JPWO2007136069A1 - Coriolis flow meter - Google Patents

Abstract

A tubular body (53) provided with vibration generating means (31) on the outer surface of the central region, and provided with a pair of vibration detecting means (41, 42) at an equal distance from the vibration generating means in front and rear of the vibration generating means. ), A support base (54, 54) for fixing each of both ends of the tubular body, and a connecting member arranged in parallel to the tubular body for joining the two support bases to each other on both outer sides of the tubular body ( 55, 55), wherein each of the tubular body, each support base and each connecting member is made of the same piezoelectric single crystal material, and each of the vibration generating means and each vibration detecting means is a pair of A Coriolis flowmeter characterized by being composed of electrodes is easy to manufacture as a small-sized flowmeter and is not easily affected by the environmental temperature.

Description

  The present invention relates to a Coriolis flow meter that can be advantageously used for measuring a mass flow rate of a fluid moving at a minute flow rate.

  The Coriolis flow meter is a device that detects the Coriolis force acting on the fluid when vibration is applied to the fluid moving inside the tubular body, and measures the mass flow rate of the fluid correlated with the Coriolis force.

  FIG. 1 is a plan view showing a typical configuration of a conventional Coriolis flow meter. A Coriolis flow meter 10 of FIG. 1 includes a vibration generating means 11 on the outer surface of the central region, and a pair of front and rear (left and right directions in the figure) of the vibration generating means 11 with an equal distance from the vibration generating means 11. The tubular body 13 having the vibration detecting means 12, 12, the support bases 14 and 14 for fixing the both ends of the tubular body 13, and the tubular body that joins the two support bases to each other on both outer sides of the tubular body 13. The connecting members 15 and 15 are arranged in parallel to the body 13.

  Generally, the tubular body 13 is formed of a metal material such as titanium, zirconium, stainless steel, or hastelloy. Each support base 14 and each connection member 15 are formed of a metal material such as stainless steel. In general, an electromagnetic oscillator or a piezoelectric element is used as the vibration generating means 11, and an electromagnetic pickup or a piezoelectric element is used as each vibration detecting means 12.

  In the Coriolis flow meter 10, the mass flow rate of the fluid to be measured that moves inside the tubular body 13 is measured, for example, as follows. First, the vibration generating means 11 is driven to vibrate the tubular body 13 in a direction perpendicular to the length direction thereof, thereby causing Coriolis force to act on the fluid moving inside the tubular body 13. Next, an AC voltage corresponding to the vibration of the tubular body 13 that vibrates under the influence of the Coriolis force output from each of the pair of vibration detection units 12 and 12 is detected, and a phase difference between the AC voltages of the two is detected. Ask for. This phase difference is correlated to the Coriolis force, that is, the mass flow rate of the fluid. Then, the mass flow rate of the fluid is calculated based on the obtained phase difference value.

  Thus, a method for measuring the mass flow rate of the fluid moving inside the tubular body using the phase difference of the AC voltage output from each of the pair of vibration detection means is described in, for example, Patent Document 1. .

  FIG. 2 is a plan view showing a configuration of a conventional Coriolis flow meter described in Patent Document 2. As shown in FIG. The Coriolis flow meter 20 of FIG. 2 includes a pair of vibration generating means 21 and 21 on the outer surface of the central region, and a pair of vibrations at an equal distance from the vibration generating means in front and rear of the vibration generating means 21 and 21. A tubular body (flow tube) 13 provided with detection means 22, 22, support bases 14 and 14 for fixing both ends of the tubular body 13, and both support bases are joined to each other on both outer sides of the tubular body 13. It is comprised from the tubular connection member (counter tube) 25, 25 etc. which were arrange | positioned in parallel with the tubular body 13 to perform.

  As each vibration generating means 21 of the Coriolis flow meter 20, an electromagnetic oscillator including a magnet 21a and a pair of coils 21b and 21b is used. Each vibration generating means 21 is installed so as to connect the central regions of the tubular body 13 and the connecting member 25 to each other. Thereby, when each vibration generating means 21 is driven, both the tubular body 13 and each connecting member 25 can be vibrated in opposite phases. That is, each vibration generating means 21 is used as a means for generating vibration to be applied to the tubular body 13 and further as a means for generating vibration to be applied to each connecting member 25.

The Coriolis flow meter 20 has a configuration similar to that of a vibrating body in which a pair of tripod tuning fork vibrators are joined together at the tips of their arms (corresponding to the center position of the tubular body 13). is doing. As described above, when the tubular body 13 and the connecting members 25 (corresponding to the respective arm portions of the tripod tuning fork vibrator) are vibrated in opposite phases, the same as in the case of the tripod tuning fork vibrator. The leakage of the vibration of the tubular body 13 to each support base 14 is suppressed. Therefore, the Coriolis flow meter 20 can measure the mass flow rate of the fluid with high sensitivity by detecting a large Coriolis force acting on the fluid moving inside the tubular body 13.
JP-A-8-82541 JP 2001-289683 A

  The conventional Coriolis flowmeter shown in FIG. 1 or 2 is an electromagnetic oscillator or piezoelectric element used as vibration generating means on the outer surface of a tubular body formed of a metal material such as titanium, zirconium, stainless steel, or hastelloy. Since it is necessary to attach an electromagnetic pickup or a piezoelectric element used as each vibration detecting means, it is difficult to reduce the size. In addition, the conventional Coriolis flowmeter is a fluid that moves at a very small flow rate because the vibration frequency of the metal tubular body (frequency of vibration applied to the fluid to be measured) fluctuates due to the influence of the environmental temperature. It is difficult to measure the mass flow rate with high accuracy.

  An object of the present invention is to provide a Coriolis flow meter that is easy to manufacture as a small flow meter and is not easily affected by environmental temperature.

  The present invention provides a tubular body having vibration generating means on the outer surface of the central region, and a pair of vibration detecting means at an equal distance from the vibration generating means in front and rear of the vibration generating means, and both ends of the tubular body A Coriolis flowmeter comprising: a support base for fixing each of the sections; and a connecting member arranged in parallel to the tubular body for joining the support bases to each other on both sides of the tubular body. The Coriolis flowmeter is characterized in that each of the base and each connecting member is made of the same piezoelectric single crystal material, and each of the vibration generating means and each vibration detecting means is composed of a pair of electrodes.

Preferred embodiments of the Coriolis flowmeter of the present invention are as follows.
(1) On the outer surface opposite to the side where the vibration generating means is attached in the central region of the tubular body, there is provided vibration generating means different from the above constituted by a pair of electrodes.
(2) Each connecting member has a mass in the range of 0.3 to 3.0 times the mass of the tubular body, and is formed on the outer surface of the central region from a pair of electrodes. Vibration generating means is provided.
(3) The tubular body is configured by laminating plate materials formed of the same piezoelectric single crystal material.
(4) Each support base and each connection member are configured by laminating plate materials made of the same piezoelectric single crystal material.
(5) The piezoelectric single crystal material is quartz.

  In the Coriolis flowmeter of the present invention, each of the tubular body, each support base and each connection member is formed of the same piezoelectric single crystal material (particularly quartz), and a pair of electrodes are provided on the outer surface of the tubular body. Therefore, it is easy to manufacture as a small flow meter and is not easily affected by the environmental temperature.

  The Coriolis flowmeter of the present invention will be described with reference to the accompanying drawings. FIG. 3 is a perspective view showing a configuration example of the Coriolis flow meter of the present invention, and FIG. 4 is a cross-sectional view of the Coriolis flow meter 30 cut along the cutting line I-I written in FIG. . However, FIG. 4 does not include the vibration generating means 31 and the pair of vibration detecting means 41 and 42 shown in FIG.

  The Coriolis flow meter 30 shown in FIGS. 3 and 4 includes a vibration generating means 31 on the outer surface of the central region, and a pair of vibration detections at an equal distance from the vibration generating means 31 in front and rear of the vibration generating means 31. The tubular body 53 provided with the means 41 and 42, the support bases 54 and 54 for fixing the both ends of the tubular body 53, and the tubular body 53 for joining both the support bases to each other on both sides of the tubular body 53 are provided. It is comprised from the connection members 55 and 55 etc. which were arrange | positioned. In the Coriolis flow meter 30 of the present invention, each of the tubular body 53, each support base 54, and each connection member 55 is formed of the same piezoelectric single crystal material, and the vibration generating means 31, the vibration detecting means 41, and the vibration The main feature is that each of the detection means 42 includes a pair of electrodes.

Examples of the piezoelectric single crystal material forming the tubular body, each support base and each connection member of the Coriolis flowmeter of the present invention include quartz, lithium niobate (LiNbO ₃ ), and lithium tantalate (LiTaO ₃ ). It is done.

  A piezoelectric element composed of a piezoelectric body made of a piezoelectric single crystal material and a pair of electrodes attached to the surface of the piezoelectric element has an effect of environmental temperature compared to the case of using a typical piezoelectric ceramic material as a piezoelectric material. Not easily received (vibrates at a stable frequency even when the ambient temperature fluctuates).

  In the Coriolis flow meter 30 shown in FIG. 3 and FIG. 4, quartz that can constitute a vibrator that is not easily affected by environmental temperature is used as the piezoelectric single crystal material. The arrows 56, 57, and 58 shown in FIG. 3 indicate the directions of the X-axis (electrical axis), Y-axis (mechanical axis), and Z-axis (optical axis) of the crystal axis of the crystal, respectively. In the following description, the Coriolis flowmeter of the present invention will be described with a case where quartz is used as the piezoelectric single crystal material as a representative example.

  The vibration generating means 31 is composed of a pair of electrodes 31a and 31a. Similarly, the vibration detection means 41 is composed of a pair of electrodes 41a, 41a, and the vibration detection means 42 is composed of a pair of electrodes 42a, 42a. Each of these electrodes is formed from a metal material such as gold, indium, or aluminum.

  The pair of electrodes 31 a and 31 a of the vibration generating means 31 are arranged in parallel with a gap therebetween along the X-axis direction of the crystal forming the tubular body 53. The arrangement of the pair of electrodes 41 a and 41 a of the vibration detection unit 41 and the pair of electrodes 42 a and 42 a of the vibration detection unit 42 are the same as those of the vibration generation unit 31.

  When an AC voltage is applied to the pair of electrodes 31a and 31a of the vibration generating means 31, only the upper wall of the quartz tubular body 53 expands and contracts (vibrates) in the Y-axis direction. On the other hand, the tubular body 53 is supported by a rigid frame composed of support bases 54 and 54 for fixing each of both end portions thereof, and connection members 55 and 55 for joining the both support bases to each other. It is fixed. As a result, the tubular body 53 vibrates in the vertical direction (a direction parallel to the Z-axis of the crystal) with both ends thereof as vibration nodes. By applying this vibration to the fluid moving inside the tubular body 53, Coriolis force acts on the fluid.

  That is, in the Coriolis flow meter 30, a piezoelectric element constituted by a wall of a tubular body 53 made of quartz (piezoelectric single crystal material) and a pair of electrodes 31a and 31a of the vibration generating means 31 provided on the surface thereof. Is used to apply vibration to the fluid moving inside the tubular body 53.

  The AC voltage output from the pair of electrodes 41a and 41a of the vibration detecting means 41 provided in the tubular body 53 that vibrates while being affected by the Coriolis force and the pair of electrodes 42a and 42a of the vibration detecting means 42 are provided. The phase difference from the AC voltage output from the.

  That is, in the Coriolis flow meter 30, a piezoelectric element constituted by a wall of a tubular body 53 made of quartz (piezoelectric single crystal material) and a pair of electrodes 41a and 41a of the vibration detecting means 41 provided on the surface thereof. And the phase difference of the said alternating voltage is calculated | required using the piezoelectric element comprised by the wall body of the tubular body 53, and a pair of electrode 42a, 42a of the vibration detection means 42 with which the surface was equipped.

  As described above, since the obtained phase difference is correlated with the Coriolis force, that is, the mass flow rate of the fluid, the mass flow rate of the fluid moving in the tubular body 53 is calculated based on the value of the phase difference. be able to.

  As described above, the Coriolis flow meter 30 of the present invention includes an electromagnetic oscillator or piezoelectric element that applies vibration to a fluid to be measured, and an electromagnetic pickup that detects vibration of a tubular body, as in the case of a conventional Coriolis flow meter. Since it is not necessary to attach the piezoelectric element to the outer surface of the tubular body, it is easy to manufacture as a small flow meter.

  In the conventional Coriolis flowmeter, for example, a part of the vibration wave generated by the electromagnetic oscillator or the piezoelectric element is reflected on the outer surface of the tubular body, and the energy of the vibration wave is converted into heat and lost. Produce. On the other hand, in the Coriolis flowmeter of the present invention, the vibration energy as described above is used to directly vibrate the wall of the tubular body, not to vibrate the tubular body by applying the vibration generated by the electromagnetic oscillator or the piezoelectric element. There will be no loss. Therefore, the Coriolis flowmeter of the present invention is capable of measuring a mass flow rate of a fluid with high sensitivity because vibration having a large amplitude is applied to the fluid to be measured and a large Coriolis force can be applied to the fluid. Can do.

  In the Coriolis flow meter 30, the tubular body 53 is formed of quartz (piezoelectric single crystal material) as described above, and can impart stable vibration to the fluid even when the environmental temperature fluctuates. Therefore, the mass flow rate of the fluid moving inside the tubular body 53 can be measured with a stable high sensitivity.

  Furthermore, in the Coriolis flow meter 30 of the present invention, not only the tubular body 53 but also each support base 54 and each connection member 55 are the same piezoelectric single crystal material as the piezoelectric single crystal material forming the tubular body 53. (Ie, quartz).

  Thereby, in the Coriolis flow meter 30, for example, even when the tubular body 53, the support bases 54, and the connection members 55 are thermally expanded due to an increase in environmental temperature, the respective thermal expansion coefficients are the same. Therefore, the internal stress generated in the tubular body 53 is extremely small. For this reason, the Coriolis flow meter 30 can measure the mass flow rate of the fluid with extremely stable and high accuracy even when the environmental temperature fluctuates. When a large internal stress is generated in the tubular body 53 due to a change in the environmental temperature, the AC voltage output from each of the pair of vibration detection means 41 and 42 is changed, so that the measurement accuracy of the mass flow rate of the fluid is lowered.

  FIG. 5 is an exploded perspective view of the Coriolis flow meter 30 of FIG. 3, and FIG. 6 is a perspective view showing a state in which the piezoelectric single crystal plate 59c shown in FIG. The Coriolis flow meter 30 can be manufactured by the following procedure, for example.

  First, three quartz plates 59a, 59b, 59c (three plates formed of the same piezoelectric single crystal material) are prepared. Next, two long holes 61 and 61 are formed in each of the quartz plates 59a and 59c, and two long holes 61 and 61 similar to the above are formed in the quartz plate 59b, and a flow path of the fluid to be measured (see FIG. 4: 53a) is formed. A representative example of a method for forming a long hole in each quartz plate is an etching method. The etching processing method is a known processing method that is widely used when manufacturing a tuning fork vibrator for a watch.

  Next, on the surface of the quartz plate 59a, a pair of electrodes 31a, 31a constituting the vibration generating means 31, a pair of electrodes 41a, 41a constituting the vibration detecting means 41, and a pair of electrodes 42a constituting the vibration detecting means 42 are provided. , 42a.

  In order to apply an AC voltage to the pair of electrodes 31a and 31a of the vibration generating means 31, an AC power source may be directly connected to these electrodes, but the tubular body (FIG. 4: 53) is stably vibrated. For this reason, the AC power source 63 is normally connected to the electrodes 31a and 31a via, for example, electric wirings 31b and 31b extending to one of the support bases (FIG. 3: 54). In addition, the example of the material which forms each of the electrical wiring 31b and 31b is the same as that of the case of the electrodes 31a and 31a.

  Each of the electrodes 31a and 31a and the electric wirings 31b and 31b can be formed by using a known thin film forming method such as a vacuum evaporation method or a sputtering method. Each electrode 31a and each electric wiring 31b are set in a predetermined shape by, for example, photolithography or a mask method.

  Further, as shown in FIG. 6, the surface of the quartz plate 59c (the lower surface of the quartz plate 59c shown in FIG. 5) is provided with vibration generating means 32 different from the above, which is composed of a pair of electrodes 32a and 32a. It is preferable. As shown in FIGS. 3, 5, and 6, the vibration generating means 32 is disposed on the outer surface of the central region of the tubular body 53 opposite to the side on which the vibration generating means 31 is attached. As in the case of the vibration generating means 31, an AC power source 64 is connected to each of the pair of electrodes 32a, 32a of the vibration generating means 32 via electric wirings 32b, 32b.

  An alternating voltage having a phase opposite to the phase of the alternating voltage applied to the pair of electrodes 31 a and 31 a of the vibration generating means 31 is applied to the pair of electrodes 32 a and 32 a of the vibration generating means 32. As a result, the upper wall body and the lower wall body of the tubular body (FIG. 4: 53) expand and contract in the Y-axis direction in opposite phases. As a result, the tubular body vibrates up and down with a large amplitude. For this reason, a large Coriolis force acts on the fluid moving inside the tubular body, and the measurement sensitivity of the mass flow rate of the fluid is increased.

  Then, the quartz plate 59a, the quartz plate 59b, and the quartz plate 59c (preferably provided with the vibration generating unit 32) provided with the vibration generating unit 31, the pair of vibration detecting units 41 and 42, are overlapped and joined. To do.

  As a method of joining the quartz plate 59a, the quartz plate 59b, and the quartz plate 59c, a known quartz (or glass) bonding method can be used. Examples of the method of joining the quartz plates include a method of joining the quartz plates via an adhesive material such as adhesive glass, water glass, or an organic adhesive, and a method of thermally bonding the quartz plates in close contact with each other. Raru.

  Finally, each of both ends of the quartz plate 59b (the portion indicated by the two-dot chain line in FIG. 5) is cut using a cutting device (eg, dicer), thereby producing the Coriolis flow meter 30 of FIG. be able to.

  A pair of plate materials 59d and 59d used when the Coriolis flow meter 30 is installed in a case (FIG. 8: 80) described later may be provided on the bottom surface of the crystal plate 59c. Each plate member 59d may be formed of quartz or a rubber material typified by silicone rubber so that the vibration of the tubular body does not leak to the case via each support base (FIG. 3: 54). May be.

  As shown in FIGS. 3 to 5, the tubular body 53 of the Coriolis flowmeter 30 of the present invention has three plates (quartz plates 59 a, 59 b, 59 c in FIG. 5) formed from the same piezoelectric single crystal material. It is preferable that these are laminated. This is because the internal stress generated in the tubular body 53 due to fluctuations in the environmental temperature is reduced, and the flow path 53a of the tubular body 53 that moves the fluid to be measured can be easily configured.

  Further, each support base 54 and each connection member 55 are configured by laminating three plate materials (crystal plates 59a, 59b, 59c in FIG. 5) formed of the same piezoelectric single crystal material. It is preferable. As a result, the internal stress generated in the tubular body 53 due to the fluctuation of the environmental temperature is reduced as described above, and the Coriolis flow meter 30 can be manufactured by a simple method of laminating the three plates as described above. is there.

The Coriolis flowmeter of the present invention can be constructed by separately manufacturing a tubular body, each support base, and each connecting member and joining them together. However, when the width of the tubular body is extremely thin (for example, FIG. In the case where the width W ₁ of the tubular body 53 described in 4 is about several millimeters), it is necessary to carefully perform the joining operation so that the tubular body (or each support base and each connection member) is not damaged. There is.

  As described above, when the Coriolis flow meter 30 is manufactured by laminating three plates (quartz plates 59a, 59b, 59c in FIG. 5), for example, even if the width of the tubular body 53 is extremely thin, There is no need to handle the tubular body 53 alone. For this reason, the Coriolis flow meter 30 can be configured extremely small by a simple operation.

The Coriolis flow meter 30 shown in FIG. 3 has, for example, a quartz plate (FIG. 5: 59a) used for its production having a width of 10 mm, a length of about 20 mm, and a tubular body width (FIG. 4: W ₁ ). It is set to 1.2 mm and can be manufactured in an extremely small size.

In the Coriolis flow meter 30 of the present invention, the length of each support 54 (for example, the length L ₁ shown in FIG. 3) is 2 to 20 times (particularly 2) the width of the tubular body 53 (FIG. 4: W ₁ ). 10 to 10 times). The width of each connecting member 55 (for example, the width W ₂ shown in FIG. 4) is in the range of 2 to 20 times (particularly 2 to 10 times) the width of the tubular body 53 (FIG. 4: W ₁ ). Is preferred.

  Thereby, the mass of each support base 54 or each connection member 55 becomes sufficiently large with respect to the mass of the tubular body 53, and the vibration of the tubular body 53 is difficult to leak to the outside through each support base 54. That is, even when the tubular body 53 is vibrated when measuring the mass flow rate of the fluid, each support base 54 or each connection member 55 is less likely to vibrate. A large Coriolis force can be applied to the fluid moving inside the fluid. In addition, the AC voltage generated at the pair of electrodes of each vibration detection means hardly includes voltage noise based on vibration generated at each support base 54 or each connection member 55. For this reason, the measurement sensitivity and measurement accuracy of the Coriolis flow meter 30 are increased.

  As described above, in the Coriolis flow meter 30 of the present invention, the alternating voltage generated at the pair of electrodes 41a and 41a of the vibration detecting means 41 and the alternating current generated at each of the pair of electrodes 42a and 42a of the vibration detecting means 42. Based on the phase difference from the voltage, the mass flow rate of the fluid to be measured is calculated.

  The mass flow rate of the fluid to be measured is determined by, for example, connecting the pair of electrodes 41a and 41a of the vibration detection unit 41 and the pair of electrodes 42a and 42a of the vibration detection unit 42 to an oscilloscope or a synchroscope. Can be calculated based on the phase difference obtained by observing the waveform.

  However, normally, as shown in FIG. 5, the phase difference between the AC voltage generated at the pair of electrodes 41a and 41a of the vibration detecting means 41 and the AC voltage generated at the pair of electrodes 42a and 42a of the vibration detecting means 42 is calculated. An arithmetic device 65 that calculates and calculates the mass flow rate of the fluid based on the obtained phase difference is used.

  The pair of electrodes 41a and 41a of the vibration detection unit 41 and the pair of electrodes 42a and 42a of the vibration detection unit 42 are connected to the arithmetic unit 65 via, for example, the electric wirings 41b and 41b and the electric wirings 42b and 42b, respectively. Connected.

FIG. 7 is a block diagram of the arithmetic device 65 shown in FIG. The arithmetic unit 65 includes an amplifier 71 that amplifies the AC voltage V ₄₁ output from the pair of electrodes of the vibration detection means 41, an amplifier 72 that amplifies the AC voltage V ₄₂ output from the pair of electrodes of the vibration detection means 42, and each amplifier. A phase difference detection circuit 73 that obtains the phase difference between the two AC voltages from the electrical signal output from the sensor, and a mass flow rate calculation circuit 74 that calculates the mass flow rate from the output signal of the detection circuit 73 and outputs an electrical signal 75 indicating the mass flow rate. It is composed of The electrical signal 76 indicating the phase difference output from the phase difference detection circuit 73 is, for example, the frequency of the AC voltage generated by the AC power source (FIG. 5: 63) connected to the vibration generating means (FIG. 5: 31). Used for control. Such an arithmetic unit 65 is known and disclosed in, for example, Patent Document 1 described above. The arithmetic device connected to the Coriolis flow meter of the present invention is not limited to the arithmetic device shown in FIG. 7, and a known arithmetic device for a Coriolis flow meter can be used.

  FIG. 8 is a diagram showing an example of the usage of the Coriolis flow meter 30 of FIG. 3, and FIG. 9 is a view of the Coriolis flow meter 30 and the case cut along the cutting line II-II entered in FIG. FIG.

  As shown in FIGS. 8 and 9, the Coriolis flow meter 30 is preferably housed and used in a case 80, for example. The case 80 includes a main body 81, side plates 82 and 82, and a lid 83. Each side plate 82 is formed with a rectangular hole 82a connected to the flow path 53a of the tubular body 53 of the Coriolis flow meter 30 and a circular hole 82b connected to the hole 82a. A connection pipe 84 having a circular cross section is provided on the outer surface of each side plate 82 to facilitate connection between the Coriolis flow meter 30 and a pipe (not shown) through which a fluid to be measured flows. .

  The material of the case 80 is not particularly limited. For example, when a metal material typified by stainless steel is used, it is possible to suppress a decrease in measurement accuracy of the mass flow rate of the Coriolis flow meter 30 due to the influence of electromagnetic waves existing in the external environment. Can do.

In addition, the length L ₂ of each plate member 59 d provided in the Coriolis flow meter 30 is preferably 5 to 50% (particularly in the range of 10 to 50%) of the length L ₁ of each support base 54. Thereby, since the difference in mass between each support base 54 and each plate material 59d becomes large, the vibration of the tubular body 53 of the Coriolis flow meter 30 hardly leaks to the case 80 via each support base 54 and each plate material 59d. Become.

  FIG. 10 is a perspective view showing another configuration example of the Coriolis flow meter of the present invention, and FIG. 11 is a sectional view of the Coriolis flow meter 100 cut along the cutting line III-III written in FIG. FIG. 12 is an exploded perspective view of the Coriolis flow meter 100 of FIG. FIG. 13 is a perspective view showing a state in which the piezoelectric single crystal plate 109c shown in FIG.

  In the configuration of the Coriolis flow meter 100 in FIG. 10, each connecting member 105, 105 has a mass equal to the mass of the tubular body 53 (set to a tubular shape having the same size as the tubular body 53), and its central region. The vibration generating means 33 different from the above is provided on the outer surface of the support member 104, and the support base 104 is connected to the hollow portion 105a of the connection member 105. 3 is the same as the Coriolis flow meter 30 in FIG. 3 except that the holes 104a and 104a are formed.

  Thus, by making the mass of each connecting member 105 equal to the mass of the tubular body 53, the Coriolis flow meter 100 is a pair of tripod tuning fork vibrators as in the case of the Coriolis flow meter of Patent Document 2 described above. Are set to have the same configuration as that of the vibrating body joined and integrated with each other at the tip of each arm portion (corresponding to the center position of the tubular body 53).

  For this reason, when an AC voltage generated by the AC power source 63 is applied to the electrical wirings 106, 106 connected to the vibration generating means 31, 33, 33, the tubular body 53 and each connecting member 105 (of a tripod tuning fork vibrator). (Corresponding to the respective arm portions) vibrate up and down at opposite phases, thereby preventing the vibration of the tubular body 53 from leaking to the respective support bases 104. For this reason, the Coriolis flow meter 100 in FIG. 10 can measure the mass flow rate of the fluid with high sensitivity by detecting a large Coriolis force acting on the fluid moving inside the tubular body 53. it can.

  As in the case of the Coriolis flow meter 30 of FIG. 3, on the outer surface opposite to the side where the vibration generating means 31 is attached in the central region of the tubular body 53 of the Coriolis flow meter 100 shown in FIGS. A pair of electrodes 34a, 32a, a pair of electrodes 34a, 32a, 32a on the outer surface of the connecting member 105 opposite to the side on which the vibration generating means 33 is attached. If the vibration generating means 34 different from the above configured from 34 a is provided, the tubular body 53 and further each connecting member 105 can be vibrated up and down with a large amplitude, so that the mass of the Coriolis flow meter 100 is increased. Increased flow measurement sensitivity.

  In the Coriolis flowmeter of the present invention, each connection member is 0.3 to 3.0 times the mass of the tubular body (particularly 0.5 to 2. It is preferable to have a mass in the range of (0 times).

  When the fluid to be measured is known, each connecting member is 0.3 to 3.0 times (particularly 0.5 to 2.0 times) the mass of the tubular body filled with the fluid to be measured. It is preferable to have a mass within the range.

  In the Coriolis flow meter 100, if the fluid to be measured is known, the same fluid as the fluid to be measured is put into the cavity 105a of each connection member 105 from the opening of the through hole 104a of the support base 104, and the opening is opened. By covering the part, the mass of each connection member 105 can be made equal to the mass of the tubular body 53 filled with the fluid to be measured. When the measurement target fluid is a gas, the mass of each connection member 105 is not limited to the measurement target fluid (gas) even if the same gas as the measurement target gas is not put into the cavity 105a of each connection member 105. ) Is substantially equal to the mass of the tubular body 53 filled with.

  An AC power supply 63 is used for the pair of electrodes 33a, 33a of each vibration generating means 33, and an alternating current having a phase opposite to the phase of the AC voltage applied to the pair of electrodes 31a, 31a of the vibration generating means 31 is used. A voltage is applied. An AC voltage having a phase opposite to the phase of the AC voltage applied to the pair of electrodes 31a, 31a of the vibration generating means 31 is applied to the pair of electrodes 32a, 32a of the vibration generating means 32 using an AC power source 64. Is granted. The pair of electrodes 34a, 34a of each vibration generating means 34 has a phase opposite to the phase of the AC voltage applied to the pair of electrodes 33a, 33a of each vibration generating means 33 using an AC power source 64. AC voltage is applied.

  Further, the manufacturing method of the Coriolis flow meter 100 is the same as that of the Coriolis flow meter 30 of FIG. 3 except that the shapes of the crystal plates 109a, 109b, and 109c and the number of vibration generating means and vibration detecting means are different. Therefore, detailed description is omitted.

  The Coriolis flow meter of the present invention is easy to manufacture as a small flow meter and is not easily affected by the environmental temperature (even if the external temperature varies, the mass flow rate of the fluid can be measured with high stability and stability). The Coriolis flowmeter of the present invention is a gas (for example, oxygen gas, nitrogen gas, argon gas, etc.) or a liquid (for example, pure water) that needs to be controlled to a minute flow rate, for example, in a semiconductor manufacturing facility or a medical gas supply facility. Water, liquefied gas, etc.) can be advantageously used for measuring the mass flow rate.

It is a top view which shows the structure of the conventional Coriolis flowmeter. It is a top view which shows another structural example of the conventional Coriolis flowmeter. It is a perspective view which shows the structural example of the Coriolis flowmeter of this invention. It is sectional drawing of the Coriolis flowmeter 30 cut | disconnected along the cutting line II entered in FIG. However, FIG. 4 does not include the vibration generating means 31 and the pair of vibration detecting means 41 and 42 shown in FIG. FIG. 4 is an exploded perspective view of the Coriolis flow meter 30 of FIG. 3. FIG. 6 is a perspective view showing a state in which the piezoelectric single crystal plate 59c shown in FIG. It is a block diagram of the arithmetic unit 65 shown in FIG. It is a figure which shows an example of the aspect of use of the Coriolis flowmeter 30 of FIG. It is sectional drawing of the Coriolis flow meter 30 and the case 80 cut | disconnected along the cutting line II-II line entered in FIG. It is a perspective view which shows another structural example of the Coriolis flowmeter of this invention. It is sectional drawing of the Coriolis flowmeter 100 cut | disconnected along the cutting line III-III line entered in FIG. FIG. 11 is an exploded perspective view of the Coriolis flow meter 100 of FIG. 10. FIG. 13 is a perspective view showing a state where the piezoelectric single crystal plate 109c shown in FIG.

Explanation of symbols

10, 20 Coriolis flow meter 11 Vibration generating means 12 Vibration detecting means 13 Tubular body 14 Support base 15 Connection member 21 Vibration generating means 21a Magnet 21b Coil 22 Vibration detecting means 25 Connection member 30 Coriolis flow meters 31, 32, 33, 34 Vibration Generation means 31a, 32a, 33a, 34a Electrodes 31b, 32b Electrical wiring 41, 42 Vibration detection means 41a, 42a Electrodes 41b, 42b Electrical wiring 50 Coriolis flow meter 53 Tubular body 53a Channel 54 Support base 55 Connection members 56, 57, 58 Arrows 59a, 59b, 59c indicating crystal axes of crystal Crystal plate 59d Plate members 61, 62 Long holes 63, 64 Power supply 65 Arithmetic devices 71, 72 Amplifier 73 Phase difference detection circuit 74 Mass flow rate calculation circuit 75 Electric signal indicating mass flow rate 76 Electrical signal indicating phase difference 80 Case 81 Body 82 Side plate 83 82a, 82b hole 84 connecting pipe 100 Coriolis flowmeter 104 supporting base 104a through hole 105 connecting member 105a cavity 106 electric wiring 109a, 109b, 109c crystal plate

Claims (6)

  A tubular body provided with vibration generating means on the outer surface of the central region, and a pair of vibration detecting means at an equal distance from the vibration generating means in front and rear of the vibration generating means, and fixing both ends of the tubular body A Coriolis flowmeter including a support base that is connected to each other on both sides of the tubular body and a connection member that is arranged in parallel to the tubular body, the tubular body, each support base, and each connection member Are formed of the same piezoelectric single crystal material, and each of the vibration generating means and each vibration detecting means is composed of a pair of electrodes.   The vibration generating means different from the said comprised from a pair of electrodes is provided in the outer surface on the opposite side to the side to which the said vibration generating means was attached of the center area | region of a tubular body. Coriolis flow meter.   Each connecting member has a mass in the range of 0.3 to 3.0 times the mass of the tubular body, and has a vibration generating means different from the above, which is composed of a pair of electrodes on the outer surface of the central region. A Coriolis flow meter according to claim 1.   The Coriolis flowmeter according to claim 1, wherein the tubular body is configured by laminating plate materials formed of the same piezoelectric single crystal material.   5. The Coriolis flow meter according to claim 4, wherein each of the support bases and each of the connection members is configured by laminating plate materials formed of the same piezoelectric single crystal material.   The Coriolis flow meter according to claim 1, wherein the piezoelectric single crystal material is quartz.

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