FLOW-MEASURING APPARATUS IN AIR VENTING AND CONDITIONING SYSTEMS

Abstract: A flow-measuring apparatus in ducts (1) of venting and conditioning systems, equipped with an hollow body (4) having a continuous slit in the direction opposite to the flow. In particular, this hollow body (4) is composed of a set of modular elements (5(n)) having a constant and elongated longitudinal section along the flow direction and that are made mutually intercommunicating and univocally connected to a sensor (S) connected in turn to a control logic (L).

Description: FLOW-MEASURING APPARATUS IN AIR VENTING AND CONDITIONING SYSTEMS The present invention refers to a flow- measuring apparatus inside a duct within air venting and conditioning systems in environments. An apparatus for detecting and checking the air flow along a duct substantially comprises measuring means connected to sensors that are able to detect the flow value in a certain duct section, computing means for comparing the measured value with a sample value and actuators comprising the members that are adapted to adjust the environmental conditions depending on the result of said comparison. Flow modifying effects in a duct induced by turbolence and uncontrolled flow deviations next to duct curves or branches, are known; the induced perturbation is also known that is induced by means such as the gates placed inside the duct to modify flow direction and intensity. In order to solve these inconveniences, flow detecting means are used that are able to locate the different flow conditions, being disturbed or not, and measure a meaningful and above all weighted value of the air flow intensity in a certain duct section. In other words, the measuring apparata within air venting and conditioning systems must be able to transmit, the flow values including the chaotic distribution of fluid threads along a duct length and in a certain section; in particular, they must be able to detect different values of the differential pressure, this meaning a meaningful quantity when flow speed conditions change, avoiding at the same time that a background noise and sound phenomena occur within the speed interval in which the system operates. The prior art is in particular contained in documents EP-A-0183987 and EP-A-0409779. The apparata disclosed in these patents allow measuring the flow based on the differential pressure value obtained by means of drilled tubular elements in different points of the duct section: - in document EP-A-0183987 the flow control technique is dealt with inside a duct of an air venting and conditioning system by means of measuring apparata connected to rows of blind tubular elements inserted in a star-like way transversally into the duct and respectively equipped with different openings oriented in an opposite direction to the flow and in a contrary or transverse direction to the flow; - in document EP-A-0409779 a flow measuring apparatus is disclosed that communicates, through two small channels, with an hollow ring- shaped and concentric body equipped with two chambers communicating with the duct volume through different openings that are respectively on the front and transverse side with respect to the flow. The common feature present in the above- mentioned apparata is the real value of the differential pressure which depends on the weighted contribution of the flow speed detected in the different openings along the tubular elements, being such differential pressure the meaningful quantity in the system controlling conditioning and venting. Within the above-described known prior art, a problem that often occurs is given by the scarce sensitivity of the measuring systems at low speeds, namely, the difficulty in discriminating the differential pressure values. Another problem is given by the difficulty in keeping low the sound level emitted by the control system parts that interact with the air flow at the different operating speeds. The apparatus of the present invention has been realised in order to improve the response of the differential pressure measuring system at low spe'eds . Moreover, the apparatus of the invention has been realised in order to obtain a flow-measuring apparatus that can be easily calibrated by operating on its geometry, thereby optimizing the sound response level without anyway modifying the differential pressure-detecting performance for which the apparatus is designed. This is a measuring apparatus that communicates, by means of two channels placed in succession along the flow direction, with an open hollow body in a direction that is respectively opposite and transverse with respect to the flow, whose feature is that this hollow body is composed of two elongated walls along the flow direction, being such walls joined by means of a diaphragm placed between these two channels, and that at least the opening along the direction that is opposite to the flow is composed of a continuous slit . The above and other objects and advantages of the invention, as will appear from the following description, are obtained by a measuring apparatus as claimed in Claim 1. Preferred embodiments and non-trivial variations of the present invention are claimed in the dependent Claims. The present invention will be better described, by some preferred embodiments thereof, given as a non-limiting example, with reference to the enclosed drawings, in which: Figure la shows an assembly view of the measuring apparatus in the duct section; Figure lb shows a cross-sectional view of the duct equipped with the hollow body on which the flow impinges; Figure 2a shows a longitudinal sectional view with respect to the flow direction of the hollow body limited by two walls and a diaphragm; Figure 2b shows the curved length of the hollow body composed of the interspace from whose external wall a protrusion containing the two connection channels with the measuring members transversally projects; and Figure 3 shows the cross-sectional views of the duct with the different arrangements of the hollow body as function of the sizes of the duct itself. With reference to the Figures, the flow- measuring apparatus of the invention substantially comprises a sensor S connected inside the duct 1 to_ an hollow body 4 through two channels 2 and 3 placed in succession along the flow direction. This sensor S in turn transmits the detected signal to a logic unit L connected to an actuator M that operates on the movement of a gate D or any other flow-adjusting element. This hollow body 4 is composed of a set of modular elements 5(1), 5(2), ..., 5 (n) , whose longitudinal section is constant and elongated along the flow direction. These modular elements 5 (n) are rectilinear elements with a suitable length according to the design that they must reproduce in the duct cross section. The typical shape of the cross section of these modular elements 5 (n) is an interspace formed by two walls 6 and 7 joined by a diaphragm 8 approximately at the height of a semi-chord subtending the two ends of these walls 6, 7. The diaphragm 8 has in its front end, in a direction that is opposite to the flow, a continuous slit 9 that is developed for the whole length of the element 5 (n) . The opposite end, along the direction that is parallel to the flow, is not necessarily equipped with the same above-described slit, being of 'the shape that is, according to the prior art, the closed one, suitably drilled, or open. The modular elements 5(n) are made mutually intercommunicating and univocally connected to the sensor S by means of junction elements 10 (n), 11 (n) , 12 (n) , depending on the junction of these modular elements 5(n) that is a connection with two channels, three channels, four channels or simply the continuity between two modular rectilinear elements next to the connection with the duct surface. These junction elements 10 (n) , 11 (n) , 12 (n) , being more or less curvilinear along the transverse duct plane, anyway comply with the continuity of the interspace delimited by the hollow body 4. At least one junction element of the type 10 (n) is equipped, in addition to the suitable securings to the duct wall, with the channels 2 and 3 realised astride of the diaphragm 8, complying with the intercommunicability condition of the "network" of elements composing the hollow body 4 with respect to the measuring element S. Figure 3 shows, in this respect, different types of arrangements of the modular rectilinear elements 5(n) joined according to different designs by means of ' the above-described junction elements 10 (n) , 11 (n) , 12 (n) . For example, the non-limiting shapes , shown in Fig. 3 are a set of quadrilaterals, each one having at least one side in common with the adjacent quadrilaterals, or a set of concentric quadrilaterals connected along their common diagonals . In particular, an interspace distribution is obtained along the transverse duct section that is able to define a continuous flow-measuring outline due to the slit 9 that is made a single entity by connecting the rectilinear elements 5(n) with the junction elements 10 (n), 11 (n), 12 (n) . The apparatus of the present invention efficiently reaches the objectives for which it has been realised: in particular, the branched arrangement of the multiple modular and junction elements intercommunicating and connected with the flow-measuring member allows the weighted measure of the pressure as function of the flow speed distribution in the duct section; the realisation of an outline equipped with a continuous slit at the opposite end to the flow direction allows improving the sensitivity in defining the flow characteristics at low speeds; such continuous slit as well can be easily modified in its geometry by operating on the edge thickness along the slit itself depending on the sound response optimisation. The apparatus of the invention has the further advantage of enabling a quick industrialisation: the linear elements are obtained by extrusion or pressing; the junction elements are obtained by pressing, suitably equipped in their junction points with the modular rectilinead elements with grooves or undercuts in order to guarantee an efficient connection.

Claims: CLAIMS Flow-measuring apparatus in ducts (1) of air venting and conditioning systems, of a type comprising a sensor (S) communicating by means of two channels (2, 3) placed in a succession along a flow direction with an hollow body (4) that is open along an opposite and transverse direction with respect to the flow, characterised in that said hollow body (4) comprises two elongated walls (6, 7) along the flow direction and a diaphragm (8) subtended between said two walls (6, 7) , thereby forming an interspace having at least one opening (9) that is similar to a continous slit. Flow-measuring apparatus in air venting and conditioning systems according to Claim 1, characterised in that said hollow body (4) is realised by joining different elements (5(n)) intercommunicating by means of junction elements (10 (n), 11 (n) , 12 (n) ) , a transverse section of said elements (5(n)) having the same geometric shape as the transverse section of said junction elements (10 (n), 11 (n) , 12 (n) ) . Flow-measuring apparatus in air venting and conditioning systems according to Claim 2, characterised in that said elements (5(n)) are of a rectilinear shape. 4. Flow-measuring apparatus in air venting and conditioning systems according to Claim 2, characterised in that said elements (5(n)) are of a circular shape. 5. Flow-measuring apparatus in air venting and conditioning systems according to Claim 2, characterised in that at least one junction element (10 (n), 11 (n), 12 (n) ) is integral with a wall of the duct (1) where said apparatus lies. 6. Flow-measuring apparatus in air venting and conditioning systems according to Claim 2, characterised in that a section of interspace delimited by walls of a junction element (10 (n), 11 (n) , 12 (n) ) communicates with the flow-measuring apparatus through two channels (2, 3) arranged astride of the diaphragm (8) joining the two walls (6, 7) . 7. Flow-measuring apparatus in air venting and conditioning systems according to Claim 1, characterised in that said hollow body (4) is developed along a cross section of the duct (1) realising a geometric shape that is approximately shaped as a quadrilateral. 8. Flow-measuring apparatus in air venting and conditioning systems according to Claim 1, characterised in that said hollow body (4) is developed along a cross section of the duct (1) realising a geometric shape that is shaped as a set of quadrilaterals, each one having at least one side in common with the adjacent quadrilaterals . 9. Flow-measuring apparatus in air venting and conditioning systems according to Claim 1, characterised in that said hollow body (4) is developed along a cross section of the duct (1) realising a geometric shape that is shaped as a set of concentric quadrilaterals connected along their common diagonals. 10. Flow-measuring apparatus in air venting and conditioning systems according to Claim 2, characterised in that the rectilinear elements (5(n)) are obtained by extrusion or by pressing. 11. Flow-measuring apparatus in air venting and conditioning systems according to Claim 2, characterised in that the junction elements (10 (n), 11 (n) , 12 (n) ) are obtained by pressing. 12. Flow-measuring apparatus in air venting and conditioning systems according to Claim 1, characterised in that an edge of each one of the two walls (6, 7) extended similar to a continuous slit is suitably calibrated in its thickness depending on a sound response optimisation of the apparatus onto which the flow impinges.

Inventors: DE MARTINO BERNARDINO, DE MARTINO, BERNARDINO
Applicants: DE MARTINO BERNARDINO, EDELWEISS ITALIA S R L, DE MARTINO, BERNARDINO, EDELWEISS ITALIA S.R.L.
Application year: 2001
Main classification: F24F11
IPC codes: F24F11, G01F1