Dielectric Spectroscopy Sensor for Online Monitoring of Oil Quality

Abstract

The present application discloses a dielectric spectrum sensor for online monitoring of oil quality, including a shell and a measuring unit. The shell includes an outer shell and an inner shell, and an annular cavity is formed between the outer shell and the inner shell. The annular cavity includes a first annular cavity, a third annular cavity and a second annular cavity. The first annular cavity, the third annular cavity and the second annular cavity are arranged in sequence along the axial direction. A guide groove extending along a spiral line is provided in the first annular cavity, and a confluence groove extending along a spiral line is provided in the second annular cavity. The measuring unit is arranged in the third annular cavity, including an inner electrode assembly and an outer electrode assembly arranged coaxially. The present application realizes fast and accurate online measurement of the dielectric spectrum of oil.

Description

Technical Field

[0001] The present application relates to the technical field of oil quality detection sensors, and in particular to a dielectric spectrum sensor for online monitoring of oil quality. Background Art

[0002] With the continuous improvement of industrial automation, online oil monitoring technology plays an increasingly important role in industrial production. Dielectric spectrum analysis technology can measure the dielectric response characteristics of oil in a wide frequency range. Compared with traditional single-frequency dielectric constant measurement, it can obtain richer oil molecular structure information and more comprehensively reflect the aging degree, contamination status and composition changes of oil.

[0003] At present, the dielectric spectrum measurement of oil mainly adopts the method of laboratory offline analysis. However, this measurement method has disadvantages such as long measurement cycle, professional operation, large equipment size, etc., which is difficult to meet the needs of industrial sites for real-time monitoring of oil quality.

[0004] Therefore, how to design a sensor that can achieve fast and accurate online measurement of oil dielectric spectrum is a technical problem that needs to be solved urgently in this field. Summary of the invention

[0005] The purpose of the present application is to provide a dielectric spectrum sensor for online monitoring of oil quality, so as to solve the technical problem in the prior art that it is difficult to achieve fast and accurate online measurement of oil dielectric spectrum.

[0006] An embodiment of the present application provides a dielectric spectrum sensor for online monitoring of oil quality, comprising: a shell, the shell comprising an outer shell and an inner shell, an annular cavity is formed between the outer shell and the inner shell, the annular cavity comprises a first annular cavity, a second annular cavity and a third annular cavity, the first annular cavity, the third annular cavity and the second annular cavity are arranged in sequence along the axial direction, a guide groove is provided in the first annular cavity, a confluence groove is provided in the second annular cavity, and the guide groove and the confluence groove both extend along a spiral line; and a measuring unit, the measuring unit is arranged in the third annular cavity, the measuring unit comprises an inner electrode assembly and an outer electrode assembly, and the inner electrode assembly and the outer electrode assembly are coaxially arranged.

[0007] In the above-mentioned dielectric spectrum sensor, the first annular cavity includes a first annular segment and a second annular segment arranged in sequence along the axial direction, the cross-sectional area of ​​the first annular segment is larger than the cross-sectional area of ​​the second annular segment, a first step surface is formed between the first annular segment and the second annular segment, the axial length of the first annular segment is larger than the axial length of the second annular segment, the guide groove is arranged on the inner wall surface of the first annular segment, and the plurality of guide grooves are evenly distributed along the circumferential direction.

[0008] In the above-mentioned dielectric spectrum sensor, the second annular cavity includes a third annular segment and a fourth annular segment arranged in sequence along the axial direction, the cross-sectional area of ​​the third annular segment is smaller than the cross-sectional area of ​​the fourth annular segment, a second step surface is formed between the third annular segment and the fourth annular segment, the axial length of the fourth annular segment is greater than the axial length of the third annular segment, the confluence groove is arranged on the inner wall surface of the fourth annular segment, and the plurality of confluence grooves are evenly distributed along the circumferential direction.

[0009] In the above-mentioned dielectric spectrum sensor, the cross-sectional area of ​​the third annular cavity gradually decreases along the axial direction, the inner wall surface and the outer wall surface of the third annular cavity are both conical, the tapers of the inner wall surface and the outer wall surface are the same, and a first arc-shaped transition surface is provided at the connection between the third annular cavity and the second annular segment, and a second arc-shaped transition surface is provided at the connection between the third annular cavity and the third annular segment.

[0010] The above-mentioned dielectric spectrum sensor also includes an oil inlet channel and an oil outlet channel, the oil inlet channel includes a first oil inlet section and a second oil inlet section, the first oil inlet section extends axially, the second oil inlet section extends radially, one end of the first oil inlet section is connected to the oil inlet, and the other end is connected to one end of the second oil inlet section, and the other end of the second oil inlet section is connected to the first annular cavity, the oil outlet channel includes a first oil outlet section and a second oil outlet section, the first oil outlet section extends axially, the second oil outlet section extends radially, one end of the first oil outlet section is connected to the oil outlet, and the other end is connected to one end of the second oil outlet section, and the other end of the second oil outlet section is connected to the second annular cavity.

[0011] In the above-mentioned dielectric spectrum sensor, a diffusion part is provided at the connection between the second oil inlet section and the first annular section, and the diffusion part includes a plurality of diffusion channels, and the plurality of diffusion channels are evenly distributed along the circumferential direction. The inlet end of each diffusion channel is connected to the second oil inlet section, and the outlet end is connected to the corresponding guide groove, and the cross-sectional area of ​​the diffusion channel gradually increases from the inlet end to the outlet end; a contraction structure is provided at the connection between the second oil outlet section and the fourth annular section, and the contraction structure includes a plurality of contraction channels, and the plurality of contraction channels are evenly distributed along the circumferential direction. The inlet end of each contraction channel is connected to the corresponding confluence groove, and the outlet end is connected to the second oil outlet section, and the cross-sectional area of ​​the contraction channel gradually decreases from the inlet end to the outlet end.

[0012] In the above-mentioned dielectric spectrum sensor, the outer shell and the inner shell are coaxially positioned through a detachable positioning assembly, and the positioning assembly includes a plurality of positioning grooves and a plurality of positioning blocks, and the plurality of positioning grooves are evenly distributed along the circumference of the outer shell, and the plurality of positioning blocks correspond one-to-one to the plurality of positioning grooves, and each of the positioning grooves includes a mounting portion and a limiting portion, the mounting portion extends in the axial direction, and the limiting portion extends in the circumferential direction, and each of the positioning blocks includes a sliding portion and a clamping portion, the sliding portion extends in the axial direction, and the clamping portion extends in the circumferential direction.

[0013] In the above-mentioned dielectric spectrum sensor, the inner electrode assembly includes: an inner electrode body, which is cylindrical and whose outer surface is a measuring surface; and an inner electrode support frame, which includes a support arm connected to the inner electrode body and the inner shell.

[0014] In the above-mentioned dielectric spectrum sensor, the outer electrode assembly includes: an outer electrode body, which is cylindrical and whose inner surface is a measuring surface; and an outer electrode support frame, which includes a support ring connected to the outer electrode body and the outer shell.

[0015] In the above dielectric spectrum sensor, the inner electrode support frame and the outer electrode support frame are both made of elastic material.

[0016] The dielectric spectrum sensor provided in this application realizes fast and accurate online measurement of the dielectric spectrum of oil through the following technical solutions:

[0017] First, the present application forms an annular cavity including a first annular cavity, a third annular cavity and a second annular cavity between the outer shell and the inner shell, and arranges a guide groove extending along the spiral line in the first annular cavity and a confluence groove extending along the spiral line in the second annular cavity, thereby forming a unique flow field control structure, so that the oil forms a stable spiral flow field when flowing through the sensor. When local flow disturbance occurs, the centrifugal force generated by the spiral motion can quickly suppress the disturbance and return the fluid to a stable state. At the same time, the spiral flow field extends the flow path of the oil in the sensor, so that the oil has more time to complete speed adjustment and flow state conversion, ensuring that the oil is in full contact with the measuring electrode, thereby improving the measurement accuracy.

[0018] Secondly, the present application sets the measuring unit in the third annular cavity, and sets the inner electrode assembly and the outer electrode assembly coaxially. Since the third annular cavity is located between the first annular cavity and the second annular cavity, the oil flowing through the area has completed the initial speed adjustment and flow state conversion, and is in the most stable flow state, ensuring the uniformity of the oil in the measuring area and significantly improving the measurement accuracy. At the same time, the coaxial setting of the inner electrode assembly and the outer electrode assembly ensures the formation of a uniform electric field distribution between the measuring electrodes, avoiding the influence of local electric field distortion on the measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of a dielectric spectrum sensor for online monitoring of oil quality provided in an embodiment of the present application.

[0020] Figure 2 yes Figure 1 A cross-sectional view of a dielectric spectroscopy sensor for online monitoring of oil quality is shown.

[0021] Figure 3 yes Figure 2 A cross-sectional view taken along line AA' of a dielectric spectrum sensor for online monitoring of oil quality is shown.

[0022] Figure 4 yes Figure 3 Schematic diagram of area B shown. DETAILED DESCRIPTION

[0023] The specific implementation methods of the present application are described in detail below with reference to the accompanying drawings.

[0024] The terms "first", "second" and similar words do not indicate any order, quantity or importance, but are only used to distinguish different technical features. The term "plurality" and similar words mean two or more, unless otherwise clearly defined.

[0025] like Figure 1 As shown, in order to solve the technical problem that it is difficult to achieve fast and accurate online measurement of oil dielectric spectrum in the prior art, the present application provides a dielectric spectrum sensor 20 for online monitoring of oil quality.

[0026] The dielectric spectrum sensor 20 of the present application can be applied to the oil circulation system of industrial equipment, and the oil circulation system includes a main oil tank, an auxiliary oil tank, an oil pump group, a filter device, a cooling device, a pipeline and a monitoring device. The main oil tank is used to store working oil, the auxiliary oil tank is used to replenish and adjust the oil, the oil pump group is used to drive the oil to circulate in the oil circulation system, and the filter device and the cooling device are used to purify and cool the circulating oil respectively.

[0027] A plurality of detection units are arranged at key monitoring points of the oil circulation system, and each detection unit is equipped with the dielectric spectrum sensor 20 of the present application. The detection units are arranged at positions including: the outlet of the main oil tank, before and after the filter device, the outlet of the cooling device, etc. The oil quality changes at these positions have an important indicative effect on the operating status of the equipment, so detection units are arranged at these positions.

[0028] Each detection unit includes a dielectric spectrum sensor 20, a shunt detection branch, a data acquisition device and a control device. The shunt detection branch is arranged in parallel with the main oil circuit, and the shunt detection branch includes an oil inlet pipe section, a measuring pipe section 10 and an oil outlet pipe section, and the dielectric spectrum sensor 20 is arranged on the measuring pipe section 10. The oil inlet pipe section is connected to the main oil circuit through an electric regulating valve, and the oil outlet pipe section is connected to the main oil circuit through a back pressure valve. The inner diameter of the measuring pipe section 10 is smaller than the inner diameters of the oil inlet pipe section and the oil outlet pipe section, and the measuring pipe section 10 is coaxially arranged with the measuring chamber of the dielectric spectrum sensor 20. A flow regulating device is provided on the oil inlet pipe section, and the flow regulating device includes a throttle valve and a flow stabilizing valve arranged in series, which are used to adjust the oil in a turbulent state to a laminar state. A pressure balancing device is provided on the oil outlet pipe section, and the pressure balancing device includes a back pressure valve and a pressure buffer arranged in series, which are used to eliminate the influence of oil pressure fluctuations on the measurement area.

[0029] On the shunt detection branch, a pressure sensor and a temperature sensor are respectively arranged upstream and downstream of the dielectric spectrum sensor 20. Among them, the first pressure sensor is arranged on the oil inlet pipe section, and the second pressure sensor is arranged on the oil outlet pipe section. The two pressure sensors are connected to the measuring pipe section 10 through the pressure measurement pipeline. The temperature sensor includes a first temperature sensor and a second temperature sensor, the first temperature sensor is arranged on the oil inlet pipe section, and the second temperature sensor is arranged on the measuring pipe section 10. The flow sensor is arranged on the oil inlet pipe section, and is located downstream of the flow regulating device. The signal output ends of the pressure sensor, the temperature sensor and the flow sensor are electrically connected to the signal input end of the data acquisition device respectively. The data collected by these sensors are used to establish a compensation model of the oil dielectric spectrum with temperature and pressure, so as to realize real-time correction of the measurement results.

[0030] The data acquisition device includes a data acquisition device, a signal conditioning circuit and a communication module. The data acquisition device has multiple signal input channels, which are electrically connected to the measurement signal output end of the dielectric spectrum sensor 20, the signal output end of the pressure sensor, the signal output end of the temperature sensor and the signal output end of the flow sensor. The signal conditioning circuit includes a signal amplification unit, a filtering unit and an analog-to-digital conversion unit. The signal amplification unit is used to amplify weak sensor signals, the filtering unit is used to filter out interference signals in industrial environments, and the analog-to-digital conversion unit is used to convert analog signals into digital signals. The communication module adopts the industrial Ethernet protocol and exchanges data with the monitoring device through a network switch.

[0031] The control device consists of a programmable controller, an execution device and an operation panel. The signal input end of the programmable controller is electrically connected to the data output end of the data acquisition device, and the signal output end is electrically connected to the control end of the execution device. The programmable controller executes the preset control algorithm and outputs the control signal according to the real-time collected pressure, temperature and flow data. The execution device includes an electric actuator and a pneumatic actuator. The electric actuator is mechanically connected to the throttle valve and the steady flow valve, and the pneumatic actuator is mechanically connected to the back pressure valve.

[0032] The monitoring device connects the communication modules of all detection units through industrial Ethernet to realize centralized monitoring of the entire oil circulation system. The monitoring device includes a server, a database and a display screen. The data input end of the server is electrically connected to the communication module of each detection unit through a network switch, and the server is used to perform comprehensive processing on the collected data.

[0033] In practical applications, the oil enters the oil inlet section of the shunt detection branch from the main oil circuit through the electric regulating valve. Through the regulation of the throttle valve and the steady flow valve of the flow regulating device, the oil changes from a turbulent state to a laminar state. After the oil in the laminar state enters the measuring pipe section 10, a stable flow field is formed in the measuring area of ​​the dielectric spectrum sensor 20. The inner electrode 204 and the outer electrode 203 of the dielectric spectrum sensor 20 detect the complex dielectric constant of the oil, the first temperature sensor and the second temperature sensor detect the oil temperature, the first pressure sensor and the second pressure sensor detect the oil pressure, and the flow sensor detects the oil flow. The output signals of these sensors are processed by the signal conditioning circuit of the data acquisition device, digitally converted by the data acquisition device, and then transmitted to the server of the monitoring device through the communication module. The server performs compensation calculation on the dielectric spectrum measurement value according to the preset data processing algorithm, combined with the temperature, pressure and flow parameters, to obtain accurate oil quality data.

[0034] The dielectric spectrum of oil reflects the dielectric properties of oil at different frequencies, and its core parameter is the complex dielectric constant. The complex dielectric constant is a complex number, including the real part (ε') and the imaginary part (ε"), which can be expressed as: ε* = ε' - jε", where j is the imaginary unit. The real part represents the ability of oil to store electric field energy, and the imaginary part represents the ability of oil to lose electric field energy.

[0035] The frequency dispersion characteristics in the dielectric spectrum are closely related to the molecular structure and composition of the oil. For example, in the low frequency band (1Hz-1kHz), the dielectric spectrum mainly reflects the orientation polarization characteristics of large molecules in the oil; in the medium frequency band (1kHz-1MHz), it mainly reflects the polarization characteristics of medium-sized molecules; in the high frequency band (1MHz-10MHz), it mainly reflects the polarization characteristics of small molecules. Therefore, by analyzing the changes in the dielectric spectrum, key quality parameters such as the degree of oxidation, moisture content, and acid value of the oil can be detected.

[0036] like Figure 1 As shown, in one embodiment of the present application, the dielectric spectrum sensor 20 includes a housing 201, a measuring unit and a signal processing unit 202. The dielectric spectrum sensor 20 is used to measure the dielectric spectrum of the oil in a frequency range of 1 Hz to 10 MHz, and to evaluate the quality state of the oil by analyzing the dielectric response characteristics at different frequencies.

[0037] like Figures 2 to 4 As shown, an annular cavity is provided inside the housing 201 to form an annular channel for oil circulation. The housing 201 includes an outer housing 2011 and an inner housing 2012 .

[0038] The inner wall of the outer shell and the outer wall of the inner shell together form an annular cavity, which includes a first annular cavity 206, a second annular cavity 208 and a third annular cavity 207, which are arranged in sequence along the axial direction. The first annular cavity 206 is surrounded by the first inner wall segment and the fourth outer wall segment, wherein the first inner wall segment is the inner wall segment on the inner wall of the outer shell located at one end in the axial direction, the fourth outer wall segment is the outer wall segment on the outer wall of the inner shell corresponding to the first inner wall segment, and an annular space is formed between the first inner wall segment and the fourth outer wall segment, which is the first annular cavity 206. The second annular cavity 208 is surrounded by the third inner wall segment and the sixth outer wall segment, wherein the third inner wall segment is the inner wall segment on the inner wall of the outer shell located at the other end in the axial direction, the sixth outer wall segment is the outer wall segment on the outer wall of the inner shell corresponding to the third inner wall segment, and an annular space is formed between the third inner wall segment and the sixth outer wall segment, which is the second annular cavity 208. The third annular cavity 207 is surrounded by the second inner wall segment and the fifth outer wall segment, wherein the second inner wall segment is the inner wall segment on the inner wall of the outer shell body between the first inner wall segment and the third inner wall segment, and the fifth outer wall segment is the outer wall segment on the outer wall of the inner shell body between the fourth outer wall segment and the sixth outer wall segment, and an annular space is formed between the second inner wall segment and the fifth outer wall segment, and the annular space is the third annular cavity 207. The first annular cavity 206, the third annular cavity 207 and the second annular cavity 208 are arranged in sequence along the axial direction to form a complete annular flow channel system, so that the oil can flow from the first annular cavity 206 to the second annular cavity 208 through the third annular cavity 207, thereby realizing the directional flow of the oil.

[0039] The annular cavity is used to form an annular flow field when the oil flows through the dielectric spectrum sensor 20, so as to ensure that the oil is in full contact with the measuring electrode, thereby improving the uniformity and accuracy of the measurement. At the same time, the annular flow field can also reduce the flow resistance of the oil in the dielectric spectrum sensor 20, and reduce the impact on the oil pressure in the shunt detection branch.

[0040] The housing 201 is configured as an outer and inner split structure, which facilitates cleaning and replacement of the measuring electrodes of the dielectric spectrum sensor 20 during the installation and maintenance of the detection unit. In particular, under high temperature and high pressure conditions, impurities in the oil easily form sludge and carbide deposits on the surface of the measuring electrode, and these deposits change the electric field distribution characteristics of the surface of the measuring electrode. By configuring the housing 201 as an outer and inner split structure, maintenance personnel can regularly disassemble the outer housing 2011 to directly remove the deposits on the surface of the measuring electrode, thereby avoiding the influence of the deposits on the measurement accuracy.

[0041] Setting the shell 201 as an outer and inner split structure also facilitates adjustment of the coaxiality between the inner electrode 204 and the outer electrode 203. In a strong vibration environment, the measuring electrode is easily deformed, resulting in deviation of the coaxiality between the inner electrode 204 and the outer electrode 203, affecting the uniformity of the electric field distribution. By setting the shell 201 as an outer and inner split structure, the inner electrode 204 and the outer electrode 203 can be accurately aligned by adjusting the position of the outer shell 2011 during installation, and the coaxiality of the outer and inner shells can be regularly checked and calibrated during use to ensure that the measuring electrode and the measuring pipe section 10 remain coaxial, thereby improving the accuracy of dielectric spectrum measurement.

[0042] The outer shell 2011 includes an outer shell body and an inner shell wall, the outer shell body is cylindrical, and the inner shell wall is stepped. The inner shell wall includes a first inner wall segment, a second inner wall segment, and a third inner wall segment, which are arranged in sequence along the axial direction. The inner diameter of the first inner wall segment is larger than the inner diameter of the second inner wall segment, and the inner diameter of the second inner wall segment is larger than the inner diameter of the third inner wall segment, and an annular step surface is formed between adjacent inner wall segments.

[0043] The inner shell 2012 includes an inner shell body and an inner shell outer wall, the inner shell body is cylindrical, and the inner shell outer wall is stepped. The inner shell outer wall includes a fourth outer wall segment, a fifth outer wall segment, and a sixth outer wall segment, which are sequentially arranged along the axial direction. The outer diameter of the fourth outer wall segment is smaller than the outer diameter of the fifth outer wall segment, and the outer diameter of the fifth outer wall segment is smaller than the outer diameter of the sixth outer wall segment, and an annular step surface is formed between adjacent outer wall segments.

[0044] The outer shell 2011 and the inner shell 2012 are coaxially positioned by a detachable positioning assembly. The positioning assembly includes a positioning groove and a positioning block 205. The positioning groove is arranged on the inner wall of the outer shell 2011, and the positioning block 205 is arranged on the outer wall of the inner shell 2012.

[0045] A plurality of positioning grooves are provided along the circumference of the outer shell 2011, and the plurality of positioning grooves are evenly distributed along the circumference. Each positioning groove includes a mounting portion and a limiting portion, the mounting portion extends in the axial direction, and the limiting portion extends in the circumferential direction. One end of the mounting portion is connected to the end surface of the outer shell 2011, and the other end is connected to one end of the limiting portion. The width of the mounting portion is greater than the width of the limiting portion, and a step surface is formed at the connection between the mounting portion and the limiting portion.

[0046] The number of positioning blocks 205 is the same as the number of positioning slots, and the positioning blocks 205 correspond to the positioning slots one by one. Each positioning block 205 includes a sliding portion and a clamping portion, the sliding portion extends in the axial direction, and the clamping portion extends in the circumferential direction. One end of the sliding portion is fixedly connected to the outer wall of the inner shell 2012, and the other end is fixedly connected to one end of the clamping portion. The width of the sliding portion matches the width of the mounting portion, and the width of the clamping portion matches the width of the limiting portion.

[0047] The oil inlet is connected to the first annular cavity 206, and the oil outlet is connected to the second annular cavity 208, so that the oil can enter the first annular cavity 206 from the oil inlet, flow into the second annular cavity 208 through the third annular cavity 207, and finally flow out from the oil outlet.

[0048] An oil inlet passage is provided between the oil inlet and the first annular cavity 206, and the oil inlet passage includes a first oil inlet section and a second oil inlet section. The first oil inlet section extends in the axial direction, and the second oil inlet section extends in the radial direction. One end of the first oil inlet section is connected to the oil inlet, and the other end is connected to one end of the second oil inlet section, and the other end of the second oil inlet section is connected to the first annular cavity 206. An oil outlet passage is provided between the oil outlet and the second annular cavity 208, and the oil outlet passage includes a first oil outlet section and a second oil outlet section. The first oil outlet section extends in the axial direction, and the second oil outlet section extends in the radial direction. One end of the first oil outlet section is connected to the oil outlet, and the other end is connected to one end of the second oil outlet section, and the other end of the second oil outlet section is connected to the second annular cavity 208.

[0049] The first annular cavity 206 includes a first annular segment and a second annular segment, and the first annular segment and the second annular segment are arranged in sequence along the axial direction. The cross-sectional area of ​​the first annular segment is greater than the cross-sectional area of ​​the second annular segment, and a first step surface is formed between the first annular segment and the second annular segment. The axial length of the first annular segment is greater than the axial length of the second annular segment. A plurality of guide grooves are provided on the inner wall surface of the first annular segment, and the plurality of guide grooves are evenly distributed along the circumferential direction, and each guide groove extends along a spiral line. A diffuser is provided at the connection between the second oil inlet section and the first annular segment, and the diffuser includes a plurality of diffusion channels, and the plurality of diffusion channels are evenly distributed along the circumferential direction. The inlet end of each diffusion channel is connected to the second oil inlet section, and the outlet end is connected to the corresponding guide groove. The cross-sectional area of ​​the diffusion channel gradually increases from the inlet end to the outlet end, so that the oil can be evenly distributed when entering the first annular segment.

[0050] The second annular cavity 208 includes a third annular segment and a fourth annular segment, which are arranged in sequence along the axial direction. The cross-sectional area of ​​the third annular segment is smaller than the cross-sectional area of ​​the fourth annular segment, and a second step surface is formed between the third annular segment and the fourth annular segment. The axial length of the fourth annular segment is greater than the axial length of the third annular segment. A plurality of confluence grooves are provided on the inner wall surface of the fourth annular segment, and the plurality of confluence grooves are evenly distributed along the circumferential direction, and each confluence groove extends along a spiral line. A contraction structure is provided at the connection between the second oil outlet section and the fourth annular segment, and the contraction structure includes a plurality of contraction channels, and the plurality of contraction channels are evenly distributed along the circumferential direction. The inlet end of each contraction channel is connected to the corresponding confluence groove, and the outlet end is connected to the second oil outlet section. The cross-sectional area of ​​the contraction channel gradually decreases from the inlet end to the outlet end, so that the oil can be stably collected when entering the second oil outlet section.

[0051] The cross-sectional area of ​​the third annular cavity 207 gradually decreases along the axial direction, so that the oil gradually accelerates when flowing through the third annular cavity 207. The inner wall surface and the outer wall surface of the third annular cavity 207 are both tapered, and the taper of the inner wall surface and the outer wall surface is the same, ensuring that the cross-sectional shape of the third annular cavity 207 always remains annular. A first transition surface is provided at the connection between the third annular cavity 207 and the second annular segment. The first transition surface is in an arc shape, which is used to allow the oil to flow smoothly from the second annular segment into the third annular cavity 207. A second transition surface is provided at the connection between the third annular cavity 207 and the third annular segment. The second transition surface is in an arc shape, which is used to allow the oil to flow smoothly from the third annular cavity 207 into the third annular segment.

[0052] After the oil enters the oil inlet, it flows into the diffuser through the first oil inlet section and the second oil inlet section in turn. After being evenly dispersed in the diffuser, it enters the multiple guide grooves of the first annular section, flows along the spiral line under the guidance of the guide groove, and decelerates in the first annular section. The decelerated oil enters the second annular section, and then flows smoothly into the third annular cavity 207 through the first transition surface. The oil gradually accelerates in the third annular cavity 207, and flows smoothly into the third annular section through the second transition surface. The oil continues to accelerate in the third annular section and then enters the fourth annular section, flows along the spiral line of the confluence groove in the fourth annular section, and finally flows out of the oil outlet through the second oil outlet section and the first oil outlet section in turn after being converged by the contraction structure. Through the arrangement of the above structure, the oil forms a stable laminar flow state in the process of flowing through the dielectric spectrum sensor 20, thereby improving the measurement accuracy.

[0053] In the above technical solution, the guide groove and the confluence groove extend along the spiral line, which significantly increases the flow path length of the oil compared to the straight groove. The extended flow path gives the oil more time to complete speed adjustment and flow state conversion, which is conducive to forming a stable laminar flow state, and can also promote the uniform distribution of the oil and avoid local flow speed being too fast or too slow.

[0054] In addition, the spiral flow channel has a stabilizing effect similar to that of a gyroscope. When a local flow disturbance occurs, the centrifugal force generated by the spiral motion can quickly suppress the disturbance and return the fluid to a stable state. This helps maintain the stability of the measurement environment.

[0055] The measuring unit is arranged in the third annular cavity 207, and its core component is a pair of coaxial cylindrical measuring electrodes.

[0056] The measuring unit includes an inner electrode 204 and an outer electrode 203, and the inner electrode 204 and the outer electrode 203 are coaxially arranged in the third annular cavity 207. The inner electrode 204 includes an inner electrode body and an inner electrode support frame.

[0057] The inner electrode body is cylindrical, with its outer surface being the measuring surface and the interior being hollow. The upper and lower ends of the inner electrode body are respectively provided with annular flanges, which extend inward to form a support member, and the support member contacts the surface of the inner shell 2012. The inner electrode support frame includes a support arm, which is connected to the inner electrode body and the inner shell 2012.

[0058] The outer electrode 203 includes an outer electrode body and an outer electrode support frame. The outer electrode body is cylindrical, and its inner surface is a measuring surface. The outer electrode support frame includes a support ring, which is connected to the outer electrode body and the outer shell 2011. The inner electrode body and the outer electrode body are coaxially arranged, and an annular measuring area is formed between the two. The measuring area is coaxially arranged with the third annular cavity 207, so that when the oil flows through the measuring area, the two electrodes can monitor the oil quality by measuring the dielectric properties of the oil.

[0059] The inner electrode support frame and the outer electrode support frame are elastic support structures made of elastic materials to absorb external vibrations while maintaining the relative position of the electrodes. The inner electrode body and the outer electrode body are respectively connected to the signal line through conductive connectors, and the signal line is led to the signal processing unit 202 through the preset routing channels on the inner shell 2012 and the outer shell 2011.

[0060] The signal processing unit 202 includes an excitation signal generator, a signal collector and a signal conditioning circuit. The excitation signal generator is used to generate excitation signals of different frequencies, which are applied to the oil through the inner electrode 204. The signal collector is used to collect the response signal detected by the outer electrode 203. The signal conditioning circuit is used to amplify and filter the response signal.

[0061] The excitation signal generator uses direct digital frequency synthesis technology to generate a sine wave signal with a frequency range of 1Hz to 10MHz, a frequency resolution better than 0.1Hz, and an amplitude stability better than 0.1%. The excitation signal is applied between the inner electrode and the outer electrode to form an alternating electric field in the measurement area. The signal collector uses a 24-bit high-precision analog-to-digital converter with a sampling rate of 1MSPS. The input end of the analog-to-digital converter is equipped with a low-noise operational amplifier and a programmable gain amplifier to adaptively amplify response signals of different frequencies and amplitudes. The signal collector is used to measure the voltage, current amplitude and phase at different frequencies. The signal conditioning circuit includes a preamplifier, a bandpass filter and a programmable gain amplifier. The preamplifier uses a low-noise instrumentation amplifier with an input impedance greater than 10GΩ and a common mode rejection ratio greater than 100dB. The bandpass filter uses a switched capacitor filter, and its center frequency and bandwidth are dynamically adjusted according to the frequency of the excitation signal. The gain of the programmable gain amplifier is adjusted in 0.1dB steps from 0dB to 60dB. The signal conditioning circuit is used to measure the phase difference between voltage and current and calculate the real and imaginary parts of the complex dielectric constant of the oil based on the sampled data.

[0062] During the measurement process, the alternating electric field generated by the excitation signal generator causes the polar molecules in the oil to be oriented and polarized. Due to the inertia of molecular motion and the influence of viscous resistance, the polarization process lags behind the external electric field. This lag phenomenon leads to the frequency dependence of the complex dielectric constant. The complex dielectric constant is measured at different frequencies, and its change relationship with frequency is plotted into a curve, which is the dielectric spectrum of the oil.

[0063] In order to accurately obtain the dielectric spectrum, the signal processing unit 202 performs precise measurements of the amplitude and phase at each measurement frequency point. By measuring the amplitude ratio |Z|=|U| / |I| and the phase difference φ of the voltage U applied to the oil and the current I flowing through the oil, the complex dielectric constant can be calculated:

[0064] ε' = |Z|cosφ / (ωC0)

[0065] ε" = |Z|sinφ / (ωC0)

[0066] Among them, ω is the angular frequency and C0 is the vacuum capacitance. This measurement method can simultaneously obtain the real and imaginary parts of the complex dielectric constant and fully characterize the dielectric properties of the oil.

[0067] In practical applications, multiple measurement points can be selected within a preset frequency range (1Hz-10MHz), and a set of complex dielectric constant data can be obtained at each measurement point. These data points constitute the dielectric spectrum curve of the oil, which is used to evaluate the quality status of the oil. By comparing with the dielectric spectrum of the standard oil, it can be determined whether the oil has deteriorated, providing a basis for equipment maintenance.

[0068] To improve the measurement accuracy and shorten the response time, as an improvement, Figure 4 As shown, a plurality of micro grooves 2041 are respectively provided on the outer surface of the inner electrode body and the inner surface of the outer electrode body, and the plurality of micro grooves 2041 are evenly distributed along the circumference and extend in a spiral shape. The cross section of each micro groove 2041 is V-shaped, and the opening width of the V-shaped groove is smaller than the groove depth, so that the oil forms a stable micro eddy current when flowing through the micro groove 2041. This micro eddy current can capture tiny particles in the oil and prevent the particles from accumulating on the electrode surface. At the same time, it can also increase the contact area between the oil and the electrode surface, thereby improving the measurement sensitivity.

[0069] The inner surface of the micro groove 2041 is provided with a plurality of guide protrusions, each of which has a triangular cross section and a height less than one quarter of the gap between the inner and outer electrodes. The guide protrusions are used to enhance the disturbance effect of the oil to form the micro vortex.

[0070] In order to solve the problem of unstable electrode position of the dielectric spectrum sensor 20 in a vibration environment, the present application adopts an elastic support structure to support the inner electrode 204 and the outer electrode 203. The inner electrode support frame and the outer electrode support frame are both made of elastic metal materials to form an elastic support structure. The elastic support structure can absorb external vibration while maintaining the relative position of the electrodes stable, effectively reducing the impact of vibration on measurement accuracy.

[0071] In order to solve the problem that sludge and carbide deposits are easily formed on the electrode surface, the present application sets a micro groove 2041 on the electrode measuring surface. The micro eddy current in the micro groove 2041 can carry away the deposits in time, and sets an anti-deposition coating on the surface of the micro groove 2041. The coating is made of nano-scale fluorocarbon material. The coating has extremely low surface energy and can effectively prevent the adhesion of impurity particles in the oil without affecting the conductive properties of the electrode.

[0072] When the oil flows at high speed or the pressure changes suddenly, a bubble layer is easily formed on the electrode surface. These bubbles will significantly change the dielectric properties of the measuring area, causing large fluctuations in the measurement results.

[0073] To solve this problem, a bubble separator is provided at the inlet end of the third annular cavity 207. The bubble separator includes a separation chamber and a plurality of flow guide pipes. The separation chamber is annular and is provided at the inlet of the third annular cavity 207. The inner wall and the outer wall of the separation chamber are both cylindrical, and the top wall is annular. The plurality of flow guide pipes are evenly distributed along the circumference of the separation chamber, and the outlet end of each flow guide pipe forms a preset angle with the tangential direction of the separation chamber.

[0074] Each guide tube includes an inlet section, a middle section and an outlet section. The inlet section is trumpet-shaped and is used to collect oil. The cross-sectional area of ​​the middle section is smaller than that of the inlet section, which is used to increase the flow rate of the oil. The cross-sectional area of ​​the outlet section gradually increases, and the outlet end deflects tangentially to form a rotating flow field.

[0075] A plurality of exhaust holes are arranged on the top wall of the separation chamber, each of which is connected to an exhaust pipe, which extends upward and is connected to the gas collecting tank. A vent valve is arranged on the top of the gas collecting tank to discharge the collected gas regularly.

[0076] A plurality of guide vanes are arranged at the bottom of the separation chamber, and the guide vanes are evenly distributed along the circumference. Each guide vane is arc-shaped, and its arc surface is adapted to the direction of the rotating flow field. The guide vanes are used to maintain the stability of the rotating flow field and avoid flow field turbulence.

[0077] When the oil enters the guide tube, it gathers at the inlet section, accelerates through the middle section, and is ejected from the outlet section at high speed into the separation chamber. Due to the tangential setting of the outlet section, the oil forms a strong rotating flow field in the separation chamber. Under the action of centrifugal force, the oil with higher density is thrown to the outer wall of the separation chamber, while the bubbles with lower density gather toward the center of the separation chamber. The gathered bubbles rise under the action of buoyancy, enter the exhaust pipe through the exhaust hole, and are finally collected in the gas collecting tank.

[0078] Under the guidance of the guide vanes, the oil separated by bubbles maintains a rotating flow state and enters the third annular cavity 207, ensuring the uniformity and stability of the oil in the measurement area. Through the synergistic effect of multiple guide tubes, a rotating flow field with uniform intensity is formed, which improves the bubble separation effect.

[0079] In the actual working environment, external electromagnetic fields (such as high-voltage motors, frequency converters, etc.) will interfere with the measurement signal of the electrode and reduce the measurement accuracy.

[0080] To solve this problem, an electromagnetic shielding assembly is provided outside the dielectric spectrum sensor 20. The electromagnetic shielding assembly includes a shielding outer cylinder, a shielding inner cylinder and an end shielding member.

[0081] The shielding outer cylinder is detachably connected to the outer shell 2011 of the shell 201. The shielding outer cylinder is cylindrical, and its inner diameter is larger than the outer diameter of the dielectric spectrum sensor 20, forming an annular cavity. The shielding outer cylinder includes an outer metal mesh and an inner magnetic layer, the outer metal mesh is located on the outside, and the inner magnetic layer is located on the inside. The outer metal mesh is woven from conductive metal wires and is used to shield the external electric field. The inner magnetic layer is cylindrical and is used to shield the external magnetic field. The two ends of the shielding outer cylinder are provided with a first connecting flange, and the first connecting flange is fixedly connected to the outer shell 2011 of the shell 201.

[0082] The shielding inner cylinder is detachably connected to the inner shell 2012 of the shell 201. The shielding inner cylinder includes a first metal mesh layer and a first magnetic layer, the first metal mesh layer is located on the outside, and the first magnetic layer is located on the inside. Second connection flanges are provided at both ends of the shielding inner cylinder, and the second connection flanges are connected to the inner shell 2012 through fasteners. A plurality of first grounding terminals are provided on the second connection flanges, and the plurality of first grounding terminals are evenly distributed along the circumference. Each first grounding terminal is electrically connected to the first metal mesh layer, and is connected to the ground wire through an independent first grounding wire.

[0083] When the measuring electrode of the dielectric spectrum sensor 20 needs to be cleaned or replaced, the inner housing 2012 can be separated from the outer housing 2011, and the shielding inner cylinder is removed together with the inner housing 2012, while the shielding outer cylinder remains connected to the outer housing 2011. This split design ensures the electromagnetic shielding effect without affecting the maintenance operation of the dielectric spectrum sensor 20.

[0084] The end shielding parts are arranged at both ends of the shielding outer cylinder for electromagnetic shielding of the ends. The end shielding parts include a shielding ring plate and a shielding end cover. The shielding ring plate is in a circular ring shape, and its inner circle cooperates with the signal interface of the dielectric spectrum sensor 20, and its outer circle cooperates with the end face of the shielding outer cylinder. The shielding end cover is arranged on the outer side of the shielding ring plate, and includes a second metal mesh layer and a second magnetic layer. A cable channel is provided on the end shielding part for passing the signal line and the power line. A cable shielding sleeve is provided in the cable channel, and the cable shielding sleeve includes an inner insulating layer and an outer metal mesh layer.

[0085] In order to further improve the shielding effect, a signal shielding component is arranged outside the signal transmission cable. The signal shielding component includes a braided metal mesh and a magnetic shielding sleeve. The braided metal mesh is coated on the outside of the signal line, and the magnetic shielding sleeve is arranged on the outside of the braided metal mesh. One end of the braided metal mesh is connected to the grounding ring at the end of the dielectric spectrum sensor 20, and the other end is connected to the grounding end of the signal processing unit 202. Both ends of the magnetic shielding sleeve are provided with a second grounding terminal, and are connected to the ground wire through an independent second grounding wire.

[0086] The above-mentioned electromagnetic shielding assembly can effectively shield the interference of the external electromagnetic field on the dielectric spectrum sensor 20. The shielding outer cylinder and the shielding inner cylinder form a double-layer shielding, in which the metal mesh layer shields the electric field interference and the magnetic layer shields the magnetic field interference, thereby ensuring the overall shielding effect of the dielectric spectrum sensor 20.

[0087] This solution can block the external electromagnetic field at the source and prevent the electromagnetic field from entering the dielectric spectrum sensor 20 to interfere with the electrodes, while not affecting the maintenance operation of the dielectric spectrum sensor 20 by providing a split shielding component outside the dielectric spectrum sensor 20 .

[0088] In the actual working environment, the oil temperature may rise from room temperature to over 200°C. The temperature change will cause different degrees of thermal expansion of the inner and outer electrodes, change the electrode spacing, and thus affect the measurement accuracy.

[0089] In order to solve the problem that the temperature change of oil causes different degrees of thermal expansion of the inner and outer electrodes, which affects the measurement accuracy, multiple telescopic shells and multiple compensation components are arranged between the inner electrode body and the outer electrode body. The telescopic shell is arranged between the inner electrode body and the outer electrode body, and the compensation component is arranged inside the telescopic shell. The multiple telescopic shells and multiple compensation components are evenly distributed along the circumference.

[0090] The telescopic shell includes a first shell and a second shell. The first shell is fixed on the outer surface of the inner electrode body, and the second shell is fixed on the inner surface of the outer electrode body. The first shell and the second shell are both cylindrical and made of elastic materials. The outer surface of the first shell and the inner surface of the second shell are both designed as streamlined surfaces to reduce the impact on the flow of oil. The ends of the first shell and the second shell are connected by a bellows, which can be expanded and contracted in the radial direction so that the first shell and the second shell can move relative to each other. The inner and outer surfaces of the bellows are both designed as streamlined surfaces to avoid turbulence. The telescopic shell isolates the compensation component from the oil to prevent the compensation component from affecting the flow state of the oil.

[0091] Since the compensation component is arranged in the telescopic shell, the oil does not directly contact the compensation component, so turbulence and bubbles will not be generated.

[0092] Each compensation assembly includes a support seat, a push block and a temperature control spring. The support seat is fixed on the outer surface of the inner electrode body and includes a substrate and a guide plate. The substrate is rectangular, and one end of the substrate is fixedly connected to the outer surface of the inner electrode body. The guide plate is vertically arranged at the end of the substrate away from the inner electrode body, and a guide through hole is provided on the guide plate. The guide through hole extends radially, and its cross section is circular. Limit blocks are respectively provided on both sides of the guide plate, and the two limit blocks are respectively located at the two ends of the guide through hole.

[0093] The push block includes a push rod and a contact head. The push rod is cylindrical, and its diameter is adapted to the inner diameter of the guide through hole. The push rod is inserted into the guide through hole and can slide back and forth along the axial direction of the guide through hole. The inner end of the push rod is provided with a first limit step, and the outer end is provided with a second limit step. The first limit step cooperates with the limit block on the inner side of the guide plate, and the second limit step cooperates with the limit block on the outer side of the guide plate. The cooperation between the two limit steps and the limit block limits the sliding stroke of the push rod. The contact head is fixed to the outer end of the push rod and is hemispherical, and its spherical surface is in tangential contact with the inner surface of the outer electrode body. The surface of the contact head is polished to reduce the friction with the inner surface of the outer electrode body.

[0094] The temperature control spring is sleeved on the push rod and is located on the inner side of the guide plate. The inner end of the temperature control spring abuts against the first limit step, and the outer end abuts against the inner surface of the guide plate. The temperature control spring is made of temperature-sensitive material, and the elastic modulus of the material increases with increasing temperature. That is, when the temperature increases, the elastic force of the temperature control spring increases; when the temperature decreases, the elastic force of the temperature control spring decreases.

[0095] When the oil temperature rises, both the inner electrode body and the outer electrode body undergo thermal expansion. Due to the different thermal expansion coefficients of the two, the electrode spacing changes. At this time, the elastic force of the temperature control spring increases with the temperature increase, pushing the push block outward. The push block applies radial force to the outer electrode body through the contact head, keeping the outer electrode body in the predetermined position, thereby maintaining the stability of the electrode spacing.

[0096] When the oil temperature drops, both the inner electrode body and the outer electrode body shrink, and the electrode spacing changes. At this time, the elastic force of the temperature control spring decreases as the temperature drops. Under the action of the elastic force of the outer electrode body itself, the push block moves inward, so that the outer electrode body returns to the predetermined position.

[0097] The arrangement of multiple compensation components evenly distributed along the circumference ensures uniform support force on the outer electrode body and avoids local deformation. The cooperation between the guide through hole and the push rod ensures the stability of the radial movement of the push block. The setting of the limit structure prevents excessive displacement of the push block. The spherical design of the contact head reduces the contact stress with the outer electrode body and avoids wear. The characteristic design of the temperature control spring realizes the adaptive matching of compensation force and temperature.

[0098] Through the above-mentioned compensation component, the inner and outer electrode bodies can actively adapt to changes in oil temperature, automatically adjust the distance between the inner and outer electrodes, and maintain measurement accuracy.

[0099] The dielectric spectrum sensor provided in this application realizes fast and accurate online measurement of the dielectric spectrum of oil through the following technical solutions:

[0100] First, the present application forms an annular cavity including a first annular cavity 206, a third annular cavity 207 and a second annular cavity 208 between the outer shell 2011 and the inner shell 2012, and sets a guide groove extending along the spiral line in the first annular cavity 206, and sets a confluence groove extending along the spiral line in the second annular cavity 208, thereby forming a unique flow field control structure, so that the oil forms a stable spiral flow field when flowing through the sensor. When local flow disturbance occurs, the centrifugal force generated by the spiral motion can quickly suppress the disturbance and return the fluid to a stable state. At the same time, the spiral flow field extends the flow path of the oil in the sensor, so that the oil has more time to complete speed adjustment and flow state conversion, ensuring that the oil is in full contact with the measuring electrode, thereby improving the measurement accuracy.

[0101] Secondly, the present application sets the measuring unit in the third annular cavity 207, and sets the inner electrode 204 and the outer electrode 203 coaxially. Since the third annular cavity 207 is located between the first annular cavity 206 and the second annular cavity 208, the oil flowing through the area has completed the initial speed adjustment and flow state conversion, and is in the most stable flow state, ensuring the uniformity of the oil in the measuring area and significantly improving the measurement accuracy. At the same time, the coaxial setting of the inner electrode 204 and the outer electrode 203 ensures the formation of a uniform electric field distribution between the measuring electrodes, avoiding the influence of local electric field distortion on the measurement results.

[0102] The embodiments of the present application are described in detail above, and the contents of this specification should not be construed as limiting the scope of protection of the present application.

Claims

1. A dielectric spectrum sensor for online monitoring of oil quality, characterized in that: include: A shell, the shell comprising an outer shell and an inner shell, an annular cavity is formed between the outer shell and the inner shell, the annular cavity comprises a first annular cavity, a second annular cavity and a third annular cavity, the first annular cavity, the third annular cavity and the second annular cavity are sequentially arranged along the axial direction, a guide groove is provided in the first annular cavity, a confluence groove is provided in the second annular cavity, and the guide groove and the confluence groove both extend along a spiral line; as well as A measuring unit, the measuring unit is arranged in the third annular cavity, the measuring unit comprises an inner electrode assembly and an outer electrode assembly, the inner electrode assembly and the outer electrode assembly are coaxially arranged, the inner electrode assembly comprises an inner electrode body, the outer electrode assembly comprises an outer electrode body, a plurality of grooves are respectively arranged on the outer surface of the inner electrode body and the inner surface of the outer electrode body, the plurality of grooves are uniformly distributed along the circumferential direction and extend in a spiral shape; Among them, the cross-sectional area of ​​the third annular cavity gradually decreases along the axial direction, the inner wall surface and the outer wall surface of the third annular cavity are both conical, the tapers of the inner wall surface and the outer wall surface are the same, and a first arc-shaped transition surface is provided at the connection between the third annular cavity and the first annular cavity, and a second arc-shaped transition surface is provided at the connection between the third annular cavity and the second annular cavity.

2. The dielectric spectrum sensor according to claim 1, characterized in that: The first annular cavity includes a first annular segment and a second annular segment arranged in sequence along the axial direction, the cross-sectional area of ​​the first annular segment is greater than the cross-sectional area of ​​the second annular segment, a first step surface is formed between the first annular segment and the second annular segment, the axial length of the first annular segment is greater than the axial length of the second annular segment, the guide groove is arranged on the inner wall surface of the first annular segment, and the plurality of guide grooves are evenly distributed along the circumferential direction.

3. The dielectric spectrum sensor according to claim 2, characterized in that: The second annular cavity includes a third annular segment and a fourth annular segment which are arranged in sequence along the axial direction, the cross-sectional area of ​​the third annular segment is smaller than the cross-sectional area of ​​the fourth annular segment, a second step surface is formed between the third annular segment and the fourth annular segment, the axial length of the fourth annular segment is greater than the axial length of the third annular segment, the confluence groove is arranged on the inner wall surface of the fourth annular segment, and a plurality of the confluence grooves are evenly distributed along the circumferential direction.

4. The dielectric spectrum sensor according to claim 3, characterized in that: It also includes an oil inlet channel and an oil outlet channel, the oil inlet channel includes a first oil inlet section and a second oil inlet section, the first oil inlet section extends axially, the second oil inlet section extends radially, one end of the first oil inlet section is connected to the oil inlet, and the other end is connected to one end of the second oil inlet section, and the other end of the second oil inlet section is connected to the first annular cavity, the oil outlet channel includes a first oil outlet section and a second oil outlet section, the first oil outlet section extends axially, the second oil outlet section extends radially, one end of the first oil outlet section is connected to the oil outlet, and the other end is connected to one end of the second oil outlet section, and the other end of the second oil outlet section is connected to the second annular cavity.

5. The dielectric spectrum sensor according to claim 4, characterized in that: A diffuser is provided at the connection between the second oil inlet section and the first annular section, and the diffuser includes a plurality of diffuser channels, and the plurality of diffuser channels are evenly distributed along the circumferential direction. The inlet end of each diffuser channel is connected to the second oil inlet section, and the outlet end is connected to the corresponding guide groove, and the cross-sectional area of ​​the diffuser channel gradually increases from the inlet end to the outlet end; a contraction structure is provided at the connection between the second oil outlet section and the fourth annular section, and the contraction structure includes a plurality of contraction channels, and the plurality of contraction channels are evenly distributed along the circumferential direction. The inlet end of each contraction channel is connected to the corresponding confluence groove, and the outlet end is connected to the second oil outlet section, and the cross-sectional area of ​​the contraction channel gradually decreases from the inlet end to the outlet end.

6. The dielectric spectrum sensor according to claim 1, characterized in that: The outer shell and the inner shell are coaxially positioned by a detachable positioning assembly, the positioning assembly includes a plurality of positioning grooves and a plurality of positioning blocks, the plurality of positioning grooves are evenly distributed along the circumference of the outer shell, the plurality of positioning blocks correspond to the plurality of positioning grooves one by one, each of the positioning grooves includes a mounting portion and a limiting portion, the mounting portion extends in the axial direction, the limiting portion extends in the circumferential direction, each of the positioning blocks includes a sliding portion and a clamping portion, the sliding portion extends in the axial direction, and the clamping portion extends in the circumferential direction.

7. The dielectric spectrum sensor according to claim 1, characterized in that: The inner electrode body is cylindrical, and the outer surface of the inner electrode body is a measuring surface; The inner electrode assembly further comprises: The inner electrode support frame comprises a support arm, and the support arm is connected to the inner electrode body and the inner shell.

8. The dielectric spectrum sensor according to claim 1, characterized in that: The outer electrode body is cylindrical, and the inner surface of the outer electrode body is a measuring surface; The outer electrode assembly further comprises: The outer electrode support frame comprises a support ring, and the support ring is connected to the outer electrode body and the outer shell.

9. The dielectric spectrum sensor according to claim 7 or 8, characterized in that: The inner electrode support frame and the outer electrode support frame are both made of elastic material.

Images