Patent GB-419472-A (GB)
Title: Improvements in and relating to means for controlling super-charged, or other high compression ratio internal combustion aircraft engines
IPC: F02D9/00
Filed: 1933-08-22
Abstract: 419,472. Regulating; spray carburetters. DODSON, E., 66, Lewin Road, Streatham, London. Aug. 22, 1933, No. 23328. [Classes 7 (iii) and 7 (vi).] Supercharged or other high compression-ratio aircraft engines, having a boost control with means for overriding said control, and an automatic mixture control for correcting the mixture supplied by the carburetter for changes in altitude, with means operable by the pilot's mixture control lever for changing the range of mixture strength, are characterized in that the pilot's throttle control lever is adapted to interengage the mixture control lever through means which ensures that when the pilot's throttle control lever is moved to its normal full throttle position the mixture control lever will not remain in a weak - mixture position. The throttle lever a and mixture control lever b, Fig. 1, are mounted in a casing c. Outside this casing the levers have respectively an arm a<1> connected through linkage d-d<2>, toggle d<3>, d<4> and arm e to the throttle valve e<1> and an arm bl connected by links g-g<2> to a ported sleeve valve g<3> mounted to slide between a piston valve g<4> and the ported casing g<5> of an automatic mixture control device. This device comprises an aneroid g<6> actuating a piston valve g<4> controlling, in a known manner, the pressure fluid to a servomotor piston g<7> connected to a valve g<12> controlling an air inlet to the carburetter fuel passage. The aneroid is carried on a follow-up device g<13> connected to the piston rod g<8> of the servomotor. The control levers work in gates a<2>, b<2>, Fig. 4, and three detents b<5>-b<3>, Fig. 2, are adapted to hold the mixture control lever b in position to give weak, rich and over-rich strengths. Movement of lever b to any of these positions actuates the sleeve valve g<3> which, in conjunction with inlet passage g<14>, transfer passages g<15>, g<16> and exhaust port g<17>, serves to move the servomotor piston g<7> in the appropriate direction to actuate the valve g<12>. The throttle lever a is held by a frictional device a<3>, Fig. 4, but can be moved to a slow-running position on the extreme left, a cruising position II, III, Fig. 6, a normal full open position on the right and, in an emergency, still further to the right by breaking a seal in an extension of the gate a<2> (Fig. 3, not shown). The mixture control lever b is connected at h<3> to an actuating lever h pivoted at h to the casing c and provided with an upward extension h<2>. The throttle lever a has projections a<5>, a<6> adapted to cooperate with the lever h, the projection a<6> being mounted on an extension beyond the pivot. The throttle lever is mounted on a shaft a<8> with arm a<1>, Fig. 4, and the mixture control lever on a coaxial sleeve b<7> carrying the arm b<1>. The Specification describes how, through interaction of the levers, the mixture control lever is moved to the over-rich position both when the throttle is moved to idling and to its emergency full-open position and further how, when the throttle lever is moved to fullopen position, the mixture lever is moved from its weak-mixture position. The mixture-control lever is connected to the mechanism for overriding the boost control. This control consists of a casing i, Fig. 8, communicating with the pressure side of the engine intake system, and containing an aneroid i<1> which through a servomotor actuates a link d<1> connected to the throttle-actuating toggle d<3>, d'. The aneroid may be overriden by depressing a cap i<2> by means of fingers i<5>, arm i<7>, link i<8> and arm i<@> fixed upon a shaft i<10> rotatable by an arm i<13> connected by link g, Fig. 1, to the mixture control lever. Another arm ill on shaft i<10> is connected to a lever i<15> for actuating a device i<14> controlling an enrichment jet for admitting additional fuel or an anti-detonant fluid. Overriding of the boost control increases the throttle opening and opens the enrichment jet. In a modified form of boost-control-override described with reference to Figs. 9-11 (not shown), the throttle-control toggle is replaced by two links pivoted to a floating lever, the fulcrum of which is carried by a bell-crank lever connected to the link from the boost control. Further, the mechanical means for overriding the boost control, are replaced by means in which the pressure in the casing i is varied by placing the casing in communication with the induction pipe at a point of low pressure by means of pipes under the control of an airleak valve forming part of a combined air-leak valve and enrichment jet.