DEVICE FOR MEASURING THE FLOW RATE OF A FLUID IN A CONDUIT

The device (1) for measuring the flow rate comprises an impeller (10) to be rotatably mounted in said conduit (C), around an axis (X-X) and having a plurality of radial vanes (13) to be hit by a flow of said fluid for making the impeller (10) rotate with an angular speed which is a function of the flow rate of said fluid, and a detector (16, 17) associated with the impeller (10) to provide signals indicating the angular speed thereof. Upstream of the impeller (10) a diffuser (20) is provided defining a plurality of passages (21, 22) for dividing said flow into a plurality of reduced flows and directing said reduced flows toward the vanes (13) of the impeller (10), such as to make the latter rotate in a predetermined direction. The impeller (10) has a first axial portion (10a) close to the diffuser (20) and provided with blades (13), which are flat and lie in radial planes relative to the axis (X-X), and a second axial portion ( 10b) away from the diffuser (20) and provides a greater radial dimension than the first axial portion (10a), and to which the detector (16, 17) is associated. The diffuser (20) forms peripheral passages which extend in planes parallel to said axis (X-X) and inclined in a same direction about said axis (X-X); each passage (21, 22) having a longitudinal inlet portion (21), parallel to said axis (X-X) and a transverse outlet portion (22) laterally facing said first axial portion (10a) of the impeller (10) such that in operation, the outlet portions (22) of said passages (21, 22) direct towards the vanes (13) of the impeller (10) corresponding flows or jets of fluid in non-radial directions inclined in a same direction around said axis (X-X).The device (1) for measuring the flow rate comprises an impeller (10) to be rotatably mounted in said conduit (C), around an axis (X-X) and having a plurality of radial vanes (13) to be hit by a flow of said fluid for making the impeller (10) rotate with an angular speed which is a function of the flow rate of said fluid, and a detector (16, 17) associated with the impeller (10) to provide signals indicating the angular speed thereof. Upstream of the impeller (10) a diffuser (20) is provided defining a plurality of passages (21, 22) for dividing said flow into a plurality of reduced flows and directing said reduced flows toward the vanes (13) of the impeller (10), such as to make the latter rotate in a predetermined direction. The impeller (10) has a first axial portion (10a) close to the diffuser (