GB1262771A - Fluid mixing device - Google Patents

Abstract

1,262,771. Mixing flowing fluids proportionately. ROBERTSHAW CONTROLS CO. 26 March, 1969 [27 March, 1968], No. 15911/69. Heading B1C. [Also in Divisions F2, G2 and G3] A mixing device for flowing gases or liquids comprises a venturiform mixing chamber 11 having an inlet 10 for a first fluid through a variable orifice 18, and an inlet 13 for a second fluid, which passes between a diaphragm 15 and seat 31 into the passage 32. The proportion of second fluid can be adjusted or its flow ousted by movement of the diaphragm relative to its seat by means of axial movement of the plunger 16. The diaphragm has a "pilot" aperture 42 and a "bleed" aperture 44 which allow fluid to pass through the diaphragm to equalize the pressure on its opposite faces; in operation the diaphragm remains spaced from the plunger on which there is no fluid thrust. As shown (in a device for mixing hot and cold water) the plunger actuating lever is controlled by a thermostat 87 and mechanism 86 to maintain the mixture temperature constant. The variable orifice 18 is an aperture in a resilient disc 17 and has an interchangeable backing ring 54 the shape of which determines its flow characteristics. In modifications the disc may have a plurality of radial slits (see Figs. 9, 10, 13 and 14, not shown) and may have a stamped backing and clamping ring (132, Fig. 18, not shown) the outer edge of which is curled round the rim of the disc. The flexible disc may be replaced by a flat spring cooperating with a fixed aperture (see Fig. 15, not shown) to form the variable orifice, or by a conical coil spring in which the orifice is constituted by the spaces between the convolutions (see Fig. 16, not shown). There may be more than two fluid inlets with more than one variable orifice.