CN213209155U

CN213209155U - Sensor for liquid flowmeter

Info

Publication number: CN213209155U
Application number: CN202021954608.5U
Authority: CN
Inventors: 李政达; 丁国峻
Original assignee: Unictron Technologies Corp
Current assignee: Unictron Technologies Corp
Priority date: 2020-07-06
Filing date: 2020-09-09
Publication date: 2021-05-14
Anticipated expiration: 2030-09-09
Also published as: TWM601817U

Abstract

The utility model provides a sensor for a liquid flowmeter, including a casing, have an internal surface, a piezoceramics piece has a first face and a second face, wherein first face paste in casing internal surface to and a circuit board, connect through the wire and be used for providing a drive signal and give the piezoceramics piece, wherein the circuit board has a third face and a fourth face, the third face has a ground connection contact and a negative pole electrical contact, the fourth face has a specific area's metal level, just metal level electrical connection to a ground connection contact or a negative pole electrical contact or the metal level electrical property is connected to simultaneously the ground connection contact with negative pole electrical contact.

Description

Sensor for liquid flowmeter

Technical Field

The utility model relates to a sensor, more specifically relates to a sensor for fluidflowmeter, the error noise that records when can effectively reduce liquid static.

Background

An ultrasonic sensor (ultrasonic transducer) can be used for short-distance object detection, and the distance between the ultrasonic sensor and an object to be detected can be calculated through the time difference of reflected ultrasonic waves after the ultrasonic waves collide with the object. For ultrasonic detection, the type and properties of the object to be detected are not limited too much, including various surface colors, transparency, hardness of solid, liquid, or powder, etc., which can be detected by the ultrasonic sensor. Therefore, the ultrasonic sensor is widely used in the fields of car backing radar (backing sensor), level sensor (level sensor), multiple sheet layer detection (multiple sheet detection), and flow meter (flow meter).

One of the fields of application of ultrasonic sensors is in liquid flow meters, i.e. for measuring the flow rate of a liquid. Referring to fig. 1, fig. 1 is a schematic structural diagram of a conventional liquid flow meter, and as shown in fig. 1, a liquid flow meter 10 includes a tubular structure 12, two

ultrasonic sensors

14A and 14B and two

reflectors

16A and 16B are included in the tubular structure 12, and the

ultrasonic sensors

14A and 14B are respectively connected to a processor (not shown) through wires for recording or analyzing signal data transmitted or received by the ultrasonic sensors. When one of the ultrasonic sensors (e.g., 14A) sends out an ultrasonic signal, the ultrasonic signal passes through the reflector 16A and the reflector 16B in sequence to reach the other ultrasonic sensor (e.g., 14B), so that the time taken for the ultrasonic signal to pass from the ultrasonic sensor 14A to the ultrasonic sensor 14B can be recorded, and then the ultrasonic signal is also passed from the ultrasonic sensor 14B back to the ultrasonic sensor 14A (also passing through the reflector 16B and the reflector 16A in sequence). When there is a flow of liquid in the tubular structure 12, for example, when the liquid flows from the left side to the right side of the tubular structure 12 in fig. 1, the transmission rate of the ultrasonic signal from the ultrasonic sensor 14A to the ultrasonic sensor 14B is faster because the ultrasonic signal is transmitted in the same direction as the flow of the liquid, and conversely, the transmission rate of the ultrasonic signal from the ultrasonic sensor 14B to the ultrasonic sensor 14A is slower because the ultrasonic signal is transmitted in the opposite direction to the flow of the liquid. The flow rate of the liquid can be calculated by calculating the difference between the transmission times (Time of Flight, ToF) of the two ultrasonic signals, and if the liquid flows along a specific path, the flow rate of the liquid is further multiplied by the sectional area of the flow path to obtain flow data.

From the above-described configuration, it can be seen that when the liquid in the tubular structure 12 is in a stationary state, the transmission rate of the ultrasonic signal should not change due to the flow rate of the liquid regardless of whether the ultrasonic signal is transmitted from the ultrasonic sensor 14A to the ultrasonic sensor 14B or from the ultrasonic sensor 14B to the ultrasonic sensor 14A. That is, the measured ToF difference (i.e., the difference between the transit time of the ultrasonic signal from the ultrasonic sensor 14A to the ultrasonic sensor 14B and the transit time of the ultrasonic signal from the ultrasonic sensor 14B to the ultrasonic sensor 14A) should ideally approach 0. However, in practical situations, due to environmental factors, external interference or errors in the transmission process of the electrical signal through the wires, the ToF differences still can be detected by the liquid flow meter 10 in a static state of the liquid, and these ToF differences are regarded as errors or noises of the liquid flow meter, and the larger the errors or noises are, the worse the flow rate and the flow accuracy of the liquid flow meter are calculated.

Therefore, it is an objective of the development of liquid flow meters to reduce the ToF gap that can be detected by the liquid flow meter when the liquid is at rest.

SUMMERY OF THE UTILITY MODEL

The following paragraphs provide a brief description of the invention in order to give the reader a basic understanding of the objects of the invention. This description is not intended to be an exhaustive or exhaustive list of all critical or essential elements of the invention or to limit the scope of the invention, but rather to provide a simplified representation of some concepts of the invention as discussed in more detail below.

An object of the present invention is to provide a sensor for a liquid flowmeter, including a casing, have an internal surface, a piezoceramics piece has a first face and a second face, wherein first face paste in the internal surface of casing to and a circuit board, connect through the wire and be used for providing a drive signal and give the piezoceramics piece, wherein the circuit board has a third face and a fourth face, the third face has a ground connection contact and a negative pole electrical contact, the fourth face has a specific area's metal level, just metal level electrical connection to ground connection contact or negative pole electrical contact, perhaps the metal level electrical property is connected to simultaneously ground connection contact with negative pole electrical contact.

Preferably, the ground contact is electrically connected to the metal layer through a conductive via.

Preferably, the sensor further comprises a buffer layer, and the buffer layer is located between the piezoelectric ceramic plate and the circuit board.

Preferably, the third surface of the circuit board further includes a positive electrical contact.

Preferably, the metal layer and the circuit board are formed separately and then combined with each other, and the metal layer may be independently grounded.

Preferably, the metal layer is different in shape from the circuit board.

The beneficial effects of the utility model include: by arranging the metal layer on one surface of the circuit board, and connecting the metal layer to the grounding contact or the negative electrical contact or both the grounding contact and the negative electrical contact, the interference of the sensor when a signal is transmitted to the processor can be effectively reduced, and therefore, the error value (ToF difference) detected by the liquid flowmeter in a return-to-zero state (namely when the liquid flowmeter is placed in static liquid) can be greatly reduced. Furthermore the utility model discloses can also selectively increase the buffer layer and be located between piezoceramics piece and the circuit board, consequently can further reduce liquid flowmeter at the error value of the state of returning to zero, and then improve liquid flowmeter's accuracy.

The above and other objects of the present invention will become more apparent to the reader of the detailed description of the preferred embodiment, which is set forth below in the accompanying drawings and drawings.

Drawings

The accompanying drawings are included to provide a further understanding of embodiments of the invention, and are incorporated in and constitute a part of this specification. These drawings depict some embodiments of the invention and, together with the description herein, serve to explain its principles. In the drawings:

FIG. 1 is a schematic diagram of a prior art fluid flow meter;

fig. 2 is a schematic cross-sectional view of an embodiment of a sensor for use in a fluid flow meter according to embodiments of the present invention;

fig. 3 is a schematic cross-sectional view of one embodiment of a front side of a circuit board of a sensor in accordance with embodiments of the present invention;

fig. 4 is a schematic cross-sectional view of one embodiment of a back side of a circuit board of a sensor in accordance with embodiments of the present invention;

fig. 5 is a schematic cross-sectional view of another embodiment of a back side of a circuit board of a sensor according to embodiments of the present invention;

FIG. 6 is a graphical representation of ToF error measured by a return-to-zero test performed on a prior art fluid flow meter; and

fig. 7 is a ToF error map measured by a return-to-zero test performed by a fluid flow meter according to an embodiment of the invention.

The reference numerals are explained below:

10 liquid flowmeter

12 tubular structure

14A ultrasonic sensor

14B ultrasonic sensor

16A reflector

16B reflector

20 ultrasonic sensor

22 casing

22A outer surface

22B inner surface

24 piezoelectric ceramic plate

24A first side

24B second side

26 buffer layer

28 Circuit Board

28A third face

28B fourth face

29 metal layer

30 adhesive layer

32 wire

34 waterproof packaging adhesive

(+) positive electrode electrical contact

(-) negative electrode electrical contact

(G) Grounding contact

Via Via

It should be noted that all the figures in this specification are schematic in nature, and that the components in the figures may be exaggerated or reduced in size or scale for clarity and convenience of illustration, and generally, the same reference numerals will be used to indicate corresponding or similar features in modified or different embodiments.

Detailed Description

In the following detailed description of the present invention, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific embodiments in which the embodiments may be practiced. Such embodiments will be described in sufficient detail to enable those skilled in the art to practice the invention. The dimensions of some of the elements in the figures may be exaggerated for clarity. The reader should appreciate that other embodiments may be utilized and structural, logical, and electrical changes may be made without departing from the embodiments. The following detailed description is, therefore, not to be taken in a limiting sense, and the embodiments included therein are defined by the appended claims.

For convenience of illustration, the drawings are only schematic to facilitate understanding of the present invention, and the detailed proportions can be adjusted according to design requirements. In the description herein, relative element relationships among relative elements in the drawings are described as relative positions of the elements, and thus, the relative positions of the elements should be understood by those skilled in the art to be reversed to represent the same elements, and all of the elements should be considered as falling within the scope of the disclosure, and the description thereof should be given first.

Referring to fig. 2, fig. 2 is a schematic cross-sectional view of an embodiment of a sensor applied to a liquid flowmeter according to the present invention. As shown in fig. 2, an ultrasonic sensor 20 includes a housing 22. The material of the housing 22 may include a metal material selected from the following group or a combination thereof: aluminum, titanium, copper, stainless steel, or a non-metallic material selected from the group consisting of: glass, ceramic, acryl, teflon (PTFE), polyvinylidene fluoride (PVDF), polypropylene (PP), Polyethylene (PE), polyvinyl chloride (PVC), polybutylene terephthalate (PBT), Acrylonitrile Butadiene Styrene (ABS), Polyphenylene Sulfide (PPs), Liquid Crystal Polymer (LCP), or polyether ether ketone (PEEK), etc. The casing 22 has an outer surface 22A and an inner surface 22B, and the inner surface 22B of the casing 22 at least includes a piezoceramic sheet 24, a buffer layer 26 and a circuit board 28. The piezoceramic wafer 24 has a first surface 24A and a second surface 24B, wherein the first surface 24A is adhered to the inner surface 22B of the housing 22, and a bonding layer 30 may optionally be disposed between the first surface 24A of the piezoceramic wafer 24 and the inner surface 22B of the housing 22 for securing the piezoceramic wafer 24 to the inner surface 22B of the housing 22. The adhesive layer 30 is, for example, a polymer adhesive material, but the present invention is not limited thereto, and the material of the adhesive layer may be adjusted according to actual requirements.

The buffer layer 26 is located on the second side 24B of the piezoceramic wafer 24, and the buffer layer 26 is located between the piezoceramic wafer 24 and the circuit board 28. Wherein the piezoceramic wafers 24 comprise a piezoelectric material, such as lead zirconate titanate (Pb (ZrTi) O₃) Lead titanate (PbTiO)₃) Piezoelectric material containing lead, or barium titanate (BaTiO)₃) Potassium sodium niobate ((NaK) NbO)₃) And the like, lead-free piezoelectric materials. After the piezoelectric material receives a driving signal (e.g., an ac signal), the material itself vibrates to generate ultrasonic waves. The material of the buffer layer 26 includes materials that have certain elasticity and can absorb shock, such as foam, wool felt, and rubber. In the present invention, the buffer layer 26 is disposed between the piezoelectric ceramic sheet 24 and the circuit board 28, so as to effectively reduce the transmission of the excessive vibration energy to the circuit board 28, and avoid affecting the judgment of the processor (not shown).

The circuit board 28 is disposed on the buffer layer 26 and is used for providing a driving signal, such as an ac signal, to the piezoelectric ceramic plate 24 to generate an ultrasonic signal for the piezoelectric ceramic plate 24. The plurality of wires 32 are connected to the positive electrical contact (+), the negative electrical contact (-) and the ground contact (G) of the circuit board 28, respectively, and the other end of the wires is connected to a processor (not shown) for processing, analyzing or recording the signals sent or received by the sensor 20. The wire 32 may be a metal wire having a shielding and insulating effect (e.g., a waterproof function) to prevent the liquid flow meter from being affected when placed in a liquid. In addition, a waterproof sealant 34 is preferably included in the housing 22 to cover the above components, such as the circuit board 28, so as to protect the circuit board 28 and other relatively precise components from moisture. The material of the waterproof sealing adhesive 34 is, for example, silica gel or epoxy resin, but the present invention is not limited thereto. The components such as the wires 32 or the waterproof sealant 34 are well known in the art and will not be described in detail herein.

Fig. 3, 4 and 5 may be referred to together for the structure of the circuit board 28. Fig. 3 is a schematic cross-sectional view of an embodiment of a front surface of a circuit board of a sensor according to an embodiment of the present invention, fig. 4 is a schematic cross-sectional view of an embodiment of a back surface of a circuit board of a sensor according to an embodiment of the present invention, and fig. 5 is a schematic cross-sectional view of another embodiment of a back surface of a circuit board of a sensor according to an embodiment of the present invention. As shown in fig. 3, the circuit board 28 is, for example, a PCB, which has a third surface 28A and a fourth surface 28B (or in some embodiments, the third surface 28A is defined as the front surface of the circuit board 28, and the fourth surface 28B is defined as the back surface of the circuit board), and the third surface 28A (the front surface) of the circuit board 28 includes a plurality of electrical contacts, such as a positive electrical contact (+), a negative electrical contact (-), and a ground contact (G). The fourth surface (back surface) 28B includes a metal layer 29. Referring to fig. 2 again, the circuit board 28 further includes a conductive Via penetrating the circuit board 28, and the conductive Via is connected to the ground contact (G) on the third surface 28A and the metal layer 29 on the fourth surface 28B of the circuit board 28. The positive electrode electrical contact (+), the negative electrode electrical contact (-), the ground contact (G), the metal layer 29, and the conductive Via include, for example, a conductive material such as a metal, such as copper, but the invention is not limited thereto.

In a conventional liquid flow meter, a circuit board is not provided with a ground contact, or a metal layer is not provided on the back surface of the circuit board. The utility model provides a flowmeter and current flowmeter main difference lie in, the utility model discloses a flowmeter 20 has additionally formed buffer layer 26 and has been located between piezoceramics piece 24 and circuit board 28 to and additionally increased ground connection contact (G) in the front of circuit board 28 (third face 28A), and formed metal level 29 at the back of circuit board 28 (fourth face 28B), and ground connection contact (G) and metal level 29 are through electrically conductive through-hole Via electric connection. According to the applicant's experiments, the buffer layer 26 can effectively reduce the transmission of the excessive vibration energy to the circuit board 28; the ground contact (G) on the circuit board and the metal layer 29 on the back side (the fourth side 28B) of the circuit board 28 can effectively reduce the noise generated during the transmission of the electrical signal, thereby reducing the error value of the liquid flowmeter 20. According to various embodiments of the present invention, the shape of the metal layer 29 on the fourth surface 28B of the circuit board 28 can be changed according to different requirements. For example, in fig. 4 the metal layer 29 covers almost completely the fourth face 28B of the circuit board 28, whereas in fig. 5 the metal layer 29 covers only about half the area of the fourth face 28B of the circuit board 28. Furthermore, in some embodiments of the present invention, the metal layer 29 of the fourth surface 28B of the circuit board 28 is not necessarily sheet-shaped as in this embodiment, but may also include other shapes, such as a mesh-shaped metal layer, or the metal layer of the fourth surface of the circuit board is replaced by a separate metal sheet (including other shapes). That is, the metal layer 29 may be directly formed on the fourth surface 28B of the circuit board 28 by plating or the like, or the circuit board 28 and the separate metal layer 29 may be provided separately and then bonded to each other. In this case, the circuit board 28 and the metal layer 29 are formed separately and then bonded to each other, and the metal layers 29 formed separately may be grounded independently. It is also permissible for the circuit board 28 and the metal layer 29 to have different shapes. The above embodiments are also within the scope of the present invention.

Referring to fig. 6 and 7, fig. 6 shows a return-to-zero measurement performed by a conventional liquid flowmeterThe ToF error map measured by the test, and fig. 7 is the ToF error map measured by the liquid flow meter according to the embodiment of the present invention performing a return-to-zero test. More specifically, fig. 6 and 7 show the results of the zeroing test performed on a general liquid flowmeter (i.e., without a buffer layer and with a ground contact and a back metal layer on a circuit board) and the liquid flowmeter provided by the present invention (i.e., with the buffer layer, the ground contact of the circuit board and the back metal layer) at a temperature of 25 ℃. The zeroing test described herein represents placing the fluid flow meter in a stationary fluid and then testing the ToF difference (i.e., the difference in the time that an ultrasonic signal is transmitted between two ultrasonic transducers) over a period of time. In the patterns shown in fig. 6 and 7, the horizontal axis represents elapsed time in seconds(s) and the vertical axis represents time difference in picoseconds (ps), i.e., 10^-12And second.

In addition, in addition to fig. 6 and 7, the applicant also performed multiple zeroing tests with a general liquid flowmeter and the liquid flowmeter provided by the present invention, respectively, at different ambient temperatures. The results are shown in table one below. In table one below, the Mean field represents the average number of ToF differences, the Min field represents the minimum difference of ToF, and the Max field represents the maximum difference of ToF. And σ represents the average variation value at said temperature. It is noted that the smaller the value σ, the better the result representing the zeroing of the liquid flow meter at that temperature, i.e., the more accurate the result measured by the liquid flow meter will be.

Watch 1

From the results of fig. 6 and 7 and table i, it is obvious that the sigma value of the liquid flowmeter provided by the present invention is much lower than that of the general case liquid flowmeter no matter which temperature is. Represent the utility model discloses a fluidflowmeter has set up the buffer layer and has set up ground structure on the circuit board, can reduce fluidflowmeter's average variation value when carrying out the test of returning to zero effectively really. That is to say, when the liquid flowmeter provided by the utility model is placed in a static liquid, the noise received by the processor will be obviously smaller than that of a general liquid flowmeter.

To sum up, the beneficial effects of the utility model include: by arranging the buffer layer, the grounding structure of the circuit board and the metal layer on the back of the circuit board, the problem of overlarge variation value of the ToF when a common liquid flowmeter is subjected to a return-to-zero test can be effectively solved. The experimental result shows that under various different temperatures, the average variation value of the ToF is above 80ps when the return-to-zero test is carried out on the general liquid flowmeter, and the average variation value of the ToF is below 30ps when the return-to-zero test is carried out on the liquid flowmeter of the utility model under various different temperatures. Therefore the utility model provides a liquid flowmeter, in static liquid, the noise that the treater received will obviously more general liquid flowmeter's small in noise, and then can effectively improve liquid flowmeter's accuracy.

The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made according to the claims of the present invention should be covered by the present invention.

Claims

1. A sensor for a fluid flow meter, comprising:

a housing having an inner surface;

the piezoelectric ceramic piece is provided with a first surface and a second surface, wherein the first surface is adhered to the inner surface of the shell; and

the circuit board is connected through a wire and used for providing a driving signal to the piezoelectric ceramic piece, wherein the circuit board is provided with a third surface and a fourth surface, the third surface is provided with a grounding contact and a negative electrical contact, the fourth surface is provided with a metal layer with a preset area, and the metal layer is electrically connected to the grounding contact or the negative electrical contact, or the metal layer is electrically connected to the grounding contact and the negative electrical contact at the same time.

2. The sensor of claim 1, wherein the ground contact is electrically connected to the metal layer by a conductive via.

3. The sensor of claim 1, further comprising a buffer layer between the piezoceramic wafer and the circuit board.

4. The sensor of claim 1, wherein the third side of the circuit board further comprises a positive electrical contact.

5. The sensor of claim 1, wherein the metal layer and the circuit board are separately formed and then bonded to each other, and the metal layer is independently grounded.

6. The sensor of claim 1, wherein the metal layer is a different shape than the circuit board.