Fuel injection control apparatus with forced fuel injection during engine startup period

A fuel injection control apparatus for an internal combustion diesel engine which is started by an engine starter, comprising:

• engine operating parameter detecting means for detecting operating parameters of said engine, the operating parameter detecting means including an engine speed sensor which generates by electromagnetic induction an engine speed indicating sinusoidal signal having a frequency indicating the speed of said engine when said speed is higher than a predetermined speed value and an amplitude variable as a function of the speed of said engine when said speed is lower than said predetermined speed value and a substantially constant amplitude when the engine speed is higher than said predetermined speed value;
• fuel injection quantity of calculating means for calculating the quantity of fuel to be supplied to said engine in accordance with said detected operating parameters of said engine;
• engine start detecting means for detecting when said engine starter is being operated and generating an output signal indicating the operation of said engine starter;
• verifying means for verifying that said speed indicating signal is valid or invalid depending on whether said amplitude is higher or lower than a predetermined threshold, respectively;
• and
• fuel injection control means for effecting the injection of fuel in accordance with the calculated fuel quantity when said speed indicating signal is detected as being valid and forcibly effecting the injection of a fixed amount of fuel when said speed indicating signal is detected as being invalid during the presence of said output signal of said engine start detecting means, said fuel injection control means including a housing having a fuel inlet passage, a fuel relief passage and fuel outlet passages connected respectively to cylinders of said engine, a reciprocating shaft defining a compression chamber at one end thereof with an inner wall of said housing and including a spill port, a delivery port and a passage communicating said compression chamber to said fuel relief passage through said spill port and communicating said compression chamber to each of said fuel outlet passages through said delivery port, said compression chamber being arranged to communicate with said fuel inlet passage when said end of the shaft is in a position away from said inner wall and out of communication therewith when said end is in a position proximate to said inner wall, means for causing said shaft to provide both rotary and reciprocating movements with the rotation of an output shaft of said engine, and a solenoid valve responsive to an output signal from said calculating means when said speed indicating signal is detected as being valid for closing and opening said fuel relief passage and forcibly closing said fuel relief passage when said speed indicating signal is detected as being invalid in the presence of the output signal of said engine start detecting means.