CN216668576U

CN216668576U - Probe of eddy current displacement sensor

Info

Publication number: CN216668576U
Application number: CN202220911080.6U
Authority: CN
Inventors: 尹静; 赵国锋; 曹龙轩; 李伟; 李明夏
Original assignee: Anhui Jianxing Technology Co ltd; Hefei Normal University
Current assignee: Anhui Jianxing Technology Co ltd; Hefei Normal University
Priority date: 2022-04-20
Filing date: 2022-04-20
Publication date: 2022-06-03
Anticipated expiration: 2032-04-20

Abstract

The utility model discloses an eddy current displacement sensor probe, and belongs to the technical field of sensors. The micro-crystal glass substrate comprises a micro-crystal glass substrate, wherein a silver electrode layer is arranged on one side surface of the micro-crystal glass substrate, an annular coil is formed on the surface of the silver electrode layer through photoetching or etching, a lead hole penetrating through the thickness of the micro-crystal glass substrate is formed in the micro-crystal glass substrate, and conductive silver adhesive conducted with the silver electrode layer is filled in the lead hole. Aiming at the problems of insufficient stability of a mechanical structure of the probe and stress deformation caused by temperature influence in the prior art, the utility model provides the eddy current displacement sensor probe based on the welding process coil, and the mechanical stability of the probe under long-time work can be ensured by releasing the stress generated between the coil and a substrate structure.

Description

Probe of eddy current displacement sensor

Technical Field

The utility model belongs to the technical field of sensors, and particularly relates to a probe of an eddy current displacement sensor.

Background

The eddy current displacement sensor is a non-contact precise displacement sensor based on the electromagnetic induction principle and mainly comprises a probe, a target plate, a signal processing circuit and the like. The probe mainly comprises a loop coil and a supporting base structure, a target plate is usually a planar metal sheet with a certain thickness, generally less than 1mm, and a measured object can be directly used as the target plate in some cases, such as an axis or a plane formed by a good conductor. When a high-frequency alternating current is conducted in the annular coil, the coil excites a high-frequency magnetic field in the axial region, so that eddy currents are formed on the target plate plane perpendicular to the axial direction of the coil. The strength of the generated eddy current is related to the distance between the annular coil and the target board, the equivalent impedance change of the annular coil can indirectly reflect the change of the eddy current strength, and the signal processing circuit is simultaneously used for exciting the annular coil and measuring the equivalent impedance change of the annular coil.

One of the core indicators of a precision displacement sensor is its stability, including temperature stability and time stability. Particularly, the stability of the eddy current displacement sensor is naturally influenced by the probe, the target plate and the signal processing circuit, and the stability can be further subdivided into mechanical stability and circuit stability; the mechanical stability mainly refers to whether a gap between the probe and a target plate can be kept stable or not, and the circuit stability refers to whether the output voltage of the signal processing circuit is stable or not when the gap between the probe and the target plate is constant; however, in practical applications, the two will affect each other, and generally need to be considered comprehensively in design.

The probe can be composed of various annular coil + substrate structures, and can be divided into the following types according to the types of the coils: enameled coils, PCB/FPC coils, multilayer ceramic coils (LTCC), etc.; the manufacturing process of the coil can be divided into the following steps: wire-winding, electroplating, and the like. The substrate structure is used for supporting and externally clamping the coil, and can be a plane structure or a long cylindrical structure according to different application scenes. In precision measurement, in order to ensure the mechanical stability of the probe, the substrate structure must be made of a special material with high strength and low expansion coefficient, such as glass or ceramic, which has a thermal expansion coefficient as low as several ppm/DEG C and has a certain machinability. However, it is not enough that the coil is pasted to the substrate structure through the AB glue in the conventional probe design, including the enameled coil, the PCB/FPC coil and the LTCC, and because the coil is made of a different material from the substrate structure and is tightly pasted together through the AB glue, when the environmental temperature changes, the coil and the substrate structure generate stress to cause the deformation of the probe, and the mechanical stability of the probe cannot be guaranteed. Therefore, it is urgently needed to design an eddy current displacement sensor probe, which can ensure the mechanical stability of the probe under long-time work by releasing the stress generated between the coil and the substrate structure.

Through retrieval, the technology related to the probe of the eddy current displacement sensor has been disclosed in patent documents, such as Chinese patent application numbers: 2016108587569, publication number: CN106500580A, publication date: 2017, 03, 15, discloses an eddy current displacement sensor, a probe and a coil thereof, wherein the probe comprises: the winding bracket is integrally a rotary body and is provided with a first end and a second end along the axis direction, wherein a matching part is formed at a position close to the first end; the coil is arranged on the winding bracket; the whole coil is an annular rotary body, a through hole matched with the matching part is formed in the middle of the coil, and a variable inner diameter section is formed on the inner surface of the coil, which is located at the through hole, along the axial direction. The eddy current displacement sensor, the probe and the coil thereof provided by the utility model can meet the requirements of installation and detection at the same time.

SUMMERY OF THE UTILITY MODEL

1. Problems to be solved

Aiming at the problems of insufficient stability of a mechanical structure of the probe and stress deformation caused by temperature influence in the prior art, the utility model provides the eddy current displacement sensor probe based on the welding process coil, and the mechanical stability of the probe under long-time work can be ensured by releasing the stress generated between the coil and a substrate structure.

2. Technical scheme

In order to solve the above problems, the present invention adopts the following technical solutions.

The utility model relates to an eddy current displacement sensor probe, which comprises a microcrystalline glass substrate, wherein a silver electrode layer is arranged on one side surface of the microcrystalline glass substrate, an annular coil is photoetched or etched on the surface of the silver electrode layer, a lead hole penetrating through the microcrystalline glass substrate is formed in the microcrystalline glass substrate, and conductive silver adhesive communicated with the silver electrode layer is filled in the lead hole.

Preferably, one side surface of the microcrystalline glass substrate is a smooth surface after grinding and polishing, and a silver electrode layer is arranged on the smooth surface of the microcrystalline glass substrate in an evaporation mode.

Preferably, a thin copper metal layer is welded on the surface of the silver electrode layer, and the annular coil is arranged on the surface of the thin copper metal layer in a photoetching or etching mode.

Preferably, the thickness of the silver electrode layer is 1-10 μm, and the thickness of the thin copper metal layer is more than or equal to 100 μm.

Preferably, the annular coil has a plurality of coils arranged in a continuous annular shape, two ends of the coil are respectively a central joint point and an outer ring joint point, the central joint point is located at a circle center position of the annular coil, and the outer ring joint point is located at an end point of a coil at a radial outer side of the annular coil.

Preferably, the positions of the microcrystalline glass substrate corresponding to the central joint point and the outer ring joint point of the annular coil are provided with lead holes penetrating through the thickness of the microcrystalline glass substrate, and each lead hole is filled with conductive silver adhesive conducted with the silver electrode layer.

3. Advantageous effects

Compared with the prior art, the utility model has the beneficial effects that:

(1) according to the eddy current displacement sensor probe, the microcrystalline glass substrate is used as the main body structure of the probe, so that the thermal expansion deformation of the probe can be effectively reduced, the thermal expansion coefficient of microcrystalline glass is as low as 0.05 ppm/DEG C, and compared with a traditional metal probe (the thermal expansion coefficient is 10-20 ppm/DEG C) and a ceramic probe (the thermal expansion coefficient is 3-8 ppm/DEG C), the temperature stability of the probe is improved by more than two orders of magnitude by the substrate structure made of the microcrystalline glass material.

(2) According to the eddy current displacement sensor probe, the welding process coil in the scheme is adopted, so that the annular coil can be closely attached to the microcrystalline glass substrate, the reliability is extremely high, and compared with the traditional adhesive connection, the eddy current displacement sensor probe is free from the problems of adhesive fatigue falling and aging failure and convenient to use for a long time; meanwhile, the annular coil is not connected by gluing any more, the annular coil and the microcrystalline glass substrate are in spaced contact constraint, a gap exists between the coil and the coil, and although the annular coil and the microcrystalline glass substrate are made of different materials and can generate stress during temperature change, the stress can be effectively released in the gap and cannot be accumulated, and the stability is high compared with the prior art.

(3) According to the eddy current displacement sensor probe, due to the adoption of the welding process coil, the copper thickness of the annular coil can be more than hundred microns, which cannot be achieved by the existing electroplating technology, so that the resistance of the annular coil can be effectively reduced, and the temperature stability of the eddy current displacement sensor is improved.

Drawings

FIG. 1 is a schematic cross-sectional view of an eddy current displacement sensor probe according to the present invention;

fig. 2 is a schematic top view of the toroidal coil of the present invention.

In the figure:

1. a glass-ceramic substrate; 2. conductive silver paste; 3. a loop coil; 31. a central joint point; 32. an outer ring joint point; 4. and a silver electrode layer.

Detailed Description

The utility model is further described with reference to specific embodiments and the accompanying drawings.

Example 1

As shown in fig. 1, the eddy current displacement sensor probe according to the embodiment includes a microcrystalline glass substrate 1, which can be processed into various shapes according to practical application scenarios, and the microcrystalline glass substrate 1 is used as a main structure of the probe, so that thermal expansion deformation of the probe can be effectively reduced, and the thermal expansion coefficient of the microcrystalline glass is as low as 0.05 ppm/deg.c, and compared with a conventional metal probe (thermal expansion coefficient 10-20 ppm/deg.c) and a ceramic probe (thermal expansion coefficient 3-8 ppm/deg.c), the temperature stability of the probe is improved by more than two orders of magnitude by the substrate structure made of the microcrystalline glass material.

In the embodiment, a silver electrode layer 4 is arranged on one side surface of the microcrystalline glass substrate 1, and the silver electrode layer 4 is evaporated on the welding plane of the microcrystalline glass substrate 1 by a physical method. The surface of the silver electrode layer 4 is etched with the annular coil 3 by photoetching, and the annular coil 3 is tightly connected with the silver electrode layer 4 by a metal welding process. Specifically, in this embodiment, one side surface of the microcrystalline glass substrate 1 is polished and polished to be smooth, and the surface roughness of the microcrystalline glass substrate 1 is reduced by polishing and polishing to be smooth. A silver electrode layer 4 is arranged on the smooth surface of the microcrystalline glass substrate 1 in an evaporation mode, the thickness of the silver electrode layer 4 is 1-10 micrometers, and specifically, the thickness of the silver electrode layer 4 is 5 micrometers in the embodiment.

In this embodiment, the microcrystalline glass substrate 1 is provided with a lead hole penetrating through the thickness thereof, and the lead hole is filled with conductive silver paste 2 conducting with the silver electrode layer 4. The annular coil 3 has a plurality of coils arranged in a continuous annular shape, two ends of the coil are respectively a central joint point 31 and an outer ring joint point 32, the central joint point 31 is located at the position of the circle center of the annular coil 3, and the outer ring joint point 32 is located at the end point of the coil at the radial outer side of the annular coil 3. In this embodiment, lead holes penetrating the thickness of the microcrystalline glass substrate 1 are formed at positions corresponding to the central joint point 31 and the outer ring joint point 32 of the annular coil 3, and conductive silver paste 2 conducting with the silver electrode layer 4 is filled in each lead hole. The conductive silver paste 2 is used to connect two terminals (i.e., the center terminal point 31 and the outer ring terminal point 32) of the toroidal coil 3 and serves as a lead wire of the toroidal coil 1.

By adopting the welding process coil of the embodiment, the annular coil 3 can be closely attached to the microcrystalline glass substrate 1, the reliability is extremely high, and compared with the traditional adhesive connection, the problems of adhesive fatigue falling and aging failure do not exist, and the long-term use is convenient; meanwhile, the annular coil 3 is not connected with the microcrystalline glass substrate 1 in an adhesive manner, the annular coil 3 is in spaced contact constraint with the microcrystalline glass substrate 1, and a gap exists between the coil and the coil, although the annular coil 3 and the microcrystalline glass substrate 1 are made of different materials and can generate stress during temperature change, the stress can be effectively released in the gap and cannot be accumulated, and the stability is high compared with that of the prior art.

The surface of the silver electrode layer 4 of the embodiment is welded with a thin copper metal layer, the annular coil 3 is arranged on the surface of the thin copper metal layer in a photoetching or etching mode, and the thickness of the thin copper metal layer is more than or equal to 100 mu m. Specifically, the thickness of the thin copper metal layer in this embodiment is 100 μm. By adopting the welding process coil of the embodiment, the copper thickness of the annular coil 3 can be more than hundred microns, which cannot be achieved by the existing electroplating technology, so that the resistance of the annular coil 3 can be effectively reduced, and the temperature stability of the eddy current displacement sensor is improved.

In the embodiment, firstly, a microcrystalline glass substrate 1 is processed, two lead holes are processed in the microcrystalline glass substrate 1, and after machining is completed, grinding and polishing are performed on one surface of the microcrystalline glass substrate 1, so that the surface roughness of the microcrystalline glass substrate 1 is reduced, and the microcrystalline glass substrate 1 presents a smooth surface; then, a silver electrode layer 4 is vapor-plated on the smooth surface of the microcrystalline glass substrate 1, and conductive silver adhesive 2 which is conducted with the silver electrode layer 4 is filled in an internal lead hole of the microcrystalline glass substrate 1; and preparing a thin copper sheet, tightly welding the thin copper sheet to the surface of the silver electrode layer 4 to form a copper-silver composite metal layer tightly connected with the microcrystalline glass substrate 1, and finally processing and forming the designed pattern of the annular coil 3 on the copper-silver composite metal layer by a photoetching or etching method to finish the processing of the probe in the embodiment.

Example 2

The basic structure of the probe of the eddy current displacement sensor in this embodiment is the same as that in embodiment 1, except that the thickness of the silver electrode layer 4 in this embodiment is 1 μm; the thickness of the thin copper metal layer is 120 mu m.

Example 3

The basic structure of the probe of the eddy current displacement sensor in this embodiment is the same as that in embodiment 1, except that the thickness of the silver electrode layer 4 in this embodiment is 10 μm; the thickness of the thin copper metal layer is 108 μm.

The examples described herein are merely illustrative of the preferred embodiments of the present invention and do not limit the spirit and scope of the present invention, and various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the design concept of the present invention shall fall within the protection scope of the present invention.

Claims

1. An eddy current displacement sensor probe is characterized in that: the novel glass-ceramic substrate comprises a glass-ceramic substrate (1), wherein a silver electrode layer (4) is arranged on one side face of the glass-ceramic substrate (1), an annular coil (3) is formed on the surface of the silver electrode layer (4) through photoetching or etching, a lead hole penetrating through the thickness of the glass-ceramic substrate is formed in the glass-ceramic substrate (1), and conductive silver adhesive (2) communicated with the silver electrode layer (4) is filled in the lead hole.

2. An eddy current displacement sensor probe according to claim 1, wherein: one side surface of the microcrystalline glass substrate (1) is a smooth surface after grinding and polishing, and a silver electrode layer (4) is arranged on the smooth surface of the microcrystalline glass substrate (1) in an evaporation mode.

3. An eddy current displacement sensor probe according to claim 2, wherein: a thin copper metal layer is welded on the surface of the silver electrode layer (4), and the annular coil (3) is arranged on the surface of the thin copper metal layer in a photoetching or etching mode.

4. An eddy current displacement sensor probe according to claim 3, wherein: the thickness of the silver electrode layer (4) is 1-10 mu m, and the thickness of the thin copper metal layer is larger than or equal to 100 mu m.

5. An eddy current displacement sensor probe according to any one of claims 1 to 4, wherein: the annular coil (3) is provided with a plurality of coils which are continuously and annularly arranged, two ends of each coil are respectively a central joint point (31) and an outer ring joint point (32), the central joint point (31) is located at the position of the circle center of the annular coil (3), and the outer ring joint point (32) is located at the end point of the coil on the radial outer side of the annular coil (3).

6. An eddy current displacement sensor probe according to claim 5, wherein: lead holes penetrating through the thickness of the microcrystalline glass substrate (1) are formed in positions corresponding to the central joint point (31) and the outer ring joint point (32) of the annular coil (3), and conductive silver adhesive (2) communicated with the silver electrode layer (4) is filled in each lead hole.