CN216115842U - Differential eddy current displacement detector - Google Patents
Differential eddy current displacement detector Download PDFInfo
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- CN216115842U CN216115842U CN202121865425.0U CN202121865425U CN216115842U CN 216115842 U CN216115842 U CN 216115842U CN 202121865425 U CN202121865425 U CN 202121865425U CN 216115842 U CN216115842 U CN 216115842U
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- eddy current
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- current probe
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Abstract
The utility model discloses a differential eddy current displacement detection device, which comprises a high-frequency sine generator, a first differential eddy current probe, a second differential eddy current probe, a differential pre-detector and a post-amplifier, wherein the high-frequency sine generator, the first differential eddy current probe and the second differential eddy current probe are connected with the differential pre-detector; the first differential eddy current probe and the second differential eddy current probe have the same structure and respectively comprise an inductor and a resistor which are connected in series; the high-frequency sine generator sends the produced sine wave signal with fixed frequency to the first differential eddy current probe and the second differential eddy current probe to generate differential eddy current signals, and the differential eddy current signals are detected by the differential pre-detector, filtered and sent to the post-amplifier for amplification. The utility model can inhibit temperature drift and improve the displacement detection precision of the device.
Description
Technical Field
The utility model belongs to the technical field of displacement detection, and particularly relates to a differential eddy current displacement detection device.
Background
The eddy current displacement sensor is a non-contact micro-displacement sensor, has the characteristics of non-contact, high linearity and high resolution, and is commonly used for measuring the dynamic displacement of a rotating shaft of a high-speed rotating machine. The eddy current displacement sensor detects micro displacement by using the principle of eddy current effect, and when an excitation source applies high-frequency alternating current to a probe coil, the coil can generate an alternating magnetic field and an induction electric field. When a metal conductor is close to the coil, the induced electric field can generate induced eddy current on the surface of the metal conductor. The electrical eddy currents produce an eddy current magnetic field that is opposite in direction to the coil magnetic field and cancels a portion of the coil magnetic field, thereby causing the impedance of the coil to change. When the distance between the metal conductor and the coil changes, the impedance of the coil changes along with the change, so that the distance between the metal conductor and the coil is measured according to the impedance. The current eddy current displacement sensor has the advantages, but the accuracy and stability of displacement measurement in actual use are easily influenced by temperature drift, probe manufacturing accuracy and workpiece mounting process accuracy.
SUMMERY OF THE UTILITY MODEL
The utility model mainly aims to overcome the defects of the prior art and provide a differential eddy current displacement detection device, which combines a differential signal with an eddy current sensor and solves the problems of easy influence of temperature drift and low measurement precision during workpiece displacement detection.
In order to achieve the purpose, the utility model adopts the following technical scheme:
the utility model provides a differential eddy current displacement detection device, which comprises a high-frequency sine generator, a first differential eddy current probe, a second differential eddy current probe, a differential pre-detector and a post-amplifier, wherein the high-frequency sine generator, the first differential eddy current probe and the second differential eddy current probe are connected with the differential pre-detector, and the differential pre-detector is connected with the post-amplifier; the first differential eddy current probe and the second differential eddy current probe have the same structure and respectively comprise an inductor and a resistor which are connected in series; the high-frequency sine generator sends the produced sine wave signal with fixed frequency to the first differential eddy current probe and the second differential eddy current probe to generate differential eddy current signals, and the differential eddy current signals are detected by the differential pre-detector, filtered and sent to the post-amplifier for amplification.
Preferably, the first differential eddy current probe and the second differential eddy current probe are arranged oppositely.
As a preferred technical scheme, the high-frequency sine generator comprises a crystal oscillator, a first operational amplifier circuit and a second operational amplifier circuit, wherein the crystal oscillator generates a square wave signal with a fixed frequency, and then the square wave signal is filtered by the first operational amplifier circuit and the second operational amplifier circuit in sequence to generate a high-frequency sine signal.
As a preferred technical solution, the crystal oscillator is an active crystal oscillator.
Preferably, the first operational amplifier circuit and the second operational amplifier circuit both employ AD817 operational amplifiers.
Preferably, the differential pre-detector comprises a differential amplifier U3 and a fourth operational amplifier U4, the first differential eddy current probe and the second differential eddy current probe are respectively connected in parallel with a capacitor to form a bridge circuit and are connected to a third operational amplifier U3, and the third operational amplifier U3 is connected to a fourth operational amplifier U4.
As a preferable technical solution, the third operational amplifier U3 is INA 103; the fourth operational amplifier U4 is AD 835.
Preferably, the post-amplifier comprises a fifth operational amplifier U5 and a sixth operational amplifier U6, and an output terminal of the fifth operational amplifier U5 is connected to an input terminal of the sixth operational amplifier U6.
Preferably, the fifth operational amplifier U5 is OPA 192.
Preferably, the sixth operational amplifier is AD 8421.
Compared with the prior art, the utility model has the following advantages and beneficial effects:
the utility model provides a differential eddy current displacement detection device, which detects the relative displacement of a workpiece in the device by combining a differential signal and an eddy current sensor; the device uses two sets of coil probes in the same winding mode, and because the two sets of probes are at the same environmental temperature in the device, the adverse effect of temperature drift can be effectively inhibited; meanwhile, since the relative displacement is found out using the differential signal instead of the absolute displacement, the influence of the manufacturing accuracy on the measurement can be reduced.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the utility model, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the utility model and together with the description serve to explain the utility model and not to limit the utility model. In the drawings:
FIG. 1 is a block diagram of a differential eddy current displacement sensing apparatus according to the present invention;
FIG. 2 is a schematic diagram of the connection of a first differential eddy current probe and a second differential eddy current probe of the present invention;
FIG. 3 is a schematic circuit diagram of the high frequency sine generator of the present invention;
FIG. 4 is a circuit schematic of the differential pre-detector of the present invention;
fig. 5 is a circuit schematic of the post-amplifier of the present invention.
Wherein the figures include the following reference numerals:
1-a first differential eddy current probe; 2-a second differential eddy current probe; 3-workpiece.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the utility model, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, the differential eddy current displacement detector of this embodiment includes a high-frequency sine generator, a first differential eddy current probe 1, a second differential eddy current probe 2, a differential pre-detector, and a post-amplifier, where the high-frequency sine generator is connected to the first differential eddy current probe 1 and the second differential eddy current probe 2, the first differential eddy current probe 1 and the second differential eddy current probe 2 are connected to the differential pre-detector, and the differential pre-detector is connected to the post-amplifier; the first differential eddy current probe 1 and the second differential eddy current probe 2 have the same structure and respectively comprise an inductor and a resistor which are connected in series; the high-frequency sine generator sends the produced sine wave signal with fixed frequency to the first differential eddy current probe 1 and the second differential eddy current probe 2 to generate differential eddy current signals, and the differential eddy current signals are detected by the differential pre-detector, filtered and sent to the post-amplifier for amplification.
As shown in fig. 2, the first differential eddy current probe 1 and the second differential eddy current probe 2 are arranged oppositely, a workpiece detection position is arranged in the middle, when detection is required, the workpiece 3 is arranged on the workpiece detection position, displacement detection is started, and the detection process is as follows:
after a power supply is connected to a high-frequency sine generator, the high-frequency sine generator generates sine wave signals with fixed frequency and respectively provides the sine wave signals to the first differential eddy current probe 1 and the second differential eddy current probe 2; after the first differential eddy current probe 1 and the second differential eddy current probe 2 receive sine wave signals generated by a high-frequency sine generator, induced currents generated when a workpiece is displaced are respectively connected to a differential front detector; the differential pre-detector is used for carrying out differentiation, detection and filtering processing on signals of the first differential eddy current probe 1 and the second differential eddy current probe 2 and then sending the processed signals to the post-amplifier; the post amplifier is used for carrying out voltage bias and amplification on the signals processed by the differential pre-detector, and finally generating a forward voltage signal above 0V to represent workpiece displacement.
As shown in fig. 3, in this embodiment, the high-frequency sine generator includes a crystal oscillator, a first operational amplifier circuit and a second operational amplifier circuit, and the crystal oscillator generates a square wave signal with a fixed frequency and then sequentially filters the square wave signal through the first operational amplifier circuit and the second operational amplifier circuit to generate a high-frequency sine signal. The crystal oscillator is an active crystal oscillator.
Further, the first operational amplifier circuit and the second operational amplifier circuit both adopt an AD817 operational amplifier. The AD817 is a low-cost, low-power-consumption and high-speed operational amplifier, adopts a single power supply or a double power supply for power supply, and is very suitable for various signal conditioning and data acquisition applications. The breakthrough product also has high output current driving capability, can drive infinite capacitive loads, and still keeps excellent signal integrity. Of course, in this embodiment, other amplifiers capable of implementing the technical solution of the present application are also applicable besides the amplifier of this type.
As shown in fig. 4, in this embodiment, the differential pre-detector includes a differential amplifier U3 and a fourth operational amplifier U4, the first differential eddy current probe and the second differential eddy current probe are respectively connected in parallel with a capacitor to form a bridge circuit, and are connected to a third operational amplifier U3, and the third operational amplifier U3 is connected to a fourth operational amplifier U4.
In fig. 4, two dotted line frames on the left side are equivalent circuits of the first differential eddy current probe and the second differential eddy current probe, after high-frequency sinusoidal current signals are connected to the left sides of coil circuits of the first differential eddy current probe and the second differential eddy current probe, a bridge circuit is formed, the signals are output to a third operational amplifier U3, the signals are amplified and then connected to a detection circuit formed by a fourth operational amplifier U4, and the signals are filtered and then output to a post-amplifier.
Further, the INA103 is selected as the third operational amplifier U3; the INA103 is a very low noise, low distortion monolithic instrumentation amplifier whose current feedback circuit can achieve very wide bandwidth and excellent dynamic response, which is very suitable for low level audio signals. Of course, in this embodiment, other amplifiers capable of implementing the technical solution of the present application are also applicable besides the amplifier of this type.
Further, the fourth operational amplifier U4 is AD835, where the AD835 is a complete four-quadrant voltage output analog multiplier and is manufactured by an advanced dielectric isolation complementary bipolar process.
As shown in fig. 5, in the present embodiment, the post-amplifier includes a fifth operational amplifier U5 and a sixth operational amplifier U6, and the output terminal of the fifth operational amplifier U5 is connected to the input terminal of the sixth operational amplifier U6. The post amplifier is used for amplifying the signal of the differential pre-detector and improving the output sensitivity of the sensor; the post-amplifier is biased by a circuit composed of an operational amplifier U5, and then the gain of the signal is realized through an output amplifying circuit composed of a U6.
Further, the OPA192 is selected as the fifth operational amplifier U5, and the OPA192 is a new generation 36V e-trim operational amplifier with excellent DC accuracy and AC performance, including rail-to-rail input/output, low offset (typical value: +5 μ V), low offset drift (typical value: +0.2 μ V/9C) and 10MHz bandwidth. Of course, in this embodiment, other amplifiers capable of implementing the technical solution of the present application are also applicable besides the amplifier of this type.
Furthermore, the sixth operational amplifier is AD8421, and the AD8421 is a low-cost, low-power consumption, extremely low-noise, ultra-low bias current and high-speed instrument amplifier, and is particularly suitable for various signal conditioning and data acquisition applications. The breakthrough product has the highest Common Mode Rejection Ratio (CMRR) at present, and can extract low-level signals under the condition of high-frequency common mode noise in a wide temperature range. Of course, in this embodiment, other amplifiers capable of implementing the technical solution of the present application are also applicable besides the amplifier of this type.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular is intended to include the plural unless the context clearly dictates otherwise, and it should be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of features, steps, operations, devices, components, and/or combinations thereof.
It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are capable of operation in sequences other than those illustrated or described herein.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The differential eddy current displacement detection device is characterized by comprising a high-frequency sine generator, a first differential eddy current probe, a second differential eddy current probe, a differential pre-detector and a post-amplifier, wherein the high-frequency sine generator, the first differential eddy current probe and the second differential eddy current probe are connected with the differential pre-detector, and the differential pre-detector is connected with the post-amplifier; the first differential eddy current probe and the second differential eddy current probe have the same structure and respectively comprise an inductor and a resistor which are connected in series; the high-frequency sine generator sends the produced sine wave signal with fixed frequency to the first differential eddy current probe and the second differential eddy current probe to generate differential eddy current signals, and the differential eddy current signals are detected by the differential pre-detector, filtered and sent to the post-amplifier for amplification.
2. The differential eddy current displacement transducer of claim 1, wherein the first and second differential eddy current probes are oppositely disposed.
3. The differential eddy current displacement testing device according to claim 1, wherein the high-frequency sine generator comprises a crystal oscillator, a first operational amplifier circuit and a second operational amplifier circuit, and the crystal oscillator generates a square wave signal with a fixed frequency, and then the square wave signal is filtered by the first operational amplifier circuit and the second operational amplifier circuit in sequence to generate a high-frequency sine signal.
4. The differential eddy current displacement testing device according to claim 3, wherein the crystal oscillator is an active crystal oscillator.
5. The differential eddy current displacement sensor as claimed in claim 3, wherein the first operational amplifier circuit and the second operational amplifier circuit are both AD817 operational amplifiers.
6. The differential eddy current displacement detector according to claim 1, wherein the differential pre-detector comprises a differential amplifier U3 and a fourth operational amplifier U4, the first differential eddy current probe and the second differential eddy current probe are respectively connected in parallel with a capacitor to form a bridge circuit, and are connected to a third operational amplifier U3, and the third operational amplifier U3 is connected to a fourth operational amplifier U4.
7. The differential eddy current displacement testing apparatus of claim 6, wherein the third operational amplifier U3 is INA 103; the fourth operational amplifier U4 is AD 835.
8. The differential eddy current displacement sensor of claim 1, wherein the post-amplifier comprises a fifth operational amplifier U5 and a sixth operational amplifier U6, and the output of the fifth operational amplifier U5 is connected to the input of the sixth operational amplifier U6.
9. The differential eddy current displacement testing device according to claim 8, wherein the OPA192 is selected as the fifth operational amplifier U5.
10. The differential eddy current displacement testing device according to claim 8, wherein the sixth operational amplifier is AD 8421.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121865425.0U CN216115842U (en) | 2021-08-10 | 2021-08-10 | Differential eddy current displacement detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121865425.0U CN216115842U (en) | 2021-08-10 | 2021-08-10 | Differential eddy current displacement detector |
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| Publication Number | Publication Date |
|---|---|
| CN216115842U true CN216115842U (en) | 2022-03-22 |
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| CN202121865425.0U Active CN216115842U (en) | 2021-08-10 | 2021-08-10 | Differential eddy current displacement detector |
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- 2021-08-10 CN CN202121865425.0U patent/CN216115842U/en active Active
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