Piston magnetizer position detection device

Abstract

The utility model discloses a piston magnetizer position detection device which comprises a shell, a piston, a magnetizer and a coil. The front and rear ends of the shell respectively form openings; the front section is provided with a piston which moves under the action of driving force, a piston reset spring is arranged between the shell and the piston, the front end of the piston is provided with a testing head for detecting a tested object, the testing head extends out of an opening in the front end of the shell, and a magnetizer is fixed at the rear end of the piston; the rear section of the shell is provided with a coil; the magnetizer is arranged in the coil in a penetrating mode and driven by the piston to move in the coil. When the driving force acts on the piston, the inductance of the coil changes when the piston drives the magnetizer to move in the coil, and the specific position of the measured object can be obtained by measuring the inductance change of the coil through the detector. According to the utility model, the appearance is reduced, the processing and the design are convenient, temporary assembly is not needed, the device can be used in a compact structure, the specific position of a detected object can be obtained, and the detection is convenient and rapid.

Description

Technical Field

[0001] This utility model relates to a detection device, and more particularly to a piston magnetic conductor position detection device. Background Technology

[0002] To detect the presence of the analyte, existing technology uses... Figure 1 As shown, the switch test probe assembly 200 is mounted on the slider 300, which is mounted on the front end of the push rod of the cylinder 100. The switch test probe assembly 200 has a needle core 210, a tail needle 220, an insulator 230, and an outer sleeve 240. The outer sleeve 240 is fixed to the slider 300 and has a central hole 241. The needle core 210 and the tail needle 220 are inserted into the central hole 241. The rear end of the needle core 210 and the front end of the tail needle 220 are located inside the central hole 241, and a spring 250 is provided between them. The front end of the needle core 210 and the rear end of the tail needle 220 extend out of the central hole 241, and the needle core 210 contacts the outer sleeve 240. An insulator 230 is provided between the tail needle 220 and the outer sleeve 240.

[0003] In the prior art, both the tail needle 220 and the outer sleeve 240 are connected to the detection circuit (not shown in the figure) via wires. When the cylinder 100 pushes the slider 300, the switch test needle assembly 200 moves forward and approaches the object under test 400. The needle core 210 is compressed backward, so that the needle core 210 touches the tail needle 220. Since the outer sleeve 240, the needle core 210, and the tail needle 220 are all conductive objects, the needle core 210 makes the tail needle 220 and the outer sleeve 240 conductive, thus forming a circuit, thereby proving the existence of the object under test 400.

[0004] It is easy to see that existing technologies are large in size, inconvenient to process and design, require temporary assembly, cannot be used in compact structures, and can only detect the presence or absence of an object, not its specific position. Therefore, improvement is necessary. In view of this, the inventor, drawing on extensive experience accumulated over many years in the field of detection devices, has conducted in-depth research on existing detection devices and developed a piston magnetic conductor position detection device, thus giving rise to this invention. Utility Model Content

[0005] The purpose of this invention is to provide a piston magnetic conductor position detection device that is smaller in size, easier to process and design, requires no temporary assembly, can be used in a compact structure, and can obtain the specific position of the object being measured, making detection convenient and fast.

[0006] To achieve the above objectives, the solution of this utility model is:

[0007] A piston-magnetic conductor position detection device includes a housing, a piston, a magnetic conductor, and a coil. Openings are formed at both the front and rear ends of the housing. A piston, which moves under the action of a driving force, is located at the front end of the housing. A piston return spring is positioned between the housing and the piston. A test head for detecting the object under test is located at the front end of the piston, extending from the opening at the front end of the housing. The magnetic conductor is fixed at the rear end of the piston. A coil is installed at the rear end of the housing. The magnetic conductor passes through the coil and moves within the coil, driven by the piston. In use, when the driving force acts on the piston, the piston compresses the piston return spring, causing it to move. Simultaneously, the piston moves the magnetic conductor. As the magnetic conductor moves within the coil, the inductance of the coil changes. By measuring the inductance or resonant frequency change of the coil using a detector, the specific position of the magnetic conductor can be obtained, thus determining the specific position of the object under test.

[0008] Furthermore, the object to be tested by the device is fixed. An air inlet is provided on the outer shell to allow compressed air to enter the shell and drive the piston to move. The driving force for the piston to move is the compressed air entering the shell through the air inlet. A sealing ring is provided between the piston and the shell to ensure airtightness. Under normal conditions, the piston return spring causes the piston and the test head to move back into the shell to reset. The piston moves forward under the action of compressed air, driving the test head forward until it touches the object to be tested.

[0009] Furthermore, the device targets a moving object, and the piston generates a driving force for the moving object. Under normal conditions, the piston return spring causes the piston and test head to move and reset towards the front end of the housing, and the piston moves backward under the action of the moving object.

[0010] In one optimized design, the front end of the piston forms a push rod, and the front end of the push rod directly forms a test head, such as a flat test head or a hemispherical test head. Alternatively, in another optimized design, the front end of the piston is equipped with a spherical test head, and the diameter of the front opening of the outer shell is smaller than the diameter of the spherical test head. Most of the test head is confined within the outer shell, while a small portion protrudes from the front opening. Yet another optimized design involves the front end of the piston forming a push rod with internal threads, allowing connection to various test heads to accommodate different test objects.

[0011] Furthermore, a circuit board is installed at the rear of the housing, and the coil leads are connected to the circuit board.

[0012] Furthermore, the circuit board extends from the side of the housing; or, the circuit board extends along the axial direction of the housing.

[0013] Furthermore, the rear section of the housing is fixed with a coil bracket, the rear end of the coil bracket is fixed with a circuit board, and the coil is mounted on the coil bracket; or, the rear section of the housing is fixed with a coil bracket, the rear end of the coil bracket is fixed with a circuit board, the coil is mounted on the coil bracket, a base is added between the coil bracket and the circuit board, the front side of the base is fixed to the coil bracket and the rear side is fixed with the circuit board, the base forms an extension tube corresponding to the center hole of the coil bracket for the magnetic conductor to extend into, the extension tube is inserted into the center hole of the coil bracket and abuts against the coil to fix the coil; or, the rear section of the housing is fixed with a bushing, a tailstock and an insulating sleeve, the coil is fixed in the housing by means of the bushing and the tailstock, and the circuit board is fixed in the housing by means of the insulating sleeve.

[0014] Furthermore, the front opening of the outer shell is constricted, while the rear opening is open; the rear end of the outer shell is covered with an insulating wrapping body, which fixes the coil and the circuit board to the rear end of the outer shell, and the insulating wrapping body forms a circuit board through hole corresponding to the circuit board; or the insulating wrapping body forms an air nozzle corresponding to the air inlet of the outer shell.

[0015] Furthermore, a capacitor is connected in parallel to both ends of the coil leads on the circuit board, and the capacitor is soldered to the circuit board, forming an LC oscillator with the coil; alternatively, a capacitor is connected in parallel to both ends of the coil leads, and a test instrument is also connected in parallel; the capacitor can eliminate the influence of the connection line between the test instrument and this device, allowing the coil to have a stable resonant frequency. Alternatively, the test instrument is connected in parallel to both ends of the coil leads. Alternatively, the circuit board also has pads for connecting external leads to the test instrument.

[0016] By adopting the above solution, this utility model integrates the magnetic conductor and the testing component together, eliminating the need for an external cylinder. During use, air can be supplied simply by connecting the air inlet to an air pump; when not in use, the connection can be removed. The overall size of the device is greatly reduced, facilitating processing and design. It eliminates the need for temporary assembly of a large cylinder, allowing the compact device to be used within a small structure, making operation very convenient and quick. Furthermore, when the driving force acts on the piston, the magnetic conductor, driven by the piston, moves within the coil, causing a change in the coil's inductance. By measuring the coil's inductance value or the change in the resonant frequency formed by the coil and capacitor with a detector, the specific position of the magnetic conductor can be obtained, thus revealing the specific position of the object being tested.

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model, the accompanying drawings used in the description of the embodiments are briefly described below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a three-dimensional exploded view of the existing detection device;

[0020] Figure 2 This is a structural schematic diagram of Embodiment 1 of the present invention;

[0021] Figure 3 This is a schematic diagram of the structure of Embodiment 2 of this utility model;

[0022] Figure 4 This is a structural schematic diagram of Embodiment 3 of this utility model;

[0023] Figure 5 This is a structural schematic diagram of Embodiment 4 of this utility model;

[0024] Figure 6 This is a structural schematic diagram of Embodiment 5 of this utility model;

[0025] Figure 7 This is a structural schematic diagram of Embodiment Six of this utility model;

[0026] Figure 8 This is a structural schematic diagram of Embodiment Seven of this utility model;

[0027] Figure 9 This is a structural schematic diagram of Embodiment 8 of this utility model.

[0028] Label Explanation

[0029] 100----Cylinder, 200----Switch test probe assembly, 210----Needle core, 220----Tail needle, 230----Insulator, 240----Outer jacket, 241----Center hole, 250----Spring, 300----Slider, 400----Object under test;

[0030] 1----Outer shell, 11----Air inlet, 12----Sealing ring, 13----Step;

[0031] 2----piston, 21----piston return spring, 22----internal thread;

[0032] 3----Magnetic conductor;

[0033] 4----coil, 41----shroud, 42----tailstock;

[0034] 5----Test Head;

[0035] 6----coil bracket, 61----positioning post;

[0036] 7----Circuit board, 71----Insulating sleeve;

[0037] 8----Insulation wrapping, 81----Air nozzle, 82----Circuit board perforation;

[0038] 9----base, 91----extension tube, 92----positioning post. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, not all of them. Therefore, the following detailed description of the embodiments of this utility model provided in the accompanying drawings is not intended to limit the scope of the claimed utility model, but merely to represent selected embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without inventive effort are within the scope of protection of this utility model.

[0040] It should be noted that the terms front, back, inside, outside, top, bottom, left, right, first, second, third, etc. are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the technical features indicated, unless otherwise explicitly defined.

[0041] This article defines the direction closer to the inspection station as "front" and the direction farther from the inspection station as "back". The terms "front" and "back" are only relative positions and are used to facilitate the description of the structure, not as a limitation on the technical solution. The front and back can be interchanged without affecting the overall structure.

[0042] like Figures 2 to 9 As shown, this utility model discloses a piston magnetic conductor position detection device, including a housing 1, a piston 2, a magnetic conductor 3, and a coil 4.

[0043] The front and rear ends of the outer shell 1 are respectively formed with openings.

[0044] A piston 2 is provided at the front end of the outer casing 1. The piston 2 moves under the action of a driving force, which can be from the inside of the outer casing 1 to the outside or from the outside to the inside of the outer casing 1. A piston return spring 21 is provided between the outer casing 1 and the piston 2. The front end of the piston 2 has a test head 5, which extends from the front opening of the outer casing 1. The test head 5 is used to detect the object under test 400.

[0045] The piston 2 has a fixed magnetic conductor 3 at its rear end, such as iron, nickel-iron alloy, manganese-zinc alloy, nickel-zinc alloy, ferrite, etc.

[0046] The rear section of the outer casing 1 is fixed with a coil bracket 6, and the rear end of the coil bracket 6 is fixed with a circuit board 7. Specifically, the coil bracket 6 can be fixed to the circuit board 7 by two positioning posts 61. The coil 4 is mounted on the coil bracket 6, and the lead wire of the coil 4 is connected to the circuit board 7. Of course, in this invention, the coil 4 and the circuit board 7 can also be directly fixed and mounted on the rear section of the outer casing 1, omitting the coil bracket 6, which is not shown in the figure.

[0047] The magnetic conductor 3 is inserted into the coil 4, and the piston 2 drives the magnetic conductor 3 to move within the coil 4.

[0048] This invention further includes a capacitor (a common component, not shown in the figure) connected in parallel to both ends of the coil 4 leads on the circuit board 7. The capacitor is soldered onto the circuit board 7, and the capacitor and coil 4 form an LC oscillator, eliminating the influence of the connection lines between the detector and this device, thus enabling coil 4 to have a stable resonant frequency. Additionally, this invention further includes solder pads (a common component, not shown in the figure) on the circuit board 7 for connecting external leads to the tester, facilitating testing.

[0049] In operation, the circuit board 7 is directly connected to the detection circuit (not shown in the figure), making the connection more convenient and faster. When the driving force is applied to the piston 2, the piston 2 compresses the piston return spring 21 to generate movement. The moving piston 2 simultaneously drives the magnetic conductor 3 to move as well. When the magnetic conductor 3 moves in the coil 4, the inductance of the coil 4 changes. By measuring the inductance value of the coil 4 or the change in the resonant frequency formed by the coil and capacitor with the detector, the specific position of the magnetic conductor 3 can be obtained, thereby obtaining the specific position of the object under test 400.

[0050] like Figure 2As shown, the device described in Embodiment 1 of this utility model targets a fixed test object 400. An air inlet 11 is provided on the outer casing 1 to allow compressed air to enter the casing 1 and drive the piston 2. The driving force for the piston 2 to move is the compressed air entering the casing 1 through the air inlet 11. A sealing ring 12 (O-ring or V-ring) can be further provided between the piston 2 and the casing 1 to ensure airtightness, thereby ensuring the effective action of compressed air on the piston 2 during operation. Under normal conditions, the piston return spring 21 causes the piston 2 and the test head 5 to move back into the casing 1. Under the action of compressed air, the piston 2 squeezes the piston return spring 21 and moves forward, driving the test head 5 forward until it touches the test object 400.

[0051] In Embodiment 1, the front end of the piston 2 forms a push rod, which directly serves as the test head 5. Alternatively, the push rod may have an internal thread 22 for connecting various test heads (not shown in the figure) to accommodate different test objects 400.

[0052] For ease of assembly, the front opening of the outer shell 1 in Embodiment 1 is constricted, while the rear opening is open. The two ends of the piston return spring 21 abut against the front end of the outer shell 1 and the front end of the piston 2. The rear end of the outer shell 1 is covered with an insulating wrapper 8, which fixes the coil 4, coil support 6 and circuit board 7 to the rear end of the outer shell 1. Alternatively, a step 13 can be formed in the outer shell 1, which, together with the insulating wrapper 8, fixes the coil 4, coil support 6 and circuit board 7. The insulating wrapper 8 further forms an air nozzle 81 corresponding to the air inlet 11 of the outer shell 1, and a circuit board through hole 82 corresponding to the circuit board 7.

[0053] In the first embodiment, air is supplied by connecting the air inlet 11 to the air pump. Compressed air is delivered to the outer casing 1 through the air inlet 11. The piston 2 is pushed forward by the compressed air to move towards the test object 400. The piston 2 moves along with the magnetic conductor 3 and the test head 5. When the test head 5 touches the test object 400, it stops moving. At the same time, the magnetic conductor 3, which is moved along with the piston 2, moves in the coil 4, causing a change in the inductance of the coil 4. By measuring the change in the inductance or resonant frequency of the coil 4 with a detector, the specific position of the magnetic conductor 3 can be obtained, thereby obtaining the specific position of the test object 400.

[0054] Also, such as Figure 3As shown, in Embodiment 2 of this utility model, the test object 400 is also fixed, just like in Embodiment 1. The driving force for the piston 2 to move is compressed air entering the outer casing 1 through the air inlet 11. The main structures of Embodiment 1 and Embodiment 2 are the same, except that in Embodiment 2, the coil 4 is shorter, while the length of the outer casing 1 is the same as in Embodiment 1. Therefore, a base 9 is added between the coil support 6 and the circuit board 7. The front side of the base 9 is fixed to the coil support 6, and the rear side is fixed to the circuit board 7. Specifically, the coil support 6 and the base 9 can be fixed by two positioning posts 61, and the base 9 and the circuit board 7 can also be fixed by two positioning posts 92. The base 9 forms an extension tube 91 corresponding to the center hole of the coil support 6 for the insertion of the magnetic conductor 3. The extension tube 91 is inserted into the center hole of the coil support 6 and abuts against the coil 4 to fix the coil 4. The coil 4, coil support 6, base 9 and circuit board 7 are then fixed to the rear end of the outer casing 1 by means of the insulating wrapping body 8. Similar to Embodiment 1, this second embodiment also forms a step 13 in the outer casing 1. The step 13, together with the insulating wrapping body 8, fixes the coil 4, coil support 6, base 9 and circuit board 7.

[0055] The working principle of Example 2 is the same as that of Example 1, and will not be repeated here.

[0056] Furthermore, such as Figure 4 As shown, the device described in Embodiment 3 of this utility model targets a horizontally moving object 400, with the direction of movement indicated by the arrow. The piston 2 generates the driving force for the moving object 400 outside the outer casing 1. Under normal conditions, the piston return spring 21 causes the piston 2 and the test head 5 to move back to the front end of the outer casing 1. Under the action of the moving object 400, the piston 2 moves backward (inside the outer casing 1). Specifically, the front end of the piston 2 forms a push rod, which directly serves as the test head 5. Alternatively, the push rod may have internal threads for connecting various test heads (not shown in the figure) to accommodate different objects 400. The front opening of the outer casing 1 is constricted, while the rear opening is open. The two ends of the piston return spring 21 abut against the piston 2 and the coil support 6. The rear end of the outer casing 1 is covered with an insulating wrapping body 8, which fixes the coil 4, the coil support 6 and the circuit board 7 to the rear end of the outer casing 1. Alternatively, a step 13 can be formed in the outer casing 1, which, together with the insulating wrapping body 8, fixes the coil 4, the coil support 6 and the circuit board 7. The insulating wrapping body 8 further forms a circuit board through hole 82 corresponding to the circuit board 7.

[0057] In Example 3, the test head 5 is first brought into contact with the object under test 400. When the object under test 400 moves horizontally, it pushes the piston 2 into the outer shell 1. The piston 2 squeezes the piston return spring 3. At the same time, the piston 2 drives the magnetic conductor 3 to move together. When the magnetic conductor 3 moves in the coil 4, it causes the inductance of the coil 4 to change. By measuring the inductance or resonant frequency change of the coil 4 with a detector, the specific position of the magnetic conductor 3 can be obtained, thereby obtaining the specific position of the object under test 400.

[0058] Additionally, such as Figure 5 and Figure 6 As shown, the devices described in Embodiments 4 and 5 of this utility model target test objects 400 that move vertically, with the direction of movement as indicated by the arrows. The driving force generated by the piston 2 is the moving test object 400 outside the outer shell 1. Embodiments 4 and 5 have the same main structure as Embodiment 3, the difference being that: in Embodiment 4, the front end of the piston 2 forms a push rod, and the front end of the push rod directly forms a hemispherical test head 5; in Embodiment 5, the front end of the piston 2 is equipped with a spherical test head 5, the diameter of the front opening of the outer shell 1 is smaller than the diameter of the spherical test head 5, most of the test head 5 is confined in the outer shell 1 and will not come out, while a small part of the test head 5 protrudes from the front opening of the outer shell 1. The hemispherical test head 5 in Embodiment 4 and the spherical test head 5 in Embodiment 5 can reduce the frictional force between the test object 400 and the moving test object, making the testing work smoother.

[0059] The working principle of Examples 5 and 6 is similar to that of Example 3. First, the test head 5 touches the object under test 400. When the object under test 400 moves vertically downward, it pushes the piston 2 into the outer shell 1. The piston 2 squeezes the piston return spring 3. At the same time, the piston 2 drives the magnetic conductor 3 to move together. When the magnetic conductor 3 moves in the coil 4, it causes the inductance of the coil 4 to change. By measuring the inductance or resonant frequency change of the coil 4 with the detector, the specific position of the magnetic conductor 3 can be obtained, thereby obtaining the specific position of the object under test 400.

[0060] Also, such as Figures 7 to 9 As shown, the devices described in embodiments six, seven, and eight of this utility model are similar to those in embodiment three, all targeting a horizontally moving test object 400, with the direction of movement as indicated by the arrows. The piston 2 generates the driving force for the movement of the test object 400, which moves outside the outer casing 1. Under normal conditions, the piston return spring 21 causes the piston 2 and the test head 5 to move back towards the front end of the outer casing 1. The piston 2 moves backward (inside the outer casing 1) under the action of the moving test object 400. Specifically, the front end of the piston 2 forms a push rod, which directly serves as the test head 5. Figures 7 to 9Three different test heads 5 are shown to accommodate different test objects 400. One end of the piston return spring 21 rests against the piston 2, and the other end rests directly or indirectly against the housing 1. As shown in the figure, the coil 4 is fixed in the housing 1 by means of a bushing 41 and a tailstock 42. The bushing 41 guides the magnetic conductor 3, allowing it to enter the coil 4 more accurately. The circuit board 7 is fixed in the housing 1 by means of an insulating sleeve 71, and the other end of the piston return spring 21 rests against the bushing 41 (i.e., indirectly against the housing 1).

[0061] The working principle of Examples 6, 7, and 8 is the same as that of Example 3. After the test head 5 touches the test object 400, the test object 400 moves horizontally and pushes the piston 2 into the outer shell 1. The piston 2 squeezes the piston return spring 21. At the same time, the piston 2 drives the magnetic conductor 3 to move together. When the magnetic conductor 3 moves in the coil 4, it causes the inductance of the coil 4 to change. By measuring the inductance or resonant frequency change of the coil 4 with the detector, the specific position of the magnetic conductor 3 can be obtained, thereby obtaining the specific position of the test object 400.

[0062] It should be noted that the circuit board 7 can also be omitted in this utility model, and the coil 4 can be directly connected to the detection circuit through the lead wire. Its working principle is the same as that of the aforementioned embodiments, and will not be illustrated or described in detail in this article.

[0063] The different extension methods of the circuit board 7 described in this utility model can be used to place it on working surfaces of different sizes. In embodiments one to five, the circuit board 7 extends from the side of the outer shell 1. In embodiments six to eight, the circuit board 7 extends along the axial direction of the outer shell 1, making the overall width slender, the structure more compact, the working surface smaller, and adapting to the miniaturization requirements of the test module.

[0064] The embodiments described above are only for illustrating the technical ideas and features of this utility model. Their purpose is to enable those skilled in the art to understand the content of this utility model and implement it accordingly, but they do not limit the patent scope of this utility model. All equivalent changes or modifications made in accordance with the spirit disclosed in this utility model should still be covered within the patent scope of this utility model.

Claims

1. A piston pole piece position detection apparatus characterized by: The device comprises a shell, a piston, a magnetic conductor and a coil; the front and rear ends of the shell are respectively formed with openings; the front section of the shell is provided with the piston which is moved by a driving force; a piston return spring is arranged between the shell and the piston; the front end of the piston is provided with a testing head for detecting a measured object; the testing head extends out of the front end opening of the shell; and the rear end of the piston is fixed with the magnetic conductor; the rear section of the shell is mounted with the coil; the magnetic conductor is arranged in the coil and is moved in the coil by the piston so as to change the inductance of the coil.

2. A piston flux guide position detection device according to claim 1, characterized in that: The measured object is fixed, an air inlet hole is formed in the shell for compressed air to enter the shell and push the piston to move; the driving force for the movement of the piston is the compressed air entering the shell through the air inlet hole; and a sealing ring is arranged between the piston and the shell to ensure air tightness; the piston return spring moves the piston and the testing head to reset in the shell in normal state; the piston moves forward under the action of the compressed air and drives the testing head to move forward until it hits the measured object.

3. A piston flux guide position detection device according to claim 1, characterized in that: The measured object is moving; the driving force for the movement of the piston is the moving measured object; and the piston return spring moves the piston and the testing head to reset at the front end of the shell in normal state; the piston moves backward under the action of the moving measured object.

4. A piston flux guide position detection device according to claim 2 or 3, characterised in that: The front end of the piston is formed with a push rod; the front end of the push rod is directly formed with a flat testing head or a hemispherical testing head; or the front end of the piston is formed with a push rod which is provided with an internal thread; and the testing head is connected to the internal thread.

5. A piston position sensor device according to claim 3, wherein: The front end of the piston is configured with a spherical testing head; the diameter of the front end opening of the shell is smaller than the diameter of the spherical testing head; most of the testing head is limited in the shell, and a small part of the testing head extends out of the front end opening of the shell.

6. A piston flux guide position detection device according to claim 1, 2 or 3, characterised in that: The rear section of the shell is further mounted with a circuit board; and the lead of the coil is connected to the circuit board.

7. A piston position detector device according to claim 6, characterised in that: The front end opening of the shell is in the shape of a neck; and the rear end opening of the shell is in the shape of an open mouth; the rear end of the shell is covered with an insulating wrapping body so as to fix the coil and the circuit board at the rear end of the shell; the insulating wrapping body is formed with a circuit board through hole corresponding to the circuit board; Or, the front end opening of the shell is in the shape of a neck; and the rear end opening of the shell is in the shape of an open mouth; the rear end of the shell is covered with an insulating wrapping body so as to fix the coil and the circuit board at the rear end of the shell; the insulating wrapping body is formed with a circuit board through hole corresponding to the circuit board; and the insulating wrapping body is formed with an air nozzle corresponding to the air inlet hole of the shell.

8. A piston position sensor device according to claim 6, wherein: The circuit board extends out of the side of the shell; or the circuit board extends along the axial direction of the shell.

9. A piston position sensor device according to claim 6, wherein: The rear section of the shell is fixed with a coil support; the rear end of the coil support is fixed with the circuit board; and the coil is mounted on the coil support; or the rear section of the shell is fixed with a coil support; the rear end of the coil support is fixed with the circuit board; the coil is mounted on the coil support; a base is arranged between the coil support and the circuit board; the front side of the base is fixed with the coil support; the rear side of the base is fixed with the circuit board; the base is formed with an extension pipe for the magnetic conductor to extend into corresponding to the center hole of the coil support; the extension pipe is inserted into the center hole of the coil support and abuts against the coil so as to fix the coil; or the rear section of the shell is fixed with a bushing, a tail seat and an insulating sleeve; the coil is fixed in the shell by means of the bushing and the tail seat; and the circuit board is fixed in the shell by means of the insulating sleeve.

10. A piston position sensor device according to claim 6, wherein: The two ends of the coil lead on the circuit board are connected with a capacitor, the capacitor is welded on the circuit board, and the capacitor and the coil form an LC oscillator; alternatively, the two ends of the coil lead are connected with a capacitor, and a tester is also connected; alternatively, the two ends of the coil lead are connected with a tester; alternatively, the circuit board further has a pad connected with the coil lead, and the pad is used for welding an external lead to connect the tester.

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