DD297238A5 - FAST VOLUME TRANSMITTER - Google Patents

Abstract

The invention relates to a fast volume flow meter according to the Verdraenger- and the throttle principle, which is used to measure high-frequency Wechselvolumenstroemen, dynamic impedances and the simultaneous determination of quasi-stationary Volumenstroemen in hydraulics and pneumatics. The technical object of the invention is to develop a rapid volumetric flow meter, which is used for the pressure-free measurement of alternating volume flows, for the determination of absolute values of the volume flow with high frequencies, of dynamic impedances and for the determination of quasi-stationary volume flows by the possibility of the combination of Verdraenger and throttling principle for liquid, vapor and gaseous fluids can be used. According to the invention, the technical object is achieved in that the displacement piston consists of a displacement surface provided with recesses and guide plates are arranged on the displacement surface for guiding the displacement piston. The recesses of the Verdraengerflaeche can be either round, net or comb shaped. The Verdraengerkolben consists of a duennwandigen recessed disc, which is guided over the game Führungslamellen play, wherein the Verdraengerkolben consists of a material of low density. The Fuehrungslamellen are rod-shaped and are arranged rotationally symmetrical about the center of the leadership. However, the Führungslamellen can also have the shape of a slot beech on which the Verdraengerflaeche is arranged on one side. In the case of rotating displacement pistons, the blocking effect between inflow and outflow is achieved by means of a blocking surface likewise provided with recesses. Displacement and throttle principle; Exchange volume flow measurement; Impedance measurement; Measurement of the quasi-stationary volume flow; hydraulics; Pneumatics, pressure-free; high frequency; Fuehrungslamellen}

Description

Field of application of the invention

The invention relates to a fast volume flow meter according to the displacement and the throttle principle, which is used for the measurement of high-frequency alternating volume flows, dynamic impedances and the simultaneous determination of quasi-stationary volume flows in hydraulics and pneumatics.

Characteristic of the known state of the art

For the measurement of volume flows according to the displacement principle different Lö ments are known. In ROSTECK, F.W .: Leaks on the track, Fluid, July 1984, a leakage meter is described, which proceeds according to the displacement principle with a piston in a measuring cylinder. The movement of the piston is transmitted to an incremental encoder by a small diameter spring steel wire. The measuring cylinder is connected via connections for the Fluidein- and fluid outlet with the DUT. The piston is loaded on one side with the measuring pressure. When leakage occurs, the piston is moved in the measuring cylinder, wherein the piston stroke via the incremental encoder generates a proportional number of pulses and the piston speed of the output frequency is proportional. The solution described has the disadvantage that the relatively large and inert mass of the displacer, d. H. of the piston, and the friction of the piston allows transient volumetric flow measurements only at very low frequencies. Furthermore, external leaks occur, especially at high pressures, so that small volume flows can not be measured at high pressures. Small volume flows can be due to the relatively large friction of the piston within the measuring cylinder and the Meßwertübertragungssystems without stickslip effect statically imprecise and unsteady measure at all. In addition, different designs of measuring cylinder and piston are required for different volume flow and pressure ranges. In DD-PS 261425 a volumetric flow meter is described according to the displacement principle, which is used in particular for the transient measurement of the flow rates of gaseous and liquid fluids in a large volume flow and pressure range. This volumetric flow meter also consists of a arranged in a measuring cylinder piston, but which has the shape of a disc whose outer dimension is significantly smaller than the inner dimension of the measuring cylinder and both sides of the disc guide pieces are arranged whose outer dimension is also smaller than the inner dimension of the guides. The disc is thin-walled in this case and the external dimension of the disc is opposite to the stroke of the disc and the surface of the disc is compared to the sum of the area of flow area of the openings and flow area, which is formed by the macro-gap between the guide and the guide piece, large. This volumetric flow meter allows the determination of rapidly changing absolute values of the volumetric flow with high accuracy. The disadvantage of this solution, however, is that valves are required for switching this volume flow transmitter to move the piston for a new measurement back to its original position. The volume flow sensor described has a large length and can only be used up to certain frequencies. For measurements according to the throttle principle, this solution is not suitable.

In DE-OS 2403911 a pendulum-acting throttle for Druchfluß- and flow measurements is described. However, this damper has the disadvantage that it is not applicable to high frequencies and impedance measurement.

Object of the invention

The aim of the invention is to expand the field of application of volumetric flowmeters by the combination of positive displacement and throttling principle and an improved dynamics with simple means for the measurement of high-frequency alternating volume flows, of dynamic impedances and quasi-stationary volumetric flows.

Explanation of the essence of the invention

It is the technical object of the invention to develop a fast volumetric flow meter which measures the exchange pressure for the pressure reversal element, for the determination of absolute WeMo of the volume flow with high frequencies, of dynamic impedances and for the determination of quasi-stationary volumetric flows through the possibility of the combination of displacer · And throttling principle Can be used in liquid, vapor and gaseous flutes. According to the invention, the technical object is achieved in that the displacer piston consists of a displacement surface provided with recesses and are arranged to guide the displacer one or two sides on the displacement surface guide blades. The recesses of the displacer surface can preferably be round or mesh or 1 mm thick. The displacer piston consists of a thin-walled recessed disc or plate, which represents the recessed displacer surface, and which are guided playfully over the guide blades, wherein the displacer consists of a low-density Mateiial. The guide blades are rod-shaped and they are rotationally symmetrical about the center with the moving disc and with rotating displacement surface radially fixed to the moving plate with axially displaced displacement surface.

The ratio between total cross section k · Ak of all k recesses to the total area A of the displacement surface a - k · / VA reaches the theoretical value a = 1 for a massless displacement piston. If circular recess surfaces Ai are assumed, then the relationship between the number k of circular recesses with the diameter d _k to the total area A with the diameter d as the area ratio a with

a = k · (d _k ² / d ² ).

This relationship applies with increasing number k of the recesses and thus smaller area K of the individual recesses

also for all non-circular shapes of the recess surfaces.

The size d _k then corresponds to the hydraulically equivalent diameter of the respective shape of the recess. At net-like Structures of the displacement surface are values 0.95 <a <1.0 reachable, so that the reduction in mass over 95% over a

massive displacement surface amounts.

Due to the inventive design of the positive displacement in the volume flow sensor is the apparent

contradictory effect that with increasing recess surface and thus lighter displacement piston the

Requirements for the tightness of the displacement surface are getting smaller. Just this effect causes a and

the same displacement piston can be used both after the displacer · and after the throttle principle.

The fluid enters through one of the connections for the fluid flow into the guide cylinder and displaces despite recesses

in the displacer the practically massless displacement piston synchronous to the delay

Flow rate change. This is due to the lack of piston mass by the measurement of the alternating volume flow

itself causes no pressure feedback. The piston movement is detected in a known manner via non-contact measuring systems, which are arranged at suitable locations of the guide cylinder. Since a druckrückwirkungsfrele measurement of

Volumetric flow is possible, allows the fast flow meter with simultaneous measurement of alternating pressures

the direct determination of the dynamic impedance.

The recessed Verdrängerfläche according to the invention has the additional advantage that they are in locking the displacer

be used as a throttle and that it can be moved against the current direction during switching operations.

The rapid volume flow meter according to the invention is characterized by a simple construction and allows in

a large volume flow, pressure and toughness range the measurement of alternating flow rates and dynamic

Impedances of liquid, vapor and gaseous fluids both according to the positive displacement and the throttle principle. embodiment

The invention will be explained in more detail below andre) embodiments. For the sake of clarity, various embodiments of the fast volumetric flow meter according to the invention are shown in FIGS.

example 1 The rapid volume flow sensor according to the invention consists, according to FIGS. 1 and 2, of the recessed displacement surface 1,

which is frictionally connected with guide plates 2 and with a poled in the axial direction permanent magnet 3.

The displacement surface 1 and the guide plates 2 are made of thin-walled aluminum or lightweight pressure-resistant Plastic, so that the mass of the inventive aluminum or lightweight pressure-resistant plastic, so that the mass

the present invention acting as a displacer recessed displacer 1 due to the lack of material in the

Recesses 4 is extremely minimized. It can be practically achieved for each fluid that the recessed displacement surface 1 in the fluid to be measured by a

floating storage can be positioned almost smoothly.

In Figure 1 and Figure 2, the recessed Verdrängerfläche 1 with its guide blades 2 and the permanent magnet 3 in

a guide cylinder 5 playfully floating guided.

The guide cylinder 61st on both sides, each with a flange β and 7 closed via a respective Qummidichtung 8, wherein the Flanges 6 and 7 are pressed by clamping screws 9 to the end faces of the guide cylinder 5. The flanges 6 and 7

have threaded openings 10 and 11, which are provided for screwing in the inflow and outflow line.

On the periphery of the guide cylinder 5 made of low permeability material is an induction coil 12

arranged, which is connected via the terminals 13 and 14 electrically connected to a changeover switch 15. On the circumference of the

Guide cylinder 5 are each a Hall sensor 16 and 17 arranged positively and via the electrical lines 18 and 19

connected to an operational amplifier 20 and the switch 15.

One in the flange 6 positively arranged weekly pressure sensor 28 is connected to a measuring line for alternating pressures 29. Inside the flange 7 pressure sensors 21 are arranged, via the electrical connection 22 and a Operational amplifier 23 are led to the changeover switch 15. At the switch 15 are in addition to the operational amplifiers 20 and 23 and the terminals 13 u ** M still dio measuring line 24th

for the measurement of the alternating volumetric flow, the excitation current exciter line 26, the counting line 26 for the aftermath

Displacement principle and the measuring line 27 for the quasi-stationary volume flow measured according to the throttle principle

connected.

During the measuring process, the fluid flows into the hollow space of the guide cylinder 5 as shown in FIG. 11n and displaces it

while the virtually weightless, recessed displacement surface 1 with the guide plates 2 inertia-free.

The non-positively coupled permanent magnet 3 follows each stationary and unsteady movement of the

recessed displacement surface 1 and induces one of the airspeed and thus a volume flow proportional

Voltage between the terminals 13 and 14, via the measuring line 24 as a measured value for the volume flow fluctuations

is registered.

Has the permanent magnet 3 moves to the hall sensor 17, via the electrical connection 19 and the Operational amplifier 20 switched in the switch 16 from the measuring line 24 to the excitation line 25. About the Exciter line 25 is now poled according to such a high external voltage between the terminals 13 and 14

abandoned that the permanent magnet 3 a linear motor equal to its initial position to the hall sensor 16 against the

Flow direction is withdrawn. The movement of the displacer against the flow direction is inventively through the recesses 4 in the Displacement surface 1 possible. The Hall sensor 16 causes via the terminal 18 and the operational amplifier 20, a switching back of the switch 15 of

the excitation line 25 to the measuring line 24. Measuring the volume flow fluctuation can thus start again until the

Permanent magnet 3 reaches the Hall sensor 17 and again switching from the measuring line 24 to the excitation line 25th

causes.

In the switch 15 is counted on the counting line 26 at the same time the number of Umsrhaltungen so that it also the

quasi-stationary volume flow can be calculated.

If the Hall sensors 16 and 17 are switched off, then the recessed displacer surface 1 strikes against the guide lamella 2 Flange 7 on and stops. It acts with their recesses 4 as a throttle. The throttle force is a measure of the Volume flow. It is transmitted via the guide plates 2 to the pressure sensors 21 and via the terminal 22, the Operational amplifier 23 and registered via the measuring line 27 as a measure of the quasi-stationary volume flow. The described rapid volume flow sensor is simple to produce in terms of manufacturing, because of the invention

recessed displacer 1, the guide blades 2 and the permanent magnet 3 existing displacement no

Fine dimensions requires and to the surface treatment of the guide cylinder 5 small demands are made. An expensive switching of the flow through directional control valves is unnecessary, since the recessed verdiängerfläche 1

can be returned against the flow direction. During the return period, the measuring process is hidden.

The effect of the measuring process via the measuring line 24 for the AC flow and the counting line 26 for the

quasistationären volume flow based despite the existing recesses 4 on the displacement principle, so that large

Pressure, toughness, and volumetric flow changes are allowed without significant errors. Since the mass of the displacer be reduced almost arbitrarily according to the design of the area ratio

can, volumetric flow fluctuations are far in excess of 1000Hz measurable. The measuring process itself causes virtually no

Pressure fluctuations, so that the recorded with the pressure sensor 28 via the measuring line for alternating pressures 29 Alternating pressures together with the recorded over the measuring line 24 change volume flows to the dynamic Impedance measurement can be used directly. The existing of the guide cylinder 5 and the flanges 6 and 7 measuring space

completely sealed, so that the fast flow rate sensor operates leak-free.

The recessed Verdrängerfläche 1 has the advantage that they in the idle state, so here at the ready, as a throttle for Measurement of the quasi-stationary volume flow is usable. Example 2 FIG. 3 shows a further embodiment of the fast volumetric flow meter according to the invention. This Volumetric flow meter is used to measure the quasi-stationary flow rate according to the throttle principle and the measurement

fast volume flow change according to the displacement principle. Also in this solution, the signals for the quasi-stationary volume flow of Hall sensors 16 and 17 and the signals for the volume flow changes through

Induction coils 12 detected in conjunction with permanent magnets 3. The inventive rapid volume flow sensor consists of the recessed displacement surface 1, with Guide plate 2 is provided, on which the permanent magnets 3 are arranged. The displacement surface 1 and the guide blades 2 are made of a thin-walled aluminum and / or from a

lightweight pressure-resistant plastic, so that the mass of the present invention act as displacer recessed

Displacement flat 1 due to the lack of material in the recesses 4 and minimized between the guide plates 2

becomes. The sum of the recesses 4 corresponds to the available Drosselflächi.

The positive displacement surface 1, guide plates 2 and permanent magnets 3 existing combined displacement / Throttle piston is floating on the guide plates 2 in the guide members 30 and 31 and thus ι practically ibungsfrei

mounted radially and axially. The guide roller 30 and 31 are inserted into the spiked intermediate pieces 32 and 33 positively and / or non-positively. The intermediate pieces 32 and 33 are clamped firmly by means of the clamping screws 9 via the rubber ring seals 8 between the flanges 6 and 7 and the lancing piece 42. About the guide members 30 and 31 induction coils 12 are pushed, which are electrically guided via the terminals 13 and 14 to the outside. In the intermediate pieces 32 and 33 radial bores 34 and 35 are provided, in which the Hall sensors 16 and 17 are arranged and which are guided via the terminals 18 uno 19 to the outside. In the wall of the spacer 42 is a change-pressure sensor 28 is positively arranged, which is connected to the measuring line for alternating pressures 29. In each case zwlrchen the permanent magnets 3 and 43 can each be a weak Zentrlerfeder 36 clamped. The volumetric flow meter shown in Figure 3 is symmetrical, so that it is equally suitable for the measurement of fluid flows in left · and in the right direction.

The function is also secured if only one induction coil 12 and only one Hall sensor 16 and 17 are used. For example, assuming a flow direction from left to right, the recesses 4 of the displacement surface 1 are flowed through from left to right. The resulting frictional force in the recesses 4 causes a displacement of the displacement surface 1 and thus on the guide plates 2 and the permanent magnet 3 to the right. The shift takes place until the magnetic force between the permanent magnets 3 plus the spring force of the centering spring 36 is in equilibrium with the frictional force generated in the recesses 4. The path traveled by the permanent magnets 3 in this case corresponds to the quasi-stationary volume flow and is received by the Hall sensors 16 and 17 and the signal is relayed via the stops 18 and 19 for processing. In order to measure the quasi-stationary volume flow, the frictional force generated in the recesses 4 of the displacer surface 1 by throttling action is utilized according to the invention.

The fast alternating volume flows to be measured cause an alternating movement of the displacer surface 1 around its equilibrium position caused by the quasi-stationary volumetric flow. The positive displacement according to the invention, despite recesses 4 and therefore practically massless displacement surface 1 guarantees a delay-free tracing of the fast AC flows through arranged on the guide plates 2 and thus changing permanent magnet 3. These induce in the induction coils 12, the alternating movements following AC voltage via the terminals 13 and 14 can be tapped as a measure of the alternating volume flows. Together with the alternating pressure signals In the measuring line for alternating pressures 29 the dynamic impedance can be determined. Due to the hollow permanent magnets 3 and 48 and guide parts 30 and 31, the throttling effect and the displacement effect also correspond to the same conditions in the flow center as on the entire remaining displacer surface 1.

Example 3 FIGS. 4 and 5 show a further embodiment of a quick volumetric flow meter according to the invention.

which differs from Examples 1 and 2 in that, in contrast to the axial movement of a

Rotary movement of the displacer surface 1 for measuring as well as quasi-stationary as well as faster volume flows after Verdrängerprinzp is used. Derquaslstatlonäro volume flow is determined by that a counting operation on the Hall sensors 16 and 17 is triggered. The alternating volume flow is detected by the induced voltage in the induction coils 12. The inventively ausgestatete volume flow sensor consists of a slotted displacement surface 1, which at a Slotted socket 37 is attached. Displacer 1, Schlitzbi: hse 37 and permanent magnet 3 are mutually force and / or

positively connected. The existing of the displacement surface 1, the slot bushing 37 and the permanent magnet 3 extremely low-mass displacement piston is floating on the bushing 38 on dar 38 bushing, almost reliingsfrel radially.

The measuring space of the fast flow meter is through the side walls 39 and 40 and the housing 41 and the Bush 38 formed. The rubber ring seals 8 provided with the end face of the housing 41 and the socket 38 are with

the side walls 39 and 40 tightly closed over the clamping screws 9 to the outside.

The side walls 39 and 40 are provided with central openings 44 and 45 through which the induction coil 12 inside the Socket 38 can be positioned. The induction coil 12 is connected via the terminals 13 and 14 with the switch 15th

connected.

At the socket 38, the Hall sensors 16 and 17 are positively arranged, the electrical connection via the Connections 18 and 19 with the operational amplifier 20 and the connection 22 with the switch 15 in conjunction

stands. The measuring space is divided by a slotted blocking surface 46, wherein the blocking surface 46 comb-like negative of the

Slot shape of the recesses 4 of the displacement surface 1 is formed and fixedly connected to the housing 41. On the side wall 40, an alternating pressure sensor 28 is arranged inside, which communicates with the measuring line for Wecliseldrücke 29th

connected is.

The rapid volume flow sensor shown in Figure 4 and 5 is symmetrical, so that he, as already in Example 2, is simultaneously suitable for both directions of the fluid flow. For the flow direction shown in Figure 4, the fluid flow causes a practical invention

Delay-free and pressure-drop-free clockwise rotation of the displacer surface 1 despite comb-like recesses 4.

Starting from the drawn in Figure 1 position of the displacement surface 1, which is registered by the Hall sensor 16, to the

rotated by 180 ° Clockwise, which is registered by the Hall sensor 17, succeeds by the invention

Blocking effect of both provided with recesses 4 displacement surface 1 and the similarly designed blocking surface 46th

Despite a rotating movement an error-free displacement, due to the lack of pressure drop between inlet and outlet, the blocking surface 46 acts in spite of the recesses as a blocking surface and thus prevents a short-circuit flow between the

Fluidein- and the fluid outlet. The accuracy is no longer given in the further rotation of the displacer 1 from the Hall sensor 17 to the Hall sensor 16. To hide and shorten this period of inaccuracy, causes the Hall sensor 17 via the switch 15, that

via the excitation line 25, a correspondingly poled DC current flows into the indication coil 12 and the resulting electric field acts in conjunction with the acting as an armature permanent magnet 3 as an electric motor and on the

Schlitzbuchso 37 the displacement surface 1 to the Hall sensor 16 rotates, where this on the changeover switch 15 back to the Switches measuring line. In the measuring range, the displacer surface 1 follows at changing volumetric flow rates Fluldes, so that the alternating permanent magnet 3 In the induction coil 12 also a varying voltage

Induced.

Since the measuring space between the switching points through the Hall sensors 16 and 17 on the upper 18O 'rotation angle

is geometrically known, is the number of switching a measure of the measured quasi-stationary volume flow.

Both the determination of the alternating volumetric flows and of the quasi-stationary volumetric flow takes place without pressure drop,

Zählgkelts- and density-independent, so that with simultaneous measurement of pressure and alternating pressure direct measurement of quasi-stationary and dynamic impedance is possible.

Claims (5)

1. Fast volumetric flow meter, consisting of a measuring chamber, which is provided with a Fluidein- and fluid outlet, arranged in the measuring chamber a displacer and a locking device and are arranged in the guide or on the leadership of the displacer non-contact measuring systems, characterized in that the displacer consists of a displacement surface (1) provided with recesses (4) and, in the case of a rotating movement of the displacement piston, there is additionally a blocking surface (46) likewise provided with recesses (4) and secured to the housing (41), the area ratio a = k * ( d _k ² / d ² ) approaches the value 1 if the number k of the recesses (4) is very large and each of its k hydraulically equivalent diameter d _{k is} smaller than the total hydraulically equivalent diameter d of the displacer surface (1) and / or the Locking surface (46) is. 2. Fast volumetric flow meter according to claim 1, characterized in that the recesses (4) of the VerVerser-surface (1) and the locking surface (46) are round, reticulate or comb-like. 3. Fast volume flow sensor according to claim 1 and 2, characterized in that on the displacement surface (1), the guides are arranged as guide plates (2). 4. Fast volume flow sensor according to claim 3, characterized in that the guide plates (2) rod-shaped and rotationally symmetrical in the guide part (31) or to the bushing (38) are arranged. 5. Fast volume flow sensor according to claim 3, characterized in that the guide plates (2) have the shape of a slot bushing (37) on which the displacement surface (1) is arranged on one side. For this 4 pages drawings