A proximity switch and method of assembly thereof

Abstract

The application discloses a proximity switch, characterized in that the proximity switch comprises a hollow outer shell and a plug body which are coaxially sleeved, and a shielding ring is arranged on the plug body; a main control circuit board is arranged in the hollow part of the outer shell, a magnetic core is arranged at one end of the main control circuit board close to the plug body, the magnetic core is located in the plug body, and the magnetic core, the shielding ring and the plug body are coaxially arranged; a center hole is formed in the magnetic core, a positioning column is arranged in the plug body, and the positioning column is sleeved with the center hole. The application further provides an assembling method of the proximity switch. In the application, the shielding ring is added, so that the debugging frequency is reduced, the influence of various metal shells on the product distance is reduced, the product consistency is improved, the debugging resistance value range is reduced, the success rate of laser adjustment is improved, the automatic production in the later period is facilitated, the finished product inventory is reduced, and the production cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of sensor technology and relates to a proximity switch and its assembly method. Background Technology

[0002] A proximity switch is a position switch that operates without direct mechanical contact with moving parts. When an object approaches the sensing surface of the switch to the operating distance, the switch actuates without mechanical contact or pressure, thereby driving DC electrical appliances or providing control commands to computer (PLC) devices. A proximity switch is a type of switch-type sensor (i.e., a contactless switch). It combines the characteristics of limit switches and microswitches with sensing capabilities, offering reliable operation, stable performance, fast frequency response, long service life, strong anti-interference ability, and features such as waterproofing, shockproofing, and corrosion resistance. Products are available in inductive, capacitive, Hall effect, AC, and DC types.

[0003] Proximity switches, also known as non-contact proximity switches, are ideal electronic switching sensors. When a metal object approaches the switch's sensing area, the switch can quickly issue an electrical command without contact, pressure, or sparks, accurately reflecting the position and stroke of the moving mechanism. Even for general stroke control, its positioning accuracy, operating frequency, service life, ease of installation and adjustment, and adaptability to harsh environments are unmatched by ordinary mechanical limit switches. They are widely used in machine tools, metallurgy, chemical, textile, and printing industries. In automatic control systems, they can be used as limit switches, counters, positioning controls, and automatic protection components.

[0004] Proximity switches work by adjusting the current in a coil to change the magnetic field strength, using the eddy current effect to detect the presence of a metallic object. Therefore, according to national or industry standards, the detection distance of a proximity switch needs to be set to a specific value. Currently, the common method is to change the resistance value on the control board, thereby altering the current flowing through the coil and setting the distance. Therefore, each proximity sensor requires a suitable resistance value to calibrate the detection distance of the proximity switch.

[0005] Currently, there are three main methods for changing resistance values: directly replacing the resistor with a suitable value, adjusting it with a potentiometer, and adjusting the thick-film resistor using laser technology. Each method has its advantages and disadvantages, but all share a common drawback: the magnetic field of the core coil is affected by the material of the metal casing, impacting the calibrated distance. The distance adjusted externally by the core coil will change after assembly inside the metal casing, requiring multiple adjustments to achieve the desired distance. This leads to low production efficiency. Furthermore, different metal materials have different effects; for example, stainless steel, zinc alloy, and copper tubing all have different influences, resulting in product inconsistencies. Different metal casings require adjustments to the corresponding material parameters, necessitating different solutions for mass production. Secondly, if the detection distance needs to be increased to double or even triple the original distance, the influence of the metal casing on the magnetic field will double, multiplying the difficulty of product adjustment and the defect rate. Summary of the Invention

[0006] The purpose of this invention is to provide a proximity switch that reduces the influence of the metal casing on the magnetic field and thus the distance adjustment by setting a shielding ring, thereby enabling accurate and rapid acquisition of the required resistance on the main control board.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a proximity switch, characterized in that it comprises a hollow outer shell and a plug that are nested together, wherein a shielding ring is provided on the plug.

[0008] The present invention further provides that the hollow portion of the outer shell is provided with a main control circuit board, and a magnetic core is provided at one end of the main control circuit board near the plug body. The magnetic core is located inside the plug body, and the magnetic core, the shielding ring and the plug body are coaxially arranged.

[0009] The present invention further includes a central hole formed on the magnetic core, and a positioning post disposed inside the plug body, the positioning post being sleeved with the central hole.

[0010] The present invention further provides that the outer casing includes a protective layer, a shielding layer and an insulating layer arranged sequentially from the outside to the inside, and the main control circuit board is located within the insulating layer.

[0011] The present invention further comprises a magnetic core including a mounting base and a magnetic core body, the magnetic core body being placed in a corresponding mounting base, the mounting base being located at one end of the outer shell, the mounting base having a mounting cavity, the mounting cavity having a mounting post, the central hole being located at the center of the mounting post, and the magnetic core body being sleeved on the mounting post.

[0012] In a further embodiment of the present invention, one end of the main control circuit board forms an extension block, which extends into the central hole and connects to the magnetic core.

[0013] The present invention also provides a method for assembling a proximity switch, wherein a shielding ring is embedded in a plug body through a precision mold, a magnetic core with a main control circuit board is inserted into the plug body through the action of a positioning post and a central hole, the plug body is then potted with epoxy resin, the resistance value on the main control circuit board is adjusted according to the distance requirement, and after determination, the outer shell is connected to the plug body and encapsulated with epoxy resin.

[0014] The beneficial effects of this invention are as follows: Adding a shielding ring reduces the number of adjustments required and minimizes the impact of various metal casings on product distance; it also improves product consistency and narrows the range of adjustment resistor values. Furthermore, it increases the success rate of laser trimming, facilitates automated production, reduces finished product inventory, and lowers production costs. Attached Figure Description

[0015] Figure 1 This is a perspective view of an embodiment of the present invention.

[0016] Figure 2 This is a cross-sectional view of an embodiment of the present invention after the outer shell has been removed.

[0017] Figure 3 This is an exploded view of an embodiment of the present invention.

[0018] Reference numerals: 10, outer casing; 20, plug; 201, positioning post; 30, shielding ring; 40, magnetic core; 401, mounting base; 402, magnetic core body; 4011, mounting cavity; 4012, mounting post; 4012a, center hole; 50, main control circuit board; 501, extension block; 60, protective layer; 70, shielding layer; 80, insulating layer; Detailed Implementation

[0019] The following will describe the implementation of this application in detail with reference to the embodiments, so that the implementation process of how this application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0020] like Figure 1-3As shown, this invention relates to a proximity switch, comprising a hollow outer shell 10 and a plug 20 that are nested together. The plug 20 is provided with a shielding ring 30. In the prior art, traditional plugs do not have a shielding ring 30, which alters the distance after assembly. The conventional method involves assembling the plug 20 first, then extending the coil lead beyond the metal shell for adjustment. This method has drawbacks: firstly, the coil lead is too long, causing interference; secondly, the coil lead is not fixed and is prone to breakage during assembly; and thirdly, the excessively long coil lead may adhere to the metal shell during assembly, affecting the adjustment of the calibrated distance. Therefore, this application incorporates a shielding ring 30, which avoids the problem of altered calibrated distance.

[0021] Secondly, in order to further improve the reliability of the calibration distance and reduce the distance error caused by the cumulative error of the magnetic core 40 coil, the precision error of electronic components, the size error of the metal shell, and the spacing error between the magnetic core 40 and the metal shell, the following technical solution is adopted: The hollow part of the outer shell 10 is provided with a main control circuit board 50, and the magnetic core 40 is provided at one end of the main control circuit board 50 near the plug body 20. The magnetic core 40 is located inside the plug body 20, and the magnetic core 40, the shielding ring 30 and the plug body 20 are coaxially arranged. A central hole 4012a is formed on the magnetic core 40. A positioning post 201 is provided inside the plug body 20, and the positioning post 201 is sleeved with the central hole 4012a. The outer shell 10 includes a protective layer 60, a shielding layer 70 and an insulating layer 80 arranged sequentially from the outside to the inside. The main control circuit board 50 is located inside the insulating layer 80.

[0022] In the above technical solution, a positioning post 201 is provided inside the plug of the present invention, which can keep the distance between the edge of the magnetic core 40 and the shielding ring 30 consistent. The shielding ring 30 is embedded in the plastic by a precision mold, which solves the uncertainty of the distance effect caused by the assembly position deviation of the magnetic core 40.

[0023] The magnetic core 40 includes a mounting base 401 and a magnetic core 40 body. The magnetic core 40 body is placed in the corresponding mounting base 401. The mounting base 401 is located at one end of the outer shell 10. A placement cavity 4011 is formed on the mounting base 4011. A mounting post 4012 is formed on the placement cavity 4011. The central hole 4012a is located at the center of the mounting post 4012. The magnetic core 40 body is sleeved on the mounting post 4012. An extension block 501 is formed at one end of the main control circuit board 50. The extension block 501 extends into the central hole 4012a and connects to the magnetic core 40.

[0024] Furthermore, inductive proximity switches are typically potted with epoxy resin to enhance their waterproofing and protection level. Because epoxy resin has a certain coefficient of thermal expansion, this expansion will cause some deformation of the coil, ultimately resulting in a change in distance after potting. Based on existing product structures, if the distance changes after epoxy potting, it cannot be adjusted again. If the adjustment method described above is followed, and the distance change is too large after epoxy potting, the product will be unusable. Adding a 30mm shielding ring allows for pre-potting of the plug, enabling distance adjustment and thus avoiding this problem.

[0025] Overall: With the addition of the shielding ring 30, since it can be adjusted beforehand and the distance will not change after assembly, it can be equipped with automated equipment for automated adjustment, which greatly improves production efficiency.

[0026] Based on the above technical solution, the present invention also provides an assembly method for a proximity switch. The shielding ring 30 is embedded in the plug body 20 through a precision mold. The magnetic core 40 with the main control circuit board 50 is installed into the plug body 20 through the action of the positioning post 201 and the center hole 4012a. Then, the plug body 20 is potted with epoxy resin. Subsequently, the resistance value on the main control circuit board 50 is adjusted according to the distance requirement. After determination, the outer shell 10 is connected to the plug body 20 and encapsulated with epoxy resin.

[0027] The addition of a shielding ring 30 in this invention reduces the number of adjustments required and minimizes the impact of various metal casings on product distance; it also improves product consistency and narrows the range of adjustment resistor values. Furthermore, it increases the success rate of laser trimming, facilitates automated production later on, reduces finished product inventory, and lowers production costs.

[0028] The specification and claims use certain terms to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This specification and claims do not distinguish components based on differences in name, but rather on differences in function. The term "comprising" throughout the specification and claims is an open-ended term and should be interpreted as "comprising but not limited to." "Approximately" means that within an acceptable margin of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect within a certain margin of error.

[0029] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the product or system that includes said element.

[0030] The foregoing description illustrates and describes several preferred embodiments of the present invention. However, as previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A proximity switch, characterized in that, It includes a hollow outer shell and a plug that are nested together, and the plug is provided with a shielding ring; The hollow portion of the outer shell is provided with a main control circuit board, and a magnetic core is provided at one end of the main control circuit board near the plug body. The magnetic core is located inside the plug body, and the magnetic core, the shielding ring, and the plug body are coaxially arranged. A central hole is formed on the magnetic core, and a positioning post is provided inside the plug body, with the positioning post sleeved with the central hole; The outer casing includes a protective layer, a shielding layer, and an insulating layer arranged sequentially from the outside to the inside, and the main control circuit board is located inside the insulating layer; The magnetic core includes a mounting base and a magnetic core body. The magnetic core body is placed in the corresponding mounting base. The mounting base is located at one end of the outer shell. A placement cavity is formed on the mounting base. A mounting post is formed on the placement cavity. The central hole is located at the center of the mounting post. The magnetic core body is sleeved on the mounting post. One end of the main control circuit board forms an extension block, which extends into the central hole and connects to the magnetic core. The aforementioned proximity switch assembly process includes: embedding the shielding ring into the plug body using a precision mold; inserting the magnetic core with the main control circuit board into the plug body using the positioning post and center hole; encapsulating the plug body with epoxy resin; adjusting the resistance value on the main control circuit board according to the distance requirements; connecting the outer shell to the plug body and encapsulating it with epoxy resin.

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