FIELD OF THE INVENTION
[0001] The present invention relates to a control device of an internal combustion engine
intake throttle valve according claim 1 which keeps the engine stable after the engine
starts.
BACKGROUND OF THE INVENTION
[0002] One example of a control device for controlling an internal combustion engine is
disclosed in Japanese Patent No. 2519120. This conventional control device controls
an intake throttle valve of a diesel engine, one type of the internal combustion engine.
The control device controls the throttle angle of the intake throttle valve of the
diesel engine on the basis of atmospheric pressure, intake air temperature, and coolant
temperature of the diesel engine, etc. For example, the lower the coolant temperature,
the higher the throttle angle of the intake throttle valve is. Then, even during a
control in idling condition of the engine, the throttle angle is set to be higher
if the coolant temperature is low.
[0003] Just after the engine starts, however, a combustion condition in a combustion chamber
of the diesel engine changes swiftly, because a temperature of the combustion chamber
increases swiftly. On the contrary, the coolant temperature changes slowly. Therefore,
when the engine starts, it is impossible to optimize the combustion condition of the
combustion chamber by the controlling method of the conventional control device, because
the throttle angle of the intake throttle valve of the engine is controlled on the
basis of the coolant temperature which changes slowly.
SUMMARY OF THE INVENTION
[0004] It is thus an object of the present invention to solve the aforementioned problem
and to provide a control device of an engine intake throttle valve in which a combustion
condition in a combustion chamber of an internal combustion engine can be optimized
when the internal combustion engine starts.
[0005] To achieve the aforementioned object, a control device of an engine intake throttle
valve according to claim 1 is provided. Preferred embodiments thereof are set forth
in the dependent claims.
[0006] In accordance with one aspect of the invention, a control device for controlling
an intake throttle valve in an intake air flow passage to a combustion chamber in
an internal combustion engine, comprises a combustion chamber temperature estimation
means for estimating a temperature of a combustion chamber in said internal combustion
engine, and a control means for setting a throttle angle of said intake throttle valve
on the basis of the temperature of the combustion chamber detected by said combustion
chamber temperature estimation means after said internal combustion engine starts.
[0007] In the control device, the combustion chamber temperature estimation means may comprise
a temperature detection means for detecting a coolant temperature of the internal
combustion engine, and a time measuring means for measuring an elapsed time after
the internal combustion engine starts, the control means may set the throttle angle
of the intake throttle valve on the basis of the coolant temperature detected by the
temperature detection means and the elapsed time measured by the time measuring means.
[0008] In this control device, when the engine starts, the throttle angle of the intake
throttle valve is controlled by considering not only the coolant temperature of the
internal combustion engine, but also the elapsed time after starting the engine, Consequently,
although the coolant temperature substantially does not change, the combustion condition
of the combustion chamber can be optimized by controlling the throttle angle of the
intake throttle valve responsive to the elapsed time after starting the engine.
[0009] In this control device, the shorter the elapsed time measured by the time measuring
means becomes, the higher the throttle angle of the intake throttle valve is set.
[0010] If the combustion chamber temperature increases swiftly after the internal combustion
engine starts, a combustion condition of the combustion chamber can be optimized by
controlling the throttle angle of the intake throttle valve in such a way that the
shorter the elapsed time, the higher the throttle angle of the throttle intake valve
is.
[0011] In addition to the above-mentioned, the lower the coolant temperature detected by
the temperature detection means becomes, the higher the throttle angle of the intake
throttle valve is set.
[0012] To determine the throttle angle of the intake throttle valve, this device considers
not only the elapsed time after starting the internal combustion engine, but also
the detected coolant temperature. That is, the lower the coolant temperature, the
higher the throttle angle is. Therefore, a more stable combustion condition of the
combustion chamber can be achieved. The throttle angle of the intake throttle valve
can be kept constant only until a predetermined time elapses after starting the engine.
By this method, a stable combustion condition is realized.
[0013] In this control device, the throttle angle of the intake throttle valve may be kept
constant only for a predetermined time after the internal combustion engine starts.
[0014] In this control device, the control means may set a fuel injection timing of the
internal combustion engine on the basis of the coolant temperature detected by the
temperature detection means and the elapsed time measured by the time measuring means.
[0015] In this control device, the shorter the elapsed time measured by the time measuring
means becomes, the more the fuel injection timing is advanced.
[0016] In this control device, the lower the coolant temperature detected by the temperature
detection means becomes, the more the fuel timing is advanced.
[0017] Furthermore, the shorter the elapsed time measured by the time measuring means becomes,
the higher the throttle angle of the intake throttle valve may be set.
[0018] Furthermore, the lower the coolant temperature detected by the temperature detection
means becomes, the higher the throttle angle of the intake throttle valve may be set.
[0019] Furthermore, the fuel injection timing is kept constant after the elapse of the predetermined
time subsequent to the start of the internal combustion engine.
[0020] In the control device of the invention, the internal combustion engine may be a diesel
engine.
[0021] This summary of the invention does not necessarily describe all necessary features
so that the invention may also reside in a sub-combination of these described features.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The above and other objects, features, advantages and technical and industrial significance
of this invention will be better understood by reading the following detailed description
of a presently preferred embodiment of the invention, when considered in connection
with the accompanying drawing, in which:
Fig. 1 is a schematic illustration of the overall structure of a control device which
is installed, for example, on a diesel engine according to one embodiment of the present
invention;
Fig. 2 is a block diagram showing an ECU and input/output signal for the control device
of Fig. 1;
Fig. 3 is a flowchart illustrating a target throttle angle setting routine according
to the first embodiment of the present invention;
Fig. 4 is a data table showing base throttle angles applied to the first embodiment;
Fig. 5 is a data table showing correction factors of coolant temperatures applied
to the first embodiment;
Fig. 6 is a data table showing stabilization times after starting the engine applied
to the first embodiment;
Fig. 7 is a graph showing the relationship between a correction factor and an elapsed
time after starting the engine applied to a modified embodiment;
Fig. 8 is a flowchart illustrating a target fuel injection timing setting routine
according to another embodiment of the present invention;
Fig. 9 is a data table showing base fuel injection timing applied to flowchart in
Fig. 8;
Fig. 10 is a data table showing correction factors of the fuel injection timing by
coolant temperatures applied to the flowchart in Fig. 8;
Fig. 11 is a graph showing the relationship between the target fuel injection timing
and the elapsed time after starting the engine.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] In the following and the accompanying drawings, the present invention will be described
in more detail in terms of the embodiments. A gasoline engine, a diesel engine, etc.
are internal combustion engines. Generally, the present invention is applied to an
internal combustion engine, but some part of this invention concerning a fuel injection
timing control (later described in detail) particularly relates to a diesel engine.
For the convenience of explanation, here a diesel engine is discussed in this embodiment.
[0024] First, FIG. 1 shows the schematic illustration of the overall structure of the control
device of an engine intake throttle valve which is installed on a diesel engine according
to one embodiment of the present invention. As mentioned above, unless specifically
noted, the present invention is not limited to a diesel engine, but applies to all
internal combustion engines.
[0025] A diesel engine (hereinafter called engine) 11 has a plurality of cylinders which
include combustion chambers 12. In an intake stroke of the engine 11, an intake valve
14 responsive to each combustion chamber 12 intakes ambient air through an intake
passage 16 into the combustion chamber 12 by opening an intake port 13. A fuel injection
pump 18 pumps fuel and sends the pressured fuel to a fuel injection nozzle 17 through
a fuel line 19. The fuel injection nozzle 17 injects the fuel into the combustion
chamber 12. In an exhaust stroke of the engine 11, an exhaust valve 23 responsive
to each combustion chamber 12 exhausts exhaust gas through an exhaust passage 24 by
opening an exhaust port 22.
[0026] A step motor 26 drives an intake throttle valve 25 on the basis of a control signal
from an electronic control unit (hereinafter called ECU) 39 so that a throttle angle
of the intake throttle valve 25 is at a desired value. A throttle sensor 58 detects
the throttle angle of the intake throttle valve 25.
[0027] An exhaust gas recirculation (hereinafter called EGR) system 40 recirculates part
of the exhaust gas exhausted from the combustion chamber 12 to the exhaust passage
24 and returns the exhaust gas to the combustion chamber 12. The EGR system 40 provides
an EGR valve 42. The EGR valve 42 regulates the quantity of the exhausted gas which
flows through an EGR passage 41 from the exhaust passage 24 to the intake passage
16.
[0028] The EGR valve 42 has a diaphragm which opens or closes the EGR passage 41 by applying
vacuum or atmospheric pressure. The EGR system 40 provides an electric vacuum regulating
valve (hereinafter called EVRV) 48 which regulates vacuum and atmospheric pressure
introduced into a pressure chamber 46. The EVRV 48 connects a vacuum pump 32 through
a vacuum port 51 and atmosphere through an atmosphere port 53, and regulates vacuum
pressure supplied to the pressure chamber 46. The ECU 39 controls the EVRV 48 by controlling
the electric current. The ECU 39 regulates the EGR valve 42 by controlling the EVRV
48 in response to an operating condition of the engine 11. Therefore, it regulates
the quantity of the EGR.
[0029] A crankshaft 21 of the engine 11 rotates a drive shaft 29 of the fuel injection pump
18. A revolution speed sensor 56 attached to the fuel injection pump 18 detects the
revolution speed of the drive shaft 29. Therefore it detects the revolution speed
of the crankshaft 21, i.e., engine revolutions NE. Furthermore, the revolution speed
sensor 56 detects a rotation position of the crankshaft 21.
[0030] A coolant temperature sensor 57 attached on the engine 11 detects a coolant temperature
THW of the coolant which cools the engine 11, and it outputs an electric signal responding
to the coolant temperature THW to the ECU 39. An intake pressure sensor 59 deposited
in the intake passage 16 detects intake pressure PM in the intake passage 16, and
an electric signal responding to the intake pressure PM to the ECU 39. An accelerator
sensor 61 is positioned close to an accelerator pedal 60, and it outputs an electric
signal showing an acceleration stroke ACCP responding to stroke of the accelerator
pedal 60.
[0031] Fig. 2 shows a block diagram of the ECU 39 and input/output signal for the control
device of Fig. 1. Generally, the ECU 39 includes a central processing unit (i.e. CPU)
63, a read only memory (i.e. ROM) 64, a random access memory (i.e. RAM) 65, a backup
random access memory (i.e. backup RAM) 66, an input port 67, an output port 68, an
inner bus 69, a plurality of buffers 70, a multiplexer 71, A/D converter 72, a wave-shaping
circuit 73, and a couple of drive circuits 74. Electric signals outputted from the
respective sensors 57, 58, 59, and 61 are converted from analog signals to digital
signals by the A/D converter through buffers 70 and the multiplexer 71, and the digital
signals are sent to the input port 67. An electric signal from the revolution speed
sensor 56 is corrected by the wave-shaping circuit 73 and sent to the input port 67.
Electric signals for driving the step motor 26 and the EVRV 48 are given to the respective
drive circuits 74 through the output port 68. After amplifying the electric signals,
the respective drive circuits 74 output them to the step motor 26 and the EVRV 48.
The input port 67 and the output port 68 are connected to the CPU 63, the ROM 64,
the RAM 65, and the backup RAM 66 through the inner bus 69. For example, a control
program housed in the ROM 64 calculates parameters. These parameters are indicated
by the electric signals inputted to the ECU 39. The control program, thus, executes
the control of the intake throttle valve and the EGR.
[0032] In this system of the embodiment, the ECU 39 calculates an amount of fuel injection
QFiN on the basis of the engine revolutions NE detected by the revolution speed sensor
56, the acceleration stroke ACCP detected by the accelerator sensor 61, and the intake
pressure PM detected by the intake pressure sensor 59. Furthermore, the ECU 39 calculates
the target throttle angle LSTRG from the amount of fuel injection QFiN and the engine
revolutions NE. The ECU 39 controls the step motor 26 and sets the actual throttle
angle of the intake throttle valve 25 detected by the throttle sensor 58, so that
the actual throttle angle reaches the target throttle angle LSTRG.
[0033] In this embodiment, the routine shown in the flowchart in Fig. 3 is executed once
per e.g. 8 milli-seconds. At each time of the routine processing, the target throttle
angle LSTRG is set. When the engine starts in a cooled condition, here, the throttle
angle of the intake throttle valve 25 is controlled in response to swift rising of
the temperature of the combustion chamber 12, and the combustion condition of the
combustion chamber 12 is optimized.
[0034] Next, referring to the flowchart shown in Fig. 3, a process for setting the target
throttle angle in this embodiment is described in details as follows.
[0035] By referring to a data table showing base throttle angles in Fig. 4, a base throttle
angle LSBSE responsive to the engine revolutions NE and an amount of fuel injection
QFiN is given (step S101).
[0036] In the data table showing base throttle angles 111, the vertical line shows the amount
of fuel injection QFiN and the horizontal line shows the engine revolutions NE. The
base throttle angle LSBSE is given as an integral in the range from 0 to 179. The
larger the amount of fuel injection QfiN, the closer to 0 the base throttle angle
LSBSE (i.e. higher angle) becomes. Furthermore, the lower the engine revolutions NE,
the closer to 179 the base throttle angle LSBSE (i.e. lower angle) becomes.
[0037] The ECU 39 calculates a coolant temperature correction factor mlsthw on the basis
of the coolant temperature TWH detected by the coolant temperature sensor 57 and the
data table of the coolant temperature correction factor 121 shown in Fig. 5. For instance,
it the coolant temperature THW is -20°C, the coolant temperature correction factor
mlsthw is set to be 0.5 (step S102). In the other case, if the coolant temperature
THW is +20°C, the coolant temperature correction factor mlsthw responsive to the THW=+20°C
is given by calculating the linear interpolation of the mlsthw=0.5 corresponding to
THW=-20°C and the mlsthw=0.76 corresponding to THW=+60°C.
[0038] Subsequently, the ECU 39 determines whether it is just after the engine 11 starts
or not (step S103). When it is not just after the engine 11 starts, an elapsed correction
factor mlast is set to be 1 (step S105).
[0039] When it is just after the engine 11 starts, the ECU 39 begins to measure the time
elapsed after starting the engine 11 by a timer or a time measuring means (not shown
in the figures) contained in the ECU 39. Furthermore, the ECU 39 determines a stabilization
time tmlast after starting the engine 11, on the basis of the coolant temperature
THW and the data table of the stabilization time 131 shown in Fig. 6 (step S104).
For example, if the coolant temperature is -20°C, the stabilization time tmlast is
set to be 30. If the coolant temperature is +20°C, the stabilization time tmlast corresponding
to the THW=+20°C is given by calculating the linear interpolation of the tmlast=10
corresponding to THW=0°C and the tmlast=0 corresponding to THW=+70°C.
[0040] The ECU 39 calculates the elapsed correction factor mlast by substituting the elapsed
time cast and the stabilization time tmlast calculated in the step S104 into the following
equation (1).
(a)
(b)
[0041] According to the above-mentioned equation (1), when the elapsed time cast is less
than or equal to the stabilization time tmlast, the elapsed correction factor mlast
is 0, just after the engine 11 starts. When the elapsed time cast becomes greater
than the stabilization time tmlast, the elapsed correction factor mlast increases
corresponding to the elapsed time, and finally the value of the mlast reaches 1.
[0042] Subsequently, the ECU 39 yields the target throttle angle LSTRG, substituting the
base throttle angle LSBSE, the coolant temperature correction factor mlsthw, and the
elapsed correction factor mlast into the following equation (2) (step S106).
[0043] The greater the coolant temperature correction factor mlsthw and/or the elapsed correction
factor mlast, the greater (toward the more closed direction) the target throttle angle
LSTRG is, according to the equation (2). Consequently, the higher the coolant temperature
THW and the longer the elapsed time cast, the more closed (the lower) the target throttle
angle LSTRG is set to be. Stated differently, the lower the coolant temperature THW
and the shorter the elapsed time cast, the more open (the higher) the target throttle
angle LSTRG is set to be.
[0044] After the target throttle angle is determined in the aforementioned procedure, the
ECU 39 controls the actual throttle angle 25 to reach the target throttle angle LSTRG
by controlling the step motor 26.
[0045] In this control, the target throttle angle LSTRG is set to be more open just after
the engine 11 starts, and the target throttle angle LSTRG changes toward the more
closed side in response to the elapsed time cast. Therefore the combustion condition
of the combustion chamber 12 can be optimized, according to the swift and smooth temperature
rise of the combustion chamber 12. Besides, although the coolant temperature THW rises
slowly after starting the engine 11, the target throttle angle LSTRG is controlled
notwithstanding the coolant temperature THW, and the combustion condition can thus
be reliably optimized. Furthermore, the lower the coolant temperature THW, the more
open the target throttle angle LSTRG is set to be. This also causes the combustion
condition to be optimized. By these above-mentioned advantages, the engine 11 is prevented
from misfiring or exhausting white smoke.
[0046] Incidentally, in this embodiment, the target throttle angle is calculated by the
equations (1) and (2). However, it is not limited only to this method, and the target
throttle angle LSTRG can be calculated by other methods. One example is described
as follows referring to Fig. 7. As shown in the graph, a correction factor for the
base throttle angle LSBSE (equivalent to mlsthw × mlast in the equation (2)) corresponding
to the elapsed time cast is beforehand given as each graph of THW=0°C, THW=40°C, THW=70°C.
If the coolant temperature is THW=0°C at starting the engine 11, the correction factor
is selected using the graph of THW=0°C in Fig. 7 and the target throttle angle LSTRG
is calculated using the correction factor and the elapsed time cast. When the coolant
temperature THW is in the middle between 0°C and 40°C or between 40°C and 70°C, the
target throttle angle LSTRG is calculated by linear interpolation.
[0047] The present invention is not limited to the aforementioned embodiment and can be
modified for many other embodiments. For example, in the equation (2) the base throttle
angle LSBSE is corrected by the coolant temperature correction factor mlsthw and the
elapsed correction factor mlast. However, it is also effective to correct the base
throttle angle LSBSE by an atmospheric pressure correction factor, an intake air temperature
correction factor, the elapsed correction factor mlast, etc., and to give the target
throttle angle LSTRG.
[0048] Besides, the data in the data tables in the above-mentioned embodiment is one example,
and it is also permissible to modify the data adequately, according to the engine
specification. Furthermore, as mentioned above, this embodiment is explained by using
the diesel engine 11. However, it is not limited to only diesel engines but also is
applicable to all internal combustion engines.
[0049] In the above-mentioned embodiment, in the internal combustion engine starting, the
target throttle angle LSTRG is controlled to be more closed in accordance to the elapsed
time cast after starting the internal combustion engine. Another embodiment can be
realized, however, only in the diesel engine, which is an internal combustion engine.
That is, a fuel injection timing to the combustion chamber 12 of the diesel engine
11 is controlled in response to the elapsed time cast.
[0050] A flowchart in Fig. 8 shows a target injection timing setting routine of another
embodiment of this invention. First, the ECU 39 determines the base fuel injection
timing ABSE, corresponding to the engine revolutions NE and the amount of fuel injection
QFiN, referring to the data table of fuel injection timing 211 shown in Fig. 9 (step
S201).
[0051] In the data table 211, the vertical line shows an instructed amount of fuel injection
QFiN, and the horizontal line shows the engine revolutions NE. The higher the amount
of fuel injection QFiN, the more advanced the base fuel injection timing ABSE is.
The higher the engine revolutions NE, the more advanced the base fuel injection timing
ABSE is.
[0052] Subsequently, the ECU 39 calculates fuel injection cool correction factor ATHW responsive
to the engine revolutions NE and the coolant temperature THW detected by the coolant
temperature sensor 57, by referring to a data table 221, that shows the fuel injection
cool correction factor ATHW corresponding to the coolant temperature in Fig. 10 (step
S202).
[0053] In the data table 221, the vertical axis shows the coolant temperature THW, and the
horizontal axis shows the engine revolutions NE. The lower the coolant temperature
THW, the more advanced the fuel injection timing is. The lower the engine revolutions
NE, the more advanced the fuel injection timing is.
[0054] In the next step, the ECU determines whether the engine 11 just started or not (step
S203). When the engine 11 has not just started, the ECU 39 sets the fuel injection
timing correction factor AAST to 0 (from step S203 to step S205).
[0055] On the other hand, when the engine 11 has just started, the ECU 39 begins to measure
the elapsed time cast by the timer (not shown in the figures). Furthermore, the ECU
39 determines the elapsed stabilization time tmlast on the basis the coolant temperature
THW detected by the coolant temperature sensor 57 and the data table 131 in Fig. 6
(step S204).
[0056] Next, the ECU 39 calculates a fuel injection timing correction factor AAST by substituting
the elapsed time cast and the stabilization time tmlast into the following equation
(3).
[0057] According to the equation (3), the fuel injection timing correction factor AAST is
the greatest when the engine 11 just starts. The AAST changes from the greatest value
and finally reaches 0 as the elapsed time cast becomes longer.
[0058] Subsequently, the ECU 39 calculates a target fuel injection timing ATRG by substituting
the base fuel injection timing ABSE, the fuel injection cool correction factor ATHW,
and the fuel injection timing correction factor AAST into the following equqation
(4).
[0059] Here, in the starting operation of the engine 11, the base fuel injection timing
ABSE is substantially kept constant in a predetermined time, as shown in Fig. 11.
The fuel injection cool correction factor ATHW is also substantially kept constant,
because the coolant temperature THW changes slowly. The fuel injection timing correction
factor AAST, however, changes in response to the elapsed time cast and finally becomes
0. Consequently, the target fuel injection timing ATRG changes according to the fuel
injection timing correction factor AAST in starting the engine 11.
[0060] Once the target fuel injection timing ATRG is calculated in this procedure, the ECU
39 determines the target fuel injection timing ATRG on the basis of the rotating position
of the crankshaft 21 detected by the revolution speed sensor 56, and directs the fuel
injection nozzle 17 to inject the fuel from the fuel injection pump 18 into the combustion
chamber 12, at the timing of the target fuel injection timing ATRG.
[0061] In this fuel injection timing control, the fuel injection timing correction factor
AAST changes according to the elapsed time cast, as mentioned above. Consequently,
the target fuel injection timing ATRG is set to be advanced when the elapsed time
cast is short and is set to be delayed when the elapsed time cast is long. Therefore,
the target fuel injection timing ATRG is controlled adequately in response to the
swift rising of the temperature of the combustion chamber 12 after starting the engine
11. The combustion condition of the combustion chamber 12 is thus optimized.
[0062] In the above-mentioned embodiment the fuel injection timing is controlled. However,
it is also effective that not only the fuel injection timing but also the throttle
angle (the above-mentioned control of the target throttle angle LSTRG) and the fuel
injection timing are controlled responsive to the elapsed time.
[0063] In the aforementioned embodiment, on the basis of the coolant temperature and the
elapsed time after the start of the internal combustion engine, a correction factor
for the base throttle angle corresponding to the temperature of the combustion chamber
is calculated such that the combustion condition in the combustion chamber is optimized.
In the present invention, however, it is not limited to the aforementioned values
for calculating the correction factor. Alternatively, the temperature of the combustion
chamber can be estimated on the basis of the lubricant temperature and the exhaust
gas temperature so as to correct the base throttle angle. It is also possible to calculate
the correction factor for the base throttle angle on the basis of the above two temperature
values and the elapsed time after the start of the internal combustion engine. Further,
in addition to the temperature values of the coolant, lubricant, exhaust gas or the
like, for example, the integrated amount of the intake air after the start of the
internal combustion engine can be used for determining the correction factor for the
base throttle angle corresponding to the temperature of the combustion chamber.
[0064] Furthermore, controlling the quantity of the exhaust gas recirculation and/or the
fuel injection ratio just after starting the engine is also effective. In a diesel
engine which can conduct pilot fuel injection, such as a common rail type diesel engine,
it is also effective to vary the interval between the pilot fuel injection and the
main fuel injection. By these controls, the combustion condition of the combustion
chamber can also be optimized. Summing up these control, the combustion condition
of the combustion chamber can be reliably optimized by adequately combining the respective
controls such as the fuel injection timing, the target throttle angle, the quantity
of the exhaust gas recirculation, the fuel injection ratio, the interval between the
pilot and the main fuel injection, etc.
[0065] While the present invention has been described with reference to what are presently
considered to be preferred embodiments thereof, it is to be understood that the invention
is not limited to the disclosed embodiments or constructions. On the contrary, the
invention is intended to cover various modifications and equivalent arrangements.
In addition, while the various elements of the disclosed invention are shown in various
combinations and configurations, which are exemplary, other combinations and configurations,
including more, less or only a single embodiment, are also within the spirit and scope
of the invention defined in the appended claims.
[0066] The present invention offers a control device of an engine intake throttle valve
25 which optimizes a combustion condition of a combustion chamber 12 when an internal
combustion engine 11 starts. The shorter an elapsed time after starting the engine,
the higher a target throttle angle of the intake throttle valve 25 is. The target
throttle angle changes to be lower in response to swift rising of the temperature
of the combustion chamber 12, just after the engine 11 starts. Therefore the combustion
condition of the combustion chamber 12 is optimized in the operation of starting the
engine 11. Furthermore, the target throttle angle LSTRG is controlled according to
the elapsed time after starting the engine 11, even though the coolant temperature
changes slowly. Then, the combustion condition of the combustion chamber 12 is reliably
optimized.
1. A control device for controlling an intake throttle valve (25) in an intake air flow
passage to a combustion chamber (12) in an internal combustion engine (11), characterized
in that the control device comprises:
a combustion chamber temperature estimation means for estimating a temperature of
a combustion chamber in said internal combustion engine; and
a control means (39) for setting a throttle angle of said intake throttle valve on
the basis of the temperature of the combustion chamber detected by said combustion
chamber temperature estimation means after said internal combustion engine starts.
2. A control device for controlling an intake throttle valve according to claim 1, characterized
in that said combustion chamber temperature estimation means comprises:
a temperature detection means (57) for detecting a coolant temperature of said internal
combustion engine; and
a time measuring means for measuring an elapsed time after said internal combustion
engine starts, wherein
said control means sets the throttle angle of said intake throttle valve on the basis
of the coolant temperature detected by said temperature detection means and the elapsed
time measured by said time measuring means.
3. A control device for controlling an intake throttle valve according to claim 2, characterized
in that the shorter the elapsed time measured by said time measuring means becomes,
the higher the throttle angle of said intake throttle valve is set.
4. A control device for controlling an intake throttle valve according to claim 3, characterized
in that the lower the coolant temperature detected by said temperature detection means
becomes, the higher the throttle angle of said intake throttle valve is set.
5. A control device for controlling an intake throttle valve according to claim 3 or
4, characterized in that the throttle angle of said intake throttle valve is kept
constant only for a predetermined time after said internal combustion engine starts.
6. A control device for controlling an intake throttle valve according to claim 2, characterized
in that said control means sets a fuel injection timing of said internal combustion
engine on the basis of the coolant temperature detected by said temperature detection
means and the elapsed time measured by said time measuring means.
7. A control device for controlling an intake throttle valve according to claim 6, characterized
in that the shorter the elapsed time measured by said time measuring means becomes,
the more said fuel injection timing is advanced.
8. A control device for controlling an intake throttle valve according to claim 6, characterized
in that the lower the coolant temperature detected by said temperature detection means
becomes, the more said fuel timing is advanced.
9. A control device for controlling an intake throttle valve according to claim 7 or
8, characterized in that the shorter the elapsed time measured by said time measuring
means becomes, the higher the throttle angle of said intake throttle valve is set.
10. A control device for controlling an intake throttle valve according to claim 7 or
8, characterized in that the lower the coolant temperature detected by said temperature
detection means becomes, the higher the throttle angle of said intake throttle valve
is set.
11. A control device for controlling an intake throttle valve according to claim 7 or
8, characterized in that said fuel injection timing is kept constant after the elapse
of the predetermined time subsequent to the start of said internal combustion engine.
12. A control device for controlling an intake throttle valve according to claim 1, characterized
in that said internal combustion engine (11) is a diesel engine.