CN104655197A - A suspended self-damping differential flow sensor - Google Patents

Abstract

The invention discloses a suspension type self-vibration-damping differential flow sensor which comprises detection units symmetrically fixed on two sides of a flat plate, wherein each detection unit comprises a shell, the shell is provided with a through hole parallel to the axis m-m of the flat plate, the through hole is communicated with an axial wire outlet hole of the flat plate through a channel, the connecting ends of the through holes are respectively sealed by an elastic membrane, two piezoelectric ceramic pieces are arranged in the through holes, one ends of the two piezoelectric ceramic pieces are respectively fixed with the elastic membrane, the other ends of the two piezoelectric ceramic pieces are fixed with a metal block arranged between the piezoelectric ceramic pieces, gaps are reserved between the peripheries of the two piezoelectric ceramic pieces and the metal block and the wall of the through hole, and a lead of the metal block. The sensor has high measurement sensitivity, can still give a strong detection signal by using a differential principle at a small flow, and has a suspension type internal structure with strong shock resistance, a large range and high reliability.

Description

A kind of Self-vibration absorbing floating differential flow pickup

Technical field

The present invention relates to a kind of flow sensor, especially a kind of Self-vibration absorbing floating differential flow pickup.

Background technology

Latter stage in the sixties, in succession there is the Novel meter of applicating fluid vibration principle measuring flow, such as vortex shedding flow meter, fluidic flowmeter and whirlpool precession flowmeter all belong to liquid vibration formula flowmeter, they, by the flow sensor of the detection modes such as temperature-sensitive, strain, electric capacity, ultrasound wave, detect the fluid oscillation frequency signal be directly proportional for volumetric flow rate.For oscillatory type flow sensor, vibration problem is an important indicator of a measurement vibratory flowmeter commercial Application quality.Vibration in industry is ubiquitous, such as, under fluid turbulence state velocity fluctuation, fluid oscillating, and the enchancement factor such as industrial pipeline vibration, valve opening and closing and disc vibration, and this all can make the frequency signal detected be subject to great noise jamming.More advanced oscillatory type flow sensor has certain anti-vibration ability at present, but the detecting element of these sensors is all fixed on tube wall, resists the limited in one's ability of pipe vibration.In addition for the interference of fluid oscillation, when direction of vibration parallel (i.e. the in phase vibration) with institute measured frequency signal of the direction of vibration of vibration noise time, the antijamming capability of these flow sensors is all more weak, output signal can be mixed into a large amount of noises, and this phenomenon is particularly evident when Small flowrate measurement.

Summary of the invention

The object of this invention is to provide a kind of measurement sensistivity high, the Self-vibration absorbing floating differential flow pickup of strong interference immunity.

Self-vibration absorbing floating differential flow pickup of the present invention comprises the detecting unit that symmetry is fixed on dull and stereotyped two sides, each detecting unit comprises housing, housing has the through hole parallel with dull and stereotyped axis m-m, this through hole has passage to be connected with dull and stereotyped Axial-running Out string holes, company's end flexible diaphragm seal respectively of through hole, two piezoelectric ceramic pieces are had in through hole, one end of two piezoelectric ceramic pieces is fixed with flexible sheet respectively, the other end and the derby be located between piezoelectric ceramic piece are fixed, gap is left between the periphery of two piezoelectric ceramic pieces and derby and through-hole wall, the lead-in wire of derby is drawn from dull and stereotyped wire hole through passage.

Sensor of the present invention has higher measurement sensistivity, and utilize differential principle still can provide stronger detection signal when low discharge, its inner structure has from vibration-damping function, and have stronger anti-interference and relatively large journey scope, reliability is high.

Accompanying drawing explanation

Fig. 1 is the axial semisectional view of Self-vibration absorbing floating differential flow pickup

Fig. 2 is the application principle figure of the present invention in vortex shedding flow meter

Fig. 3 is the application principle figure of the present invention in whirlpool precession flowmeter

Embodiment

With reference to Fig. 1, Self-vibration absorbing floating differential flow pickup comprises the detecting unit that symmetry is fixed on dull and stereotyped 6 two sides, each detecting unit comprises housing 5, in order to obtain more stable signal, general employing semi-cylindrical shells, housing 5 has the through hole 7 parallel with dull and stereotyped axis m-m, this through hole 7 has passage 8 to be connected with dull and stereotyped Axial-running Out string holes 4, the company of through hole 7 holds flexible diaphragm 1 respectively to seal, two piezoelectric ceramic pieces 3 are had in through hole, the size of two piezoelectric ceramic pieces, quality and sensitivity coefficient are all identical, one end of two piezoelectric ceramic pieces is welded with flexible sheet 1 respectively, the other end welds with the derby 2 be located between piezoelectric ceramic piece.Such derby 2 and two piezoelectric ceramic pieces 3 form a rigid body, leave gap between the periphery of this rigid body and through-hole wall.Above-mentioned derby 2 preferably one with piezoelectric ceramic piece, there is the mass of same size.Derby 2 is simultaneously also as the output electrode of piezoelectric ceramic piece, and its lead-in wire is drawn from dull and stereotyped wire hole 4 through passage 8.Two piezoelectric ceramic pieces 3 up and down of each detecting unit must have equal pressurized pretightning force when mounted, so have the interphase of an internal stress in the rigid body that two piezoelectric ceramic pieces 3 and derby 2 form, because intermetallic metal mass 2 has certain thickness, so this stress interphase is bound to inner at metallic gauge block, and two piezoelectric ceramic pieces 3 are Striking symmetry couplings, therefore can ensure be subject to the equal masterpiece used time, these two piezoelectric ceramic pieces can produce equal electric charge.

Embody rule of the present invention is see Fig. 2, Fig. 3.

Fig. 2 is the application of the present invention in vortex shedding flow meter, and in order to the flow of measuring vibrations fluid, Self-vibration absorbing floating differential flow pickup B of the present invention is arranged in vortex shedding flow meter after eddy generator A, and sensor is parallel with eddy generator; And the whirlpool precession flowmeter shown in the Fig. 3 of opposite, Self-vibration absorbing floating differential flow pickup is arranged on runner expanding section front end, the axis m-m of sensor plate and the intersect vertical axis of pipeline.

During work, whole sensor all immerses in a fluid.When eddy-currents is through sensor, the alternating pressure that whirlpool produces acts directly on the flexible sheet of two detecting units, makes piezoelectric ceramic piece produce alternation electric charge.These two detecting units can export sinusoidal signal S1 and the S2 of rule, and these two signal frequencies are equal, phase 180 °, even when low discharge, utilize differential output can obtain stronger detection signal.

When fluid is due to the impact of the enchancement factor such as pipe vibration, valve opening, when there is fluid oscillation, flexible sheet or sensor housing can be caused to produce and to follow vibration.Due to the inertia effect of derby, laterally zygomorphic two piezoelectric ceramics sector-meetings pressurized and tension respectively in detecting unit, this makes two piezoelectric ceramic pieces produce equal positive and negative charge signal respectively, and when the signal of upper and lower two piezoelectric ceramic pieces is added in derby (electrode), interference is vibrated the charge signal produced and can be cancelled each other, thus sensor serves from damping effect.

In addition, for sensor of the present invention, pipe vibration belongs in phase vibration, and sensor is employing two detecting units carries out differential detection, therefore the undesired signal of in phase vibration can be cancelled out each other in output signal S1-S2, effectively can eliminate the interference of pipe vibration to detection signal like this.Therefore flow sensor of the present invention has very high anti-interference in flow measurement.Be applicable to liquid.The flow measurement of the vibration such as gas vapor fluid.

Claims (1)

1. A suspension type self-vibration differential flow sensor, 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 through hole parallel to the flat axis m-m 7. The through hole 7 communicates with the axial outlet hole 4 of the plate through a channel 8, and the connecting ends of the through hole 7 are respectively sealed by elastic diaphragms 1. There are two piezoelectric ceramic sheets 3 in the through hole, and two piezoelectric ceramic sheets 3 One end of the ceramic sheet is respectively fixed with the elastic diaphragm 1, and the other end is fixed with the metal block 2 arranged between the piezoelectric ceramic sheets. The lead wire of the metal block 2 is drawn out from the outlet hole 4 of the plate through the channel 8 .