Patent GB-649991-A (GB)
Title: Improvements in or relating to ignition controlling apparatus for internal combustion engines
IPC: F02P5/10
Filed: 1948-02-26
Abstract: 649,991. Timing ignition; spray carburetters. BENDIX AVIATION CORPORATION. Feb. 26, 1948, No. 5820. Convention date, Feb. 6, 1941. [Classes 7 (iii) and 7(iv)] Ignition timing is controlled by a timing setting device responsive to engine suction and requiring a suction of a predetermined value to actuate the device, the device being so connected with the engine intake that when the throttle valve is in its substantially closed or idle position engine suction of a value just below that required to actuate the setting device is transmitted thereto and when the throttle valve is initially moved from the idle position and is within a predetermined range of movement the suction transmitted to the device is suddenly and substantially increased and-when the throttle valve is opened further than the predetermined range of movement the suction transmitted to the device is suddenly modified. According to another feature of the invention a plurality of control passages are connected to the setting device and open into the intake conduit adjacent the throttle valve the passages being so arranged that one control passage is in communication with a region posterior to the throttle valve at all positions thereof and the other control passages communicate with regions on one or the other side of the throttle valve in accordance with the selected position of the valve. As shown (Fig. 2) a throttle body section 30 of a carburetter includes a passage 74 which communicates by means of a pipe 20 with a chamber 66 at the left-hand side of a diaphragm 23, the diaphragm being connected by means of a rod 22 to a spark timing lever of a distributer (not shown). The passage 74 also communicates by means of two ports 78 (one only of which can be seen) and by means of an impact tube 82 with the carburetter induction passage. The throttle valve 44 is shown in the idling position and the engine suction acting in the passage 74 is reduced by air from the ports 78. However, as soon as the throttle valve is opened beyond the idling position the high suction on the engine side of the throttle valve acts through the ports 78 and through the medium of the diaphragm 23 advances the ignition timing. When the throttle reaches a halfopen or any other desired position indicated at 44b the end of the tube 82 is stated to become exposed to the impact of the air flowing through the induction passage and air is thus bled into the passage 74 to reduce the suction and retard the ignition. There may be only one port 78 or more than two such ports. This single port may be constituted by a narrow slot. The area of an orifice 86 in the tube 82 may be half that of the ports '78. A spring 68 is designed to yield to suctions on the diaphragm above approximately three inches of mercury. and a stop member 69 on the diaphragm limits the advance of the spark when a suction of approximately 14 inches of mercury or over is applied to the chamber 66. In a modification there is one port on one side of the induction passage which is located just anterior to the edge of the throttle valve, when it is in the idling position, and two further ports on the opposite side of the induction passage, all the ports communicating with the passage 74.. The effect is the same as previously described, the ignition being retarded when the throttle is opened to such a position that the two ports on one side are acted on by pressure anterior to the valve. In another modification, Fig. 5, a port 122 communicates through a passage 124 with a duct 102 connected to the passage 74 and a further port 126 communicates with the duct 102 through a passage 128 controlled by a non-return valve 130. When the throttle valve is opened from its idling position high suction acts through the port 120 to advance the ignition. On further opening movement of the throttle the port 122 becomes uncovered and air bled in through this port retards the ignition. A further opening of the throttle valve to a position 44g uncovers the port 126 and air is then bled into the passage 74 through both this port and the port 122 to further retard the ignition. The port 126 preferably has a somewhat greater effective area than port 122 and the ports may be substantially the same distance from the throttle valve. A conventional centrifugally controlled mechanism may be used to vary the ignition timing according to speed. The invention is applicable to carburetters having an upward or a horizontal delivery. In a modification of Fig. 2 the tube 82 is replaced by a horizontally disposed tube having its outlet facing in the direction of flow of the incoming mixture. Thus above a predetermined opening of the throttle valve the flow of air provides additional suction to the passage 74 and advances the ignition relative to the adjustment that would other wise be effected.