Patent GB-1192201-A (GB)
Title: Improvements in Electronic Injector Devices and in Injectors Employed with these Devices
IPC: F02P7/03
Filed: 1967-04-13
Abstract: 1,192,201. Transistor pulse circuits. SOC. DES PROCEDES MODERNES D'lNJECTION SOPROMI. 13 April, 1967 [13 April, 1966; 2 Dec., 1966; 9 Dec., 1966], No. 17094/67. Heading H3T. [Also in Divisions F1 and G1] A variable pulse width bi-stable, Fig. 12, controlling fuel injection to an I.C. engine comprises complementary transistors 705, 710, the start of a pulse being produced by a positive step at an input capacitor 700 (from one of a plurality of magnetic reed switches associated with engine rotation), and the pulse being terminated by a negative pulse at 809 from a delay circuit incorporating a unijunction transistor 805. Commencement of the delay is a step at 800 due to starting of the bi-stable pulse, and duration is controlled by varying resistor 803, or by varying the frequency of a pulse train applied to capacitor 806. The pulse train is produced by an oscillator, Fig. 25, wherein a positive voltage on the input resistor 101, supplied from the point 800 of the bi-stable, enables a unijunction 121 and a complementary pair 109, 116 to oscillate, the complementary pair constituting a monostable, and the unijunction a source of trigger pulses produced by virtue of the time constant 101, 102. In a modification of the oscillator (Fig. 26, not shown) a second unijunction (104) provides a second unijunction (140) provides a second trigger pulse and the complementary pair operates as a bi-stable. Duration of the delay produced by unijunction T805 may be achieved alternatively by varying the voltage applied to its base resistor 804, this being achieved for: Engine temperature: by means of a thermosensitive transistor, (823, Fig. 17, not shown) whose base current varies with temperature and varies the voltage applied to resistor 804; Air temperature: by a similar further transistor (830, Fig. 18, not shown); and Rate of depression of accelerator pedal: by connecting to the pedal the wiper of a potentiometer (838, Fig. 19, not shown), connected with a series capacitor (836) in the base circuit of the transistor (823). Energy conserving arrangements (Figs. 37 to 41) in the injector solenoid operating circuits utilize diodes and capacitors connected across the solenoids to convey the energy dissipated upon de-energization of one solenoid to assist in energization of the next solenoid, the capacitors associated with successive solenoids being cross-coupled to achieve this end. One embodiment (Fig. 43, not shown) employing one transistor (713) to drive all solenoids utilizes only one energy conserving capacitor (5001) for all solenoids, a further thyristor (5002) being provided to appropriately switch this capacitor. The injector solenoids are turned off in one embodiment by extinguishing thyristors (4028, 4029) one of which is associated with one set of solenoids and the other with a second set; these thyristors are fed with energy which is stored on capacitors connected to their anodes and derived through diodes also connected to their anodes from other storage capacitors connected across the respective sets of solenoids.