Patent GB-262888-A (GB)
Title: Improvements in or relating to carburettors for internal combustion engines
IPC: F02D9/00
Filed: 1925-10-08
Abstract: 262,888. Dodson, E. Oct. 8, 1925. Spray carburettors.-A carburettor particularly for use with aeronautical engines employing supercharging or having a higher compression ratio than usual, comprises two or more mixture passages and throttle valves therein so interconnected that they commence to open one after another but become fully open together, and in which the second throttle to come into action is adapted not only to limit the charge weight in accordance with the altitude attained, but to limit the mixture strength with the object of preventing damage to the engine due to excessive throttle opening. This is effected by employing in conjunction with said second throttle either a weak mixture supply, or by connecting it to an altitude control device of the kind that. on being opened, tends to weaken the mixture either by admitting air to the emulsion passage' or by controlling the suction in the top of the float chamber. The primary mixture passage 2 is controlled bv a throttle valve 4 and the secondary passage 5, supplying a weak mixture, by a throttle valve 7. An arm 9 on the throttle 4 is directly connected to a rod 8 actuated by the pilot and is also connected through a link 10 and a lost motion pin-and-slot device 14, 15 to an arm 11 fixed to the spindle 12 of the altitude control device. Another arm 16 on the spindle 12 has holes 17 to any one of which is connected a link 18 the other end of which has a pin-andslot connection 19, 20 with the fulcrum of a floating lever 21, the fulcrum being guided by the' .end of a link 22 hinged to a fixed pivot 23. One end of the lever 21 is hinged at 24 to the rod 8 and the other end has, integral with it, a curved portion 25 connected by a link 26 to an arm 27 on the spindle of the throttle valve 7. The connection between the parts 25, 26 is by means of a pin 28, slot 29 and one of a number of holes 30. An independent control rod 31 is connected to one of the holes 32 on the arm 11 and when the arm 16 and link 18 are in a straight line, as shown, the altitude control may be rotated to a sligfht extent without affecting the throttle valve 7, if 'the lost motion devices are not at the limit of their travel. A tension spring 34 acting on an arm 33 keeps the throttle 7 to the position permitted by the pin-and-slot devices. The floating fulcrum for lever 21 provides a differential control effect for the two throttle valves, and the lost motion at 28 in conjunction with the holes 30 provides for phase differences in the throttle openings. Movement of the altitude control effects through link 18 a movement of the throttle 7. The drawing shows the approximate positions of the parts for flying at an altitude of say 30,000 feet and the Specification describes what manipulations are necessary (1) to effect a dive, (2) to return suddenly to full power, (3) to cruise at the reduced height, and (4) to land. In a modified construction, Figs. 2, 3, 4, the twin carburettor 35 has brackets 38 carrying a shaft 39 to which are secured arms 40, 41, actuating the throttle spindle 36, 37 of - the normal and weak mixture passages respectively, by the linkages 42 - - 49 shown in Figs. 8 and 4. The altitude control device 50 is not interlinked with the throttle mechanism but its shaft 51 carries a bevel wheel 52 engaged by a sector 53 the hub 54 of which is looselv mounted on shaft 39 and carries a control arm 55. This arm has a projection 56 adapted to be engaged by a projection 57 secured to the shaft 39. If the supercharging blower fails the mixture strength may be maintained by providing a supplementary fuel nozzle. High compression engines may have the valve timing means connected to the throttle or the altitude control. Specification 209,515 is referred to.