Fuel injection pump for an internal combustion engine

Claim 1

A fuel injection pump for an internal combustion engine having a cylinder provided with a suction passage and a suction port, a piston rotatably and reciprocally received in the cylinder, a compression chamber enclosed by the cylinder and the piston, and the suction port being open during the suction stroke to the compression chamber and being closed during the compression and injection stroke of the piston, the improvement comprising: an electromagnetic valve installed in said suction passage leading to the suction port for controlling the fuel supply into the compression chamber, and a controller connected to said valve for controlling said valve to open during idling operation of the engine at a lower frequency than that in ordinary operation and for a longer period of time to supply enough fuel to keep the temperature of the combustion chamber high to thereby decrease the stimulus odor of the exhaust gas, said controller including means for generating a signal corresponding to a suitable fuel injection time for each cylinder of the engine in accordance with the engine revolution, a flip-flop circuit connected to said signal generating means for dividing the frequency of said generated signal by one-half, a monostable multivibrator connected to said valve for controlling the energization of said valve, a variable resistor connected to said multivibrator for varying the output pulse width of said multivibrator in accordance with the position of the accelerator, a second variable resistor connected to said multivibrator for varying the output pulse width of said multivibrator by manual operation, a switch for connecting said generating means to said multivibrator directly in ordinary operation of the engine and through said flip-flop circuit in idling operation thereof, and a second switch for connecting said multivibrator to said variable resistor in ordinary operation of the engine and to said second variable resistor in idling operation of the engine.