GB902072A - Improvements in or relating to fuel injection systems for internal combustion engines - Google Patents

Abstract

902,072. Electric control systems. BOSCH G.m.b.H., ROBERT. Dec. 4, 1958 [Dec. 7, 1957], No. 39078/58. Class 40 (1). [Also in Groups XXVII and XL (c)] The fuel injection valve of an I.C. engine is opened during the unstable state of a monostable transistor flip-flop circuit which is changed over once per revolution for each cylinder by a cam driven by the engine shaft, and returns to its stable state after a time period determined by the position of the throttle lever, the speed of the engine, and the temperature and pressure of the air. As shown (Fig. 1), the valve cone 35 of a fuel injection valve 33 is raised to allow fuel to be injected into the intake pipe 30 of an I.C. engine 10 when coil 34 is energized by the output of an amplifier 28, which occurs when normally conducting transistor T2 is cut off by transistor T1 conducting after switch 39 has been closed by cam 38 driven by the motor shaft 11. The duration of the cut-off is determined partly by the discharge time of capacitor 58 through its shunt resistors 59, 60, resistor 59 being sensitive to atmospheric temperature and pressure, and partly by the collector voltage of transistor T1, controlled by the regulator unit 41, which comprises a 1000 c.p.s. generator 70 whose rectfied output is fed to the collector of transistor T1 through a fixed coil 72 and a rotatable coil 71 giving variable coupling. The motor shaft 11 drives a cylindrical permanent magnet 74 located inside a metal cup 75 to an extent determined by the throttle lever 82. Thus, the drag on the cup 75 is controlled by the throttle lever 82, which also controls the engine speed, and the cup 75 rotates together with coil 71 against a control spring 84, varying the proportion of the output of generator 70 fed to the collector of transistor T1 after rectification at 76.