Linear displacement sensor

Abstract

The utility model discloses a linear displacement sensor, which relates to the technical field of sensors, and comprises a shell, a wire harness, a sheath, a printed circuit board and a sensing element, the printed circuit board is arranged in the shell, a sensing part is arranged on the printed circuit board, one end of the wire harness extends into the shell and is connected with the printed circuit board, and the other end of the wire harness is connected with the sheath. The other end of the wire harness is provided with a sheath, and the lower end of the housing is slidably provided with a sensing element. The induction part comprises a group of exciting coils and two groups of receiving coils, the receiving coils are arranged on the inner sides of the exciting coils, the exciting coils are connected with the oscillating circuit, and the receiving coils are connected with the detection circuit. According to the utility model, the sensing element is connected with the external measured object and is matched with the linear displacement sensor, so that non-contact measurement is realized, stray magnetic fields can be immunized, the interference of disordered magnetic fields is avoided, no magnet is needed, and the cost can be effectively saved.

Description

Technical Field

[0001] This utility model relates to the field of sensor technology, and in particular to a linear displacement sensor. Background Technology

[0002] In the manufacturing process, precise measurement and control of the position and displacement of mechanical components are required to ensure product quality and production efficiency. For example, in automated production lines for automobile manufacturing, the precise position control of robotic arms and the assembly accuracy of parts rely on linear displacement sensors to achieve accurate measurements, ensuring the accuracy and stability of the production process. The function of a linear displacement sensor is to convert the mechanical displacement of an object into an electrical signal. Current technology commonly uses Hall effect sensors to detect the magnitude of the magnetic field by moving the sensor within it, thereby detecting the displacement of the object.

[0003] However, detecting the magnitude of a magnetic field by moving a Hall element in a magnetic field is easily affected by external magnetic fields, which can affect the accuracy of the measurement. It often requires a stable magnetic field source, which increases the production cost of the product. Utility Model Content

[0004] The purpose of this invention is to provide a linear displacement sensor to solve the above-mentioned technical problems.

[0005] The technical solution adopted in this utility model is as follows:

[0006] A linear displacement sensor includes a housing, a wiring harness, a sheath, a printed circuit board, and a sensing element. The printed circuit board is disposed inside the housing and has a sensing portion thereon. One end of the wiring harness extends into the housing and is connected to the printed circuit board, while the other end of the wiring harness is provided with the sheath. The sensing element is slidably disposed at the lower end of the housing.

[0007] The sensing part includes a set of excitation coils and two sets of receiving coils. The receiving coils are located inside the excitation coils. The excitation coils are connected to the oscillation circuit, and the receiving coils are connected to the detection circuit.

[0008] Preferably, the receiving coil comprises an even number of symmetrically distributed polarity coils, with adjacent polarity coils having opposite polarities.

[0009] As a further preferred embodiment, there is a 90° phase difference between two adjacent polar coils, and the two adjacent polar coils alternately form several closed loops along clockwise and counterclockwise winding directions.

[0010] As a further preferred embodiment, several of the closed loops are symmetrically distributed with respect to the center of the receiving coil.

[0011] Preferably, the central axis of the receiving coil coincides with the central axis of the excitation coil.

[0012] Preferably, the excitation coil includes two resistors and a planar coil, the planar coil being connected in parallel with the oscillation circuit through the two resistors, and the planar coil having two output terminals.

[0013] As a further preferred embodiment, it also includes two separate capacitors, with one separate capacitor provided at each of the output terminals.

[0014] Preferably, the sensing element is made of a conductive material.

[0015] The above technical solution has the following advantages or beneficial effects:

[0016] The sensing element in this invention is connected to the external object being measured and works in conjunction with the linear displacement sensor to achieve non-contact measurement. It is immune to stray magnetic fields and avoids interference from chaotic magnetic fields. Furthermore, it eliminates the need for a magnet, effectively saving costs. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the linear displacement sensor in this utility model;

[0018] Figure 2 This is an exploded view of the linear displacement sensor in this utility model;

[0019] Figure 3 This is a schematic diagram of the working principle of the excitation coil and the receiving coil;

[0020] Figure 4 This is a schematic diagram showing the distribution of the excitation coil and the receiving coil;

[0021] Figure 5 This is an exploded schematic diagram of the sensing element in this utility model;

[0022] Figure 6 This is a schematic diagram of the structure of the sheath in this utility model. Figure 1 ;

[0023] Figure 7 This is a schematic diagram of the structure of the sheath in this utility model. Figure 2 ;

[0024] Figure 8 This is a top view of the sheath in this utility model;

[0025] Figure 9 yes Figure 8 Sectional view along the middle AA direction;

[0026] Figure 10 This is an exploded view of the sheath in this utility model;

[0027] Figure 11 This is a schematic diagram of the parallel resonant circuit in this utility model.

[0028] In the diagram: 1. Outer shell; 2. Wiring harness; 3. Sheath; 4. Printed circuit board; 5. Sensing element; 6. Base; 7. Sealing ring; 8. Spring washer; 9. Sealant; 10. Excitation coil; 11. Receiving coil; 12. Polarity coil; 13. Sheath base; 14. Top cover; 15. Sliding rod; 16. Spring; 17. Locking rod; 18. Positioning sleeve; 19. Opening; 20. Positioning groove; 21. Rotating shaft; 22. First sliding hole; 23. Second sliding hole; 24. Limiting hole; 25. Sealing gasket. Detailed Implementation

[0029] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0030] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0032] Please see Figures 1 to 11The diagram illustrates a preferred embodiment of a linear displacement sensor, comprising a housing 1, a wiring harness 2, a sheath 3, a printed circuit board 4, and a sensing element 5. The printed circuit board 4 is disposed inside the housing 1, and a sensing portion is disposed on the printed circuit board 4. One end of the wiring harness 2 extends into the housing 1 and is connected to the printed circuit board 4, while the other end of the wiring harness 2 is covered by the sheath 3. The sensing element 5 is slidably disposed at the lower end of the housing 1. In this embodiment, see [reference needed]. Figure 2 As shown, the sensing element 5 is made entirely of conductive material, which can be a conductive metal such as steel or copper, or a PCB with a copper layer printed on it; the choice depends on the specific requirements. The structure of the sensing element 5 can be found in [reference needed]. Figure 5 As shown, the device includes a metal block and a top cover 14 embedded in the upper part of the metal block. The metal block is connected to the external object being measured. The sensing element 5 is located at the bottom of the outer casing 1 and can slide relative to the outer casing 1. The sensing element 5 is placed on the object being measured to achieve non-contact measurement and avoid interference from stray magnetic fields. The outer casing 1 includes a base 6, a sealing ring 7, a spring washer 8, and sealant 9. The base 6 has a mounting groove, and the sealing ring 7 is placed in the mounting groove for assembly with external accessories to achieve a seal between the accessories and the accessories. A printed circuit board 4 is installed inside the base 6, and sealant 9 is applied to the upper end of the base 6 to seal the printed circuit board 4 inside the base 6. The base 6 has protrusions on both sides, and spring washers 8 are installed in the protrusions.

[0033] In this embodiment, the sheath 3 is used to connect the wire harness 2 to an external wire harness, while ensuring the sealing and safety of the connection point. Existing connection methods involve connecting the wire harness 2 to the external wire harness and then wrapping or filling the connection point with insulating tape. This connection method is not very safe and is inconvenient for later disassembly. In this embodiment, the structure of the sheath 3 can be found in [reference needed]. Figure 6-9As shown, the sheath 3 includes a sheath base 13, a top cover 14, a sliding rod 15, a spring 16, a locking rod 17, and a positioning sleeve 18. A positioning sleeve 18 is provided on the outer edge of one end of the sheath base 13. The interior of the sheath base 13 is hollow, and an opening 19 is provided at the upper end of the sheath base 13. A positioning groove 20 is provided around the opening 19, and the top cover 14 is located within the positioning groove 20. One end of the top cover 14 is rotatably connected to the inner walls of the positioning groove 20 via a pivot 21. The other end of the top cover 14 has several first sliding holes 22 and several second sliding holes 23. The first sliding holes 22 are located above the second sliding holes 23. The interior is hollow, with the first sliding hole 22 and the second sliding hole 23 communicating with the interior of the top cover 14. A sliding rod 15 is located within the first sliding hole 22, and a locking rod 17 is located within the second sliding hole 23. One end of the sliding rod 15 is bent at 90° and connected to one end of the locking rod 17, while the other end extends out of the first sliding hole 22. A limiting hole 24 is formed in the inner wall of the second sliding hole 23. A spring 16 is sleeved around the locking rod 17 and located within the limiting hole 24, with one end of the spring 16 fixedly connected to the locking rod 17 and the other end connected to the inner wall of the limiting hole 24. When the locking rod 17 moves into the top cover 14, the spring 16 is stretched. A positioning hole is formed on the positioning sleeve 18 opposite to the locking rod 17, allowing the locking rod 17 to automatically enter the positioning hole under the action of the spring 16, thereby restricting the position of the top cover 14. In use, pressing the other end of the sliding rod 15 causes the sliding rod 15 to move the locking rod 17 towards the inside of the top cover 14. At this time, the locking rod 17 will stretch the spring 16, and the other end of the locking rod 17 will disengage from the positioning hole, thus losing its restriction on the position of the top cover 14. The top cover 14 can then be rotated to the open position, opening the interior of the protective base 13. When it is necessary to close the top cover 14, first press the sliding rod 15 to move the locking rod 17 towards the inside of the top cover 14, then rotate the top cover 14 so that it enters the positioning groove 20. At this time, the two side walls of the top cover 14 are in close contact with the two side walls of the positioning groove 20, preventing the top cover 14 from shaking and ensuring that the locking rod 17 is aligned with the positioning hole. Then release the sliding rod 15, and the locking rod 17 automatically enters the positioning hole under the action of the spring 16, thus restricting the position of the top cover 14 and keeping the top cover 14 in a closed state. In this embodiment, see... Figure 10As shown, a sealing gasket 25 is provided in the positioning groove 20 to cooperate with the top cover 14 and seal the opening 19. Inlet holes are provided at both ends of the sheath base 13. The wire harness 2 and external wire harnesses can enter the interior of the sheath base 13 through the inlet holes and connect with each other inside the sheath base 13. The connection between the wire harness 2 and the inlet hole can be sealed. For example, the outer sheath of the wire harness 2 can be deformed and inserted into the inlet hole to achieve close contact with the inner wall of the inlet hole, achieving a sealing effect. This seal only needs to prevent water from entering, or a sealing ring can be directly inserted into the inlet hole to achieve a seal between the wire harness 2 and the inner wall of the inlet hole. In this embodiment, a vent hole (not shown in the figure) is provided on the bottom wall of the sheath base 13. A waterproof and breathable membrane can be provided in the vent hole to prevent external water from entering and also to provide a certain heat dissipation effect. In this embodiment, the wire harness 2 can be connected to the external wire harness inside the sheath base 13. Simply open the top cover 14 and then connect the wire harness 2 to the external wire harness. There is no need to wrap the connection with insulating tape or fill it with insulating glue. After the connection, simply close the top cover 14. This can save time and improve work efficiency.

[0034] The sensing section includes one set of excitation coils 10 and two sets of receiving coils 11. The receiving coils 11 are located inside the excitation coils 10. The excitation coils 10 are connected to the oscillation circuit, and the receiving coils 11 are connected to the detection circuit. The linear displacement sensor in this embodiment does not have a magnet and can be used for sensing absolute linear position. The linear displacement sensor is an inductive (electromagnetic coupling) non-contact angle sensor that utilizes the physical principle of eddy currents to detect the position of the sensing element 5. Two sets of receiving coils 11 are provided, each set including two polar coils 12, printed on the printed circuit board 4 in the form of copper traces. In use, the excitation coils 10 generate a changing electromagnetic field. The receiving coils 11 sense the position of the sensing element 5 within this electromagnetic field. The sensing element 5 is made of conductive metal material and generates eddy currents in the changing electromagnetic field, affecting the electromagnetic field of the covered area. The receiving coils 11 convert the change in the electromagnetic field into a change in induced electromotive force, thereby sensing the position of the sensing element 5. The sensing element 5 can be placed above or below the coils, depending on the specific needs.

[0035] Furthermore, in a preferred embodiment, the receiving coil 11 includes an even number of symmetrically distributed polarity coils 12, with adjacent polarity coils 12 having opposite polarities. There is a 90° phase difference between adjacent polarity coils 12, and adjacent polarity coils 12 alternately form several closed loops along clockwise and counterclockwise winding directions, and these closed loops are symmetrically distributed relative to the center of the receiving coil 11. See details... Figure 4As shown, each group of receiving coils 11 includes two polarity coils 12, and one group has four polarity coils 12. Two adjacent polarity coils 12 in each group of receiving coils 11 are wound clockwise and counterclockwise, with their alternating positions (i.e., cross positions) forming a closed loop. The polarities of adjacent polarity coils 12 are opposite, and each segment of induced voltage has alternating opposite polarities. According to Ferrari's law of electromagnetic induction, no induced electromotive force is generated in the uniform alternating magnetic field (or radially symmetrical alternating magnetic field) produced by the excitation coil 10.

[0036] When the central axis of the receiving coil 11 coincides with the central axis of the excitation coil 10, the magnetic flux density amplitude and magnetic field change of each loop in the receiving coil 11 will be consistent. Therefore, the receiving coil 11 does not generate an induced electromotive force in the alternating magnetic field generated by the excitation coil 10. When current is passed through the receiving coil 11, the magnetic flux generated by each pair of loops with opposite polarities will be opposite in direction and cancel each other out, so the total magnetic flux generated is zero. When the induction element 5 is added, eddy currents are generated in the alternating magnetic field of the excitation coil 10. These eddy currents always hinder the alternating magnetic field of the excitation coil 10 from penetrating the induction element 5. In the part covered by the induction element 5, the magnetic field lines perpendicular to the plane of the induction element 5 will be weakened. The magnetic field amplitude of the part covered by the induction element 5 is smaller than that of the part not covered by the induction element 5, resulting in an amplitude step. This causes the receiving coil 11 to have opposite polarities and generate inconsistent magnetic flux, so the induced electromotive forces cannot cancel each other out. As the position of the induction element 5 changes, the induced electromotive force of the receiving coil 11 also changes, and the receiving coil 11 senses the position of the induction element 5.

[0037] Furthermore, as a preferred embodiment, the excitation coil 10 includes two resistors and a planar coil. The planar coil is connected in parallel with the oscillation circuit through the two resistors, and the planar coil has two output terminals. This embodiment also includes two separate capacitors, with one separate capacitor provided at each output terminal. The two resistors R... Tx1 R Tx2 Two separate capacitors C Tx1 C Tx2 Planar coil L Tx The circuit connections between the two resistors, two separate capacitors, the planar coil, and the oscillating circuit can be found in [reference]. Figure 11 As shown, a parallel resonant circuit is formed between two resistors, two separate capacitors, a planar coil, and the oscillating circuit. The oscillating circuit is an LC oscillating circuit.

[0038] The above description is only a preferred embodiment of the present utility model and does not limit the implementation method and protection scope of the present utility model. Those skilled in the art should realize that all solutions obtained by equivalent substitutions and obvious changes made based on the description and illustrations of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A linear displacement sensor, characterized in that, The device includes a housing, a wiring harness, a sheath, a printed circuit board, and a sensing element. The printed circuit board is disposed inside the housing and a sensing part is disposed on the printed circuit board. One end of the wiring harness extends into the housing and is connected to the printed circuit board, and the other end of the wiring harness is disposed on the sheath. The sensing element is slidably disposed at the lower end of the housing. The sensing part includes a set of excitation coils and two sets of receiving coils. The receiving coils are located inside the excitation coils. The excitation coils are connected to the oscillation circuit, and the receiving coils are connected to the detection circuit.

2. The linear displacement sensor as described in claim 1, characterized in that, The receiving coil comprises an even number of symmetrically distributed polarity coils, with adjacent polarity coils having opposite polarities.

3. The linear displacement sensor as described in claim 2, characterized in that, There is a 90° phase difference between two adjacent polar coils, and the two adjacent polar coils alternately form several closed loops along clockwise and counterclockwise winding directions.

4. The linear displacement sensor as described in claim 3, characterized in that, Several of the closed loops are symmetrically distributed with respect to the center of the receiving coil.

5. The linear displacement sensor as described in claim 1, characterized in that, The central axis of the receiving coil coincides with the central axis of the excitation coil.

6. The linear displacement sensor as described in claim 1, characterized in that, The excitation coil includes two resistors and a planar coil. The planar coil is connected in parallel with the oscillation circuit through the two resistors and has two output terminals.

7. The linear displacement sensor as described in claim 6, characterized in that, It also includes two separate capacitors, with one separate capacitor provided at each of the output terminals.

8. The linear displacement sensor as described in claim 1, characterized in that, The sensing element is made of a conductive material.

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