Internal-combustion engines – Combustion chamber means having fuel injection only – Combustible mixture stratification means
Reexamination Certificate
1999-12-02
2001-05-01
Yuen, Henry O. (Department: 3747)
Internal-combustion engines
Combustion chamber means having fuel injection only
Combustible mixture stratification means
C303S114300
Reexamination Certificate
active
06223716
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a fuel control system for a cylinder injection type internal combustion engine (also known as the direct fuel injection type engine) for a motor vehicle in which fuel is injected directly into engine cylinders to control engine output torque. More particularly, the present invention is concerned with a fuel control system for the cylinder injection type internal combustion engine which system is so designed as to ensure brake operating pressure while protecting positively combustion performance or combustibility of the engine against degradation.
2. Description of Related Art
In general, in the internal combustion engine employed as the automobile engine or the like, an injector for fuel injection is installed within an intake manifold of an intake pipe of the engine so that the fuel as injected can be charged into engine cylinders together with the intake air.
For having better understanding of the principle underlying the invention, technical background thereof will be described in some detail.
FIG. 10
is a schematic diagram showing a conventional fuel control system for an internal combustion engine in which a fuel injector is disposed within an intake pipe.
Referring to
FIG. 10
, an engine
1
constituting a main body of the internal combustion engine system includes a plurality of cylinders. However, for simplification of the illustration, only one of the cylinders is representatively shown in FIG.
10
.
An intake pipe
1
a
is communicated to an exhaust pipe
1
b
through combustion chambers of the engine
1
to which a crank shaft
1
c
is coupled at one end thereof.
The intake pipe or manifold
1
a
serves for charging a mixture of intake air and fuel (hereinafter also referred to as the air-fuel mixture) into the engine
1
, while the exhaust pipe
1
b
is used for discharging the exhaust gas resulting from the combustion of the air-fuel mixture within the engine
1
. The crank shaft
1
c
is driven rotationally by the engine
1
. Cooling water
1
d
forced to flow around the engine
1
serves for cooling the engine
1
.
An air flow sensor
2
installed at an inlet port of the intake pipe
1
a
measures intake air quantity Qa as the information concerning the air flow rate or amount of air supplied to the engine
1
. Furthermore, mounted within the intake pipe
1
a
is a throttle valve
3
which is operatively coupled to an accelerator pedal (not shown) operated by a driver of the motor vehicle for regulating the intake air quantity Qa in dependence on the magnitude of depression stroke of the accelerator pedal.
For the purpose of detecting angular position of the throttle valve
3
, i.e., throttle opening degree &thgr; of the throttle valve
3
, a throttle position sensor
4
is provided in association with the throttle valve
3
.
Further provided in association with the crank shaft
1
c
is a crank angle sensor
5
which is designed for detecting rotation speed (rpm) of the crank shaft
1
c
to thereby output a pulse signal in synchronism with the rotation of the crank shaft
1
c
. This signal will be referred to as the crank angle signal SGT. Thus, the crank angle signal SGT carries the information concerning the rotation speed (rpm) of the engine
1
as well as the information concerning the angular position of the crank shaft
1
c
(i.e., crank angle).
Temperature Tw of the cooling water
1
d
is detected by a water temperature sensor
6
which thus can serve as a means for detecting a warmed-up state of the engine
1
.
An O
2
-sensor
7
provided in association with the exhaust pipe
1
b
is designed to detect an oxygen concentration Do of the exhaust gas discharged from the engine
1
to the exhaust pipe
1
b.
For the purpose of controlling operations of the internal combustion engine system described above, a control unit
8
is provided, which may be implemented in the form of a microprocessor or microcomputer. The detection signals Qa, &thgr;, SGT, Tw and Do outputted from the various sensors
2
,
4
,
5
,
6
and
7
installed at the peripheral portions of the engine
1
, as mentioned above, are supplied as input information signals to the control unit
8
which in turn outputs driving control signals for various devices and actuators such as spark plugs and fuel injectors (described hereinafter) in dependence on the operation states of the engine to thereby perform various sequential controls inclusive of the ignition timing control and fuel injection control for each of the cylinders of the engine
1
. Owing to such arrangement as mentioned above, the engine
1
can be driven through combustion of the air-fuel mixture at the desired ignition timing with the desired air-fuel ratio.
A spark plug
9
is mounted within each of the cylinders of the engine
1
, being exposed to the combustion chamber defined within the cylinder, wherein the firing of the spark plug
9
is controlled by an ignition timing control signal P outputted from the control unit
8
.
As can be seen in
FIG. 10
, a bypass passage BP is provided in parallel to the intake pipe
1
a
so that the intake air can controllably bypass the throttle valve
3
.
More specifically, operation of the air bypass valve
10
provided at the bypass passage BP is controlled by a bypass control signal B outputted from the control unit
8
, whereby the rate of bypass air flow (i.e., bypassed intake air quantity) Qb which bypasses the throttle valve
3
can be regulated by selectively opening or closing the bypass passage BP. In this manner, there can be realized not only the engine torque control in the running state of the motor vehicle but also the engine rotation speed control in the idling operation state of the engine (the engine operation state in which the throttle valve
3
is fully closed).
Referring continuously to
FIG. 10
, a fuel injector
11
is mounted within the intake manifold located downstream of the intake pipe
1
a
. Operation of the fuel injector
11
is controlled by the fuel injection control signal J outputted from the control unit
8
, whereby controlled quantity of the fuel is supplied to the engine cylinders.
An exhaust gas recirculation pipe (hereinafter also referred to as the EGR pipe) EP through which the exhaust pipe
1
b
is communicated with the intake pipe
1
a
serves for recirculating the exhaust gas discharged from the engine
1
into the combustion chamber thereof with a view to reducing harmful components of the exhaust gas such as nitrogen oxides or NO
x
by burning again the exhaust gas.
An exhaust gas recirculation valve
12
(hereinafter also referred to as the EGR valve) mounted on the EGR pipe EP is driven by an EGR control signal E issued from the control unit
8
to thereby control the amount or quantity of the exhaust gas (referred to as the EGR quantity in short) recirculated from the exhaust pipe
1
b
to the intake pipe
1
a.
A cylinder identifying sensor
13
mounted on the cam shaft of the engine
1
outputs to the control unit
8
a cylinder identifying signal SGC for identifying the combustion cylinder in synchronism with the operation of the intake valve of the engine
1
.
A check valve
15
communicated to the intake manifold of the intake pipe
1
a
serves to hold a lower limit value of an intake or manifold pressure (negative pressure or vacuum) Pi within the intake pipe
1
a
as a brake operating pressure PB.
Communicated to the check valve
15
is a master bag
16
which serves for storing the brake operating pressure PB in a predetermined negative pressure state or at a predetermined vacuum level)
The check valve
15
and the master bag
16
cooperate to constitute a brake operating pressure generating means which may also be referred to as the brake pressure multiplication mechanism for generating a negative brake operating pressure PB on the basis of the intake pressure (intake-manifold pressure) Pi of the engine
1
. By using the brake operating pressure PB as a driving energy source, a braking mechanism (not shown) is actuated for assisting
Gimie Mahmoud M
Mitsubishi Denki & Kabushiki Kaisha
Sughrue Mion Zinn Macpeak & Seas, PLLC
Yuen Henry O.
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