JP2003315233A - Measuring cell for quartz resonator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a measuring cell for quartz resonator usable also at a high- temperature and high-pressure specimen. <P>SOLUTION: The measuring cell 20 for quartz resonator is constituted by watertightly attaching a quartz resonator 31 to an opening 23a in a casing having an airtight space 23. A pressure regulator 40 composed of a double acting cylinder is installed additionally at the measuring cell 20, and a pressure of the airtight space and a pressure of the specimen are adjusted to be an equilibrium. Thereby, a high-pressure specimen or a specimen having a changing pressure is measured. Since there is no pressure difference between the surface and the back of the quartz resonator 31, the quartz resonator 31 can be made thin, and a measurement accuracy of the measuring cell 20 is enhanced. The inside of the airtight space 23 is set to a constant pressure. When there is the pressure difference between the surface and the back of the quartz resonator 31, its measured value is numerically corrected on the basis of a correlation between itself and a pressure change. When a detection circuit 30 connected to the quartz resonator 31 is installed outside the casing, the high-temperature specimen can be measured. When the detection circuit is installed inside the casing, the measurement accuracy can be increased. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a quartz oscillator measuring cell used for measuring a substance adsorption amount, density, viscosity or changes thereof in the field of physicochemical measurement, and a measuring device using the measuring cell. And the measuring method.

[0002]

2. Description of the Related Art Today, as a method of detecting the physicochemical characteristics of substances such as liquids and gases, the characteristics of the object to be measured are detected by measuring the resonance frequency based on the resonance phenomenon of a quartz oscillator. The quartz crystal microbalance method is generally used. As a conventional measuring cell for a crystal unit using this method, there is one as shown in FIG.

As shown in FIG. 1, the measuring cell 1 has a crystal resonator 2 attached to an opening 11 of a casing 10. The casing 10 has a cylindrical main body 12 whose lower surface is open and whose upper surface is closed, a bottom lid 14 which is screwed into a lower portion of the main body 12 through an O-ring 13 to close the lower surface opening, and an upper lid which is screwed into an upper portion of the main body. It consists of fifteen. The crystal resonator 2 is attached to the upper surface of the main body 12 via an O-ring 13, and the pressing plate 16 is further screwed onto the crystal resonator 2 via the O-ring 13, so that the crystal resonator 2 is attached to the main body 12. Fixed. The opening 11 is formed in the upper lid 15 so as to open the crystal resonator 2. A detection circuit (board) 3 is fixed in the casing 10, and a cable 4 led to the outside is attached to the detection circuit 3.
Is connected to the electrode 5 inside the casing 10.
, And the electrode 5 is connected to the crystal unit 2 by the spring-shaped terminal 6.

The measurement by the measuring cell 1 is performed, for example, when the object to be measured is a liquid and the measuring cell 1 is immersed in the liquid, the object to be measured enters through the opening 11 and the outer surface of the crystal resonator 2 ( Surface). Therefore, the resonance frequency or the like of the detection circuit including the crystal oscillator 12 changes according to the characteristic of the object to be measured, and the characteristic is detected as a signal by the detection circuit 3. The obtained detection signal is amplified and collected by the external impedance measuring device through the cable 4, and the physicochemical characteristics such as the density and viscosity of the object to be measured as well as dirt are analyzed.

[0005]

In the measuring cell 1, when the object to be measured is conductive, for example, when measuring the characteristics of the refined product in a chemical plant, the object to be measured enters the casing 10. Then, since there is a risk of short circuit or explosion proof in the detection circuit 3, the measuring cell 1 has a watertight structure in which the object to be measured does not enter the casing 10. For this reason, the pressure of the object to be measured is applied only to the opening 11 side of the crystal resonator 2, and if the pressure is high, the crystal resonator 2 may be damaged. When measuring an object under high pressure, such as a chemical plant, the fear becomes very high.

Further, the detection circuit 3 in the casing 10 is vulnerable to heat, and there is a problem that the operation becomes unstable at a high temperature of about 40 ° C. or more and cannot be used.

An object of the present invention is to make it applicable to an object to be measured under high pressure and high temperature.

[0008]

In order to solve the above-mentioned problems, the present invention decides to maintain the pressure difference between the front and back surfaces (outer and inner surfaces) of the crystal unit so as not to damage the crystal unit. It is a thing.

As a concrete means, an opening is formed in the casing, and a crystal oscillator is attached to the opening in a watertight manner,
A sealed space including the inner surface of the crystal unit is formed in the casing, and a pressure that the crystal unit can withstand is applied in advance to the sealed space. In this way, even if the measurement cell is immersed in the object to be measured and the pressure of the object to be measured is applied to the outer surface of the crystal unit, the pressure is applied to the inner surface of the unit in advance. Since the pressure difference is only small, the crystal oscillator will not be damaged even if the pressure of the object to be measured is increased to some extent.

As described above, when there is a pressure difference between the front surface and the back surface of the crystal unit, the measured values such as the resonance frequency of the crystal unit change, and it may not be possible to analyze the accurate characteristics of the object to be measured. is there. In this case, since there is a correlation between the change in pressure and the change in the measured value, the measured value may be numerically corrected based on the correlation. With this numerical correction, as long as the pressure difference between the front and back of the crystal unit is within the strength range of the crystal unit, it is possible to analyze the DUT without adjusting the pressure in the sealed space, simplifying the device. Can be realized and measurement becomes easy.

As another means, the pressure in the sealed space can be adjusted. By doing this, the pressure difference between the front and back of the crystal unit can be relaxed freely,
It can also be used for high-pressure objects to be measured. At this time, the pressures on the front and back surfaces may be constantly maintained in equilibrium.

In addition, in these configurations, if the detection circuit for the resonance frequency of the crystal unit is provided outside the casing and is separated from the object to be measured, there is an advantage that it is not affected by heat from the object to be measured. .

However, since the detection circuit detects a weak signal, it is preferable to provide the detection circuit at a position close to the crystal oscillator in order to prevent noise from flowing into the signal and to improve measurement accuracy. For this reason,
When a high-temperature measured object is not handled, the accuracy of measurement can be further improved by disposing the detection circuit in the casing.

On the other hand, as a means for adjusting the pressure of the sealed space, a pressure regulator may be attached. The pressure regulator is composed of, for example, a double-acting cylinder, the sealed space is connected to one liquid chamber of the cylinder to apply the pressure, and the other liquid chamber is applied with the pressure of the object to be measured. In addition, it is possible to employ a configuration in which an arbitrary pressure can be applied to the one liquid chamber. In this way, the pressure in the sealed space and the pressure of the object to be measured can always be adjusted to be in equilibrium. Accurate measurement is possible without damage.

At this time, the thinner the crystal unit, the higher the frequency and the higher the measurement accuracy. Therefore, if the pressure in the sealed space and the pressure of the object to be measured are always balanced, the crystal unit is not so much. The strength is no longer required, the crystal unit can be made thinner, and the measurement accuracy can be improved.

In order to apply a pressure to the sealed space, a gas is usually sealed in the sealed space, but an insulating liquid may be sealed instead of the gas. The use of this insulating liquid is preferable for safety. Moreover, when using gas, you may use inert gas, such as nitrogen, other than air.

Further, if there is no problem even if the object to be measured touches the inner surface of the crystal unit, if the pressure of the object to be measured is applied to the inner surface, the pressures on the front and back surfaces of the crystal unit are always kept the same. Therefore, the crystal unit can be made thinner.

In the present invention, the object to be measured is a liquid,
Since it is used regardless of the gas, watertight includes airtight.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is shown in FIG. 1, and a crystal oscillator measuring device of this embodiment is provided with a crystal oscillator measuring cell 20 immersed in an object to be measured, a pressure regulator 40 and a detector. And a circuit 30.

The crystal oscillator measuring cell 20 is composed of a casing 21 and a casing mounting flange 22. Inside the casing 21, there are three spaces: a sealed space 23, a circuit space 24, and a space 25 to be measured. Water-tight holes 23b, 24b, 2 which have openings 23a, 24a, 25a at one end and penetrate the casing mounting flange 22 at the other end.
5b.

In the opening 23a of the sealed space 23, a crystal oscillator 31 is fixed by a holding plate 27 with O-rings 26 having watertightness and chemical resistance on the front and back sides, and by this fixing, the crystal oscillator 31 is fixed. 31 is watertightly attached to the opening 23a, and a watertight space is formed inside thereof. Further, the circuit space 24 is provided side by side with the sealed space 23, and the opening 24 a is closed and fixed by the holding plate 27 via an O-ring 26. On the other hand, the measurement object space 25 has an opening 25a opened for pressure intake, and when the measurement cell is immersed in the measurement object, the measurement object enters the measurement object space 25 through the opening 25a. .

Electrodes are vapor-deposited on the crystal unit 31,
A signal cable 32 is connected to the electrode. The signal cable 32 passes through the circuit space 24 and the hole 2
4b is pulled out of the casing 21, and the detection circuit 30
Connected to. The detection circuit 30 is further connected to an external impedance measuring device.

The pressure regulator 40 has three spaces 41, 42, 43 therein, and a piston 44 is fitted into the space 42 in the middle thereof, and the liquid chamber 42a and the liquid chamber 42b are provided on both sides thereof.
And constitutes a double-acting cylinder. One of the liquid chambers 42a is connected to a sealed space pressurizing line 28 composed of a tube drawn out from the hole 23b of the sealed space 23, and the line 28 causes the pressure P of the sealed space 23 to rise.
(This pressure P can be seen by the pressure gauge 52.) is applied to the liquid chamber 42a. The other liquid chamber 42b is connected to a measured object pressurizing line 29 formed of a tube drawn out from the hole 25b of the measured object space 25, and the line 29 pressurizes the measured object pressure Q (this pressure Q Can be seen with the pressure gauge 51.) is applied to the liquid chamber 42b.

Therefore, the pressure of the object to be measured rises,
When the pressure of the object space 25 increases, the liquid chamber 42b
Since the pressure Q of the object to be measured is applied (Q> P) and the piston 44 is pushed upward, the valves 45a and 45b are pushed up against the elastic force of the spring 46 as shown by the broken line in FIG. By this pushing up, the valve 45a is opened, and the compressed air in the space 41 supplied from the compressed air cylinder 47 flows into the liquid chamber 42a. Since the liquid chamber 42a communicates with the sealed space 23 through the sealed space pressurizing line 28, the sealed space 23 is pressurized by the inflowing compressed air, and the sealed space pressure P becomes the measured object pressure Q. Equilibrate.

On the contrary, when the pressure of the object to be measured decreases and the pressure in the object space 25 decreases, the object pressure Q of the liquid chamber 42b decreases (Q <P) and the piston 44 moves downward. Since the valve 45b is pushed, the valve 45b is opened and the air in the liquid chamber 42a flows into the space 43 through the conduit 42c and is discharged to the outside. By discharging this air, the sealed space 23 communicating with the liquid chamber 42a via the sealed space pressurization line 28 is depressurized, and the measured object pressure P is balanced with the sealed space pressure Q. In this way, the measured object pressure P and the sealed space pressure Q are balanced, so that the same pressure is always applied to the front and back surfaces of the crystal oscillator 31. As the gas sealed in the sealed space 23 or the liquid chamber 42a, an inert gas such as nitrogen may be used instead of air.

This embodiment is configured as described above, and when the crystal oscillator measuring cell 20 is immersed in the object to be measured,
The outer surface of the crystal unit 31 touches the measured object, and the measured object flows into the measured object space 25.

When the crystal oscillator is vibrated and measured in this state, the pressure on the sealed space 23 side is adjusted by the pressure adjuster 40 according to the pressure of the object to be measured, and the front and back surfaces of the crystal oscillator 31 are adjusted. The pressure is balanced. As a result, it is possible to accurately measure an object under any pressure within the range of the function of the pressure regulator 40. For example, especially when used in a reaction can in a chemical plant, it is approximately 10 kgf / cm ² (9800
Although it is necessary to use it under a pressure of hPa) or higher, this crystal oscillator measuring device can be used even under the pressure of this reaction can by adjusting the pressure on the front and back surfaces of the crystal oscillator 31. Of course, since it has a pressure adjusting function, it is possible to measure not only the high pressure measured object but also the low pressure measured object, and the measured object whose pressure fluctuates.

By the way, when the pressure difference between the sealed space 23 and the object to be measured is not so large, the pressure that the crystal oscillator 31 can withstand in advance in the sealed space 23 without using the pressure regulator 40. It is also possible to employ a configuration in which is applied. For example, in this crystal oscillator measurement cell 20,
If a pressure B is applied to the sealed space 23 in advance, and the pressure difference between the front and back surfaces which the strength of the crystal unit 31 can withstand is A, the crystal unit measuring cell 20 has a pressure of B to be measured. It can be measured in the range of −A to B + A. Within this range, even if the pressure of the measured object in contact with the outer surface increases, measurement can be performed without adjusting the pressure as it is, and the structure of the crystal oscillator measurement cell 20 can be simplified.

When the function of the pressure regulator 40 is not used in this way, if a pressure difference occurs between the front and back surfaces of the crystal unit 31,
Since the measured values such as the resonance frequency change, the characteristic analysis of the measured object may be inaccurate as it is. Therefore, since the pressure difference and the change in the measured value have a correlation, the measured value of the detection circuit 30 is corrected based on the difference between the two pressures, and the characteristic of the measured object is analyzed. By this method, when the pressure difference is within the range of the strength of the crystal unit 31, the characteristics of the measured object can be analyzed by measuring the measured object without intentionally adjusting the pressure of the sealed space 23. , Measurement becomes easy.

Although the detection circuit 30 is provided outside the casing 21, it may be provided inside the circuit space 24 inside the casing 21. Since this detection circuit 30 detects a weak signal, it is preferable that the detection circuit 30 is provided near the crystal oscillator 21 so that noise will not flow in, and the measurement accuracy will be improved. Therefore, when the object to be measured having a high temperature is not handled, the accuracy of measurement can be further improved by providing the detection circuit 30 in the casing 21.

[0031]

As described above, the present invention can be used for a high temperature and high pressure object to be measured, and more accurate measurement can be performed.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a measuring device using a measuring cell for a quartz oscillator according to an embodiment.

FIG. 2 is a sectional view of a conventional example.

[Explanation of symbols]

20 measuring cell 21 casing 23 sealed space 24 circuit space 25 Object space 26 O-ring 28 Sealed space pressurization line 29 Pressurization line for object to be measured 30 Detection circuit (board) 31 crystal unit 32 signal cable 40 Pressure regulator 42a One liquid chamber 42b The other liquid chamber 42c conduit 44 piston 47 compressed air cylinder 51 Pressure gauge for measured object 52 Sealed space pressure gauge 53 cylinder pressure gauge

Claims (11)

[Claims] 1. A casing is formed with an opening, a crystal resonator is attached to the opening in a watertight manner, a sealed space including a surface inside the casing of the crystal resonator is formed in the casing, and the sealed space is preliminarily provided with the sealed space. A measuring cell for a crystal unit to which a pressure that the crystal unit can withstand is applied. 2. An opening is formed in a casing, and a crystal resonator is watertightly attached to the opening, a sealed space including a surface of the crystal resonator inside the casing is formed in the casing, and a pressure in the sealed space is controlled. Adjustable measuring cell for crystal unit. 3. The pressure application in the sealed space is performed by enclosing an insulating liquid.
Alternatively, the crystal oscillator measurement cell according to the item 2. 4. A detection circuit connected to a crystal oscillator is provided in the casing.
A measuring cell for a crystal unit according to. 5. A measuring device using the crystal oscillator measuring cell according to claim 2, wherein a pressure regulator is attached to the crystal oscillator measuring cell, and the pressure regulator is provided. Is capable of detecting the pressure of the object to be measured and applying a pressure to the sealed space of the crystal oscillator measurement cell, and based on the pressure of the object to be measured, the pressure is adjusted in the sealed space. A measuring device characterized in that 6. The pressure regulator is composed of a double-acting cylinder, the sealed space is connected to one of the liquid chambers of the cylinder to apply the pressure, and the pressure of the object to be measured is applied to the other liquid chamber. 6. The measuring device according to claim 5, wherein the pressure is applied to the one liquid chamber and an arbitrary pressure can be applied to the one liquid chamber. 7. A measuring method using the crystal oscillator measuring cell according to claim 2, wherein a pressure regulator is attached to the crystal oscillator measuring cell, and the pressure regulator is provided. Thus, the pressure of the object to be measured is detected, and the pressure in the sealed space of the crystal oscillator measurement cell is adjusted based on the detected value. 8. The measuring method according to claim 7, wherein the detection circuit is located outside the object to be measured. 9. When the difference between the pressure of the object to be measured and the pressure in the sealed space is within a certain range, the pressure in the sealed space is not adjusted,
The measurement method according to claim 7, wherein the measurement value is corrected based on the values of both the pressures. 10. The measuring method according to claim 7, wherein the pressure of the object to be measured and the pressure of the sealed space are substantially equalized. 11. A measuring method in which an opening is formed in a casing, a crystal oscillator is attached to the opening, and a pressure of an object to be measured is applied to the front and back surfaces of the crystal oscillator.