Patent GB-890443-A (GB)
Title: Thermostatic fluid mixer
IPC: G05D23/13
Filed: 1958-12-29
Abstract: 890,443. Fluid-pressure servomotor-control systems. TRUBERT, M. Dec. 29, 1958, No. 4l896/58. Class 135. A thermostatic mixer for hot and cold fluids comprises an open-fronted body 101 having first and second inlets 104d, 104g for hot and cold fluid respectively, an outlet 107 for mixed fluid, first and second inlet chambers in the body communicating with the respective inlets and a mixing chamber communicating with the outlet 107 and with the inlet chambers through first and second apertures 105d, of which only one is shown, these apertures being aligned in a plane parallel with the plane of the open front of the body 101, a replaceable valve assembly interposed in the body between the inlet chambers and the mixing chamber and including first and second main valves associated with the first and second apertures 105d, and controlled automatically by a rocking pilot valve 154 actuated by a thermally responsive element 155 in the mixing chamber, and a detachable cover 110 for the open front of the body 101 which retains the valve assembly in fluid-tight engagement with a part of the body surrounding the apertures 105d. As shown, the device comprises a symmetrical arrangement of two diaphragm type regulating and fluid proportioning valves 145d for fluids of different temperatures which enter the body 101 through the respective inlet connection 104d, 104g. These connections lead through the inlet chambers as shown to the inlet apertures 105d in the body which are provided with shoulders 106d in a plane parallel to that of the detachable cover 110. The valves are comprised in a detachable unitary structure which is secured in the. body against the shoulders 106d by application of the cover 110. This unitary structure comprises a base-plate 129 having a pair of upstanding annular walls 130d provided with apertures 138d opening into the interior of the body 101 on the outlet side of the diaphragm valves. Beneath each aperture is a screwed-in perforated valve seat 137d of the diaphragm valve. This seat carries an upper funnel-shaped inlet member 149d which registers with the body inlet opening 105d and has a sealing ring 152d pressed into engagement with the shoulder 106d when the cover 110 is secured by screws 108. A control pressure chamber 135d formed beneath the diaphragm is open through a fixed orifice 146d to the pressure of fluid entering the funnel-shaped inlet member 149d, and a pair of variable outlet orifices 143d, 143g, one opening from each chamber into a central space between the respective annular walls are differentially controlled by a common pilot valve member 154 hingedly mounted between these opposed orifices. This pilot valve member has a ball-and-socket actuating connection with a bimetallic strip 155 disposed in the interior of the body and resiliently carried from the base-plate 129. The bimetallic strip carries an adjustable bearing arm 164 bears on a setting pin 178 movable by a dialtype setting knob 180. Zero adjustment is effected by an adjustment pin 183 which is movable into operative engagement with an adjusting screw 164 connecting the bearing arm 164 with an integral extension part 159 of the bimetallic strip.