GB1122263A - Variable flow metering devices - Google Patents

Abstract

1,122,263. Valves. JOSEPH LUCAS (INDUSTRIES) Ltd. 14 July, 1966 [22 April, 1965], No. 16934/65. Heading F2V. [Also in Division F1] The invention relates to a variable flow fluid metering device such as used in gas turbine engine fuel systems. In the fuel metering device shown, a pair of axially spaced fixed sleeves 12, 13 are provided and an axially and rotatably movable tubular member 10 is disposed within the fixed sleeves. A movable sleeve 11 is mounted on the inner tubular member 10 between the fixed sleeves 12, 13 and defines therewith two axially-variable annular fuel metering orifices. The inner tubular member 10 is formed with two metering orifices 10a, 10b of triangular form, the base of the triangular orifice 10a being smaller than that of the orifice 10b. The triangular orifices 10a, 10b co-operate with the annular orifices between the sleeves 11, 12, 13 to form fuel metering orifices of variable area through which fuel flows into the space within the inner tubular member 10. The adjacent ends of the sleeves 12, 11 and 13 are chamfered such that the radial depth of the ends of the sleeves 11, 13 adjacent the triangular orifice 106 having the greater base length is less than the radial depth of the ends of the sleeves 12, 11 adjacent the triangular orifice 10a having the lesser base length. The arrangement is such that when the spaces between the movable sleeve and the respective fixed sleeves are equal, the relationship between the exposed areas of the openings and the radial depth of the sleeve ends tends to create a balance of the forces acting axially upon the movable sleeve at opposite ends thereof.