Abstract: A fuel injection control apparatus for a diesel engine is provided which works to determine the number of a sequence of injection events to inject fuel into the engine in each operating cycle of the engine and increase it based on the temperature of an injector drive circuit. When the temperature of the injector drive circuit is relatively low, the apparatus increases the number of injection events to decrease the degree of combustion in the engine, thereby reducing the combustion noise of the engine.

Abstract: A fuel injection control apparatus for a diesel engine is provided which works to determine the number of a sequence of injection events to inject fuel into the engine in each operating cycle of the engine and increase it based on the temperature of an injector drive circuit. When the temperature of the injector drive circuit is relatively low, the apparatus increases the number of injection events to decrease the degree of combustion in the engine, thereby reducing the combustion noise of the engine.

Abstract: In a system in which a common rail accumulates fuel pressurized by a high pressure supply pump, when a pipe connected to the common rail is damaged or a pulsation of fuel injection is caused in the system, reliability of the system is greatly affected because of high pressure. According to the present invention, a mechanism to prevent leakage of fuel from the common rail even when the pipe is damaged, or a mechanism to damp a pulsation of fuel pressure, is provided in a pipe close to the common rail. Therefore, reliability of the system is improved.

Abstract: At diesel engine startup, a fuel injection control system for the diesel engine injects a pre-jet of fuel into a combustion chamber in synchronism with a signal indicative of an angular position of the crankshaft of the diesel engine. After the pre-jet of fuel has been injected, the fuel injection control system injects a main jet of fuel which is larger in quantity than the injected pre-jet of fuel. Even when the engine rotational speed is low and subjected to variations as at engine startup, the pre-jet of fuel is reliably injected into the combustion chamber at a desired time. The pre-jet of fuel which is injected and ignited prior to the main jet develops an easily ignitable, activated condition in the combustion chamber. The subsequently injected main jet of fuel can thus be easily ignited by the activated condition in the combustion chamber. The diesel engine can be started quickly and smoothly without fail.

Abstract: A fuel injection control system for internal combustion engine comprises a fuel injection pump including a plunger slidably reciprocating in synchronism with rotation of the engine and a spill port establishing communication between a low pressure chamber and a pump chamber. An electronic control unit is responsive to engine operating conditions for the determination of fuel injection time period and controls the solenoid-operated valve to close the spill port in response to the requirement of fuel injection into the cylinder and open the same to terminate the fuel injection. The fuel injection control system further comprises a circuit including two fixed resistors and two adjusting resistors so that first and second voltage signals are developed at its terminals. The two adjusting resistors respectively determine the value of the voltage signals.