A method and system for measuring the viscosity of a liquid by vibration

Abstract

The application relates to a kind of vibration type liquid viscosity measurement method and system, wherein, method is: first, the reference resonant frequency, first resonant frequency and second resonant frequency of target liquid are acquired, wherein, the frequency of the vibration signal generated by resonant sensitive element under the excitation of excitation signal with reference signal same frequency same phase is reference resonant frequency;The frequency of the vibration signal generated by resonant sensitive element under the excitation of excitation signal with reference resonant frequency same frequency but phase ahead or lag reference excitation signal setting angle is first, second resonant frequency;Then, the frequency offset of first resonant frequency and second resonant frequency is determined, and the viscosity of target liquid is determined according to reference resonant frequency, frequency offset and viscosity-frequency calibration relationship.This application calculates the viscosity of liquid by obtaining the resonant frequency and the offset of resonant frequency of system, and the measuring process is simple and practical.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of liquid viscosity measurement, and particularly relates to a vibrating liquid viscosity measurement method and system. BACKGROUND

[0002] Viscosity is an important physical property parameter of a liquid, and can be used to reflect the viscosity of the liquid. Liquid viscosity measurement has very important significance in the fields of petroleum, chemical industry, biomedicine and energy, and is an important means for controlling production processes, improving product yield, realizing safe and efficient production and saving energy. At present, as common methods for online measurement of liquid viscosity, the vibrating method and the piezoelectric resonance method both use vibrating sensors, and the sensitive element as the core part of the sensor determines the performance parameters of the sensor.

[0003] Currently, common online measurement methods include the optical fiber method, the vibrating method, the ultrasonic method and the piezoelectric resonance method. For the vibrating method, the existing vibrating measurement method has a complex measurement process and poor practicability. SUMMARY

[0004] The present application aims to provide a liquid viscosity measurement system and method with a simple measurement process.

[0005] To achieve the above object, the present application provides the following solutions.

[0006] A vibrating liquid viscosity measurement method comprises the following steps:

[0007] Step 1: obtaining a reference resonance frequency, a first resonance frequency and a second resonance frequency of a target liquid;

[0008] The reference resonance frequency is the frequency of a pick-up signal of a resonance sensitive element when the phase difference between the pick-up signal and a reference signal is 90° in the target liquid; the pick-up signal is a vibration signal generated by the resonance sensitive element under the excitation of an excitation signal with the same frequency and phase as the reference signal;

[0009] The first resonance frequency is the frequency of a first pick-up signal of a resonance sensitive element when the phase difference between the first pick-up signal and a reference signal is 90° in the target liquid; the first pick-up signal is a vibration signal generated by the resonance sensitive element under the excitation of a first excitation signal; the frequency of the first excitation signal is the reference resonance frequency, and the phase of the first excitation signal leads the reference excitation signal by a first set angle;

[0010] The second resonance frequency is the frequency of the second pick-up signal of the resonance sensitive element in the target liquid when the phase difference between the second pick-up signal and the reference signal is 90°; the second pick-up signal is the vibration signal generated by the resonance sensitive element under the excitation of the second excitation signal; the frequency of the second excitation signal is the reference resonance frequency, and the second excitation signal lags behind the reference excitation signal by a second set angle; the second set angle of the second excitation signal is equal to the first set angle of the first excitation signal in size;

[0011] Step 2, determining the frequency offset of the first resonance frequency and the second resonance frequency;

[0012] Step 3, obtaining a viscosity-frequency calibration relationship;

[0013] Step 4, determining the viscosity of the target liquid according to the reference resonance frequency, the frequency offset, and the viscosity-frequency calibration relationship.

[0014] Optionally, step 4 specifically comprises:

[0015] According to calculating the viscosity η of the target liquid, wherein f is the resonance frequency of the sensor, Δf=f2-f1 is the offset of the resonance frequency, f1 is the first resonance frequency, f2 is the second resonance frequency, A, B, C are obtained through a viscosity-frequency calibration experiment.

[0016] The application also provides a vibration type liquid viscosity measurement system applied to the vibration type liquid viscosity measurement method, and the vibration type liquid viscosity measurement system comprises a resonance sensitive element, an adjustable frequency signal excitation module, a resonance detection module, and a signal processing module.

[0017] The resonance sensitive element is used to be placed in a target liquid.

[0018] The adjustable frequency signal excitation module is connected with the resonance sensitive element and is used to output an excitation signal with adjustable frequency to the resonance sensitive element.

[0019] The resonance detection module is connected with the resonance sensitive element and the adjustable frequency signal excitation module, is used to collect the vibration signal of the resonance sensitive element, and determine the phase difference between the vibration signal and the reference signal; the adjustable frequency signal excitation module is further used to adjust the frequency of the excitation signal when the phase difference is not 90°, until the phase difference is 90°.

[0020] The signal processing module is used to execute the vibration type liquid viscosity measurement method.

[0021] Optionally, the resonance sensitive element is a thin-walled cylindrical barrel.

[0022] Optionally, the adjustable frequency signal excitation module comprises an adjustable frequency signal generator and an excitation element.

[0023] The adjustable frequency signal generator is configured to generate an excitation signal and the reference signal.

[0024] The excitation element is connected to the resonance sensitive element and configured to provide excitation force to the resonance sensitive element under the action of the excitation signal.

[0025] Optionally, the resonance detection module comprises a phase-locked amplifier.

[0026] Optionally, the phase-locked amplifier comprises a signal channel, a reference channel, a phase-sensitive detector, and a low-pass filter; the signal channel is connected to the signal input end of the phase-sensitive detector; the reference channel is connected to the reference signal input end of the phase-sensitive detector; and the output end of the phase-sensitive detector is connected to the low-pass filter.

[0027] Optionally, the resonance detection module comprises a vibration pickup element configured to collect the vibration signal of the resonance sensitive element and transmit the vibration signal to the phase-locked amplifier.

[0028] Optionally, the signal processing module comprises an analog-to-digital converter.

[0029] The analog-to-digital converter is connected to the resonance detection module and configured to convert the vibration signal detected by the resonance detection module into a digital signal.

[0030] Optionally, the signal processing module comprises a microcontroller.

[0031] The microcontroller is configured to adjust the frequency output by the adjustable frequency signal excitation module according to the digital signal output by the analog-to-digital converter, and execute the vibration type liquid viscosity measurement method.

[0032] According to the specific embodiments provided in the present application, the following technical effects are disclosed: the present application provides a vibration type liquid viscosity measurement method and system. The measurement method comprises the following steps: firstly, obtaining the reference resonance frequency, the first resonance frequency and the second resonance frequency of the target liquid. The reference resonance frequency is the frequency of the pick-up signal of the resonance sensitive element when the phase difference between the pick-up signal and the reference signal is 90° in the target liquid. The pick-up signal is the vibration signal generated by the resonance sensitive element under the excitation of the excitation signal with the same frequency and phase as the reference signal. The first resonance frequency is the frequency of the first pick-up signal of the resonance sensitive element when the phase difference between the first pick-up signal and the reference signal is 90° in the target liquid. The first pick-up signal is the vibration signal generated by the resonance sensitive element under the excitation of the first excitation signal. The frequency of the first excitation signal is the reference resonance frequency, and the phase of the first excitation signal leads the reference excitation signal by a first set angle. The second resonance frequency is the frequency of the second pick-up signal of the resonance sensitive element when the phase difference between the second pick-up signal and the reference signal is 90° in the target liquid. The second pick-up signal is the vibration signal generated by the resonance sensitive element under the excitation of the second excitation signal. The frequency of the second excitation signal is the reference resonance frequency, and the phase of the second excitation signal lags the reference excitation signal by a second set angle. The second set angle of the second excitation signal is equal to the first set angle of the first excitation signal. Then, the frequency offset of the first resonance frequency and the second resonance frequency is determined. The viscosity of the target liquid is determined according to the reference resonance frequency, the frequency offset and the viscosity-frequency calibration relationship. According to the resonance frequency of the resonance sensitive element in the liquid and the resonance frequency offset, the viscosity of the liquid to be measured is calculated. Since the calculation target is single, the measurement process is relatively simple. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0034] Figure 1 The flow chart of the vibration type liquid viscosity measurement method provided in the present application;

[0035] Figure 2 The schematic diagram of the vibration type liquid viscosity measurement system provided in the present application;

[0036] Figure 3 The structural block diagram of the phase-locked amplifier provided in the present application;

[0037] Figure 4 The resonance characteristic curve diagram of different viscosity liquids provided in the present application. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] The purpose of this application is to provide a vibration-based liquid viscosity measurement method and system.

[0040] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] This application provides a vibration-based liquid viscosity measurement method:

[0042] Step 1: Obtain the reference resonant frequency, the first resonant frequency, and the second resonant frequency of the target liquid;

[0043] The reference resonant frequency is the frequency of the pickup signal when the phase difference between the pickup signal of the resonant sensitive element and the reference signal is 90° in the target liquid; the pickup signal is the vibration signal generated by the resonant sensitive element under the excitation of an excitation signal with the same frequency and phase as the reference signal.

[0044] The first resonant frequency is: the frequency of the first vibration signal when the phase difference between the first vibration signal of the resonant sensitive element and the reference signal is 90° in the target liquid; the first vibration signal is: the vibration signal generated by the resonant sensitive element under the excitation of the first excitation signal; the frequency of the first excitation signal is the reference resonant frequency, and the phase of the first excitation signal leads the reference excitation signal by a first set angle.

[0045] The second resonant frequency is: the frequency of the second vibration pickup signal when the phase difference between the second vibration pickup signal of the resonant sensitive element and the reference signal is 90° in the target liquid; the second vibration pickup signal is: the vibration signal generated by the resonant sensitive element under the excitation of the second excitation signal; the frequency of the second excitation signal is the reference resonant frequency, and the phase of the second excitation signal lags the reference excitation signal by a second set angle; the second set angle of the second excitation signal is equal in magnitude to the first set angle of the first excitation signal.

[0046] Step 2: Determine the frequency offset between the first resonant frequency and the second resonant frequency.

[0047] Step 3, obtain the viscosity-frequency calibration relationship.

[0048] Step 4, determine the viscosity of the target liquid according to the reference resonance frequency, the frequency offset, and the viscosity-frequency calibration relationship.

[0049] In some embodiments, in order to calculate the viscosity of the liquid, the damping coefficient of the system is also needed, which can be obtained according to the following method:

[0050] The resonant cylinder is equivalent to a viscous damping linear single degree of freedom vibration system, and the resonance characteristic curve of the resonant cylinder is as shown in Figure 2 At the same density, the amplitude-frequency characteristic curve of the resonant cylinder vibrating in a liquid with different viscosities is different, the liquid viscosity of the solid line representing the resonance characteristic curve is η1, and the liquid viscosity of the dashed line representing the resonance characteristic curve is η2, and η1> η2. For such a vibration system, two quantities can be used to describe, one is the resonance frequency of the system, that is, the above-mentioned reference resonance frequency f, which can be obtained by the same frequency and phase of the excitation signal and the reference signal, and the phase difference between the excitation signal and the pick-up signal is 90°. The first resonance frequency f1 is obtained by the excitation signal leading the reference signal by 45°, and the phase difference between the pick-up signal and the reference signal is 90°; the second resonance frequency f2 can be obtained by the excitation signal lagging the reference signal by 45°, and the phase difference between the pick-up signal and the reference signal is 90°. The other is the resonance system bandwidth Δf, which is a measure of the damping coefficient, and the difference between the frequencies measured at the two points of phase difference α of +45° and -45° is Δf, where α can also be arbitrarily specified, and the quality factor Q can be defined as The damping coefficient ζ can be represented as

[0051] In some embodiments, step 4 can specifically include:

[0052] According to Calculate the viscosity η of the target liquid, where f is the reference resonance frequency of the sensor, Δf = f2-f1 is the offset of the resonance frequency, f1 is the first resonance frequency, f2 is the second resonance frequency, A, B, and C are obtained through the viscosity-frequency calibration experiment.

[0053] In some embodiments, the specific implementation steps of measuring the viscosity of the liquid are as follows:

[0054] 1) Set the reference signal and the excitation signal to the same frequency and phase, and obtain the reference resonance frequency f using the resonance frequency determination method, at this time the phase difference between the excitation signal and the pick-up signal is 90°, and the method obtains the reference resonance frequency f.

[0055] 2) Set the reference signal and the excitation signal at the same frequency, and the phase of the excitation signal is 45° ahead of the phase of the reference signal (+45°), and the vibration frequency f2 is obtained by using the resonance frequency judgment method. When the phase difference detected by the lock-in amplifier is 90°, the output DC voltage signal is 0, but at this time the excitation signal is 45° ahead of the reference signal, so the obtained vibration frequency is the frequency that causes the phase difference between the excitation signal and the pick-up signal to be 135°, corresponding to f2 in the formula (1). Figure 2

[0056] 3) Set the reference signal and the excitation signal at the same frequency, and the phase of the excitation signal lags behind the phase of the reference signal by 45° (-45°), and the vibration frequency f1 is obtained by using the resonance frequency judgment method. The analysis method is the same as the above analysis method. At this time, the obtained vibration frequency is the frequency that causes the phase difference between the excitation signal and the pick-up signal to be 45°, corresponding to f1 in the formula (1). Figure 2

[0057] Calculate the shift of the resonance frequency Δf = f2 - f1, and combine the reference resonance frequency f obtained before, and calculate the viscosity of the liquid according to the formula

[0058] The application also provides a vibrating liquid viscosity measurement system, which is applied to the vibrating liquid viscosity measurement method, and the measurement system comprises a resonance sensitive element, an adjustable frequency signal excitation module, a resonance detection module and a signal processing module.

[0059] The resonance sensitive element is used to be placed in a target liquid.

[0060] The adjustable frequency signal excitation module is connected with the resonance sensitive element, and is used to output an excitation signal with adjustable frequency to the resonance sensitive element.

[0061] The resonance detection module is connected with the resonance sensitive element and the adjustable frequency signal excitation module, and is used to collect the vibration signal of the resonance sensitive element and determine the phase difference between the vibration signal and the reference signal. The adjustable frequency signal excitation module is also used to adjust the frequency of the excitation signal when the phase difference is not 90°, until the phase difference is 90°.

[0062] The signal processing module is used to execute the vibrating liquid viscosity measurement method.

[0063] In some embodiments, the resonance sensitive element is a thin-walled cylindrical barrel.

[0064] ​​​Specifically, in the vibration sensor, the basic principle of using a thin-walled cylindrical resonant cylinder as a sensitive element to measure the viscosity of a liquid is that the resonance frequency and damping coefficient of the resonant cylinder vibration system are affected by both the characteristics of the system itself and the external environment. Different viscosities of the measured liquid have different effects on the vibration of the resonant cylinder, which causes changes in the resonant characteristics of the resonant cylinder, and the resonance frequency and damping coefficient of the system also change. Thus, a relationship between the viscosity of the liquid and the resonance frequency and damping coefficient can be established.

[0065] In some embodiments, as shown in FIG. 1, the specific composition of the adjustable frequency signal excitation module, the resonant detection module, and the signal processing module in the vibration type liquid viscosity measurement system can be as follows: Figure 3

[0066] The phase-locked amplifier includes a signal channel, a reference channel, a phase-sensitive detector, and a low-pass filter; the signal channel is connected to the signal input end of the phase-sensitive detector; the reference channel is connected to the reference signal input end of the phase-sensitive detector; and the output end of the phase-sensitive detector is connected to the low-pass filter.

[0067] In some embodiments, the principle of measuring the viscosity of a target liquid by the vibration type liquid viscosity measurement system can be as follows:

[0068] The microcontroller controls the adjustable frequency signal generator to output two paths of sinusoidal wave drive signals with adjustable frequency and initial phase, i.e., an excitation signal and a reference signal. One path of the signals (the excitation signal) passes through the piezoelectric excitation element to act on the resonant cylinder, thereby providing an excitation force for the resonant cylinder. The other path of the signals (the reference signal) serves as the reference signal of the phase-locked amplifier. The adjustable frequency signal generator can be implemented by a dedicated direct digital frequency synthesizer (DDS) chip to output sinusoidal wave signals with adjustable frequency and initial phase.

[0069] After the excitation signal output by the adjustable frequency signal generator is converted between an electrical signal and a vibration signal on the excitation element, the vibration signal is transmitted to the resonant sensitive element placed in the target liquid, so that the resonant sensitive element stably vibrates in the target liquid. The pick-up element picks up the output signal of the resonant sensitive element, converts the output vibration displacement signal into an electrical signal, and inputs the electrical signal into the phase-locked amplifier.

[0070] The phase-locked amplifier converts the alternating voltage signal obtained by the pick-up element into a direct current voltage signal related to the selection of the reference signal. The reference signal is set as a sinusoidal wave signal with the same frequency as the excitation signal, and the initial phase is adjustable. The analog-to-digital converter can be implemented by a dedicated chip or by the analog-to-digital converter inside the microcontroller.

[0071] ​The obtained direct current voltage signal is converted into a digital signal by an analog-digital converter and is sent into a microcontroller. The phase difference between the sensor displacement response signal and the excitation signal is 90° as the judgment basis of the system resonance by using the phase frequency characteristic of the resonance system.

[0072] The microcontroller generates the frequency control word required by the adjustable frequency signal generator, adjusts the frequency of the adjustable frequency signal generator according to the voltage signal collected by the analog-digital converter, adjusts the output frequency of the signal generator according to the output size of the phase-locked amplifier, and when the collected voltage signal is equal to 0, the output frequency of the adjustable frequency signal generator at this time is the resonance frequency f of the system.

[0073] In some embodiments, the phase-locked amplifier comprises a signal channel, a reference channel, a phase-sensitive detector and a low-pass filter; the signal channel is connected with the phase-sensitive detector; the reference channel is connected with the phase-sensitive detector; and the phase-sensitive detector is connected with the low-pass filter. The working principle of the phase-locked amplifier can be as follows:

[0074] The phase-locked amplifier is based on the cross-correlation principle. Only when the input measured signal and the reference signal are of the same frequency can cross-correlation be realized, and the phase-locked amplifier has an output. The noise signal is generally different from the frequency of the measured signal, and after passing through the correlator, they are not correlated with each other, and there will be no output about the noise signal. Therefore, the phase-locked amplifier can be used to detect the periodic vibration signal from the complex noise signal. Therefore, the frequencies of the two sinusoidal wave driving signals output by the adjustable frequency signal generator should be the same, so as to realize cross-correlation.

[0075] Specifically, the basic structure block diagram of the phase-locked amplifier is as shown in Figure 4 The measured signal u i (t) is the vibration displacement signal of the resonance sensitive element picked up by the piezoelectric pickup, which contains a large amount of noise interference, and the useful signal part needs to be extracted from the noise signal; the signal channel amplifies the measured signal to obtain x(t) for facilitating the detection of the phase-sensitive detector; the reference signal u r(t) is the output signal of the adjustable frequency signal generator, in order to realize the correlation detection, the frequency of the reference signal should be equal to the frequency of the driving signal, the initial phase of the reference signal can be controlled by the frequency control word; the reference channel amplifies the amplitude of the reference signal, the control signal r(t) and the signal to be measured exist a fixed phase difference; the phase sensitive detector realizes the demodulation of the signal by multiplying the signal to be measured and the reference signal, the signal U(t) obtained contains AC component and DC component, after the signal passes through the low pass filter, the AC component is filtered out, the DC signal U0 obtained contains the amplitude information of the vibration signal and the phase difference information of the vibration signal and the reference signal. Therefore, after the processing of the lock-in amplifier, the periodic vibration displacement signal output by the resonant cylinder sensor is converted into a DC voltage signal related to the phase relationship of the reference signal, and the extraction of the resonant frequency signal of the sensor is realized.

[0076] From the working principle of the lock-in amplifier, it can be known that the output DC signal U0 is related to the selection of the reference signal, when measuring the resonant frequency f of the sensor, the reference signal and the excitation signal are sinusoidal signals with same frequency and same phase, and the phase difference of the two signals is 0°. According to the phase-frequency characteristic of the resonant system, that is, when the system resonates, the phase difference between the displacement response signal and the excitation signal is fixed at 90°, the specific mathematical analysis of the signals in the lock-in amplifier is as follows:

[0077] Assume that the signal to be measured output by the sensor is The reference signal r(t) = V r cos(ω0t), wherein: V s is the amplitude of the signal to be measured, V r is the amplitude of the reference signal, ω0 is the frequency of the two signals, is the phase difference of the two signals, the phase sensitive detector detects the signal to be measured by the phase of the reference signal, and the essence of the phase sensitive detector is a multiplier, so the output signal of the phase sensitive detector is After the high-frequency component is filtered out by the low-pass filter, the DC voltage signal is obtained It can be seen from the mathematical expression that the final output DC signal contains the amplitude signal and the phase information of the signal to be measured, when the signal to be measured is in phase with the reference signal, the output voltage signal reaches the maximum value, when the phase difference is 90°, the output voltage signal becomes zero.

[0078] In summary, the application has the following advantages: (1) the application obtains the reference resonant frequency, the first resonant frequency and the second resonant frequency of the target liquid, determines the frequency offset of the first resonant frequency and the second resonant frequency, and calculates the viscosity of the liquid according to the reference resonant frequency, the frequency offset, the viscosity-frequency calibration relationship and the resonant characteristic curve of the sensor model, so that the measurement process is simple and practical; (2) the viscosity calculation is realized by the microcontroller, and the measurement result can be displayed online; (3) compared with the sensor using quartz crystal as the resonant sensitive element, the resonant cylinder structure is not easy to be damaged, and is suitable for the measurement of liquid viscosity and density in the environment with large pressure fluctuation.

[0079] The various embodiments are described in a progressive manner in the specification, and each embodiment focuses on the difference from other embodiments, and the same or similar parts between the various embodiments can be referred to each other.

[0080] The principles and implementation manners of the application are described by using specific examples in the specification, and the above description of the examples is only used to help understand the method of the application and the core idea thereof; meanwhile, for the person skilled in the art, the specific implementation manner and application range of the application can be changed according to the idea of the application. In summary, the content of the specification should not be understood as the limitation of the application.

Claims

1. A method of measuring the viscosity of a liquid by means of vibration, characterised in that, The method comprises the following steps: Step 1, obtaining a reference resonant frequency, a first resonant frequency and a second resonant frequency of a target liquid; The reference resonant frequency is the frequency of a pick-up signal of a resonant sensitive element when the phase difference between the pick-up signal and a reference signal is 90° in the target liquid; the pick-up signal is a vibration signal generated by the resonant sensitive element under the excitation of an excitation signal with the same frequency and phase as the reference signal; The first resonant frequency is the frequency of a first pick-up signal of the resonant sensitive element when the phase difference between the first pick-up signal and the reference signal is 90° in the target liquid; the first pick-up signal is a vibration signal generated by the resonant sensitive element under the excitation of a first excitation signal; the frequency of the first excitation signal is the reference resonant frequency, and the phase of the first excitation signal leads the excitation signal with the same frequency and phase as the reference signal by a first set angle; The second resonant frequency is the frequency of a second pick-up signal of the resonant sensitive element when the phase difference between the second pick-up signal and the reference signal is 90° in the target liquid; the second pick-up signal is a vibration signal generated by the resonant sensitive element under the excitation of a second excitation signal; the frequency of the second excitation signal is the reference resonant frequency, and the phase of the second excitation signal lags the excitation signal with the same frequency and phase as the reference signal by a second set angle; the second set angle of the second excitation signal is equal in size to the first set angle of the first excitation signal; Step 2, determining the frequency offset of the first resonant frequency and the second resonant frequency; Step 3, obtaining a viscosity-frequency calibration relationship; Step 4, determining the viscosity of the target liquid according to the reference resonant frequency, the frequency offset and the viscosity-frequency calibration relationship; Step 4 specifically comprises: According to calculating the viscosity of the target liquid wherein, is the resonance frequency of the resonance sensitive element, is the shift of the resonance frequency, f 1 is the first resonance frequency, f 2 is the second resonance frequency, , , needs to be obtained by a viscosity-frequency calibration experiment.

2. A vibrating liquid viscosity measurement system characterized by, The vibration type liquid viscosity measurement method of claim 1 is applied to a vibration type liquid viscosity measurement system, which comprises a resonant sensitive element, an adjustable frequency signal excitation module, a resonant detection module and a signal processing module; The resonant sensitive element is used to be placed in a target liquid; The adjustable frequency signal excitation module is connected with the resonant sensitive element and is used to output an excitation signal with adjustable frequency to the resonant sensitive element; The resonant detection module is connected with the resonant sensitive element and the adjustable frequency signal excitation module, is used to collect a vibration signal of the resonant sensitive element and determine the phase difference between the vibration signal and a reference signal; the adjustable frequency signal excitation module is further used to adjust the frequency of the excitation signal until the phase difference is 90° when the phase difference is not 90°; The signal processing module is used to execute the vibration type liquid viscosity measurement method of claim 1.

3. The vibratory liquid viscosity measurement system of claim 2, wherein, The resonant sensitive element is a thin-walled cylindrical barrel.

4. The vibratory liquid viscosity measurement system of claim 2, wherein, The adjustable frequency signal excitation module comprises an adjustable frequency signal generator and an excitation element; The adjustable frequency signal generator is used to generate an excitation signal and a reference signal; The excitation element is connected with the resonant sensitive element and is used to provide excitation force to the resonant sensitive element under the action of the excitation signal.

5. The vibratory liquid viscosity measurement system of claim 2, wherein, The resonance detection module comprises a lock-in amplifier.

6. The vibratory liquid viscosity measurement system of claim 5, wherein, The lock-in amplifier comprises a signal channel, a reference channel, a phase-sensitive detector and a low-pass filter; the signal channel is connected with a signal input end of the phase-sensitive detector; the reference channel is connected with a reference signal input end of the phase-sensitive detector; an output end of the phase-sensitive detector is connected with the low-pass filter.

7. The vibratory liquid viscosity measurement system of claim 5, wherein, The resonance detection module comprises a vibration pickup element for collecting vibration signals of the resonance-sensitive element and transmitting the vibration signals to the lock-in amplifier.

8. The vibratory liquid viscosity measurement system of claim 2, wherein, The signal processing module comprises an analog-to-digital converter. The analog-to-digital converter is connected with the resonance detection module and is used for converting the vibration signals detected by the resonance detection module into digital signals.

9. The vibratory liquid viscosity measurement system of claim 8, wherein, The signal processing module comprises a microcontroller. The microcontroller is used for adjusting the frequency output by the adjustable frequency signal excitation module according to the digital signals output by the analog-to-digital converter, and executing the vibration type liquid viscosity measurement method of claim 1.

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