CN2597950Y - A fixed self-damping differential flow sensor - Google Patents

Abstract

The fixed self-damping differential flow sensor of the utility model includes detection units symmetrically fixed on both sides of the plate, each detection unit includes a shell, and the shell has a through hole parallel to the axis m-m of the plate, and there is a hole in the middle of the through hole A boss that divides the through hole into upper and lower symmetrical sections. The two ends of the through hole are respectively sealed by elastic diaphragms. Each section has a piezoelectric ceramic piece and a piezoelectric ceramic piece sandwiched between the boss and the piezoelectric ceramic piece. In the insulating mass block, one end of the piezoelectric ceramic sheet is fixed to the elastic membrane, and the lead wires of the upper and lower piezoelectric ceramic sheets are connected and drawn out from the outlet hole of the plate. This kind of sensor has high measurement sensitivity, and it can still give a strong detection signal by using the differential principle when the flow is small. Its internal structure has a self-vibration damping function, strong anti-interference and large range. High reliability.

Description

A fixed self-damping differential flow sensor

Technical field

The utility model relates to a flow sensor, in particular to a self-damping differential flow sensor.

Background technique

In the late 1960s, new instruments that applied the principle of fluid vibration to measure flow appeared successively. For example, vortex flowmeters, jet flowmeters, and vortex precession flowmeters all belong to liquid vibration flowmeters. They pass heat-sensitive, strain, Flow sensors with detection methods such as capacitance and ultrasonic waves can detect fluid vibration frequency signals that are proportional to volume flow. For vibrating flow sensors, the vibration problem is an important indicator to measure the industrial application of a vibrating flow meter. Vibration in industry is ubiquitous, such as speed pulsation and fluid oscillation in fluid turbulence, and random factors such as industrial pipeline vibration, valve opening and closing, and valve core vibration, which will cause great noise to the detected frequency signal interference. At present, the more advanced vibration flow sensors have certain anti-vibration capabilities. However, the detection elements of these sensors are all fixed on the pipe wall, and the ability to resist pipeline vibration is limited. In addition, for the interference of fluid vibration, when the vibration direction of the vibration noise is parallel to the vibration direction of the measured frequency signal (that is, vibrating in the same direction), the anti-interference ability of these flow sensors is relatively weak, and the output signal will be mixed with a lot of noise. This phenomenon is especially obvious when measuring small flow rates.

Contents of Invention

The purpose of the utility model is to provide a fixed self-damping differential flow sensor with high measurement sensitivity and strong anti-interference.

The fixed self-vibration differential flow sensor of the utility model includes detection units symmetrically fixed on both sides of the plate, each detection unit includes a shell, and the shell has a through hole parallel to the axis m-m of the plate, and there is a handle in the middle of the through hole The through hole is equally divided into upper and lower two symmetrical sections of the boss, the aperture of the two symmetrical sections is larger than the aperture of the boss, there is a channel at the boss to communicate with the axial outlet hole of the plate, and the two ends of the through hole are respectively elastic diaphragms Sealing, there are piezoelectric ceramic sheets and annular insulating mass blocks in each section, one end of the piezoelectric ceramic sheet is fixed with the elastic diaphragm, the insulating mass block is sandwiched between the boss and the piezoelectric ceramic sheet, the piezoelectric ceramic sheet and the insulating mass There is a gap between the periphery of the quality block and the wall of the through hole, and the lead wires of the upper and lower piezoelectric ceramic sheets are connected and drawn out from the outlet hole of the plate through the channel.

The sensor of the utility model has high measurement sensitivity, and can still give a strong detection signal by using the differential principle when the flow rate is small. Its internal structure has a self-damping function, and it has strong anti-interference and large range range, high reliability.

Description of drawings

Fig. 1 is the axial semi-sectional view of the fixed self-damping flow sensor of the present invention;

Fig. 2 is the application schematic diagram of the utility model in the vortex flowmeter;

Fig. 3 is a schematic diagram of the application of the utility model in a vortex precession flowmeter.

Detailed ways

Referring to Fig. 1, the fixed self-damping flow sensor of the present invention includes detection units symmetrically fixed on both sides of the flat plate 6, each detection unit includes a housing 5, in order to obtain a more stable signal, a semi-cylindrical housing is generally used, The housing 5 has a through hole 7 parallel to the axis m-m of the plate. There is a boss in the middle of the through hole 7 that divides the through hole into two symmetrical sections up and down. The apertures of the two symmetrical sections are larger than the diameter of the boss. A channel 8 communicates with the axial outlet hole 4 of the flat plate, and the two ends of the through hole 7 are respectively sealed by an elastic diaphragm 1, and each section has a piezoelectric ceramic sheet 3 and an annular insulating ceramic block 2, and the piezoelectric ceramic sheet One end of one end is welded with the elastic diaphragm 1, and the insulating ceramic block 2 is sandwiched between the boss and the piezoelectric ceramic sheet, and there is a gap between the piezoelectric ceramic sheet 3 and the periphery of the insulating ceramic block 2 and the wall of the through hole. The lead wires of the upper and lower piezoelectric ceramic sheets are connected and drawn out from the plate outlet hole 4 through the channel 8 . The four piezoelectric ceramic pieces in the two detection units have the same size, quality, sensitivity coefficient, and equal pre-tightening force, and the four insulating ceramic blocks also have the same size and quality.

The concrete application of the present utility model is referring to Fig. 2, Fig. 3.

Fig. 2 is the application of the utility model in the vortex flowmeter. In order to measure the flow rate of the vibrating fluid, the fixed self-damping flow sensor B of the utility model is installed behind the vortex generator A in the vortex flowmeter. Parallel to the vortex generator; and for the vortex precession flowmeter shown in Figure 3, the fixed self-damping flow sensor should be installed at the front end of the flow channel extension, and the axis m-m of the sensor plate is perpendicular to the axis of the pipe.

During operation, the entire sensor is immersed in the fluid. When the vortex flows through the sensor, the alternating pressure generated by the vortex directly acts on the elastic membranes of the two detection units, causing the piezoelectric ceramic sheet to generate alternating charges. At this time, the two detection units will output regular sinusoidal signals S1 and S2. The frequency of these two signals is equal and the phase difference is 180°. When using the differential output, a stronger detection signal can be obtained.

When the fluid oscillates due to random factors such as pipeline vibration and valve opening, it will cause the elastic diaphragm or the sensor housing to generate following vibration. This makes the upper and lower symmetrical piezoelectric ceramics in the detection unit be pressed and pulled respectively, so the two piezoelectric ceramics will generate equal positive and negative charge signals, and when the signals of the upper and lower piezoelectric ceramics are in phase Over time, the charge signals generated by the disturbing vibration will cancel each other out, so the sensor acts as a self-damping vibration.

In addition, for the sensor of the utility model, the pipeline vibration belongs to the same direction vibration, and the sensor uses two detection units for differential detection, so the interference signals of the same direction vibration will cancel each other in the output signal S1-S2, so It can effectively eliminate the interference of pipeline vibration on the detection signal. For the fluid vibration caused by fluid pulsation, it is a series of plane waves propagating with the flow direction in the pipeline, and the pressure caused by it acts on the two detection units of the sensor in the same direction at the same time, which belongs to the same direction vibration interference. Similarly, the differential detection principle of the sensor can eliminate the interference of fluid pulsation on the detection signal. Therefore, the flow sensor of the utility model has high anti-interference performance in flow measurement. It is suitable for flow measurement of vibrating fluids such as liquid, gas and steam.

Claims (5)

1. A fixed self-damping differential flow sensor is characterized in that it includes detection units symmetrically fixed on both sides of the flat plate (6), each detection unit includes a housing (5), and the housing (5) has a m-m parallel through-holes (7), there is a boss in the middle of the through-hole (7) that divides the through-hole into two symmetrical sections up and down, the apertures of the two symmetrical sections are larger than the aperture at the boss, and there is a passage at the boss ( 8) It is connected with the axial outlet hole (4) of the plate, and the two ends of the through hole (7) are respectively sealed by elastic diaphragms (1), and there are piezoelectric ceramic sheets (3) and annular insulating masses in each interval. block (2), one end of the piezoelectric ceramic sheet is fixed to the elastic diaphragm (1), the insulating mass block (2) is sandwiched between the boss and the piezoelectric ceramic sheet, the piezoelectric ceramic sheet (3) and the insulating mass block (2 There is a gap between the periphery of ) and the wall of the through hole, and the lead wires of the upper and lower piezoelectric ceramic sheets (3) are connected and drawn out from the plate outlet hole (4) through the channel (8). 2. The fixed self-vibration differential flow sensor according to claim 1, characterized in that said insulating mass (2) is an insulating ceramic block. 3. The fixed self-damping differential flow sensor according to claim 1, characterized in that the four piezoelectric ceramic sheets (3) in the two detection units have the same size, quality and sensitivity coefficient. 4. The fixed self-vibration differential flow sensor according to claims 1 and 2, characterized in that the four masses (2) in the two detection units have the same size and quality. 5. The fixed self-vibration differential flow sensor according to claim 1, characterized in that said housing (5) is semi-cylindrical.

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