GB893873A - Improvements in and relating to flow meters - Google Patents

Abstract

893,873. Measuring fluid flow. GLOSTER AIRCRAFT CO. Ltd. Nov. 25, 1958 [Dec. 2, 1957], No. 37545/57. Class 69 (1). [Also in Groups XXXV and XXXVIII] The rate of flow of fluid in a duct is measured by means of an impeller which imparts a tangential velocity to the fluid and a member downstream of the impeller which moves in response to the tangential velocity, the impeller having a magnetic member co-operating with a permanent magnet adapted to be rotated by a drive means. In Fig. 1 the duct comprises two members 1, 2 held together by fluid-tight seals and contains a turbine 11 and an impeller 10 on a support 9. The impeller is driven by an A.C. motor 14 in a fluid-tight casing, the drive being communicated by a magnetic coupling comprising a rotating cylindrical magnet 19 and a plurality of magnetic members 23, 24 attached to the impeller. Fluid enters at the right-hand end, passes through ducts 25 and is discharged from the impeller at an angle so that its velocity has a tangential component. The issuing fluid exerts a force on the turbine 11 against a biasing spring 29 and turns it through an angle depending on the mass rate of flow. The angle is measured by magnetic members 32 co-operating with solenoids 33 (see Group XXXVIII). To prevent hydraulic coupling between the impeller and the turbine, the fluid is constrained to flow in an annular path between an outer baffle 20 fixed to the casing and an inner baffle 31 on the turbine. The impeller shaft also carries a tachogenerator whose output serves to maintain the impeller speed constant. In an aircraft installation (Fig. 2, not shown) the outputs from two such flowmeters are passed to individual indicators and to a combined indicator to show the rate of flow and total flow for each engine and for both engines respectively. In a modification the torque input to the impeller is measured in terms of the deflection of a spring coupling in the drive thereto. A slightly different arrangement of the parts appears in Fig. 1 of the drawings accompanying the Provisional Specification (not shown here).