FI71022C - MAETANORDNING FOER MAETNING AV VOLYMSTROEMMEN AV EN MEDIUMSTROEM - Google Patents

Description

r, ANNOUNCEMENT

B (11> UTLÄGGNINGSSKRIFT 710 2 2 ‘.....

(51) Kv.lk. * / Lnt.CI. 'G 01 P 5/1 * 1 FINLAND — FINLAND (21) Patent application Patentansöknlng 79200 * 4 (22) Application date Ansöknlngsdag 25.06.79 (23) Starting date - Giltighetsdag 25 06 79 (41) Made public — Blivit offentlig 2 ^] 2 80

National Board of Patents and Registration Date of publication and publication. -

Patent and registration authorities '' Ansökan utlagd och utl.sk rif ten publicerad 18.07.86 (86) Kv. application Int. ansökan (32) (33) (31) Privilege requested - Begärd priority (71) Lapinleimu Oy, 37800 Toijala. Suomi-Fin I and (FI) (72) Pauli Grönberg, Espoo, Suoni iF in 1 and (F!) (7 * 0 Seppo La ine Ky (5 * 0 Measuring device for measuring the volume flow of a medium -Mätanordning för mätninq av vo! Ymströmmen av en mediumström

The invention relates to a measuring device according to the preamble of claim 1 for measuring the pressure difference and the volume flow of a medium flow in a flow channel.

Prior art volumetric flow measurement methods and devices require a near-disturbance flow profile at the measurement point in order for the measurement error to be small enough. In general, in practical installation cases, the flow profile is not sufficiently undisturbed without special flow straightening and smoothing devices, because the flow channels do not have sufficiently long straight channel sections where the flow profile would have time to level off. Thus, the measurement accuracy has remained poor. In some cases, a reliable measurement result has not been reasonably achievable.

In the past, no measuring and control devices have been available with which the volume flows of ventilation systems can be measured and adjusted to the designed values with sufficient effort and precision, even under disturbed flow conditions.

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Today, more than half of the energy loss in buildings is due to ventilation. In the future, energy saving measures in buildings will require sufficiently precise management of energy flows. This is not possible unless the volume flows (= energy flows) of the ventilation systems can be measured more reliably and adjusted more easily.

FI publication 59 175 discloses a volume flow-flow measuring device for a medium flow, which is primarily suitable for measuring the air flows of a ventilation plant even better than at present, even when the flow profile is strongly disturbed. The measuring device is intended for fixed installation in a ventilation system. The measuring device can be used in various embodiments in circular, oval, rectangular and other shaped current channels and openings.

It is an object of the present invention to further develop the measuring devices disclosed in the above-mentioned publication.

With regard to the state of the art related to the invention, reference is further made to previous FI patent applications 780740 and 782384.

It is a particular object of the invention to provide a measuring device which, when detecting a pressure difference, provides an even more accurate and larger reading and thus a higher measurement accuracy of the volume flow. It is also intended to provide greater measurement accuracy, especially in highly disturbed, e.g. asymmetric, flow profiles.

These objects can be achieved with a measuring device according to the invention, which is mainly characterized in that at least one of the tubular members is at a certain distance from the annular plate, whereby each opening in this tubular element opens towards the annular plate.

The measuring device according to the invention comprises an annular plate with which the necessary measurable pressure difference is obtained. The outer diameter of this flange is substantially smaller than the inner diameter of the measuring channel. Attached to both sides of said plate are tubular members provided with small diameter openings, e.g. holes, through which pressure is detected on both sides of the flow resistor. Preferably, said annular plate and the tubular members attached thereto are arranged coaxially with the flow channel.

With the measuring device according to the invention, irm. the following practical advantages: - the device according to the invention easily achieves a measurement accuracy of better than 5 ... 10% even in difficult conditions, 3 71022 - flow disturbances do not significantly affect the operation of the measuring device and the achievable measurement accuracy, - the volume flow can be Hoi lifted with one jxiine difference 1 tnuksel 1a, - the measuring device can be used at both low and high flow rates, - the measured pressure difference is large, compared to mi 1! - the structure of the measuring device remains simple, - the pressure difference to be measured remains stable, - the measuring device provides sufficient measuring accuracy even in disturbed flow, - the measuring device is suitable for use in , - the measuring device is suitable for measuring the volume flows of both gases and liquids, - the flow directions.la has no effect on the operation of the measuring device, - the measuring device has no need for space outside the duct or opening, and - the measuring device is also suitable for as a measuring control device.

The invention will now be examined in more detail by means of exemplary embodiments according to the accompanying drawings.

Figure 1 shows a known measuring device according to FI publication 51175 in axial section.

Fig. 2 shows the measuring device according to Fig. 1 in a flow direction.

Fig. 3 shows a view of one embodiment of a pipe member arrangement of a measuring device according to the invention.

Figure 4 shows a sectional view of another embodiment of the tubular member arrangement of a measuring device according to the invention.

Figure 5 shows a sectional view of a third embodiment of a pipe member arrangement of a measuring device according to the invention.

Figures 6-10 show: as profile views alternative embodiments of a ring plate used in connection with a measuring device according to the invention.

The known measuring device according to Figures 1 and 2 consists of an annular plate 10, on both sides of which annular tubular members 12 are fastened, the interior of which is connected by pipes 14 outside the channel 16 to hoses 15 leading to a pressure gauge. The annular tubular members 12 preferably have small diameter holes 13 on both sides, which open substantially perpendicular to the flow direction F. Through the said holes, a pressure difference Aβ is obtained, which is provided by a flow resistance, in this case an annular plate 10.

The measurement method to be used is suitable in this connection (for more detailed FI patent applications in 780740 and 782384.

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The tangential diameters c of the annular putt devices 12 as well as the ring plate 10 are substantially smaller than vix in Danish van 1 f> hai ka is i. Ia ci. The latter dimension d is considerably larger than the outer position b of the annular plate 10. Thus, between the outer edge of the flow channel 16 and the outer edge of the annular plate 10 there is a rupture space B through which the flow can pass. The shoe plate 10 has an opening Λ with a diameter of a. Through this opening Λ passes a non <e, a vi it ausk.innva from the flow F. The dimensions a, b, e and d shown above are va 1 so that as large as possible measurement accuracy is achieved under different measurement conditions. An example of a suitable dimensioning is the dimension m shown in Fig. 1, in which case the quantity d / c «s is 1.3.

In the case according to Fig. 3, according to the invention, both surface-large tubular plates 12 are spaced apart from a straight ring plate 10 in profile. This distance is, for example, in the range 30 ... ISO k from the outer diameter of the tubular member 12. In the case according to Fig. 3, this distance e is about 50% of the ape 12 of the tube. The holes 13 in both tube members 12 open towards each other in the ring plate. This system is very good and the Pirkka weight difference is new! Idol li suns put k between the L-members 12.

In the case according to Fig. 4, in the flow direction F, the first tubular member 12 is spaced apart from the annular plate 10, while the second cantilever member 12 is either closed or almost fixed in the corrugated plate 10 in a known manner. In this case, the holes in both tubular members 12 11 open upstream in direction F.

In the case according to Fig. 5, the arrangement of both wooden selectors 12 and the arrangement of the holes of the first pipe member 13 with respect to the annular plate 10 is according to Fig. 4. Instead, 12 holes in the second tubular member. 1.1 open substantially in a direction i parallel to the flow direction F.

It should be noted that in addition to the arrangement of the east tube 12 and the holes 13 or slots therein, the measurement accuracy can also be affected by appropriately shaping the profile of the ring plate 10. Such preferred ring plate 10 profiles are isolated in Figures 6-10.

Fig. 6 shows a structure in which the outer edge of the ring 1cvy has an axial flange.

In the case of Fig. 7, in turn, an axial flange is arranged on the inner edge of the ring plate 10.

The solution according to Figure 8 has an axial flange at both the outer and inner edge of the plate.

The structure according to Figure 9 has two coaxial grooves curved to the profile.

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The annular plate 10 according to Figure 10 is finally completely curved in profile so that the profile corresponds to the arc of a circle, for example a semicircle.

Although only the small-diameter perforation 13 of the annular tongue member 12 has been discussed above, it will be appreciated that a corresponding narrow slit or several successive slits or perforations of different shapes may be used instead of the perforation.

It should also be noted that, within the scope of the invention, also in the flow direction F, the second pipe member 12 may be spaced apart from the plate plate 10, while the first pipe member 12 may in turn be closed or. almost attached to the ring plate 10.

The measuring device according to the invention can be applied to very different duct cross-sections, even those in which the duct walls are formed as combinations of planar and curved walls.

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Claims (8)

71 π? 9 Claims: '> yj c. c. ό A measuring device for measuring the pressure difference and the volume flow of a medium in a flow channel (16), the device comprising - an annular flow resisting plate (10) arranged substantially coaxially in the flow channel (16) so that an opening (A) remains inside the plate (10) ) and, on the other hand, an annular opening (B) between the outer circumference of the plate (10) and the inner surface of the channel (16), - at least two tubular members (12) or the like arranged substantially coaxially with the plate (10) on both sides and having several openings (13), such as relatively small holes or notches, for detecting the pressure on both sides of the plate (10), and - pressure measuring means connected to the tubular members (12) for measuring the pressure difference across the plate (10), characterized in that at least one of the tubular members (12) is at a certain distance (e) from the annular plate (10), each opening in this tubular member (12) ko (13) opens towards the ring plate (10). Measuring device according to Claim 1, characterized in that the two tubular elements (12) are at a certain distance (e) from the annular plate (10) (Fig. 3). Measuring device according to Claim 2, characterized in that the openings (13) in both tubular members (12) open towards the annular plate (10) (Fig. 3). Measuring device according to claim 1, characterized in that in the flow direction (F) the first tubular member (12) is at a certain distance (e) from the annular plate (10), while the second tubular member (12) is approximately attached to the annular plate (10) (Figs. 5). Measuring device according to Claim 4, characterized in that the openings (13) in both pipe elements (12) open in the flow direction (F) (Fig. 4). Measuring device according to Claim 4, characterized in that in the flow direction (F) the openings (13) of the first tubular member (12) open in the flow direction (F), while the openings (13) of the second tubular member (12) open in a direction transverse to the flow direction (F). Figure 5). Measuring device according to Claim 1, characterized in that the distance (e) is in the range from 30__ to 150% of the outer diameter of the pipe element (12). Measuring device according to Claim 7, characterized in that the distance (e) is of the order of 50% of the outer diameter of the pipe element (12). 7 Patent Scrap: 710 2 2