Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
2000-04-19
2001-01-09
Kwon, John (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S478000
Reexamination Certificate
active
06170468
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fuel injection control system for an internal combustion engine, which system is designed for performing a simultaneous fuel injection upon starting operation of the engine. More particularly, the present invention is concerned with a fuel injection control system for an internal combustion engine for ensuring a fuel quantity demanded for the simultaneous fuel injection while improving ignitability in the engine operation starting phase.
2. Description of Related Art
Heretofore, in the field of the internal combustion engines for motor vehicles such a fuel injection control system is known which is designed for performing a simultaneous fuel injection for a plurality of cylinders in every ignition cycle in an engine operation starting phase in which a battery voltage is likely to change remarkably with a view to enhancing the ignitability by stabilizing the fuel injection quantity.
For having better understanding of the invention, background techniques thereof will first be described in some detail.
FIG. 7
is a functional block diagram showing schematically a hitherto known or conventional fuel injection control system for an internal combustion engine (hereinafter also referred to simply as the engine) which is presumed to be a three-cylinder engine, only by way of example.
FIG. 8
is a timing chart for illustrating injector control operation performed by the conventional fuel injection control system in the engine operation starting phase (i.e., simultaneous fuel injection phase).
Referring to
FIG. 8
, a crank angle signal SGT carries a train of pulses each having a leading or rising edge and a trailing or falling edge indicative of reference positions (B75° and B5°), respectively, for each of cylinders #
1
to #
3
.
Parenthetically, the reference position B75° represents a position preceding by 75° in terms of the crank angle or CA relative to the top dead center (TDC) in the compression stroke of each cylinder, while the reference position B5° represents a position preceding by 5° CA to the top dead center.
As is well known in the art, the reference position B75° (leading or rising edge) is used as the reference position for the ordinary timer control performed on a cylinder-by-cylinder basis while the reference position B5° (falling edge) is employed for setting the initial ignition timing on a cylinder-by-cylinder basis in the engine operation starting phase.
Further, fuel injection signals J
1
, J
2
and J
3
for the individual engine cylinders (#
1
, #
2
and #
3
) are illustrated in
FIG. 8
in combination with operation of an engine starting switch, a crank angle signal SGT and strokes (suction, compression, explosion, and exhaust strokes) of the individual cylinders.
Referring to
FIG. 7
, a crank angle sensor
1
is installed in association with the crank shaft of the engine (not shown) and designed to generate the crank angle signal SGT carrying a train of pulses which represent the reference positions (B75°, B5°) for the individual cylinders (cylinder #
1
to cylinder #
3
), respectively, in dependence on the rotational positions of the engine, as can be seen in FIG.
8
.
A variety of sensors denoted generally and collectively by reference numeral
2
represent a water temperature sensor for detecting, for example, a temperature of cooling water as the temperature information of the engine in addition to a throttle opening sensor, an intake air flow sensor, an engine speed sensor, a starting switch sensor and the like, as is well known in the art. These sensors serve for generating a variety of information indicating operating states of the engine. Of course, the crank angle sensor
1
can also serve as the engine speed sensor as well and may thus be considered as one of the various sensors
2
.
An electronic control unit (ECU)
3
which may be constituted by a microcomputer or microprocessor is so designed as to generate an ignition signal P and a fuel injection signal J for controlling the engine operation on the basis of the crank angle signal SGT derived from the output of the crank angle sensor
1
and the engine operating state information derived from the outputs of the various sensors
2
.
An ignition system
4
is comprised of a power transistor (not shown), an ignition coil (not shown) and spark plugs (not shown either) and driven in response to the ignition signal P generated in synchronism with the crank angle signal SGT. The power transistor incorporated in the ignition system
4
is turned on and off in response to the ignition signal P. On the other hand, the ignition coil responds to the on/off operations of the power transistor by generating a high voltage for bringing about electric discharge at the spark plugs for driving the engine.
Each of the fuel injectors
5
is actuated in response to the fuel injection signal J (see
FIG. 8
) having a pulse width or duration substantially proportional to the engine load for injecting a predetermined amount or quantity of fuel into the-associated one of the cylinders of the engine. A basic pulse width or duration Tb of the fuel injection signal J corresponds to the fuel injection time duration of the injector and a sum of the fuel injection quantities in each ignition cycle represents the demanded fuel quantity mentioned previously.
The electronic control unit (ECU)
3
is comprised of a cylinder identifying means
31
for generating a cylinder identifying signal A, an ignition control means
32
for generating the ignition signal P and a fuel injection control means
33
for generating the fuel injection signal J.
The cylinder identifying means
31
incorporated in the electronic control unit
3
is designed to identify each of the engine cylinders on the basis of the crank angle signal SGT to thereby generate the cylinder identifying signal A.
On the other hand, the ignition control means
32
and the fuel injection control means
33
are designed to generate the ignition signal P and the fuel injection signal J, respectively, on the basis of the crank angle signal SGT, the engine operating states represented by the various sensor signals and the cylinder identifying signal A.
For realizing the simultaneous fuel injection in the engine operation starting phase, the fuel injection control means
33
is designed to generate the fuel injection signals J simultaneously for the individual cylinders after the cylinder identification, i.e., after generation of the cylinder identifying signal A.
In that case, the basic fuel quantity Fb per injection for each of the cylinders is set in dependence on the demanded fuel quantity Fs mentioned previously and the number N of the cylinders in accordance with expression (1):
Fb=Fs/N
(1)
Thus, the driving time duration (i.e., the basic pulse width or duration Tb) of the fuel injector
5
for each cylinder is so set that the condition given by above expression (1) can be satisfied. Obviously, in the case of the three-cylinder engine, the basic fuel quantity Fb per injection is one third of the demanded fuel quantity Fs.
At this juncture, it should be mentioned that the cylinder identifying means
31
, the ignition control means
32
and the fuel injection control means
33
incorporated in the electronic control unit
3
may be implemented as a program or programs which can be executed by a microcomputer or microprocessor constituting a main part of the electronic control unit
3
.
Next, referring to
FIG. 8
, description will be made in concrete of the operation of the conventional fuel injection control system for the internal combustion engine shown in FIG.
7
.
At first, when the operator or driver closes the starting switch, the engine is forced to rotate by a starter motor (not shown). The crank angle sensor
1
produces the crank angle signal SGT in synchronism with the engine rotation, which signal SGT is then inputted to the electronic control unit (ECU)
3
.
Since the pulse width of the crank angle signal SGT is offset only
Kwon John
Mitsubishi Denki & Kabushiki Kaisha
Sughrue Mion Zinn Macpeak & Seas, PLLC
LandOfFree
Fuel injection control system for internal combustion engine does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fuel injection control system for internal combustion engine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fuel injection control system for internal combustion engine will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2469587