FI62189C - pressure sensor - Google Patents

Description

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Patent- och reglsterstyrelsen Antakm utitgd oeh uti. ) (72) Riku Pauli Grönberg, Espoo, Finland-Finland (FI) (7l) Seppo Laine (5l) Pressure sensor - Tryckgivare

The invention relates to a pressure sensor for measuring the pressure difference, e.g. for measuring the volume flow of a duct flow.

Previously known volumetric flow measurement methods and devices require a virtually undisturbed flow profile at the measurement point in order for the measurement error to be small enough with a reasonable amount of work. 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 equalize. 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 which can be used to measure and adjust the volume flows of ventilation systems, even under disturbed flow conditions, with sufficient effort and with sufficient accuracy to the designed values.

Today, more than half of energy losses in buildings are 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.

With respect to the prior art of the present invention, reference is made to the applicant's earlier Fi Patent Applications Nos. 782384 (August 2, 1978) and 790235 (January 25, 1979). The object of the present invention is to further develop the measuring devices disclosed in the said Fi patent applications and to expand their field of application. The aim is to provide a simpler device than before, which is particularly suitable for valve-specific measurement in air-conditioning systems when calibrating various valves or pressure equalization boxes.

In order to achieve the above objects, the invention is mainly characterized in that two substantially annular tubular members are used as the flow channel pressure measuring means, the walls of which have small diameter holes and / or a corresponding gap or slots opening substantially perpendicular to the direction of the flow. pressure outside the duct.

In the following, the invention will be described in detail with reference to an embodiment of the invention shown in the figures of the accompanying drawing, to the details of which the invention is in no way limited.

Figure 1 shows a cross-sectional view of a pressure sensor according to the invention.

Figure 2 shows a section II-II in Figure 1 on a larger scale.

Figures 3 and 4 schematically show two different variations of the invention.

The pressure sensor according to the invention is placed, for example, in an air conditioning duct 10 through which the air flow F. Passes. The differential pressure sensor Δ p according to Figures 1 and 2 comprises two annular coaxial pipe members 12a and 12b, the inner 12a being fixed to the duct walls. The inner tubular member 12b is disposed in a wall groove 11 in the channel 10. The inner tubular member has evenly spaced sleeves 13 at regular intervals on both its outer and inner circumferences, which open substantially perpendicular to the flow direction F. Only the outer circumference of the outer tubular member 12b has a corresponding perforation 13. Said holes can be replaced by a corresponding slot or slots. Slots and holes can also be used together in a suitable combination.

62189 3

According to the figures, the flow passes through the central opening A of the inner tube member 12a and also from the annular space B between the tube members 12a, 12b.

According to Fig. 1, the pipe members 12a and 12b, which are e.g. plastic pipes, are connected to each other by a connector 15 and to a pipe 16 connected to a differential pressure measuring device. According to Fig. 1, a U-tube 17 is used as the measuring device for Aβ, the open end of which is affected by external pressure pu and the other end is affected by channel pressure 12a and 12b through the holes 13 through the holes 13. The difference in height of the U-tube 17 Δρ = py ± p.

According to Fig. 3, one annular tubular member 12 'having only small diameter holes 13 on its outer circumference is placed in the groove 11 of the channel 10'. pipe 10 "diameter. Each side of the tube member 12 "has a series of small diameter holes 13.

Above, the annular tubular members 12a, 12b, 12 ', 12 "are shown as circular as well as the channels 10, 10', 10". It should be noted, however, that the annular tubular members according to the invention may have other shapes, e.g. rectangular. The latter rectangular tube members are most preferably used to measure the flow of channels having a rectangular cross-section. Other types of polygonal or tubular members consisting of straight and arcuate parts are also possible within the scope of the invention.

The following are claims within the scope of which the various details of the invention may vary within the scope of the inventive idea.

Claims (3)

A pressure sensor for measuring a pressure difference and a fluid flow in a flow channel (10), the pressure sensor comprising - a first tubular loop (12b) arranged substantially coaxially in the flow channel (10) in connection with this inner wall and having smaller openings (13) in the wall which open substantially perpendicular to the flow (F), and - pressure measuring means (1T »1Ö) connected to the first pipe loop (12b) for measuring the difference between the internal and external pressure of the flow channel (10), characterized by a second pipe loop (12a), arranged in the flow channel (10) substantially coaxially with a first tube loop (12b) having a diameter smaller than the diameter of the first tube loop (12b), - with small openings (13) opening in the wall perpendicular to the flow (f) and connected to pressure measuring means (17) > 18). Pressure sensor according to Claim 1, characterized in that the openings (13) in the wall of the second tubular loop (12a) open radially both outwards and inwards. Pressure sensor according to Claim 1, characterized in that the second tubular loop (12a) is arranged substantially flush with the first tubular loop, so that an annular flow opening (B) is formed between the loops (12a, 12b). * +. Pressure sensor according to Claim 1, characterized in that the second pipe loop (12a) is fastened to the wall of the flow channel (10) by means of support members (1 * 0).