JP2001133304A - Ultrasonic sensor and ultrasonic flowmeter using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oscillator capable of easily providing an ultrasonic sensor having a prescribed high impedance and a structure for the retaining member thereof. SOLUTION: An oscillator 12 is adhered to the surface 11 of a cylindrical sensor-retaining member 10, which is opposed to the side surface 7 for carrying a fluid to be measured of a flowmeter body 1, to constitute an ultrasonic sensor. A spring 15 regularly presses the sensor retaining member 10 and the oscillator 12 to the side surface 7 of a sensor insertion part 6. A recessed part 111 having prescribed diameter and depth is provided in the center of the surface 11 for adhering the oscillator 12 of the sensor-retaining member 10 while leaving the peripheral part of the oscillator 12, and the oscillator 12 is adhered to the sensor-retaining member 10 through an adhesive 112 filled in the recessed part 111. Since the oscillator 12 is not directly closely fitted to the sensor-retaining member 10 but adhered through the adhesive 112 having a prescribed thickness, the ultrasonic sensor can have a high impedance and generate a high receiving output.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an ultrasonic sensor in an ultrasonic flow meter, an ultrasonic eddy flow meter, and the like.
More specifically, the present invention relates to a structure of an ultrasonic sensor used for a flow meter or the like from which a homogeneous ultrasonic sensor having a large impedance value can be easily obtained.

[0002]

2. Description of the Related Art Ultrasonic flow meters and ultrasonic vortex flow meters are well known as flow meters having an ultrasonic sensor. For example,
The ultrasonic vortex flowmeter detects alternating flow velocity changes due to Karman vortex generation as ultrasonic frequency changes, and installs an ultrasonic transceiver opposite the vortex generator,
The fixed frequency transmitted from the transmitter passes through the measurement fluid and is received by the receiver. The transmitted ultrasonic waves change periodically in sound speed due to the meandering flow caused by the vortex generation, and the arrival time at the receiver changes. Therefore, the receiver receives an ultrasonic wave which has been subjected to frequency modulation proportional to the cycle of the vortex, and detects the vortex by measuring the modulation frequency to measure the flow rate.

The ultrasonic transmitter / receiver used in such a flow meter usually has a structure in which a vibrator is housed in a holder. There are known sensors equipped with a sensor (Japanese Patent Laid-Open Nos. 3-269322 and 6-1601).
No. 36). These are designed exclusively for the purpose of improving the adhesion between the vibrator and the flow channel wall, so that the holder and the plug are fixed by ultrasonic welding, or after the sensor is placed in the insertion hole, Since the holding member is fixed to the surface of the main body, even if a failure or the like occurs in the sensor, its replacement or reattachment cannot be easily performed. Therefore, an ultrasonic sensor mounting structure that can be easily mounted and replaced and that can be stably arranged at a predetermined position has been proposed (Japanese Patent No. 2880150).
issue).

[0004]

In order to explain the construction of the mounting portion of the ultrasonic sensor of the conventional ultrasonic flow meter,
As an example, an ultrasonic vortex flowmeter according to the above-mentioned Japanese Patent No. 2880150 will be described. FIG. 4 is a diagram showing a configuration of the ultrasonic vortex flowmeter, FIG. 4 (A) is a top view of a main part of the ultrasonic vortex flowmeter, and FIG. 4 (B) is FIG. 4 (A). A-
A sectional view, FIG. 4C is a diagram showing an essential part of the ultrasonic sensor mounting structure, and FIG. 4D is a BB sectional view of FIG. 4C. In the figure, 1 is an ultrasonic vortex flowmeter main body (hereinafter, referred to as a main body), 2 is an installation portion of a display device or the like provided on an upper portion of the main body 1, 3 is a flow path of the main body 1, and 4 is a main body. Connected flow tubes, 5 are vortex generators, and a and b are ultrasonic sensor units constituting a transmitter or a receiver. Ultrasonic sensor parts a and b
Have the same configuration, the following description is for one ultrasonic sensor unit, and the other is omitted.

A sensor 6 has a side surface 7 parallel to the flow path 3, an opening 8 formed in a plane perpendicular to the side surface 7, and a depth extending vertically from the opening 8. The insertion portion 9 is a step portion provided in the depth direction of the sensor insertion portion 6. 10 ′ is a surface 1 facing the side surface 7
A vibrator 12 is bonded to 1 ', and a cylindrical sensor holding member having a hollow portion formed on the side opposite to the surface 11'. 13
Is a sensor guide having a hollow portion having a U-shaped cross section, and having a fin 14. A spring 15 is mounted so that one end thereof is in contact with the bottom of the hollow portion of the sensor holding member 10 ′ and the other end is in contact with the deep portion of the hollow portion of the sensor guide 13. 10 ′, and thus the vibrator 12, is pressed against the side surface 7 of the sensor insertion part 6. The sensor guide 13 guides the ultrasonic sensor with the sensor holding member 10 ′ and the spring spring 15 inserted therein. The sensor guide 13 is provided in the step 9 of the sensor insertion section 6 through a screw hole drilled in the fin 14. The sensor holding member 10 'is screwed to hold the sensor holding member 10', thereby preventing protrusion, displacement, and the like. Reference numeral 16 denotes a lead wire for transmitting and receiving an electric signal to and from the vibrator 12.

The sensor holding member 10 ′ is inserted into the sensor insertion portion 6 through the opening 8 in a state where the sensor holding member 10 ′ is pushed into the sensor guide 13 against the urging force of the spring spring 15. By screwing the sensor, the sensor can be easily mounted and replaced.

The vibrator 12 and the sensor holding member 10 'constitute an ultrasonic sensor.
0 'was fixed directly to the surface 11' with an adhesive. However, at this time, if the vibrator 12 is too close to the surface 11 'of the sensor holding member 10', the impedance of the ultrasonic sensor tends to decrease, and the reception level of the ultrasonic sensor as a receiver tends to decrease. When the reception level decreases, the signal-to-noise ratio naturally deteriorates, and the receiver cannot reliably detect a weak ultrasonic signal that has undergone frequency modulation in proportion to the period of the vortex. It is impossible to measure. In addition, the impedance of the ultrasonic sensor has a temperature characteristic. Even if the impedance can be detected at a certain temperature, if the temperature of the fluid to be measured or the environmental temperature changes, the impedance becomes small, and the vortex cannot be detected. There was also.

Therefore, in order to increase the impedance as an ultrasonic sensor as much as possible, the adhesive is layered to have a thickness and is separated from the sensor holding member 10 'so that the vibrator 1
2 was bonded. However, it was difficult to connect each ultrasonic sensor to the impedance meter and adjust the thickness of the adhesive layer while measuring the impedance. In other words, it has been difficult to mass produce a homogeneous ultrasonic sensor having a desired value of impedance.

The present invention has been made in view of such circumstances, and provides a structure of a vibrator and a holding member for easily obtaining an ultrasonic sensor having a predetermined high impedance used for an ultrasonic flowmeter. Is what you do.

[0010]

According to a first aspect of the present invention, there is provided an ultrasonic sensor in which a disk-shaped ultrasonic vibrator is adhered to a tip of a cylindrical sensor holding member. A concave portion having a predetermined diameter and a predetermined depth smaller than the diameter of the disk-shaped ultrasonic vibrator is provided at the center of the vibrator bonding surface, the concave portion is filled with an adhesive, and the ultrasonic vibrator is placed thereon. An ultrasonic sensor characterized by being adhered and having a high impedance characteristic with a very simple configuration.

According to a second aspect of the present invention, there is provided an ultrasonic flowmeter having an ultrasonic sensor for transmitting and receiving ultrasonic waves provided on a flowmeter main body including a flow path of a fluid to be measured, wherein the ultrasonic sensor is used as the ultrasonic sensor. The present invention provides an ultrasonic flowmeter having a high reception level by employing the ultrasonic sensor described in (1).

[0012]

FIG. 1 is a view showing an embodiment of an ultrasonic sensor mounting structure according to the present invention. Since the configuration other than the mounting structure is common to the conventional ultrasonic flowmeter, only the mounting configuration diagram corresponding to FIG. 2C is shown, and the same reference numerals are given to the common components.

In the figure, a sensor insertion portion 6 has a side surface 7 parallel to the flow path 3 and an opening 8 formed in a surface orthogonal to the side surface 7.
And has a depth extending vertically from the opening 8. Reference numeral 10 denotes a columnar sensor holding member in which a vibrator 12 is bonded to a surface 11 facing the side surface 7 and a hollow portion is formed on the side opposite to the surface 11. The sensor guide 13 has a hollow section having a U-shaped cross section in which the sensor holding member 10 and the spring spring 15 are inserted and guided, and is screwed to the main body 1. The spring 15 is mounted so that one end thereof is in contact with the bottom of the hollow portion of the sensor holding member 10 and the other end is in contact with the back portion of the hollow portion of the sensor guide 13.
The vibrator 12 is pressed against the side surface 7 of the sensor insertion part 6. The lead wire 16 is connected to the vibrator 12 to transmit and receive an electric signal.

The vibrator 12 of the cylindrical sensor holding member 10
The point that a concave portion 111 having a predetermined diameter and depth is provided in a central portion of a surface 11 on a side to be bonded with the vibrator 12 while leaving a peripheral portion of the vibrator 12.
0 '. Then, the vibrator 12 has its concave portion 111
Holding member 10 via adhesive 112 filled in
Adhered to. FIG. 2 is a diagram showing the frequency characteristics of the impedance of the ultrasonic sensor according to the present invention thus produced and the impedance of the conventional ultrasonic sensor. Note that the transducer and the sensor holding member use the same dimensions, and the size of the concave portion 111 of the ultrasonic sensor according to the present invention is
The diameter was 6.0 mm and the depth was 0.1 mm. As can be seen from the figure, the impedance of the ultrasonic sensor according to the present invention is higher near the operating frequency band than the conventional ultrasonic sensor. For example, the magnitude of the impedance measured at a frequency of 2.15 MHz is
The conventional one has 331 Ω, whereas the present invention shows 1.02 KΩ. Incidentally, when this ultrasonic sensor was used as a receiver, 2.15 under the same conditions
The reception level obtained by detecting the ultrasonic wave of MHz is 360 mV for the conventional one and 700 mV for the present invention.
Met. This is because the ultrasonic sensor of the present invention has the concave portion 111 on the bonding surface of the vibrator at the tip of the sensor holding member, so that the vibrator does not directly adhere to the sensor holding member and has a predetermined thickness of the adhesive. Since the 112 is bonded between the two, the completed ultrasonic sensor has a high impedance, and it is considered that a high reception output is generated as the sensor. FIG. 3 is a diagram showing the temperature characteristics of the reception level of the ultrasonic sensor according to the present invention and the conventional ultrasonic sensor. From this figure, it can be seen that in the measured temperature range, the reception output of the ultrasonic sensor according to the present invention is higher than the reception output of the conventional ultrasonic sensor in all regions, and especially in the vicinity of the operating frequency. Is remarkable.
From this, the ultrasonic sensor of the present invention can be used as an ultrasonic sensor of an ultrasonic flowmeter, although the reception output has a temperature characteristic with respect to a temperature change, but a sufficient reception output can be secured. It can be used for fluids in a wide temperature range and under a change in temperature environment.

Further, by appropriately selecting the diameter and depth of the concave portion 111, the type and material of the adhesive 112,
The impedance of the ultrasonic sensor can be adjusted to a predetermined value, and the optimum impedance can be set according to the frequency of the applied ultrasonic wave or the measurement target. Further, when the ultrasonic sensor is manufactured,
A uniform ultrasonic sensor having the same magnitude of impedance can be obtained simply by placing the vibrator 12 on the adhesive 112 and then bonding the same. It is suitable for mass production because a product that can be eliminated and has little variation in characteristics can be manufactured with high yield.

As mentioned above, only the ultrasonic sensor used in the ultrasonic vortex flowmeter has been described as an embodiment, but it goes without saying that the present invention can be applied to the ultrasonic sensor of other ultrasonic flowmeters. It is also apparent that the present invention can be applied to an ultrasonic sensor such as an ultrasonic liquid level gauge and an ultrasonic probe.

[0017]

According to the first aspect of the present invention, the sensor holding member for holding the ultrasonic vibrator has a simple configuration in which a concave portion is provided on the vibrator bonding surface, and has a relatively high impedance of a desired size. An ultrasonic sensor having uniform characteristics can be easily obtained. When used as a receiver, a high reception level can be obtained, and a sufficient reception level can be obtained even for a wide range of temperature changes.

According to the second aspect of the present invention, by applying the ultrasonic sensor according to the first aspect to an ultrasonic flowmeter, a good flow rate signal having a high S / N reception level can be obtained. Further, it is possible to provide an ultrasonic flowmeter that does not become undetectable even when the temperature of the fluid to be measured changes.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the structure of an ultrasonic sensor according to the present invention.

FIG. 2 is a diagram illustrating frequency characteristics of reception levels of the ultrasonic sensor of the present invention and a conventional ultrasonic sensor.

FIG. 3 is a diagram showing temperature characteristics of reception levels of the ultrasonic sensor of the present invention and a conventional ultrasonic sensor.

FIG. 4 is a view for explaining a conventional ultrasonic vortex flowmeter and its ultrasonic sensor structure.

[Explanation of symbols]

1 ... Ultrasonic vortex flowmeter main body 2 ... Installation part of display device etc.
3 ... flow path, 4 ... flow pipe, 5 ... vortex generator, 6 ... sensor insertion section, 7 ... side face of sensor insertion section, 8 ... opening, 9 ... step section, 1
0, 10 ': sensor holding member, 11, 11': vibrator bonding surface, 111: concave portion, 112: adhesive, 12: vibrator,
13: sensor guide, 14: fin, 15: spring spring, 16: lead wire, a, b: ultrasonic sensor unit.

Claims (2)

[Claims] 1. An ultrasonic sensor in which a disc-shaped ultrasonic transducer is bonded to the tip of a cylindrical sensor holding member, wherein the disc-shaped ultrasonic transducer is attached to the center of the ultrasonic transducer bonding surface of the sensor holding member. An ultrasonic sensor comprising: a concave portion having a predetermined diameter and a predetermined depth smaller than the diameter of the ultrasonic vibrator; an adhesive filled in the concave portion; and the ultrasonic vibrator is bonded thereon. 2. An ultrasonic flowmeter having an ultrasonic sensor for transmitting and receiving ultrasonic waves provided in a flowmeter main body including a flow path of a fluid to be measured, wherein the ultrasonic sensor is used as the ultrasonic sensor.
An ultrasonic flowmeter characterized by employing the ultrasonic sensor described in (1).