DE102004010408A1 - Ultrasonic flowmeter has an ultrasonic transducer and ultrasound mirror that has an additional flow guide for optimizing the fluid flow over its surface - Google Patents

Abstract

Ultrasonic flowmeter for measuring the flow rate of a flowing liquid or gas has a housing (1) that encloses a measuring section along which a differential time of flight measurement can be made using at least an ultrasonic transducer (2) and a ultrasound mirror (5) for guiding the sound beam. Fluid flow guiding elements are provided in the area of the mirror surface to optimize the fluid flow over the mirror surface. Independent claims are also included for the following:- (a) an ultrasound meter with an ultrasound deflection mirror holder (8) manufactured from two halves separated in a direction parallel to the longitudinal axis of the meter and; (b) an ultrasound meter with an ultrasound deflection mirror holder, mirror and measurement pipe that can be removed and inserted as a unit in the meter.

Description

The The present invention relates to an ultrasonic counter for Determining the flow rate of a flowing medium, in particular liquid or gas, with a housing, one inside the case arranged measuring path along which a transit time measurement, in particular Differential transit time measurement, feasible is at least one ultrasonic transducer, at least one deflection mirror, the upstream of the flowing Medium is, by means of which the ultrasonic wave of the ultrasonic transducer is deflected towards the measuring tube. With differential time measurement takes place the opposite Measurement either over Reflection of the ultrasonic signal of the ultrasonic transducer or via a from a further ultrasonic transducer sent ultrasonic signal at the opposite End of the measuring section.

The DE 201 07 894 U1 discloses an ultrasonic flowmeter of the generic type. In this case, the upper edge of the deflecting mirror facing away from the medium flows around, whereby a recirculation zone or zones of reduced flow velocity in the region of the surface of the first deflecting mirror form, causing contamination on the deflecting mirror. This suffers the long-term stability of the ultrasonic flowmeter.

The DE 199 30 278 A1 describes an ultrasonic counter with a first deflection mirror, which includes aligned parallel to the flow path holes that are intended to counteract contamination of the deflection mirror. However, the deflecting mirrors described therein are very expensive in their production, since a large number of holes, which are not perpendicular to the mirror plane, must be introduced.

The Object of the present invention is a novel ultrasonic meters to disposal on the one hand by long-term stability and insensitivity to contamination on the other hand, however, simple and inexpensive to manufacture is.

The The above object is the generic ultrasonic meter thereby solved that Means are provided in the region of the deflecting mirror, the flow in the Range of Umlenkspiegeloberfläche specifically affect, in particular a recirculation zone, a Zone with reduced flow and / or a zone of stagnant medium dissolved, displaced or reduced becomes. The basic insight of the invention is, means which affect the formation of such zones in the region of the deflecting mirror surface, namely prevent, postpone or at least significantly reduce them.

This may suitably in selected Flow areas occur which operated the meter typically becomes. Thus, can be guaranteed be that layers during a standstill phase or atypical flows again be removed.

Conveniently, the means comprise flow directors for the Generation of at least one directed partial flow, wherein the partial flow - in particular in the upper region of the first deflecting mirror - substantially parallel to the surface directed the first deflecting mirror. This partial flow prevents the formation of unwanted Flow zones, z. B. a recirculation zone in the region of the mirror surface and thus a gradual Deposition of dirt.

The Means are according to another embodiment of the present invention expediently especially provided in the region of the upper end of the deflecting mirror. They therefore have an immediate effect on themselves in this area as well resulting flow zones (eg recirculation vortex).

The Means can expediently in Area of Umlenkspiegelhalters and / or in the region of the deflection mirror yourself.

One suitable means is the mirror holder in the form of a laterally adjacent mirror holder extension to design, where The latter essentially flush on the surface of the first deflecting mirror is applied. This will, so to speak, the surface of the deflection mirror by means of the mirror holder extension and extended to the top. This ensures that the recirculation zone from the surface of Deflection mirror moves in the area of the mirror holder extension.

When Means are expediently at least one correspondingly directed nozzle or a corresponding Arrangement of several nozzles intended.

alternative or additionally can do this the means also at least one appropriately directed guide, in particular guide vanes, include.

in this connection can the nozzle either in the first deflection mirror, in Umlenkspiegelhalter or between first deflecting mirror and Umlenkspiegelhalter are.

According to a further embodiment of the present invention, the directional nozzle or nozzle is arched or curved. Also, the top end of the mirror holder extension is present formed partially curved.

Of Further, a return channel is formed in an advantageous manner, in due to a at the end of the return channel located mainstream according to the Venturi principle formed negative pressure takes place a backflow, which increased to an flow and thus leads to a self-cleaning of the mirror. Of the Return channel is in this case designed such that he in the area of the transition from Mirror to mirror holder extension runs substantially parallel to the mirror surface. Of the Return channel can pass through a protrusion on the mirror holder extension extend or through a correspondingly shaped mirror holder extension in conjunction with an additional Part be formed.

A further expedient embodiment of present invention is that the mirror extension holder in the area of his transition to Deflecting mirror a flat, substantially flush ending extension the Umlenkspiegeloberfläche forms, with the result that the recirculation zone in the area of the mirror holder extension moves.

One - also sibling claimed - embodiment The present invention is characterized in that Umlenkspiegelhalter expediently from two along a longitudinal Dividing line composed halves. This facilitates the use of the mirror as well as the other the preparation of Umlenkspiegelhalters as elaborately shaped plastic molding. Also can identical halves for additional Deflection mirror provided in the ultrasonic counter be. This idea allows optimal fixation of the deflection mirror, which is an important requirement to guarantee a long-term stability of the ultrasonic counter is.

If the deflecting mirror holder has means for fixing the measuring tube, is advantageously no housing processing necessary.

Further can the thermal expansion coefficients of mirror holder, housing and / or Mirror be adjusted.

Of the Deflection mirror has expediently parallel holding surfaces on. He can z. B. polygonal, in particular octagonal be, whereby better fixing accuracy can be achieved during installation. The fixation of the mirror takes place here z. B. form-fitting either via the four rectangular surfaces or over the four diagonal surfaces.

Farther can by corresponding pockets in the holder, the mirrors are held positively, what the long-term stability elevated.

Conveniently, shows the partial flow in Comparison to the mainstream a greater flow rate on.

The relationship of partial flow to total flow is ≤ 1:20 or is expediently in a range of 1:20 to 1: 130. This is not essential adulteration the mainstream and thus no negative impact the measuring characteristics of the ultrasonic meter.

The Retaining webs on Umlenkspiegelhalter can screen-shaped or as a flow straightener be educated.

Of the The subject matter of claim 18 has the advantage that - due the special fixation - one reduced tolerance of the components is possible.

One - also Also claimed in juxtaposed - embodiment of the present Invention is characterized in that deflection mirror holder, Deflection mirror and measuring tube as a unit from the housing of the ultrasound counter heraus- or in this hineinschiebbar and in particular without disassembly of the respective ultrasonic transducer. The maintenance and the service is thereby particularly simplified.

Conveniently, is or are the ultrasonic transducer (s) in the housing of the ultrasonic meter, for example flush with the inner surface of the measuring tube extending or further inward into the housing of the ultrasound counter put into it.

Of the Umlenkspiegelhalter is of at least one, preferably two Surround sealing rings, on the one hand, a sealing effect of Umlenkspiegelhalters to the housing of the ultrasonic counter on the other hand, the unit consisting of Umlenkspiegelhalter, Hold the deflection mirror and the measuring tube together so that they are inserted or pulling out is particularly easy to handle.

Advantageous embodiments The present invention will be described below with reference to drawings explained in more detail.

It demonstrate:

1 a sectional view of an ultrasonic counter of the type described above;

2 shows in a highly simplified schematic representation of the formation of a recirculation zone in a deflection mirror of the prior art;

3 shows a deflection mirror and Um steering mirror holder according to the present invention;

4 shows a further embodiment of a deflecting mirror and Umlenkspiegelhalters according to the invention in a longitudinal sectional view ( 4A ), in a frontal plan view of the deflection mirror ( 4B ) and one half of the Umlenkspiegelhalters in perspective representation ( 4C );

5 shows a highly simplified, schematic representation of a deflection mirror and Umlenkspiegelhalter with a return channel, which is integrated in the Umlenkspiegelhalter ( 5A ) and a return channel formed by the mirror holder extension and an additional part ( 5B );

6 a further embodiment of the deflection mirror and Umlenkspiegelhalters according to the invention with an extended mirror holder extension;

7 a further embodiment of the ultrasonic meter according to the invention in longitudinal section and perspective view with measuring insert;

8th the measuring insert of the ultrasonic counter according to 7 in the removed state as well

9 the area of the Umlenkspiegelhalters the ultrasonic counter after 7 in upstream plan view.

The representation in 1 shows a generic ultrasonic meter with a housing 1 , an ultrasonic transducer 2 and another ultrasonic transducer 3 , which in each case via housing openings provided for this purpose in the side wall of the housing 1 inserted and by associated covers with seals in the wall of the housing 1 are held.

The ultrasonic transducer 2 is a deflection mirror 5 , the other ultrasonic transducer 3 another deflection mirror 6 assigned. The measuring section 4 (ie the path of the sound signals) passes from the ultrasonic transducer 2 to the deflection mirror 5 , from the latter to the further deflection mirror 6 and from this to another converter 3 and back in opposite directions. The measuring section 4 therefore has a U-shape. However, other mirrors (not shown) and a diagonally extending sound guide may also be present within the scope of the invention (not shown).

The area between both deflecting mirrors 5 respectively. 6 the measuring section 4 is from a measuring tube 7 surrounded by a measuring tube holder 9 in the case 1 is held.

The medium, for. As service water flows through an inlet, not shown, in the representation of 1 from the left, flows around the deflection mirror 5 , flows along the measuring section 4 , flows around the further deflection mirror 6 and leaves the ultrasonic counter in the area of the (also not shown) outlet. The deflection mirror 5 respectively. 6 each of a Umlenkspiegelhalter 8th fixed, from the only deflection mirror holder 8th in the area of the deflection mirror 5 in 1 is shown.

In the prior art, the problem arises that when flowing around the deflecting mirror 5 especially in the area of the top z. B. a so-called recirculation zone 16 forms, which can lead to deposits on the surface of the deflection mirror and thus to a deterioration of the long-term operation with increasing time. These deposits are in 2 (exaggerated) with the reference number 19 shown. The recirculation zone is the area in which the recirculation vortex 20 along the surface of the deflecting mirror 5 form.

An embodiment of the ultrasonic counter according to the present invention is shown in FIG 3 explained in more detail. Consequently, it is located in the region of the Umlenkspiegelhalters 8th a nozzle 12 for generating a partial flow, which in the upper region of the surface of the first deflection mirror 5 is directed parallel to the surface. This partial flow prevents the formation of recirculation vortices 20 and thus a recirculation zone. The nozzle has a slightly curved course and extends towards the mirror surface with a continuously tapering cross section. The nozzle 12 is expediently flat, so that the partial flow has a wider surface area of the deflecting mirror 5 detected.

The holder 8th is sleeve-shaped and is axially in the housing 1 of the ultrasonic counter inserted. In addition, the holder points 8th expediently - as in 3 shown - circumferentially arranged, large-scale openings on. In which the holder of the deflecting mirror 5 opposite region of Umlenkspiegelhalters 8th There is a circumferential recess that serves as a receptacle 10 for a in 3 not shown measuring tube holder (reference numeral 9 in 4A ) serves.

The deflection mirror 5 becomes in an arrangement of a plurality of opposite retaining projections 13 fixed to two parallel surfaces, of which in 3 only two are shown for clarity.

Due to the design and arrangement of the nozzle 12 becomes a small compared to the volume of the main flow partial flow parallel to the surface of the first deflection mirror 5 On whose introduced top end at high speed and thus requires avoidance or at least significant reduction in the formation of Rezirkulationswirbeln 20 in the area of the surface of the deflecting mirror 5 , The fact that the partial flow only a fraction (the cross-sectional ratios are 2-4 mm ² at 50 - 400 mm ² for main flow) includes the total flow, for example, 1: 100 of the total flow caused by the partial flow no significant distortion of the main flow and thus none negative impairment of the measuring characteristics of the ultrasonic meter.

Of the Umlenkspiegelhalter is suitably made of a material with high modulus of elasticity, in particular made of plastic, for. B. made of fiber-reinforced plastics such as PES, PSU, PPSU, PPA, PEI, PEEK / PEAK including theirs Derivatives PPS or PPE. In particular, by mixing glass or carbon fibers thermal expansion the housing (typically metal) can be adjusted.

The holding webs of Umlenkspiegelhalters 8th are kept small in cross-section, for example less than 4 mm ² (eg 2 × 2 mm) in order to keep the pressure loss in the mirror flow around low and to be able to neglect the webs acoustically. The cross-sectional geometry of the webs of Umlenkspiegelhalters 8th has expediently a turbulence of the medium favoring form, as will be explained later.

Alternatively, the webs 22 of Umlenkspiegelhalters 8th - see. 7 - But also have a rectifying effect on the flow, in particular on the inlet flow.

Even larger foreign bodies, which could damage the ultrasonic counter, are through the webs 22 of Umlenkspiegelhalters 8th or their arrangement intercepted. The bridges 22 may alternatively be formed in a sieve-shaped.

4A shows a further embodiment of the invention. The Umlenkspiegelhalter shown there 8th corresponds to the deflection mirror holder 8th the embodiment according to 3 , Instead of the nozzle is in the embodiment according to 4A an arrangement of guide vanes 14 intended. These baffles 14 also ensure the formation of a corresponding partial flow, which at the upper end of the deflection mirror 5 directed in parallel to its surface.

To ensure easy manufacturability, in particular as a plastic molded part, the Umlenkspiegelhalter 8th the embodiment according to 3 such as 4 formed in the form of two longitudinally cut halves, as is apparent from 4B results. The two halves are mirror-symmetrical to each other. The guide wings 14 each half of the Umlenkspiegelhalters 8th may be arranged as an additional part provided or integrated into the molding.

Out 4A In addition, the attachment of the measuring tube 7 via its measuring tube holder 9 as well as the recording 10 for the measuring tube holder 9 recognizable. In 4B are identical features of the two halves of Umlenkspiegelhalters 8th drawn only once.

Except for the difference, all apply to the design 3 mentioned features equally for the design according to 4 ,

Like from the 4B such as 4C continues to show, is the deflection mirror 5 octagonal formed and is about corresponding retaining projections 13 held on diametrically opposed parallel edges held. As a result, a particularly secure fixation of the deflection mirror 5 guaranteed.

The first deflecting mirror 5 is suitably made of a sheet metal part, which is either stamped or water jet cut.

The above statements on the first deflection mirror 5 apply equally to the design of the ultrasonic counter after 3 as well as for the embodiments described below.

In the embodiment according to 5A , which only the deflection mirror 5 and the related Umlenkspiegelhalter 8th shows, via a Venturi effect, a partial negative pressure to generate a directed backflow 15 along a portion of the surface of the deflecting mirror 5 generated. This is at the top of the mirror holder extension 18 a curved guide surface together with a return channel 17 intended. The return channel 17 runs out of the plane of the surface of the deflecting mirror 5 slightly curved in the direction of the flow. The resulting backflow 15 ensures a permanent suction of deposits in the area of the mirror surface and thus a self-cleaning effect.

The same applies to the design after 5B , The only difference here is that the return channel 17 through the mirror holder extension 18 on the one hand and an additionally provided nose 21 is formed.

In the embodiment according to 6 is also a mirror holder extension 18 provided, wel cher on its upper side has a curved guide surface. Here is the mirror holder extension 18 elongated so that an elongated, substantially planar surface is flush with the upper end of the surface of the deflecting mirror 5 followed. This will cause a shift of the recirculation zone 16 in the area of the mirror holder extension 18 causes. At the same time, a substantially parallel to the surface of the first deflection mirror takes place 5 Directed flow, which prevents deposits in this area.

7 shows a further embodiment of the ultrasonic counter according to the invention in longitudinal section. The streamline-shaped deflecting mirror holder is particularly easy to recognize 8th including the retaining bars 11 , The deflecting mirror holder 8th is a single molded part and includes the inclusion of the deflection mirror 5 , the retaining bars 11 as well as the recording 10 for the measuring tube holder 9 of the measuring tube 7 ,

In the embodiment according to 7 is the deflection mirror holder 8th over the total length of the measuring section 4 formed in one piece, that carries both the one deflecting mirror 5 as well as the further deflection mirror 6 , In addition, the deflection mirror holder 8th via a centrally mounted fixing element 22 held in position, whereby the components (due to the symmetrical fixation) can be manufactured with a reduced tolerance.

At the same time takes the one-piece Umlenkspiegelhalter 8th the measuring tube 7 on. For this purpose, the Umlenkspiegelhalter 8th - across the measuring section 4 considered - divided into two, so that between the two shells of Umlenkspiegelhalters 8th the respective deflection mirror 5 respectively. 6 as well as the measuring tube 7 used and the measuring insert formed thereby 25 , see. 8th , by circumferential sealing rings 23 . 24 is held together. In this form, the measuring insert 25 in a simple way in the housing 1 be inserted or removed from the ultrasonic counter. The sealing rings 23 . 24 Moreover, they serve to seal the area of the measuring insert 25 to which the fixing element 22 attacks. The deflecting mirror holder 8th owns according to 8th a recess 26 into which the fixing element 22 in the locked state of the measuring insert 25 intervenes. numeral 27 denotes the dividing line of the Umlenkspiegelhalters 8th longitudinal. The deflecting mirror holder 8th includes in the area of the measuring tube 7 a plurality of openings 28 ,

The ultrasonic transducers 2 . 3 are in the case 1 of the ultrasonic counter, arranged parallel to the flow direction. As a result, the measuring insert 25 out of the case 1 be pushed out or inserted into the same, without the ultrasonic transducer 2 . 3 must be dismantled.

9 shows a plan view of the Umlenkspiegelhalter 8th from the upstream side. The deflecting mirror holder 8th includes two crossed holding webs 11 , with which a flow rectification is achieved. In the middle area of the Umlenkspiegelhalters 8th is the deflection mirror 5 positioned.

Various Features of the above-described embodiments of the ultrasonic counter according to the invention can in be exchanged with each other in any way.

With The present invention is a novel ultrasonic counter for disposal whose deflection mirror is free of deposits and thus has improved long-term stability. At the same time the ultrasonic counter in easier and cheaper Way to produce. The invention therefore represents a very essential Post on the relevant Field of technology.

1

casing

2

ultrasound transducer

3

ultrasound transducer

4

measuring distance

5

deflecting

6

deflecting

7

measuring tube

8th

Umlenkspiegelhalter

9

Measuring tube holder

10

admission for measuring tube holder

11

holding web

12

jet

13

retaining projection

14

vanes

15

backwash

16

recirculation zone

17

Return channel

18

Mirror holder extension

19

deposits

20

recirculation vortex

21

nose

22

fixing

23

seal

24

seal

25

Feeler

26

recess

27

parting line

28

opening

Claims (21)

Ultrasonic counter for determining the flow rate of a flowing medium, in particular a liquid or a gas with a housing ( 1 ), one within the housing ( 1 ) arranged measuring section ( 4 ), along which a transit time measurement, in particular Differenzlaufzeitmes is feasible, at least one ultrasonic transducer ( 2 ), at least one deflecting mirror ( 5 ), by means of which the ultrasonic wave of the ultrasonic transducer ( 2 ) is deflected, characterized in that means in the region of the deflection mirror ( 5 ) are provided, which influence the flow in the region of the Umlenkspiegeloberfläche targeted. Ultrasonic meter according to claim 1, characterized in that the means comprise flow guiding devices for at least one directed partial flow and, in particular in the upper region of the deflecting mirror (US Pat. 5 ), the partial flow substantially parallel to the surface of the first deflection mirror ( 5 ). Ultrasonic counter according to claim 1 or 2, characterized in that the means in the region of the upper end of the deflection mirror ( 5 ) are provided. Ultrasonic counter according to one of the preceding claims, characterized in that the means on the Umlenkspiegelhalter ( 8th ) and / or at the deflection mirror ( 5 ) are located. Ultrasonic counter according to one of the preceding claims, characterized in that the means comprise a mirror holder extension ( 18 ) substantially flush with the surface of the deflection mirror ( 5 ) is present. Ultrasound counter according to one of the preceding claims, characterized in that the means comprise at least one nozzle ( 12 ). Ultrasound meter according to one of the preceding claims, characterized in that the means comprise at least one guide device, in particular at least one guide blade ( 14 ). Ultrasonic meter according to claim 6 or 7, characterized in that the nozzle ( 12 ) in the deflection mirror ( 5 ), in Umlenkspiegelhalter ( 8th ) or between deflecting mirrors ( 5 ) and deflecting mirror holder ( 8th ) is located. Ultrasonic counter according to claim 6 - 8, characterized in that the nozzle ( 12 ) or guide is curved. Ultrasonic meter according to claim 9, characterized in that a return channel ( 17 ), in particular in the region of the upper-side end of the deflecting mirror ( 5 ), is provided. Ultrasonic meter according to claim 10, characterized in that the return channel ( 17 ) by a projection of the mirror holder extension ( 18 ) extends therethrough. Ultrasonic counter according to one of claims 5 - 11, characterized in that the mirror holder extension ( 18 ) forms a substantially flush with the Umlenkspiegeloberfläche, flat transverse surface extension thereof. Ultrasonic counter for determining the flow rate of a flowing medium, in particular a liquid or a gas with a housing, a arranged within the housing measuring path, along which a transit time measurement, in particular differential transit time measurement is feasible, at least one ultrasonic transducer, at least one deflection mirror, by means of which the ultrasonic wave of the Ultrasonic transducer is deflected, in particular according to one of the preceding claims, characterized in that the Umlenkspiegelhalter ( 8th ) is constructed of two halves separated in the longitudinal direction. Ultrasonic meter according to one of the preceding claims, characterized in that the deflecting mirror holder ( 8th ) Means for fixing the measuring tube ( 7 ) having. Ultrasonic counter according to one of the preceding claims, characterized in that the deflecting mirror ( 5 ) has mutually parallel mounting surfaces. ultrasonic meters according to one of the preceding claims, characterized that the partial flow in comparison to the mainstream one greater flow rate having. ultrasonic meters according to one of the preceding claims, characterized that the ratio of partial flow to total flow ≤ 1:20, preferably in a range of 1:20 to 1: 130. Ultrasonic meter according to one of the preceding claims, characterized in that the deflecting mirror holder ( 8th ) both the one deflecting mirror ( 5 ) as well as the further deflecting mirror ( 6 ) and the deflection mirror via a particular centrally arranged fixing element ( 22 ) is held in position. Ultrasonic counter for determining the flow rate of a flowing medium, in particular a liquid or a gas with a housing, a arranged within the housing measuring path, along which a transit time measurement, in particular differential transit time measurement is feasible, at least one ultrasonic transducer, at least one deflection mirror, by means of which the ultrasonic wave of the Ultrasonic transducer is deflected, in particular according to one of the preceding claims, characterized in that Umlenkspie gel holder ( 8th ), Deflection mirror ( 5 respectively. 6 ) and measuring tube ( 7 ) as a unit from the housing ( 1 ) of the ultrasonic counter out or in this hineinschiebbar. Ultrasonic counter according to one of the preceding claims, characterized in that the ultrasonic transducer ( 2 ) or the ultrasonic transducers in the housing ( 1 ) of the ultrasonic counter is or are located. Ultrasonic meter according to one of the preceding claims, characterized in that the deflecting mirror holder ( 8th ) of at least one, preferably two sealing rings ( 23 . 24 ) is surrounded.