Patent GB-448931-A (GB)
Title: Improvements in and relating to the fuel-supply controls of internal-combustion engines
IPC: F02D17/00
Filed: 1934-12-15
Abstract: 448,931. Controlling motor vehicles. SMART, A., College Avenue, Newcastle-on- Tyne. Dec. 15, 1934, Nos. 36056 /34, 2642 /35, and 16386/35. [Class 79 (v)] [See also Groups XXVII and XXXVII] In order to prevent waste of fuel in motorvehicle engines when the throttle valve is in idling position and the vehicle is overrunning the engine, means are provided for completely shutting off the supply of combustible mixture or fuel, and for admitting air in place thereof, when the abovenamed conditions occur, and also for restoring the supply of sufficient mixture to prevent the engine from stalling if the power transmission should be declutched, or if the engine speed should fall to idling speed. The restoring-means may be actuated mechanically by the clutch pedal, or by the speed governor, or electromagnetically in accordance with the positions of the accelerator and clutch pedals, or by the suction in the induction pipe. Fig. 3 shows one form in which the accelerator pedal is connected by a rod f and lever d to the throttle valve a, which closes completely when the pedal is released, the lever d opening an extra-air valve p as shown. The clutch pedal is connected by a rod m to a pivoted stop engaging the lever d so that when the clutch is put out of action, the stop g is pulled against the action of a spring j so as to move the lever d sufficiently to open the throttle a little and close the air valve p. In a modification, the stop g is provided with a torsional spring at its pivot, and its movement is limited by an adjustable screw stop. Fig. 7 shows another device in which a byepass t is provided around the throttle a, and is controlled by a valve u pressed open by a spring v and connected by a cable y to the speed governor of the engine. If the engine speed exceeds the idling speed, the valve u is closed and the mixture supply completely cut-off, an air-inlet valve p then being opened by the engine suction. Fig. 8 shows the electromagnetic control, comprising an electromagnet 17 which actuates an additional throttle 11 placed on the engine side of the normal throttle, and also an extra-air valve. The magnet is connected as shown to an earth point 64 and to the terminal 27 of an interlocking switch, which has another terminal 28 connected through a master switch 30 and fuse 31 to the vehicle battery 32, and a third terminal 33 connected through the coil of a solenoid 35 to one terminal 36 of a two-way switch, which has a common terminal 37 connected to earth and its other terminal 39 connected through the coil of another solenoid 41 to the terminal 27. The coil of the solenoid 41 is also connected to the terminal 43 of a one-way switch having an earthed terminal 44, and the solenoids 35, 41 have their armatures 62, 63 connected to fingers 60, 61 which coact with spring contacts 58, 59 in such a way that when one contact is open the other is held closed. The one-way switch has an arm 49 co-operating with the clutch lever 48, and the two-way switch has a lever 51, 52 co-operating with the accelerator pedal 53, the arm 51 having projections 50 which coact with spring contacts 55, 56, 57. The spring 55 is bowed so that it remains in either the raised or depressed position until forcibly moved. During normal running, the parts are in the position shown, with the throttle 11 open and the air-inlet valve closed. When the accelerator pedal 53 is released, it operates the arm 52 to connect contacts 55, 56 so as to energize the solenoid 35 which closes contact 58, thus energizing the magnet 17 to close the throttle 11 and open the extra-air valve. The contact 59 is released and breaks the circuit of the solenoid 35, but the contact 58 is held closed by the interlocking-fingers 60, 61. If the accelerator pedal 53 is depressed, or the clutch lever 48 is moved to disengage the clutch, the circuit of the magnet 17 is broken and the throttle 11 again opened. Instead of operating the additional throttle 11, the magnet 17 may completely close the normal throttle, or may actuate a supplementary valve to cut off the supply of fuel to the carburetter jet. Fig. 10 shows the suction-actuated form, in which the additional throttle 11 is actuated by a spring- pressed piston 72 which also controls an air inlet 75. The upper side of the piston 72 is connected to a double-beat valve 80 which is actuated by a diaphragm 96 controlled by springs 99, and controls communication with a chamber 84 connected to the induction pipe, or a passage 83 leading to an air valve 87 controlled by a lever 91 on the spindle of the normal throttle a. During normal running, the piston 72 is raised and the throttle 11 held open, while the air inlet 75, 76 is closed When the accelerator pedal is released, the throttle a assumes the idling position as shown, and the valve 87 is opened to admit air below the diaphragm 96, the upper side of which is subject to the suction in the induction pipe. The springs 99 are so adjusted that, when the engine exceeds idling speed, the diaphragm 96 is raised so as to lift the valve 80 and admit air to the piston 72, which is thereby lowered to close the throttle 11 and admit extra air at 75. In a modification of the suction-actuated apparatus, the supplementary throttle 11 and the air valve 87 are dispensed with, the throttle a being completely closed when the accelerator pedal is released, and a stem-like extension of the piston 72 controlling a byepass around the throttle. Alternatively, the diaphragm 96 may control a valve in the fuel supply to the carburetter jet.