Patent GB-394020-A (GB)
Title: Improvements in or relating to control mechanism for carburettors of internal combustion engines
IPC: F02M1/00
Filed: 1932-08-12
Abstract: 394,020. Spray carburetters. ASSOCIATED EQUIPMENT CO., Ltd., Windmill Lane, Southall, Middlesex, and OTTAWAY, E. C., 5, Lyndhurs.t Avenue, Tolworth, Surrey. Aug. 12, 1932, No. 31382/31. [Class 7 (iii).] The carburetter has a light and a heavy fuel supply, the change-over from the one to the other being effected, according to the temperature of the engine, by a thermal device comprising a vessel containing a volatile liquid in communication with an extensible device such as bellows acting either directly or through relay mechanism. A light fuel chamber 24 supplies a jet 37 and a heavy-fuel chamber 23 a jet 36, the jets having known aerating means, and their outlets controlled by valves 42, 41 adapted to be actuated by a lever 54 pivoted at 53. The aerated fuel from the jets 36, 37 passes by way of ducts 43, 44, 60, 61 to an annular space 59 around a choke tube 58, Fig. 3, and then to nozzles 57. The valves 41, 42 are loaded by springs 49, 50 and are adapted to be actuated by adjustable screws 55, 56 at the ends of the lever 54. The mixture flow to the engine is controlled by a throttle valve 62, Fig. 3, an elbow passage 65 in which communicates through duct 71 and passages, to which air may be admitted, Fig. 6 (not shown), with the float chamber. When using heavy fuel, extra air may be admitted to prevent deposition of fuel in the induction pipe by means of a spring-loaded valve 80, Figs. 3 and 4, which communicates with the engine side of the throttle valve through a duct 75. The valve is loaded by an adjustable spring 87, Fig. 4, acting upon a lever 85 pivoted at 86, the outer end of the lever bearing on the valve spindle 82. The spring is inclined to the valve stem so as to produce a constant load on the valve. The thermal device comprises a phial 91, Fig. 3, connected through a tube 94 to an expansible bellows 92 which, together with the phial, contains a volatile liquid. The phial is preferably inserted in a recess in a combined induction and exhaust pipe, Fig. 7 (not shown). The bellows is supported by a casting 100 secured to the carburetter casting by studs 102. The pipe 93 is formed with or attached to a plate 104 forming the lower part of the bellows and is secured by a nut 105 The upper end of the bellows is secured to a plate 106 connected by rods 108 to a plate 109 loaded by a spring 111 bearing at its upper end against an adjustable screwed ring 112. A projection 107 on the upper plate 106 bears against a cupped end 116 of a lever 117, the other end 119, Fig. 5, of which is cupped to engage a plunger 120 which, through a plate 121, spring 124, plug 125 and adjustable screw 127 actuates a lever 128, the other end of which engages an apertured boss 130, Fig. 2, in the lever 54. Hence, as the bellows become expanded the lever 54 is moved to close the light fuel valve 42 and open the heavy fuel valve 41. To prevent knocking when working with a light fuel, it is desirable to curtail the flow of mixture and this is effected by interposing a stop, formed as a plunger 132, Fig. 9, in the path of the throttle valve lever. A screw 139 on lever 128 is adapted to actuate an arm 137 of a lever, the other arm 136 of which determines whether the plunger rod 132 shall be interposed in the path of the throttle lever arm 131 or not. In a modification, Fig. 11, the phial is connected by a tube 94 to bellows 142 in a casing 143, the bellows being loaded by a spring 111 located between a member 147 on the bellows and an adjustable ring 149. In this construction the levers 117, 128 are dispensed with, the lever 54 which actuates the fuel valves being moved by a piston, Fig. 10 (not shown), subject to the suction in the induction pipe. The cylinder in which the piston moves communicates with the induction passage through a pipe 156, Fig. 11, valve 159 and duct 158. The valve is opened at the desired temperature to change the fuel by the bellows 142 acting through a two-armed lever 168, 169, loaded by springs 175. The member 147 has a boss 163 to receive a stud 164 on which can slide a flanged sleeve 166 carrying near its upper end two nuts 167 locked together to form a stop. The arm 169 of the lever engages a bobbin 172 on the valve stem 161, and the arm 168 lies between the nuts 174 and the flange on sleeve 166. A permanent magnet 199 co-operates with an armature 200 on the arm 169 to held the lever in the position corresponding to an expanded bellows. In a further modification, Fig. 12 (not shown), the valve corresponding to 159, Fig. 11, is double seated and may place the cylinder either in communication with the induction passage or with the atmosphere. In a still further modification, Fig. 13, the thermally sensitive device closes a switch which brings a solenoid into action to effect the change-over. The solenoid 184 is carried by a bracket 183 and has a plunger 216, actuated by an armature 190, and adapted to move the change-over lever 117. The terminals 192, 193 are connected through a battery and main switch unit 212 and leads 213, 214, to the contacts 207, 208 of a switch 206 adapted to be closed by an arm 201 actuated by the thermal device 196 through a plunger 203. A permanent magnet 199 co-operates with an armature 200 carried by the arm 201. The phial 91 containing the volatile liquid is connected by tube 94 to bellows in a casing 196 which is connected to additional bellows in a casing 198, the function of which is to allow for further increase in the volume of the volatile liquid after the change-over lever has been moved.