CN103674134B - A kind of ultrasound transducer apparatus - Google Patents

Abstract

An ultrasonic transducer device, comprising two crank arms, a crank spring, and two ultrasonic transducers, the middle of the two crank arms is provided with a rotating shaft, the two crank arms are divided into left and right parts by the rotating shaft, and the crank spring is arranged on Between the right halves of the two crank arms; the left ends of the two crank arms are connected to an ultrasonic transducer, and the two ultrasonic transducers are set according to the upper and lower positions, which are respectively the upper ultrasonic transducer and the lower ultrasonic transducer The upper and lower ultrasonic transducers are arranged symmetrically; the invention can be adjusted arbitrarily according to the diameter of the inner cooling water pipe, can better contact the water pipe, and can be fixed more firmly so that it does not change with the vibration of the test pipe and the external conditions And activities, it is not easy to slip and cause the ultrasonic signal strength to attenuate or even lose.

Description

An ultrasonic transducer device

technical field

The invention relates to a test device for measuring liquid flow, in particular to a test device for measuring cooling water flow in generator stator windings.

Background technique

At present, the bottom contact surface of ultrasonic transducers manufactured by domestic manufacturers is flat, which is better for measuring the signal strength of pipelines with large, smooth and small curvature, and can measure data quickly and accurately. However, in the field test of measuring the internal cooling water flow of the generator, the diameter of the internal cooling water pipe of the generator stator winding is relatively small, and the outer surface of the water pipe is relatively smooth. On both sides of the measured water pipe. Due to human factors or environmental factors, the ultrasonic transducer slips on the pipe wall, or the coupling agent applied on the contact surface of the transducer is uneven, which may easily cause serious attenuation of the measurement signal strength, loss of the signal midway, and the measurement data process is very slow or even the data lost. In addition, the space inside the generator outlet terminal box is narrow, and the water pipes in the box are mostly arc-shaped, and the straight parts of the water pipes are relatively short. It is inconvenient to set the signal collection position of the transducer, which is unavoidable in the actual measurement on site. The key to the measurement is that the ultrasonic transducer can transmit the acoustic wave signal accurately and stably, but as far as the current situation is concerned, there is no device in the domestic and foreign related ultrasonic transducer devices that can realize the signal through good fixation and contact. Stable transmission, which caused serious interference to the use of test personnel.

Contents of the invention

The object of the present invention is to provide an ultrasonic transducer device for measuring the flow of cold water in the generator stator winding, which can be adjusted arbitrarily according to the diameter of the water pipe, and can be fixed more firmly so that it does not follow the vibration of the test pipe and the external environment. It can collect ultrasonic reflection signals more effectively and achieve the best match between signal and transmission ratio faster.

Technical scheme of the present invention is:

An ultrasonic transducer device, comprising two crank arms, a crank spring, and two ultrasonic transducers, the middle of the two crank arms is provided with a rotating shaft, and the two crank arms are divided into left and right parts by the rotating shaft, and the crank spring is arranged on Between the right halves of the two crank arms; the left ends of the two crank arms are connected to an ultrasonic transducer, and the two ultrasonic transducers are set according to the upper and lower positions, which are respectively the upper ultrasonic transducer and the lower ultrasonic transducer The upper and lower ultrasonic transducers are symmetrically arranged; the ultrasonic transducer includes a shell and several transducer units located in the shell, and the transducer unit includes a piezoelectric wafer, a sound-transmitting wedge, a compression spring, and a sound-transmitting The bottom surface of the wedge is an arc surface, and the arc surface of the transducer unit faces inward and is distributed along the circumferential direction. The arc surfaces of the sound-transmitting wedges on the upper and lower ultrasonic transducers are symmetrical about the center; the piezoelectric wafer and There is an impedance matching layer between the sound-transmitting wedges; the upper side of the sound-transmitting wedge has a triangular cross-sectional shape, the piezoelectric wafer is located at the back of the sound-transmitting wedge, and the compression spring is located at the front of the sound-transmitting wedge and leans against the On the front side of the sound-transmitting wedge, the upper end of the compression spring leans against the inner side of the shell, and the compression spring is perpendicular to the direction of the ultrasonic longitudinal wave. There is also a backing material filled between the piezoelectric wafer and the housing, and the rear side of the piezoelectric wafer is A high-voltage pulse generator circuit is connected through a cable.

The number of sound-transmitting wedges is three, and the three sound-transmitting wedges are equidistantly arranged symmetrically. When the compression springs pressed against the three sound-transmitting wedges are compressed to the maximum, there is a distance between the three sound-transmitting wedges.

Including the crank sleeve, the ultrasonic transducer and the crank arm are connected through the crank sleeve.

The extension direction of the crank sleeve is perpendicular to the symmetrical center line of the upper ultrasonic transducer and the lower ultrasonic transducer.

The piezoelectric wafer is a thin disc type, using lead zirconate titanate material.

The radius of curvature of the bottom arc surface of the sound-transmitting wedge is 15 mm.

The matching element of the impedance matching layer is an inductor.

The thickness of the impedance matching layer is 1/4 of the ultrasonic wavelength.

The backing material is silica gel or epoxy resin.

The shell is made of aluminum material.

The invention is a novel ultrasonic transducer for measuring the flow of cooling water in the stator winding of a generator, and its beneficial effects are:

(1) The present invention can be adjusted arbitrarily according to the diameter of the inner cooling water pipe, can better contact the water pipe, can be fixed more firmly so that it does not move with the vibration of the test pipe and changes in external conditions, and is not easy to slip and cause ultrasonic waves Situations where signal strength is attenuated or even lost.

(2) The combined structure of 3 piezoelectric wafers arranged side by side and the sound-transmitting wedge can collect ultrasonic reflection signals more effectively, and the ultrasonic transducer can achieve the best match between signal and transmission ratio faster.

(3) When using the adhesive, it can make the contact surface of the ultrasonic transducer and the outer surface of the water pipe more uniform, better eliminate the influence of air, and improve the penetration ability of ultrasonic waves. It will help the test personnel to measure the value of the cooling water flow in the stator winding of the generator faster and more accurately.

(4) The fixed crank on the rear side of the ultrasonic transducer can fix the transducer on the inner cooling water pipe, which greatly saves the workload of the test personnel.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Fig. 2 is the structural representation of upper ultrasonic transducer;

Fig. 3 is the structural representation of transducer unit;

Fig. 4 is a schematic structural view of the present invention for the first water pipe with a smaller diameter (about 15mm);

Fig. 5 is a schematic diagram of the structure of the present invention when it is used for a second water pipe with a larger diameter (about 30mm);

Fig. 6 is a schematic diagram of the time difference method for measuring fluid flow;

Fig. 7 is a structural schematic diagram with the bottom of the ultrasonic transducer probe as a plane;

Fig. 8 is the schematic diagram when testing with the present invention;

Fig. 9 is a structural schematic diagram of an arc-shaped surface at the bottom of the ultrasonic transducer probe;

Fig. 10 is a structural diagram of an ultrasonic transmitting circuit, in which P represents a piezoelectric chip.

Numbers in the figure: 1 piezoelectric chip, 2 acoustic wedge, 3 compression spring, 4 backing material, 5 cable, 6 aluminum shell, 7 crank sleeve, 8 crank arm, 9 crank spring, 10 impedance matching layer, 11 The first water pipe with a smaller diameter (about 15mm), 12 The second water pipe with a larger diameter (about 30mm), 13 Upper ultrasonic transducer, 14 Lower ultrasonic transducer, 15 Shaft, 16 Energy conversion device unit.

detailed description

As shown in Figures 1, 2, and 3, the present invention includes two crank arms 8, crank springs 9, an upper ultrasonic transducer 13, and a lower ultrasonic transducer 14. The middle parts of the two crank arms 8 are provided with a rotating shaft 15, and the two Two crank arms 8 relatively open and close around the rotating shaft 15, and the crank spring 9 for resetting is located between the right halves of the two crank arms 8. The left ends of the two crank arms 8 are respectively connected to two crank sleeves 7, and the two crank sleeves 7 are connected to the upper ultrasonic transducer 13 and the lower ultrasonic transducer 14 respectively, and the upper ultrasonic transducer 13 and the lower ultrasonic transducer 14 have a structure Same and set symmetrically about the centerline. The upper ultrasonic transducer 13 includes three transducer units 16 , and the transducer units 16 include a piezoelectric chip 1 , a sound-transmitting wedge 2 , and a compression spring 3 .

The piezoelectric wafer 1 is made of lead zirconate titanate material, and the piezoelectric wafer 1 is in the shape of a thin disc, vibrating along the thickness direction, and the ultrasonic waves generated are longitudinal waves.

The piezoelectric chip 1 is put into the rear side of the sound-transmitting wedge 2 at a suitable angle. There is an impedance matching layer 15 between the piezoelectric chip 1 and the sound-transmitting wedge 2. The matching element of the impedance matching layer 15 is an inductance, which can improve emission, The electromechanical coupling performance between the receiving circuit and the piezoelectric transducer chip, the thickness of the impedance matching layer 15 is 1/4 of the ultrasonic wavelength, and the acoustic impedance transition between the transducer piezoelectric chip 1 and the sound-transmitting wedge 2 can be realized .

The sound-transmitting wedge 2 is made of plexiglass or rubber material. The upper cross-section of the sound-transmitting wedge 2 is triangular in shape, and the bottom is arc-shaped. There is a compression spring 3 at the front end of the wedge 2, and the compression spring 3 is perpendicular to the direction of the ultrasonic longitudinal wave, so that the ultrasonic transducer 10 can be stretched and adjusted with the change of the diameter of the water pipe. The force is perpendicular to the direction of the ultrasonic waves, so they do not interfere with each other and have no effect on the measurement data.

The backing material 4 filled with the piezoelectric wafer 1 is made of silica gel or epoxy resin, which is a high-impedance, high-attenuation sound-absorbing material. The backing material 4 can be mixed with tungsten powder with a larger particle size to make the backing have a higher Acoustic impedance, increasing the backing damping, can absorb the ultrasonic radiation radiated from the back of the piezoelectric transducer wafer and convert it into heat energy, reducing the interference caused by the back radiation. The rear side of the piezoelectric chip 1 is connected to the high-voltage pulse generator circuit through a cable 5 . The entire ultrasonic transducer is wrapped with an aluminum casing 6 . The cable 5 can adopt a three-core coaxial cable, which is led out from the rear side of the backing material 4 module and collected inside the crank sleeve 7 . The crank sleeve 7 is made of aluminum, and is fixed on the rear side of the aluminum housing 6 by screws to connect the crank arm 8 .

The crank arm 8 is a hard plastic with a cavity inside, which is convenient for the cable 5 to be connected to the flowmeter measuring instrument through the crank arm 8, and a crank spring 9 is fixed behind the crank arm 8, so that the entire ultrasonic transducer is fixed on the water pipe for stable collection Signal.

The three sound-transmitting wedges 2 are arranged equidistantly and symmetrically, and when the compression spring 3 is compressed to the maximum, the three sound-transmitting wedges 2 can achieve effective combination without contacting each other.

The crank sleeve 7 should be fixed on the rear side of the aluminum housing 6 by screws, and should not be affected by the space of the water pipe gap during measurement, and should be horizontal and vertical to the measured water pipe.

The telescopic direction of the crank spring 9 should always be kept perpendicular to the piezoelectric wafer 1, that is, parallel to the direction of the ultrasonic wave generated by the piezoelectric wafer 1. Chip 1 can always transmit and receive ultrasonic signals correctly.

As shown in Figure 6, the principle of the time difference method to measure fluid flow is to use the characteristics of different propagation speeds due to different fluid flow directions when sound waves propagate in the fluid to calculate the velocity and flow of fluid flow.

Assuming that the speed of sound in the static fluid is c, and the fluid flow velocity is v, the upper ultrasonic transducer 13 and the lower ultrasonic transducer 14 are installed on both sides of the water pipe, the axial distance between the two transducers is d, and the connecting line and The axis of the conduit is installed at an angle θ, and the distance between the transducers is L.

When launching from A1 to A2 downstream, the propagation time t1 of the sound wave is:

①t1=L/(c+vcosθ);

When launching countercurrently from A2 to A1, the propagation time t2 of the sound wave is:

②t2=L/(c-vcosθ);

Generally c>>v, the time difference is:

③Δt=t1-t2=2Lvcosθ/c2;

According to formula (3), the speed v can be obtained:

④V=L2(t1-t2)/2dt1t2;

As shown in Figure 7, the bottom contact surface of the ultrasonic transducer probe is designed as a plane.

As shown in Figures 8 and 9, if the contact surface at the bottom of the ultrasonic transducer probe is designed to be arc-shaped, the transducer will transmit and receive ultrasonic waves when it is working. Assuming that the speed of sound in the static fluid is c, and the fluid flow velocity is v, the upper ultrasonic transducer 13 and the lower ultrasonic transducer 14 are installed on both sides of the pipe, and the axial distance between the two transducers is d', and the connecting line and The axis of the conduit is installed at an angle θ', and the distance from the transducer is L'.

When transmitting downstream from the upper ultrasonic transducer 13 to the lower ultrasonic transducer 14, the propagation time t'1 of the sound wave is:

⑤t'1=L'/(c+vcosθ');

When launching countercurrently from A2 to A1, the propagation time t'2 of the sound wave is:

⑥t'2=L'/(c-vcosθ');

Generally c>>v, the time difference is:

⑦Δt'=t'1-t'2=2L'vcosθ'/c2;

According to formula (3), the velocity v' can be obtained:

⑧v'=L'2(t'1-t'2)/2d't'1t'2;

Comparing the working conditions of the two ultrasonic transducers, when the ultrasonic transducers are arranged in the same position outside the inner cooling water pipe, L=L', rotate the ultrasonic wave L' centered on the center of the inner cooling water pipe, and the contact surface of the ultrasonic transducer No matter how it rotates within the range, the angle between the fluid flow velocity v and L' is always θ, that is, θ'=θ, then it can be seen from formula ⑤ to formula ⑧ that the new ultrasonic transducer will not be affected when measuring the fluid flow rate, and The situation is the same when the contact surface is flat, that is, Δt'=Δt and v=v'.

As shown in FIG. 10 , the structure diagram of the ultrasonic transmitting circuit, in the ultrasonic transmitting circuit, three piezoelectric wafers 1 are connected in parallel and then connected to the high-voltage pulse generator. The algorithm uses the arithmetic mean of the three groups of signals, that is, v''=(v1+v2+v3+...vn)/n.

Example:

As shown in Figures 4 and 5, first apply the coupling agent evenly on the arc-shaped bottom surfaces of the three sound-transmitting wedges 2, and fix the ultrasonic transducer 10 through the crank arm 8 to the inner cooling water pipe - the first water pipe 11 Or on the second water pipe 12 position. According to the pipe diameter size of the first water pipe 11 or the second water pipe 12, the positions of the three sound-transmitting wedges 2 in the ultrasonic transducer 10 can be adjusted accordingly, but always keep the same position as the first water pipe 11 or the second water pipe 12. Maximum contact with pipe wall surfaces. Finally, turn on the power and turn on the flowmeter device for testing.

The above specific embodiments are used to illustrate the present invention, rather than to limit the present invention. Within the spirit of the present invention and the protection scope of the claims, any modification and change made to the present invention will fall into the protection scope of the present invention.

Claims (10)

1. A kind of ultrasonic transducer device, it is characterized in that: comprise two crank arms, crank spring, two ultrasonic transducers, the middle part of two crank arms is provided with rotating shaft, and two crank arms are divided into left and right two with rotating shaft. part, the crank spring is set between the right halves of the two crank arms; the left ends of the two crank arms are connected to an ultrasonic transducer, and the two ultrasonic transducers are set according to the upper and lower positions, respectively for the upper ultrasonic transducer The upper and lower ultrasonic transducers are arranged symmetrically; the ultrasonic transducer includes a housing and several transducer units located in the housing, and the transducer units include piezoelectric wafers and sound-transmitting wedges. , compression spring, the bottom surface of the sound-transmitting wedge is an arc-shaped surface, the arc-shaped surface of the transducer unit faces inward and is distributed along the circumferential direction, and the arc-shaped surface of the sound-transmitting wedge on the upper and lower ultrasonic transducers is about the center Symmetrical; there is an impedance matching layer between the piezoelectric chip and the sound-transmitting wedge; the upper side of the sound-transmitting wedge has a triangular cross-sectional shape, the piezoelectric chip is located at the back of the sound-transmitting wedge, and the compression spring is located at the side of the sound-transmitting wedge The front side leans against the front side of the sound-transmitting wedge, the upper end of the compression spring leans against the inner side of the housing, the compression spring is perpendicular to the direction of the ultrasonic longitudinal wave, and a backing material is also filled between the piezoelectric wafer and the housing , the rear side of the piezoelectric chip is connected with a high-voltage pulse generator circuit through a cable. 2. The ultrasonic transducer device according to claim 1, characterized in that: the number of sound-transmitting wedges is three, and the three sound-transmitting wedges are equidistantly and symmetrically arranged, and are pressed against the three sound-transmitting wedges When the compression spring is compressed to the maximum, there is a distance between the three sound-transmitting wedges. 3. The ultrasonic transducer device according to claim 1 or 2, characterized in that it comprises a crank sleeve, and the ultrasonic transducer and the crank arm are connected through the crank sleeve. 4. The ultrasonic transducer device according to claim 3, characterized in that: the extension direction of the crank sleeve is perpendicular to the center line of symmetry of the upper ultrasonic transducer and the lower ultrasonic transducer. 5. The ultrasonic transducer device according to claim 1 or 2, characterized in that: the piezoelectric wafer is a thin disc type and is made of lead zirconate titanate. 6. The ultrasonic transducer device according to claim 1 or 2, characterized in that: the curvature radius of the bottom arc surface of the sound-transmitting wedge is 15mm. 7. The ultrasonic transducer device according to claim 1 or 2, characterized in that: the matching element of the impedance matching layer is an inductor. 8. The ultrasonic transducer device according to claim 1 or 2, characterized in that the thickness of the impedance matching layer is 1/4 of the ultrasonic wavelength. 9. The ultrasonic transducer device according to claim 1 or 2, characterized in that: the backing material is silica gel or epoxy resin. 10. The ultrasonic transducer device according to claim 1 or 2, characterized in that: the housing is made of aluminum.