 |
Description  |
|
|
BACKGROUND AND SUMMARY OF THE INVENTION
This a application claims the priority of Japanese application No.
8-344933, filed Dec. 25, 1996, the disclosure of which is expressly
incorporated by reference herein.
The present invention relates to a direct injection system internal
combustion engine controlling apparatus, and more particularly, to a fuel
controlling apparatus of a direct injection internal combustion engine and
a fuel controlling apparatus of a vehicle having a direct injection
internal combustion engine. An operation condition of the internal
combustion engine controlling apparatus and the vehicle having the
internal combustion engine is discriminated, and the fuel for the internal
combustion condition engine controlling apparatus and the vehicle is
controlled by accompanying with the above stated discrimination relating
to the operation condition.
A conventional fuel controlling apparatus of a direct injection internal
combustion engine is shown, for example, in Japanese patent laid-open
publication No. Sho 62-191,622 . In this document, the internal combustion
engine comprises a two-layer structure piston and a combustion chamber.
The two-layer structure piston has a shallow plate portion and a depth
plate portion which are provided on an apex portion of the piston.
However, in the above stated conventional direct injection internal
combustion engine technique, to promote a fuel atomization of the internal
combustion engine in which the apex portion of the piston has the
two-layer structure piston, at a high load area the fuel is dividingly
injected during both an intake stroke and a compression strokes, and
further both at a middle load area and at a low load area the fuel is
injected singly during only the compression stroke.
As stated above, in the above conventional fuel controlling apparatus of
the direct injection internal combustion engine technique, at the high
load area the divided fuel injection is carried out during both the intake
stroke and the compression stroke, and at both the middle load area and at
the low load area the single fuel injection is carried out during only the
compression stroke.
However, in the above stated conventional fuel controlling apparatus of the
direct injection internal combustion engine technique, no consideration is
given to a selection of an optimum combustion condition of a
stratification combustion, an intermediate combustion and a homogeneous
combustion according to a combustion stability property of the internal
combustion engine, for example, such a combustion stability property is
determined in accordance with an output condition and an acceleration
condition of the vehicle.
Further, in the above conventional direct injection internal combustion
engine, there is no consideration about an improvement of a smoke property
in which the smokes occurred due to the combustion of the internal
combustion engine can be reduced.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a direct injection
internal combustion engine controlling apparatus wherein, by assuring a
low fuel consumption operation according to an operation under an
extremely lean air-fuel ratio (A/F) condition which is a specific
characteristic of a direct injection internal combustion engine, a
compatibility of important characteristics can be realized with a high
level. The above stated important characteristics are an improvement of a
combustion stability property of the internal combustion engine and an
improvement of a smoke property of the internal combustion engine.
Another object of the present invention is to provide a fuel controlling
apparatus of a direct injection internal combustion engine and a fuel
controlling apparatus of a vehicle having a direct injection internal
combustion engine wherein a combustion stability property of the internal
combustion engine and the vehicle having the internal combustion engine
can be improved.
A further object of the present invention is to provide a fuel controlling
apparatus of a direct injection internal combustion engine and a fuel
controlling apparatus of a vehicle having a direct injection internal
combustion engine wherein smoke produced by combustion in the internal
combustion engine can be reduced remarkably.
According to the present invention, the above stated objects are attained
by selecting a stratification combustion area, a homogeneous combustion
area and an intermediate combustion area in the direct injection internal
combustion engine according to the operation condition. The intermediate
combustion area is formed at an intermediate portion of the above stated
stratification combustion area and the homogeneous combustion area of the
direct injection internal combustion engine.
In the direct injection internal combustion engine controlling apparatus,
as the operation condition discriminating feature for discriminating the
combustion condition of the internal combustion engine, a concentration of
smoke exhausted from the internal combustion engine or a dispersion in the
cylinder every an explosion stroke each of the internal combustion engine
is employed.
In the direct injection internal combustion engine controlling apparatus,
as the operation condition discriminating feature for discriminating the
output condition of the internal combustion engine, a deviation value
between a target torque value and an actual torque value is employed.
In the direct injection system internal combustion engine controlling
apparatus, as a result obtained by the operation condition discriminating
feature for discriminating the operation condition of the internal
combustion engine, using indexes for indicating a stability degree of the
operation condition which comprises a first predetermined value and a
second predetermined value which is larger than the first predetermined
value, when the index for indicating the stability degree of the operation
condition is smaller than the predetermined value, stratification
combustion is made, and when the index for indicating the stability degree
of the operation condition is larger than second predetermined value,
homogenous combustion is made.
In the direct injection internal combustion engine controlling apparatus,
when a judgment result value of the operation condition judgment is more
than a predetermined value, in a transfer of each combustion among
stratification combustion, homogenous combustion or intermediate
combustion, during a predetermined transfer, an allocation rate of the
homogenous combustion and the stratification combustion is changed
gradually.
Namely, the above stated objects can be attained by in a direct injection
internal combustion engine controlling apparatus having things for
controlling a fuel injection amount and a fuel injection timing of fuel
which is supplied to a direct injection internal combustion engine, a
combustion controlling feature for controlling the fuel to a homogenous
combustion area for injecting the fuel in a respective cylinder during an
intake stroke of the internal combustion engine, a stratification
combustion area for injecting the fuel in the respective cylinder during a
compression stroke of the internal combustion engine, and an intermediate
combustion area which is a combustion area between the homogenous
combustion area and the stratification combustion area and for injecting
dividingly the fuel at a predetermined rate during the respective intake
stroke and the respective compression stroke.
The direct injection internal combustion engine controlling apparatus has
further an operation discrimination feature for discriminating an
operation condition in accordance with at least one selected from a
combustion condition of the internal combustion engine, an output
condition of the internal combustion engine and an acceleration condition
of a vehicle, and a selection feature for selecting at least one selected
from homogenous combustion, stratification combustion and intermediate
combustion in accordance with a result of the operation condition
discrimination .
BRIEF DESCRIPTION OF DRAWINGS
Other objects, advantages and novel features of the present invention will
become apparent from the following detailed description of the invention
when considered in conjunction with the accompanying drawings wherein:
FIG. 1 is a schematic view showing one engine system having a direct
injection internal combustion engine controlling apparatus according to
the present invention;
FIG. 2 is a graph showing a characteristic example of a direct injection
internal combustion engine controlling apparatus as seen in FIG. 1;
FIG. 3 is a graph showing a characteristic example of a direct injection
internal combustion engine controlling apparatus;
FIG. 4 is a graph showing a characteristic example of a direct injection
internal combustion engine controlling apparatus;
FIG. 5 is a graph showing a characteristic example of a direct injection
internal combustion engine controlling apparatus;
FIG. 6 is an explanatory chart for explaining the basic performance of a
direct injection internal combustion engine controlling apparatus;
FIG. 7 is a graph for explaining the basic performance of a direct
injection internal combustion engine controlling apparatus;
FIG. 8 is a graph for explaining the basic performance of a direct
injection internal combustion engine controlling apparatus;
FIG. 9 is a graph for explaining the basic performance of a direct
injection internal combustion engine controlling apparatus;
FIG. 10 is an explanatory view showing one embodiment of a direct injection
internal combustion engine controlling apparatus according to the present
invention;
FIG. 11 is an explanatory view showing another embodiment of a direct
injection internal combustion engine controlling apparatus according to
the present invention;
FIG. 12 is an explanatory view showing yet another embodiment of a direct
injection system internal combustion engine controlling apparatus
according to the present invention;
FIG. 13 is an explanatory view showing still another embodiment of a direct
injection internal combustion engine controlling apparatus according to
the present invention;
FIG. 14 is a flow chart showing one embodiment of a direct injection
internal combustion engine controlling apparatus according to the present
invention;
FIG. 15 is a flow chart showing a second embodiment of a direct injection
internal combustion engine controlling apparatus according to the present
invention;
FIG. 16 is a flow chart showing a third embodiment of a direct injection
internal combustion engine controlling apparatus according to the present
invention;
FIG. 17 is a flow chart showing a fourth embodiment of a direct injection
internal combustion engine controlling apparatus according the present
invention;
FIG. 18 is a flow chart showing a fifth embodiment of a direct injection
internal combustion engine controlling apparatus according to the present
invention;
FIG. 19 is a flow chart showing a sixth embodiment of a direct injection
internal combustion engine controlling apparatus according to the present
invention; and
FIG. 20 is a flow chart showing a seventh embodiment of a direct injection
internal combustion engine controlling apparatus according to the present
invention.
DETAILED DESCRIPTION OF THE DRAWINGS
In FIG. 1, air is taken in by an engine 8 from an inlet port of an air
cleaner 1 and passes through a throttle valve body 6 on which a throttle
valve 5 for control an intake air flow amount is provided and then enters
into a collector 7. Herein, the throttle valve 5 is connected to a motor
10 which drives the throttle valve 5, and by driving the motor 10 the
throttle valve 5 is operated and the intake air flow amount in the engine
8 is controlled.
The intake air reaching the collector 7 is distributed to a respective
intake manifold pipe 9 which is connected to a respective cylinder of
engine 8 and the air is introduced into the respective cylinder. In this
intake manifold pipe 9, a SCV (swirl control valve) 31 is provided on the
respective cylinder and in the SCV the intake air is given a deflection
force. In the respective cylinder of the engine 8, the air being given the
deflection force is mixed with an atomized fuel .
From a fuel tank 11 a fuel such as gasoline is sucked and pressurized by a
fuel pump 12, and this fuel is supplied to a fuel system in which a fuel
injector 13, a fuel pressure regulator 14 are arranged. After that, the
fuel is controlled at a predetermined pressure value by the fuel pressure
regulator 14, and the regulated fuel is injected to the respective
cylinder of the engine 8 from the fuel injector 13 which can open at a
fuel injection port to the respective cylinder. Further, from an air flow
meter 3 a signal indicating the intake air flow amount is outputted, and
this signal is inputted into a control unit 15.
Further, a throttle valve sensor 18 is provided on the throttle valve body
6, and this sensor 18 detects an opening degree of the throttle valve 5.
An output of this sensor 18 is also inputted into the control unit 15.
The engine system of the direct injection system internal combustion engine
controlling apparatus according to the present invention comprises an
optical system crank angle sensor 16, and this sensor 16 is driven
rotatively by a cam shaft and outputs a signal indicating a rotational
position of a crank shaft with an accuracy of at least 2-4.degree. degree.
The signal relating to the rotational position of the crank shaft is also
inputted into the control unit 15. Using these various signals, an
injection timing of the fuel and an ignition timing of an ignitor are
controlled.
The above described engine system also comprises an air-fuel ratio sensor
(A/F sensor) 20, this A/F sensor 20 being provided on an exhaust pipe and
detecting and outputting an actual operation air-fuel ratio (A/F)
according to components of the exhaust gas. This signal is also inputted
into the control unit 15 similarly to the above described various other
signals.
As stated above, the control unit 15 in the signals from the various
sensors for detecting the operation condition of the engine 8 and carries
out a predetermined execution processing. As a result of the execution,
the control unit 15 further outputs the executed various control signals
and also output a respective predetermined control signal to the fuel
injector 13, an ignition coil 17 and the motor 10 for operating the
throttle valve 5. The control unit 15 also carries out a fuel supply
control, an ignition timing control, and an intake air flow amount
control.
In the above described engine system, the characteristics of the engine are
shown in FIG. 2 in which the air-fuel ratio (A/F) of a mixture air to be
combusted is set to a lean condition under a stoichiometric air-fuel ratio
((A/F).smallcircle.).
In this example of the direct injection internal combustion engine
controlling apparatus, the engine 8 is operated at the lean condition of
the air-fuel ratio having 25 (A/F=25) under at a constant torque and under
a constant engine rotation number (Ne=1400 rpm). Further, the load
conditionis called a road-load condition. The load conditions shown in
FIG. 3, FIG. 7 and FIG. 8, etc. are the same conditions as shown in FIG.
2, except as noted.
The example of the direct injection internal combustion engine controlling
apparatus in FIG. 2 shows engine performance under homogeneous combustion.
It is understood that in accordance with the injection timing of the fuel,
"CPi" indicating a combustion stability property of the engine is changed.
Further, the engine is affected by an HC property and a smoke property, in
particular since the smoke increases abruptly or the smoke property
becomes bad abruptly when the finish of fuel injection is delayed from
BTDC 60.degree., it is necessary to operate in an area in which the smoke
property is lower than 0.5. This value is an allowance limitation value of
the smoke, in other words a target value of the smoke property is less
than 0.5.
Next, FIG. 3 and FIG. 4 are measurement examples of the engine performances
under a stratification combustion condition of the direct injection
internal combustion engine controlling apparatus. In these figures, by
varying the respective injection timing of the fuel and the ignition
timing of the ignitor, the combustion stability property "CPi" and the
smoke property have been measured. In both FIG. 3 and FIG. 4, a dotted
linear line shows a portion where the fuel injection and the ignition are
carried out at the same time.
At the condition under the air-fuel ratio of 40 (A/F=40), the operation
condition of the engine has a target value of the combustion stability
property "CPi", which is a range of less than 0.5%, and this value of 0.5%
is an allowance limitation value of the combustion stability property
"CPi" also the target value of the smoke property, which is less than 0.5,
can be cleared, (for example a portion of the injection start timing of
50.degree. and the ignition timing of 20.degree.).
However, at the actual operation condition of the engine, the circumstances
shown in FIG. 5 occur. Further, this figure what occurs by keeping both
the rotation speed (Ne) and the intake air amount of the engine 8
constant, the supplied air-fuel ratio is changed from 40 (A/F=40) to 14.7
((A/F).smallcircle.=14.7; .lambda.=1). In this figure, .largecircle. mark
indicates the stratification combustion condition (the compression stroke
fuel injection) and .circle-solid. mark indicates the homogeneous
combustion condition(the intake stroke fuel injection). As a result, as
shown an upper stage in FIG. 5, a need exists to improve the smoke
property.
Firstly, in FIG. 5, with respect to the smoke at an upper stage, the smoke
is substantially zero under homogeneous combustion stratification
combustion during an air-fuel ratio of 20-40 (A/F=20-40) there are
portions in which the value of the smoke property exceeds 0.5.
On the other hand, the "surge torque property" indicating the combustion of
the engine at a lower half in FIG. 5 exceeds a target value of 0.8 kgf-m
under both stratification combustion and homogeneous combustion each
having an air-fuel ratio is in the vicinity of 20 (A/F.apprxeq.20).
As a result, as shown at the lower half in FIG. 5, it is necessary to
improve the surge torque property. The dispersion in the surge torque is
caused by the dispersion of the pressure in the cylinder during every the
explosion stroke.
FIG. 6 provides a summarized conception about the respective
characteristics of the homogeneous combustion condition, the
stratification combustion condition and a weak stratification combustion
condition. The weak stratification combustion condition is intermediate
the homogeneous combustion condition and the stratification combustion
condition. The injection of the fuel under homogeneous combustion is
carried out during the engine intake stroke and the injection of the fuel
under the stratification combustion is carried out during the engine
compression stroke.
Further, the combustion is stable because the engine structure is designed
to obtain the most suitable structure for the stratification combustion,
i.e. at the stratification combustion condition it lowers largely the
target value of the combustion stability property "CPi" of 5%, and then a
stable combustion condition exists. However, at homogeneous combustion ,
the combustion stability property "Cpi" having the value of 10% degree
under the air-fuel ratio A/F of 20-25 (A/F=20-25 exists).
On the other hand, as to the smoke property, under the homogeneous
combustion condition the smoke become substantially zero; however, under
the stratification combustion , it is generally recognized that it is very
difficult to make the smoke zero. Next, as to the reduction of the fuel
consumption which is one object for forming stratification combustion,
under homogeneous combustion it is 200 g/psh at a maximum, whereas under
stratification combustion it can attain 180 g/psh which is substantially
the stoichiometric consumption value.
In FIG. 6, in the right-hand column, weak stratification combustion is
summarized. The weak stratification combustion is an intermediate
combustion method, and this weak stratification combustion is able to
obtain the merits of the both of the homogenous combustion and the
stratification combustion at a maximum.
As shown in the right-hand column in FIG. 6, in accordance with the
employment of weak stratification combustion, then high stability of the
stratification combustion smoke in the homogenous combustion , and further
the low fuel consumption percentage in the homogenous combustion can all
be expected.
In other words, by taken into consideration objects or the results of the
actual facts of the engine structure, and by combining with the above
three combustion methods, i.e. homogenous combustion, stratification
combustion and weak stratification combustion, desirable combustion in the
direct injection internal combustion engine near to the ideal combustion
can be achieved.
FIG. 7 and FIG.of the weak stratification combustion which is the
intermediate combustion area. FIG. 7 is the measurement result of the
air-fuel ratio of 20 (A/F=20) and FIG. 8 is the measurement result of the
air-fuel ratio of 25 (A/F=25). In these figures, the compression stroke
fuel injection rate, namely a rate of the stratification combustion area,
is indicated at the horizontal axis shows and the data concerning the
combustion stability property (CPi) and the smoke property are shown on
the vertical axis.
In FIG. 8, two measurement results of the combustion stability properties
indicated by curve lines of CPi(1) and CPi(2) and two measurement results
about the smoke properties indicated by curve lines SMOKE(1) and SMOKE(2)
are shown in a lower diagram. Further, two measurement results about HC
properties indicated by curve lines of HC(1) and HC(2) and two measurement
results about NOx properties indicated by curve lines NOx(1) and NOx(2)
are shown in the middle diagram.
As understood from FIG. 7 and FIG. 8, the combustion stability property
(CPi) does not chance very much (the combustion stability property (CPi)
hardly changes); however, the smoke property has a tendency to increase
more when the rate of the stratification combustion becomes higher.
Accordingly, by controlling the rate between the stratification combustion
and the homogeneous combustion the combustion performance near the ideal
combustion can be obtained.
In other words, during one combustion cycle, the fuel is dividingly
infected two times during the intake stroke and during the compression
stoke or the fuel is dividingly injected during the intake stroke and the
fuel is dividingly infected during the compression stoke, respectively and
further the rate between the stratification combustion and the homogeneous
combustion is varied, such that the combustion performance near the ideal
can be obtained.
FIG. 9 shows a measurement result of the engine performance at a condition
the air-fuel ratio of 20 (A/F=20) at the constant rotation number (Ne=1400
rpm ) according to the injection timing by varying the rate between the
stratification combustion and the homogeneous combustion. As shown at a
right upper portion in FIG. 9, the rate between the stratification
combustion and the homogeneous combustion is varied with six rates in this
example.
It can be confirmed that when the fuel rate between the stratification
combustion and homogeneous combustion is changed, the combustion stability
property (Cpi), the HC property, and the smoke property are changed.
Hereinafter, other embodiments of the direct injection internal combustion
engine controlling apparatus according to the present invention will be
explained.
FIG. 10 shows a setting map of the air-fuel ratio (A/F) of the direct
injection system internal combustion engine with respect to the engine
rotation number (Ne) and the engine output. The stratification combustion
area covers low rotation number and the low load, and on the other hand,
the homogenous combustion area covers high load. Between the
stratification combustion area and the homogenous combustion area, there
is the intermediate combustion area (the weak stratification combustion
area).
In FIG. 11, the vehicle speed is indicated on the horizontal axis and the
air-fuel ratio (A/F) is indicated on the vertical axis, to clearly make a
control image for the direct injection internal combustion engine. As
shown in FIG. 11, to perform a control for the direct injection internal
combustion engine, there are three combustion areas, namely the
stratification combustion area, the homogenous combustion area, and the
intermediate combustion area (the weak stratification combustion area) in
accordance with the size of the air-fuel ratio (A/F) and the vehicle
speed.
In FIG. 12, the various combustion areas are shown on the horizontal axis
and the combustion stability property (CPi) and the smoke property are
shown on the vertical axis. Using this figure, the characteristics of
three combustion areas are shown in accordance with the combustion
stability property (CPi) and the smoke property and further this figure is
arranged to demonstrate the characteristics of each combustion condition
which have been explained in FIG. 6.
In FIG. 13, the swirl strength in the cylinder of the engine is shown on
the horizontal axis and the property are shown on the vertical axis. Using
this figure, the swirl control valve (SCV) 31 in FIG. 1 will now be
explained .
In the stratification combustion area, to improve the robust property of
the combustion, it is generally desirable to increase the gas fluidity
(the strength of the swirl) in the cylinder of the engine. Further, during
the homogeneous combustion, to obtain the stable combustion, the gas
fluidity is considered a very important factor. As a result, the control
of the size of the gas fluidity is an important factor in the success or
failure for the fuel control of the direct injection internal combustion
engine.
Hereinafter, various embodiments of the control of the size of the gas
fluidity in the direct injection internal combustion engine according to
the present invention will be explained.
FIG. 14 is a control flow chart showing a basic conception of a selection
of the stratification combustion area, the homogeneous combustion area and
the intermediate combustion area. In step 141, the combustion stability
property of the engine is detected through a change in the rotation speed
of the engine and a fluctuation in the engine combustion pressure etc.
In step 142, the existence of the combustion stability property within a
standard value range is judged , and according to the circumstances the
combustion stability property is determined. Namely, when the surge
torque, etc. which are the indexes of the combustion stability property is
larger than the standard value range, the stability of the engine
combustion is regarded as important, and then the combustion stability
property is moved to the stratification combustion area.
On the other hand, when the value of the surge torque, etc. which are the
indexes of the combustion stability property is smaller than the standard
value range, then the combustion stability property is moved to the
homogeneous combustion area. Further, when the combustion stability
property is within the standard value range, such circumstances are
continued, i.e., the former circumstances are maintained.
In FIG. 14, the combustion stability property of the engine is regarded the
judgment standard. On the other hand, FIG. 15 is a control flow chart
showing the basic conception of the selection of the stratification
combustion area, the homogeneous combustion area and the intermediate
combustion area by paying attention to the smoke property.
The smoke generated from the engine directly detected through a sensor (for
example, a combustion optical sensor, etc.); however, by detecting the
change of the engine speed and the fluctuation in the engine combustion
pressure, etc. estimate or judge in accordance with the factors which
relate to a deterioration of the combustion condition (step 151).
In step 152 shown in FIG. 15, the existence of a smoke level within a
standard value range is judged , and according to the circumstances when
the smoke level is larger than the standard value range, the smoke
property is regarded as important than the engine combustion property, and
then the smoke property is moved to the homogeneous combustion area.
On the other hand, when the smoke property is smaller than the standard
value range, then the smoke property is moved to the stratification
combustion area. Further, when the smoke property is within the standard
value range, such circumstances are continued, i.e., the former
circumstances are maintained.
FIG. 16 is a control flow chart in which both the engine combustion
stability property and the smoke property become the judgment standards.
Attention is paid to the fact that an area regarded as important for the
engine combustion stability property differs from as area regarded as
important for the smoke property. When there is no problem with the
combustion stability property, the homogeneous combustion can be selected
as shown in step 169.
On the other hand, when there is a problem with the combustion stability
property (step 165), the stratification combustionis selected; however, in
this case a required value of the smoke property is judged from the
operation condition (step 166) and an allowable tolerance range is
estimated.
When the smoke property are regarded as important , in a such case the
stratification combustion area is employed as shown in step 171, but
otherwise the intermediate combustion area (this is the two times
injection control area as stated above) is employed as shown in step 170.
FIG. 17 shows a control flow chart where the combustion stability property
is solved according to the strength of the gas fluidity which gives an
affect to the cylinder of the engine. In other words, when there is bad
combustion stability property (step 173), the swirl strength is increased
and the combustion is stabilized.
When the combustion stability property, namely the surge torque etc. for
indicating combustion stability , is small or within the standard value
range and there is no problem with the stability of the combustion (step
174; step 175), the importance about the smoke property is judged and when
the smoke property is not important (step 177), the swirl strength is
increased.
On the other hand, when the importance about the smoke property is judged
as important, with the circumstances near to homogeneous combustion than
to intermediate combustion, the control where the swirl strength is small
is selected.
Each of FIG. 18, FIG. 19 and FIG. 20 shows a flow chart concerning the
combustion control of the direct injection internal combustion engine in a
case where the operation condition of the engine is in a transient
condition.
Now, in the flow chart shown in FIG. 18, at the acceleration judgment step
18C, when the acceleration judgment is larger than a predetermined value
and then the homogeneous combustion is selected, in step 18D the time
constant is set to one (1) so as to carry out the change-over from the
stratification combustion which is the present combustion condition to the
homogeneous combustion.
On the other hand, in step 18E, the time constant is set to two (2) so as
to carry out the change-over from the stratification combustion which is
the present combustion condition to the intermediate combustion.
As stated above, by setting suitably the value of the time constant, since
it can change over by waiting for the change of the intake air flow
amount, the torque stepwise difference which is generated due to the
combustion condition change-over can be eliminated to counteract shock .
FIG. 19 is a flow chart showing a method for smoothing the operation
property by improving further the stepwise change-over combustion
condition. In other words, when during the acceleration time the
stratification combustion is changed over to the homogenous combustion, as
shown in step 19K, each time the control routine runs, a rate of the
stratification combustion and a rate of the homogeneous combustion are
varied with a function (f) and then the combustion condition is changed
over.
The above stated function (f) is a factor which can be freely selected, for
example, according to the operation condition, the size of the
acceleration and the engine operation condition, etc.In accordance with
the employment of this control method shown in FIG. 19 the intermediate
combustion area can be gradually obtained.
Further, FIG. 20 is a flow chart showing a control method in a case where
taking the vehicle condition into account as the operation property is
regarded as important . As a key factor for securing the operation
property, "a target engine torque" is determined in accordance with the
engine rotation number, and the acceleration pedal step-in amount and then
the acceleration judgment is carried out (step 20C).
As a result, the change-over among the stratification combustion, the
homogenous combustion and the intermediate combustion is carried out, and
alone therewith the respective combustion allocation is satisfied to the
target engine torque . At the same time the combustion stability property
can be selectively and optimally controlled.
Herein, when the acceleration judgment is small and as shown in a step 20F
there is the stratification combustion, as shown in step 20M in accordance
with a difference between the target torque and the actual torque, the
method transfers to the homogenous combustion or to the intermediate
combustion. As a result, the direct injection internal combustion engine
achieves the objects of optimized operation property, fuel consumption and
exhaust gas purification.
According to the present invention, with the improvement in the operation
property, therefore it is possible to draw out improved performance of the
direct injection internal combustion engine.
The foregoing disclosure has been set forth merely to illustrate the
invention and is not intended to be limiting. Since modifications of the
disclosed embodiments incorporating the spirit and substance of the
invention may occur to persons skilled in the ar | | |
