Adjustable Sensitivity Magnetic Bridge Type Permanent Magnet Magnetic Induction Displacement Sensor and Its Adjustment Method

Abstract

This disclosure belongs to the field of measuring instrument technology and provides an adjustable sensitivity magnetic bridge-type permanent magnet magnetic induction displacement sensor and its adjustment method. The displacement sensor includes a sensing component, a detection component, and an adjustment component. The sensing component includes two iron cores and four permanent magnets. The two iron cores are arranged opposite each other and axially aligned. The detection component includes a Hall element disposed between the two opposing iron cores. The four permanent magnets are grouped in pairs and symmetrically disposed at the ends of the two iron cores away from the Hall element. The adjustment component includes at least one armature disposed on one side of the two iron cores, and the distance between the armature and the opposing permanent magnets is adjustable. This disclosure changes the reference magnetic reluctance of the two magnetic flux branches of the magnetic bridge and the static output midpoint of the Hall element by setting an armature with the same material as the measured object or with similar magnetic permeability, and by adjusting the relative distance between the armature and the permanent magnets, thereby changing the reference magnetic reluctance of the two magnetic flux branches of the magnetic bridge and the static output midpoint of the Hall element, thus enabling the displacement sensor to obtain higher sensitivity and better linearity within the target range.

Description

Technical Field

[0001] This disclosure belongs to the field of measuring instrument technology, and in particular relates to an adjustable sensitivity magnetic bridge type permanent magnet magnetic induction displacement sensor and its adjustment method. Background Technology

[0002] In high-humidity, high-dust environments such as dam corridors, traditional CCD, capacitive, and stepper displacement measuring instruments are easily affected by water vapor, mud, dust, and component corrosion, leading to drift, jumps, or even failure of measurement results. In contrast, magnetic flux is not affected by non-ferromagnetic media and is suitable for enclosed, non-contact measurements.

[0003] Existing permanent magnet magnetic induction displacement sensors typically employ a magnetic circuit composed of permanent magnets, iron cores, and Hall elements. Changes in the air gap between the measured ferromagnet and the sensor cause changes in magnetic flux, which are then output as a corresponding voltage by the Hall element. Existing bridge-type schemes utilize four permanent magnets, two iron cores, and one Hall element to form a symmetrical magnetic bridge, making the difference in the reverse magnetic field at the Hall element position correlated with the measured displacement.

[0004] Existing bridge structures still have the following problems in practical applications: 1. After the sensor is assembled, the output midpoint is greatly affected by the magnet installation deviation, magnetic circuit size and target material, which is not conducive to directly obtaining the best sensitivity within the target range.

[0005] 2. The material of the object being measured, the desired measurement range, and the installation space vary in different application scenarios, and the existing fixed structure is difficult to balance the upper limit of measurement, the lower limit of measurement, and linearity.

[0006] 3. Relying solely on circuit zeroing or software compensation will increase the complexity of subsequent processing and cannot directly improve the operating point of the sensor's magnetic circuit.

[0007] Therefore, it is necessary to design a magnetic bridge-type permanent magnet magnetic induction displacement sensor that can adjust the magnetic circuit operating point at the sensor structure level, so as to adjust the sensitivity and output characteristics according to the range requirements without significantly increasing the circuit complexity. Summary of the Invention

[0008] To address the aforementioned issues, this disclosure provides an adjustable sensitivity magnetic bridge-type permanent magnet magnetic induction displacement sensor. By setting an armature with the same material as or similar permeability to the measured object and adjusting the relative distance between the armature and the permanent magnet, the reference magnetic reluctance of the two magnetic flux branches of the magnetic bridge and the static output midpoint of the Hall element are changed, thereby enabling the displacement sensor to achieve higher sensitivity and better linearity within the target range.

[0009] In a first aspect, this disclosure provides an adjustable sensitivity magnetic bridge-type permanent magnet magnetic induction displacement sensor, comprising: a sensing component, a detection component, and an adjustment component; the sensing component includes two iron cores and four permanent magnets; the two iron cores are arranged opposite each other and axially aligned; the detection component includes a Hall element disposed between the two opposing iron cores; the four permanent magnets are grouped in pairs and symmetrically disposed at the ends of the two iron cores away from the Hall element; the adjustment component includes at least one armature disposed on one side of the two iron cores, and the distance between the armature and the opposing permanent magnets is adjustable. Furthermore, The two iron cores have the same shape and material properties.

[0010] Furthermore, In each group, two permanent magnets are positioned on the upper and lower sides of the corresponding iron core end.

[0011] Furthermore, In the same group, the two permanent magnets face opposite polarities toward the iron core, while in different groups, the permanent magnets located on the same side of the iron core face opposite polarities.

[0012] Furthermore, Four permanent magnets, two iron cores, and a Hall element form a symmetrical magnetic bridge.

[0013] Furthermore, When there is no object being measured or the object being measured is a non-ferromagnetic material, the total magnetic flux at the location of the Hall element is close to zero.

[0014] The armature is made of the same material as the object being tested or has a similar magnetic permeability.

[0015] Furthermore, The armature has a regular shape and is set parallel to the iron core.

[0016] Secondly, based on the same inventive concept, this disclosure also provides a method for adjusting the measurement accuracy of a magnetic bridge-type permanent magnet magnetic induction displacement sensor. Based on the magnetic bridge-type permanent magnet magnetic induction displacement sensor described in the foregoing embodiments: the armature material and size are selected according to the target range and the material of the object being measured; the reference gap between the armature and the permanent magnet is adjusted, and the output voltage signal of the Hall element at several positions of the armature is collected; based on the collected voltage signal, the reference gap is determined with the goal of maximizing sensitivity, minimizing linear error, or ensuring the output midpoint falls within a preset range within the target range; and the armature position is fixed according to the reference gap.

[0017] Furthermore, The armature serves as an adjustment component for the reference gap, used to preset the static balance point of the magnetic bridge of the sensor.

[0018] Compared with the prior art, this disclosure provides a magnetic bridge type permanent magnet magnetic induction displacement sensor with adjustable sensitivity, which has the following advantages: 1. By introducing a reference armature into the displacement sensor body, the static output midpoint can be adjusted directly from the magnetic circuit level, rather than relying solely on subsequent electronic compensation.

[0019] 2. The armature material is the same as or has a similar magnetic permeability to the material being measured, so that the magnetic characteristics of the reference branch are more closely matched with the actual object being measured, and the adjustment results are more targeted.

[0020] 3. By adjusting the distance between the armature and the permanent magnet, the position of the midpoint of the static output of the Hall element can be changed, so that the displacement sensor can achieve or approach the optimal sensitivity operating point under different range requirements.

[0021] 4. For the same magnetic bridge foundation structure, different ranges can be adapted by changing the position of the reference armature, reducing the need to redesign the entire magnetic circuit structure.

[0022] 5. With the optimization of the bridge arm span and permanent magnet size, the linearity and resolution of the displacement sensor can be further improved while ensuring the advantages of non-contact and fully enclosed measurement.

[0023] 6. Suitable for displacement measurement scenarios in high humidity and high dust environments, such as displacement monitoring of dam plumb lines, tension lines, and other ferromagnetic targets.

[0024] Other features and advantages of this disclosure will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the disclosure. The objects and other advantages of this disclosure may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 A schematic diagram illustrating the structural principle of an adjustable sensitivity magnetic bridge type permanent magnet magnetic induction displacement sensor according to an embodiment of the present disclosure is shown. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0028] Figure 1 A schematic diagram illustrating the structural principle of an adjustable sensitivity magnetic bridge type permanent magnet magnetic induction displacement sensor according to an embodiment of the present disclosure is shown.

[0029] like Figure 1 As shown in the figure, an adjustable sensitivity magnetic bridge type permanent magnet magnetic induction displacement sensor according to an embodiment of the present disclosure includes: a sensing component, a detection component, and an adjustment component.

[0030] The sensing component includes two iron cores (iron core 1 and iron core 2) and four permanent magnets (permanent magnet 1A, permanent magnet 2B, permanent magnet 3C and permanent magnet 4D).

[0031] The two iron cores are arranged opposite each other and aligned axially. Preferably, the two iron cores have the same shape and material properties; and their cross-sections are of regular geometric shapes.

[0032] The detection assembly includes a Hall element 3, which is disposed between two opposing iron cores.

[0033] The four permanent magnets are grouped in pairs (groups AB and CD) and symmetrically arranged at the ends of the two iron cores furthest from the Hall element. In each group, two permanent magnets are located on the upper and lower sides of the corresponding iron core ends.

[0034] In this arrangement, the two permanent magnets in the same group have opposite polarities facing the iron core (A and B are opposite, C and D are opposite), while the permanent magnets in different groups located on the same side of the iron core have opposite polarities (A and C are opposite, B and D are opposite). This arrangement is to create two sets of magnetic fields with opposite directions at Hall element 3. Figure 1 As shown by the closed lines with arrows, the Hall element 3 is positioned vertically and horizontally. The two iron cores serve to conduct and confine the magnetic field.

[0035] The adjustment assembly includes at least one armature 4. The armature 4 is disposed on one side of the two iron cores, and the distance between it and the opposing permanent magnet is adjustable. The material of the armature is the same as or has a similar magnetic permeability to the object being tested 5.

[0036] As a preferred method, the armature 4 and the object being tested are located on different sides of the iron core; the armature 4 has a regular shape, such as a cuboid, and the armature is arranged parallel to the iron core.

[0037] The working principle of the adjustable sensitivity magnetic bridge type permanent magnet magnetic induction displacement sensor in this embodiment is described as follows: Four permanent magnets and two iron cores (including Hall elements) form a symmetrical magnetic bridge. When there is no object being measured (or the object being measured is a non-ferromagnetic material), the total magnetic flux at the location of Hall element 3 is zero or close to zero. In this state, the output voltage (induced voltage) of Hall element 3 is defined as being at the "static output midpoint." When the ferromagnetic object being measured 5 approaches one of the permanent magnets ( Figure 1 When A and C are in the middle, the magnetic reluctance of the magnetic circuit on that side decreases ( Figure 1 (The magnetic permeability of the test object 5 is greater than that of air). The Hall element 3 detects the change in the differential magnetic field (compared to the magnetic field in the air when there is no test object 5), and thus outputs a voltage signal that deviates from the midpoint of the static output.

[0038] The magnitude of the voltage signal deviation from the static output midpoint is related to the distance between the object under test (DUT) and the sensor (permanent magnet). In specific applications, when the DUT moves relative to the sensor, the Hall element's output voltage will deviate from the static output midpoint. Based on the mathematical relationship between the voltage deviation difference and the moving distance, the distance the DUT has moved relative to the sensor can be calculated.

[0039] As a significant technological innovation, the embodiments of this disclosure introduce an armature 4 as an adjusting element for the reference gap, used to preset the static balance point of the magnetic bridge (corresponding to the aforementioned "static output midpoint"). See appendix. Figure 1 By adjusting the armature 4 and the relative permanent magnet ( Figure 1 Reference gap between B and D) l r The magnetic reluctance of the reference branch can be changed. Figure 1 The upper middle magnetic field enters the armature 4, thereby changing the output voltage of the Hall element 3 under the same displacement. The change in the midpoint of the static output will change the aforementioned "mathematical relationship between the voltage deviation difference and the distance the measured object moves," such as the rate of change of the distance the measured object moves relative to the voltage difference (i.e., the unit rate of change), thereby changing the sensitivity of the sensor and improving the measurement resolution and linearity within the target range. Therefore, in this embodiment, the armature 4 is a component for adjusting the sensitivity of the displacement sensor.

[0040] In one specific embodiment, the armature 4 is disposed at... Figure 1 The outer side of the upper middle permanent magnet, with the distance between the armature and the nearest permanent magnet surface serving as the reference gap. l r The distance between the object being measured and the permanent magnet facing the object is the distance to be measured. l .

[0041] The air gap magnetic reluctance of the magnetic flux branch from the sensor to the object being measured can be expressed as: Ra = l / ( μ a • S arm ), in: l The distance to be measured is the distance between the object being measured and the sensor. μ a air permeability; S arm It is the equivalent cross-sectional area of ​​the air gap magnetic flux branch corresponding to the object being measured.

[0042] The air gap reluctance of the reference flux branch on the armature side can be expressed as: R r = l r / ( μ a • S r ), in: l r This is the reference gap between the armature and the corresponding permanent magnet; S r The equivalent cross-sectional area of ​​the reference air gap flux branch.

[0043] From the above relationship, it can be seen that when the magnetic induction intensity at the Hall element... B hall When the difference in main magnetic flux between the upper and lower sides of the magnetic bridge is determined, adjust... l r Essentially, it involves adjusting the magnetic reluctance of the reference branch. R r This causes a change in the local slope of the static output midpoint and its shift curve of the Hall element. Within the target range... B hall and( l + C ) -1 There is a proportional relationship; by choosing the appropriate... l r This can increase the magnetic flux density at the Hall element. B hall Distance to be measured l The correspondence is closer to linear within the working interval. Among them, the constant... C It is related to parameters such as the size of the magnetic bridge, the parameters of the permanent magnet, the armature material, and the reference gap of the armature size.

[0044] Based on the same inventive concept, this invention proposes a method for adjusting the measurement accuracy of a magnetic bridge-type permanent magnet magnetic induction displacement sensor. Based on the magnetic bridge-type permanent magnet magnetic induction displacement sensor described in the foregoing embodiments: the armature material and size are selected according to the target range and the material of the object being measured; the reference gap between the armature and the permanent magnet is adjusted, and the output voltage signals of the Hall element at several positions of the armature (i.e., different reference gaps) are collected; based on the collected voltage signals, the reference gap is determined with the goal of maximizing sensitivity within the target range, minimizing linear error, or ensuring the output midpoint falls within a preset range; the armature position is fixed according to the reference gap.

[0045] The key to this embodiment is the introduction of an armature in the magnetic bridge type permanent magnet magnetic induction displacement sensor that is the same as or has a similar magnetic permeability to the material being measured. The static output midpoint and sensitivity of the Hall element are set by adjusting the relative distance between the armature and the permanent magnet, so that the sensor can perform structural-level measurement accuracy matching around the target range.

[0046] Although the present disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A magnetic bridge-type permanent magnet magnetic induction displacement sensor with adjustable sensitivity, characterized in that, include: Sensing components, detection components, and adjustment components; The sensing assembly includes two iron cores and four permanent magnets; the two iron cores are arranged opposite each other and axially aligned. The detection assembly includes a Hall element disposed between two opposing iron cores; The four permanent magnets are grouped in pairs and symmetrically arranged at the ends of the two iron cores away from the Hall element; The adjustment assembly includes at least one armature, which is disposed on one side of the two iron cores and the spacing between it and the opposing permanent magnet is adjustable.

2. The adjustable sensitivity magnetic bridge type permanent magnet magnetic induction displacement sensor according to claim 1, characterized in that, The two iron cores have the same shape and material properties.

3. The adjustable sensitivity magnetic bridge type permanent magnet magnetic induction displacement sensor according to claim 1, characterized in that, In each group, two permanent magnets are positioned on the upper and lower sides of the corresponding iron core end.

4. The adjustable sensitivity magnetic bridge type permanent magnet magnetic induction displacement sensor according to claim 3, characterized in that, In the same group, the two permanent magnets face opposite polarities toward the iron core, while in different groups, the permanent magnets located on the same side of the iron core face opposite polarities.

5. The adjustable sensitivity magnetic bridge type permanent magnet magnetic induction displacement sensor according to any one of claims 1-4, characterized in that, The armature is made of the same material as the object being tested or has a similar magnetic permeability.

6. The adjustable sensitivity magnetic bridge type permanent magnet magnetic induction displacement sensor according to claim 5, characterized in that, The armature is set parallel to the iron core.

7. The adjustable sensitivity magnetic bridge type permanent magnet magnetic induction displacement sensor according to claim 1, characterized in that, Four permanent magnets, two iron cores, and a Hall element form a symmetrical magnetic bridge.

8. The adjustable sensitivity magnetic bridge type permanent magnet magnetic induction displacement sensor according to claim 1, characterized in that, When there is no object being measured or the object being measured is a non-ferromagnetic material, the total magnetic flux at the location of the Hall element is close to zero.

9. A method for adjusting the measurement accuracy of a magnetic bridge type permanent magnet magnetic induction displacement sensor, based on the magnetic bridge type permanent magnet magnetic induction displacement sensor according to any one of claims 1-8, characterized in that: Select the armature material and size according to the target range and the material of the object being measured; Adjust the reference gap between the armature and the permanent magnet, and collect the output voltage signal of the Hall element at several positions of the armature; Based on the acquired voltage signal, the reference gap is determined with the goal of maximizing sensitivity, minimizing linear error, or ensuring the output midpoint falls within a preset range within the target range. The armature position is fixed according to the reference gap.

10. The method for adjusting the measurement accuracy of the magnetic bridge type permanent magnet magnetic induction displacement sensor according to claim 9, characterized in that, The armature serves as an adjustment component for the reference gap, used to preset the static balance point of the magnetic bridge of the sensor.

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