JP4582011B2 - Ultrasonic flow meter - Google Patents

Description

  The present invention relates to an ultrasonic transducer that transmits and receives ultrasonic pulses and an ultrasonic flowmeter that measures the flow rate and flow velocity of gas and liquid using the ultrasonic transducer.

Conventionally used as a fixture of this type of ultrasonic transducer is provided with an insulating portion 27 provided with connection terminals 26a, 26b on a positioning body 25 as shown in FIG. 7, and a terminal 29a of an ultrasonic transducer 28. , 29b are electrically connected to the connection terminals 26a, 26b. The positioning body 25 is fixed to the fluid passage wall 30 with screws or the like. Further, as shown in FIG. 8, the fixed body 31 is provided with an extraction hole 32 through which the terminals 29a and 29b of the ultrasonic transducer 28 do not contact, and is fixed to the fluid passage wall 30 with screws or the like ( For example, see Patent Document 1).
JP-A-11-325992

  However, since the terminals 29a and 29b and the connection terminals 26a and 26b penetrate the positioning body 25 and the fixed body 31 in the above-described conventional configuration, the terminals are not completely independent at the penetrated portion. For this reason, an electrical short circuit may occur due to disturbance factors such as a conductor. Further, since the terminals 29a and 29b and the connection terminals 26a and 26b are longer than the positioning body 25 and the fixed body 31, there is a problem that the terminals 29a and 29b are deformed by an external impact. Furthermore, since the fixing body 31 is provided with the extraction holes 32 that allow the terminals 29a and 29b to pass therethrough, there is also a problem that the rotation angle of the ultrasonic transducer 28 cannot be fixed.

  In the present invention, the above-mentioned problems are solved, and it is possible to achieve a stable electrical connection by protecting the electrode pins of the ultrasonic transmitter / receiver from disturbance factors with the fixture of the ultrasonic transmitter / receiver. It is an object of the present invention to provide an ultrasonic transmitter / receiver having a highly reliable mounting structure and an ultrasonic flowmeter using the ultrasonic transmitter / receiver.

In order to solve the above problems, the present invention includes a flow rate measurement unit through which a fluid to be measured flows, a pair of ultrasonic transducers provided in the flow rate measurement unit for transmitting and receiving ultrasonic waves, and the ultrasonic transducers. A fixture for fixing to the flow rate measurement unit; a measurement circuit for measuring a propagation time between the ultrasonic transducers; and a flow rate calculation means for calculating a flow rate based on a signal from the measurement circuit, The sonic transducer includes positive and negative electrode pins and lead wires electrically connected to the electrode pins, and the fixture is inserted with both the positive and negative electrode pins and the lead wires. insulating an opening, said cover the electrode pins of the positive electrode and the negative electrode, and a top wall covering the opening partially in order to be drawn out of the lead wire, suspended from the ceiling wall of the electrode pins of the positive electrode and the negative electrode And a protective wall It is intended.

  According to the above invention, since the positive and negative electrode pins of the ultrasonic transducer are accommodated in the space provided in the fixture, it is possible to make the conductor and shock that are disturbance factors less susceptible to electrical short circuit. Can be prevented. In addition, since the electrode pin fits in the space, the rotation direction can be regulated.

  An ultrasonic transducer fixture and an ultrasonic flowmeter using the same according to the present invention fix an ultrasonic transducer to a flow path and at the same time protect the electrode pin, Since deformation can be prevented, a highly reliable ultrasonic transducer can be obtained, and the flow measurement of the fluid to be measured can be stably measured.

In the first invention, a flow rate measurement unit through which a fluid to be measured flows, a pair of ultrasonic transducers provided in the flow rate measurement unit for transmitting and receiving ultrasonic waves, and the ultrasonic transducers are provided in the flow rate measurement unit. A fixing device for fixing, a measurement circuit for measuring a propagation time between the ultrasonic transducers, and a flow rate calculation means for calculating a flow rate based on a signal from the measurement circuit, wherein the ultrasonic transducer is The positive and negative electrode pins, and lead wires electrically connected to the electrode pins, and the fixture includes an opening into which the positive and negative electrode pins and the lead wires are inserted, and the positive electrode and covering the electrode pins of the negative electrode, and a top wall covering the opening partially in order to be drawn out of the lead wire, and a protective wall which is suspended from the ceiling wall to insulate the electrode pins of the positive electrode and the negative electrode By having the ultrasonic Receiving the electrode pin of the device to make it less susceptible to disturbance and conductors, it is possible to obtain a highly reliable ultrasonic transducer, and to stably measure the flow rate of the fluid to be measured Can do.

(Embodiment 1)
1 and 2 show a configuration diagram of an ultrasonic transducer and an ultrasonic flowmeter using the ultrasonic transducer according to the first embodiment of the present invention.

  In FIG. 1, an ultrasonic transducer 1 is equipped with a vibration propagation suppressing body 4 and a direction suppressing body 5, and is fixed to a flow path 6 with a screw (not shown) via a fixture 3. The lead wire 11 is connected to the lead wire terminals 10a and 10b with the electrode pins 2a and 2b of the ultrasonic transducer 1 by changing the direction by 90 degrees.

  FIG. 2 is a perspective view of the fixture of the ultrasonic transducer according to the first embodiment.

  The lead wire chambers 8a and 8b are constituted by protective walls 9a, 9b, 9c and 9d so as to surround the lead wire terminals 10a and 10b connected to the electrode pins 2a and 2b. The flow path 6 is fixed through screws (not shown) in the screw holes 7a and 7b.

  The operation and action of the fixture for an ultrasonic transducer configured as described above will be described below. First, the fixture 3 is made of an insulating material such as resin. Lead wire terminals 10 a and 10 b are connected to the electrode pins 2 a and 2 b of the ultrasonic transducer 1, the lead wire 11 is passed through the lead wire chambers 8 a and 8 b of the fixture 3, and the fixture 3 is illustrated in the flow path 6. Fix with screws that are not. The protective walls 9a, 9b, 9c, 9d in the fixture 3 are higher than the lead wire terminals 10a, 10b.

  As described above, in the embodiment, by making the protective walls 9a, 9b, 9c, 9d of the fixture 3 higher than the lead wire terminals 10a, 10b, it becomes difficult to short-circuit with a conductor that is a disturbance factor, Since the impact or the like is not directly received by the lead wire terminals 10a and 10b, the deformation of the lead wire terminals 10a and 10b can be prevented.

The lead wire chamber 8a in the present embodiment, 8b both protection walls 9a, 9b, 9c, 9a, 9b, but the is provided, the lead chamber 8a by the configuration, only the protective walls 9d partitioning the 8b provided By doing so, it is possible to prevent an electrical short circuit between the lead wire terminals 10a and 10b and to regulate the rotation direction of the ultrasonic transducer 1.

(Embodiment 2)
FIG. 3 is a perspective view of the fixture of the ultrasonic transducer according to the second embodiment.

  The lead wire chambers 8a and 8b are configured by protective walls 9a, 9b, 9c and 9d so as to surround the lead wire terminals 10a and 10b connected to the electrode pins 2a and 2b. A ceiling wall 12 is provided at 9d.

  The operation and action of the fixture for an ultrasonic transducer configured as described above will be described below. First, the lead wire terminals 10 a and 10 b are connected to the electrode pins 2 a and 2 b of the ultrasonic transducer 1, the lead wire 11 is passed through the lead wire chambers 8 a and 8 b of the fixture 3, and the fixture 3 is connected to the flow path 6. Secure with screws not shown. The lead wire terminals 10 a and 11 b are accommodated in a space surrounded by the protective walls 9 a, 9 b, 9 c and 9 d and the top wall 12 in the fixture 3.

As described above, in the embodiment, the lead wire terminals 10a and 10b are accommodated in the protective walls 9a, 9b, 9c, and 9d of the fixture 3 and the top wall 12, so that the conductor is directly connected to the lead wire terminal 1.
Since no contact with 0a and 10b occurs, it is difficult to cause an electrical short circuit, and an impact or the like is not directly received by the lead wire terminals 10a and 10b, so that deformation of the lead wire terminals 10a and 10b can be prevented.

(Embodiment 3)
FIG. 4 shows a cross-sectional view of the fixture of the ultrasonic transducer according to the third embodiment.

  The lead wire chambers 8a, 8b are provided with protective walls 9a, 9b, 9c, 9d and a ceiling wall 12 so as to surround the lead wire terminals 10a, 10b connected to the electrode pins 2a, 2b. A gap 13 is provided between the line terminals 10a and 10b.

  As described above, in the embodiment, by providing the gap 13 between the lead wire terminals 10 a and 10 b and the top wall 12 of the fixture 3, the lead wire terminals 10 a and 10 b do not directly touch the top wall 12. Therefore, when a liquid having conductivity such as water adheres to the top wall 12 and flows to the lead wire terminals 10a and 10b, the conductive material such as water flows into the gap between the top wall 12 and the lead wire terminals 10a and 10b due to capillary action. It is also possible to prevent the possibility of corrosion of the lead liquid terminals 10a and 10b due to the flowing of the liquid.

  As shown in the perspective view of FIG. 5, the top wall 12 is provided as a configuration, and the top wall 12 is supported by the protection walls 9a and 9c, and the protection wall 9d partitions the lead wire terminals 10a and 10b on the top wall 12. You may make it the structure provided with.

(Embodiment 4)
FIG. 6 is a block diagram showing a schematic configuration of an ultrasonic transducer fixture and an ultrasonic flowmeter using the fixture according to the fourth embodiment.

  In this embodiment, the gas to be measured is assumed to be a city gas and a household gas meter is assumed to be an ultrasonic flowmeter, and the material constituting the flow rate measurement unit 15 is an aluminum alloy die casting.

  In addition, about 500 kHz is selected as the operating frequency of the ultrasonic transducers 16 and 17. The oscillation circuit 18 is composed of, for example, a capacitor and a resistor and transmits a square wave of about 500 kHz. The drive circuit 19 drives the ultrasonic transducer 16 from the signal of the oscillation circuit 18, and the square wave is composed of a burst signal of three waves. A drive signal can be output. The measuring means uses a single-around method to improve the resolution of the measured flow rate.

  The control unit 24 outputs a transmission start signal to the drive circuit 19 and starts time measurement of the timer 22 at the same time. When receiving the transmission start signal, the drive circuit 19 drives the ultrasonic transducer 16 and transmits an ultrasonic pulse. The transmitted ultrasonic pulse propagates through the flow rate measurement unit 15 and is received by the ultrasonic transducer 17. The received ultrasonic pulse is converted into an electric signal by the ultrasonic transducer 17 and output to the reception detection circuit 21. The reception detection circuit 21 determines the reception timing of the reception signal and outputs the reception detection signal to the control unit 24. Upon receipt of the reception detection signal, the control unit 24 outputs a transmission start signal to the drive circuit 19 again after the elapse of a preset delay time td, and performs the second measurement. After repeating this operation N times, the timer 22 is stopped. The calculation unit 23 calculates the propagation time t1 by dividing the time measured by the timer 22 by the number of times N and subtracting the delay time td.

Subsequently, the ultrasonic transducer connected to the drive circuit 19 and the reception detection circuit 21 is switched by the switching circuit 20, and the control unit 24 again outputs a transmission start signal to the drive circuit 19 and simultaneously starts the time measurement of the timer 22. Contrary to the measurement of the propagation time t1, an ultrasonic pulse is transmitted by the ultrasonic transducer 17 and the measurement received by the ultrasonic transducer 16 is repeated N times, and the propagation time t2 is calculated by the calculation unit 23.

Here, the distance connecting the centers of the ultrasonic transducer 16 and the ultrasonic transducer 17 is L, the speed of sound in an air-free state is C, the flow velocity in the flow rate measurement unit 15 is V, and the flow of the non-measurement fluid And the propagation time t1, t2 are given by θ being the angle between the direction of the line and the line connecting the centers of the ultrasonic transducer 16 and the ultrasonic transducer 17.
t1 = L / (C + V cos θ) (1)
t2 = L / (C − Vcos θ) (2)
Indicated by (1) (2) to erase the sound velocity C from equation when obtaining the flow velocity V V = L / 2cosθ (1 / t1 - 1 / t2) (3)
Is obtained. Since L and θ are known, the flow velocity V can be obtained by measuring t1 and t2. If the flow velocity V and the area of the flow rate measuring unit 15 are S and the correction coefficient is K, the flow rate Q is Q = KSV (4)
It can be calculated with.

  As described above, the ultrasonic transducer fixture according to the present invention and the ultrasonic flowmeter using the fixture are electrically short-circuited by not being directly subjected to a conductor or an impact as a disturbance factor on the electrode pin. Therefore, it is possible to measure the flow rate of the fluid to be measured with high stability. Furthermore, the present invention can be applied to applications such as an ultrasonic flowmeter that measures the flow rate and flow velocity of gas and liquid by ultrasonic waves.

Configuration diagram of an ultrasonic transducer fixture according to Embodiment 1 of the present invention and an ultrasonic flowmeter using the fixture The perspective view of the fixture of the ultrasonic transducer in Embodiment 1 of this invention The perspective view of the fixture of the ultrasonic transducer in Embodiment 2 of this invention Sectional drawing of the fixture of the ultrasonic transducer in Embodiment 3 of this invention The perspective view of the fixture of the ultrasonic transducer in Embodiment 2, 3 of this invention Block diagram including a partial cross-sectional view of an ultrasonic flowmeter using the ultrasonic transducer of the present invention Configuration diagram of conventional ultrasonic transducer fixture and ultrasonic flowmeter using the fixture Configuration diagram of conventional ultrasonic transducer fixture and ultrasonic flowmeter using the fixture

DESCRIPTION OF SYMBOLS 1 Ultrasonic transducer 3 Fixing tool 8a, 8b Lead wire chamber 9a, 9b, 9c, 9d Protective wall 12 Top wall 13 Crevice

Claims (1)

A flow rate measurement unit through which the fluid to be measured flows, a pair of ultrasonic transducers provided in the flow rate measurement unit for transmitting and receiving ultrasonic waves, a fixture for fixing the ultrasonic transducers to the flow rate measurement unit, A measuring circuit for measuring a propagation time between the ultrasonic transducers; and a flow rate calculating means for calculating a flow rate based on a signal from the measuring circuit, wherein the ultrasonic transducer includes a positive electrode and a negative electrode. A pin and a lead wire electrically connected to the electrode pin, and the fixture includes an opening into which the positive and negative electrode pins and the lead wire are inserted, and the positive and negative electrode pins. covers, and having a top wall covering the opening partially in order to be drawn out of the lead wire, and a protective wall which is suspended from the ceiling wall to insulate the electrode pins of the positive electrode and the negative electrode Ultrasonic flow meter.