distance, and other requirements are verified and tested, the fixing pins are installed.

[0078] The actuator 2 is installed in the proximity switch housing 1 and secured with a fastening nut 3. After key performance indicators are tested and found to pass, the sealing base 4 is installed. The sealing base and proximity switch housing are sealed by laser welding and then vacuum baked. The contact system cavity is filled with inert gas for protection, and the process holes in the sealing base are sealed to prevent leakage of the inert gas in the contact system cavity. The proximity switch assembly is completed by welding the corresponding color of the cable lead wires 5 to the corresponding lead pins.

[0079] The proximity switch is connected to the gland and the NPT connector through the thread at the rear of the proximity switch housing, forming multiple connection modes of lead wire, gland and connector.

[0080] 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.

[0081] The permanent magnet mechanism designed by the present invention, which consists of three groups of permanent magnets including an induction permanent magnet, a fixed permanent magnet and an action permanent magnet, has long-term working stability in harsh environments.

[0082] The permanent magnets used in the permanent magnet mechanism are all made of a hard magnetic alloy of samarium, praseodymium, and cobalt rare earth materials with a temperature resistance of 280°C. They have a high magnetic energy level and exhibit excellent properties under high-temperature, long-life test conditions. This solves the problem of failure caused by elastic materials such as springs in foreign proximity switches due to changes in elastic stress under high-temperature and long-term operation.

[0083] Compared with other structural spring materials, permanent magnet mechanisms can provide greater force, providing the contact system with greater contact pressure and redundancy.

[0084] 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 spring-loaded structure.

[0085] When the proximity switch is not in operation, the normally closed contacts are closed. The downward magnetic holding force generated by the attracting force between the induction permanent magnet and the fixed permanent magnet in the permanent magnet mechanism is combined with the downward magnetic holding force generated by the actuating permanent magnet and the fixed permanent magnet in the permanent magnet mechanism. The combined force provides stable and reliable contact pressure redundancy for the moving and stationary contacts in the normally closed contact system, improving the contact reliability of the proximity switch mechanism under harsh conditions.

[0086] When an external magnetic object reaches the switch's sensing distance, the inductive permanent magnet and the external magnetic object generate a greater upward attraction as the sensing distance decreases. The characteristic of permanent magnets is that the attraction increases as the sensing distance decreases. This overcomes the downward holding force of the permanent magnet mechanism, causing the inductive permanent magnet to disconnect the moving reed assembly on the actuating permanent magnet from the normally closed contact and close it with the normally open contact, completing the circuit switching and entering the operating state. At this point, the upward attraction generated by the inductive permanent magnet and the external magnetic object ensures the contact system's reliability even in harsh environmental conditions.

[0087] 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 moving permanent magnet to disconnect from the normally open contact and close with the normally closed contact, returning to the non-working state.

[0088] Example 2

[0089] Referring to Figures 1 to 3, the present invention further discloses a sealed passive proximity switch structure with a permanent magnet mechanism, comprising an actuator 2, the actuator comprising an inductive permanent magnet, a fixed permanent magnet, an actuating permanent magnet, and a normally closed contact, wherein the inductive permanent magnet, the fixed permanent magnet, and the actuating permanent magnet are connected in sequence along a vertical direction, and each of the inductive permanent magnet, the fixed permanent magnet, and the actuating permanent magnet is provided with a permanent magnet capable of generating magnetic force, and the normally closed contact comprises a moving contact and a static contact;

[0090] In the non-working state, the normally closed contacts are closed, the permanent magnets in the induction permanent magnet and the fixed permanent magnet generate a downward magnetic holding force, and the permanent magnets in the action permanent magnet and the fixed permanent magnet generate a downward magnetic holding force. The combined force of the two downward magnetic holding forces is greater than the upward contact reaction force generated by the normally closed contacts, and together form a downward holding force to provide a stable contact pressure redundancy.

[0091] An upward attractive force is generated between the external magnetic body and the induction permanent magnet, and the magnitude of the attractive force is negatively correlated with the distance between the external magnetic body and the induction permanent magnet. When the external magnetic body gradually approaches the induction permanent magnet until it reaches the upper limit of the induction action distance, as the distance decreases, the upward attractive force generated by the induction permanent magnet and the external magnetic body increases, and is greater than the combined force of the downward magnetic force generated by the induction permanent magnet and the permanent magnets in the fixed permanent magnet and the downward magnetic force generated by the action permanent magnet and the permanent magnets in the fixed permanent magnet, that is, the attractive force is greater than the holding force. The attractive force acts on the induction permanent magnet, driving the normally closed contact to open and the normally open contact to close to complete the circuit switching. At the same time, the induction permanent magnet and the external magnetic body form an upward holding force.

[0092] When the external magnetic body gradually moves away from the sensing permanent magnet and exceeds the sensing action distance, the attraction between the sensing permanent magnet and the external magnetic body decreases as the sensing distance increases. When the downward holding force of the actuator is greater than the upward attraction generated by the sensing permanent magnet and the external magnetic body, the downward holding force of the actuator drives the actuating permanent magnet and the normally closed contact to close, returning to the non-working state.

[0093] It also includes a proximity switch housing 1, a fastening nut 3, a sealing base 4, and a cable lead 5. The actuator includes a permanent magnet mechanism 6 and a contact unit 7. Key technical indicators of the proximity switch, such as contact stability, movement flexibility, and sensing distance, can all be accurately achieved on the actuator.

[0094] An adjustment and detection window is 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.

[0095] The contact unit-base is composed of an upper static spring 24, which holds the static contact 25; a lower static spring 26, which holds the static contact 25; and a middle spring 27, which are molded into a base 28 using high-temperature resin injection molding. The contact unit-base is then assembled into a permanent magnet mechanism, and the movable spring assembly and the middle spring are welded together using soft copper wire 29. Once the commissioning and testing processes pass, the fixing pin 34 is installed.

[0096] The actuator is installed in a dedicated debugging fixture, and the contact pressure and contact surface are precisely adjusted and tested in the actuator housing adjustment and detection window to ensure contact stability; the contact pressure is detected in the detection window using a dedicated dynamometer; and key indicators such as sensing action distance and action sensitivity are tested using a magnetic detection body in a dedicated magnetic testing fixture. In some embodiments, there are three types of contact contact: 1C is a transfer contact (moving contact and normally closed contact); 1A is a normally closed contact (moving contact and normally open contact); and 1D is a normally broken contact (moving contact and normally closed contact). The normally closed contact is also called a static contact. The transfer contact consists of a moving contact, a normally closed contact, and a normally open contact. The normally closed contact includes a moving contact and a lower static contact; the normally open contact includes a moving contact and an upper static contact.

[0097] Referring to Figures 4 to 6 , the permanent magnet mechanism comprises an induction permanent magnet 8, a fixed permanent magnet 9, an operating permanent magnet 10, a movable spring 12 for mounting a movable contact 11, a washer 13, and a fastening nut 14. The fixed permanent magnet comprises a fastening nut 15, a permanent magnet 16, and a guide post 17, which are injection-molded within a mounting housing 18 using high-temperature resin. The operating permanent magnet comprises a connecting rod 19 and a permanent magnet 20, which are injection-molded within an overmolded body 20 using high-temperature resin.

[0098] Specifically:

[0099] The housing 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 to install a fastening nut for fastening, and the external thread is used to connect a gland or an NPT connector for various wiring methods.

[0100] The actuator is installed in the shell cavity. The upward position is limited by the shell cavity, and the downward position is limited by the fastening nut, ensuring that key parameters such as the sensing distance of the precisely adjusted actuator do not change.

[0101] The sealed base is made of a metal base, and the four lead pins are fixed to the metal base through glass insulator sintering technology. It not only has high strength, but also achieves insulation and sealing performance between the lead pins and the shell.

[0102] The sealed base is installed in the shell cavity, and the connection strength and sealing are guaranteed by laser welding. The contact reliability of the contact unit is protected under harsh conditions such as moisture and salt spray by vacuum baking, filling with inert gas, and sealing the base process holes.

[0103] Referring to Figures 7 to 10 , the induction permanent magnet is formed by permanent magnet steel 22 secured within a fixed housing 23 through a sealing process. The contact unit comprises a contact unit base and a movable spring assembly, with the movable spring assembly and the center spring welded together using soft copper wire 29. The contact unit base is formed by high-temperature resin injection molding of an upper stationary spring 24, which houses the stationary contact 25; a lower stationary spring 26, which houses the stationary contact 25; and a center spring 27, into a base 28. The sealed base comprises a sealing base plate 30, four lead pins 31, and four glass insulators 32, manufactured through a base sintering process.

[0104] 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, 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.

[0105] The actuator comprises a permanent magnet mechanism 6 and a contact unit 7. The contact unit base is installed into the permanent magnet mechanism's mounting housing. The movable spring assembly and the center spring are welded together using soft copper wire 29. After the contact mechanical and electrical parameters, sensing distance, and other requirements are verified and tested, the fixing pins are installed.

[0106] The actuator 2 is installed in the proximity switch housing 1 and secured with a fastening nut 3. After key performance indicators are tested and found to pass, the sealing base 4 is installed. The sealing base and proximity switch housing are laser welded and sealed, followed by vacuum baking. The contact unit cavity is filled with inert gas for protection, and the process holes in the sealing base are sealed to prevent leakage of the inert gas in the contact unit cavity. The proximity switch assembly is completed by welding the corresponding color of the cable lead wires 5 to the corresponding lead pins.

[0107] The proximity switch is connected to the gland and the NPT connector through the thread at the rear of the proximity switch housing, forming multiple connection modes of lead wire, gland and connector.

[0108] 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.

[0109] The permanent magnets used in the permanent magnet mechanism are all made of a hard magnetic alloy of samarium, praseodymium, and cobalt rare earth materials with a temperature resistance of 280°C. They have a high magnetic energy level and exhibit excellent properties under high-temperature, long-life test conditions. This solves the problem of failure caused by elastic materials such as springs in foreign proximity switches due to changes in elastic stress under high-temperature and long-term operation.

[0110] Permanent magnet mechanisms provide greater force than other spring-loaded structures, providing greater contact pressure and redundancy for the contact unit. Due to their greater magnetic holding force, permanent magnet mechanisms offer faster switching speeds between the operating and non-operating states compared to mechanical spring-loaded structures.

[0111] With the support of the above structure, as shown in Figures 12 and 13, the proximity switch provided by the present invention is in a non-operating state with its normally closed contacts closed. The holding force generated by the induction permanent magnet and the fixed permanent magnet in the permanent magnet mechanism generates a downward magnetic holding force f2, which is combined with the downward magnetic holding force f1 generated by the actuating permanent magnet and the fixed permanent magnet in the permanent magnet mechanism. These two combined magnetic holding forces overcome the contact reaction force f3 between the moving and stationary contacts in the normally closed contact system, forming a downward holding force f = f1 + f2 - f3. This provides stable and reliable contact pressure redundancy, improving the contact reliability of the proximity switch mechanism under harsh conditions.

[0112] When the external magnetic body reaches the upper limit of the induction action distance of the switch, as the induction distance L decreases, the upward magnetic attraction force F1 generated by the induction permanent magnet and the external magnetic body increases; as the induction action distance of the external magnetic body from the switch gradually decreases (greater than the lower limit of the induction action distance), the upward magnetic attraction force F1 generated by the induction permanent magnet (22) and the external magnetic body increases rapidly, overcoming the downward magnetic force F2 generated by the induction permanent magnet and the fixed permanent magnet in the permanent magnet mechanism and the downward magnetic force F3 generated by the action permanent magnet and the fixed permanent magnet in the permanent magnet mechanism, and disconnecting the moving reed assembly on the action permanent magnet from the normally closed contact and closing it with the normally open contact, completing the circuit switching. At the same time, the magnetic attraction force F1 generated by the induction permanent magnet and the external magnetic body overcomes the contact reaction force F4 of the moving contact, forming an upward holding force F=F1-F2-F3-F4, ensuring the contact reliability of the contact system under harsh environmental conditions. See Figure 13 - working state.

[0113] When the external magnetic body gradually moves away from the proximity switch and exceeds the induction action distance of the switch, the attraction F1 between the induction permanent magnet and the external magnetic body decreases rapidly as the induction distance increases. When the downward holding force f of the permanent magnet mechanism is greater than the upward attraction F produced by the induction permanent magnet and the external magnetic body, the downward holding force f of the permanent magnet mechanism drives the moving reed assembly on the moving permanent magnet to disconnect from the normally open contact and close with the normally closed contact, returning to the non-working state.

[0114] Example 3

[0115] This embodiment provides a sealed passive proximity switch, including a permanent magnet mechanism consisting of an induction permanent magnet, a fixed permanent magnet, and an actuating permanent magnet. In the non-operating state, the normally closed contact is closed, and the holding force generated by the induction permanent magnet and the fixed permanent magnet in the permanent magnet mechanism generates a downward magnetic holding force f2, and the downward magnetic holding force f1 generated by the actuating permanent magnet and the fixed permanent magnet in the permanent magnet mechanism. The combined force of these two magnetic holding forces overcomes the contact reaction force f3 between the moving contact and the stationary contact in the normally closed contact of the contact unit, forming a downward holding force f = f1 + f2 - f3, providing stable and reliable contact pressure redundancy and improving the contact reliability of the proximity switch mechanism under harsh conditions.

[0116] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and that one or more of the above embodiments may be combined. Those skilled in the art may make various changes, modifications, or combinations within the scope of the claims, which do 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 may be combined with each other in any manner.

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 2, 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 3, 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 claim 4, characterized in that: The first permanent magnetic steel, the second permanent magnetic steel and the third permanent magnetic steel are made of samarium praseodymium cobalt rare earth material.

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.

9. A sealed passive proximity switch structure with a permanent magnet mechanism, characterized in that: include An actuator, the actuator comprising an induction permanent magnet, a fixed permanent magnet, an action permanent magnet and a normally closed contact, the induction permanent magnet, the fixed permanent magnet and the action permanent magnet are connected in sequence along a vertical direction, the induction permanent magnet, the fixed permanent magnet and the action permanent magnet are each provided with a permanent magnet capable of generating magnetic force, and the normally closed contact comprises a moving contact and a static contact; In the non-working state, the normally closed contact is closed, the induction permanent magnet and the permanent magnet in the fixed permanent magnet generate a downward magnetic holding force, the action permanent magnet and the permanent magnet in the fixed permanent magnet generate a downward magnetic holding force, and the combined force of the two downward magnetic holding forces is greater than the upward contact reaction force generated by the normally closed contact, and together form a downward holding force to provide a stable contact pressure redundancy.

10. A sealed passive proximity switch structure with a permanent magnet mechanism according to claim 9, characterized in that: An upward attractive force is generated between the external magnetic body and the induction permanent magnet, and the magnitude of the attractive force is negatively correlated with the distance between the external magnetic body and the induction permanent magnet. When the external magnetic body gradually approaches the induction permanent magnet until the upper limit of the induction action distance is reached, as the distance decreases, the upward attractive force generated by the induction permanent magnet and the external magnetic body increases, and is greater than the combined force of the downward magnetic force generated by the induction permanent magnet and the permanent magnet steel in the fixed permanent magnet and the downward magnetic force generated by the action permanent magnet and the permanent magnet steel in the fixed permanent magnet, that is, the attractive force is greater than the holding force, and the attractive force acts on the induction permanent magnet to drive the normally closed contact to open and close with the normally open contact to complete the circuit switching, and at the same time, the induction permanent magnet and the external magnetic body form an upward holding force.

11. A sealed passive proximity switch structure with a permanent magnet mechanism according to claim 10, characterized in that: When the external magnetic body gradually moves away from the induction permanent magnet and exceeds the induction action distance, the attraction between the induction permanent magnet and the external magnetic body decreases as the induction distance increases. When the downward holding force of the actuator is greater than the upward attraction generated by the induction permanent magnet and the external magnetic body, the downward holding force of the actuator drives the action permanent magnet and the normally closed contact to close and return to the non-working state.

12. A sealed passive proximity switch structure with a permanent magnet mechanism according to claim 11, characterized in that: In the non-working state, the normally closed contacts are closed, and the holding force generated by the induction permanent magnet and the fixed permanent magnet in the permanent magnet mechanism generates a downward magnetic holding force f2 + the downward magnetic holding force f1 generated by the action permanent magnet and the fixed permanent magnet in the permanent magnet mechanism. The above two magnetic holding forces overcome the contact reaction force f3 of the moving contact and the static contact in the normally closed contact of the contact unit, forming a downward holding force f=f1+f2-f3, providing a stable and reliable contact pressure redundancy, and improving the contact reliability of the proximity switch mechanism under harsh conditions.

13. [Corrected 10.09.2024 according to Rule 91] A sealed passive proximity switch structure with a permanent magnetic mechanism according to claim 12, characterized in that: The upper end of the actuator is connected to the bottom of the shell, the lower end of the actuator is connected with the fastening nut, the bottom of the fastening nut is connected with the sealing base, and the cable lead is arranged at the bottom of the sealing base.

14. A sealed passive proximity switch structure with a permanent magnet mechanism according to claim 13, characterized in that: The actuator includes a permanent magnet mechanism and a contact unit, wherein the permanent magnet mechanism is arranged at the top of the contact unit, and the permanent magnet mechanism includes: an induction permanent magnet, a fixed permanent magnet, an action permanent magnet, a moving reed and a gasket. A moving reed is provided at the bottom of the action permanent magnet, and the moving reed is arranged on one side of the moving contact. The gasket is arranged at the bottom of the moving reed and is connected to the action permanent magnet through the fastening nut.

15. A sealed passive proximity switch structure with a permanent magnet mechanism according to claim 14, characterized in that: The contact unit includes a contact unit base and a moving spring assembly, wherein the contact unit base is an injection molded body base, and the contact unit base includes an upper static spring, a middle spring and a lower static spring, wherein the upper static spring and the lower static spring are cooperatively connected, and assembly static contacts are respectively provided at the bottom of the upper static spring and the top of the lower static spring, and the upper static spring, the middle spring, the middle spring and the bottom of the lower static spring are all fixedly arranged on the surface of the injection molded body base.

16. A sealed passive proximity switch structure with a permanent magnet mechanism according to claim 12, characterized in that: The induction permanent magnet comprises a first permanent magnetic steel, a fixed cover is disposed on the outer cover of the first permanent magnetic steel, and the fixed cover is cooperatively connected with the first permanent magnetic steel; The fixed permanent magnet comprises 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 matched and connected with a third fastening nut, and the bottom of the second permanent magnet is sleeved with a guide column; 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.

17. A sealed passive proximity switch structure with a permanent magnet mechanism according to claim 15, 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.

18. A sealed passive proximity switch structure with a permanent magnet mechanism according to claim 13, 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.

19. A sealed passive proximity switch structure with a permanent magnet mechanism according to claim 15, characterized in that: The movable spring assembly adopts a semicircular flexible contact structure.

20. A sealed passive proximity switch, characterized in that: The invention comprises a permanent magnet mechanism composed of an induction permanent magnet, a fixed permanent magnet and an action permanent magnet. In a non-working state, the normally closed contact is closed, and a downward magnetic holding force f2 is generated under the action of the holding force generated by the induction permanent magnet and the fixed permanent magnet in the permanent magnet mechanism, and a downward magnetic holding force f1 is generated by the action permanent magnet and the fixed permanent magnet in the permanent magnet mechanism. The above two magnetic holding forces overcome the contact reaction force f3 of the moving contact and the static contact in the normally closed contact of the contact unit, and form a downward holding force f=f1+f2-f3, so as to provide a stable and reliable contact pressure redundancy and improve the contact reliability of the proximity switch mechanism under harsh conditions.

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