Displacement sensor

Abstract

The utility model discloses a displacement sensor which comprises an inductive head, a circuit board, a main coil and a secondary coil are arranged in the inductive head, the main coil and the secondary coil are arranged on the circuit board, the secondary coil is located in the main coil, and when current is supplied to the main coil or the secondary coil, mutual induction electromotive force can be generated between the main coil and the secondary coil; the target element is a metal part or a non-metal conductor; and the inductive head is fixed, so that the target element moves on one side of the inductive head, and the mutual induction electromotive force between the main coil and the secondary coil can change along with the position change of the target element. The beneficial effects are that the target element moves on one side of the inductive head, and displacement conversion can be carried out through a mutual inductance electric change rule between the primary coil and the secondary coil, so that the displacement of the target element is obtained, and displacement measurement of a target product is realized.

Description

Technical Field

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

[0002] A displacement sensor is a device used to measure and record the distance moved by a moving part. Its working principle is mainly based on converting mechanical displacement into electrical signals or other forms of information output to meet the requirements of information transmission, processing, storage, display, recording and control.

[0003] Based on different measurement principles, current displacement sensors mainly include resistive displacement sensors, inductive displacement sensors, capacitive displacement sensors, photoelectric displacement sensors, and ultrasonic displacement sensors. With the continuous development of industrial automation, different fields are placing increasingly stringent requirements on the accuracy and precision of displacement sensor measurements. However, sensors based on existing measurement principles are almost all nearing their developmental limits, making significant technological breakthroughs difficult to achieve.

[0004] To address this, the applicant has taken a different technical approach and developed a novel displacement sensor based on the principle of multi-coil mutual inductance electromotive force change. Utility Model Content

[0005] In view of this, the present invention provides a displacement sensor that measures displacement by influencing the mutual inductance between coils by a target element, thereby providing a displacement sensor with higher measurement accuracy.

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

[0007] A displacement sensor, the key feature of which is that it includes:

[0008] The induction head contains a circuit board and a main coil and a secondary coil arranged on the circuit board. The secondary coil is located inside the main coil. When current is applied to the main coil or the secondary coil, a mutual induced electromotive force can be generated between the main coil and the secondary coil.

[0009] The target element is either a metallic component or a non-metallic conductor.

[0010] The sensing head is fixed, and the target element is moved to one side of the sensing head. The mutual inductance electromotive force between the main coil and the secondary coil can change with the position of the target element.

[0011] Preferably, the main coil is a rectangular coil and the secondary coil is a sine coil.

[0012] Preferably, there are multiple secondary coils, and each of the secondary coils is arranged sequentially within the main coil with a 90° phase difference.

[0013] Preferably, the induction head has several sets of main coils arranged inside, with adjacent sets of main coils connected end to end, and each set of main coils has a secondary coil.

[0014] Preferably, two adjacent main coils are staggered at their head-to-tail junctions, and there is an overlap at the head-to-tail junctions. The coverage width of the target element is greater than the sum of the widths of the two adjacent main coils.

[0015] Preferably, two adjacent main coils are separately arranged on two circuit boards, with the main coils on the two circuit boards arranged face to face and parallel to each other, and a channel is formed between the two circuit boards for the target component to move back and forth.

[0016] Preferably, two adjacent main coils are separately arranged on two circuit boards, with the planes containing the main coils on the two circuit boards arranged at an angle, and the target element has two covering surfaces that are parallel to both circuit boards at the same time.

[0017] Preferably, two adjacent main coils are provided with induction markers at their joints.

[0018] Preferably, the target element is a metal block.

[0019] Preferably, the width of the target element is less than or equal to one-quarter the length of a single sine coil.

[0020] Preferably, the primary coil contains three or four secondary coils.

[0021] Compared with the prior art, the beneficial effects of this utility model are:

[0022] 1. Using the displacement sensor provided by this utility model, the target element moves on one side of the sensing head. The displacement can be calculated by the mutual inductance electric change law between the primary and secondary coils, thereby obtaining the displacement of the target element and realizing the displacement measurement of the target product. This provides a new displacement sensing measurement method with extremely excellent measurement accuracy.

[0023] 2. Excellent resistance to magnetic field interference: High-frequency excitation current can be passed through the induction coil of the displacement sensor, while external electromagnetic interference is generally low-frequency electromagnetic field, effectively resisting magnetic field interference. It is particularly suitable for various motors and medical MRI fields. The measurement between the sensing head and the target element can be non-contact, enabling the device to operate without wear and tear for extended periods, requiring no maintenance. Attached Figure Description

[0024] Figure 1 This is a schematic diagram illustrating the principle of the displacement sensor of this utility model.

[0025] Figure 2 This is a schematic diagram showing the arrangement of multiple coil units connected end to end.

[0026] Figure 3 The graph shows the displacement-output curve of the induced electromotive force of the secondary coil (sine coil) as a function of the displacement of the target metal block.

[0027] Figure 4 A comparison graph showing the displacement-output curve of the induced electromotive force of the secondary coil (cosine coil) as a function of the displacement of the target metal block.

[0028] Figure 5 This is a comparison graph showing the displacement-output curves of the induced electromotive force of multiple sinusoidal coils arranged with a 90° phase difference as the target metal block is displaced.

[0029] Figure 6 This is a schematic diagram showing two adjacent coils staggered at their beginning and end.

[0030] Figure 7 This is a schematic diagram showing two adjacent sets of coils arranged with their ends flush together.

[0031] Figure 8 This is a schematic diagram showing two adjacent main coils arranged face-to-face and parallel in space.

[0032] Figure 9 This is a schematic diagram showing two adjacent main coils arranged at an angle in space.

[0033] Figure 10 A schematic diagram showing the placement of induction marker 5 at the junction of two adjacent main coils.

[0034] Figure 11 This is a schematic diagram of an installation where the main coils are printed on a PCB and arranged face-to-face in space. Detailed Implementation

[0035] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0036] like Figure 1 As shown, a displacement sensor mainly comprises a sensing head 1 and a target element 2. The sensing head 1 contains a circuit board on which a main coil 3 and a secondary coil 4 are arranged. The secondary coil 4 is located within the main coil 3. When current is applied to either the main coil 3 or the secondary coil 4, a mutual induced electromotive force is generated between them. The target element 2 is a metal component or a non-metallic conductor. In this embodiment, the target element 2 is preferably a metal block.

[0037] After the sensing head 1 and target element 2 are applied to the device under test, the sensing head 1 is fixed, while the target element 2 can move back and forth within a short distance in a plane parallel to the plane of the main coil 3 on one side of the sensing head 1. When there is an alternating current in the main coil 3, a uniform alternating electromagnetic field is distributed inside the main coil 3, thus inducing an electromotive force in the secondary coil 4. At this time, the target element 2, which is metal or has conductive properties, is parallel to and close to the coil. The target element 2 will generate eddy currents that resist the alternating electromagnetic field nearby, causing a shielding effect on the part of the secondary coil 4 covered by the target element 2, and its induced electromotive force will be greatly attenuated. Based on this, by moving the target element 2 on one side of the sensing head 1, the displacement of the target element 2 can be obtained by calculating the displacement of the mutual inductance electromotive force between the main and secondary coils, thereby realizing the displacement measurement of the target product.

[0038] For example Figure 1 As shown, in this embodiment, the main coil 3 is a rectangular coil, and the secondary coil 4 is a sine coil. To achieve absolute value measurement, each main coil 3 contains at least two sine coils, and the sine coils are arranged sequentially within the main coil 3 with a 90° phase difference.

[0039] The principle of absolute displacement measurement using two sinusoidal coils is as follows:

[0040] Please refer to Figure 3Divide the secondary coil 4 of the sinusoidal waveform into four equal parts (A, B, C, and D) according to phase. Each part represents a 90-degree phase. The output of the secondary coil 4 is the superposition of A, B, C, and D. Since the coil is wound symmetrically in both directions, the superposition effect is zero, and the output is zero. After the target element 2 covers one side of the main coil 3, its width exactly covers 1 / 4 of the secondary coil, which is the width occupied by the 90-degree phase. When alternating current flows through the main coil, an induced electromotive force (EMF) is generated in the secondary coil. Since the target element 2 is metal and conductive, the portion of the secondary coil 4 covered by the metal experiences a shielding effect, significantly attenuating its induced EMF. The result is that the output of the sinusoidal coil is the superposition of parts B, C, and D. Because B and C are opposite in direction and symmetrical, the output is the induced EMF of part D. Similarly, when target element 2 completely covers B, the output is the induced EMF of part C; when it completely covers C, the output is the induced EMF of part B; and when it completely covers D, the output is the induced EMF of part A. From this pattern, we can see that whichever part target element 2 covers, the symmetrical reverse output of the other part is obtained. When target element 2 moves to the position between A and B, i.e., the 45-degree phase point, its covered area reaches its maximum, thus the reverse output is also at its highest, i.e., the output reaches its lowest point L, which is the low point L on the displacement-output curve. Target element 2 is shifted 90 degrees to the right to obtain output point Z (0). Target element 2 is then shifted another 90 degrees to the right to obtain high point H. By subdividing the shift values, the output can be obtained. Figure 3 The lower half of the displacement-output curve shows a change in area corresponding to the target element 2, but with the opposite sign. This displacement-output curve is also sinusoidal, but its phase differs from the secondary coil pattern by 90 degrees. For example... Figure 4 Shifting the aforementioned sine coil by 90 degrees is equivalent to arranging a cosine secondary coil. Similarly, we can also obtain... Figure 4 The displacement-output curve of the lower half of the cosine coil.

[0041] Based on the above physical principles, through the multilayer printing process of PCBs, two secondary coils, one sinusoidal and one cosine-shaped, can be superimposed onto the same primary coil. Please refer to... Figure 5That is, two sinusoidal coils are arranged within a single main coil 3, with a 90° phase difference between them. The output of the sinusoidal coil is expressed as SIN, and the output of the cosine coil as COS. Then: if COS > 0 and COS > SIN, the target element 2 is mostly located in region A. If COS = 0 and COS > SIN, the target element 2 is exactly located in the middle of region AB. If COS < 0 and COS > SIN, the target element 2 is mostly located in region B. If COS < 0 and COS = SIN, the target element 2 completely covers region B. Other cases follow the same logic and will not be elaborated further. Therefore, during the movement of the target element 2 from left to right, accurate real-time positioning can be obtained through the SIN and COS values. In practical use, the SIN and COS values ​​are calculated using a microcontroller. Since TAN = SIN / COS, the displacement value can be calculated using the arc(TAN) function table.

[0042] Therefore, for better measurement, the width of target element 2 is preferably equal to one-quarter the length of a single sine coil. In practical applications, through subdivision techniques, target element 2 can be smaller than 1 / 4 of the coil area, resulting in more practical sensor examples.

[0043] The single main coil 3 contains multiple secondary coils 4, which is an absolute displacement measurement technology. Therefore, multiple coil units can be connected end-to-end, and the data from each coil unit can be linked to extend the travel range. Please refer to [link / reference needed] for details. Figure 2 One approach is to arrange several sets of main coils 3 sequentially along the length of the sensing head 1, with adjacent sets of main coils 3 connected end-to-end. Each set of main coils 3 contains multiple secondary coils 4. To prevent electromagnetic interference between the coils, adjacent main coils 3 are staggered, resulting in an overall layout of two alternating rows.

[0044] This embodiment also provides four specific arrangements of multiple main coils 2, as follows:

[0045] like Figure 6 As shown, two adjacent main coils 3 are staggered at their head-to-tail junctions, with overlapping portions at the junctions. The coverage width of the target element 2 is greater than the sum of the widths of the two adjacent main coils 3. In this scheme, the target element 2 is a metal block that moves from left to right. At any position, the metal block can simultaneously cover the necessary sensing area for each set of induction coils. At the junctions, the data source is determined by comparing the sensing intensity (i.e., coverage area) of the induction coils with that of the metal block. Finally, the travel data is spliced ​​together and integrated for output.

[0046] like Figure 7As shown, two adjacent sets of main coils 3 are connected end to end, and the target element 2 is a metal block. At the junction, the data source is determined by comparing the induction intensity (i.e., coverage area) of the metal block with the induction coil. Finally, the travel data is spliced ​​together and integrated for output.

[0047] like Figure 8 As shown, two adjacent main coils 3 are separately arranged on two circuit boards. The main coils 3 on the two circuit boards are arranged face-to-face and parallel, and a channel is formed between the two circuit boards for the target element 2 to move back and forth. When the target element 2 moves through the channel, it can be sensed at corresponding positions on both sides. In this scheme, the two adjacent main coils 3 can be exactly connected end to end, or they can overlap and intersect. See attached diagram. Figure 11 As shown, this embodiment can be implemented by mounting the sensor using a profile 5. The profile 5 has two opposing mounting slots 6 inside, and a sliding channel 7 is formed between the two mounting slots 6. The main coil 3 is printed on the PCB board, the PCB board is fixed in the mounting slots 6, and the target component 2 is slidably set in the sliding channel 7.

[0048] like Figure 9 As shown, two adjacent main coils 3 are separately arranged on two circuit boards at an angle, meaning the planes containing the two adjacent main coils 3 are arranged at an angle. The target element 2 has two covering surfaces that can simultaneously be parallel to both circuit boards. The target element 2 is a metal block that slides along the length of the angle between the coils and circuit boards. The angle between the two circuit boards can be 30°, 45°, 60°, or 90°. In this design, the two adjacent main coils 3 can be joined end-to-end or overlapped.

[0049] The above-mentioned spatial connection schemes are not limited to straight lines and can be applied to curved surfaces and circles. As long as multiple coil substrates and a single metal block are used in combination, and the multiple coil substrates are fixed in relationship during operation, and they move relative to the metal block together, and the combination uses a scheme of head-to-tail collision, misaligned connection, opposite side connection, or angled connection, it falls within the protection scope of this scheme.

[0050] For further details, please refer to Figure 10 In all connection schemes, a sensing mark 5 can be set at the junction of two adjacent main coils 3. Its function is to accurately separate data or improve reliability. The sensing mark 5 can be in the form of a magnet, a reflective surface, or a metal sensing point, to provide additional signals to enable the sensing circuit to detect the junction.

[0051] Finally, it should be noted that the above description is merely a preferred embodiment of the present utility model. Those skilled in the art, under the guidance of the present utility model, can make various similar representations without departing from the spirit and claims of the present utility model, and such modifications all fall within the protection scope of the present utility model.

Claims

1. A displacement sensor, characterized in that, include: The induction head (1) is provided with a circuit board and a main coil (3) and a secondary coil (4) arranged on the circuit board. The secondary coil (4) is located inside the main coil (3). When current is passed through the main coil (3), a mutual inductance electromotive force can be generated between the main coil (3) and the secondary coil (4). as well as The target element (2) is a metal component or a non-metallic conductor; The sensing head (1) is fixed, and the target element (2) is moved to one side of the sensing head (1). The mutual inductance electromotive force between the main coil (3) and the secondary coil (4) can change with the position of the target element (2).

2. The displacement sensor according to claim 1, characterized in that: The main coil (3) is a rectangular coil, and the secondary coil (4) is a sine coil.

3. The displacement sensor according to claim 2, characterized in that: There are multiple secondary coils (4), and each of the secondary coils (4) is arranged sequentially within the main coil (3) with a 90° phase difference.

4. The displacement sensor according to claim 1, characterized in that: The sensing head (1) has several sets of main coils (3) arranged inside, with two adjacent sets of main coils (3) connected end to end, and each set of main coils (3) has a secondary coil (4).

5. The displacement sensor according to claim 4, characterized in that: The two adjacent main coils (3) are staggered at the junction of their ends, and there is an overlap at the junction of their ends. The coverage width of the target element (2) is greater than the sum of the widths of the two adjacent main coils (3).

6. The displacement sensor according to claim 4, characterized in that: The two adjacent main coils (3) are separately arranged on two circuit boards. The main coils (3) on the two circuit boards are arranged face to face and parallel to each other, and a channel is formed between the two circuit boards for the target element (2) to move back and forth.

7. The displacement sensor according to claim 4, characterized in that: The two adjacent main coils (3) are separately arranged on two circuit boards, and the planes on the two circuit boards where the main coils (3) are located are arranged at an angle. The target element (2) has two covering surfaces that are parallel to the two circuit boards at the same time.

8. The displacement sensor according to claim 4, characterized in that: The two adjacent main coils (3) are provided with induction markers (5) at the joint.

9. The displacement sensor according to claim 1, characterized in that: The target element (2) is a metal block.

10. The displacement sensor according to claim 2, characterized in that: The width of the target element (2) is less than or equal to one-quarter the length of a single sine coil.

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