Proximity switch and valve warning system

Abstract

This invention relates to the field of nuclear power equipment, and more particularly to a proximity switch and valve warning system. The proximity switch includes: an outer cylinder; a conductive component disposed within the outer cylinder and near its open end; a drive assembly including a first magnetic element, a second magnetic element, a cam, and a rotating shaft, the rotating shaft being rotatably mounted within the outer cylinder, and the axis of the rotating shaft being perpendicular to the central axis of the outer cylinder; the cam being fitted onto the rotating shaft, with two actuating parts spaced apart on its side; a receiving groove provided in the wall of the cam's shaft hole, the first magnetic element being installed in the receiving groove and capable of driving the cam to rotate; the second magnetic element being fixed within the outer cylinder and located between the first magnetic element and the conductive component; and a contact assembly disposed within the outer cylinder and located between the cam and the second magnetic element, the contact assembly including two microswitches. The valve warning system includes a valve, a bracket, electrical connections, an alarm, and the proximity switch as described above. This invention effectively prevents the proximity switch from breaking circuit when subjected to vibration.

Description

Technical Field

[0001] This invention relates to the field of nuclear power equipment, and more particularly to proximity switches and valve warning systems. Background Technology

[0002] A proximity switch is a position switch that can be operated without direct mechanical contact with moving parts. When the distance between an object and the sensing surface of the switch is less than a certain value, the proximity switch will still activate even if the object and the switch are not in direct contact, thereby providing a switching signal to control certain components.

[0003] Existing proximity switches include an outer cylinder, a movable magnetic component, a fixed magnetic component, a connecting plate, and a connecting shaft. One end of the connecting shaft is fixedly connected to the movable magnetic component, and the other end passes through the fixed magnetic component fastened to the outer cylinder and is fixedly connected to the connecting plate. The connecting plate has a contact point along the axis of the outer cylinder. Influenced by a target object outside the proximity switch and the fixed magnetic component, the movable magnetic component reciprocates inside the outer cylinder along its axis, thereby causing the connecting plate to reciprocate synchronously. This allows the connecting plate to contact one of the two contacts at different times.

[0004] However, when the proximity switch is subjected to vibration, the connecting plate may separate from the contacts, causing an open circuit in the proximity switch control circuit. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a proximity switch and valve warning system that effectively prevents the proximity switch from breaking down when subjected to vibration.

[0006] This invention provides a proximity switch, comprising:

[0007] The outer cylinder includes an open end and a closed end;

[0008] A conductive component, disposed inside the outer cylinder and near the opening end of the outer cylinder, is used to connect electrical connectors;

[0009] The drive assembly includes a first magnetic element, a second magnetic element, a cam, and a rotating shaft. The rotating shaft is rotatably mounted inside an outer cylinder, and the axis of the rotating shaft is perpendicular to the central axis of the outer cylinder. The cam is fitted onto the rotating shaft, and two actuating parts are spaced apart on the side of the cam. The shaft hole of the cam has a receiving groove in its wall, and the first magnetic element is installed in the receiving groove and can drive the cam to rotate. The second magnetic element is fixed inside the outer cylinder and located between the first magnetic element and the conductive component.

[0010] A contact assembly is disposed inside the outer cylinder and located between the cam and the second magnetic element, the contact assembly comprising two microswitches;

[0011] When the cam rotates to a first angle, one of the actuating parts of the cam can trigger one of the micro-touch switches; when the cam rotates to a second angle, the other actuating part of the cam can trigger another micro-touch switch.

[0012] In one alternative implementation, the receiving groove is an annular groove surrounding the rotating shaft, and the first magnetic element is a magnetic ring made of magnetic core material.

[0013] In one alternative implementation, the magnetic ring is a closed or semi-closed shape.

[0014] In one alternative implementation, the shaft hole has a large-diameter end and a small-diameter end, and the large-diameter end of the shaft hole is provided with a washer, the washer and the hole wall of the shaft hole defining a receiving groove for accommodating the first magnetic component.

[0015] In one alternative implementation, the two microswitches are arranged axially spaced along the cam.

[0016] In one alternative implementation, a mounting base is further included, which is disposed inside the outer cylinder and fixed to the outer cylinder. Both ends of the rotating shaft pass through the mounting base, and the mounting base is provided with mounting holes coaxial with the outer cylinder. The second magnetic component is fixed in the mounting holes.

[0017] In one alternative implementation, the conductive component includes three terminals and a base, with the three terminals passing through the base and one end of the three terminals facing the second magnetic element electrically connected to the two micro-touch switches.

[0018] In one alternative implementation, a clamping nut is further included, which is disposed inside the outer cylinder and threadedly connected to the outer cylinder, and the clamping nut is located between the conductive component and the open end of the outer cylinder.

[0019] In one alternative implementation, three elastic sleeves are further included, each sleeved onto the end of one of the three terminals facing the opening of the outer cylinder.

[0020] According to another aspect of the present invention, a valve warning system is provided, including a valve, a bracket, an electrical connector, an alarm, and a proximity switch as described above;

[0021] The valve stem is provided with a third magnetic element, the valve and the proximity switch are mounted on the bracket, and the alarm is electrically connected to the terminal block of the proximity switch base through the electrical connector.

[0022] Compared with the prior art, the proximity switch of the present invention includes an outer cylinder, a conductive component, a driving component, and a contact component. The outer cylinder includes an open end and a closed end. The conductive component is disposed inside the outer cylinder and near the open end of the outer cylinder, and is used to connect an electrical connector. The driving component includes a first magnetic component, a second magnetic component, a cam, and a rotating shaft. The rotating shaft is rotatably mounted inside the outer cylinder, and the axis of the rotating shaft is perpendicular to the central axis of the outer cylinder. The cam is fitted onto the rotating shaft, and two actuating parts are arranged at intervals on the side of the cam. The wall of the cam's shaft hole is provided with a receiving groove, and the first magnetic component is installed in the receiving groove and can drive the cam to rotate. The second magnetic component is fixed inside the outer cylinder and located between the first magnetic component and the conductive component. When the cam rotates to a first angle, one of the actuating parts of the cam can trigger one of the micro-switches; when the cam rotates to a second angle, the other actuating part of the cam can trigger the other micro-switches. In this way, when the proximity switch is subjected to external vibration, on the one hand, due to the interaction between the first magnetic component and the second magnetic component, the cam is difficult to rotate; on the other hand, even if the cam rotates slightly, the actuating part of the cam still compresses the micro-touch switch, and the compressed micro-touch switch is still in working state, so it will not cause the circuit controlled by the proximity switch to be broken. Attached Figure Description

[0023] Figure 1 A schematic diagram showing the structure of a proximity switch;

[0024] Figure 2 A schematic diagram showing the structure of the outer cylinder;

[0025] Figure 3 A schematic diagram showing the exploded structure of the driving component;

[0026] Figure 4 This diagram shows the structure of the driving component and the micro-touch switch.

[0027] Figure 5 A schematic diagram showing the structure of a conductive component;

[0028] In the picture,

[0029] 1-Outer cylinder; 2-Conductive component; 21-Terminal; 211-First terminal; 212-Second terminal; 213-Third terminal; 22-Base; 23-Elastic sleeve; 3-Drive component; 31-First magnetic component; 32-Second magnetic component; 33-Cam; 331-Actuating part; 332-Large diameter end; 333-Small diameter end; 34-Shaft; 35-Washer; 36-First bushing; 37-Second bushing; 4-Micro switch; 5-Mounting base; 51-First mounting base; 52-Second mounting base; 6-Pressure nut. Detailed Implementation

[0030] To further understand the present invention, embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the present invention.

[0031] Existing proximity switches include an outer cylinder, a movable magnetic component, a fixed magnetic component, a connecting plate, and a connecting shaft. One end of the connecting shaft is fixedly connected to the movable magnetic component, and the other end passes through the fixed magnetic component fastened to the outer cylinder and is fixedly connected to the connecting plate. The connecting plate has a contact point along the axis of the outer cylinder. The movable magnetic component, influenced by a target object outside the proximity switch and the fixed magnetic component, can reciprocate inside the outer cylinder along its axis, thereby causing the connecting plate to reciprocate synchronously, resulting in the connecting plate contacting one of the two contacts at different times. However, when the proximity switch is subjected to external vibration, the connecting plate and the contacts are prone to separation, causing an open circuit in the proximity switch control circuit.

[0032] After repeated consideration and verification, the inventors discovered that by configuring the drive component of the proximity switch to include a cam, fixing a movable magnetic component to the cam and enabling the cam to rotate around its axis, and placing a fixed magnetic component on one side of the cam, the movable magnetic component can drive the cam to rotate under the action of the fixed magnetic component and an external target component. The contact component is configured as a microswitch; when the cam rotates to a certain angle, the protruding part of the cam's sidewall can trigger the microswitch. Thus, when the proximity switch is subjected to external vibration, on the one hand, the cam is difficult to rotate under the action of magnetic force; on the other hand, even if the cam rotates slightly, the protruding part of the cam still compresses the microswitch, keeping the microswitch in a working state and preventing the proximity switch control circuit from being broken.

[0033] In view of this, the inventors designed a proximity switch, which includes an outer cylinder, a conductive component, a driving component, and a contact component. The outer cylinder is open at one end and closed at the other. The conductive component is disposed inside the outer cylinder near the open end and is used to connect an electrical connector. The driving component includes a first magnetic component, a second magnetic component, a cam, and a rotating shaft. The rotating shaft is rotatably mounted inside the outer cylinder, and the axis of the rotating shaft is perpendicular to the central axis of the outer cylinder. The cam is fitted onto the rotating shaft, and two actuating parts are spaced apart on the side of the cam. The wall of the cam's shaft hole has a receiving groove, and the first magnetic component is installed in the receiving groove and can drive the cam to rotate. The second magnetic component is fixed inside the outer cylinder and located between the first magnetic component and the conductive component. The contact component is disposed inside the outer cylinder and located between the cam and the second magnetic component. The contact component includes two microswitches. When the cam rotates to a first angle, one of the actuating parts of the cam can trigger one of the microswitches; when the cam rotates to a second angle, the other actuating part of the cam can trigger the other microswitch. In this way, when the proximity switch is subjected to external vibration, the first magnetic component is difficult to rotate under the action of magnetic force, and the cam fixed to the first magnetic component is also difficult to rotate. Even if the cam rotates slightly, the protruding part of the cam still compresses the micro-touch switch, and the micro-touch switch remains in working state, so the circuit controlled by the proximity switch will not be broken.

[0034] To further understand the present invention, the proximity switch and valve warning system provided by the present invention will be described in detail below with reference to the embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0035] Example 1

[0036] Figure 1 This is a schematic diagram of the proximity switch provided in this embodiment, as shown below. Figure 1 As shown, the proximity switch provided in this embodiment includes an outer cylinder 1, a conductive component 2, a driving component 3, and a contact component. The outer cylinder 1 is configured to be open at one end and closed at the other. For example, the left end of the outer cylinder 1 is the closed end, and the right end is the open end. The conductive component 2, the driving component 3, and the contact component are disposed inside the outer cylinder 1. It is easy to understand that the outer cylinder 1 serves as the housing of the proximity switch, and the diameter and length of the outer cylinder 1 can be set by those skilled in the art according to actual needs.

[0037] Figure 2 This is a schematic diagram of the outer cylinder provided in this embodiment. Figure 2As shown, one possible implementation is that the outer wall of the left end of the outer cylinder 1 can be provided with external threads, so that the proximity switch can be fixed in the installation position through the external threads of the outer cylinder 1. The outer diameter of the left side portion of the outer cylinder 1 is smaller than the outer diameter of the middle portion of the outer cylinder 1, that is to say, when the proximity switch is installed by thread, the middle portion of the outer cylinder 1 can be used for limiting. For example, the outer wall of the middle portion of the outer cylinder 1 can be set as a hexagonal prism to facilitate the use of a screwdriver to screw the proximity switch. The size of the right side portion of the outer cylinder 1 can be determined by those skilled in the art based on the size of the electrical connector connected to the outer cylinder 1.

[0038] Preferably, a metal material can be used as the material for the outer cylinder 1. For example, the outer cylinder 1 can be made of stainless steel. By making the outer cylinder 1 metal, the structural strength of the outer cylinder 1 is ensured, and the metal material is not affected by radiation. Therefore, the proximity switch provided in this embodiment can be applied in harsh working environments, such as underwater or nuclear power plants.

[0039] like Figure 1 As shown, a drive assembly 3 is disposed inside the outer cylinder 1. The drive assembly 3 includes a first magnetic element 31, a second magnetic element 32, a cam 33, and a rotating shaft 34. The second magnetic element 32 is fixed to the position of the outer cylinder 1. One possible implementation is that a mounting base 5 is disposed inside the outer cylinder 1, located inside the outer cylinder 1 and fixed thereto. Exemplarily, the mounting base 5 includes a first mounting base 51 and a second mounting base 52. The left end of the first mounting base 51 abuts against the closed end of the outer cylinder 1, and the left end of the second mounting base 52 abuts against the right end of the first mounting base 51. The first mounting base 51 and the second mounting base 52 define a mounting hole for fixing the second magnetic element 32. The mounting hole is coaxial with the outer cylinder 1. The second magnetic element 32 is formed into a ring structure and is coaxially disposed with the outer cylinder 1, and is fixed within the mounting hole.

[0040] It is worth mentioning that the mounting base 5 should be made of a non-magnetic material to prevent the conduction of magnetism when the second magnetic component 32 is fixed using the mounting base 5. Preferably, the material of the mounting base 5 also has high temperature resistance and radiation resistance properties, thereby ensuring that the proximity switch provided in this embodiment can be used in harsh environments.

[0041] Figure 1 As shown, the rotating shaft 34 is rotatably mounted inside the outer cylinder 1, with its axis perpendicular to the axis of the outer cylinder 1. One possible implementation is that the rotating shaft 34 is positioned between the closed end of the outer cylinder 1 and the second magnetic element 32. Exemplarily, both ends of the rotating shaft 34 pass through the first mounting base 51. Specifically, through holes for fixing the rotating shaft 34 are provided on the upper and lower sides of the sidewall of the first mounting base 51. Preferably, a first bushing 36 is provided between both ends of the rotating shaft 34 and the through holes of the first mounting base 51 to prevent the rotating shaft 34 from wearing down the first mounting base 51.

[0042] Figure 3 This is an exploded structural diagram of the driving component provided in this embodiment. Figure 1 and Figure 3 As shown, the cam 33 is mounted on the rotating shaft 34, specifically, the cam 33 is located between the two first bushings 36. Two actuating parts 331 are spaced apart on the cam 33, specifically, the two actuating parts 331 are spaced apart along the axial direction of the outer cylinder 1. It should be noted that the actuating part 331 is the outwardly protruding portion of the sidewall of the cam 33, and its outer sidewall is a curved surface protruding outward from the cam 33. When the cam 33 rotates to a certain angle, the actuating part 331 can press the contact assembly, thereby putting the contact assembly into a working state. In this embodiment, the radial position of the actuating part 331 on the cam 33 is not limited. For example, one actuating part 331 can protrude to the left from the sidewall of the cam 33, and the other actuating part 331 can protrude to the right from the sidewall of the cam 33, that is, the included angle between the two actuating parts 331 is 180 degrees. Those skilled in the art can also set the included angle between the two actuating parts 331 to other angles, according to actual needs.

[0043] Continue to refer to Figure 3 The shaft hole of the cam 33 has a receiving groove on its wall. The receiving groove is used to fix the first magnetic component 31. In this embodiment, the fixing method between the first magnetic component 31 and the receiving groove is not limited. For example, the first magnetic component 31 and the receiving groove can be bonded together.

[0044] like Figure 1 and Figure 3 As shown, the first magnetic element 31 is a closed magnetic ring, or, those skilled in the art may also configure the magnetic ring as a semi-closed shape. Those skilled in the art will understand that one end of the magnetic ring's sidewall is the N pole of the magnetic ring, and the other end is the S pole of the magnetic ring. When no third magnetic element is nearby, the magnetic ring rotates in the opposite direction to the second magnetic element 32, facing towards the second magnetic element 32.

[0045] The following describes several possible implementations of the receiving slot, but those skilled in the art should understand that the specific implementations of the receiving slot described below should not be regarded as specific limitations on the receiving slot.

[0046] like Figure 3As shown, one possible implementation is that the shaft hole of the cam 33 has a large-diameter end 332 and a small-diameter end 333. The small-diameter end 333 of the shaft hole is used for fixed connection with the rotating shaft 34. A washer 35 is provided at the large-diameter end 332 of the shaft hole. It is easy to understand that the washer 35 is provided with a through hole for the rotating shaft 34 to pass through. The washer 35 and the hole wall of the shaft hole define a receiving groove for accommodating the first magnetic element 31. When the first magnetic element 31 is placed inside the receiving groove, the first magnetic element 31 abuts against the washer 35. At the same time, in order to prevent the rotating shaft 34 from wearing the first magnetic element 32, a second bushing 37 is provided between the rotating shaft 34 and the first magnetic element 32. Preferably, the two first bushings 36 abut against the washer 35 and the end of the cam 33 respectively, to prevent the cam 33 from deviating along the axial direction of the rotating shaft 34 during rotation.

[0047] Another possible implementation is that the receiving groove is an annular groove surrounding the rotating shaft 34, and correspondingly, the first magnetic element 31 is a magnetic ring made of magnetic core material. Those skilled in the art will understand that when the receiving groove is set as an annular groove surrounding the rotating shaft 34, and the first magnetic element 31 is fixed inside the annular groove, the first magnetic element 31 will not have direct contact with the rotating shaft 34, that is, the rotating shaft 34 will not cause wear to the first magnetic element 31.

[0048] like Figure 1 As shown, the contact assembly is disposed inside the outer cylinder 1 and located between the cam 33 and the second magnetic element 32. Exemplarily, the contact assembly includes two microswitches 4, which are positioned along the axial direction of the cam 33. Figure 1 The vertical spacing is set in the middle. It should be noted that when the button of the micro switch 4 is compressed to the preset position, the micro switch 4 starts to work. There is still a certain distance between the button of the micro switch 4 and the maximum compressible position. Therefore, when the proximity switch is subjected to external vibration and the cam 33 rotates slightly, the micro switch is still in the triggered state and the circuit controlled by the proximity switch will not be broken.

[0049] Figure 4 This is a schematic diagram of the drive assembly and micro-touch switch provided in this embodiment. Figure 4 The two micro-switches 4 are arranged in opposite directions. However, those skilled in the art can also arrange the two micro-switches 4 in the same direction; this embodiment is not limited to this. Figure 4As shown, exemplarily, when no third magnetic element is near the proximity switch, the magnetism of the first magnetic element 31 towards the second magnetic element 32 is opposite to that of the second magnetic element 32. At this time, the cam 33 rotates to a first angle, and the actuating part 331 located above triggers the micro-touch switch 4 located above. When the third magnetic element approaches the first magnetic element 31 until the magnetic force between the third magnetic element and the first magnetic element 31 is greater than the magnetic force between the first magnetic element 31 and the second magnetic element 32, the third magnetic element causes the first magnetic element 31 to rotate, which in turn drives the cam 33 to rotate. When the cam 33 rotates to a second angle, the actuating part 331 located below the cam 33 triggers the micro-touch switch 4 below. It is easy to understand that the magnetism of the third magnetic element towards the first magnetic element 31 is the same as the magnetism of the second magnetic element 32 towards the first magnetic element 31.

[0050] Figure 5 This is a schematic diagram of the conductive component provided in this embodiment. Figure 1 and Figure 5 As shown, the micro-touch switch 4 and the conductive component 2 can be electrically connected by a cable. One possible implementation is that the second mounting base 52 is provided with a through hole for the cable to pass through. The left end of the cable passes through the through hole of the second mounting base 52 and is connected to the micro-touch switch 4, while the right end of the cable is connected to the conductive component 2.

[0051] Continue to refer to Figure 1 and Figure 5 The conductive component 2 includes three terminals 21 and a base 22. The three terminals 21 pass through the base 22, and the ends of the three terminals 21 facing the second magnetic component 32 are electrically connected to the two micro-touch switches 4. The base 22 is located inside the outer cylinder 1 and abuts against the right end face of the second mounting base 52.

[0052] Specifically, the proximity switch can connect to two external circuits and switch between them. The first external circuit is electrically connected to the right ends of the first terminal 211 and the second terminal 212. The second external circuit is electrically connected to the right ends of the second terminal 212 and the third terminal 213, where the second terminal 212 is the common terminal for both the first and second external circuits. The left ends of the first terminal 211 and the second terminal 212 are electrically connected to the upper micro-switch 4, and the left ends of the second terminal 212 and the third terminal 213 are electrically connected to the lower micro-switch 4. The proximity switch provided in this embodiment switches between the first and second external circuits by controlling the upper and lower micro-switch 4 to trigger them respectively.

[0053] Those skilled in the art will understand that the proximity switch provided in this embodiment is equipped with a conductive component 2, which is used to connect an electrical connector and then connect two external circuits, thereby enabling switching between the two external circuits.

[0054] like Figure 5 As shown, preferably, the proximity switch provided in this embodiment further includes three elastic sleeves 23, which are respectively sleeved on the right end of the three terminals 21, i.e., the end facing the opening of the outer cylinder 1. It is easy to understand that the elastic sleeves 23 are made of conductive material, and by setting the elastic sleeves 23, the conductive component 2 and the electrical connector can be in a connected state.

[0055] like Figure 1 As shown, the proximity switch provided in this embodiment also includes a clamping nut 6. The clamping nut 6 is disposed inside the outer cylinder 1 and threadedly connected to the outer cylinder 1. Specifically, the clamping nut 6 is formed into a ring structure and is located between the conductive component 2 and the right end (open end) of the outer cylinder 1. The left end of the clamping nut 6 abuts against the base 22 of the conductive component 2, and the right end of the terminal 21 of the conductive component 2 can extend to the right from the inside of the ring structure. By providing the clamping nut 6, the conductive component can be prevented from coming out of the open end (right end) of the outer cylinder 1.

[0056] Example 2

[0057] Based on Embodiment 1, this embodiment also provides a valve warning system, including a valve, a bracket, an electrical connector, an alarm, and the proximity switch from Embodiment 1.

[0058] A third magnetic component is provided on the valve stem. The end of the third magnetic component facing the first magnetic component has the same magnetism as the end of the second magnetic component facing the first magnetic component. In this embodiment, there are no restrictions on the way the third magnetic component is fixed to the valve stem. Those skilled in the art can make the setting according to actual needs.

[0059] Both the valve and the proximity switch are mounted on the bracket. The alarm is electrically connected to the second and third terminals of the proximity switch via electrical connectors. For example, the micro-touch switch located below can control the connection state of the circuit in which the alarm is located.

[0060] One possible implementation is that the electrical connector includes a socket, the main body of which is fixedly connected to the open end of the outer cylinder, and the pins of the socket are connected to the terminals of the conductive component via an elastic sleeve.

[0061] Those skilled in the art will understand that when the valve changes from the open state to the closed state, the valve stem drives the third magnetic component to move closer to the proximity switch. Under the magnetic force of the third magnetic component, the first magnetic component drives the cam to rotate, triggering the micro-touch switch located below, connecting the circuit of the alarm and issuing an alarm.

[0062] The proximity switch in this embodiment has the same structure as the proximity switch provided in Embodiment 1, and can bring the same or similar technical effects. It will not be described in detail here. For details, please refer to the description of the above embodiments.

[0063] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0064] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A proximity switch, characterized in that, include: The outer cylinder includes an open end and a closed end; A conductive component, disposed inside the outer cylinder and near the opening end of the outer cylinder, is used to connect electrical connectors; The drive assembly includes a first magnetic element, a second magnetic element, a cam, and a rotating shaft. The rotating shaft is rotatably mounted inside an outer cylinder, and the axis of the rotating shaft is perpendicular to the central axis of the outer cylinder. The cam is fitted onto the rotating shaft, and two actuating parts are spaced apart on the side of the cam. The shaft hole of the cam has a receiving groove in its wall, and the first magnetic element is installed in the receiving groove and can drive the cam to rotate. The second magnetic element is fixed inside the outer cylinder and located between the first magnetic element and the conductive component. A contact assembly is disposed inside the outer cylinder and located between the cam and the second magnetic element, the contact assembly comprising two microswitches; When the cam rotates to a first angle, one of the actuating parts of the cam can trigger one of the micro-touch switches; when the cam rotates to a second angle, the other actuating part of the cam can trigger another micro-touch switch. A washer is provided at the large-diameter end of the shaft hole, and the washer and the hole wall of the shaft hole define a receiving groove for accommodating the first magnetic component. The two micro-touch switches are arranged at an axial distance from each other along the cam. It also includes a mounting base, which is disposed inside the outer cylinder and fixed to the outer cylinder. Both ends of the rotating shaft pass through the mounting base, and the mounting base is provided with mounting holes coaxial with the outer cylinder. The second magnetic component is fixed in the mounting holes. The conductive component includes three terminals and a base. The three terminals pass through the base, and one end of the three terminals facing the second magnetic component is electrically connected to the two micro-touch switches. It also includes a clamping nut, which is disposed inside the outer cylinder and threadedly connected to the outer cylinder, and the clamping nut is located between the conductive component and the open end of the outer cylinder.

2. The proximity switch according to claim 1, characterized in that, The receiving groove is an annular groove surrounding the rotating shaft, and the first magnetic component is a magnetic ring made of magnetic core material.

3. The proximity switch according to claim 2, characterized in that, The magnetic ring is a closed shape.

4. The proximity switch according to claim 2, characterized in that, The magnetic ring has a semi-closed shape.

5. The proximity switch according to claim 1, characterized in that, It also includes three elastic sleeves, which are respectively fitted onto the ends of the three terminals facing the opening of the outer cylinder.

6. A valve early warning system, characterized in that, Includes valves, brackets, electrical connectors, alarms, and proximity switches as described in any one of claims 1 to 5; The valve stem is provided with a third magnetic element, the valve and the proximity switch are mounted on the bracket, and the alarm is electrically connected to the terminal block of the proximity switch base through the electrical connector.

Images